“Perfect Knowledge of Piping Engineering”
A Practical Guide in Engineering Technique for Mechanical Engineering Degree/Diploma final year student preparing for service interview. I do not claim that “Perfect Knowledge of Piping Engineering” is the final word in Piping Engineering. I have tried my best to share the knowledge and experience being common to more Engineers who came forward to co-operate in the field of knowledge and pool their experience to make it better for the Mechanical Engineers whether final year students or fresher in service or working as a junior Engineer in construction field and doing the Piping Engineering job. It is easy to grasp the basic knowledge and principles of Piping Engineering This book is devised and planned to be practical help and is made to be most valuable reference book. I will feel myself proud that my efforts are rewarded, if this book contributes even to a small group of students or fresher or working junior Engineer in acquiring and understanding of the subject. I sincerely record my gratitude to Mr. Ram Babu Sao, experienced and versatile Mechanical Engineer and friend of mine whose promise and unstinted labour in providing assistance to publish this book. Otherwise this book could have not been published. I acknowledge his contribution gratefully. I am extremely grateful to all those who have assisted me in bringing out this edition of the book. Mumbai
Sanjay Kumar Gupta
August 2015
@
Copyright: Author-2004 CAUTION
All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical including photocopy without permission in writing from the publishers.
Disclaimer The book “ Perfect Knowledge of Piping Engineering” is not a writer’s whole & sole product. It is a combination of the knowledge and expertise of the author and the Data collected from different Codes, Standards and Books, specially researched to meet the objective and to enhance the knowledge of piping engineers. Wherever necessary, the reference of the Codes, Standards or other Books has been given in this book. The Data in this book provides only information, knowledge, guidance and reference to engineers and shall not permit the engineers to use these Data for designing any piping system. ISBN-13: 978-1511561624 ISBN-10: 1511561629 First Edition: August, 2015 Publisher: Amazon
Preface It gives me great pleasure and sense of deep satisfaction to publish this book of “Perfect Knowledge of Piping Engineering”. This book has proved to be a friend and guide to many Engineering Students, Engineers, Contractors, Construction Companies and Consultants. The total practical approach of this book explodes the math that, even the piping engineering subject is tough and difficult to understand, a general reader or beginners willing to know about the subject, will find the content very easy and simple to follow. The excellence of the book will be appreciated by the readers from all parts of India and abroad after publication of the First Edition. There is so much strife and struggle in the present time as it was never before. This is a time of readymade food and fast food. Nobody has time to cook the food and then eat. Only this feeling motivated me and necessitated in publishing this book. This is compact and full of all information at one place in a simple language. Today the eyes of the whole of the world are fixed on India for any kind of development. The need for development has been felt for quite some time back that this book is written on piping work which may contain all the aspect of piping with illustrations so that complete information is conveyed in a simple language. I am confident that this book will help to all technicians, supervisors, and engineers in achieving his object and success in every field of piping work. I have given the gist of Indian and international books, standards, codes, and specifications on piping work in this book. At the same time, I have tried to make you understand about what is the piping work. These facts & figures are collected from various books, standards, and specifications and incorporated here in this book for the first time for reference by the common technical men. Behind all this, there is our exhaustive study and collections. More than the study is the presentation of the subject matter and even much more than the presentation of the subject matter is long years of experience and association with the piping work all over India and abroad while working with M/S Engineers India Limited, an internationally reputed engineering consultancy organization. This adds some kind of value to the book. A systematic, consistent, and clear presentation of concepts through explanatory notes, figures, and examples are the main aspects of this book. While publishing this book, I have constantly kept in mind the requirements of all engineering professionals, and the various difficulties they face while performing their job. To make the book really useful at all levels, it has been written in an easy style and in a simple manner, so that a professional can grasp the subject independently by referring this book. Care has been taken to make this book as self-explanatory as possible and within the technical ability of an average professional.
In short, it is earnestly hoped that this treatise will earn the appreciation of all technical professional all over the world.
Contents 1. 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1.11 2. 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 3. 3.1 3.2
Introduction Measures & Weights Units Conversion Physics Hydraulic engineering Chemistry Mathematics Abbreviations Definitions List of Codes and Standards List of Vendors and Manufacturers Books Catalogues Piping Materials Materials Classification Metallurgical Structure of Metal Mechanical Properties Factors Affecting Mechanical Properties Temperature Affecting Mechanical Properties Factors Affecting Service Feature Elements affecting Alloy Steel Selection of Piping Materials Piping Materials for Specific Fluid Services Piping Material-Identification Corrosion of Piping Metal Theory of Corrosion Factors Affecting Corrosion
1-112 1-5 5-12 12-30 30-36 36-39 39-57 57-63 63-102 102-107 107-111 111-112 113-162 113-127 127-132 132-134 134-135 136-137 138-140 140-145 146-153 154-161 161-162 163-186 163-167 167-168
3.3 4. 4.1 4.2 4.3 4.4 4.4.1 4.4.2 4.5 4.5.1 4.5.2 4.6 4.6.1 4.6.2 4.6.3 4.6.4 4.7 4.8 4.9 4.10 4.11 4.12 4.13 5. 5.1 5.2 5.3 5.4 5.5 6. 6.1 6.2 6.3 6.4 6.5 6.6 7. 7.1 7.2 7.2.1 7.2.2 8.
Corrosion Table Piping Design General Design Requirements Design Conditions Piping Design Criteria- “Part-1” “Temperature-Pressure Rating” Design Criteria “Stress – Strain” Design Criteria Piping Design Criteria-“Part-2” Pressure Integrity-Design Pipe Wall Thickness (tm.) Piping Design Criteria-“Part-3 “ Sizing of Liquid Line-Single phase Sizing of Gas Line-Single Phase Sizing of Liquid / Gas Line-Two Phase Pipe Sizing in Steam System Piping Flexibility and Supports-Design Piping Supports-Design Piping Joints-Design Design Engineering and Limitations Piping Engineering Standard-Data Plant Layout Design Example 1 Piping Components Pipe and Tube Pipe Fittings Flanges Valves Piping other Components Piping Project Management Project Introduction Project Management Network Analysis Package Scheduling Technique Project Monitoring System Standard Man-hour for Piping Piping Assembly Applicable Codes and Standards Piping Fabrication and Assembly Piping Cutting Piping Fabrication Piping Welding
168-186 187-452 187-188 188-191 191-201 201-363 202-359 359-363 363-366 363-364 364-366 366-396 367-376 376-377 377-384 384-396 396-406 406-421 421-423 424-427 427-438 438-448 448-452 453-528 453-463 463-473 473-486 486-505 505-528 529-542 529-529 529-531 531-534 534-537 537-539 539-542 543-560 544-544 544-560 445-554 554-560 561-626
8.0 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 8.10 8.11 8.12 8.13 8.14 9. 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 9.10 9.11 9.12 9.13 9.14 9.15 9.16 9.17 9.18 9.19 9.20 9.21 9.22 9.23 9.24 10. 10.1 10.2 10.3 11.
Applicable Codes of Welding Welding Symbols Welding Joint Type Weld Orientation Welding Accessories Typical Metal Welding Welding of Dissimilar Metals Estimation of Welding Cost Welding Defects Welding Distortion & Remedies Welding Variables & Positions Welding Procedure Specification (WPS) Welding Procedure Qualification Records (PQR) Welder Performance Qualifications (Certification) WPS / PQR Qualification tests Piping Inspection General Applicable Codes and Standards Levels of certification Destructive Examinations & Tests Non-Destructive Test N.D.T Examination Requirements Weld Imperfections and Acceptance Limit Inspection and Testing Instruments Visual Inspection Radiographic Inspection (RT) Magnetic Particle Examination Eddy current Dye penetrant Test (DPT / LPT) Ultrasonic Test (UT) Hardness Test Hydrostatic Test Pneumatic Test Hydrostatic-Pneumatic Test Sensitive Leak Test Gas and Bubble Solution Test Vacuum Box Test Alternative Leak Test Repair of Weld Documentation and Records Piping Heat Tracing General Steam Tracing Applications Inspection and Testing Lined Piping
561-574 574-580 580-584 584-588 588-593 593-594 594-597 597-599 600-603 603-607 607-611 612-619 619-622 622-625 625-626 627-694 627-627 627-630 630-631 631-632 632-634 634-642 642-643 643-644 644-649 649-669 669-672 672-673 674-675 675-682 682-684 684-690 690-691 691-691 691-692 692-692 692-693 693-693 693-693 693-694 695-702 695-695 695-702 702-702 703-712
11.1 11.2 11.3 12. 12.1 12.2 12.3 12.4 13. 13.0 13.1 13.2 13.3 13.4 13.5 13.6 13.7 13.8 13.9 14 14.1 14.2 14.3 14.4 14.5 14.6 15. 16. 16.0 16.1 16.2 16.3 16.4 16.5 16.6 16.7 16.8 17. 17.1 17.2 17.3
General Plastic Lined Piping Systems Other Lined Piping Systems Jacketed Piping General Piping Sizing Jacketed Piping Systems Leak Test Piping Painting General Painting Applicable Codes Paint Materials Primer Paint Materials Selection Finish Paint Materials Selection Painting Surface Preparation Paint Application Colour Coding Painting Inspection Piping Coating & Wrapping General Applicable Codes and Standards Coating & Wrapping Materials Surface Preparation Application Inspection Cathode Protection Piping Insulation General Applicable Codes Properties of Thermal Insulation Theory of Heat Loss Theory of Heat transfer Insulation Materials Application of Cold Insulation Application of Hot Insulation Insulation Inspection Non-Metallic Piping Plastic Piping Systems Rubber and Elastomeric Piping Systems Thermo Set Piping Systems
703-706 706-712 712-712 713-722 713-719 719-720 720-720 720-722 723-736 723-723 723-724 724-725 725-726 726-728 728-729 729-731 731-733 733-734 734-736 737-742 737-737 737-737 737-739 739-740 740-741 741-742 743-746 747-762 747-747 747-747 748-753 753-753 753-754 754-758 758-760 761-762 762-762 763-784 763-771 771-777 777-784
1 Introduction 1.1
Measures & Weights Units
There are different unit of measures and weights being used in the world. This chapter is intended to guide for expressing weight and measures, their units and symbols. The list of codes and standards of weights and measures, their units and symbols are also given here for further reference: 1) ASTM E380 : Standard for Metric Practice. 2) ASTM E268 : Standard for Metric Practice 3) NIST SP-330 : National Institute of Standards and Technology. 4) American National Metric Council : Metric Editorial Guide 5) ASME Guide S 1.1 : ASME Orientation Guide for use of SI (Metric) Units. The International System of Units (SI) on Weights and Measures has the Base units along with the Derived units. The “Absolute units” or Base units are seven, as given below. Meter: The Meter is the unit of Length. The Meter is the length of the path travelled by light in vacuum during a time interval of 1/299792458 of a second. It follows that the speed of light in vacuum is 299792458 meters per second, i.e. 299 792 458 m/s. Kilogram: The kilogram is the unit of Mass. It is equal to the mass of the international prototype of the kilogram; an artefact made of platinum-iridium and is kept at the BIPM. Table: Absolute SI units Base quantity
Name of Units
Length Mass Time Electric current Thermodynamic temperature Amount of substance Luminous intensity
Meter Kilogram Second Ampere Degree Kelvin
Symbol Quantity m kg s A °K
Mole
mol
Candela
cd
for
Second: The second is the unit of Time, precisely defined by the International Astronomical Union based on a transition between two energy levels of an atom or a molecule, which is much more accurate. The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom. This unit of
second is a very precise definition of the unit of time and is indispensable for science and technology. Another definition of Second is the unit of time and is equal to the fraction 1/86400 of the Mean Solar Day defined by the astronomers. But due to irregularities in the rotation of the Earth made, this definition of Second is an unsatisfactory definition. Ampere: Ampere is the unit for Current. The ampere is that constant current, which produce a force equal to 2 x 10–7 Newton per meter of length between two straight parallel conductors of infinite length and of negligible circular cross-section and placed 1 meter apart in vacuum. It follows that the magnetic constant, 0, known as the permeability of free space, is exactly 4 x 10–7 henries per meter, 0 = 4 x 10–7 H/m. Temperature: The Kelvin and the degree Celsius are units of Temperature. Kelvin is the unit of Thermodynamic Temperature, which is assigned to the temperature 273.16 K. The Kelvin is the fraction 1/273.16 of the Thermodynamic Temperature of the triple point of water. The triple point of water has the isotopic composition amount of substance ratios, e.g., 0.000 155 76 moles of 2H per mole of 1H; and 0.000 379 9 mole of 17O per mole of 16O; and 0.002 005 2 mole of 18O per mole of 16O. Thermodynamic Temperature is expressed as a symbol T, in terms of its difference from the reference temperature T0 = 273.15 K, the ice point. This difference is called Celsius temperature, symbol t, which is defined by the quantity equation: t = T – T0. The unit of Celsius temperature is the degree Celsius, symbol °C, which is equal in magnitude to the Kelvin. A difference or interval of temperature may be expressed in Kelvin or in degrees Celsius, the numerical value of the temperature difference being the same. However, the numerical value of a Celsius temperature expressed in degrees Celsius is related to the numerical value of the Thermodynamic Temperature expressed in Kelvin by the relation: t/°C = T/K – 273.15. Mole: The mole is the unit of an amount of a substance which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12 and its symbol is "mol". The molar mass of carbon 12 is exactly 12 grams per mole, M (12C) = 12 g/mol. Gram-atom/Gram-molecule: "Gram-atom" and "Gram-molecule" is the Units of an amount of chemical element or compound. These units have a direct connection with "atomic weights" and "molecular weights", which are in fact relative masses. "Atomic weights" are referred to the atomic weight of oxygen. Physicists separate the isotopes in a mass spectrometer and attribute the value 16 to one of the isotopes of oxygen. Chemists attribute the same value to the mixture of isotopes 16, 17 and 18. Candela: The candela is the unit of Luminous Intensity of Light in a given direction that emits monochromatic radiation of frequency 540 x 1012 hertz and has a radiant intensity in the same direction of 1/683 watt per Steradian. It follows that the spectral luminous efficacy for monochromatic radiation of frequency of 540 x 1012 hertz is exactly 683 lumens per watt, K = 683 lm/W = 683 cd sr/W. Derived Units: Derived units are the units formed by combining Base Units based on the algebraic relations linking to the Base Units. The dimensions of the Derived quantities are written as products of powers of the dimensions of the Base quantities using the equations that relate the Derived quantities to the Base quantities. Nautical Mile: A Nautical Mile or Sea Mile is the distance on the earth’s surface at the sea level and corresponds to approximately one minute of arc (1/60 of a degree) of longitude on the equator of the earth. Knot: Knot is a unit of speed of a ship or travel of a ship per hour and is equal to one U.K. Nautical Mile per hour. The knot is a non-SI unit accepted for use with the International System of Units (SI). It
is a speed of vessel travelling at 1 knot along a meridian travels one minute of geographic latitude in one hour. Parsec: The parsec (pc) is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion (3.1×1013) kilometres or about 19 trillion miles. A parsec is the distance from the Sun to an astronomical object which has a parallax angle of one arc second and is one of the oldest methods for astronomers to calculate the distance. Table: Derived units Base quantity Area Volume Frequency Density
Name of Units
square meter cubic meter hertz kilogram per cubic meter Velocity meter per second Angular radian per Velocity second Acceleration meter per second squared Angular radian per Acceleration second squared Angular radian per Acceleration second squared Force Newton Pressure or Newton per Stress square meter or Pascal Kinematics square meter Viscosity per second Dynamic Newton-second Viscosity per square meter Work or joule Energy or Quantity of heat Power watt Quantity of coulomb Electricity “Electric volt Potential
Symbol
Units
m2 m3 Hz kg/m3
[L]2 [L]3 1/s
m/s
[L][T]−1
rad/s m/s2 rad/s2
[L][T]−2
rad/s2
[L][T]−2
N N/m2 or Pa
kg · m/s2 [M] [T] [L]−1
m2/s N· s/m2
J
N·m
W C
J/s A· s
V
W/A
Difference” or “Electro Motive Force” (EMF) Electric Resistance magnetic Field Strength Magneto Motive Force Luminance Plane Angle Dynamic Viscosity Moment of Force Surface Tension Heat Capacity, Entropy Thermal Conductivity Energy Density Electric Field Strength Molar Energy Exposure of X – Ray and Gamma-Rays Absorbed Dose Rate Molar Entropy, Molar Heat Capacity Radiant Intensity
ohm ampere meter ampere
V/A per A/m A
candela per cd/m2 square meter radian rad Pascal second Pa s
m–1 kg s–1
Newton meter
m2 kg s–2
Newton meter joule Kelvin
Nm
per N/m
kg s–2
per J/K
m2 kg s–2 K– 1
watt per meter W/(m K) Kelvin joule per cubic J/m3 meter volt per meter V/m
m kg s–3 K–1
joule per mole
m2 kg s–2 mol–1 kg–1 s A
coulomb kilogram
J/mol
per C/kg
m–1 kg s–2 m kg s–3 A–1
gray per second Gy/s
m2 s–3
joule per mole J/(mol K) Kelvin
m2 kg s–2 K– 1 mol–1
watt steradian
m4 m–2 kg s– 3
per W/sr
1.2 Quantity Length
Conversion Unit Parsec
Light Year Pent meter Tetra meter Giga meter Mega meter Hector kilometre Kilo meter Hector meter Decca meter Meter Decimetre Centimetre Millimetre Micrometer (Micron) Nanometre (Mill micron) Parsec League (UK Nautical) Nautical mile (US) Nautical mile (UK) International Nautical mile Mile /Land Mile / Canal Mile
Cable Length Cable (UK) Furlong Chain (Engineer) Chain (Surveyor)
Rod / Pale / Perch Fathom Yard Link (Engineer) Link (Surveyor) Span Meter Foot Inch Inch Inch Inch Inch Kilometre cm Foot Meter Yard Meter Micro-meter Mil Area
Volume
1 sq. cm 1 sq. in 1 sq. m 1 sq. yard 1 acre
1 sq. Mile 1 in3 1 ft3 1 fluid oz
1 Gallon 1 Litter
1 American Gallon
1 Imperial Gallon
1 American Barrel 1 Pint 1 quart 1 Kilo litter 1 Gram-molecule (a gas at 0 c and 760 mm of mercury pressure) volume
Mass / Weight
1 Ton (metric)
1 Ton (British) 1 Pound (lb) 1 Kg 1 Tola 1 Gram
1 Ounce 1 Metric carat
Pressure
1 Troy Ounce 1 Troy ounce 1 slug 1 ATM
/ Stress
1 bar
1 Kg / cm2 1 lbf / in2 (psi)
1 tore (mm Hg. at 00c) 1 lb. / ft2 1 lb. / ft2 1 lb / ft2 1 Pa (Pascal) 1 N / mm2 1 N / mm2
Power
1 in. Hg at 320 F 1 ton / in2 1 kg / mm2 1 ksi 1 lb/in2 (psi) 1 MN / m2 1 W / in2 1 Watt 1 Btu / s
1 Btu / min. 1 Btu / h 1 erg / s 1 ft. lbf / s 1 ft. lbf / min 1 ft. lbf / h 1 hp 1 hp (Metric)
1 hp (electric)
1 (w)
Angle Torque Bending Moment
Current Density
Electricity
Magnetism Specific Heat
Temperature
Thermal Conductivity Thermal Expansion Energy (Impact)
1 Horse Power (Boiler) 1 ton (Refrigeration) 1 Degree 1 lbf-in. 1 lbf-ft. 1 kgf-m 1 ozf-in. 1 lb. in / in. 1 lbf. ft / in 1 A / in. 2 1 A / in. 2 1 A / ft2 1 gauss 1 ohm-cm 1 Oersted 1 mho 1 Btu / lb. 0F 1 cal / g. 0C 1 0C 1 0F 1 0R 1 Btu / ft2. s. 0F 1 Btu / ft2. h. 0F 1 Cal / cm2. s. 0C 1 in / in. 0C 1 in / in. 0F 1 lb.ft. 1 Btu 1 kW. h
Flow Rate
1 Cal 1 W.h 1 Ft.3/h 1 ft3/min 1 gal. /h
1 gal. /min 1 ft3 / min 1 ft3 / s 1 in3 / min 1 lbf Force 1 kip 1 kip 1 tonf 1 kgf Force per unit 1 lbf / ft length 1 lbf / in 1 Ksi / in Fracture Toughness 1 Btu / lb Heat content 1 Cal / g 1 ft / h Velocity 1 ft / m 1 ft /s 1 km / h 1 mph Velocity of 1 rev / m (rpm) Rotation 1 rev / s Viscosity
Heat Input Capacity (Crude Oil)
1 poise 1 stokes 1 ft2/s 1 in2/s 1 J / in 1 KJ / in 1 ton/year 1 Barrel/day
Birmingham Wire Gauge: The wire thickness in Gauge Number and its conversion in decimal part
of an inch are given rather than as fraction or gage. When gauge numbers is given for a wire without reference to a system, it means that it is Birmingham Wire Gauge (BWG). Birmingham Wire Gauge is also known as Stubs' Wire Gauge, used for drill rod and tool steel wire. BI RMI NGHAM WI RE G AUGE (BWG) / S TUBS ’ WI RE G AUGE (SWG) SWG
Dimension (mm) 00000 (5/0) 12.70 0000 (4/0) 11.53 000 (3/0) 10.80 00 (2/0) 9.65 0 8.64 1 7.65 2 7.01 3 6.40 4 5.89 5 5.39 6 4.88 7 4.47 8 4.06 9 3.66 10 3.25 11 2.95 12 2.64 13 2.34 14 2.03 15 1.83
SWG 16 17 18 19 20 21 22 24 26 27 28 29 30 31 32 33 34 35 36 --
Dimension (mm) 1.63 1.42 1.22 1.02 0.914 0.813 0.711 0.559 0.457 0.406 0.356 0.330 0.305 0.254 0.229 0.203 0.178 0.127 0.102 --
LI GHT TRAVEL TI ME FOR Distance one foot one meter one kilometre one statute mile Geostationary orbit to Earth Moon to Earth Sun to Earth (1 AU) Proximal Centauri to Earth Alpha Centauri to Earth Nearest Galaxy to Earth
A PARTI CULAR DI STANCE
Time 1.0 ns (Nanosecond) 3.3 ns (Nanosecond) 3.3 μs (Microsecond) 5.4 μs (Microsecond) 119 ms (Millisecond) 1.3 s (Second) 8.3 min (Minute) 4.24 years 4.37 years 25,000 years
Across the Milky Way 100,000 years Andromeda Galaxy to Earth 2.5 million years Furthest Observed Galaxy to 13 billion years Earth
1.3
Physics
Physics is a natural science, which studies the matter, its motion and behaviour of the universe through space, time and all related concepts including energy and force and is represented by, E = mc2
N EWTON ’S THREE LAW OF M OTION i) Newton’s of First Law Motion: Everybody continues in a state of rest or of uniform motion in a straight line unless it is compelled to change that state by a force imposed on the body. The First Law of Motion helps us to define a force. ii) Newton’s Second Law of Motion: The acceleration of a given particle is proportional to the imposed force and takes place in the direction of the straight line in which the force is impressed. This law helps us to measure a force quantitatively. F = ma iii) Newton’s Third Law of Motion: Every action has equal and opposite reaction. This means that the force of action and reaction between two bodies are equal in magnitude but opposite in direction. Energy: Energy is the ability to do the work on other physical systems. Energy is always equivalent to the ability to exert pulls or pushes against the basic forces of nature along a path of a certain length. Work: Work is force acting through a distance. Force: Force is the pull or push that causes a free body to undergo a change in speed, a change in direction, or a change in shape and causes an object with mass to change its velocity or to move from a state of rest, to accelerate, or to deform the flexible object. A force is a vector quantity and has both magnitude and direction. Power: Power is the rate at which work is performed or energy is converted. It is the average amount of work done or energy converted per unit of time. If ΔW is the amount of work performed during a period of time of duration DT, the average power Pavg over that period is given by the formula:
In the case of constant power P, the amount of work performed during a period of duration T is given by:
Units of Power: The dimension of power is energy divided by time. The unit of power is the watt (W), which is equal to one joule per second. Horsepower: Horsepower (HP) is the name of units of measurement of power. Horsepower was originally defined to compare the output of steam engines draft horses power. Mechanical power: In mechanics, the work done on an object is related to the forces acting on it by
Where, F is force, Δd is the displacement of the object. The work is equal to the force acting on an object times its displacement. A force in the same direction as motion produces positive work, and a force in an opposing direction of motion provides negative work, while motion perpendicular to the force yields zero work. The power output of an engine is equal to the force it exerts multiplied by its velocity. In rotational systems, power is related to the torque (τ) and angular velocity (ω): or In systems with fluid flow, power is related to pressure, p and volumetric flow rate, Q:
Where, p is pressure (in Pascal, or N/m2 in SI units), Q is volumetric flow rate (in m3/s in SI units) Gravity: An initially stationary object which is allowed to fall freely under gravity drops a distance which is proportional to the square of the elapsed time. Example: An image, during the first 1/20th of a second, will drop one unit of distance (12 mm); during 2/20 of a second, it will drop 4 units (48 mm) and during 3/20 of a second, it will drop 9 units (108 mm) and so on. The force of gravity on an object at the Earth's surface is directly proportional to the object's mass. An object that has a mass of m will experience a force:
In free-fall, this force is unopposed and therefore the net force on the object is its weight. For objects not in free-fall, the force of gravity is opposed by the reactions of their supports. Newton’s Law of Gravitation: Two particles are attracted towards each other along the line connecting them with a force whose magnitude is proportional to the product of their masses and inversely proportional to the square of the distance between them. Such as, Where, r is the distance between two Masses; F is the force between the masses, G is the gravitational constant, m1 is the first mass, m2 is the second mass Assuming SI units, F is measured in Newton’s (N), m1 and m2 in kilograms (kg), r in meters (m), and the constant G is approximately equal to 6.674×10−11 N m2 kg−2. Centrifugal Force: Centrifugal Force acting on a concentrated mass = F, F = (W v2) / (g R) lb or F = (W R n2)/ (2936) lb Where, v = velocity on curve in feet per second. R = Radius of curvature in feet and W = Mass of the body and n = Revolution per minute Parallelogram Law of Force: If two forces acting at a point are represented in magnitude and direction by the adjacent sides of a parallelogram, then the diagonal of the parallelogram passing through their point of intersection represent the resultant in both magnitude and direction.
Triangle Law of Force: If a triangle with its adjacent sides equal and parallel to the forces P and Q is drawn, (head to tail) to a suitable scale, the closing side of the triangle taken in opposite direction represents the resultant R in magnitude and direction. Principle of Transmissibility of a Force: The condition of equilibrium or of motion of rigid body will remain unchanged if the point of application of a force acing on the rigid body is transmitted to act at any other point along its line of action. Rectangular Components of a Force:Any force (F) can be resolved into two rectangular components along the X-axis and the Y-axis, if it makes an angle of degree with the X-axis, then, Fx = the component of force (F) in direction of X-axis = F Cos Fy = the component of force (F) in direction of Y-axis = F Sin . Equilibrium: Equilibrium occurs when the resultant force acting on a point particle is zero. In other word, the vector sum of all forces is zero. There are two kinds of equilibrium, such as, Static equilibrium and Dynamic equilibrium. Static equilibrium: Objects which are at rest have zero net force acting on them. The simplest case of static equilibrium occurs when two forces are equal in magnitude but opposite in direction. Example: An object on a level surface is pulled (attracted) downward toward the centre of the Earth by the force of gravity. At the same time, surface forces resist the downward force with equal upward force. The situation is one of zero net force and no acceleration. Dynamic equilibrium: The study of the causes of motion and changes in motion is dynamics. In other words, the study of forces and motion is dynamics. Special relativity: In the special theory of relativity mass and energy are equivalent as can be seen by calculating the work required to accelerate an object. It thus requires more force to accelerate it the same amount than it did at a lower velocity.
Light: Light is electromagnetic radiation that is visible to the human eye and is responsible for the sense of sight. Light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz. In physics, the term light sometimes refers to electromagnetic radiation of any wavelength, whether visible. Primary properties of light are intensity, propagation direction, frequency or wavelength spectrum, and polarisation and its speed in a vacuum is 299,792,458 metres per second (about 300,000 kilometres per second) and is one of the fundamental constants of nature. Light, which is emitted and absorbed in tiny "packets" is called photons, exhibits properties of both waves and particles. This property is referred to as the wave– particle duality. The study of light is known as optics. Speed of light: The speed of light in a vacuum is defined to be exactly 299,792,458 m/s (approximately 186,282 miles per second). Refractive Index: The refractive index of a substance is a measure of the speed of light in that substance. It is expressed as a ratio of the speed of light in vacuum relative to that in the considered medium. The velocity at which light travels in vacuum is a physical constant, and is the fastest speed at which energy or information can be transferred. However, light travels slower through any given material. Mathematical description of the refractive index is as follows: n = c / v = velocity of light in a vacuum / velocity of light in medium. The Refractive Index of water is 1.33. This means that light travels in a vacuum is 1.33 times as fast as it does in water. The Refractive Index of glass is around
1.5, meaning that light in glass travels at c / 1.5 = 200,000 km/s; the refractive index of air for visible light is about 1.0003. The light we see from stars left them many years ago. Electricity: Electricity is a phenomena resulting from flow of electric charge. These include many phenomena, such as lightning, static electricity, and the flow of electrical current in electrical wires, the electromagnetic field and electromagnetic induction. Lightning is one of the most dramatic effects of electricity. “Electricity" refers to a number of physical effects and precise termed as: Ohm’s Law: When an electric potential V is applied across a material, a current of magnitude I flows. In most metals, at low values of V, the current is proportional to V, according to Ohm's law: I = V/R Where, R is the electrical resistance. R depends on the intrinsic Resistivity r of the material and on the geometry (length l and area A through which the current passes). R = r l / A Electrical Resistivity: Electrical resistivity is a measure of how strongly a material opposes the flow of electric current. A low resistivity indicates a material that readily allows the movement of electric charge. The SI unit of electrical resistivity is the ohm metre (Ωm). It is commonly represented by the Greek letter ρ (rho). Electrical conductivity: Electrical conductivity or specific conductance is the reciprocal quantity, and measures a material's ability to conduct an electric current. It is commonly represented by the Greek letter σ (sigma), but κ (in electrical engineering). Table 1: Electrical Properties of Materials
Material Air Aluminium Carbon Carbon (diamond) Carbon (graphite) Copper Drinking water Glass Gold Hard rubber Iron Lead
Electrical Properties of Materials Resistivity Conductivity Temperature ρ [Ω·m] at 20 σ [S/m] at 20 coefficient °C °C [K−1] 1.3×1016 to -3 to 8 × 10−15 16 3.3×10 0.0039 2.82×10-8 3.5×107 −0.0005 5×10-4 to 8×10-4 1.25 to 2×103 1×1012 2.5e×10-6 5.0×10-6 1.68×10-8
to
2×101 to 2×103 10×1010 10×1014 2.44×10-8 1×1013 1.0×10-7 2.2×10-7
to
~10-13
--
2 to 3×105
--
5.96×107
0.0039
5×10-4 to 5×10-2 -10-11 to 10-15
--
4.10×107 10-14 1.00×107 4.55×106
0.0034 -0.005 0.0039
Mercury Nickel PET Quartz (fused) Sea water Silicon Stainless steel
9.8×10-7 6.99×10-8 10×1020
1.02×106 1.43×107 10-21
0.0009 0.006 --
7.5×1017
1.3×10-18
--
2×10-1 6.40×102
4.8 1.56×10-3
-−0.075
6.897×10-7
1.450×106
10×1022 10×1024 5.90×10-8
Teflon Zinc
to
10-25 to 10-23
--
1.69×107
0.0037
Electric current: A movement or flow of electrically charge is known as an electric current, the intensity of which is usually measured in amperes. Current can consist of any moving charged particles; most commonly these are electrons, but any charge in motion constitutes a current. Ampere is the unit of current, which is defined as that constant current, which, if maintained in each of the two infinitely long straight parallel wires of negligible cross-section placed 1 metre apart, in vacuum, which produce between the wires a force of 2x10-7 Newton per Mitre length., typically measured in amperes. Electric field: An influence produced by an electric charge on other charges in its vicinity. Electrical power: Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt. The instantaneous electrical power P delivered to a component is given by;
Where, P (t) is the instantaneous power, measured in watts (joules per second); V(t) is the potential difference (or voltage drop) across the component, measured in volts; I(t) is the current through it, measured in amperes. Magnetic Field: The magnetic field is the magnetic force on an electric current at any point in space. In this case, the magnitude of the magnetic field is determined to be
, Where, I is the magnitude of the hypothetical test current and is the length of hypothetical wire through which the test current flows. Heat: Heat is one of the fundamental processes of energy transfer from a high-temperature system to a lower-temperature system due to difference in temperature between the physical entities. Latent heat: Latent heat is the heat released or absorbed by a thermodynamic system during a change of state that occurs without a change in temperature. Such a process may be a phase transition, such as, the melting of ice or the boiling of water.
Specific heat: Specific heat is the amount of energy that has to be transferred to or from one unit of mass (kilogram) or amount of substance (mole) to change the system temperature by one degree. Specific heat is a physical property, which means that it depends on the substance under consideration and its state as specified by its properties. Entropy: Entropy is defined as quantities to facilitate the quantification and measurement of heat flow through a thermodynamic boundary. Temperature: The Units of Temperature includes Celsius, Fahrenheit, Kelvin and Rankin. Temperature (thermodynamic temperature) is a measure of the average kinetic energy of systems particles. Temperature is the degree of "hotness" or "coldness", a measure of the heat intensity. When two objects of different temperatures are in contact, the warmer object becomes colder while the colder object becomes warmer. It means that heat flows from the warmer object to the colder one. A thermometer can help us determine how cold or how hot a substance is. Temperatures are measured and reported in degrees Celsius (0C) or degrees Fahrenheit (0F), Kelvin (K) and Degree Rankin (R). The Celsius and Fahrenheit scales of the temperature at which ice melts or water freezes and the temperature, at which water boils, are used as reference points. On the Celsius scale, the freezing point of water is defined as 0 0C, and the boiling point of water is defined as 100 0C. On the Fahrenheit scale, the water freezes at 32 0F and the water boils at 212 0F. On the Celsius scale there are 100 degrees between freezing point and boiling point of water, compared to 180 degrees on the Fahrenheit scale. This means that 1 0C = 1.8 0F. Thus the following formulas are used to convert temperature between the two scales: t 0F = 1.8 t 0C + 32 = 9/5 t 0C + 32 and T 0C = 0.56 (t 0F - 32) = 5/9 (t 0F - 32). Where, t 0C = temperature (0C) and t 0F = temperature (0F). Kelvin (K):. On the Kelvin or the Absolute Temperature Scale the coldest temperature possible is -273 0C, and has a value of 0 Kelvin (0 K) and is called the absolute zero. Units on the Kelvin scale are called Kelvin's (K) and no degree symbol is used. There are no lower temperatures than 0 K on the Kelvin or the Absolute Temperature Scale. The Kelvin scale does not have negative numbers. A Kelvin equal in size to a Celsius unit, such as 1 K = 1 0C. To calculate a Kelvin temperature, add 273 to the Celsius temperature: t K = t 0C + 273.16. Example: 37 0C = 37 + 273.16 = 310.16 K. Rankin (R): In the English system the absolute temperature is in degrees Rankin (R), not in Fahrenheit. t R = t F + 459.67. Example: 37 0F = 37 + 459.67 = 496.67 R. Thermal conductivity: Thermal conductivity, k, is the property of a material's ability to conduct heat. Heat transfer across materials of high thermal conductivity occurs at a faster rate than across materials of low thermal conductivity. Materials of low thermal conductivity are used as thermal insulation. Thermal conductivity of materials is temperature dependent. In general, materials become more conductive to heat as the average temperature increases. The reciprocal of thermal conductivity is thermal resistance.
Units of thermal conductivity:In the International System of Units (SI), thermal conductivity is measured in watts per meter Kelvin {W/(m·K)}. In the imperial system of measurement thermal conductivity is measured in Btu/(hr·ft ⋅ F). Where 1 Btu/(hr·ft ⋅ F) = 1.730735 W/(m·K). This is a list of approximate values of thermal conductivity, k, for some common materials.
Table 2: Thermal conductivity of Materials Material Air Wood Rubber Cement, Portland Epoxy (silica-filled) Water (liquid) Thermal grease Thermal epoxy Glass Soil Concrete, stone Ice Sandstone Mercury Stainless steel Lead Aluminium Gold Copper Silver Diamond
Thermal conductivity [W/(m·K)] 0.025 0.04 - 0.4 0.16 0.29 0.30 0.6 0.7 - 3 1-7 1.1 1.5 1.7 2 2.4 8.3 12.11 ~ 45.0 35.3 237 (pure) 120—180 (alloys) 318 401 429 900 - 2320
Thermal Resistance: The reciprocal of thermal conductivity is thermal resistance, usually measured in Kelvin-meters per watt (K·m·W−1). Sound: A sound is produced when the membrane of the sounding instrument vibrates. Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations. Propagation of sound: Sound is a sequence of waves of pressure that propagates through compressible media such as air or water. (Sound can propagate through solids as well, but there are additional modes of propagation). During propagation, waves can be reflected, refracted, or attenuated by the medium. Speed of sound: The speed of sound depends on the medium the waves pass through, and is a fundamental property of the material. In general, the speed of sound is proportional to the square root of the ratio of the elastic modulus (stiffness) of the medium to its density. Those physical properties and the speed of sound change with ambient conditions. Example: The speed of sound in gases depends on temperature. In 20 °C (68 °F) air at the sea level, the speed of sound is approximately 343 m/s (1,230 km/h; 767 mph) using the formula "v = (331 + 0.6 T) m/s". In fresh water, also at 20
°C, the speed of sound is approximately 1,482 m/s (5,335 km/h; 3,315 mph). In steel, the speed of sound is about 5,960 m/s (21,460 km/h; 13,330 mph). Acoustics: Acoustics is the interdisciplinary science that deals with the study of all mechanical waves in gases, liquids, and solids including vibration, sound, ultrasound and infrasound. The application of acoustics is the audio and noise control industries. Noise: Noise is a term often used to refer to an unwanted sound. Noise is an undesirable component that obscures a wanted signal. Sound pressure level: Sound pressure level is the difference, in a given medium, between average local pressure and the pressure in the sound wave. Example: 1 Pa RMS sound pressure (94 dBSPL) in atmospheric air implies that the actual pressure in the sound wave oscillates between (1 atm Pa) and (1 atm Pa), that is between 101323.6 and 101326.4 Pa. Sound frequency: An audio (Sound) frequency (abbreviation: AF) or audible frequency is characterized as a periodic vibration whose frequency is audible to the average human. It is the property of sound that most determines pitch and is measured in hertz (Hz). The generally accepted standard range of audible frequencies is 20 to 20,000 Hz, Table 3: Sound Characteristic Frequency (Hz) 16 to 32 32 to 512 512 to 2048 2048 to 8192
Octave 1st 2nd to 5th 6th to 7th 8th to 9th
8192 to 16384
10th
Description human feeling level Rhythm frequencies Low speech good speech sounds of bells, ringing of cymbals, high speech Table 4: Sound Characteristic
Symbol
Units
p
Pascal's
f
hertz
ξ
m, metres
c v ρ I
m/s m/s kg/m3 W/m²
Meaning RMS sound pressure frequency particle displacement speed of sound particle velocity density of air sound intensity
Sound intensity: The term "intensity" is used exclusively for the measurement of sound in watts per unit area. Sound intensity or acoustic intensity (I) is defined as the sound power Pac per unit area A. The usual context is the noise measurement of sound intensity in the air at a listener's location.
Acoustic intensity: The intensity is the product of the sound pressure and the particle velocity, ; Notice that both v and I are Vectors, which means that both have a direction as well as a magnitude. Elasticity: Elasticity is the physical property of a material due to which it returns to its original shape after the stress or external forces is removed. Stress: Stress is the measures of the average force per unit area of a surface on which internal forces act. Yield Strength: The yield strength of a material is the stress at which a material begins to deform plastically. Stress–strain curve: The stress–strain curve is a graphical representation of the relationship between stress and strain, by measuring the deformation of the sample, i.e. elongation, compression, or distortion. Young's modulus: The slope of the stress-strain curve at any point is called the tangent modulus. The tangent modulus of the initial, linear portion of a stress-strain curve is called Young's modulus, also known as the tensile modulus. It is defined as the ratio of the unit-axial stress over the unit-axial strain in the range of stress in which Hooke's Law holds. It is a measure of the stiffness of an elastic material Young's modulus Units: Young's modulus is the ratio of stress to strain and so Young's modulus has units of pressure. (Stress (σ) is shown as a function of strain (ε). 1= True elastic limit; 2= Proportionality limit; 3= Elastic limit and 4= Offset yield strength.) Hooke's law: Hooke's law of elasticity states that the extension of a spring is in direct proportion with the load applied to it as long as the load does not exceed the material's elastic limit. Mathematically, Hooke's law states that:
Where, x is the displacement of the spring; F is the restoring force exerted; and k is a constant called the rate or spring constant. Strain: The relative amount of deformation is called the strain.
Fig: Stress–strain curve for nonferrous alloys.
Physical Properties of Materials: Properties of common solid materials are divided into following categories: (1) Physical Properties, such as, density, melting and boiling temperature; (2) Mechanical Properties, such as, elastic modulus, shear modulus, poison's ratio, and mechanical strength, i.e., yielding stress, ultimate stress, elongation; (3) Thermal Properties, such as, coefficient of thermal expansion, thermal conductivity; (4) Electric Properties, such as, electric resistivity and conductivity; and (5) Acoustic Properties, such as, compression wave velocity, shear wave velocity, bar velocity. Properties are given at 1 atm (1.01325×105 Pa; 760 mmHg; 14.6959 psi) and at room temperature 25 ºC (77 ºF) unless specified otherwise. Table 5: Physical Properties of Solid Materials Material Density Melting Boiling (Solid) (×1000 Point Point kg/m3) (ºC) (ºC) Aluminium [Al] 2.71 660.3 2519 Brass 8.4 - 8.75 930.0 Carbon [C] 2.25 4492 3642 Copper [Cu] 8.94 1085 2562 Copper Alloy 8.23 925.0 Iron [Fe] 7.87 1538 2861 Iron (Cast) 7 - 7.4 Iron (Wrought) 7.4 - 7.8 Lead [Pb] 11.3 327.5 1749 Magnesium [Mg] 1.74 650.0 1090 Magnesium Alloy 1.77 1246 2061 Monel (67% Ni, 30% Cu) 8.84 1330 Nickel [Ni] 8.89 1455 2913 Nylon; Polyamide 1.1 Rubber 0.96 - 1.3 Silicon [Si] 2.33 1382 Steel 7.85 1425 Titanium [Ti] 4.54 1668 3287 Titanium Alloy 4.51 Tungsten [W] 19.3 3422 5555 Zinc [Zn] 7.14 419.5 907.0 Mercury [Hg] (20 ºC) 13.57904 -38.83 356.7 Water; Distilled [H2O] (20 0.998 0 100.0 ºC) Water; Sea (13 ºC) 1.024 Air (25 ºC, dry) 0.001184 Argon [Ar] (0 ºC) 0.001784 -189.3 -185.8 Carbon Dioxide [CO2] (0 -56.57 ºC)
Helium [He] (0 ºC) 0.0001785 Hydrogen [H2] (0 ºC) 8.99 Nitrogen [N2] (0 ºC) 0.00125 Oxygen [O2] (0 ºC) 0.001429 Water; Steam [H2O] (100 0.6 ºC)
-259.3 -210.0 -218.8
-268.9 -252.9 -195.8 -182.9
-
-
Table 6: Mechanical Properties of Solid Materials Elastic Shear Material Poisson's Modulus Modulus (Solid) Ratio (GPa) (GPa) Aluminium Alloy 70 - 79 26 - 30 0.33 Brass 96 - 110 36 - 41 0.34 Carbon [C] 6.9 Copper Alloy 120 47 Iron (Cast) 83 - 170 32 - 69 0.2 - 0.3 Iron (Wrought) 190 75 0.3 Magnesium [Mg] 41 15 0.35 Monel (67% Ni, 170 66 0.32 30% Cu) Nickel [Ni] 210 80 0.31 7.0 × 10-4 2.0 × 10-4 Rubber 0.45 - 0.5 - 4.0 × 10- 1.0 × 10-3 3
Titanium [Ti] Zinc [Zn]
110 -
40 - 40 -
0.33 0.25
Table 7: Mechanical Properties of Solid Materials Material Yield Ultimate Elongation (Solid) Stress Stress (%) (MPa) (MPa) Aluminium [Al] 20 70 60 Aluminium Alloy 35 - 500 100 - 550 1 - 45 Brass 70 - 550 200 - 620 4 - 60 Brass 170 - 410 410 - 590 15 - 50 Brass; Red (80% Cu, 90 - 470 300 - 590 4 - 50 20% Zn) Bronze; Regular 82 - 690 200 - 830 5 - 60 Copper [Cu] 55 - 330 230 - 380 10 - 50 Copper Alloy 760 830 4 Iron (Cast) 120 - 290 69 - 480 0-1
Iron (Wrought) Magnesium [Mg] Magnesium Alloy Monel (67% Ni, 30% Cu) Nickel [Ni] Rubber Titanium [Ti] Titanium Alloy
210 20 - 70 80 - 280 170 1100 140 - 620 1.0 - 7.0 -
Tungsten [W]
-
35 5 - 15 2 - 20
450 - 1200 2 - 50 310 - 760 7.0 - 20 500 900 - 970 1400 4000
2 - 50 100 - 800 25 10 0-4
Table 8: Properties of Solid Materials Thermal Density Elastic Heat Poisson's Conductivity (kg/m^3) Modulus capacity ratio (W/m C) (Pa) (J/kg C)
Material
Aluminium 2024T3 Aluminium 6061T6 Aluminium 7079T6 Copper - pure Iron MagnesiumHK3124 MagnesiumAZ3124 Molybdenum Nickel PTFE Silver Steel AISI304 Steel AISIC1020 Tantalum Titanium B120VCA Tungsten
Material
340 100 - 170 140 - 340
190.40
2770
7.310E+10 963.00
0.3300
155.80
2700
7.310E+10 963.00
0.3300
121.10
2740
7.172E+10 963.00
0.3300
392.90 83.50
8900 7830
385.00 440.00
114.20
1790
4.414E+10 544.0
0.3500
95.19
1770
1047
0.3500
143.60 91.73 0.2400 417.10 16.27 46.73 53.65
1.030E+04 8900 1200 1.050E+04 8030 7850 1.660E+04
2.759E+11 293.0 2.207E+11 2453 7.241E+10 235.0 1.931E+11 503.0 2.034E+11 419.0 1.862E+11 126.0
0.3200
7.4420
4850
1.021E+11 544.0
0.3000
164.40
1.930E+04 3.448E+11 138.0
0.2800
0.3700 0.2900 0.2900 0.3500
Table 9: Acoustic Properties of Solid Materials Longitudinal Shear Wave Bar Wave Velocity Velocity
(Solid) Aluminium [Al] (Rolled) Brass Brick
Velocity (m/s) 6420 4700 -
(m/s)
(m/s)
3040 2110 -
5000 3480 3650 3810 / 3750 500.0 1190 / 1210 1800 5200 3810 2730 4670 / 1260 3850
Copper [Cu] (Annealed/Rolled) 4760 / 5010
2325 / 2270
Cork
-
-
Lead [Pb] (Annealed/Rolled)
2160 / 1960
700.0 / 690.0
Nylon; Polyamide Rubber Steel Stone; Marble Tin [Sn]
2620 1550 - 1830 5960 3320
1070 3235 1670
Wood; Ash
-
-
Wood; Oak
-
-
Table 10: Mechanical Properties of Liquid & Gas Materials Bulk Kinematic Viscosity Material Modulus Viscosity (Pa-s) (GPa) (m2/s) Acetone [C3H6O] (20 ºC) 0.389 × 10-3 Alcohol; Ethanol [C2H5OH] (20 0.823 1.77 × 10-3 2.20 × 10-6 ºC) Alcohol; Methanol [CH3OH] (20 0.902 0.817 × 10-3 1.01 × 10-6 ºC) Mercury [Hg] (20 ºC) 25.3 1.55 × 10-3 0.114 ×10-6 Oil; Lubricating (20 ºC) 799 × 10-3 900 × 10-6 Water; Distilled [H2O] (20 ºC) 2.18 1.00 × 10-3 1.00 × 10-6 Water; Distilled [H2O] (25 ºC) 1.57 × 10-3 1.57 × 10-6 Water; Distilled [H2O] (4 ºC) 2.28 Water; Sea (13 ºC) 0.017 × 10-3 13.3 × 10-6 Air (0 ºC, dry) 0.0179 × 10-3 14.6 × 10-6 Carbon Dioxide [CO2] (0 ºC) 0.0138 × 10-3 Helium [He] (0 ºC) 0.0186 × 10-3 Hydrogen [H2] (0 ºC) 0.0084 × 10-3 Nitrogen [N2] (0 ºC) 0.0166 × 10-3 Oxygen [O2] (0 ºC) 0.0192 × 10-3 -
Table 11: Physical Properties of Liquid Materials Density Melting Boiling Material (×1000 Point Point (Liquid) kg/m3) (ºC) (ºC) Acetone [C3H6O] (20 ºC) 0.7899 -94.85 56.05 Alcohol; Ethanol [C2H5OH] 0.789 -114.2 78.29 (20 ºC) Alcohol; Methanol [CH3OH] (20 0.792 -97.68 64.55 ºC) Mercury [Hg] (20 ºC) 13.57904 -38.83 356.7 Oil; Mineral 0.92 Oil; Olive 0.92 -6.00 Oil; Petroleum 0.82 Water; Distilled [H2O] (20 ºC) 0.998 0 100.0 Water; Distilled [H2O] (25 ºC) 0.997 0 100.0 Water; Distilled [H2O] (4 ºC) 1 0 100.0 Water; Sea (13 ºC) 1.024 Table 12: Thermal Properties of Liquid Thermal Thermal Expansion Material Conductivity Coefficient (W/m·K) (×10-6/ºC) Acetone [C3H6O] (20 ºC) 0.161 Alcohol; Ethanol [C2H5OH] (20 0.169 ºC) Alcohol; Methanol [CH3OH] (20 0.200 ºC) Mercury [Hg] (20 ºC) 182 8.25 Water; Distilled [H2O] (20 ºC) 207 Water; Distilled [H2O] (25 ºC) 0.607 Altitude and Air Pressure & Specific Volume Correction Factors: The air pressure varies with altitude. The specific volume of standard air at a certain altitude can be calculated by multiplying with the volume correction factor below: Table 13: Altitude and Air Pressure & Specific Volume Altitude Air Volume Altitude Air Volume (Meter) Pressure Correction (Meter) Pressure Correction (psia) Factor (psia) Factor
0 500 1000 1500 2000 3000
14.7 13.74 13.29 12.12 11.52 10.15
1.00 1.06 1.11 1.19 1.25 --
4000 5000 6000 7000 8000 9000
8.92 7.83 6.82 5.96 5.17 4.46
-------
Air: Air is a mixture of gases, such as 78% nitrogen and 21% oxygen with traces of water vapour, carbon dioxide, argon, and various other components as given in Table: Table 14: Properties of Air Ratio (%) Molecular (Volume) Mass (kg/kmol) 20.95 23.20 78.09 75.47 0.03 0.046
Gas
Oxygen Nitrogen Carbon Dioxide Hydrogen Argon Neon Helium Krypton Xenon
0.00005 0.933 0.0018 0.0005 0.0001 9 10-6
~0 1.28 0.0012 0.00007 0.0003 0.00004
Chemical Symbol O2 N2 CO2 H2 Ar Ne He Kr Xe
Table 15: Physical Constants in SI units Symbol Value (SI Unit)
Quantity Bohr magnetron Bohr radius characteristic impedance of vacuum classical electron radius conductance quantum Coulomb's constant electric constant
9.274 009 68 × 10−24 J·T−1 5.291 772 1092 × 10−11 m 376.730 313 461... Ω
2.817 940 3267 × 10−15 m 7.748 091 7346 × 10−5 S 8.987 551 N·m²·C−2
787...
×
109
(vacuum permittivity) electron mass elementary charge Fermi coupling constant Harte energy inverse conductance quantum Josephson constant magnetic constant (vacuum permeability) magnetic flux quantum Newtonian constant of gravitation nuclear magnetron Planck constant proton mass quantum of circulation reduced Planck constant Rydberg constant second radiation constant speed of light in vacuum Stefan– Boltzmann
8.854 187 817... × 10−12 F·m−1 9.109 382 91 × 10−31 kg 1.602 176 565 × 10−19 C 1.166 364 × 10−5 GeV−2 4.359 744 34 × 10−18 J 12 906.403 7217 Ω 4.835 978 70 × 1014 Hz·V−1 4π × 10−7 N·A−2 = 1.256 637 061... × 10−6 N·A−2 2.067 833 758 × 10−15 Wb 6.67384(80)×10−11 m3·kg−1·s−2 5.050 783 53 × 10−27 J·T−1 6.626 069 57(29) × 10−34 J·s 1.672 621 777 × 10−27 kg 3.636 947 5520 × 10−4 m² s−1 1.054 571 726(47) × 10−34 J·s 10 973 731.568 539 m−1 1.438 7770 × 10−2 m·K 299 792 458 m·s−1 5.670 373 × 10−8 W·m−2·K−4
constant Thomson cross section von Klitzing constant
6.652 458 734 × 10−29 m² 25 812.807 4434 Ω
Table 16: Astronomical constants in SI units Acceleration Sea level 9.8067 m/s2 Luminosity Sun 3.826E+26 J/s Mass Sun 1.989E+30 kg Mass Earth 5.976E+24 kg Pressure Sea level 1.013E+05 Pa Radius Earth 6.371E+06 m Radius Sun 6.970E+08 m Velocity Earth's orbital 2.978E+04 m/s
1.4
Hydraulic engineering
Hydraulics Engineering deals with the mechanical properties of liquids or fluid at rest. Fluids exert pressure normal to any contacting surface. Fluids at rest indicate that there exists a force, known as pressure that acts upon its surroundings. This pressure is not constant throughout the body of fluid. Pressure, ‘p’, increases with an increase in depth. Where the upward force on a body acts on the base and can be found by equation: , Where h is the height of the liquid column; ρ is liquid the constant and g = specific gravity. Archimedes Law of Buoyancy: Discovery of the principle of buoyancy is attributed to Archimedes. When anybody of arbitrary shape is immersed, partly or fully, in a fluid, it will experience the action of a net force in the opposite direction of the local pressure gradient. If this pressure gradient arises from gravity, the net force is in the vertical direction opposite that of the gravitational force. This vertical force is termed buoyancy or buoyant force and is equal in magnitude, but opposite in direction, to the weight of the displaced fluid. Example: In the case of a ship, its weight is balanced by shear force from the displaced water allowing it to float. If more cargo is loaded onto the ship, it would sink more into the water displacing more water and thus receive a higher buoyant force to balance the increased weight. Properties of perfect gases (Ideal gas): A perfect gas (or an ideal gas) is a state of a substance, whose evaporation from its liquid state is complete. Laws of perfect gas: The physical properties of a gas are controlled by the following three variables: (i) Pressure exerted by the gas. (ii) Volume occupied by the gas. (iii) Temperature of the gas. Avogadro's law: Avogadro's law is stated mathematically as: Where, V is the volume of the gas. n is the amount of substance of the gas. k is proportionality constant. Molar volume: Taking STP to be 101.325 kPa and 273.15 K, we can find the volume of one mole of a gas:
For 100.000 kPa and 273.15 K, the molar volume of an ideal gas is 22.414 dm3 mol-1. Boyle's law: Boyle’s law is relation to Kinetic Theory and Ideal Gases and states that at constant temperature for a fixed mass, the absolute pressure and the volume of a gas are inversely proportional. The law can also be stated in a slightly different manner, that the product of absolute pressure and volume is always constant. The mathematical equation for Boyle's law is: 1 P P V = constant
OR; or, P1 V1 = P2 V2 = P3 V3 = k
V
Where, p denotes the pressure of the system; V denotes the volume of the gas; k is a constant value representative of the pressure and volume of the system and 1, 2, 3 refer to the different sets of conditions. Examples: The Change of Pressure in a Syringe, the popping of a Balloon, increase in size of bubbles as they rise to the surface, death of deep sea creatures due to change in pressure and popping of ears at high altitude are the examples. Charles's law: Charles's law states that at constant pressure, the volume of a given mass of an ideal gas increases or decreases by the same factor as its temperature on the absolute temperature scale (i.e. the gas expands as the temperature increases). This can be written as, Where V is the volume of the gas; and T is the absolute temperature. The law can also be usefully expressed as follows:
The equation shows that as absolute temperature increases, the volume of the gas increases in proportion at a constant pressure. Relation to the ideal gas law: French physicist Emile Clapeyron combined Charles's law with Boyle's law to produce a single equation which would become known as the ideal gas law:
Where, t is the Celsius temperature; and p0, V0 and t0 are the pressure, volume and temperature of a sample of gas under some standard state. The figure of 267 came directly from Gay-Lussac's work. The modern figure would be 273.15. For any given sample of gas, p0 V0 ⁄ 267+ t0 is a constant (Clapeyron denoted this constant R, and it is closely related to the modern gas constant); if the pressure is also constant, the equation simplifies to
The thermodynamic properties of an ideal gas law are:
Where, P is the pressure; V is the volume; n is the amount of substance of the gas (in moles); R is the gas constant (8.314 J·K−1mol-1) and T is the absolute temperature Absolute Zero: Charles's law appears to imply that the volume of a gas will descend to zero at a certain temperature (−266.66 °C according to Gay-Lussac's figures) or -273°C. However, the "absolute zero" on the Kelvin temperature scale was originally defined in terms of the second law of thermodynamics. Relation to kinetic theory: Where, N is the number of molecules in the gas sample. If the pressure is constant, the volume is directly proportional to the average kinetic energy and hence to the temperature for any given gas sample. The kinetic theory of gases relates that the temperature being
proportional to the average kinetic energy of the gas molecules. The kinetic theory equivalent of the ideal gas law relates pV to the average kinetic energy: iii) General Gas Equation: In order to deal with all practical cases, the Boyles’ law and Charles’ law are combined together, which give us a general gas equation as below; P1 V1 = T1
P2 V2 P3 V3 = = ……. = Constant T2 T3
Viscous Flow: A viscous fluid will deform continuously under a shear force, whereas an ideal fluid doesn't deform. Both pneumatics and hydraulics are applications of fluid power. Pneumatics fluid is an easily compressible, such as, gas or air, while hydraulic fluid is relatively incompressible liquid media such as water or oil. Most industrial applications of pneumatic fluid pressures are about 80 to 100 pounds per square inch (550 to 690 kPa). Hydraulics applications commonly use from 1,000 to 5,000 psi (6.9 to 34 MPa) with specialized applications up to 10,000 psi (69 MPa). Hydraulic systems use an incompressible fluid, such as oil or water, to transmit forces from one location to another within the fluid. Most aircraft use hydraulics in the braking systems and landing gear. Pneumatic systems use compressible fluid, such as air, in their operation. Some aircraft utilize pneumatic systems for their brakes, landing gear and movement of flaps. Pascal's law: Pascal's law states that when there is an increase in pressure at any point in a confined fluid, there is an equal increase at every other point in the container. There is an increase in pressure as the length of the column of liquid increases, due to the increased mass of the fluid above. Pascal's law allows forces to be multiplied. Affinity laws: The affinity laws are used in hydraulics and HVAC to express the relationship between variables involved in pump or fan and turbine performance, such as, head, flow rate, shaft speed, and power. In rotary implements, the affinity laws apply both to centrifugal and axial flows. The affinity laws are useful as they allow prediction of the head discharge characteristic of a pump or fan from a known characteristic measured at a different speed or impeller diameter. Quantity of Discharge through a pipe = Q = Cross Section Area of Pipe x Velocity = A V, Where, V = C rS and, C = 2 g / ----------------------------------------------------(i) = 0.01 (1+1 / 12 d) for old pipes. And, = 0.005 (1+1 / 12 d) for new pipes. -----------(ii) Where d is the inside diameter of pipe. Pipe Friction:
h f= 4
L V2 / 2 g d; Where,
= 0.0056; and d = H. M. D. =Inside diameter of pipe ----(iii)
For old pipes Velocity = V = 39 S Inside Diameter = d = 0.2545 x 5 Q2 /g
For new pipes d
Velocity = V = 55
d
S Inside Diameter = d = 0.222 x 5 Q2 /g
Loss of head in pipe: Head loss is calculated with,
Where, hf is the head loss due to friction (SI units: m); L is the length of the pipe (m); D is the hydraulic diameter of the pipe (for a pipe of circular section, this equals the internal diameter of the pipe) (m); V is the average velocity of the fluid flow, equal to the volumetric flow rate per unit crosssectional wetted area (m/s); g is the local acceleration due to gravity (m/s2); f is a dimensionless coefficient called the Darcy friction factor. It can be found from a Moody Diagram or more precisely by solving the Colebrook Equation. Pressure loss: The head loss hf expresses the pressure loss Δp as the height of a column of fluid,
Where ρ is the density of the fluid, the Darcy–Weisbach equation can also be written in terms of pressure loss:
Where the pressure loss due to friction Δp (units: Pa or kg/ms2) is a function of: the ratio of the length to diameter of the pipe, L/D; the density of the fluid, ρ (kg/m3); the mean velocity of the flow, V (m/s), as defined above; a (dimensionless) coefficient of laminar, or turbulent flow, f. Components of hydraulic head: A mass free falling from an elevation (in a vacuum) will reach a speed,
When Where, g is the acceleration When arriving at elevation z = 0 or when we rearrange it as a due to gravity. head. Head Loss due to Sudden
Head Loss due to Sudden
Enlargement
Contraction
Head Loss = (V1 - V2) 2 / 2g
Head Loss = 0.5 V22 / 2g
Head Loss due to Obstruction
Head Loss due to Change of direction
Head Loss = A / Cc (AQ) - 1 x V22 / 2g
Head Loss = K V22 / 2g; For 900 bend K = 1. Where, K depends upon bend type.
Bernoulli’s Theorem: For a non-viscous, incompressible fluid in steady flow, the sum of pressure, potential and kinetic energies per unit volume is constant at any point. A centrifugal pump converts the input power to kinetic energy in the liquid by accelerating the liquid by a revolving device - an impeller. The energy created by the pump is kinetic energy according the Bernoulli Equation. The energy transferred to the liquid corresponds to the velocity at the edge or vane tip of the impeller. The faster the impeller revolves or the bigger the impeller is the higher will the velocity of the liquid energy transferred to the liquid be. This is described by the Affinity Laws. A special form of the Euler’s equation derived along a fluid flow streamline is often called the Bernoulli Equation:
Where, v = flow speed; p = pressure; ρ = density; g = gravity; h = height.
H = h + V2 / 2g + P / W Total energy = E pot + E kin + E press Specific energy = Static energy + Kinetic energy.
Depth for minimum energy is called critical path.
E = d + V2 / 2g
V2= g x d; Frauds number = V/ g d
Kennedy’s Equation for Critical Velocity at top of channel = Vo = C x Dn ft/sec Where, C = 0.84; n = 0.64; and D = depth of channel.
1.5
Chemistry
Chemistry is the science of study of interaction of chemical substances, such as, the composition, behaviour, reaction, structure, and properties of atoms, the subatomic particles, protons, electrons and neutrons, molecules or crystals and the changes it undergoes. These include inorganic chemistry; organic chemistry; biochemistry; physical chemistry; and analytical chemistry. Chemical Substance: A chemical substance is a mixture of compounds, elements. Example: air, alloys, biomass, etc. Compound: A compound is a substance with a particular ratio of atoms of particular elements which determines its composition, and chemical properties. Example: water is a compound containing hydrogen and oxygen in the ratio of two to one, with one oxygen atom between the two hydrogen atoms. Compounds are formed by chemical reactions. Inorganic Compound: Inorganic compounds are considered to be of a mineral with no biological origin. Organic compound: An organic compound is chemical compounds whose molecules contain carbon. Methane is one of the simplest organic compounds. Molecule: A molecule is the smallest indivisible portion of a pure chemical substance that has its unique set of chemical properties and its potential to undergo a certain set of chemical reactions with other substances. Molecules are typically a set of atoms bound together by covalent bonds and electrically neutral. All valence electrons are paired with other electrons either in bonds or in lone pairs. One of the main characteristic of a molecule is its geometry often called its structure. Mole: Mole is a SI Unit to measure amount of substance (chemical amount). A mole is the amount of a substance that contains as many elementary entities as there are atoms in 0.012 kilogram (or 12 grams) of carbon-12, where the carbon-12 atoms are unbound, at rest and in their ground state. Element: The element is a particle which is composed of a single atom and is associated by a particular number of protons in the nuclei of its atoms. It is known as the atomic number of the element. Example: All atoms have 6 protons in their nuclei in the chemical element carbon, and all atoms have 92 protons in their nuclei in the element uranium. Ninety–four different chemical elements exist naturally and another 18 have been recognized as existing artificially only. All the nuclei of all atoms of one element will have the same number of protons, but they may not necessarily have the same number of neutrons and such atoms are termed isotopes. In fact several isotopes of an element may exist. Some Chemical Elements are given in the periodic table, which is grouped by atomic number. Atom: The atom is the smallest entity of the chemical substance that retains the chemical properties of the element, such as electro negativity, ionization potential, preferred oxidation state, coordination number, and types of bonds e.g. metallic, ionic or covalent. An atom is the basic unit of chemistry, which consists of a positively charged core called the atomic nucleus, which contains protons and neutrons, and maintains a number of electrons to balance the positive charge in the nucleus. The atoms belonging to one element will have the same number of protons in all the particles of that Element, but they may not necessarily have the same number of neutrons and thus are termed isotopes. Atomic Number: The element is composed of a single atom with a particular number of protons in its nuclei, which is called the Atomic Number of the Element. Example: carbon has 6 protons in nuclei of their atoms of the element and thus the Atomic Number is 6. In an atom of neutral charge, the number of electrons typically equals the atomic number.
Atomic mass unit: The atomic mass unit (amu) or unified atomic mass unit (u) or Dalton (Da), is a small unit of mass used to express the atomic masses and molecular masses. It is defined to be 1/12 of the mass of one atom of Carbon-12. Accordingly, 1 u = 1/NA gram = 1/(1000 NA) kg (where NA is Avogadro's number) = 1.66053886 x 10-27 kg Pico metre: Pico metre (pm) is a measure of length that is commonly used in measuring the atomicscale distances or the atom diameters, which are in the range from approximately 30 to 600 pm. 1 pm = 1 × 10−12 metre. 1 pm = 1000 femtometre. 100 pm = 1 angstrom. 1000 pm = 1 nanometre. 1 nm = 1000. Nucleus: The nucleus of most atoms consists of protons and neutrons. As exception, the Isotope of Hydrogen consists of a single proton without any neutron. Outside the nucleus, neutrons are unstable and have a mean lifetime of 886 seconds (15 minutes), decaying by emitting an electron and antineutrino to become a proton. Neutrons in this unstable form are known as free neutrons. Particles inside the nucleus are in resonances between neutrons and protons, which transform into one another by the emission and absorption of Pions. Proton: The Proton is a subatomic particle with an electric charge of one positive fundamental unit (1.602 × 10−19 coulomb) and a mass of 938.3 MeV/c2 (1.6726 × 10−27 kg, or about 1836 times the mass of an electron). The proton is observed to be stable, with a lower limit on its half-life of about 1035 years, although some theories predict that the proton may decay. The nuclei of the atoms are composed of protons and neutrons held together by the strong nuclear force. The number of protons in the nucleus determines the chemical properties of the atom or the chemical element. Protons are classified as Baryons and are composed of two “up quarks” and one “down quark”, which are also held together by the strong nuclear force, mediated by Gluons. The proton's antimatter equivalent is the antiproton, which has the same magnitude charge as the proton but the opposite sign. Because the electromagnetic force magnitude is stronger than the gravitational force, the charge on the Proton is equal and opposite of the charge on the Electron. Otherwise, the net repulsion of having an excess of positive or negative charge would cause an expansion effect on the universe, and indeed any gravitationally aggregated matter like planets or stars. Neutron: The Neutron is a subatomic particle with no net electric charge and a mass of 939.6 MeV/c² (kg, slightly more than a proton). Its spin is ½. A neutron is classified as a baryon and consists of two “down quarks” and one “up quark”. The neutron's antimatter equivalent is the antineutron. Proton Mass 938 MeV/c² Electric Charge 1.6 × 10−19 C Spin 1/2 Quark 1 Down, 2 Up Composition
Neutron Mass: 940 MeV/c² Electric charge: 0 C Spin: ½ Quark 2 Down, 1 Up composition:
Ions and Salts An ion is a charged atom or molecule that has lost or gained one or more electrons. Positively charged cations (e.g. sodium cation Na+) and negatively charged anions (e.g. chloride anion Cl−) can form a crystalline lattice of neutral salts (e.g. sodium chloride NaCl). The polyatomic ions that do not split up during acid-base reactions are hydroxide (OH−) and phosphate (PO43−). Ions in the gaseous phase are often known as plasma.
Acid and Base: An acid is a substance that produces hydronium ions when it is dissolved in water, and a base is one that produces hydroxide ions when dissolved in water. Acids donate a positive hydrogen ion to another substance in a chemical reaction. A base receives the hydrogen ion. An acid is a substance which is capable of accepting a pair of electrons from another substance during the process of bond formation, while a base can provide a pair of electrons to form a new bond. Oxidants & Reductant: It is a concept related to the ability of atoms of various substances to lose or gain electrons. Substances that have the ability to oxidize other substances are said to be oxidative and are known as oxidizing agents, oxidants or oxidizers. An oxidant removes electrons from another substance. Similarly, substances that have the ability to reduce other substances are said to be reductive and are known as reducing agents, reductants, or reducers. A reductant transfers electrons to another substance, and is thus oxidized itself. Chemical Equilibrium: Chemical Equilibrium is a stage of chemical reaction when the chemical composition of the substance remains unchanged over time. Chemical laws: Chemical reactions are governed by certain laws, which have become fundamental concepts in chemistry. Some of them are: Avogadro’s law; Beer-Lambert law; Boyle’s law (relating pressure and volume); Charles’s law (relating volume and temperature); Fick’s law of diffusion; GayLussac’s law (relating pressure and temperature); Le Chatelaine’s Principle; Henry’s law; Hess’s Law; Law of conservation of energy; Law of conservation of mass; Law of definite composition; Law of multiple proportions and Fault’s Law. Conservation of energy: The law of conservation of energy states that the total amount of energy in a system remains constant over time. A consequence of this law is that energy can neither be created nor destroyed. It can only be transformed from one state to another. Einstein’s theory of relativity: Albert Einstein’s theory of relativity states that mass is a form of energy and can transform one into another with the conservation of the total energy of a system to other system of energy. The first law of thermodynamics: Entropy is a function of a quantity of heat which shows the possibility of conversion of that heat into work. Conservation of mass: The law of conservation of mass states that the mass of a closed system will remain constant over time because of a result of processes acting inside the system. The mass cannot be created or destroyed, although it may be rearranged in space and changed into different types of particles for any chemical process in a closed system. The mass of the reactants must be equal to the mass of the products. Biomass: Biomass is a renewable energy source and is a biological material from living or recently living organisms, such as, wood, waste, hydrogen gas and alcohol fuels. Biomass is commonly plant matter grown to generate electricity or produce heat.
1.6
Mathematics
Mathematics is the concepts of calculations of quantity, structure, space, changes and the academic discipline that studies them. Mathematics is divided into smaller subcategories, such as, Geometry, Trigonometry, Menstruation and Algebra. Mathematics Constants: Log 10e= 0.434294; Log e10= 2.30259 e = Base of Natural Logarithms = 2.71828; Log 10N = Log eN x 0.4343; Log eN = Log 10N x 2.3026; I radian = 570 17’ 45’ = 57.29580; π = 3.1416; Log eπ = 0.4972.
Table 1: Special Math Constants Name N Name √13 3.60555 √π √17 4.12311 πe √19 4.35890 eπ 3√2 1.25992 eγ 3√3 1.44225 ee
Name π e γ √2 √3
N 3.14159 2.71828 0.57722 1.41421 1.73205
N 1.77245 22.45916 23.14069 1.78107 15.15426 57.29578 ° (degree) 0.01745 32925 rad
√5
2.23608
5√2
1.14870
1 rad
√7 √11
2.64575 3.31662
5√3 √e
1.24573 1.64872
1°
Greek Name Alpha Beta Gamma Delta Epsilon Zeta Eta Theta Iota Kappa Lambda Mu
Table 2: Greek Alphabet Greek Letter Greek Greek Letter Name Capital Small Capital Small Α α Nu Ν ν Β β Xi Ξ ξ Γ γ Omicron Ο ο Δ δ Pi Π π Ε ε Rho Ρ ρ Ζ ζ Sigma Σ σ&ς Η η Tau Τ τ Θ θ Upsilon Υ υ Ι ι Phi Φ φ Κ κ Chi Χ χ Λ λ Psi Ψ ψ Μ μ Omega Ω ω
Sigma σ & ς: There are two forms for the small letter Sigma. The form (ς) is written at the end of a word, called final sigma. If it occurs anywhere else, it is written like this: (σ). Arithmetic: Arithmetic is the elementary branch and involves the study of the traditional operations of
addition, subtraction, multiplication and division with smaller values of numbers.
ALGEBRA Algebra: Algebra is the branch of mathematics, which studies the rules of operations, relations, constructions and concepts arising from them, including terms, polynomials, equations and algebraic structures. An equation is a mathematical statement that asserts the equality of two expressions. Equations consist of the expressions that have to be equal on opposite sides of an equal sign, such as, Cubic Function: In mathematics, a cubic function is a function of the form
Where, ‘a’ is nonzero. The derivative of a cubic function is a quadratic function. The integral of a cubic function is a quadratic function. The coefficients a, b, c, d are real numbers. Elementary algebra: Equations involving linear or simple rational functions of a single real-valued unknown, say x, such as can be solved using the methods of elementary algebra.
Linear equation: A linear equation is an algebraic equation in which each term is either a constant or the product of a constant and the first power of a single variable. Linear equations can have one or more variables. A common form of a linear equation in the two variables x and y is,
Where, m and b are designate constants. Quadratic equation: In mathematics, a quadratic equation is a polynomial equation of the second degree. The general form is
Where, x represents a variable, and a, b, and c, constants, with a ≠ 0. The constants a, b, and c, are called respectively, the quadratic coefficient, the linear coefficient and the constant term or free term. A quadratic equation with real or complex coefficients has two solutions, called roots. These two solutions may or may not be distinct, and they may or may not be real. The roots are given by the quadratic formula
Where, the symbol "±" indicates that both are solutions of the quadratic equation. Followings are the important formulas, which is frequently being used by an engineer. Ratio:
a
c
When, = ; or a x d = b x c; or b d a+b c+d a -b c - d = ; = . b d b d Cyclic (a + b) 2 = a2 + b2 + 2 a ; (a - b) 2 = a2 + b2 - 2 a b; Expression (a - b) 2 = a2 + b2 - 2 a b; a2 - b2 = (a + b) x (a - b). a3 – b3 = (a - b) (a2 + b2 + a b) ; a3 + b3 = (a + b) (a2 + b2 - a b); (a + b) 3 = a3 + b3 + 3 a b (a + b); (a - b) 3 = a3 - b3 - 3 a b (a - b).
GEOMETRY Geometry: Geometry is all about shapes and their properties. Geometry can be divided into two parts. Plane Geometry: Plane Geometry is about flat shapes like line, plane, triangle, Quadrilateral and circles that can be drawn on a piece of paper Triangle: Triangles are assumed to be two-dimensional plane figures. A triangle is one of the basic shape of Geometry or a polygon with three corners or vertices and three sides or edges which are line segments. A triangle with vertices A, B, and C is denoted ABC. The three angles always add to 180°. A triangle that has all interior angles measuring less than 90° is an acute triangle or acuteangled triangle. A "triangle" with an interior angle of 180° and collinear vertices is degenerate. Triangle Shapes Right Angle Triangle: A right triangle has one of its interior angles measuring 90°. The side opposite to the right angle is the hypotenuse; it is the longest side of the right triangle. The other two sides are called the legs of the triangle. Scalene Triangle: Scalene Triangle has no equal sides and no equal angles. Obtuse Triangle has all three angles less than 90°. Equilateral Triangle: In
an equilateral triangle, all sides have the same length. In equilateral triangle is also a regular polygon with all angles measuring 60°. Isosceles Triangle: Isosceles triangle has two sides equal in length and two angles opposite to the two sides of the same length have same measure. Obtuse Angle Triangle: Obtuse Angle Triangle has an angle more than 90° Oblique Triangles: Triangles that has all sides different and do not have an angle that measures 90° are called oblique triangles. In diagrams representing triangles above, "tick" marks are used to denote sides of equal lengths, such as, the equilateral triangle has tick marks on all 3 sides, the isosceles on 2 sides. The scalene has single, double, and triple tick marks, indicating that no sides are equal. Similarly, arcs on the inside of the vertices are used to indicate equal angles. The equilateral triangle indicates all 3 angles are equal; the isosceles shows 2 identical angles. The scalene indicates by 1, 2, and 3 arcs that no angles are equal. Area of Triangles: The area of a triangle can be demonstrated as half of the area of a parallelogram which has the same base length and height. Simplest formula is:
Where b is the length of the base of the triangle, and h is the height or altitude of the triangle. The term 'base' denotes any side and 'height' denotes the length of a perpendicular from the vertex opposite the side onto the line containing the side itself. The sides of the triangle are known as follows: The hypotenuse is the side opposite the right angle, or defined as the longest side of a right-angled triangle, in this case h. The opposite side is the side opposite to the angle we are interested in, in this case a. The adjacent side is the side that is in contact with the angle we are interested in.
Heron's formula: The shape of the triangle is determined by the lengths of the sides alone. Therefore the area can also be derived from the lengths of the sides. By Heron's formula:
Where “s” = half of the triangle's perimeter. Three other way of finding the Triangle area by Heron's formula is:
Quadrilaterals: Quadrilateral has a four-sided two-dimensional shape. The sides are straight and the interior angles add up is equal to 360 degrees. There are many types of quadrilateral:
Rectangle: A rectangle is a four-sided shape where every angle is a right angle (90°) and opposite sides are parallel and of equal length. Rhombus: A rhombus is a four-sided shape where all sides have equal length and opposite sides are parallel and opposite angles are equal. The diagonals of a rhombus bisect each other at right angles. The Square: A square has equal sides and every angle is a right angle (90°) and opposite sides is parallel. The Parallelogram: Opposite sides are parallel and equal in length, and opposite angles are equal. Note: Squares, Rectangles and Rhombuses are all Parallelograms. Trapezoid: A trapezoid (a trapezium) has one pair of opposite sides parallel. It is called an isosceles trapezoid if the sides that aren't parallel are equal in length and both angles coming from a parallel side are equal. Circle: Circle is the set of all points on a plane that are at a fixed distance from a centre. It is a round figure. Radius and Diameter of a Circle: The Radius is the distance from the centre to the edge of the circle. The Diameter is the linear distance passing through the centre between two points on the circle, which are opposite to each other. So the Diameter is twice the Radius: Diameter = 2 × Radius. Menstruation: Menstruation is the branch of geometry dealing with measurement of geometric magnitudes such as length, area and volume. Area of a Triangle: The area of a Triangle is half of the base times height. Area = ½ b × h Where, b = base; & h = vertical height of a, b, c sides of triangle. Or, Area = √s(s-a)(s-b)(s-c); where 2s = a + b + c
Area of Squire: Square Area = a x a = a2. Where, a = length of side of the Squire. Rectangle Area = w × h, Where, w = width, h = height. Trapezoid (Trapezium) Area = ½(a+b) × h, h = vertical height. Ellipse Area = π a b. Where, a is longest diameter and b is the shortest diameter.
Parallelogram Area = b × h. Where, b = base, h = vertical height. Circle Area = πr2 Circumference=2πr =πd Where, r = radius, d=diameter of the circle.
Sector Area = ½r2θ r = radius, θ = angle radians.
in
Perimeter of Ellipse: Perimeter of Ellipse = 2π √{(a2 + b2)/2} Area of the rectangle: = w × h, Where w = width; h = height. Area of a Circle: The area of a circle is π times the Radius square or A = π × r2, or A = (π/4) × D2 Circle: A line that goes from one point to another point on the circle's circumference is called a Chord. If that line passes through the centre it is called a Diameter. If a line "just touches" the circle as it passes it is called a Tangent. And a part of the circumference is called an Arc. The slice made by a chord is called a Segment. Quarter of a circle is called a Quadrant. Half a circle is called a Semicircle.
SOLID GEOMETRY Solid Geometry: Solid Geometry is the geometry of three-dimensional space, such as, cubes, prisms and pyramids. Cube: It has 6 faces. Each face has 4 edges, and is actually a square. It has 12 edges. It has 8 corner points and at each vertex 3 edges meet. A cube is called a hexahedron because it is a polyhedron that has 6 faces. Cuboids: A cuboids is a box-shaped object having six flat sides and all angles are right angles. All of its faces are rectangles. It is also a prism because it has the same cross-section along a length. In fact it is a rectangular prism. Prisms: A prism has the same cross section all along its length. A cross section is the shape you get
when cutting straight across an object. The cross section of this object is either a triangle or square. It has the same cross section all along its length. Pyramids: A pyramid is made by connecting a base to an apex. There are many types of Pyramids, and they are named after the shape of their base. Polyhedral and Non-Polyhedral: There are two main types of solids, "Polyhedral", and "NonPolyhedral". Polyhedral must have all faces flat. Non-Polyhedral does not have any surface flat. Sphere
Torus
Cylinder
Cone
Square Pyramid: Surface Area = A + 1/2 × p x l. where p = base Perimeter and l = Slant Length of cone. Volume of Square Pyramid = 1/3 × A x h, where A = [Base Area] and h = Height. Cube: A cube of edge length ‘a’, surface area 6a2 volume a3 face diagonal space diagonal radius of circumscribed sphere radius of sphere tangent to edges radius of inscribed sphere angles between faces Volume of a cuboids: Volume of a cuboids = Height × Width × Length = V = h × w × l Surface Area of cuboids = A = 2wl + 2lh + 2hw Volume of Prisms: Volume of Prisms = Area × Length.
Triangular Pyramid: It has 4 Faces. The 3 Side Faces are Triangles. The Base is also a Triangle. It has 4 Vertices (corner points). It has 6 Edges. Volume of Pyramid = 1/3 × [Base Area] × Height. Surface Area of Pyramid: = [Base Area] + 1/2 × Perimeter × [Side Length]. (When all side faces are the same). Pentagonal Pyramid: It has 6 Faces. The 5 Side Faces are Triangles. The Base is a Pentagon. It has 6 Vertices (corner points). It has 10 Edges. Volume of Pentagonal Pyramid = 1/3 × [Base Area] × Height. Surface of Area Pentagonal Pyramid = [Base Area] + 1/2 × Perimeter × [Side Length]. (When, all side faces are the same). Cylinder: It has a flat base and a flat top. The base is the same as the top, and also in-between. It has one curved side. Because it has a curved surface it is not a polyhedron. Surface Area of Cylinder = 2 × π × r × (r+h) Surface Area of One End of Cylinder = π × r2 Surface Area of Side of Cylinder = 2 × π × r × h Volume of Cylinder = multiply the area of the circle by the height of the cylinder = = π × r2 × h. Where, Area of the circle: π × r2 and Height = h Cone: It has a flat base. It has one curved side because it has a curved surface it is not a polyhedron. A Cone is a Rotated Triangle. A cone is made by rotating a triangle. The triangle has to be a rightangled triangle, and it gets rotated around one of its two short sides. The side it rotates around is the axis of the cone. Surface Area of Base of Cone = π × r2 Surface Area of Side of Cone = π × r × s Surface Area of Side of Cone = π × r × √(r2 +h2) Volume of Cone = π × r2 × (h/3) Sphere: It is perfectly symmetrical. It has no edges or vertices (corners). It is not a polyhedron. All points on the surface are the same distance from the centre. Surface Area of Sphere = 4 × π × r2 Volume of Sphere = (4/3) × π × r3 Torus: It can be made by revolving a small circle along a line made by another circle. It has no edges or vertices. It is not a polyhedron. Surface Area of Torus = 4 × π2 × R × r Volume of Torus = 2 × π2 × R × r2
TRIGONOMETRY Trigonometry: Trigonometry is a branch of mathematics that studies triangles and the relationships between their sides and the angles between sides. The Pythagorean Theorem: Pythagorean Theorem states that in any right triangle, the square of the length of the hypotenuse equals the sum of the squares of the lengths of the two other sides. If the hypotenuse has length c, and the legs have lengths a and b, then the theorem states that By the Pythagorean Theorem, the length of the hypotenuse is the length of a leg time’s √2. In a right triangle with acute angles measuring 30 and 60 degrees, the hypotenuse is twice the length of the shorter side, and the longer side is equal to the length of the shorter side time’s √3: These ratios are given by the following trigonometric functions of the known angle A, where a, b and c refer to the lengths of the sides in the accompanying figure. In this right triangle: Sin A = a/c; Cos A = b/c; Tan A = a/b.
Sine: The sine of an angle is the ratio of the length of the opposite side to the length of the hypotenuse.
Cosine: The cosine of an angle is the ratio of the length of the adjacent side to the length of the hypotenuse.
Tangent: The tangent of an angle is the ratio of the length of the perpendicular height (Opposite Side) to the length of the adjacent side (Base).
Cosecant: The cosecant of an angle is the reciprocal of Sin (A), i.e. the ratio of the length of the hypotenuse to the length of the opposite side (perpendicular height):
Secant: The secant of an angle is the reciprocal of Cos (A), i.e. the ratio of the length of the hypotenuse to the length of the adjacent side (base):
Cotangent: The cotangent of an angle is the reciprocal of Tan (A), i.e. the ratio of the length of the adjacent side (base) to the length of the opposite side (perpendicular height):
Right Angle Triangle Equations: In a right angle triangle where hypotenuse length is c and the length of other two sides are a and b, then, The hypotenuse is the side opposite to the 90 degree angle in a right triangle; it is the longest side of the triangle, and one of the two sides adjacent to angle A. The adjacent leg is the other side that is adjacent to angle A. The opposite side is the side that is opposite to angle A. The terms perpendicular and base are sometimes used for the opposite and adjacent sides respectively. The reciprocals of these functions are named the Cosecant (Cosec), Secant (Sec), and Cotangent (Cot), respectively. The inverse functions are called the arcsine, arccosine, and arctangent, respectively. There are arithmetic relations between these functions, which are known as trigonometric identities. The cosine, cotangent, and cosecant are so named because they are respectively the sine, tangent, and secant of the complementary angle abbreviated to "co-". Calculating trigonometric functions: Trigonometric functions are among the earliest uses for mathematical tables. Such tables are incorporated into mathematics textbooks Applications of trigonometry: Sextants are used to measure the angle of the sun or stars with respect to the horizon. Using trigonometry and a marine chronometer, the position of the ship can be determined from such measurements. There are an enormous number of uses of trigonometry and trigonometric functions. For instance, the technique of triangulation is used in astronomy to measure the distance to nearby stars, in geography to measure distances between landmarks, and in satellite navigation systems. The sine and cosine functions are fundamental to the theory of periodic functions such as those that describe sound and light waves. Angle transformation formulae:
Law of sines: The law of sines (also known as the "sine rule") for an arbitrary triangle states: Where R is the radius of the circumscribed circle of the triangle:
Another law involving sines can be used to calculate the area of a triangle. Given two sides and the angle between the sides, the Area of the triangle is: Law of cosines: The law of cosines (known as the cosine formula, or the "cos rule") is an extension of the Pythagorean Theorem to arbitrary triangles: or
Law of tangents: The law of tangents:
Standard identities: Triangle with sides a, b, c and respectively opposite angles A, B, C. Certain equations involving trigonometric functions are true for all angles and are known as trigonometric identities. Identities are those equations that hold true for any value.
Trigonometric Functions: The trigonometric functions are summarized in the following table. The angle θ is the angle between the hypotenuse and the adjacent line – the angle at A in the accompanying diagram. Function
Identities (using radians)
Sin Cos Tan Cot Sec Cosec
For any angle θ and any integer k:
Special values in trigonometric functions: There are some commonly used special values in trigonometric functions, as shown in the following table. Function Sin
0
Cos
1
Tan
0
Cot Sec
1
Cosec
2
Function Sin
1
Cos
0
Tan
1
Cot
1
Sec Cosec
0 2 1
Law of sines: The law of Sine states that for an a triangle with sides a, b, and c and angles opposite those sides A, B and C and R is the triangle's circum radius: then,
Law of cosines: The law of Cosine in the same triangle is an extension of the Pythagorean Theorem:
Law of tangents: The law of Tangent in the same triangle are as follow:
Trigonometrically Ratio: If two triangles are h1 h2 h3 similar, then the ratio of = =; any two sides of a b1 b2 h3 triangle is equal to the ratio of corresponding sides of the other triangle. So Sin A x Cosec A = Cos A x Sec A = Tan A x Cot A = 1 1 + Tan2 A = Sec2 A 1 + Cot2 A = Cosec2 A Tan A Tan A - Tan B + Tan B Tan (A -B) = Tan (A + B) = 1 + Tan A x Tan B 1 – Tan A x Tan B Trigonometric Law of Cosines: In a triangle ABC, the resultant is calculated by applying the following law of cosines to the triangle ABC, R2 = P2 + Q2 – 2 P Q cos A Where, A is the angle between the two forces represented by two sides of the triangle. 2 Tan A Sin 2A = 2 Sin A x Cos A = 1 + Tan2A 1 - Tan2A Cos 2A = 1- 2 Sin2A = 1 + Tan2A Cos 2A = Cos2 A - Sin2 A = 2 Cos2 A –1 2 Tan A Tan 2A = 1 - Tan2A
TRIGONOMETRIC THEOREMS: The measures of the interior angles of the triangle always add up to 180 degrees. An exterior angle of a triangle is an angle that is a linear pair (supplementary) to an interior angle. The measure of an exterior angle of a triangle is
equal to the sum of the measures of the two interior angles that are not adjacent to it; this is the exterior angle theorem. The sum of the measures of the three exterior angles of any triangle is 360 degrees. The sum of the lengths of any two sides of a triangle always exceeds the length of the third side, a principle known as the triangle inequality. Two triangles are said to be similar if every angle of one triangle has the same measure as the corresponding angle in the other triangle. The corresponding sides of similar triangles have lengths that are in the same proportion, and this property is also sufficient to establish similarity. If two corresponding internal angles of two triangles have the same measure, the triangles are similar. If two corresponding sides of two triangles are in proportion, and their included angles have the same measure, then the triangles are similar. If three corresponding sides of two triangles are in proportion, then the triangles are similar. Two triangles that are congruent have exactly the same size and shape and all pairs of corresponding interior angles are equal in measure, and all pairs of corresponding sides have the same length. When two sides of a triangle have the same length as two sides in the other triangle and the included angles have the same measure (SAS Postulate), then these two triangles are congruent. When two interior angles and the included side in a triangle have the same measure and length, respectively, as those in the other triangle (ASA), then these two triangles are congruent. When each side of a triangle has the same length as a corresponding side of the other triangle (SSS), then these two triangles are congruent. When two angles and a corresponding (nonincluded) side in a triangle have the same measure and length, respectively, as those in the other triangle (AAS), then these two triangles are congruent. When the hypotenuse and a leg in a right triangle have the same length as those in another right triangle (RHS), then these two triangles are congruent. When the hypotenuse and an acute angle in one right triangle have the same length and measure as those in the
other right triangle (AAS), these two triangles are congruent.
C ALCULUS Calculus: In the case of a particle travelling in a straight line, its position, x, is given by x (t) where t is time and x(t) means that x is a function of t. The derivative of this function is equal to the infinitesimal change in quantity, dx, per infinitesimal change in time, dt. This change in displacement per change in time is the velocity v of the particle. By Equation it is given as: or
Theorem of Calculus: There are two parts to the Fundamental Theorem of Calculus, the first part deals with the derivative of an anti-derivative, while the second part deals with the relationship between anti-derivatives and definite integrals. First part: Let, ƒ be a continuous real-valued function defined on a closed interval [a, b]. Let, F be the function defined, for all x in [a, b], by, Then, F is continuous on [a, b], differentiable on the open interval (a, b), and for all x in (a, b). Second part: Let ƒ be a real-valued function defined on a closed interval [a, b] that admits an antiderivative g on [a, b]. That is, ƒ and g are functions such that for all x in [a, b], If ƒ is integral on [a, b] then
Logarithm: The logarithm of a number ‘y’ with respect to base ‘b’ is the exponent to which ‘b’ has to be raised in order to yield ‘y’. In other words, the logarithm of ‘y’ to base ‘b’ is the solution ‘x’ of the equation: The logarithm is denoted log b y (pronounced as "the logarithm of y to base b", or "base-b logarithm of y"). In logarithm, the base b must be a positive real number not equal to 1 and y must be a positive number. The graph of the logarithm to base 2 crosses the x-axis (horizontal axis) at 1 and passes through the points with coordinates (2, 1), (4, 2), and (8, 3). The logarithm of a number is the exponent by which a fixed number, the base, has to be raised to produce that number. Example: The logarithm of 1000 to base 10 is 3, because 1000 is 10 to the power 3. 1000 = three times 10 = 103 = 10×10×10. More generally, if x = by, then y is the logarithm of x to base b, and is written logb(x). So, log10 (1000) = 3. The logarithm relies on the fact that the logarithm of a product is the sum of the logarithms of the factors:
The logarithm to base b = 10 is called the common logarithm and has many applications in engineering. The base of the natural logarithm is the constant e (e = 2.718). It is widespread in pure mathematics, and especially in calculus. The binary logarithm uses base b = 2 and is prominent in computer science. Example 1: The decibel is a logarithmic unit quantifying sound pressure and voltage ratios. In chemistry, pH is a logarithmic measure for the acidity of an aqueous solution. Logarithms are common place in scientific formulas, Example 2: log2 (16) = 4, since 4 times 2 = 2×2×2×2 = 16. Logarithms can also be negative: Since, Example 3: log10 (150) is approximately 2.176, which lies between 2 and 3, just as 150 lies between 102 = 100 and 103 = 1000. Finally, for any base b, logb (b) = 1 and logb (1) = 0, since b1 = b and b0 = 1, respectively. Particular bases: Among all choices for the base b, three are particularly common. These are b = 10, b = e (the irrational mathematical constant = 2.71828), and b = 2. In mathematical analysis, the logarithm to base e is widespread because of its particular analytical properties. On the other hand, base-10 logarithms are easy to use for manual calculations in the decimal number system:
1.7
Abbreviations
< Less Than AC Air Cooled > Greater Than AC Alternating Current = Equal To ACI Alloy Casting Institute ≥ Greater or Equal ADI Austempered Ductile Iron ABS AcrylonitrileISBL Inside Battery Limit butadiene-styrene ISCC Inter granular StressABS American Bureau Corrosion Cracking of Shipping It Steam Tracing Insulation Ac 1 Temperature at IT Isothermal which austenite Transformation Ac 3 Temperature at ITP Inspection Test Plan which transformation of ferrite IW Induction Welding to austenite is completed on J Joule heating JIS Japanese Industrial Standard Ac cm Temperature at K Kelvin which cementite completes KG Kilogram solution in austenite KG/CM2 Kilogram/ Square Centimetre Ae cm, Ae 1, Ae 3 Km Kilometre Equilibrium Transformation SWG Stubs’ Wire Gauge/Swage Nipple Temperatures in steels T&G Tongue & Groove AI Instrument Air T&C Threaded & Coupled AK Aluminium Killed T/T Tangent to Material Tangent Al Aluminium AMS Aerospace Material Specification AP Plant Air LM Large Male Ar 1 Temperature at which transformation to LNG Liquefied Natural Gas Ferrite or cementite is completed on cooling LO Locked Open Ar 3 Temperature at which transformation of LR Large Radius austenite to ferrite begins on cooling LRL Location Reference Line AS Alloy Steel LT Large Tongue ATM Atmosphere LT Level Transmitter AWG American Wire Gage LTCS Low Temperature Carbon Steel BAS Bell & Spigot LW Lap Weld BBE Bevel Both Ends LWN Long Welding Neck BCC Body-Centred Cubic M&F Male & Female BCT Body-Centred Tetragonal MAINT Maintenance BD Blow Down MAX Maximum BDD Dry Blow Down MC Mill Certificate BDW Wet Blow Down Mg Mega gram BE Bevel End MH Man Hole
BF Blind Flange BHN Brinell hardness number BID Brinell Indentation Diameter BIS Bureau of Indian Standard BL Battery Limit BLDG Buildings BLE Bevel Large Ends BLN Blind BOM Bill of Material BOP Bottom of Pipe BOT.F Bottom Flat BS British Standards BSE Bevel Small Ends BTL Bottom Tangent Line BTU British thermal unit Butyl Butyl rubber GR-1 (IIR) BV Bureau Verities BW Butt Weld BWG Birmingham Wire Gage C to F Centre to Face CA Corrosion Allowance CAF Compressed Asbestos Fibres CAT Catalyst CAT`D`Category-D service CC Combined Carbon CDA Copper Development Association CE Carbon Equivalent CF Chemical Feed CFM Cubic Feet per Minute CG Centre of Gravity CGA Compressed Gas Association CH Condensate High pressure CH. OP. Chain Operated CI Cast Iron/Corrosion Inspection CL Condensate Low pressure CLR Crack Length Ratio CM Condensate Medium pressure COL Column CONC. Concentric CONN Connection CONT Continued/Continuation CP Cathodes Protection
MI Malleable Iron MIN Minimum MIV Material Issue Voucher MK Mark MNF Manufacturers MOLY Molybdenum Mpa Mega Pascal MPH Mile per Hour MPT Magnetic Particle Test MR Material Requisition MRR Material Receiving Report MS Mild Steel/Material Specification MS Millisecond MSS Manufacturers Standard Society MTO Material Take Off MTR Mitre MW Man Way MWG Mu Gage MWP Maximum Working Pressure N Nitrogen NA Caustic Soda NDE Normally De-energized NDT Non Destructive Testing Ni Nickel NIBR Non Indian Boiler Regulation NIL Normal Interface Level NIP Nipple Nitrile Butadiene-acrylonitrile NLL Normal Liquid Level NOM Nominal NOM.DIA. Nominal Diameter NPS Nominal Pipe Size NPSH Net Positive Suction Head NPSHa Available Net Positive Suctio NPT National Pipe Thread N-Rubber Natural rubber OD Outside Diameter OFC Oxyfuel Gas cutting OFW Oxyfuel Gas Welding OS&Y Oscillate, Swing and yoke OSBL Out Sid Limit
CPLG Coupling CPVC Chlorinated polyvinyl chloride CQ Commercial Quality Cr Chromium CRYO Cryogenic Service CS Carbon Steel CSA Canadian Standards Association CSC Car Sealed Closed CSO Car Sealed Open CSR Crack Sensitivity Ratio C-to-C Centre to Centre CTR Centre CVH Condensate Very High pressure CVN Charpy V-notch d diameter D Drain/Diameter D&T Drill & Tap dB Decibel DC Direct Current DCN Design Change Notice DEG. CENT. Degree Centigrade DEG. Degree DEGN. Design DET. Detail DF Drain Funnel DIA Diameter DIMN Dimension DIN Deutsche Industrie Norman DIS Ductile Iron Society DISCH Discharge DIVN Division DNV Dat Norse Verities DO Dry-Out DP Differential Pressure/Duel Phase DpT Differential Pressure Transmitter DPT Dye Penetration Test DC Drain Connection DI Ductile Iron DWG Drawing E Young’s Modulus E.Fs.W Electric Fusion Welding
OVHD Overhead OWS Oil Water Sewer OZ Ounce P&ID Piping and Instrument Diagram Pa Pascal PAW Plasma Arc Welding PE Plain End PFA Perfluoroalkoxyalkane copolyme PFI Pipe Fabrication Institute PG Pressure Gauge PI Pressure Indicator PLGD Plugged PLNG Planning PLTF Platform PMS Piping Material Specification PO Order POE Plain One End PP Polypropylene Ppb Parts per Billion PPI Plastic Pipe Institute PPM Parts Per Million PQR Procedure Qualification Report PRESS Pressure PS Support PSE Plain Small End PSI Pounds per Square Inch PSIG Ponds per Square Inch Gauge PSV Pressure Safety Valve PT Pressure Transmitter PTFE Teflon/Poly tetra fluoro ethylen PVA Polyvinyl Alcohol PVC Polly Venial Chemical PVDC Polyvinylidene chloride PVDF Poly vinyl difluoride PVP Poly vinyl pyrolidone PWHT Post-Weld Heat Treatment QA Quality Assurance QWB Quench Water Blow down R/L Random Length RAD/R Radius/Radian RECD Received REF Reference
EAF EBW ECC EGW EL ELB ELC EOL EPDM EPT Eq ERW ESW EW EXH FAB FCAW Welding FCC FCO FDN FEP FF FG FH FI Fig FKM FL FLD FLG FLGD FLI Flare FLR FLW Flare FN FO FQI FRP FRW FS FSD
Electric Arc Furnace Electron Beam Welding Eccentric Electro Gas Welding Elevation Elbow Extra-Low Carbon Elbolet Ethylene-propylene-diene Ethylene-propylene terpolymer Equation Electric Resistance Welding Electro Slag Welding Eye Wash Exhaust Fabricated Flux-Cored Arc Face-Centred Cubic Field Change Order Foundation Fluorethylenepropylene Flat Face Fuel Gas /Flow Glass Fire Hydrant Flow Indicator Figure Fluoroelastomer Flare Dry Flare Flange Flanged Intermediate Floor/Flare Wet Ferrite Number Fuel Oil Flow Quantity Indicator Fibre Reinforced Polyethylene Friction Welding Forged Steel Flat Side Down
REV Revision RF Raised Face RMS Root Mean Squire RPM Revolutions per Minute RSP Resistance Spot Welding RSW Resistance Seam welding RTJ Ring Type Joint S Sample Connection S/D Shut Down SAE Society of Automotive Engineers SAT Saturated SAW Submerged Arc Welding SBR Styrene Butadiene SC Sample Cooler SCC StressCracking SCF Stress Concentration Factor SCH Schedule SCRD Screwed SDL shutdown Level SERR.FIN Serrated Finish SG Sight Glass SGS SGS Inspection Service SH Spring Hanger SH Steam (High Pressure) SHT Sheet SI Systeme International d`Unites SL Steam (Low Pressure) SM Steam (Medium Pressure) SMAW Shielded Metal-Arc Welding SMLS Seamless SMTS Specified Minimum Tensile Strength SMYS Specified Minimum Yield Strength SO Steam Out/Slip - On SOL Sockolet SP Special SP. GR. Gravity SPCR Spacer SPEC Specification SPWD Spiral Wound SR Short Radius
FSU Ft FTG F-to-F FZ G Gal GALV Gm GMAW GN Gpa GPM GR Gr GTAW HAZ HB HC HCL HD HDPE HDR HEX HH HIC HIL HK HLL HOD HOR HP HPP HR HS HSE HSLA HSS HTLA HV HVY Hz Ia
Flat Side Up Foot Fitting Face To Face Fusion Zone Modulus of rigidity Gallon Galvanized Gram Gas Metal Arc Welding General Notes Giga Pascal Gallons per minute Grade Graphite Gas Tungsten Arc Welding Heat Affected Zone Brinell hardness Hose Connection Hydrochloric Acid Hold Down High-density polyethylene Header Hexagon handhold Hydrogen Induced Cracking High Interface Level Knoop Hardness High Liquid Level Head of Department Horizontal High Pressure/Horse Power High Point Plinth Rockwell hardness Hose Station Health Safety & Environment High-Strength Low Alloy High Speed Steel Heat-Treatable Low Alloy Vickers hardness Heavy Hertz Noise Attenuation Insulation
SS Stainless Steel SSC Sulphide Stress Cracking ST Steal ST Steam Trap STA Steam Trap Assembly STAW Spray Transfer Arc Welding STD Standard STM Steam STN Station STR Strainer SV Safety Vent/Steam Vent SW Socket Weld TBE Threaded Both Ends TC Total Carbon TE Threaded End TEMP Temperature TEMP STR Temporary Strainer THDD/THRD Threaded THK Thickness THRU Through TI Temperature Indicator TIG Tungsten Inert Gas (Welding) TIR Total Reading TL Tangent Line TLE Threaded Large End TOE Threaded One End TOL Threadolet TOS Top of Sleeper /Top Of Steel TSE Threaded Small End TSO Tight Shut-Off TYP Typical UNI Ente Nazionale Italiano di Unificazione UNS Unified Numbering System UT Ultrasonic Testing UTS Ultimate Tensile Strength V Vent/Vapour/Volt VAC Vacuum VC Connection VERT Vertical VF Vendor Furnished VHN Vickers Hardness Number
IBR Indian Boiler Regulations Ic Cold Insulation ID Inside Diameter INCH DIA. Inch Diameter Ie Electric Tracing Insulation IFI Industrial Fasteners Institute Ih Hot Insulation IIW International Institute of Welding Ij Jacketed Pipe Insulation IM Inch Meter In Inch INS Insulation/Insulated INST Instrument INT Interface INV Invert INV.LEV. Invert Level IOP Integrated Offsite Piping IS Indian Standard Is Insulation for Safety KN Kilo Newton KPa Kilo Pascal KSI Kilo per Square Inch Ksi Kips (1000 lbf) per square inch KV Kilovolt KW Kilowatt Lb Pound Lbf Pound force LC Locked Close LF Large Female LIL Low Interface Level LJ Lap Joint LLL Low liquid Level LLOYDS Lloyds Register of Industrial Service
VOL Volume W Watt WH Ware House WI Work Instruction WLD Weld WN Weld Neck WO Wash Oil WOL Weldolet WP Working Pressure WPS Welding Specification WRC Welding Research Council WT Weight XH Extra Heavy XS Extra Strong XXH Doub Heavy XXS Double Extra Strong YR Year YS Yield Strength Alloying Elements Symbol: Ag Silver Al Aluminium Au Gold B Boron Be Beryllium C Carbon Co Cobalt Cr Chromium Cu Copper Fe Iron Mg Magnesium Mn Manganese Mo Molybdenum Ni Nickel P Phosphorus Pb Lead S Sulphur Si Silicon Sn Tin Ti Titanium U Uranium V Vanadium W Tungsten Zn Zinc
Zr
Zirconium
1.8
Definitions
45 Degree Elbow: The change in direction required is 45°. A 45 degree elbow is also called a "45 bend" or "45 ell". 90 Degree Elbow: The change in direction required is 90°. A 90 degree elbow is also called a "90 bend" or "90 ell". It is a fitting which is bent in such a way to produce 90 degree change in the direction of flow in the pipe. It used to change the direction in piping and is also sometimes called a "quarter bend". Acid Embrittlement: It is a form of hydrogen Embrittlement that may be induced into some metals by acid cleaning treatment. Aging: Aging allows the alloying elements to diffuse through the microstructure and form intermetallic particles, which increases the strength of the alloy. Aluminium Alloys and some Stainless Steel are hardened by aging. Alloy Steel: The steel with added alloying elements with distinctive properties other than carbon is called alloy steel. The alloying elements are added in the molten metal in the cradle in steel melting shop and alloy steel ingot is cast. Alloying Element: Chromium, nickel, vanadium and manganese are alloying elements added in the furnace in steel melting shop to improve the quality of piping material before ingot is cast. These elements are called alloying elements. Alloys: Two or more metals mixed together in molten condition are called alloys. Annealing: Annealing consists of heating ferrous alloys beyond the upper critical temperature and cooling very slowly, resulting in the formation of pearlite. This will produce a refined microstructure and soften a metal for cold working, improve machine ability, or enhance properties like electrical conductivity. The slow cooling is done to allow full precipitation of the constituents to produce a refined and a uniform microstructure. Annealing is used to remove the hardness caused by cold working. Anode: The electrode at which oxidation or corrosion occurs is known as anode Anodic Polarization: It is a reduction from the initial potential resulting from current flow effects at or near the anode surface. Potential becomes more active (negative) because of Anodic polarization. Polarization of anode is the decrease in the initial anode potential resulting from current flow effects at or near the anode surface. Potential becomes more noble (more positive) because of anode polarization. Arc Seam Weld: A seam weld made by an arc welding process is called arc seam weld. Arc Strike: Any inadvertent change in the contour of the finished weld or base material resulting from an arc generated by the passage of electric energy between the surface of the finished weld or base material and a current source is called an arc strike Arc Stud Welding: An arc welding process in which coalescence is produced by heating with an arc drawn between a metal studs or similar part and the other work part, until the surfaces to be joined are properly heated, when they are brought together under pressure. Arc Welding: It is a welding process in which heat for welding is produced to fuse the metals for joining together with an electric arc, with or without using any filler metal. Austenitic Steel: It is a type of stainless steel containing austenite, a solid solution of carbon in iron. The prominent properties of austenitic steels are that it cannot be hardened by heat treatment. It can be
hardened by cold working such as hammering & rolling etc. Automatic Welding: It is a process of welding in which operator uses equipment to carry out the welding operation without any manual control. Back Gouging: It is the removal of the weld metal and base metal from other side of a partially welded joint to ensure complete penetration upon subsequent welding from that side. Back Pressure Valve: It is similar to the safety valve with a constant back pressure so that it relieves any excess back pressure of fluid to atmosphere or elsewhere. It opens or closes automatically relative to the backpressure setting. Backing Ring: A metal strip used on the backside of the root of weld to prevent weld spatters at bottom side of butt-welded joint. It ensures the complete penetration of the welded joint at root. Back-Step Welding: It is a welding technique to minimize the distortion at welding joint. In this technique the joint is welded with a series of short runs in a direction opposite to the general forward direction of welding. Ball Valve: Ball Valve has a spherical disc (ball) with a hole/port in the centre to control the flow through it. When the port of the valve is in line with both ends of pipe, flow will occur. When the hole is perpendicular to the axis of the pipe, the valve is closed and flow is blocked. The handle or lever is in line with the port position indicates the valve's open position. Ball valve’s supporting pressures is up to 1000 bars and temperatures up to 482°F (250°C). Barb: A barb is a fitting and used to connect flexible hoses to pipes. A barb has a male-thread at one end to mate with the female-threaded coupling to connect with pipe. The other end of the Barb has either a single or multiple barbed tubes having a tapered stub with ridges which is inserted into the flexible hose to secure it. An adjustable worm driver screw clamp helps to keep the hose from slipping off the barbed tube. Base Metal: Two metals which are to be welded together or cut is called base metals. It is also called parent metals. Bead: The metal deposited by a single run of welding is called the bead of welding. Bevel Angle: The angle formed between two bevelled edges of the two metals welded together is called bevel angle. Bevel End: Pipe or fitting edge is finished inclined at certain angle to the longitudinal axis of the pipe is called bevel end Bimetallic Corrosion: This is corrosion resulting from dissimilar metal contact; i.e., it is a galvanic corrosion Bleeder: It is a small valve or check valve to discharge off fluid from inside of the piping system. Blind flanges: This is a flange without any opening cut at the centre. It is used to close or to blind the flanged end of the pipe. Blind flanges do not have a bore and is used to shut off a piping system or vassal opening. Its design permits easy access to vassal or piping system for inspection purpose. It can be supplied with or without hubs at the manufacturer's option. Block Welding: It is a technique of welding in which the full joint is welded in sections. A short section of the joint is completely welded to the full depth before proceeding to weld the next section in the like manner. This is continued till the joint is welded completely Bond: This is the junction surface of the base metal and the weld metal or of the paint and any metallic surface. Branch: It is a tapping taken from the main line header in between inlet point and outlet point of the piping system to tap the fluid from that point.
Brazing: Brazing is a thermal joining process of joining two pieces of the base metal with a molten brazing filler metal; which is allowed to be drawn into a capillary gap between them. Brazing filler metals have very high melting points, but always below the melting point of the metals being joined. Successfully brazed joints are as strong as the parent metal pieces being joined and are strong and ductile. Breaking Load: This is the maximum load at which the fracture of the material takes place. In case of small diameter wire or other material, it is very difficult to distinguish between the breaking load and the maximum load applied before rapture, the maximum load is taken as the breaking load of the material. Brinell hardness Test: It is a test for determining the hardness of a material by forcing a hard ball of specified diameter into the metal under a specified load. This hardness test provides some measure of mechanical properties. It the comparative hardness obtained by measuring the diameter of the indent made by a steel ball forced into the test piece under a known load. Brittle Fracture: It is a fracture of a metal with little or no plastic deformation. Brittleness: It is a property of a material, which leads to the propagation of a fracture without appreciable deformation. Butt Weld Joint: It is a weld joint of two metals joined together end to end without any overlap. On the contrary, there is a gap of 1.2 mm, minimum between two edges at the root. Butt weld is either bevelled or square butt weld type. Butt Welded Pipe: Butt Welded pipe is defined as pipe having one longitudinal seam formed by mechanical pressure to make the welded junction, the edge being furnace heated to the welding temperature prior to welding. Butterfly valve: Butterfly Valves stop, regulate, and allow the fluid flow easily and quickly by a 90 degree rotation of the handle. The disc impinges against a resilient liner and provides bubble tightness with very low operating torque. Butterfly valves are limited to low-pressure, lowtemperature (200 psig, 150 0F) water service. The Butterfly valve uses a flat plate to plate to open and close the pipe system and to control the flow of water. Buttering: Deposition of weld layers on faces of the joint prior to groove preparation for welding. It is done to provide a suitable transition weld deposit for the subsequent completion of the joint. Bypass: It is a method of discharging a small quantity of fluid through a small another passage (pipe) around a large valve without operating a large valve for operational requirement of the piping system. Cap: It is a pipe fitting, usually used in liquid or gas pipe to cover the end of a pipe. A cap is used like plug, except that the pipe caps screws or attaches on the male thread of a pipe or a nipple. Carbon Electrode: It is a non-filler material electrode used in arc welding or cutting, consisting of a carbon or graphite rod. Carbon Equivalent: It is a figure arrived by calculating the total content of carbon with the help of following formula, (CE=C + Mn / 6 + (Cr + Mo + V)/5 + (Ni + Cu) / 15). Carbon Pick-up: While welding the carbon content in weld metal is increased due to fusion with parent metal is called carbon pick-up. Due to this, the carbon content in weld is higher. Carbon Steel: A steel having chiefly carbon as a distinctive element to control the properties of the steel as distinguished from the other elements Cathode Polarization: It is a reduction from the initial potential resulting from current flow effects at or near the cathode surface. Potential becomes more active (negative) because of cathode polarization.
Cathode Protection: It is a process of reduction or elimination of corrosion by making the metal a cathode by means of an impressed d-c current or attachment to a sacrificial anode (usually Mg, Al, or Zn) Cathode: The electrode where the reduction (practically no corrosion) occurs is known as Cathode. Caustic Embrittlement: It is a cracking as a result of the combined action of tensile stresses and corrosion in alkaline solution. Cavitations Corrosion: It is a corrosion damage resulting from cavitations and corrosion. Metal corrodes; pressure develops from collapse of cavity and removes corrosion product, exposing bare metal to repeated corrosion. Deterioration of a surface caused by cavitations (sudden formation and collapse of cavities in a liquid) Cavitations: Sudden formation and sudden collapse of vapour bubbles in a liquid, usually resulting from local low pressures, as on the trailing edge of a propeller; this develops momentary high local pressure which can mechanically destroy a portion of a surface on which the bubbles collapse. Cementation Coating: A coating developed on a metal surface by a high temperature diffusion process (e.g., as carbonisation, colorizing or chromizing). Central vacuum system inlet fittings are intentionally designed with a tighter radius of curvature than any other bends in the system. This is done to insure that if any vacuumed debris becomes stuck, it will jam right at the inlet, where it is easiest to discover and to remove. Chalking: It is a development of a loose, chalky, removable powder on or beneath a coating layer. Chamfering: It is a method of pipe end preparation in an angle for groove butt-welding of the members. Check Valve: It is an automatic stop valve provided with a disc or ball, which operates automatically. It allows the fluid to flow in one direction only. It does not allow the fluid to flow in opposite direction by automatic closing the disc of the valve. It is used to prevent the backflow in the pipeline to stop the backpressure on the pumps or compressors. Chemical Composition: Chemical Composition is the details of content of element present in the metal. Certain elements are objected in the piping material and its upper limit of content or presence is specified for better selection of material. Chloride Stress Cracking: Process streams, which contain water with chlorides over approximately 100 PPM under conditions of concentration and temperature high enough, may cause chloride stress cracking under stress condition in susceptible materials, especially when oxygen is present and temperature is over 140 0F. This is called Chloride stress cracking. Choke: It is a device specially intended to restrict the flow rate of fluids. Classification Society: It is an authoritative inspecting body, which is setting a standard for materials and workmanship. Close joint: When two joints are such that their edges are touching each other, are called close joints. Coalescence: It is a process of melting and joining together into one body of the materials being welded. Coated Electrode: The coated electrode is a metal core wire surrounded by a thick coating applied by extrusion, winding, or other process. The success of the welding depends on the composition of the coating, which varies to suit the different conditions and metals. Codes: Codes define a set of general rules or systematic procedures for Design, Fabrication, Installation and Inspection methods, prepared in such a manner that is adopted by legal jurisdiction and make into a law.
Cold Bending: Cold bending is the bending of pipe at atmospheric or around atmospheric temperature below the specified phase-change temperature or transformation temperature of the metal. Combustible Liquids: Combustible Liquids are liquids that have flash points at or above 37.80C. Companion flange: Flange perfectly suited in all respect to connect with another flange or valve flange is called companion flange. Complete fusion: While welding, when both the surfaces of parent metals to be welded together gets melted completely and gets united, it is called complete fusion. Composite Electrode: It is multi component filler metal electrodes in various physical forms, such as stranded wires or tubes. Compressed Fibre Gasket: This is a Non-Metallic Gasket, which has the ability to withstand high compressive loads and seal the flange joint.. Compressive strength: The maximum value of stress in compression, which the material is capable of sustaining without going to plastic phase of materials, is known as compressive strength. Compressive stress: It is a stress, which resists any force tending to press to crush or squeeze the body. It acts normal / perpendicular to the cross sectional plane towards the plane. Connection types: Much of the work of installing a piping or plumbing system involves making leak proof, reliable connections. Depending on the technology used, basic skills may be required or specialized skills and professional licensure may be required. Consumable Insert: The filler metal placed in the root of the weld to be completely fused with parent metals is called the consumable insert. Consumable: IT is an electrode or filler metal used for welding. It melts and gets mixed in parent metals and thus is consumed in welding. Contact Tube: It is a device, which transfers the current to the electrode continuously. Continuous Weld: When the welding of any joint is done continuously without leaving any space in between throughout the length is called continuous weld. Contract: It is an agreement document between the owner and the contractor to execute the work as per specification, code, and terms and conditions. Controlled Cooling: Cooling from a higher temperature to a lower temperature in a predetermined rate of cooling to avoid hardening or cracking of metal and to achieve a desire metallurgical microstructure. This is done with covering the heated metal with insulation. Corner joint: It is a weld joint between two members to be welded together and is located approximately at right angle to each other. Corrosion Fatigue Limit: The maximum cyclic stress value that a metal can withstand for a specified number of cycles or length of time in a given corrosive environment. Corrosion Rate: The speed with which the corrosion progresses is called Corrosion Rate. It is expressed in the unit of “mdd” (Milligrams per square decimetre per day) for weight change or “mpy” (mils per year) or Microns per year for thickness change. Corrosion Resistance: Material of same group, such as carbon steel, alloy steel and stainless steel, varies in respect of their chemicals composition and its ratio and also on their micro / macro structures, manufacturing process, and heat treatment and inspection methods followed during manufacturing. Different materials are used for construction of pipes and tubes. These are Carbon Steel, Iron, Non Ferrous, Plastic, Glass, and Lined metal. Corrosion: Corrosion is a mechanism by means of which metal and oxygen react to reach to the
equilibrium. It is a process of oxidizing of metal in presence of oxygen and moisture because moisture increases the rate of oxidization. Corrosion is the deterioration of a metal or its properties because of a reaction with the environment Corrosion-Erosion: The phenomenon of a protective film of corrosion product being eroded away by the erosive action of the process fluid, exposing fresh metal which then corrodes. The presence of suspended particles greatly accelerates the abrasive action. Corrosive Gas: A gas which is dissolved in water or liquid causes metal attack, usually included is hydrogen sulphide (H2 S), Carbon dioxide (CO2), and Oxygen (O2). Corrosive Hydrocarbon Service: It is a process stream, which contains water or Brine and carbon dioxide (CO2), hydrogen sulphide (H2 S), Oxygen (O2) or other corrosive agents under conditions, which cause metal loss. Corrugated Gaskets: The Corrugated Gaskets are constant seating gaskets, which have two components; a solid carrier ring of stainless steel and sealing elements of some compressible material installed within two opposing channels, one channel on either side of the carrier ring. The sealing elements are typically made from an expanded graphite, expanded poly-tetra-flouro-ethylene (PTFE), vermiculite, suitable to the process fluid and application. The constant seating stress gaskets provide the flange perfect sealing surfaces. Coupling: Coupling is used to connect two pipes either by thread or by weld joint. If the size of the pipe is not the same, the fitting may be called a reducing coupling or reducer, or an adapter. Covered Electrode: It is a filler metal electrode consisting of a core of a bare metal wire covered with flux materials to provide sufficient covering to the weld with inert gas during welding and a slag covering to the weld. Crack: It is a discontinuity in the welded metal or a fracture in weld metal. A sharp tip and high ratio of length and width to displacement characterize it. Cracking: Fracture of a metal in a brittle manner along a single or branched path is called cracking. Crater: The depression left at the end of the final welding surface is called the crater. Creep and Stress-rupture: When a load is applied to a metal at an elevated temperature over a prolonged period of time, the metal may undergo continuous plastic deformation. It may experience a progressive change in its dimensions. The amount of gradual deformation depends on the composition, the process temperature and heat treatment of the material and the shape of the section. Creep at elevated temperatures may terminate in fracture even at load considerably below the shorttime tensile strength. Such high-temperature fractures are commonly referred to as Creep or stressrupture failures. Long-time tests, generally under constant load, carried out to fracture are called stress-to-rupture tests or Creep test. Creep Strength: It is the stress which, when applied to a material at a specific elevated temperature, will cause a specified amount of elongation. Creep strength of a material indicates the rate of deformation of a material at elevated temperatures, under a given load, with respect to time. Creep: It is a phase when all metals flow under stress to a sufficient high temperature i.e. a phase of plastic flow of metals. The higher the temperature and stress, the greater is the tendency to creep i, e to plastic flow of any metal. Creep-test Data: The conventional creep test represents a precise measurement of the deformation of a tensile specimen exposed under a constant load at a particular elevated temperature. The tests are performed with very close temperature control and they are usually conducted for periods of from 1,000 to 10,000 or 20,000 hr. The elongation is read at more or less regular time intervals.
Crevice Corrosion: Localized corrosion resulting from the formation of a concentration cell in a crevice formed between a metal and a non-metal, or between two metal surfaces is called crevice corrosion. Critical Humidity: A humidity level above which corrosion in air increases sharply are called Critical Humidity. Cross: Cross is a fitting used to branch the piping in 4-ways. A cross has one inlet and three outlets, or vice versa. Cross fittings can generate a huge amount of stress on pipe as temperature changes, because they are at the centre of four connection points. Cross is common in fire sprinkler systems, but not in piping. Current Density: It is the current per unit area, generally expressed as amps per square feet or milliamps per square feet, or milliamps per square centimetre. Cutting Torch: It is a device to flow acetylene gas for burning and heating the metal and then oxygen jet at a controlled pressure is discharged to cut the metal. Deactivation: The process of removing active constituents from a corroding medium, e.g., removal of dissolved oxygen from water. De-alloying: The selective corrosion (removal) of a metallic constituent from an alloy, usually in the form of ions is called de-alloying Deep Penetration Electrode: These are electrodes designed especially for a technique for making joint by fusing together a considerable amount of the parent metal with the addition of comparatively little filler metal to provide the deep penetration Defect: Any discontinuity in the weld metal in the form of porosity, slag or crack etc. of the nature not acceptable with reference to standard or specification is called defect. Demineralisation: It is a process of removal of dissolved mineral matter, generally from water. Deposited Metal: It is a process of laying down by fusion of an electrode or filler metal. Any metal in the form of wire is melted and added to the parent metal during welding is called deposited metal. Depth of fusion: The depth of fusion is the height or distance from the surface that fusion extends into the parent metal during welding. Design Conditions: The design conditions are the conditions which include the coincident pressure, temperature, imposed end displacements, thermal expansion of the expansion joint itself and any other possible variations of pressure and temperature, or both, above operating level for cycles during operation. The cycles mean the start-up, shutdown and any abnormal operation. Design Pressure: The pressure in the most severe condition of coincident internal or external pressure at design temperature expected during operation in the pipe is called design pressure. It the maximum allowable working pressure at the design temperature. Design Temperature: The design temperature is the metal temperature of pipe representing in the most severe condition of coincident pressure and temperature expected in normal operation. Diaphragm valve: It is used for isolation as well as throttling. Double Extra Strong: This is a designation to the weight or the thickness of pipe .It is more than the standard thickness of the pipe. Double Welded joint: It is a joint where the welding is done from both sides’ surfaces of the joint. Drain Piping: Drains operate at low pressure and rely on gravity to move fluids. The Drain piping is designed to be as smooth as possible on their interior surfaces. Drain Pipe elbows are usually long radius to reduce flow resistance and solids deposition when the direction of flow is changed. Ductile: It is a property of a metal, which indicate the stretching or bending capacity of the metal.
Ductility: This is the ability of a material to withstand significant plastic deformation prior to fracture. This is measured in term of elongation in the length or reduction in the cross-sectional area of a body during a tensile test of the specimen. It is measured as the percentage of elongation of the fractured test sample over an initial length. Dwell: It is a time during which the electrode rests at any point in each oscillating swing or traverse electrode. Edge Preparation: Edge preparation is a process of gas cutting, filling, grinding or machining of the profile of the end of pipe to make groove for welding. Elastic Deformation: The changes in dimension of a material upon the application of a stress within the elastic range. The material will return to its original dimensions without any permanent deformation after release of the elastic stress. Elastic Limit: The greatest stress to which a material is subjected without retention of any permanent deformation after the stress is removed is called Elastic Limit. In other word, it is the greatest stress that a material can endure without taking up some permanent set is called elastic limit. It is the value of the greatest stress, which a material is capable of sustaining without any permanent change in size or dimension, and retains its original shape & size after release of the complete stress. Elasticity: It is the property of a material, which allows it to recover its original dimensions following deformation by a stress below its elastic limit. In other word, it is the property of a material by virtue of which deformation caused by applied load disappears upon removal of the load. Elbow: An elbow is a pipe fitting installed between two lengths of pipe or tubing to allow a change of direction, usually a 90° or 45° angle or 22.5°. When the two ends differ in size, the fitting is called a reducing elbow or reducer elbow. Electric Current: An electric current is caused by the flow of electrons. However, the electric current flows in a direction opposite to the flow of electrons. (This is the positive current concept.) Electric Resistant Welded (ERW): Electric Resistance Welded pipe is defined as a pipe having one longitudinal seam formed by electric resistance welding, electric flash welding, or electric induction welding without the addition of extraneous metal. Electric Welding: Electric Welding is a process of welding in which an arc is produced for coalescence of metal. The arc is produced with the help of an electrode between the work pieces. Electro Slag Welding: It is a welding process where coalescence of metals is produced with molten slag which melts the filler metals and the surface of the work to be welded. The process is initiated with an arc, which heats the slag. The arc is then extinguished and the conductive slag is maintained in a molten condition by its resistance to electric current passing between the electrode and the work. Electrode Negative: It is a welding process in which the electrode is connected to the negative pole of D.C. supplies during welding. Electrode Positive: It is a welding process where the electrode is connected to positive pole of supply during welding. Electrode: It is a metallic wire covered with flux. It completes welding circuit through which current is passed between the electrode and work piece during welding. The flux coating of the electrode burn and provide an inert gas covering and slag covering to the weld metal. Electrolysis: The chemical changes in an electrolyte caused by an electrical current are called Electrolysis. The use of this term to mean corrosion by stray currents is discouraged. Electron Beam Welding: It is a welding process, which produces coalescence of metals with the heat obtained from a concentrated beam composed primarily of high velocity electrons impinging
upon the surfaces to be welded together. Elongation: The increase in the gauge length of the bar, during tensile test, is called the elongation. It is measured as the percentage of the increase in the length over the original gauge length of the specimen. In the tensile testing, the percent increase in the gage length of a specimen after fracture has occurred is called Elongation. Embrittlement: The severe loss of ductility of a metal is called embrittlement. Endurance Limit: The maximum cyclic stress levels a metal can withstand without a fatigue failure is called the Endurance Limit. Equal Tee: When the size of the branch is same as header pipes, equal tee is used. Erosion: Deterioration of a surface by the abrasive action of moving fluids is called the Erosion. This is accelerated by the presence of solid particles or gas bubbles in suspension. When deterioration is further increased by corrosion, the term Erosion-Corrosion is used. Essential Variable: Essential variables affect the mechanical properties of the weld by change during welding, as described in the specific variables, and are required re-qualification of the WPS. Expansion Bellows: It is a corrugated piping device designed for absorbing expansion and contraction. Expansion Joint: It is piping configuration designed to absorb expansion and contraction. Extra heavy: It is a designation used to designate any pipe, flange, end fitting suitable for a high working pressure. Extra Strong: It is a designation to indicate the thickness or weight per meter of a pipe or fitting. Face: It is the exposed surface on the outside of the piece where either welding or serrated finishing on the surface has been done for seating gasket or closures. Fastener: A fastener is a hardware device that mechanically joins or affixes two or more objects together. Usually the stud bolts are used with full threading and with two heavy hexagonal nuts. The following are the type of fasteners commonly used: Stud bolt with nut; Machine bolt with nut; Fatigue Strength: The maximum stress that can be sustained for a specific number of stresses cycles without failure under fatigue loading is fatigue strength. Corrosive environments have deleterious effects on fatigue life. Fatigue: It is process leading to fracture resulting from repeated stress cycles well below the normal tensile strength. Such failure starts as tiny cracks, which grows to cause total failure. Ferrite Number: It is an arbitrary, standardized value designating the ferrite content of an austenitic stainless steel weld metal. Ferritic: It is pertaining to the body-centred cubic crystal structure (BCC) of many ferrous (Ironbase) metals. Ferrous: It is a material, which contains iron as one of the main constituents. Filler Metal: The metal in the form of wire used for adding or depositing metal to the base metal during welding is called the filler metal. Fillet Weld: It is a weld of triangular cross section for joining two base metals placed on each other like one’s surface to other edge or on surface to surface contact with overlap. Film: It is a thin surface layer that may or may not be visible. Fire Protection Device: Fire protection devices consist of monitoring safety equipments such as flame and smoke detectors, sprinkler systems, fire alarms and enunciators. Fittings: Fittings are used in pipe systems to connect straight pipe or tubing sections, to adapt to different sizes or shapes, and for other purposes, such as regulating or measuring fluid flow. Many
types of fittings are used widely in piping systems. Flame Arrester: Flame Arresters is a safety device that stops fuel combustion by extinguishing the flame. Detonation Flame Arresters prevents propagation of detonations in gas or vapour mixtures in piping system or a pipeline with a significant distance between the ignition sources. Flame detectors: Flame detectors monitor and analyze incoming radiation at selected wavelengths. Flame detectors have optical sensors working at specific spectral ranges to record the incoming radiation at the selected wavelengths. Flammable Gases: Flammable gases are gases that have a flash point blow 37.8 0C. Flammable Liquids: Flammable Liquids are the liquids that have a flash point below 37.80C and a vapour pressure not exceeding 40 pounds per square inch absolute at 37.80C. Flange joint: When the pipes are connected together with the help of flanges welded to each pipe and gaskets in between the flanges with the help of bolts, is called flange joint. Flange: Flanges are generally used to connect two pips length or to pipe and valve, or valve to valve, in-line instrument and/or connection to equipment nozzles. Flange is generally pressing tightly two surfaces to be joined together by means of bolts. A gasket, packing, or an O-ring is always installed between the flanges to prevent leakage Flat Position: It is position of welding in which welding is performed from upper side of the joint and tip of the electrode down below and face of the weld is in horizontal level below the electrode. Fluid: A fluid is a substance, which cannot sustain a shear stress in a combination of the static equilibrium and does not offer any resistance to the distortion of its form. The fluid yields continuously to the tangential forces; even the force is negligible or small in nature. Generally, the gases and the liquids, including vapour, are known as the fluids. Flux, active: It is a flux from which some amount of elements is deposited in the weld metal. Flux, Neutral: It is a flux, which will not cause a significant change in the weld metal composition. Flux: It is a fusible mineral material, which is melted by the welding arc. Flux may be granular or solid coating. Flux stabilizes the welding arc, shield all or the part of the molten weld pool from atmosphere. Flux-Cored Electrode: It is a composite filler metal electrode consisting of a metal tube or other hollow configuration containing ingredients to provide such functions as shielding atmosphere, deoxidisation, and arc stabilization and slag formation. Forehand Welding: It is a welding technique where the welding torch or gun is directed towards the progress of welding. Forged Weld: It is a method of joining two base metals by heating and hammering or pressing against each other to get united together. Frequency: It is the completed number of cycles, which the oscillating current makes in one minute. Friction Welding: It is a solid state welding process, which produces coalescence of materials by the heat obtained from a mechanically induced sliding motion between rubbing surfaces. The work parts are held together under pressure. Fuel Gas: Hydrocarbon gases usually used with oxygen for heating, such as acetylene, natural gas, propane, methyl acetylene etc. are called fuel gas. Full Annealing: It is the heat treatment method where metal is heated to a temperature above transformation range and kept for some time. Then it is cooled in controlled way so that maximum softness of the metal is achieved. Full Fillet Weld: It is a fillet weld whose size is equal to the thickness of the thinner member to be
welded. Furnace Annealing: When the annealing of the product metal is done in the furnace to achieve the maximum required properties of the metal, it is called furnace annealing. Furnace Weld: It is a process of welding to manufacture pipe in which pipe both ends and filler metal are kept in the furnace for melting and fusion together. Fusion Line: In a weld, the interface between weld metal and base metal or between the base metal parts when filler metals are not used is called fusion line. Fusion Zone: The area of the base metals where filler metals and base metals have melted and joined together is called the area of fusion zone. Fusion: The melting of the base metals and filler metal or only base metals to join together are called fusion. Galvanic: It an effect caused by a cell; whenever dissimilar metals come in contact, it results in electrolyte potential. Galvanizing: This is a process in which zinc is deposited on the clean surface of iron or steel to avoid rust. In this process, the surface is cleaned by acid and then rinsing, drying & after pouring the cleaned and dried steel members to a tub of molten zinc. Gas: A gas is a fluid, which tends to expand to fill completely the inside space of the container in which it is kept. Any change in the temperature or pressure of the gas is accompanied by the change in the volume of the gas. Gasket: A gasket is a sealing material made to fit between two flanges of pipe. A gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression. Gasket Type: Various types of gaskets are available depending upon their construction, materials, and features. There are many standards in gasket for flanges of pipes. The gaskets for flanges can be divided in major 4 different categories: Gate valve: Gate Valves have a gate or wedge that moves perpendicular to flow of the service. Stem in the up position, the valve is open and stem in the down position, the valve is closed. The distinct feature of a gate valve is the sealing of passages by the gate / wedge and seats. Globe Valve: Globe Valves are two-port valves openings in the body for fluid flowing in or out vertical to the flow stream in pipe. A Globe Valve is used for regulating flow, which consists of a movable disk-type element and a stationary ring seat in a body. This has an opening that forms a seat onto which a movable disc connected to a stem which is operated by screw action in manual valves. Grain: It is a portion of a solid metal in which the atoms are arranged in an orderly pattern. The irregular junction of two adjacent grains is known as a grain boundary Graphitisation: It is a graphitic Corrosion. Corrosion of grey cast iron in which the metallic constituents are converted to corrosion products, leaving the graphite flakes intact. Graphitisation is also used in a metallurgical sense to mean the decomposition of iron carbide to form iron and graphite. Groove: The gap or profile of the surfaces at the end of two base metals to be welded together is called groove. Groove angle: The total angle included in between the two surfaces of the end of the metals to be welded together is called groove angle. Groove Face: The surface profile at the end of the two metals to be welded together is groove face. Groove weld: It is a type of welding joint in which two base metals are welded together end to end
by chamfering the ends at a certain angle or keeping gap between two ends of base metals. The standard types of groove weld are as follows: Square groove; Single-V groove; Single-bevel groove; Single –U groove; Single-J groove; Single-Flare-Bevel groove; Single-Flare-Vee groove; Double-V groove; Double-bevel groove; Double-U groove; Double-J groove; Double-Fare-bevel groove; and Double-Flare-Vee groove Geysering: It is an effect that occurs in piping handling fluids at or near their boiling temperatures. Under this condition, due to rapid evaluation of vapour within the vertical piping causes rapid expulsion of liquid and a pressure surge is generated that may be destructive to the piping. It may occur in inclined piping also. Hammer weld: While manufacturing pipes of the large diameter 20” and above, the plate is rolled longitudinally and ends are overlapped. The longitudinal overlapped joint is heated to the fusion temperature of the metal and hammered or pressed with power hammer to fuse together to form a pipe. Hard Facing: It is a process of a surfacing variation in which surfacing metal is deposited to reduce the wear of the metal at the surface. Hardness: Hardness is the properties of the metal, which enable them to resist indentation, scratching and abrasion on the surface of the metal. Hardness is the resisting type of the materials property due to which it resists indention, scratching and abrasion. Heat Affected Zone: The portion of the base metals near weld Joints, which are not melted but got, heated up above transformation temperature and thus mechanical properties or microstructures have been changed by welding heat is called heat affected zone. This generally affects corrosion behaviour. Heat Treatment: Heat treatment is a process used to alter the physical and chemical properties of a material. Heat treatment involves the use of heating and cooling, normally to extreme temperatures, to achieve a desired quality of material. Heat treatment techniques include annealing, case hardening, precipitation strengthening, tempering and quenching. Holiday: It is a discontinuity (hole or gap) in a protective coating. Holiday Detector: It is an instrument to detect discontinuity (hole or gap) in a protective coating. Hook’s Law: The Hook’s law governs the relation between stress and strain of a material within its elastic region and states that stress is proportional to strain and independent of time. Horizontal Butt weld: It is a position of welding of pipe or plate in which the pipe axis or plate plane is approximately horizontal or the welding is done on pipe by rotating the pipe. Horizontal Fillet Weld: When the weld joint is approximately in horizontal plane and welding is done in down hand position is called horizontal fillet weld. Hot Bending: The pipe is heated up to the high temperature and bent to predetermined ratios. The pipe is filled with sand before heating to avoid wrinkling and flatness near the bend. Hot Shortness: Hot shortness causes insufficient ductility, which may lead to failure during hot forming. The rupture occur during hot bending of pipe through an angle of approximately less than 22.5 deg. Hot- tensile tests confirms that the steel is hot short and does not possess sufficient or normal ductility at the temperatures at which hot bending or hot forging of steel is generally, done. Hot Working: The plastic deformation of metal at higher temperature so that strains hardening does not occur. Example: The extruding or swaging of pipe around temperature 1200 F to 2000 F. Hydraulic head: Hydraulic head is measured in a column of water using a standpipe piezometer by measuring the height of the water surface in the tube relative to a common datum. The hydraulic head
can be used to determine a hydraulic gradient between two or more points. Hydrogen Blistering: Hydrogen blistering is the presence of atomic hydrogen in specific contaminant (e.g., sulphides, selenides, arsenides, antimony compounds, cyanides.). When the atomic hydrogen enters the metal structures, non-metallic inclusions catalyse the formation of molecular hydrogen within the metal lattice, generating tremendous internal pressures and causing splits, fissures, and even blisters on the metal surface. The tendency to blister can be combated to some extent by using steels of the same grain size and cleanliness as is specified for low-temperature service. Hydrogen Disintegration: It is a deep internal crack in a metal caused by hydrogen. Hydrogen Embrittlement: Martensitic stainless steels have a tendency to pick up hydrogen in its structure and it results hydrogen during the melting process, from the heat-treating atmosphere, or during chemical and electrochemical processes such as pickling and electroplating. Therefore, precautions must be taken with martensitic stainless steels, so that they do not come in contact with hydrogen atmospheres. Hydrogen Embrittlement is less acute in ferritic steels and unknown in austenitic steels. Embrittlement of a metal caused by hydrogen; sometimes observed in catholically protected steel, electroplated parts, pickled steel. Hydrogen Induced Cracking: Hydrogen Induced Cracking occurs in hardened or otherwise highly stressed steels, and is similar in many respects to stress corrosion cracking (SCC). However, cathode protection aggravates the cracking. A large number of hardened steels, martensitic stainless steels, cold-worked austenitic stainless steels, precipitation hardening stainless alloys, etc. are susceptible to hydrogen-induced cracking. Even copper and nickel alloys and cold-worked nickel-chromiummolybdenum alloys at high strength are susceptible, particularly in galvanic couple with a less noble material. Hydrogen piping: Hydrogen piping is a system of pipes used to move hydrogen. Due to issues with hydrogen embrittlement, and corrosion, materials for hydrogen pipes must be carefully selected. Hydrogen has an active electron, and therefore behaves somewhat like a Halogen. The problem is compounded because hydrogen can easily migrate into the crystal structure of most metals. Impact Strength: The amount of energy required fracturing a material under an impact load. The type of specimen, the test conditions, and temperature affects the values and therefore it should be specified in impact test. Incomplete Fusion: While welding, sometimes, the filler and base metals do not melt completely and hence the weld metal does not mix up with parent metal throughout the surface of parent metal completely. The incomplete mixing is called incomplete fusion. Induction Heating: It is a process of heating the pipe joint after welding for heat treatment. The heating is done by placing induction coils around the pipe joint and passing current at high voltage through the coil. Induction Welding: It is a process of welding which produces coalescence of metals through the heat obtained from resistance of the work to induced electric current, with or without the application of pressure. Inhibitor: A substance, which sharply reduces corrosion when, added to water, acid, or other liquid in small amounts. Insulation: It is the process of application of materials of bad conductor of heat on the pipe, equipment or tanks to avoid the heat loss from the fluid contained inside it or to protect the burning of a human. Inter granular corrosion: The corrosion, which occurs preferentially at grain boundaries.
International Standard Atmosphere (ISA): Defined to 101.325 kPa, 15 deg C and 0% humidity. Inter pass Temperature: This is the highest temperature in the weld joint in the section of the previously welded base metals immediately before the next pass of weld is started. Interrupted Welding: Sometimes the welding on carbon steel and chrome-molly alloy steel pipe is required to be done by giving interruption in welding so that the welded area is cooled down to required low temperature to maintain the granular structures of the metal to the requirement. Joint geometry: The shape, size and dimensions of a weld joint in cross section are called joint geometry. Joint Penetration: It is the minimum depth of the groove weld extends from its face into a joint at the root of weld. Joint: It is the junction of the members, which are to be joined or have been joined together. Keyhole: It is a technique of welding in which a concentrated heat source penetrates completely through a work piece, forming a hole at the leading edge of the molten weld metal. . As the heat source progresses, the molten metal fills in behind the hole to form the weld bead. Knife-Line Attack (KLA): It is a form of weld decay sometimes observed on stabilized stainless steel. The zone of attack is very narrow and very close to or in the weld. Lap Joint flange: Lap Joint flange is again similar to a slip flange, but it has radius at the intersection of the bore and the flange face to accommodate a lap stub end. The face on the stub end forms the gasket face of the flange. Its applications are where sections of piping systems need to be dismantled quickly and easily for inspection or replacement. Lap Joint: It is a type of a flange joint where a small flange of the area of the gasket is welded to the pipe being the same material and a carbon steel ring having holes for the bolts is sided over the pipe for bolting connection with another item. Lightly Coated Electrode: It is a filler metal electrode consisting of a metal wire with a light coating applied subsequent to the drawing operation, primarily for stabilizing the arc. Liquid: A liquid is a fluid, which occupies a definite (fixed) volume but the same shape of the container in which it is kept. The liquid has the great resistance to the compression. There is a slight variation in the volume with a considerable pressure applied to the liquid. This is the reason that the liquid is frequently used for hydrostatic testing of the piping. Long Radius (LR) Elbows: The radius is 1.5 times the pipe diameter Low Hydrogen Electrode: Presence of hydrogen in the weld metal is one of the causes of weld cracking. To reduce this tendency, the electrodes are available with coverings designed specially to reduce the amount of diffusible hydrogen. These are known as low hydrogen electrode. Low Pressure Safety Relief Valve: Pressure Safety Relief Valve is a device for relieving excess pressure or vacuum which remains tightly closed up to the set pressure, which is lower than for standard safety relief valves. However, the low pressure safety relief valves fulfil the equivalent quality requirements as standard safety valves. Machine Weld: It is a process of a weld in which the welding is performed with the help of machine under the observation and control of the operator of the machine. Malleable Iron: The cast iron, which is heat-treated in an oven to relieve its brittleness and to improve its tensile strength to enable the material to stretch to an extent without breaking. Manual Welding: It is a process of welding wherein the entire welding operation is performed and controlled by a hand of the welder. Mass: It is the amount of “matter” contained in a given body, and does not vary with the change in its
position on the earth’s surface. The mass of the body is measured by direct comparison with a standard mass by using a lever balance and hence diluting the effect of gravitational force of the earth Melt-in Welding: It is a technique of welding in which the intensity of a concentrated heat source is so adjusted that a weld pass is produced from filler metal added to the leading edge of the molten weld metal by a machine. Metal Dusting: It is a unique form of high-temperature corrosion, which forms a dust-like corrosion product and sometimes develops hemispherical pits on a susceptible metal surface. Metal electrode: It is a filler or no filler electrode, used in arc welding or arc cutting, consisting of a metal wire or rod that has been manufactured by any method and that is either bared or covered with a suitable covering or coating. Mill Length: It is the standard length of pipe manufacture and cut in the mill. The length of the pipe in the mill is maintained to 6.0 meters or sometimes it is 10 to 12 meters. Mill Scale: The heavy oxide layer formed during heat treatment or hot working of metals is called mill scale. It is always referred to steel forming magnetic oxide (magnetite). Modulus of Elasticity: It is a measure of the stiffness or rigidity of a material. It is actually the ratio of stress to corresponding strain in the elastic region of a material, i.e. below the Proportional Limit. It is determined by the tension or compression test. It is also called Young’s Modulus or the Coefficient of the elasticity. This is the value of the stress where the stress-strain relationship is changed to a curve rather than linear on the stress-strain Diagram of the material. Modulus of Elasticity: The ratio of stress to the corresponding strain below the proportional limit is called the modulus of elasticity. Moralizing: It is a process of coating a surface with a layer of metal by spraying, vacuum deposition, dipping, plasma jet or cementation etc. Needle Valve: The needle valves are used for operating the instruments like flow meter, sample point, pressure and temperature gage in line service because it provides very accurate throttling. It is also, preferably, used in high pressure and high temperature line. Net Positive Suction Head: NPSH stands for "Net Positive Suction Head". It is defined as the suction gage reading in feet absolute taken on the suction nozzle corrected to pump centreline, minus the vapour pressure in feet absolute corresponding to the temperature of the liquid, plus velocity head at this point. When boiling liquids are being pumped from a closed vessel NPSH is the static liquid head in the vessel above the pump centreline minus entrance and friction losses. Net Positive Suction Head is the static liquid head in the vessel above the pump centreline minus entrance and friction losses. Nipple: It is a length of pipe less than 12 inch long, forged and both ends are prepared either threading or finished for fillet weld. The diameter of the pipe (nipple) is less than 1.5 inch. Noble Metal: A metal that is not very reactive, e.g., silver, gold or copper and may be found naturally in metallic form on earth. Nominal Pipe Size: Pipe sizes are specified by a number of national and international standards. There are two common methods for designating pipe outside diameter (OD). One is the North American method is called NPS (nominal Pipe Size), which is based on inches and is frequently referred to as NB ("Nominal Bore")). Other is the European version is called DN ("Diameter Nominal" / "Nominal Diameter") and is based on millimetres. For pipe sizes less than NPS 14 inch (DN 350), both methods give a nominal value for the OD, which is not the same as the actual OD. For pipe sizes of NPS 14 inch (DN 350) and greater the NPS size is the actual diameter in inches and the
DN size is equal to NPS times 25 (not 25.4) rounded to a convenient multiple of 50. Nominal Size: The term “nominal size” denotes the approximate inside or outside diameter of pipe in “inch” depending on the size. Nominal Size identifies the size of all pipes, which is seldom equal to the true bore (internal diameter) of the pipe. 350 mm NB and larger pipes have outside diameter equal to nominal pipe size. Nonessential Variables: Nonessential variables are those in which a change may be made during welding or in WPS without re-qualification of WPS and this change does not affect the properties of the weld. Non-Return Valve: It is an automatic stop valve provided with a disc which operates automatically and alloy to flow the fluid only in one direction i.e. in the predetermined direction. It does not alloy the fluid to flow in opposite direction by automatic closing the valve. Normalizing: Normalizing is a process used to provide uniformity in grain size and composition of an alloy. The ferrous alloys are heated above the upper critical temperature and held for 1 hour per inch wall thickness and then is cooled subsequently in still air to room temperature to give harder and stronger steel, but with less ductile for same composition. Normal Temperature and Pressure (NTP): This is defined as 20 0C or 293.15 K or 68 0F temperature and 1 atm or (101.325 kN/m2 or 101.325 kPa or 14.7 psia or 0 psig or 29.92 in Hg or 760 torr) pressure and Density is at 1.204 kg/m3 or (0.075 pounds per cubic foot). Nozzle: It is usually a flange connection of a pipe with the vessel, tank or any equipment. It consists of a short length of pipe welded to the vessel at one end and other end of the pipe is welded to the flange. Olets: Whenever branch connections are required in size where reducing tees are not available and/or when the branch connections are of smaller size as compared to header size, olets are generally used. They are Flanged Olet; Socket-Weld; Threaded Olet; Lateral & Elbow Olets; Nipple Olet and Butt-Weld Olet. O-Ring gaskets: Ring gaskets are also known as RTJ. They are mostly used under extremely high pressure. They are solid rings of metal in different cross sections like oval, round, octagonal. Sometimes they come with hole in centre for pressure equalization. These gaskets are of higher level of metal quality than sheet gaskets and can withstand much higher temperatures and pressures. The key downside is that a solid metal must be greatly compressed in order to become flush with the flange head and prevent leakage. Overhead Position Welding: It is a position of welding of pipe or plate in which welding is performed from the underside of work piece keeping the pipe or plate joint above the welder. Oxidation Resistance: Oxidation resistance of a material at elevated temperature is dependent on the nature of the oxide scale, which forms on the surface of the material. If the scale is loose and porous, the oxidation will continue and the scale becomes thicker until the complete section of metal is oxidized. If on the other hand, the oxide scale is adherent and non-porous, the thin oxide film on the surface will act as a protection to the underlying metal. Carbon steels have a poor oxidation resistance. It can be improved by the addition of chromium, aluminium and silicon. On heating these elements form sense oxide films on the surface of steels and protect the base metal against oxidation. An addition of 5 to 8 percent chromium raises the scale resistance to 700-750 0C, a chromium content of 15-17 percent will prevent scaling up to 950-11000C, and 25 percent chromium will prevent scaling up to 11000C. Oxidation resistance depends upon the composition and chromium content in the steel. It is not much affected by the structure of the steel.
Oxidation: Oxidation is a loss of electrons. When a metal goes from the metallic state to the corroded state (opposite of reduction) there is a loss of electrons. When a metal reacts with oxygen, sulphur, etc., to form a compound as oxide, sulphide, etc., it is oxidized. Oxy-fuel Gas Cutting: It is a metal cutting process used to cut the metals by means of a chemical reaction of oxygen with base metal at elevated temperatures. The necessary temperature is maintained by means of gas flames obtained from the combustion of a specified fuel gas and oxygen. Oxy-fuel Gas Welding: It is a welding process in which coalescence is produced by heating materials with an oxy-fuel gas flame, with or without the use of filler metal. Pass: It is a welding operation nomenclature .A single longitudinal progression of welding operation along the weld length is called a pass. One pass gives one weld bead. Passivation: It is a reduction of the anodic reaction rate of an electrode involves in electrochemical action such as corrosion. Patina: It is a green coating, which is slowly developed on copper and some copper alloys consisting mainly of copper sulphates, carbonates and chlorides after long term exposure to atmosphere. Peaning: It is a process of mechanical working of a metal by means of a hammer blows. Performance Qualification Record: It is a record of all the welding variables used during the welding and the test result of the test carried out on the test coupon for each welding process used during the welding of the test coupon. All these parameters are recorded on a paper. Performance Qualification: It the demonstration of a welder’s or welding operator’s ability to produce welds meeting the prescribed standards or specification. pH Value: It is a measure of the acidity or alkalinity of a solution A value of seven is neutral; low number is acid, large number are alkaline. Pickle (Pickling): It is a process of removal of oxides from the surface of the weld joints or any metals generated during welding or storing of metals. This is a kind of chemical or electrochemical cleaning process. Pipes or metals are pickled in order to remove mill scale, oxide layers or weld discolorations. Pipe: Tubular products are termed as pipe. Nominal Pipe Size identifies pipe with wall thickness defined by schedule number, API designations or weights. Non-standard pipes are specified by nominal size and wall thickness. The principal uses for pipes are Petroleum, Petrochemical and Chemical industries. Piping Components: These are mechanical elements suitable for joining or assembling into a pressure tight fluid containing piping system. Components include pipes, tubes, fittings, flanges, gaskets, bolt-nuts, valves, expansion joints, compensators, hose pipes, traps, strainers, separators, control valves, safety valves, blind flanges, spectacle blinds and drip rings etc. Piping Elements: Any material or work required to plan and install a piping system is called piping elements. Piping elements include design, specifications, materials, components, supports, fabrication, inspection and testing etc. Piping: It is an assembly of piping components, which is used for conveyance of fluids flow with pressure, temperature and hazardous materials in specialized applications. Piping includes piping components and supports but does not include supporting structures, building frame, foundations or equipment. Pitting and Crevice Corrosion: Pitting and crevice corrosion is covered under metallurgical, which may occur in stainless steel piping even though the general corrosion resistance of the material is
excellent. Both result from a highly localized breakdown in the passive film, followed by electrochemical action. The presence of chloride salts, even in minute quantities, can lead to pitting and crevice corrosion of stainless steel, and precaution should be taken in using stainless steel for handling solutions containing chlorides, even though if short-time corrosion tests indicate immunity to this type of attack. Collection or accumulation of solids on surfaces is also conductive to pitting and should be avoided. In general, the molybdenum bearing stainless steels (e.g., types of 316 and 317) are more resistant to pitting and crevice corrosion than the non-molybdenum steels, and their added costs are frequently justified over the latter for this reason. Pitting Factor: It is the Depth of the deepest pit divided by the average penetration as calculated from weight loss. Plain End: This is used to connect or insert into the Socket end of the connecting pipe. This represents the end length of increased diameter into which a pipe end can be fitted. Plasticity: The plasticity of a material is the ability of a material to undergo some degree of deformation permanently without fracture or rupture or failure. Plug Valve: The plug valve also called cock valve, primarily, starts or stops the flow. In service, it takes only quarter turn either to fully open or to completely close the flow, i.e. for quick shut-off. It is, also, not used where regulation or throttling of the flow is required because accurate control is not possible. There is very small pressure drop between the valve ends in this type of valve too. It is used for isolation only. Plug: A plug closes off the end of a pipe. It is similar to a cap but it fits inside the fitting it is mated to. In a threaded iron pipe plumbing system, plugs have male threads. Some of the popular types of plugs are: Mechanical pipe plug; Pneumatic disk pipe plug; Single size pneumatic all rubber pipe plug; Multi-size pneumatic pipe plug; Multi-size flow-through pipe plug and High pressure pipe plug. Plumbing: The plumbing is generally used to describe conveyance of water, gas, or liquid waste in ordinary domestic or commercial environments. Poisson’s Ratio: The Poisson’s Ratio is an important elastic constant, which expresses the relationship existing between lateral strain and axial strain. The value of Poisson’s Ratio varies with different materials. Polarity: The direction of flow of welding during welding with respect to the electrode and the work piece is called polarity. It is of two kinds such as “Positive Polarity” and “Negative Polarity” Polarization: The shift in electrode potential resulting from the effects of current flow, measure with respect to the zero-flow (reversible) potential; i.e., the counter-emf Caused by the products formed or concentration changes in the electrolyte. Porosity: It is a kind of defect in the weld or casting. The presence of gas pockets voids in the weld or casting is called porosity. Positive Polarity: It is the arrangement of direct current arc welding in which the work piece is connected to the negative pole and the electrode is the positive pole of the welding arc. It is also called “Reverse Polarity”. Post Heating: It is the application of heat to a fabricated product, weld or weld subsequent to the fabrication, welding or cutting operation to reduce the hardness of the metal or to stress relieve. The post heating is done either by induction heating coil or in a furnace. Post Weld Heat Treatment: It is a standard procedure of heating of the weld or the fabricated product by the use of induction coil or in a furnace to avert or stress relieve to reduce the hardness the detrimental effects of high temperature and severe temperature gradients inherent in welding of the
weld or the fabricated products. The heating is done to the required temperature and the temperature is maintained minimum for two hours. Then it is cooled under the controlled rate of cooling up to the atmospheric temperature. Preheat temperature: It is the minimum temperature of heating of the weld joint prepared immediately prior to the welding of the joint. In case of multiple passes welding, it is the minimum temperature of heating in the section of the previously deposited weld metal, immediately prior to the welding of subsequent welding. Preheating: It is the application of heat to a weld joint or the work pieces to be welded just before the welding. It is used to minimize the detrimental effect of high temperature and severe thermal gradients inherent in welding. Pressure and Vacuum Relief Valves: These are special devices that function as an end-of-line valve to protect against pressure and vacuum. The valves are connected to a vent header to process vapours. Pressure/Vacuum relief valves are used as inbreathing and out breathing valves and for venting tanks and equipment when an unallowable vacuum or pressure is exceeded. These devices are direct acting weight or spring loaded in-line valves, pallet type and is used to protect plant equipment (tanks, vessels, process piping). Pressure: The pressure is defined as a force per unit area. The value of the atmospheric pressure is taken as 1.033 kg/cm2 or 1.01 bars absolute at sea level. All the pressure gauges read the difference between the actual pressure in any system and the atmospheric pressure. There are two measures of the pressure, such as; Gauge Pressure: The reading of the pressure gauge is known as “Gauge Pressure”. Absolute Pressure: The actual pressure is known as the “Absolute Pressure”. Absolute Pressure = Gauge Pressure + Atmospheric Pressure. Pressure and Temperature Ratings: Temperature and Pressure are the two important factors determining the safe and effective working of any industrial pipe fitting. The range of temperature and pressure depends on the final application, the material being used etc. There are various standards that are laid down in reference to the temperature and pressure parameters. These are as follows: Pressure Relief Valve: The pressure relief valve or pressure safety valve is used in the operating line system to prevent the line over pressurized by releasing the pressure of the line through pop-up of spring loaded valve-seat or ball. Thus, it protects the piping system or the connected equipments from failure. Prime Coat: The first coat of paint applied to inhibit corrosion or improve adherence of the next coat is called prime coat. Proof Strength: This is the tensile stress at which there is a plastic deformation or a permanent set or an elongation of 0.0005” in overall dimension of the body while testing the material in testing machine. It is considered for design of the bolts. The load required producing a permanent setting in the material or an elongation of 0.0005” in overall length, under axial stress in a tensile testing machine, is called the proof strength. Proportional Limit: The maximum stress at which the material or body is capable of sustaining the force without deformation from its original shape is called the proportional limit. It is also said that a material maintains a perfectly uniform rate of strain to stress within the Proportional Limit. Purging: The displacement of any fluid or air from inside of the pipe or underneath and around the welding joint of the pipe by an inert gas, natural gas or any suitable media to clean the inside of pipe or to avoid oxidation or contamination of the pipe or weld material is called purging.
Quenching: Quenching is a process of heating the metal above the upper critical temperature and then cooling very quickly in water, oil or brine at atmospheric Temperature. In ferrous alloys, quenching is most often done to produce a martensite transformation to produce a harder metal, while non-ferrous alloys will usually become softer than normal. Ratings: Ratings are the maximum allowable gage pressures at the corresponding temperature shown in the rating table. Recommended Practice: Good Engineering Practices but which are optional for which procedure documents are prepared by a professional group or committee. Reducer: A reducer allows for a change in pipe size to meet hydraulic flow requirements of the system, or to adapt to existing piping of a different size. Reducers are usually concentric but eccentric reducers are used when required to maintain the same top- or bottom-of-pipe level. Reduction: It is the gain of electrons, when copper is electroplated on steel from a copper sulphate solution (opposite of oxidation). Reinforcement of Weld: It is the weld metal on the face or root of the groove weld in excess of the metal surface. This is done for the specified weld size and to provide extra strength at the weld joint. Relative Humidity: The ratio of the amount of moisture in the air compared to what it could hold if saturated at the temperature involved. Relief Valve: (Pressure Safety Valve): It is a spring loaded valve arranged and set to provide an automatic release or blow off the excess pressure in the piping system. This is a device to safe guard the piping system from unwanted excess pressure damage. Residual Stress: Stress present in the material, which is free from external forces, is called residual stress. These stresses may be due to some prior mechanical deformation, phase transformation, or to no uniform cooling. Resilience: Resilience is the ability of material to resist the wear and tear due to continuous rubbing of the material with other materials. It plays very important role in resisting erosion, abrasion and scratching of the material’s surfaces. Resilience is the capacity of a material to absorb energy elastically and the energy stored is given off exactly as in a spring when the load is removed. Resistance Spot Welding: It is a kind of resistance welding which produce coalescence at the facing surface in one spot by the heat obtained from the resistance to the electric current through the work parts held together under pressure by electrodes. Primarily the size and contour of the electrodes limit the size and shape of the individually formed welds. Resistance Stud Welding: It is a resistance welding process wherein coalescence is produced by the heat obtained from resistance to electric current at the interface between the stud and the work piece, until the surfaces to be joined are properly heated, when they are brought together under pressure. Resistance Welding: It is a kind of welding process in which coalescence is produced by the heat obtained from resistance of the work to the flow of electric current in a circuit of which the work is a part, and by the application of pressure. Retainers: The metallic or non-metallic, consumable or no consumable material (Excluding gas), which is used to contain or shape the molten weld metal, is called retainer. Reverse Polarity: It is an arrangement of direct current arc welding where the work piece is connected to negative pole and the electrode to the positive pole. Reynolds Number: The Reynolds number is a dimensionless group used in fluid mechanics calculations. It is expressed as the product of density, velocity and diameter divided by the viscosity of the fluid.
Ring Joint Gaskets: Ring Joint Gaskets are used with Ring Type Joint (RTJ) flanges. A very high surface stress is developed between an RTJ gasket and the flange groove when RTJ is bolted up in a flange. This leads to plastic deformation of this gasket. Thus, the hardness of the gasket is kept less than the hardness of the groove to achieve coining i.e. bringing two metal surfaces of different hardness so tightly together that the softer surface deforms to match harder surface exactly in shape and finish. Rockwell Hardness Test: It is a common test for determining the hardness of a material based on the depth of penetration of a shaped indenture under a specified load. Root Edge: It is a root face in which the width of face is zero. Root Face: The vertical height of the portion of groove weld face at the root of the joint is called root face. Root Opening: The minimum gap of separation at the bottom of the weld joint of two base metals is called root opening. Root Penetration: The depth by which a weld metal extends into the base metals at the root of a joint as measured at the centre line of root cross section is called root penetration. Root: The bottom portion of the groove weld joint where the two base metals are very near to each other and where the first pass of welding of the joint is done is called root. Run: It the portion of the welding done continuously throughout the length of the work pieces in a single pass. Rusting: It is the corrosion of iron or iron-base alloy to form a reddish brown product of hydrated ferric oxide. Sacrificial Protection: It is a process of reduction or protection of corrosion of a metal in an electrolyte by galvanic ally coupling it to a more anodic metal. Scaling: It is high-temperature corrosion resulting in formation of thick corrosion product layers or deposition of in soluble materials on metal surface, usually inside water boilers or heat exchanger tube. Schedule Number: The schedule number indicates approximate value of the expression 1000 x P/S where P is the service pressure and S is the allowable stress, both expressed in pounds per square inch. Seal weld: It is a thin weld on the threaded joints or between stitches welded joints of structure primarily to obtain leak proof joint or to avoid corrosion of inside surfaces of the members. Seam Weld: It is a continuous weld made between two members in edge to edge contact or upon two overlapping members. Seamless Pipe: Pipe manufactured by piercing and rolling solid billets or by cupping from a plate is called seamless pipe. It is a wrought steel tubular product made without a welded seam. Season Cracking: It is a cracking caused by the combined action of corrosion and internal tensile stresses; it is usually applied to the stress corrosion cracking of brass. Semi Automatic Welding: This is an arc welding process with equipment where the equipment controls only the filler metal feed. The advance of the welding is controlled manually Shear Strength: This is the greatest shear stress at which the material is good enough to sustain the force without plastic deformation of the body. It is calculated by dividing the greatest load applied during the shear or tortional test of the material to rapture it by the original cross sectional area (area before application of the test load) of the body. Shear Stress: It is a stress, which resists any force tending to slide one part of the body across
another layer of the same body. It acts tangentially / parallel to the plane of the body. Shear Stress is the maximum value of stress in shear, which a material is capable to sustain without going to plastic phase of material. Sheet gaskets: Sheet gaskets are simple; they are cut to size either with bolt holes or without holes for standard sizes with various thickness and material suitable to media and temperature pressure of pipeline. This is Non-Metallic Gaskets. Non-Metallic Gaskets are used with flat face or raised face flanges This leads to a very crude, fast and cheap gasket, such as compressed asbestos, a fibrous material such as graphite. Shielded Metal Arc Welding (SMAW): It is an arc welding process in which coalescence is produced by heating with an electric arc between a covered metal electrode and the work piece. The shielding is obtained from decomposition of the electrode covering and filling is obtained from the consumable electrode. Short Radius (SR) Elbows: The radius is 1.0 times the pipe diameter Shot Blasting: It is a mechanical removal of metal oxides and scale from the metal surfaces by the abrasive impingement of small steel pellets. Size of Weld: For groove weld, it is the depth of the Groove joint plus the thickness of penetration at root. For fillet weld, it is the leg length of the largest isosceles right triangle, which can be inscribed within the fillet weld cross section. Skelp: It is a piece of plate prepared by forming and bending and ready for making a butt-welded pipe. Slag Inclusion: It is a weld defect. While welding a non-metallic solid material (slag) are entrapped in the weld metal or between weld metal and parent metal. S.I. Units: The 11th General conference of Weights and Measures has recommended a unified and systematically constituted system of fundamental and derived units for international use. This system of units is now being used in all most all countries including India. In S.I. Units system, the fundamental unit of length, mass and time are Meter, Kilogram and Second respectively. But there is a slight variation in the derived units. India has adopted S.I. Units for all purposes. The international meter, kilogram and second is defined here below: Slip-On flanges: Slip On flanges are slipped over the pipe and then welded from both inside and outside to provide sufficient strength and prevent leakage. This flange is used instead of weld necks by many users because of its lower cost and also the fact that it requires less accuracy when cutting pipe to length. Slushing Compound: Non-drying oil, grease, or wax is known as slushing compound, which is applied on the metal surface to protect from temporary corrosion. Socket Weld Flanges: Socket Weld Flanges are similar to a slip on flanges in outline, but the bore is counter-bored to accept pipe. The diameter of the remaining bore is same as the inside diameter of the pipe. A fillet weld around the hub of the flange attaches the flange to the pipe. An optional interval weld may be applied in high stress applications. Its biggest use is in high pressure system such as hydraulic and steam lines. Socket Weld: It is a fillet weld of two base metals placed on each other with an overlapped position. Soldering: Soldering is a process of connecting two parts together with the help of chemical flux application to the inner sleeve of a joint, and the pipe is inserted and with the use of open flames for heating joints. The joint is then heated using a propane torch or Gas torch, solder is applied to the heated joint, and the melted solder is drawn into the joint by capillary action as the flux vaporizes. A
degree of skill is needed to make soldered joints. Solvent welding: A solvent is applied to PVC, CPVC, ABS, or other plastic piping, to partially dissolve and fuse the adjacent surfaces of piping and fitting. Solvent welding is usually used with a sleeve-type joint, to connect pipe and fittings made of the same (or closely compatible) material. Solvents typically used for plastics are usually toxic, may be carcinogenic, and may also be flammable, requiring adequate ventilation. Spatter Loss: It is the difference in weight between the amount of electrode consumed and amounts of weld deposited. It is a loss of electrode metal during welding due to spatter. Spatter: It is the metal particles expelled and spread over the surface during the arc and gas-welding .IT does not form a part of the weld. Specific Heat: The specific heat of a substance is broadly defined as the amount of heat required to raise the temperature of one unit mass of that substance water through 10 temperatures. Specific gravity: Specific gravity is the ratio of the weight of any volume to the weight of an equal volume of some other substance taken as a standard at stated temperatures. For solids or liquids, the standard is usually water, and for gasses the standard is air or hydrogen. Specification: Few Companies also develop their own Specifications and Guides in order to have consistency in the documentation while executing the job at site by different engineers. These cover various engineering methods, which are considered good practices, with specific recommendations or requirements noted down from the Code and Standards. Codes and Standards, besides being regulations, might also be considered as design aids since they provide guidance from experts. Specimen: It is a sample of the welded piece for a specific test to be carried out on it. The specimen may be a bend test, tension test, impact test, chemical analysis, macro test, hardness test, radiography test etc. Spilling: It is the separation of a surface caused by thermal or mechanical stresses (e.g., cooling, bending etc.) Spiral welded Pipe: It is a pipe manufactured by coiling a plate into a helix and fusion welding of the overlapped or abutted edges. Spiral-Wound Gaskets: Spiral-Wound Gaskets are made with stainless steel outer and inner rings and a centre filled with spirally wound stainless steel tape wound together with graphite and Teflon, formed in V shape. Spiral-Wound Gaskets are used with raised face flanges. Spiral wound gaskets are also used in high pressure pipelines. Internal pressure acts upon the faces of the V, forcing the gasket to seal against the flange faces. These gaskets have proven to be reliable in most applications, and allow lower clamping forces than solid gaskets, albeit with a higher cost. Spot Weld: It is a weld made between or upon overlapping members in which coalescence is produced on spots of the facing surfaces. The weld cross section is approximately circular. Squire Groove Weld: It is a groove weld in which the edges of the pipe or plate is not chamfered but remain as plain end. The squire groove weld is generally done on piping or plate of wall thickness not greater than 3.5 mm. Stabilized Steel: It is a stainless steel, which has been alloys with a carbide- forming element (e.g., Cb, Ti, or Ta) which makes it less or not susceptible to carbide precipitation Stainless Steel: It is alloy steel having unusual corrosion resistance properties due to having elements like Chromium and Nickel in greater percentage. Standard Weight: It is a schedule of weights of pipes to be used by different users Standards: It is a document having standard dimensions of piping components approved by the
competent authority for use by the different users. Standard Documents are prepared by a Professional group or Committee in a proper Engineering Practices that are believed to be good and contain mandatory requirement. Standard Ambient Temperature and Pressure (SATP): This refers to temperature at 25 deg C (298.15 K) and pressure of 101 kPa. Standard Temperature and Pressure (STP): This is commonly used to define standard conditions for temperature and pressure. These are important for the measurements and documentation of chemical and physical processes. Static Head: Static head is the vertical distance between the free level of the source of supply and the point of free discharge, or to the level of the free surface of the discharged liquid. Stress Corrosion Cracking: It is an anodic process, electrochemical in nature. There is a thin film of electrolyte on the metal surface and that both anodic and cathode area exists on the surface covered by the liquid film. A very thin oxide film form almost instantaneously on the surface of all metals exposed to moisture. This oxide-covered surface is much less chemically active than a bare or unveiled surface, and it will be the cathode in an electrolyte. Stress corrosion cracking has been commonly observed under the following conditions: a. When repeated dripping of water takes place on one area of hot stainless steel. b. When migration of water takes place through porous lagging on a steel surface and concentrates salts at that surface. c. A crevice in a heat transfer surface is in ideal hot spot for stress corrosion cracking. Stiffness: The resistance of a material to elastic deformation or deflection is called “Stiffness” or “Rigidity”. Stop Valve: It is a Non-return or check valve. Straight Polarity: It is the arrangement of direct current arc welding leads in which the work is connected to the positive pole and the electrode to the negative pole of the welding arc. Strain: Strain is the behaviour of the material due to which there is a change in size, shape and dimension of the body due to any external force acting on it. Strain is a non-dimensional quantity but its unit of measurement is length per unit of length e.g. centimetre per centimetre. The material subjected to a load may deform, yield or break, depending upon the magnitude of the load, nature of material and its cross-sectional dimension. The resultant deformation expressed as a fractional change in dimension due to all the elementary inter-atomic forces or internal resistances, is called Strain. It is a measured of a change in dimensions of a material when loaded compared to its original size or shape. Linear strain would be the change in length of a part compared to its original length. It is usually expressed as a percentage. Strainers: Strainers are placed in-line with process piping to remove large solid contaminants from the flow. Strainers filter particles and contaminants from fluids. They provide a high degree of resistance to corrosive substances such as acids and solvents and other toxic fluids. Strainers can be cleaned and reused. Strength: The “Strength” of a material is its capacity to withstand destruction under the action of external loads. It is the ability of a material to withstand stress without failure. The strength of a material is defined using the following properties, such as modulus of elasticity; yield strength, and ultimate tensile strength. Stress analysis: Stress analysis is method where process piping and power piping are typically checked by Pipe Stress Engineers to verify that the routing, nozzle loads, hangers, and supports are
properly placed and selected such that allowable pipe stress is not exceeded under different situation such as sustain, operating or hydro test as per the ASME or any other legislative code and local government standards. It is necessary to evaluate the mechanical behaviour of the piping under regular loads (internal pressure and thermal stresses) as well under occasional and intermittent loading cases such as earthquake, high wind or special vibration, and water hammer. This evaluation is usually performed with the assistance of a specialized pipe stress analysis computer program. Stress Corrosion: The corrosion caused by tensile stress is called stress corrosion. Stress Relieving: It is the uniform heating of a fabricated or welded product to a sufficiently high temperature below the critical range, holding, and cooling at the controlled rate of cooling to atmosphere temperature. It is done to relieve the major portion of residual stresses during welding, cold or hot bending, or cutting operation etc. Stress relieving: Stress relieving is done to remove or to reduce the internal stresses created in a metal during cold working, such as welding. The stresses are caused in a number of ways, ranging from cold working to non-uniform cooling. Stress relieving is usually accomplished by heating a metal below the lower critical temperature and then cooling uniformly but slowly. Stress: It is behaviour of the material due to which it tends to resist any external force acting on it. It is the intensity of internal force or component of forces acting at a point in a place in the body. It is expressed in force per unit area of cross section of the body in that place. There are different types of stress e.g. tensile stress, compressive stress, and shear stress and torsion stress. Load or force per unit area of the cross section through which the load is acting is called stress. String Bead: It is a type of weld bead made by moving the electrode in a direction essentially parallel to the axis of the bead. There is no appreciable transverse oscillation of the electrode during welding. Stud Welding: It is a procedure to join two base metals with the help of joining a metal stud to a work piece. Arc, resistance, friction or other suitable method with or without external gas shielding accomplishes the welding. Submerged Arc Welded (SAW) Pipe: Submerged Arc Welded pipe is defined as pipe having one longitudinal seam formed by submerged arc welding. Submerged Arc Welding: It is an arc-welding process in which coalescence is produced by heating with an electric arc between a bare metal electrode and the work piece. A blanket of granular fusible material poured on the work piece shields the welding. Suction head: Suction head (sometimes called head of suction) exists when the pressure measured at the suction nozzle and corrected to the centreline of the pump is above atmospheric pressure. Static suction head is the vertical distance from the free level of the source of supply to centreline of pump. Dynamic suction head is the vertical distance from the source of supply, when pumping at required capacity, to centreline of pump, minus velocity head, entrance, friction, but not minus internal pump losses. Dynamic suction head, as determined on test, is the reading of a gage connected to suction nozzle of pump, minus vertical distance from centre of gage to centre line of pump. Suction head, after deducting the various losses, many be a negative quantity, in which case a condition equivalent to suction lift will prevail. Suction Lift: Suction lift exists when the suction measured at the pump nozzle and corrected to the centreline of the pump is below atmospheric pressure. Static suction lift is the vertical distance from the free level of the source of supply to centreline of pump. Dynamic suction lift is the vertical distance from the source of supply when pumping at required capacity, to centreline of pump, plus
velocity head, entrance and friction loss, but not including internal pump losses, where static suction head exists but where the losses exceed the static suction head the dynamic suction lift is the sum of the velocity head, entrance, friction, minus the static suction head, but not including internal pump losses. Dynamic suction lift as determined on test is the reading of the mercury column connected to suction nozzle of pump, plus vertical distance between point of attachment of mercury column to centreline of pump, plus bead of water resting on mercury column, if any. Sulphide Stress Cracking: It is a Hydrogen-induced cracking of a metal in an environment containing hydrogen sulphide. Process stream containing water and hydrogen sulphide may cause sulphide stress cracking of susceptible materials. This phenomenon is affected by a complex interaction of parameters including metal chemical composition and hardness, heat treatment, microstructure, pH, hydrogen sulphide concentration, stress and temperature. Surfacing: It is a process of depositing layers of material to another surface by welding, brazing or thermal spraying to obtain desired properties or dimensions. Swage Nipples: A short stub of pipe usually threaded steel, brass, chlorinated polyvinyl chloride (CPVC) or copper; occasionally just bare copper. A nipple is defined as being a short stub of pipe which has a male pipe thread at each end, for connecting two other fittings. Nipples are commonly used for plumbing and hoses, and second as valves for funnels and pipes Swaging: It is a method of reducing the end of the pipe with rotating dies, which are pressed intermittently against the pipe end. Tack Weld: It is a small length of weld made to hold two parts of a weld in proper alignment till the final weld is made. Tee: Tee is the most common pipe fittings. It is used to either combine or split a fluid flow. It is a type of pipe fitting which is T-shaped having two outlets, at 90° to the connection to the main line. It is a short piece of pipe with a lateral outlet. Tee Joint: It is the joining two members located approximately at right angles to each other in a form of tee with the help of welding. Temperature: The temperature is defined as the degree of hotness or the level of heat intensity of a body. A hot body is said to be at higher temperature and the cold body is said to be at lower temperature. The thermometer in the scale of “Centigrade or Celsius” and “Fahrenheit” measures the temperature. Tempering: It is a process of heating normalized or quench-hardened steel to a temperature below the transformation temperature (the lower critical temperature, (400 to 1105 ˚F or 205 to 595 ˚C) and cooling at the desired rate up to a specific temperature, which is above the martensite start temperature, and then holding it there until pure bainite can form or internal stresses can be relieved to impart some toughen or the atmospheric temperature. It is also called stress relieving. Tensile strength: The maximum value of stress in tension, which a material is capable to sustain before start of plastic phase of material is known as tensile strength. This is the greatest tensile stress at which the material is good enough to sustain the force without plastic deformation of the body. It is calculated by dividing the greatest load applied during the tensile test of the material to rapture it by the original cross sectional area (area before application of the test load) of the body. Tensile Stress: It is a stress, which resists any force tending to pull a body apart. It acts normal / perpendicular to the cross sectional plane out ward direction. Thus, in the design of piping, it is necessary to know the effects of the three independent variables, such as, stress, time and temperature on the plastic properties and fracture strength of the materials from which the piping to be
constructed. Such information is obtained from creep tests. Test Coupon: It is a piece of sample of plate; pipe or tube either fillet welded or butt-welded material for procedure or performance qualification testing. Test Specimen: It is a sample piece of any material for specific test such as bend test, tension test, impact test, chemical analysis, macro test, or radiography test etc. Thermal Capacity: The thermal capacity of a substance is defined as the amount of heat required to raise the temperature of whole mass of the substance through 10 temperatures. Thermal conductivity: The thermal conductivity is defined as the rate of heat transfer from the higher gradient to the lower gradient in unit area of the surface, one degree of temperature difference and through one unit of thickness in unit time. Threaded Joint: Pipes are threaded at the end and are connected together with the help of coupling is called the threaded joint. Threaded pipe: Steel pipe is often joined using threaded connections, where tapered threads are cut into the end of the tubing segment, sealant is applied in the form of thread sealing compound or thread seal tape (PTFE or Teflon tape), and it is then threaded into a corresponding threaded fitting using a pipe wrench. Throat of Fillet Weld: It is the perpendicular distance from the root of the fillet weld to the hypotenuse of the largest right triangle that can be inscribed within the fillet weld cross section. Toe of Weld: It is the junction between the face of the weld and the base metal. Tortional Stress: It is a kind of shear stress, which resists any force tending to twist the body. It acts along the circular path of the cross section of the body in the plane of cross section. TOTAL DYNAMIC HEAD: Total dynamic head is the vertical distance between source of supply and point of discharge when pumping at required capacity, plus velocity head friction, entrance and exit losses. Total dynamic head as determined on test where suction lift exists, is the reading of the mercury column connected to the suction nozzle of the pump, plus reading of a pressure gage connected to discharge nozzle of pump, plus vertical distance between point of attachment of mercury column and centre of gage, plus excess, if any, of velocity head of discharge over velocity head of suction, as measured at points where the instruments are attached, plus head of water resting on mercury column, if any. Total dynamic head, as determined on tests where suction head exists, is the reading of the gage attached to the discharge nozzle of pump, minus the reading of a gage connected to the suction nozzle of pump, plus or minus vertical distance between centres of gages (depending upon whether suction gage is below or above discharge gage), plus excess, if any, of the velocity head of discharge over velocity head of suction as measured at points where instruments are attached. Total dynamic discharge head is the total dynamic head minus dynamic suction lift, of plus dynamic suction head. Toughness: The ability of a material to absorb energy and deform plastically before fracturing is called Toughness. Toughness is a measure of the amount of energy a material can absorb before actual fracture or failure takes place. The ability of any material to resist the external shock or impact, or to withstand the repeated and reversing nature of stress, or to absorb the energy developed due to overstressing of the material beyond the elastic limit is called toughness of the material. This property of the material is very much desirable in piping because of the nature of piping requirement to absorb the shock due to water hammer and similar form of surge. This is measure by the impact testing of the material I the laboratory. The toughness of a material is dependent upon both strength and ductility. Traps: The traps are used in the steam line to discharge the condensate from the steam in steam piping
without allowing steam to escape from the line. Trepanning: It is the removal of a small portion of weld of pipe or plate welded together for evaluation of weld and base metal soundness. This operation is generally performed with a whole saw. Tube: Tubular products are termed as tube. Tube is specified by outside diameter and wall thickness, expressed in inch or in mm. The principal uses for tube are in heat exchangers, instrument lines, and inter-connections on equipments such as compressors, boilers, and refrigerators. Tubing: The tubing is used for lighter-weight piping, especially types that are flexible enough to be supplied in coiled form. Tungsten electrode: It is a tungsten wire, other than the filler metal and consumable, used in an inert gas arc welding process. Turbnizing: It is a process of mechanically removal of scales from the inside of pipe by means of airdriven centrifugal rotating cleaners. This operation is performed on steel pipe bends after hot bending to remove loose scales and sand. Ultimate Strength: The maximum stress that a material can sustain is called the Ultimate Strength. Under Bead Crack: It is a crack in the heat-affected zone or in previously welded weld metal Paralleling the underside contour of the deposited weld bead and usually not extending to the surface. Undercut: It is the unfilled groove made by the melting of base metal adjacent to the toe of a weld. Underground piping: Underground piping systems for drainage, or disposal of storm water or groundwater, use gravity flow at low pressure, often with entrained solids. Piping fittings used for these systems shall be designed to be as smooth as possible on their interior surfaces. When high peak flow volumes are involved, the design and construction of these systems are closely inter-related to sewer design. Unequal Tee: When the branch size is less than that of header size, reduced tee is used. Most common are tees with the same inlet and outlet sizes. Some of the industrial tees are Straight Tee, Reducing Tee, Double Branch Tee, Double Branch Reducing Tee, Conical Tee, Double Branch Conical Tee, Bullhead Tee, Conical Reducing Tee, Double Branch Conical Reducing Tee, Tangential Tee, and Double Branch Tangential Tee. Union: A union is similar to a coupling, except it is designed to allow quick and convenient disconnection of pipes for maintenance or fixture replacement. A union provides a simple transition, allowing easy connection or disconnection at any future time. A standard union pipe is made in three parts consisting of a nut, a female end, and a male end. When the female and male ends are joined, the nuts then provide the necessary pressure to seal the joint. Since the mating ends of the union are interchangeable, changing of a valve or other device can be achieved with a minimum loss of time. Pipe unions are essentially a type of flange connector, as discussed further below. Units: The measurement of physical quantities is one of the most important operations in engineering. Every quantity is measured in terms of some arbitrary, but internationally accepted units. There are four systems of Units, which are internationally accepted and commonly used. These are as follow: C.G.S. Units: In C.G.S. Units system, the fundamental unit of length, mass and time are Centimetre, Gram and Second respectively. The C.G.S. units are known as “Absolute Units” or “Physicists’ Units”. F.P.S. Units: In F.P.S. Units system, the fundamental unit of length, mass and time are Foot, Pound and Second respectively. M.K.S. Units: In M.K.S. Units system, the fundamental unit of length, mass and time are
Meter, Kilogram and Second respectively. The M.K.S. units are known as “Engineers’ Units”. India has adopted M.K.S Units for all purposes. Upper Transformation: It is the temperature at which transformation of the ferrite to austenite is completed during heating. Vacuum Systems Piping: Vacuum Systems are very thinner and lighter construction since the weight of the materials conveyed through the system is much less. Vacuum system shall be designed to be as smooth as possible on their interior surfaces. The fittings may be "belled" or expanded slightly in diameter, or otherwise shaped to accommodate insertion of pipe without forming a sharp interior ridge and by eliminating internal ridges, burrs, sharp turns, or other obstructions to smooth flow that might cause build-up of material into pipe blockages. Valves: Valve is equipment designed to stop or regulate flow of any fluid (liquid, gas, condensate, stem, slurry etc.) in its path. Valves are categorized depending on their applications like isolation, throttling and non-return. It is installed in the piping system based on its requirement. Various types of valves are available depending upon the type of construction as follows: Velocity Head: The velocity head (sometimes called "head due to velocity") of water moving with a given velocity, is the equivalent head through which it would have to fall to acquire the same velocity: or the head necessary merely to accelerate the water. Knowing the velocity, we can readily figure the velocity head from the simple formula: Vertical Position: It is a welding position in which the axis of the pipe is vertical with the welding being performed in the horizontal position .The pipe may or may not be rotated during welding. Viscosity: Viscosity is the internal friction of a liquid tending to reduce flow. Viscosity is the internal friction of a liquid tending to reduce flow. Viscosity is ascertained by an instrument termed a Viscosimeter, of which there are several makes, viz. Saybolt Universal; Tangliabue; Engler (used chiefly in Continental countries); Redwood (used in British Isles and Colonies). In the United States the Saybolt and Tangliabue instruments are in general use Viscosity is expressed as the number of seconds required for a definite volume of fluid under a arbitrary head to flow through a standardized aperture at constant temperature. Voids: It is a term generally applied to indicate the defects in paint, or welds. Water Equivalent: The water equivalent of a substance is defined as the quantity of water, which requires the same amount of heat required to raise the temperature of whole substance through 10 temperatures. Water Hammer: Whenever the discharge valve at the delivery end is suddenly closed or the running pump is closed due to power failure in a pipeline supplying water to a long distance point, the moving column of water is brought to a stop at the valve or a vacuum is created at the pump end of the line. Then the kinetic energy, equal to 1/2 MV2, contained in the column of water must be brought to the equilibrium stage. Hence to maintain the equilibrium the column of water compresses back and the pressure rises near the valve. From higher pressure point to the lower pressure point water rushes and acts upon the pipe wall and gives a hammer effect on the pipe repeatedly till equilibrium is reached. This hammer effect is called Water Hammer. Weave Bead: It is a type of a welding technology in which welding is done with oscillation of the electrode transverse to the axis of the weld. It is called a weave bead welding. Weight: It is the amount of pull, which the earth exerts upon a given body and it varies with the distance of the body from the centre of the earth. Thus the weight of the body varies with its position on the earth surface and thus, it is a force.
Weld ability: It is the ability of the metals to get welded under the specific condition of welding parameters. Weld Bead: It is the weld metal deposited during welding. Weld Decay: It is a term applied to areas adjacent to welds of a certain alloys, which have been subjected to inter-granular corrosion because of metallurgical changes in the alloys. Weld Metal Area: It is the area of the weld metal as measured on the cross section of a weld. Weld Metal: It is the portion of the weld, which is melted during welding either by melting of the electrode, filler wire, base metal or both. Weld Neck Flanges: Weld Neck Flanges are designed to be joined to a piping system by butt welding. They are expensive because of its long neck, but are preferred for high stresses to the pipe, reducing stress applications. The neck, or hub, transmits stress concentration at the base of the flange. The gradual transition of thickness from the base of the hub to the wall thickness at the butt weld provides important reinforcement of the flange. Turbulence and erosion are reduced due to the matching bore size of the pipe and flange. Welded Joint: It is a localized union of two or more members produced by the application of a welding process. Welder: He is a man who is capable of performing a manual or semiautomatic welding operation. Welder Qualification: This is the acceptance test determining the ability of a welder to make a satisfactory weld of the metals in the specified position of welding as per requirement of the codes. Welding Accessories: These are the tools, machines or other items used to achieve the weld, such as Electrode holder, Flexible power cable, Leather hand gloves, apron, Wire brush, chisel, hammer, Electrode holder etc. Welding current: The current, which flows through the electrical welding circuit during the making of the weld is called welding current. Welding Fit-up: It is a process of gas cutting, grinding, cleaning, and joining the two members to be welded together with tack welds after alignment and maintaining the welding joint design correctly. Welding Generator: It is the electrical current generator, which generates the D.C. power for welding. Welding Gloves: Welding gloves are specialized, highly-protective hand wear worn during material joining (welding) applications. They protect the welder's hands from high heat, molten metal, and flame while allowing for manual dexterity and movement of the fingers. Most welding gloves are made of heavy, thermally-insulating materials such as canvas, cotton, leather, metal and metal mesh, or wool. Welding Machine: The electrical or mechanical equipment used for welding is called welding machine. Welding Operator: He is a man who operates the welding machine. Welding Procedure qualification: It is a written qualified welding procedure with all of the essential, nonessential and supplementary essential variables, prepared to provide direction to the welder or welding operator for making production welds to codes requirements. Welding Procedure: It is a detailed document of methods and practices involved in the production of a weld, which includes the joint design, filler metals used, specification of metals to be welded, thickness of members and other parameters as per code requirements. Welding Process: It is a type of method of welding in, which describes how to produce the coalescence of the two members to be welded together.
Welding Rod: It is a rod or wire, consumable or no consumable, used for welding of the metals. Welding Sequence: It is the order or process of making a weld of the metals. Welding: Welding is a process where the material of the pipe or tube is itself partially melted in a carefully controlled manner to get the metals directly fused together. Wrought Iron: It is a refined iron in plastic state in a pudding furnace in which 3 percent of slag irregularities and 0.5 percent of carbon are mixed together with pure iron and other elements. Yield Point: This is the point of the first value of stress, in the stress-strain diagram, less than the maximum stress, at which the strain increase without any increase in the value of the stress. In other word, this is the point of the first value of stress at which the material cease offering resistance to a force and starts flowing in a permanent set without a noticeable increase in load. The value of the maximum first stress in a material having less unique yielding phenomenon than the maximum attainable stress at which any increase in strain occurs without any increase in the stress value. Yield stress: It is a value of the stress at which the material exhibits a permanent change in shape, size or dimension. The maximum stress at which the body exhibits a specified (limited) deviation from its original form or shape is called the Yield Stress.
1.9
List of Codes and Standards
Committees of leading engineering societies and standardization groups prepare various Codes and Standards, applicable to Design, fabrication and welding of piping systems. These are, generally, written with authenticity to establish the minimum requirements of quality and safety. Its main objective is to have Standardization and Safety. Periodic review of the standards by the committee is done and these are revised to incorporate the modified features based on the research and feedback from industry. Codes and Standards are essential Documents for Design, Engineering, Construction, Inspection and proper selection of Material of Piping Systems. It reduces cost, confusion and inconvenience. It is, hence, necessary that the latest editions of the codes and standards be referred for the design. American Iron and Steel Institute (AISI): These specify the material by its Chemical and Physical properties. ANSI Standards can identify the material when specific model of manufacture of the element is not specified. American National Standards Institute (ANSI): The American National Standards Institute (ANSI) is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. ANSI has five founding Engineering Societies, such as, American Institute of Electrical Engineers (AIEE); American Society of Mechanical Engineers (ASME); American Society of Civil Engineers (ASCE); American Institute of Mining Engineers (AIME); and American Society for Testing and Materials (ASTM). All Dimension Standards are covered under ANSI. The American National Standards Institute's standards used in the design of the Piping Systems are: ANSI A13.1 : Scheme for the Identification of Piping Systems ANSI A58.1 : Minimum Design Loads for Buildings and Other Structures ANSI B31.1 : Code for Power project piping ANSI B31.2 : Industrial Gas and Fuel Gas Piping ANSI B31.3 : Code for petroleum refinery piping ANSI B31.4 : Code for Liquid petroleum transportation piping system ANSI B31.5 : Refrigeration Piping. ANSI B31.6 : Chemical Industry Process Piping ANSI B31.8 : Gas Transmission and Distribution Piping Systems. ANSI B 31.9 : Building Services Piping ANSI B 31.11 : Slurry Transportation Piping System ANSI B 31.G : Manual for determining the remaining strength of corroded piping – a Supplement to ANSI B31 American Petroleum Institute (API): API produces standards, recommended practices, specifications, codes and technical publications, reports. Different API standards promote the use of safe, interchangeable equipment and operations through the use of proven, sound engineering practices and are listed as below: API RP14E: Recommended practice for offshore piping. API RP14C: Recommended practices for concerning required Safety devices for process components. API RP520: Recommended practice for design and installation of
Pressure Relieving Systems in Refineries, Part-I and Part-II. API RP521: Guide for Pressure Relief and Depressurising System. API 1102: Recommended practice for liquid petroleum cross-country pipeline, rail roads and highways API 1104: Specification for welding of cross-country pipeline and related facilities. API 1105: Bulletin on construction practices for oil and its producer’s pipelines API 1107: Recommended practice for maintenance of welding of pipelines American Society for Mechanical Engineers (ASME): ASME has adapted most of ANSI and ASTM Standards. This code covers piping connected to Boilers (Section I) to Pressures Vessels (section VIII), and to Nuclear Power Plant Components (Section-xi), which is frequently used by piping engineers and are listed below: SECTION-I; Rule for construction of Power Boiler SECTION-II; Material Part A Ferrous Material Specifications Part B Nonferrous Material Specifications Part C Specifications for Welding Rods, Electrodes and Filler Metals Part D Properties SECTION-III: General Requirements for Nuclear Vessels: Division 1 and Division 2. SECTION IV: Rules for Construction of Heating Boilers SECTION V: Non-destructive Examination SECTION VI: Recommended Rules for the Care and Operation Heating Boilers SECTION VII: Recommended Guidelines for the Care of Power Boilers SECTION VIII: Unfired Pressure Vessels: Rules for Construction of Pressure Vessels Division 1 Rules for Construction of High Pressure Vessel Division 2 Alternative Rules Division 3 Alternative Rules for Construction of High Pressure Vessel SECTION IX: Qualification Standard for Welding and Brazing Procedure, Welders, Brazers and Operators Qualifications SECTION X: Fibre-Reinforced Plastic Pressure Vessels SECTION XI: Rules for In-service Inspection of Nuclear Power Plant Components American Society of Testing and Materials (ASTM): All Material Standards are covered under ASTM, which consists of 16 sections on definitions and classifications of Materials of Construction and Test methods. Most of the ASTM Standards are adapted by ASME and are specified in ASME Section II. ASME Section II covers the various materials such as plates, castings, Pipe and tubes. The specification number has an Alphabetical prefix, "A" for ferrous and "B" for non-ferrous materials
and so on. ASTM also specifies standard practice for numbering metal and alloys as Unified Numbering System. Unified Numbering System (UNS) establishes 18 series numbers of metals and alloys. Each UNS number consists of a single letter prefix followed by 5 digits. In most cases the alphabet is suggestive of the family of the metal identified. American Welding Society (AWS): These standards provide information on the welding fundamentals; weld design, welder's training qualifications, testing and inspection of the welds and guidance on the application and use of welds. American Water Works Association (AWWA): These standards refer to the piping elements required for low-pressure water services. These are less stringent than other standards. Valves and Flanges required for large diameter water pipelines are covered under this standard and are referred rarely by piping engineers. British Standard (BS): British Standard may be substitutes for American Standards. Deutsches Institut für Normung e.V. (DIN): This is a German Institute for Standardization. German Institute for Standardization is the German national organization for standardization and is that country's ISO member body. DIN is a Registered German Association (e.V.). Japanese Industrial Standards (JIS): This specifies the standards used for industrial activities in Japan. The standardization process is coordinated by Japanese Industrial Standards Committee and published through Japanese Standards Association. Expansion Joint Manufacturers Association (EJMA): It is the Authority on Expansion Joints. The EJMA Standards are the authority on the proper selection and application of metallic bellows type expansion joints for safe and reliable piping and vessel installation. EJMA Standards is intended to provide users with a basic understanding of expansion joints and Heat Exchangers. It will also assist the user in communicating design requirements to the manufacturers and to properly install and maintain the expansion joint in service. Bureau of Indian Standards (BIS): Bureau of Indian Standards has so far not developed an Indian Standard for the design of Piping Systems. Indian Standards do not cover dimensions and material specifications under the same standard number. There are no groupings based on branch of engineering. So in India, we adopt only the American Standards. Indian Boilers & Regulation (IBR): This is an Indian Standard for design, fabrication and erection and Inspection of Boiler Piping. Manufacturers Standardization Society-Standard Practices (MSS-SP): It is Manufacturers Standardization Society. It develops Standard Practices of Valves and Fitting. These are published as advisory standards and are widely followed by manufacturers. National Association of Corrosion Engineers (NACE): NACE International is a professional organization for the corrosion control industry. NACE International is involved in every industry and area of corrosion prevention and control, from chemical processing and water systems, to transportation and infrastructure protection. NACE's main focus of activities includes cathode protection, coatings for industry and material selection for specific chemical resistance. NACE standards specify the pipe materials for sour and corrosive services of industries and these material grades are associated with ASME Sec. 2A standards also. NACE: Sulphide Stress Corrosion Cracking Resistant Metallic Material for oil field (MR-01-75) Equipment NACE: Testing of Metals for Resistance to Sulphide Stress Cracking at ambient (MR-01-77) Temperature
NACE RP-0286: Electrical Isolation of Catholically Protected Pipelines National Fire Protection Association (NFPA): This is Code, Standard and Recommended Practice for proper design of the Fire piping system. These Standards and specifications are very authentic and are frequently being used in piping industries for different purposes. It is, hence, necessary that the latest editions of the Codes and Standards shall be referred for the design. NFPA 70 : National Electric Code National Fire Code Volume 6 : Sprinklers, Fire Pumps, and Water Tank. National Fire Code Volume 8 : Portable and Manual Fire Control Equipment. International Organization for Standardization (ISO): International Organization for Standardization develops International Standards on a variety of subjects and many ISO standards are published every year. The full range of technical fields can be seen from the listing International Standards. European Committee for Standardization (CEN): The European Committee for Standardization (CEN) is a business facilitator in Europe, removing trade barriers for European industry and consumers. CEN is a major provider of European Standards and Technical Specifications. Canadian Standards Association (CSA): The Canadian Standards Association is an association serving business, industry, government and consumers in Canada and the global marketplace. They work in Canada and around the world to develop standards that address real needs, such as enhancing public safety and health and advancing the quality of life and helping to preserve the environment. Society of Automotive Engineers (SAE): SAE International is a global association of engineers and technical experts in the aerospace, automotive and commercial-vehicle industries. United States Military Standard (A-A): A United States Defence Standard, often called a military standard, "MIL-STD", "MIL-SPEC", or "MilSpecs", is used to help achieve standardization objectives by the U.S. Department of Defence. Standardization is beneficial in achieving interoperability; ensuring products meet certain requirements, commonality, reliability, total cost of ownership, compatibility with logistics systems, and similar defence-related objectives.
1.10
VENDORS AND M ANUFACTURER PIPES :
Ameron International, Geldermalsen, Netherlands. Anderson Hydraulics, Aberdeen, UK, British Steel Tubes & Pipes, Northamptonshire, UK. British Steel Tubular Supply Services, Northamptonshire, UK. Dalamine, Italy, Fax: 0031 345 574903 Itochu, Japan. Kawasaki Steel, Japan Mannesmann Rohren Works, Germany.
Marubeni, Japan. Mitsui, Japan NIPPON Steel, Japan NKK, Japan NSC, Japan. Sidereca, Argentina Sumitomo Corporation, Japan. Thyssen Stahlunion, GmbH (Germany) Vallource & Mannesmann, Germany
FLANGE: Anderson Hydraulics, Aberdeen, UK. Ani Aurora PLC, Yorkshire, UK. Austin Stround, U.K. BG Technomarine System Ltd, UK. BSL Tubes et Raccords sa, France. Corposider, Italy. Echjay Industries Ltd., India. Galperti, Itali London Forged Fittings, UK.
Melesi, Italy Metal Forging, India MGI, France Nicola Galperi, Italy. Paramount Forging, India Punjab steeal, India Schulz Export, W. Germany. Sumitomo, Japan Technofine, India
FITTINGS : Anderson Hydraulics, Aberdeen, UK. Ani Aurora PLC, Yorkshire, UK. BG Technomarine System Ltd, UK. British Steel Tubular Supply Services, Northamptonshire, UK BSL Tubes et Raccords sa, France. Corposider, Italy. Fittinox, Italy Gam Raccordi, Italy Igwara, India Corposider spa, Italy.
IHF, India Mega, spa. Italy Schulz Export, GmbH Germany, Trauvey & Cauvin, France. Nichimen, Japan Pipeline International, U.K. Raccordi Forgaiti, Italy Schulz Germany, UK. Sumitomo, Japan Techno Forged, U.K. Benken, Japan
VALVES : Akay, Hubly ANDERSON G REENWOOD , UK. Anderson Hydraulics, Aberdeen, UK. Ani Aurora PLC, Yorkshire, UK. B.D.K Marketing, Hubly Babcock Flow Controls Balon Corporation BALON, USA Bately Valvve Co Ltd, West Yorkshire, UK. BI Thornton Ltd.,
KTM, JAPAN L&T AUDCO, MADRAS LB Bentley Ltd. Gloucester shire, UK. MAPEGAZ, FRANCE OMB, ITALY. RONA, T K VALVES, ABUDHABI. OMB SPA, ITALI OMS SALERI, ITALY
Yorkshire, UK.
ORION, ITALI PERAIR, ITAALI PETROL VALVES,
Bifold Co Ltd,
(Manufacturing) Manchester, UK. Blakeborough Control V.aves, Yorkshire UK. Breda Energia-Sesto Industria, Milano, ITALY. BVUK Ltd, Leicester, UK. FLOW CONTROL, CANADA GROOVE ITALIA, SPA GROVE, ITALY KITZ, JAPAN
PLATES
ITALI PRECISION ENGG.,NASIK PROCEEP, AHMEDABAD ROBERT CORT, UK RONA VALVES, BELGIUM SAKHI ENGRS, MUMBAI T.K. VALVES, ABUDABI VALVINOX VITAS, ITALI WALTHER WEIR, SPAIN ZUMOX, MUMBAI
FOR PRESSURE VESSELS :
BRITISH STEEL DILLINGER, PREUSSAY GmbH IEC PIPING, ITALI IISCO, INDIA INCO ALLOYS, UK KOBE STEELS LTD., JAPAN MAHER ALLOYS LTD., SINGAPORE
M/S DALMINE, ITALY. MITSUBISHI METAL, JAPAN PHILIP CARNES SAIL, INDIA THYSSEN, FRANCE TISCO, INDIA VDM, GERMANY
GASKET: ACORN SEALS LTD, DALGETY BAY , UK. Advanced Products (Seals & Gasket), UK. IGP LTD.
Madras Industrial Products, MOORSIDE, UK SEVAL, ITALI
N UTS & BOLTS : BEA, ITALI BOLT MASTER (I) LTD., INDIA HARDWIN FASTENERS
OME, ITALI SANDEEP ENGG. INDIA SYNDICATE ENGG. INDIA
I NSULATION M ATERIAL: AARON SEALS, Cambridge shire UK. Anderson Hydraulics, Aberdeen, UK. ARMSTRONG INSULATION PRODUCTS, UK. BRITISH STEEL TUBULAR SUPPLY SERVICES , NORTHAMPTONSHIRE, UK FLAME ARRESTOR: BSL TUBES ET RACCORDS SA, Cedex, France,
H OSE: AARON SEALS, Huntington, Cambridge shire UK., Anderson Hydraulics, Aberdeen, UK. BAND-IT CO LTD, Chesterfield, Derbyshire, UK., NON-DESTRUCTIVE TESTING: ABBOT GROUP PLC, ABERDEEN UK., ACIERIES HACHETTE & DRIOUT, Saint-Dizzier, France., AEA SONOMATIC, Aberdeen UK., AGFA GEVAERT INDIA LTD., Marine Lines, Mumbai, BG TECNOMARINE SYSTEM LTD, Arbroath, UK, BHABHA ATOMIC RESEARCH CENTER, Trombay, Mumbai BLUE STAR LTD, Prabhadevi, Mumbai-400025 C.Z. INSTRUMENTS INDIA LTD., Sir V. Thakeray Marg, Mumbai-400020
H EAT TREATMENT: ABBOT GROUP PLC, Aberdeen UK., ACIERIES HACHETTE & DRIOUT, Saint-Dizzier, France. Industrial Marine & oil field Service, Ambal Doshi Marg, Mumai-400023 Mathbin Scientifics, 301/10-A, Ranjit Nagar Complex, New Delhi-110 008 Metallurgical Services, Ghatkopar, Mumbai-400 086, TEL: 585241 NDT Appliances Pvt. Ltd., 59, Suren Sarkar Road, Calcutta-700 010 Pioneer Equipment Co. Pvt. Ltd., 432, Padra Road, Broda-390 005 Pradeep Metal Treatment Chemical Pvt. Ltd., Wagle Estate Thane-400 604 Relsonics, Khatani Textile Industries Compound, Kurla, Mumbai. SGS India Pvt. Ltd., SGS House, Nauroji Furdosji Road, Colaba, Mumbai-400039 Southern Dynamics, Ramaswami Street, Manady, Madras-600 001 Test Equipment, 102,Chittaranjan Park, New Delhi-110 019
Vibtronics Pvt. Ltd., Nasyani Estate, Halav Bridge, Kurla, Mumbai-400 070 X-ray Associates Mfg. Co., 124, S.V. Road, Jogeshwari, Mumbai-400 060 X-Ray Engg. Co. (P) Ltd., Off Vidyanagari Marg,, Kalina, Mumbai-400 098
NDT EQUIPMENTS SERVICES : ANDREX RADIATION PRODUCTS AS, COPENHAGEN S, DENMARK East west Enterprises Ltd., 33, Brabourne Road, Calcutta-700 001, India Industrial Testing Ltd., Belington Road, Leighton Buzzard, Bedford Shire. Industrial X-Ray System, Hum berg 68, West Germany Magnafield Controls, By Lane, Deccan Gymkhana, POOna-411 004, India Magnaflux Ltd., South Dorcan Industrial Estate, Swindon SN3 5HE-U.K Philips GmbH Werll Fur Messtechrik Radiation Product Division, 40, North Avenue, Burlington, Mass-01803 Vito Sonics Ltd., Marsh gab Drive Hertford, Herts, England
I NSTRUMENTS & C ONTROLS : ABB-KENT TAYLOR, INDIA Able Instruments & Controls Ltd, UK., Agema Infrared Systems Ltd, Bedfordshire UK., AMETEK –PMT, Feasterville, USA, ANDERSON, USA ASCHROFT, USA AUDCO, INDIA BAKER CAC, USA BELLS, INDIA BLAKEBOROUGH, UK BOPP & REUTHER, GERMANY BOURDEN SEDOME CCI, USA DANFOSS, INDIA DANIEL USA DELTA CONTROLS, UK
EUROTHEMCHESSEL, INDIA FISHER ROSEMOUNT, INDIA FISHER, USA/FRANCE FOXBORO, INDIA GALPERTI, ITALI GMA, USA HONEYWELL, INDIA ITT BARTON, UK FMC, INDIA MASONEILAN, USA/FRANCE MELESI, ITALI SWITZER, INDIA SWTZER, INDIA COOPERCAMERON, USA., WIKA, GERMANY YOKOGAWA BLUE STAR, INDIA
1.11
Book References
ADSCO Manufacturing LLC, Expansion Joints Catalogue 1196, Buffalo, New York. American Institute of Steel Construction, Inc., Manual of Steel Construction, 8th Edition, Chicago, Illinois. Asahi/ America, Inc., Piping Systems Product Bulletin P-97/A, Malden, Massachusetts. ASHRAE Handbook, Heating, Ventilating, and Air-Conditioning, SYSTEMS AND EQUIPT, Atlanta, Georgia. Assini, John, “Welded Fittings and Flanges”, Southern Engg. Cameron Hydraulic Data Handbook, Ingersoll-Rand Company. Can ham, W.G., and Hagerman, JR, “Reduce Piping connection Costs”, Hydrocarbon Processing. Chemical Engineering – Desk book Issue, “Valves”. Chemical Resistance Tables, Modern Plastics Encyclopedia, McGraw-Hill, New York. CMB Industries, FEBCO Backflow Prevention Service Information Model 765 Pressure Vacuum Breaker Assembly Catalog, Fresno, California. Compass Corrosion Guide, La Mesa, California, 1983. Corrosion Data Survey, Metals Section, 6th Edition, National Association of Corrosion Engineers, Houston, Texas. Corrosion Data Survey, Non-metals Section, 5th Edition, National Association of Corrosion Engineers, Houston, Texas. Crane Company, “Flow of fluids through Valves, Fittings, and Pipe”, Technical Paper No. 410. Crane Company, Cast Steel Valves, Crane Valve Catalog, Joliet, Illinois. Crane Company, Flow of Fluids, Technical Paper 410, Joliet, Illinois. Crane Valves, Cast Steel Valves, Crane Valves, Engineering Data, Crane/Resistoflex, “Plastic Lined Piping Products Engineering Manual”. Design of Machine Elements, by Spotts, M.F.- for U-Loop Compensator Formula. Dresser Industries, Inc., Style 38 Dresse r Couplings for Steel Pipe Sizes, Sizes and Specifications, Form 877-0C, Bradford, Pennsylvania. Ernest F. Braler and Horace W. King, Handbook of Hydraulics, 6th Ed for “Water hammer”. Evans, Frank L. “Special Report on valves”, Hydrocarbon Processing Volume 40.No.7 Fike Metal Products, Rupture Discs & Explosion Protection, Fluid Controls Institute, Bulletin FCI 62-1 Handbook of PVC Pipe, 3rd Edition, Uni-Bell Plastic Pipe Association, Dallas, Texas. Hugely, Dale, “Acceleration Effect is Major Factor in pump Feed System”, Petroleum Equipment and Services. Hydraulic Institute Engineering Data Book, Hydraulic Institute, Cleveland, Ohio. Hydraulic Institute Standards, 14th Edition, Hydraulic Institute, Cleveland, Ohio. Loudon, D.E., “Requirements for Safe Discharge of Hydrocarbons to Atmosphere”. API Proceedings, Vol. 43 (III) (1963) Pages 418 – 433. Miller, J.E, “Experimental Investigation of Plunger Pump Suction Requirements”, Petroleum Mechanical Engineering Conference, Los Angles, California, September.
Phillip A. Schweitzer, Corrosion, and Corrosion Protection Handbook, Marcel Dekker, Inc., New York. Piping Design and Engineering, 5th Ed., ITT Grinnell Industrial Piping, Providence, Rhode Island, for Expansion Loops Products Engineering Manual,” Marion, North Carolina. RMA, "The Hose Handbook," Schweitzer, Corrosion-Resistant Piping Systems. Tube Turns Corporation, “Line Expansion and Flexibility”, Bulletin TT 809. Tube Turns division of Chemetron Corporation Piping Engineering Handbook. Tuttle, R.N. “Selection of Materials Designed for Use in a Sour Gas Environment”, Material Protection, Volume 9 No. 4. Tyler & Hick s, Editor in Chief, Standard Handbook of Engineering Calculations, 3rd Ed. for “Water hammer”.
2 Piping Materials Materials science investigates the relationship between the structure of materials at atomic or molecular scales and their macroscopic properties. It deals with fundamental properties and characteristics of materials. Process piping systems include pipe and appurtenances. Materials selection is an optimization process, and the material selected for an application must be chosen for the sum of its properties. Considerations include quality, cost, availability, and joining. Key material evaluation factors are strength, ductility, toughness, and corrosion resistance. Selection of material for any given application depends on service conditions, environmental conditions, corrosion resistance, and stress cracking resistance, scaling, thermal or mechanical fatigue, creep, notch, toughness and metallurgical instability at low, normal or elevated temperature. These characteristics, taken together and related through the laws of thermodynamics, govern a material’s microstructure, and thus its properties.
2.1
Materials Classification
The materials are classified into following categories, such as, Iron, Iron alloys, Carbon steel, Alloy Steel, Stainless Steel, Polymers, Ceramics, Glass, and Refractory based. (1) Iron: It is also called Ferrite (Alpha iron) or (α-Fe). Ferrite (Alpha iron) or (α-Fe) is a material termed for pure Iron or a solid solution with iron as the main constituent. It is the component which gives steel and cast iron their magnetic properties, and is the classic example of a ferromagnetic material and is considered a pure iron. It has strength of 280 N/mm2 and a hardness of approximately 80 Brinell. Properties of iron are greatly dependent on the quantity of carbon available in iron. When the carbon content is very low, the iron is soft and when carbon quantity is more the iron is very hard, brittle, and strong. So carbon content is taken as basis for classification of iron. It is classified mainly in three groups, such as, Pure Irons; Commercial Irons and Wrought Irons. (i) Pure Irons: Pure irons contain 99.99% of iron. The carbon is always present in irons. Pure iron is the purest form of iron in iron carbon alloys. The carbon contents in irons are very negligible and have negligible effect on properties. It is very costly to produce the purest form of irons. Carbonyl iron and electrolytic irons are the pure form of Irons. They are used especially where very high magnetic permeability is required such as transformer cores and in research. In pure iron, ferrite is stable below 910 °C (1,670 °F) and above 910 °C, the austenite (gamma-iron), the face- centre cubic form of iron, is stable above 1,390 °C (2,530 °F) up to the melting point at 1,539 °C (2,802 °F). Ferrite above the critical temperature A2, the curie temperature of 771 °C (1,044 K; 1,420 °F), is paramagnetic rather than ferromagnetic, is beta ferrite or beta iron (β-Fe). The term beta iron is rarely used because it is identical to α-Fe. A very small amount of carbon can be dissolved in ferrite; the maximum solubility is about 0.02 by wt % at 723 °C (1,333 °F) and 0.005% carbon at 0 °C (32 °F). This is because carbon dissolves in iron interstitially, with the carbon atoms being about twice the diameter of the interstitial "holes", so that each carbon atom is surrounded by a strong local strain bond. The structure for low carbon content steel is stabilized. 723 °C (1,333 °F) is the minimum temperature where iron-carbon austenite (0.8 wt % C) is stable and at this temperature there is a eutectoid reaction between ferrite, austenite and cementite. Ferrite (Alpha iron) (α-Fe): Ferrite (Alpha iron) (α-Fe) is a material termed for Iron or a solid solution with Iron as the main constituent; with a body centre cubic crystal. It is expensive type of iron. It is used in special purpose where superior ductility, corrosion resistance, electrical conductivity, or Magnetic permeability is required. Ingot irons are the commercial irons. It is used in deep drawn parts and embedded wires where high formability is required (ii) Wrought Irons (Cast Iron): Wrought irons are also the purest form of irons. But contain 3% of slag particles distributed in an Iron Matrix. Slag consists of oxides and silicates of calcium, magnesium, manganese, and iron. The slag fibres improve strength, fatigue resistance, and corrosion resistance of iron. It is mainly used for oil, water, LP and steam pipelines. (iii) Iron Alloy (Carbon Steel/Alloy Steel): An Iron alloy is a mixture of two or more elements in solid solution of iron in which the major component is Iron as base metal. Combining different ratios of alloying metals as alloys modifies the properties of pure metals to produce desirable characteristics. The aim of making alloys is generally to make them less brittle, harder, and resistant to corrosion. The alloys of iron alloy are cast iron, carbon steel, stainless steel, alloy steel and tool steel. Iron alloy with various proportions of carbon gives low, mid and high carbon steels. Increase of carbon levels reduces the ductility and toughness. The addition of more silicon
will produce cast irons, while the addition of chromium, nickel and molybdenum (more than 10%) results in stainless steels. Other significant Iron alloys are those of aluminium, titanium, copper and magnesium. The Iron alloys of aluminium, titanium and magnesium are valued for their high strength-to-weight ratios; magnesium can also provide electromagnetic shielding. These materials are ideal for situations where high strength-to-weight ratio is more important than material cost. (2) Carbon Steel: Carbon Steel is an iron alloy whose major component is iron with carbon content between 0.02% and 2.14% by mass. Carbon Steel is that iron with the main interstitial alloying constituent carbon. The Carbon Steel pipe is strong, ductile, weld able, machine able, reasonably durable and is cheaper than pipe made from other alloying materials. Carbon steels temper readily and have poor creep resistance above 350 0C. If carbon steel pipe meet the requirements of pressure, temperature, corrosion resistance and hygiene, it is best choice. It is the most common and economical metal used in piping industry. It will readily rust (corrode) in ambient atmospheres. Hardness and strength increase with increasing carbon content. Coefficient of Expansion of Carbon Steel is 0.1182 inch per 0C and Melting Point is 1530 0C. Any combination of hardness, strength and ductility can be obtained in steels by suitably controlling the carbon content, alloying elements and head treatment. Steels can be subjected to all kinds of fabrication processes such as chinning, forming, cold rolling, hot working, casting, cutting and welding. It will also become brittle with prolonged contact with alkaline or strong caustic fluids and contact with acid accelerates corrosion. It may react directly with hydrogen sulphide gas. Classification of Carbon Steel: Carbon Steel is most useful material in piping industry. Iron carbon alloys containing up to 2 % of carbon are called carbon steels. In addition, carbon steels also contain small amount of sulphur, phosphorus, silicon, and manganese. The carbon content as well as alloying elements mainly determines mechanical properties of steels. Carbon Steels have some drawbacks such as poor scaling resistance, low corrosion resistance, high specific gravity, low electrical conductivity, and low magnetic permeability. Based on carbon content, the steels have been classified into three groups, such as, Low carbon steels; Medium carbon steels and High carbon steels. (i) Low Carbon Steels (Mild Steel): Low Carbon Steels contains approximately 0.05% to 0.3% carbon by weight and suffer from yield-point run-out where the material has two yield points. The first yield point (upper yield point) is higher than the second and it drops dramatically after the upper yield point. They possess low strength, good machine ability, high ductility, high formability, and high welding suitability. Mild Steel is the most common form of steel which provides material properties that are acceptable for many applications. Mild Steel contains 0.16% to 0.29% carbon and consists mostly of ferrite, with increasing amounts of pearlite, i. e. a fine lamellar structure of ferrite and cementite as the carbon content is increased. Therefore, it is neither brittle nor ductile. Mild steel has a relatively low tensile strength, but it is cheap and malleable and surface hardness can be increased through carburizing. The density of mild steel is approximately 7.85 g/cm3 (7850 kg/m3 or 0.284 lb/in3) and the Young's modulus is 210 GPa (30,000,000 psi). (ii) Medium Carbon Steels (Carbon Steel): Medium Carbon Steels (Ductile Iron) contain 0.3 to 0.6 % carbons by weight, which balances ductility and strength and has good wear resistance. These steels have high strength after heat treatment. But they are less ductile, low machine ability and low welding ability as compared to low carbon steels. It is also called carbon steel or ductile iron, which is a slightly hard, non-malleable ferrous metal that must be moulded into the various component shapes easily. It is used for piping applications requiring strength, shock resistance, and machining and also used for large parts, forging and automotive components.
It has good resistance to general corrosion, but reacts readily with hydrogen sulphide. Ductile Iron pipe is also seldom employed now days. Mainly carbon is responsible for the mechanical properties of steels. Manganese provides a minimum hardness and strength after working. Silicon is present in steels when the steel is oxidized and provides temperature resistance property to steel. Sulphur and phosphorus are always present in steels of impurities. (iii) High Carbon Steels: High carbon steels contain carbon more than 0.6% by weight. So carbon content between 0.6 to 2.0% comes in these groups. They possess high hardness and high wear resistance after heat treatment. They are less ductile and more brittle as compared to low carbon steels. High Carbon Steels can successfully undergo heat-treatment. Trace amounts of sulphur (0.05%) in steel make it red-short. High Carbon Steels is very strong, used for springs and high-strength wires. It is also called Ultra-High Carbon Steel and it can be tempered to great hardness. It is used for special non-industrial purposes like knives, axles or punches. (iv) Cast Iron (Wrought Iron): The steel with carbon content above 2.0% is considered cast iron. It is brittle and has less strength. Wrought Iron is made from cast-iron and ductile iron. The principal uses are for water, gas and sewage lines piping that are laid underground in the Public Health Engineering Department. Wrought iron pipe is seldom employed now days. Table: Composition range of Carbon Steels Serial No.
Element
Percent by weight
1 2 3
Carbon
4 5
Silicon
0.3 to 0.6 0.30 1.00 0.0 to 0.30 0.04 max 0.04 max Balance
6
Manganese
Sulphur phosphorus
to
Iron (3) Alloy Steel: Alloy steels are defined as a carbon steels to which one or more alloying elements are added to get some beneficial property of the alloy steel. The commonly added alloying elements are chromium nickel, manganese, molybdenum, silicon, vanadium, tungsten, copper, aluminium and boron. Alloy steels possess the improved properties over carbon steels due to presence of the alloying element. Alloy steels can have higher hardness, strength, and toughness as compared to plain Carbon Steels. Alloy steels can have higher hardened ability, which plays significant role in heat treatment. Alloy steels have higher temper ability and they retain cheer hardness and strength at elevated temperatures (deep strength) as compared to carbon steels. Alloy steels possess high hardness (red hardness) of temperature up to 600 0C due to the presence of alloy carbides. Alloy steels have higher corrosion resistance and oxidation resistance. Different alloying elements have different functions to perform when added to steel. Therefore, alloy steels containing different alloying elements are used for different applications. Alloy Steel is used for its strong resistance to
certain corrosive chemicals and higher service temperature. Alloy Steel, more commonly, prescribed are ASTM A335, Gr. P5, P9, P11, and P22 and are used for applications above 315 0C. Corrosion resistances are the same for Alloy Steel and Carbon Steel. As the alloy content increases, the heat treatment plays an important effect on microstructure and mechanical properties. However, the effect of cooling rate (method of cooling) in heat treatment varies significantly on the hardness & microstructure of the materials. (4) Stainless Steel (Nickel and Nickel Alloys): Stainless steel is the product of steel alloyed with chromium and to a lesser extent nickel. Other elements such as molybdenum, copper, manganese and silicon are included in different proportions as part of the alloy for various steel types. Chromium is the primary additive that makes steel “stainless”. Stainless steels containing higher amounts of chromium and nickel provide good scaling, oxidation and corrosion resistance at high temperatures. Nickel is used for its strong resistance to certain corrosive chemicals. Nickel-base alloys have high strength and corrosion resistance at temperatures up to 750 0C. Typical alloys of this group are Nichrome, Kanthol, Hastelloy, and Inconel. In addition to creep strength, high nickel-chromium alloys possess excellent thermal shock resistance and high electrical resistance. The most common types of stainless steel used for liquid process applications are A 304, A 304L, A 312 and A 316. Stainless steel is not totally corrosion resistant as chemicals such as sodium bisulphide, ferric chloride, ozone, and hydrochloric acid attack stainless steel successfully. The formation of chromium carbide along the grain boundaries leads to instability and is known as intergranular carbide precipitation. Whenever common Austenitic Stainless Steels are exposed to a higher temperature range from 900 0F to 15000 F, the carbon tends to defuse to the grain boundaries and combine with chromium to form chromium carbide particles. Precipitation of chromium carbide particles at the grain boundaries reduces the resistance of the stainless steel to certain corrosion substance and hence it got corroded at the grain boundaries known as inter-granular corrosion. This process of chromium carbide formation is applicable to the heat-affected zone of the welds due to tremendous heat developed during welding. Some type of Stainless Steel such, as A 301 & A 302 are more susceptible to inter-granular corrosion than A 304 because they have 0.15% maximum carbon. A 304 have 0.08% maximum carbon. Inter-granular corrosion is slightly restarted by increasing the percentage composition of chromium or molybdenum content as in case of A 309, A 310 & A 316. Inter-granular corrosion may be prevented by adding columbium, columbium and tantalum as in case of A 318, A 347 & A 348 and also by adding titanium as in case of A 321. Suitable annealing heat treatment between 18500 F and 20500 F and quenching in water or water spray after the final fabrication of the piping components may also prevent inter-granular corrosion. Stainless steel with 0.03 percent maximum carbon content is called extra low carbon grade stainless steels but the rate of chromium carbide formation is very slow and amount is in decimal. However the mechanical properties of all these stainless steel are not impaired due to chromium carbide precipitation. To avoid inter-granular corrosion, some precautions shall be taken during welding so that much heat is not developed and weld is cooled very fast. The theory is achieved by (1) use of small diameter electrode (2) use of low welding current (3) by stringer-bead welding (not weaving welding) (4) use of chill bars in the fixtures for welding (5) Immediate fast cooling of the weld by blowing air or spraying water (6) by using extra-low carbon content grade electrodes or filler (i.e., 0.03% maximum carbon content). Stainless steels are most versatile materials used for piping. The greatest advantage of stainless steel over plain carbon steel and alloy steels is that it provides high resistance to corrosion in most of the environments and fluid service. The corrosion resistance of stainless steel is derived from the presence of oxide films on the surface.
These oxide films are very thin, stable, and continuous to be attacked by the corrosion. The most important constituent of this film is Chromium oxide (Cr2 O3), which is obtained from the Chromium element present in the alloy more than 12%. Corrosion resistance of stainless steel increases with increase in the Chromium content. Nickel present in stainless steel improves ductility and impact strength. Nickel also increases the corrosion resistance against Neutral chloride solution and weak oxidizing acids. Nickel may be added up to 20% to stainless steel. Molybdenum present in stainless steel improves their resistance to sulphuric, sulphurous, and organic acids. It also increases corrosion resistance to halogen salts and resistance to pitting to salt water. Manganese content up to 1 to 2 % in stainless steel is beneficial to increase the hot workability. Carbon is kept low in stainless steel and does not exceed 0.2%. Types of Stainless Steels: Various alloying elements such as Chromium and Nickel determine the structure of stainless steel. Based on the structures of stainless steel, it is differentiated in three types as below: (1) Ferritic Stainless Steel: Ferritic stainless steel contains Chromium between 12 to 14% and Carbon between 0.08 to 0.2%. The structure of this steel is of ferritic phase, which cannot be hardened by heat treatment. High chromium ferritic stainless steel has high corrosion and scaling resistance. They are widely used as furnace parts. AISI 430 group of stainless steel is ferritic stainless steel. This type of steel is consumed maximum in the industry. (2) Martensitic Stainless steels: Martensitic stainless steels contain Chromium 12 to 14% and Carbon 0.1 to 1.2%. The microstructure of the martensitic stainless steel is hard-martensitic phase after hardening. The most common martensitic stainless steel of this group is A 410, 416 and 403. Stainless steel containing 12 to 14% Chromium and 0.3% carbon are widely used for table cutlery, tools and equipment. Stainless steel containing carbon more than 0.2% and Chromium between 16 to 18% is used as springs, ball bearings, valves and instruments under high temperature service and corrosive condition. (3) Austenitic Stainless Steel: Austenitic stainless steels contain Chromium 16 to 24% and Nickel between 8 to 22% Carbon less than 0.2%. The most common Austenitic stainless steel of this group is A 303F, 304,304L, 302, 316, 321, 347, 348, and 403. Stainless steel containing 18% Chromium, 8% Nickel and 0.2% carbon are widely used in piping in the industry. In 18/8 stainless steel carbons content vary according to the requirements and are classified accordingly as below: (4) Precipitation Hardening Stainless Steel: Precipitation Hardening Stainless Steels possesses very high strength at room temperature as well as at 540 0 C. High strength is obtained due to precipitation of copper, Aluminium, Nitrogen and Columbium by a suitable heat treatment. These steels are used as a material of skins, nibs, bulkheads, and other structural components in aircraft and missile industries. Advantage of Stainless Steel: Stainless Steels are widely used due to their high corrosion resistance wide range of mechanical properties such as high hardness, high strength, good fatiguestrength, excellent notch-sensitivity, and high ductility. Some of the properties are described below: Forming: Stainless steels have very high forming characteristic. Welding: The welding of stainless steel is more difficult as compared to other steels because of possible reaction of Chromium with carbon and oxygen at welding temperature. Oxy-acetylene gas welding is not advisable for stainless steels because of the above reaction. Tungsten-Inert Gas welding or suitable electrode welding is used for welding of stainless steels. Plasma or Electron Beam welding is suitable for fully ferritic high chromium stainless steels.
Oxidation Resistance: In oxidizing atmosphere, chromium of stainless steel is exposed to the oxygen and gets oxidized to form Cr2 O3. This process depletes chromium and hence higher amount of chromium is required to maintain this film. Cryogenic-Temperature Behaviour: It has been seen that many metals, which are ductile at room temperature, fail by brittleness at low temperature. Austenitic stainless steels are most suitable for use at low temperature (cryogenic Temperature) up to –2500 C. Type A 304, 304 L, 310 and 347 grades are most suitable. Corrosion Resistance: Stainless steel develops a film of Chromium Oxide on its surface due to reaction of chromium with oxygen. Also the passivity of the chromium oxide film increases with the addition of Nickel to the Iron. Chromium alloy addition of nickel increases the resistance of corrosion in presence of Neutral chloride solution and weak oxidizing acids. Corrosion resistance to chemical attack can be considerably increases by addition of 2 to 4 % Molybdenum. It also increases the corrosion resistance against the Organic Acids and vapours and also to Halogen Compounds. The different grades of stainless steels possess different corrosion resistance in different media as given in the Table: Table: Application of Stainless Steels in different fluid service S. Stainless Fluids Cost of No. Steel Material Grades 1 A 410 & Rural Atmosphere, Fresh Cheap 430 Water, Inorganic Acid, 2
3
A 316 & Chloride Contamination, Costly 317 Marine Atmosphere, Salt Water, Soils, Sulphuric Acid (concentration less than 20% and greater than 85%), Hydrochloric acid (cold up to 2% concentration), Sulphuric acid flue gas containing sulphur dioxide, Sulphide pulps, Organic Acid (At higher temp.), Cleaner product (at room temp.)Acid salts, Strong Sodium chloride (3N) (at temp. above 70 0C) A 302 & Marine Atmosphere, Costly 304 Sulphuric acid & Ferric Sulphate, Soils, Nitric Acid (up to 65% concentration & 110 0C), Organic acid (at
room temp.), Neutral & Alkaline salts, Strong Sodium Chloride (3N) at temperature up to 520C Table: Composition, Properties, and uses of Stainless Steels COMPOSITION, PROPERTIES AND USES OF STAINLESS STEELS S. AISI Composition Percent General No Type C Mn Si Cr Ni Oth. Properties and uses Max Max Max 1 2 3 4 5 6 7 8 9 A- Martensitic 1
403
0.15 1
0.5 12- 13
2
410
0.15 1
1
1214
3
414
0.15 1
1
1214
4
416
0.15 1.2 1
1214
5
420
>.15 1
1214
1
-
Used for highly stressed parts. Turbine and compressor blades. - Low price, general purpose, high strength and abrasion resistance. 1-2 Better corrosion resistance than Type 410, used in springs, knife blades etc. - 0.15S Free machining min grade 0.15Se min - Higher carbon to provide greater hardness to cutlery, surgical Instruments, valves ball
6
431
0.2 1
1
7
440A 0.65 1
1
8
440B 0.85 1
1
9
440C 1.1 1
1
bearings, etc. 15- 1-2 Increased 17 corrosion resistance and high strength. 16- - 0.75Mo --18 16- - 0.75 High carbon 18 Mo content and harden-ability. High hardness. 16- - 0.75 Toughness, 18 Mo surgical instruments, cutlery, bearings valves.
B-Ferritic 10 405
0.08 1
1
12- 14
11 430
0.12 1
1
14- 18
12 430F 0.12 1.2 1
14- 18
13 442
18- 23
0.2 1
1
0.1- Fully ferritic, 0.3 non-hardening A1 Greatest tonnage, produced used mostly in automotive trim, high resistance to nitric acid and other highly oxidizing maid. 0.15 Free machining S grade min 0.15 S min High temperature service in high sulphur atmosphere
14 446
0.2 1.5 1
23- 27
0.25 High corrosion N and scaling max resistance up to 1100° C
C-Austenitic 15 201
0.15 5-7 1
16 202
0.15 7-10 1
17 301
0.15 2
1
18 302
0.15 2
1
16- 3-5 0.25 N A portion of 18 max nickel has been replaced by manganese and nitrogen. 17- 4-6 0.25 N A portion of 19 max nickel has been replaced by manganese and nitrogen. 16- 6-8 High strength 18 after cold work. 17- 8- 19 10
19 302B 0.15 2
2-3 17- 8- 19 10
20 303F 0.15 2
1
1719
21 304
1
1820
0.8 2
18:8 generally utility, easily worked, lower rate of work hardening than type 301
Higher silicon increases resistance to Scaling at high temperatures 8- 0.15 S Free machining 10 min grade 0.15 Se min 8- General 12 corrosion resistance in chemical industry requiring
welded Fabrication; susceptible to inter-granular corrosion. 22 304 L 0.03 2
1
18- 8- 20 12
23 305
0.12 2
1
17- 10- 19 13
24 308
0.08 2
1
19- 10- 21 12
25 309
0.2 2
1
22- 12- 24 15
26 309 S 0.08 2
1
22- 15- 24 15
27 310
1-5 24- 19- 26 22
0.25 2
Extra lowcarbon, no danger of intergranular corrosion during Service, welding or stress-relieving when used below 430°C. Low rate of work hardening, favourable to severe cold forming such as spinning. Used as welding rods for welding other stainless steels. Greater strength and scaling resistance at high temperatures up to 1050°C. Less danger of carbide precipitation in welding. Increased strength and oxidation resistance at elevated Temperatures
28 314
0.25 2
1-3 23- 19- 26 22
29 316
0.08 2
1
than Type 309. Greater oxidation resistance than Type 310.
16- 10- 2.3 Mo Best corrosion 18 14 resistance in phosphoric, acetic and dilutes sulphuric acid, sulphurous and halogen salt water and against pitting corrosion. 30 316 L 0.03 2 1 16- 10- 2.3 Mo Extra low18 14 carbon, no danger of intergranular corrosion when used below 430°C. 31 317 0.08 2 1 18- 11- 3-4 Mo Increased 20 15 corrosion resistance than Type 316. 32 321 0.08 2 1 17- 9- Ti min Stabilized 18:8, 19 12 5 times virtually free C from intergranular attack in corrosive media up to 810 ° C 33 347 0.08. 2 1 17- 9- Cb-Ta Stabilized 18:8, 19 13 min 10 better than Type times C 321 34 348 0.08 2 1 17- 9- Cb min Stabilized 18:8. 19 13 10 times C; 0.1 Ta min D-Precipitation Hardening
35 17- 4 0.04 1 PH
1
17 4
2.75 Possess high Cu strength at temperatures up to 540°C.
36 17- 7 0.07 0.6 0.4 17 7 PH 37 PH15- 0.09 1 1 15 7 7Mc
1.15 AI 2.5 Used in aircraft Mo and missile 1.0 industries. AI 2.75 Mo 0.1 N 2.75 Mo 0.1 N
38 AM- 0.1 0.8 0.3 17 4 350
39 AM- 0.13 1 355
0.3 16 4
(5) Aluminium Alloys: Aluminium piping resists corrosion well by forming a protective aluminium oxide film. It is very resistant to sulphur compounds and most organics, including halogen organic compounds. Aluminium is highly ductile, but has relatively low strength. Its high strength-to-weight ratio results in the extensive use of aluminium alloys. Alloy 6063 is most widely used due to cost, good corrosion resistance, and mechanical properties. Alloys 3003 and 5052 are best used for extremely low temperatures. Alloy 5052 has the best corrosion resistance for slightly alkaline solutions. Aluminium should not, however, directly contact concrete because alkalis in the concrete will attack the aluminium. Aluminium has poor resistance to contaminants such as chloride. Aluminium piping is not compatible with most inorganic acids, bases, and salts beyond a pH range of approximately 4 to 9. In addition, nearly all dry acids, alcohols, and phenols near their boiling points can cause excessive aluminium corrosion. (6) Hastelloy: Hastelloy, a nickel-molybdenum-chromium alloy, offers excellent resistance to wet chlorine, hypochlorite bleach, ferric chloride, and nitric acid. Hastelloy, and related alloys, can be seamless or welded pipe. Seamless pipe is manufactured pursuant to ASTM B 622 and ASTM B 829, and welded pipe in pursuant to ASTM B 619 and ASTM B 775. The material class is specified as class 1 or 2. Class 1 pipe is welded and solution annealed, and class 2 is welded, cold-worked, and then solution annealed. Class 1 pipe may have sunken welds up to 15% of the wall thickness, while class 2 pipes do not have sunken welds. (7) Monel: Monel, a nickel-copper alloy, combines high strength with high ductility as well as excellent general corrosion resistance. It is specified particularly when seawater or high temperatures may accompany industrial chemicals. It must not be exposed to sulphur or molten metal’s when it is
hot. Monel is provided either seamless or welded. Seamless, cold-worked pipe is made in pursuant to ASTM B 165 and ASTM B 829. Welded Monel, intended for general corrosive service, is manufactured in accordance with ASTM B 725 and ASTM B 775, and is readily available in nominal pipe sizes 6 mm (1/8 in.) to 750 mm (30 in.), dimensioned as schedules 5S, 10S, and 40S. The pipe material conditioning, either annealed or stress relieved should be specified. (8) Inconel: Inconel, a nickel-chromium-iron alloy, is noted for having high temperature strength, while maintaining excellent corrosion resistance. Similar to all the nickel and nickel alloy piping systems, Inconel pipe can be provided either seamless or welded. Seamless Inconel pipe is available in nominal pipe sizes 8 mm (1/4 in.) to 150 mm (6 in.), dimensioned to schedule 5, 10, 40, or 80. It is manufactured pursuant to ASTM B 167 and ASTM B 829. The material conditioning should be specified; hot-worked, hot worked annealed or cold-worked annealed. The conditioning determines tensile strength; for example, the tensile strength of a 150 mm (6 in.) seamless Inconel pipe is 515 MPa (75,000 psi) for hot-worked and hot-worked annealed tempering and is 550 MPa (80,000 psi) for cold-worked annealed tempering. Welded Inconel pipe, intended for general corrosive and heat resisting applications, is produced in accordance with ASTM B 517 and ASTM B 775. Manufacturers will have to be contacted to confirm available sizes and schedules. (9) Cupronickel: Cupronickel (Copper Alloy) is very ductile and malleable metal and does not corrode easily in normal wet/dry environments. Being a noble metal, it does not normally displace hydrogen from a solution containing hydrogen ions. However, copper corrodes rapidly when exposed to oxidizing agents such as chlorine, ozone, hydrogen sulphide, nitric acid, and chromic acid. It is very susceptible to galvanic action, and this demands that padded pipe hangers are used and that attention is paid to contact with dissimilar metals. Seamless copper pipe is made pursuant to ASME B 42. Various alloys and tempers may be selected. The copper alloys vary based upon the oxygen and phosphorus contents, and temper is selected based on required tensile strength. It is available in nominal pipe sizes range from 6 mm (1/8 in.) to 300 mm (12 in.), in three wall thickness: light, regular, and extra strong. (10) Cobalt-base Alloys (Stellite): Cobalt–base alloys containing chromium, nickel, molybdenum and tungsten have excellent high temperature strength, corrosion resistance and red hardness. Typical alloys of this group are Stellite 21 (Vitallium), Stellite 31 (X-40). Super Alloys such as S-816 and 73 J are precipitation-hardening alloys and contain columbium and tantalum additions. (11) Lined Steel Pipe: Lined carbon steel pipe with a material able to withstand chemical attack are used to carry corrosive fluids. Full length of lined pipes with flanges, fittings, elbows, and tees etc, are available readily. Lining like rubber can be applied after fabricating the pipe, but pipe is often pre-lined. Lining of various rubbers, plastics, metals and vitreous material is available. Lining is made from Plastics like Polypropylene, Polyethylene, Poly-butylenes, Poly-vinyl chloride, Acryl nitride Butadiene Styrene, Poly-olefins, and Polyesters. Carbon Steel pipe coated with zinc, by immersion into molten zinc, i.e. hot-dip galvanized is used for conveying drinking water, instrument air and various other fluids. Rubber and Basalt lining is often used to handle abrasive fluids. (12) Plastic Pipes: Polymers are organic substances and is derived of carbon and hydrogen. They are
also known as plastic. They are light in weight and are soft as compared to metals. They possess high corrosion resistance and can be moulded in to various forms or shapes by the application of heat and pressure. These are used for transporting actively corrosive fluids, and are especially useful for handling corrosive or hazardous gases and dilute mineral acids. Plastics are used in three ways as all plastic pipe, as filled plastic materials (Glass fibre reinforced, carbon filled, etc.), and as lining or coating material. Plastic pipe is made from Polypropylene, Polyethylene, Poly butylenes, Poly vinyl chloride, Acryl nitride, Butadiene Styrene, Cellulose Acetate-butyrate, Polyolefin, and Polyesters. Pipe made from Polyester and Epoxy resins is frequently glass fibre reinforced (FRP) and commercial product of this type has good resistance to wear and chemical attack. (13) Ceramics: Ceramic is defined as calcinations of one of metal with a non-metallic element. Hence metal sulphide, metal carbides, metal nitrides, and metal borides, metal silicates are considered as ceramics. (14) Ceramics Alloys (Cremates): It has been found that ceramic materials such as pure Alumna, Beryllium, and Zirconium have better high temperature strength characteristics than metals at temperatures above 1000 0C. But they have poor thermal conductivity and shock resistance. The poor thermal conductivity of ceramics can be improved in newly developed materials called cremate. Cremates are combinations of refractory, metals and ceramics in a ductile matrix. (15) Refractory -base Alloys: Refractory alloys containing molybdenum, tungsten, chromium have good creep resistance at temperature above 800 0C. Their use is limited due to their excessive brittleness at room temperature. (16) Glass: Generally, Borosilicate glass is used for pipes and fittings. All glass piping is used for its chemical resistance, cleanliness and transparency. Glass pipe is not subject to crazing, often found in glass-lined pipes and vessels subjected to repeated thermal stresses. Pipes, fittings and hardware are available both for process piping and for drainage. Process lines of 25, 40, 50, 80, 100 and 150 mm NB are readily available, with 200 Deg C as the maximum operating temperature. The pressure range are up to 4 kg / sq. cm. for 25 to 80 mm NB, 3.5 kg / sq. cm. for 100 mm NB and 2.5 kg / sq. cm. for 150 mm NB.
2.2
Metallurgical Structure of Metals
The atom of metal in solid state is orderly arranged in space lattice structures. There are fourteen possible types of space lattice structures found in metals, but three space lattice structures are of primary useful which are available in piping materials. These are: BCC: Body centred cubic space lattice. FCC: Face centred cubic space lattice. HCP: Hexagonal close packed space lattice. Few metals like Iron, Titanium, Cobalt and Tin differ in all these space lattice structures. When these metals are heated at above specific temperature, they change from one type of lattice structure to another type of lattice structure. Similarly, they change their lattice structure when they are cooled below specific temperature. This behaviour is the main reason for the importance of heat treatment of the metals. By heat treatment many variety of the properties are achieved. Similarly, adding of the foreign “atoms” (Alloying elements) to a pure metal also has various effects. They occupy an interstitial position by locating themselves in between existing atom of the lattice. Sometimes they replace the atom of the pure metal in the lattice structure. Thus the minute percentage of any added elements produce major changes in the mechanical, physical and metallurgical properties of the metal. This is the main reason of alloying of any metal for piping. BCC space lattice contains two atoms per cell, FCC space lattice contains four atoms per cell and HCP space lattice contains two atoms per unit cell. Other atoms surround each atom of the crystal structure and all the atoms have identical surroundings. The number of nearest surrounding neighbours of any atom is called the “Coordination number”. More closely packed atoms in the lattice will have higher coordination number. This number varies with the type of the crystal structure as mentioned below: Table: Coordination numbers for different crystal structures S. No.
Crystal Structure
1. 2. 3.
BCC FCC HCP
Coordination Number 8 12 12
Micro Structure: The metal is composed of the atoms. The orderly arrangement of the atoms of a material in the solid state is called the structure of the material. The appearance of the structure of a material under microscope is called microstructure. Microstructure examination of material is done to reveal the structural defects or impurities of a large area. The method requires polishing and chemical etching of the surfaces to be examined. Equilibrium Diagram: The atoms of the same element or different elements combine to form crystals. The crystal can be of different phases such as solid phase, liquid phase or vapour phase, depending upon the pressure and temperature. A chart, a map or a diagram known as “Equilibrium Diagram” represents the existence of these different phases in an alloy system. It is also called phase diagram or
a constitution diagram. Thus an equilibrium diagram is a representation of the existence or changes of various phases in an alloy system, with changing temperature and composition. Pressure is assumed to be constant of one atmospheric value. There are many equilibrium diagram illustrated for different materials. But the most commonly used diagram is the "iron carbon" diagram which gives the heating and cooling rate and absorption temperature for heat treatment of alloy steel for piping. It also shows the presence of many phase and micro constituents such as ferrite, austenite, pearlite and ledebrite. At room temperature, the iron atoms are arranged in BCC (Body Centred Cubic) lattice and are called “alpha iron arrangement”. It is the purest form of iron containing only 0.006 % carbon. It is called “Ferrite”. It is magnetic, soft and ductile. It can go extensive cold working. When temperature reaches at 7270 C, pure iron transforms from BCC to FCC (Face Centred Cubic) lattice, which is known as “gamma iron”. It is called “austenite”. It is non-magnetic but it is also soft and ductile. The temperature at which alpha iron changes to gamma iron is known as the “Transformation” or “critical point” or “Critical temperature”. This is called lower critical temperature. The A3 (lower critical) temperature varies from 7270 C to 9120 C depending upon the carbon content. At temperature 13900 C, the FCC lattice structure changes back to BCC arrangement and called “Delta ferrite”. Such changes are called allotropic modification. The addition of carbon in the material lowers the A3 transformation temperature. Until the carbon content reaches to 0.85 %, when alpha iron (ferrite) transforms austenite, the iron carbides (F3C) go into the solution. It is a magnetic phase at room temperature. It is called cementite phase. It contains 6.67 % of carbon. It is extremely hard and brittle phase. It becomes paramagnetic at 2900 C. This transformation is called A1 transformation. This transformation is reversible. However, there is a log in attaining the equilibrium condition transformation temperature while heating and cooling. On heating the transformation starts at AC1 and is completed at AC3point. While on cooling the transformation starts at Ar3 critical point and is completed at Ar1 point. When austenite phase is cooled slowly below 7270 C pearlite phase is obtained. It is a mixture of ferrite and cementite. Pearlite contains 88.5% ferrite and 11.5 % cementite. Pearlite has a variable hardness from 20 Rc to 30 Rc. When liquid alloy containing 4.3 % carbon is cooled below 11480 C, ledebarite is obtained. There are three important phase transformation temperatures. A1, Ae1, A3 & Ae3 mean equilibrium temperature. AC1, AC3 & Aecm means heating and rising temperature. Ar1 & Ar3 means cooling (decreasing) temperature. Increasing in carbon content of alloy increases the amount of pearlite present. When we see with microscope, the pearlite looks black, ferrite looks white and cementite looks white too when etched with Nitric Acid. However, the presence of cementite can be identified by a special etching technique, which etches cementite black and pearlite white. In pipe fabrication, hot forming on piping shall be done between A1 & A3 point. Normalizing must be done above the AC3 temperatures. Stress relieving or tempering shall be done below the AC1 temperature. Non-Equilibrium Phase Transformation: An equilibrium diagram shows various phase of transformation, which takes place in an alloy system under equilibrium condition of heating and cooling. But when an alloy is either heated or cooled at faster rates, some other phase of transformations occur which is not shown in equilibrium diagram. This is true for iron carbon alloys,
when high temperature phase of iron carbon alloys i.e. austenite, is cooled rapidly or transformed thermally at some intermediate temperature, it result in the formation of new phases, called “Martensite” or “Bainite” respectively. These phases will have better mechanical properties than equilibrium phases of iron carbon alloys. Transition Temperature: The temperature range, which influences the transition phase of steel, is known as Transition Temperature. These are elaborated below: a) Effect of composition on transition Temperature: Carbon and nitrogen are considered the most important elements, which raise the Transition Temperature of the steels. Oxygen and phosphorus in quantity greater than tolerable and silicon quantity greater than required for oxidation also raise the Transition Temperature of the steels. Generally, most conditions made to steel raise the transition temperature. Nickel in general and under certain condition manganese lower the transition temperature. b) Effect of workmanship & procedure for fabrication on transition Temperature: By limiting the extent of surface defect of under out, porosity and by controlling welding i.e., by faster rate of electrode travel reached the width of heat affected zone, the transition temperature can be reduced. Transition temperature tends to rise, as the heat-affected zone becomes wide. Similarly preheat and inter pass temperature during welding also effect transition temperature. c) Effect of Grain size on transition Temperature: The transition temperature will be lower if the ferrite grain size is smaller. And if the steel is rolled at low final rolling temperature, solely as if cold rolled, and cooled at high rate of cooling the ferrite grain size will be smaller and so the transition temper will be low. Aluminium and Silicon addition during final deoxidisation also provide fine (small) grain. d) Effect of straining on Transition Temperature: Cold deformation and straining generally raises the transition temperature of steel. e) Effect of Creep to Piping Design: The allowable stress value to use for a given material at a given temperature is given by the ASME Boiler and Pressure Vessel Code under which the piping is to be built. The subcommittee on Stress Allowance for ferrous materials of the ASME-BPV Code Committee establishes the values for designed stresses for steels. This subcommittee collects all variable data and establishes tables of maximum allowable design stress value. At temperatures below the creep range, allowable stress values are established at the lowest value of stress obtained from, using 25 per cent of the specified minimum ultimate strength at room temperature, or 25 per cent of the minimum expected ultimate strength at temperature, or 62½ per cent of the minimum expected yield strength for 0.2 per cent offset, at temperature. For bolting material, the stress values are based on 20 per cent of the minimum tensile strength, or 25 per cent of the yield strength for 0.2 per cent offset, whichever is lower? It is recognized that bolts are always expected to function at stresses above the design value as distinguished from other parts. TABLE: MINIMUM IMPACT- TESTING TEMPERATURES
FOR
VARIOUS LOW- TEMPERATURE STEELS
Material
Grade
Carbon steel 3½ Ni-steel Cr-Cu-Nisteel 4 ½ Ni steel
1 3 4
Temperature F. -50 -150 -150
5
-150
min.
Low-temperature Limitations from Various Piping Materials: Low Temperature Suitable Material and ASTM Limit designation Zero Mild steel (A53, A120, A135) -29 C Mild steel (A53, A 135) -45 C Killed steel (A333, Gr-1) -101 C 3 ½ % Ni-steel (A333, GR-3) -198 C Austenitic stainless steel (A312 Gr TP 304, 316 etc.) No limit Nonferrous copper, brass, aluminium Low temperature limitations for various piping materials are given in above table. Low alloy steel (A333 Gr 1&3) shall be used at temperature below -20 C. They should have at least 15 ft. lb. impact value in V-Charpy impact test. Austenitic stainless steel (A312 Gr 304 & 316 etc.) shall be used for low temperature provided as shown in the above table.
2.3
Mechanical Properties
The mechanical properties generally tend to change with the change in metallurgical characteristics. Thus to obtain desired mechanical properties in metal, sometimes metallurgical characteristics is to be changed by changing the microstructures by accomplishing operations like heat treatment, hot working, cold reduction or expansion. Mechanical properties are very important in selecting the materials for any purpose. However other physical properties such as workability, weld ability, toughness, modulus of elasticity, creep strength, coefficient of expansion, hot shortness and others have an important bearing on selection of piping materials. The mechanical properties of the materials are hardness, tensile strength; yield strength and elongation, wear toughness, resilience, young’s modules, brittleness, fatigue strength, modulus of elasticity and creep strength in general. Table: Mechanical Properties of Various Materials Material
Ingot-iron
Composition
Malleable Iron
Elongation % 40-60
140-160
40-50
35
0.5 C
190-210
65-75
20
0.5 C
-
170
3
0.8 C
240
90-93
10
1.1 C
-
180
1
350-550
-
-
150-320
15.40
<1
170-300
38-80
2-17
140-285
28.70
3-14
-50-90 -140-200
-17-30 -3-15
99.9 Fe Steel 0.2 C
Mild (Normalized) Medium Carbon Steel (Normalized) Medium Carbon Steel (Hardened) Eutectoid Steel (Normalized) Hyper Eutectoid Steel (Hardened) White Cast Iron (0.41.0 Si) Gray Cast Iron. Modular Iron
Mechanical properties Hardness UTS (BHN) (kg / cm2) 60-100 20-25
2.5-3.5 C, 0.5-4.0 C, 1.0-3.0 Si, Cast - 4.1 C, 1.0 - 2.8Si, < 0.1 Mg. Cast 2.0 - 3.0 C, 0.9 - 1.65 Si
Martensitic S.S. Annealed Harden & Tampered
-0.15-1.1C, 1- 150-260 1.2Mn, -0.5-1.0Si, 12- 390-580
18Cr -(AISI 403, 180-260 410,414, 416,420,440) Ferritic (Annealed) 0.08-0.2C, 1- 150-170 A 501, 401, 430, 405, 1.5Mn 5-17Cr 442 & 446. Austenitic S. S. (Annealed) A 304, 0.15-0.8C, 2- 140-180 316, 321 & 347. 10Mn, -(Cold Worked) A 201, 1-3Si, 14- 200-400 202, 301, 26Cr, 8Ni Nickel 97-99% -Monel 65 Ni, 35Cu -Constantan 40-60 Ni, 40- -60 Cu Hastelloy (5- 50-85Ni, 15- -25Fe) 35Mo Inconel 40-50Ni, 20- -30Co, 1530Cr (a)Cupronickel 70Cu, 30Ni -(b)Germen Silver 65Cu, 23Zn, 12Ni Yellow Brass 65Cu, 35Zn -Red Brass 85Cu, 15Zn -Naval Brasse 60Cu, 25- -29Zn, 0.75Sn Bronze/Gun Metal 88-95Cu, 5- -10Sn, 0-0.2P Aluminium Bronze 86Cu, 0.5Al, -3.5F Beryllium 98Cu, 1.7Be, -Bronze 0.3Co Nimonic 70-75Ni, 15- -20Cr, 2-3Ti Titanium 99Ti -Magnesium 90-95Mn, 1- -Alloy 3Zn Aluminium Alloy 90-98Al, 1- -64.5Cu, 1-5 Mg, 0.50.6 Si up to 300 0 C up to 700 0 C
-65-90
-20-30
55-60
20-30
55-80 -80-130
40-60 -4-25
30-40 55-130 45-70
20-40 10-30 5-35
--
--
100-150
20-40
35 40
50 42
32-37 27-31 38
55-65 42-48 47
28-46
30-64
70
12
120
5
100-130
20-40
60-80 25-35
25 5-20
30-50
20-30
2.4 Mechanical
Factors affecting
Properties (i) Heat Treatment: Heat treatment is important mainly because of the effect on the structure of the metal. By increasing the grain size larger by heat treatment techniques, the creep and stress-to-rupture properties of steel are improved at elevated temperature. Hence, normalized and tempered steel is often better and superior in quality than to the normal steel in fully annealed condition at elevated temperature of service. But some commercial heat-treating producers do not provide and control the uniform temperature, cooling rate etc. and hence do not give the better grain structure in steel. Stainless Steel grade TP 304 exhibits good resistance to atmospheric corrosion and oxidation. Type SS 309 & SS 310 exhibit greater resistance to oxidation because of their higher chromium & Nickel content. SS 310 is specially preferred in the case of a service where intermittent heating and cooling are faced by the material. (ii) Notches: The sudden brittle failure is generally ascribed to notch sensitivity of steel at the operating temperatures to which it was exposed. They may consist of minute surface of subsurface cracks, surface laps or scabs, visible scratches, abrupt shape changes such as sharp corners, tool marks, grooves from drawing dies, edges, etc., or fabrication defects, such as from arc strikes or similar causes. The condition is accentuated as the thickness of the steel increases. Notches also are stress raisers. The greater the sharpness of the notch, the greater will be the degree of restraint, the more severe will be the stresses as to both, tri-axially and magnitude and the higher will be the transition temperature. The fact of notches of varying severity on the brittle behaviour is tested with Charpy test specimens. In other words, steel, which contains extremely severe notches, will fail in a brittle manner at higher ambient temperatures than if less severe notches were present. (iii) Dissimilar metals: When dissimilar metals are welded together, the significant metallurgical effect takes place known as (1) Dilution of weld metal and (2) Diffusion across the dissimilar metals joint as a result of heat treatment or of high temperature service condition at a temperature exceeding 8000 F. Dilution is the mixing of molten filler metal with base metals. The amount of dilution varies with the different welding process & welding conditions. The undesirable effect of this dilution may be minimized by careful selection of electrode, preheat and post heat treatment. Diffusion is the process of movement or migration of atoms of dissimilar metals at the joint across the bond. In steels of dissimilar metals, the carbon atoms migrate across the bond. This is called carbon migration and depends on time and temperature. Below 8000 F, the carbon migration is not effective over after a long service. But above 8500 F, the carbon migration is effective after 5 to 10 years. The Embrittlement may become significant at 5500 F in one year. It would be very effective to produce some degree of Embrittlement at 12000 F. The time factor may be reduced to days. So in general, the use of carbon steels is limited to service below 7500 F and use of carbon molybdenum steels is
limited to service below 8000 F. The carbon migration depends on the degree of dissimilarity i.e., increases with the increase of alloying element percentage. More precisely the carbon atoms migrate towards the steel containing the stronger carbide forming elements or the greater quantity of them.
2.5 Temperature Affecting Mechanical Properties (i) Low Temperature: Steel is generally considered to be a ductile material. When it is overloaded, it usually gives warning by bulging, stretching, bending, or necking before rupturing. However, steels sometimes rupture without prior evidence of distress. This is due to brittleness of steel at low temperature. Brittle failure is accompanied by little plastic information and the energy required to propagate the fracture is quite low. Under such conditions, steel shatters like glass. This extreme behaviour generally occurs only at low temperatures. The three conditions, which propagate this tendency for steel to behave in a brittle fashion, are; 1) High stress concentrations i.e. notches, nicks, scratches, internal flaws or sharp changes in geometry. 2) High rate of straining. 3) Low temperature. The transition temperature for any steel is the temperature above, which the steel behaves in a ductile manner and below which it behaves in a brittle manner. Steel with a high transition temperature is more likely to behave in a brittle manner during fabrication or in service. It follows that steel with a low transition temperature is more likely to behave in a ductile manner and therefore, steels with low transition temperatures are generally preferred for service involving severe stress concentrations, impact loading and low temperatures or combinations of the three. Metallurgical factors, such as deoxidisation, chemical composition, rolling, forging or extruding and heat treatment influence the transition temperature of steel. In carbon-steel piping materials, under the worst conditions, the transition temperature may be above 93 C or, under the best conditions, below minus 93 C Steels treated in accordance with most favourable deoxidisation practice are those which are fully killed. In pipe steels deoxidisation is generally accomplished with sufficient silicon to provide about 0.10 to 0.20 percent of silicon in the steel. Carbon influences unfavourably the transition temperature. The upper limit in plain carbon steels is accepted as about 0.25 percent and in low alloy steels as about 0.20 percent or even lower. Nickel lowers appreciably the transition temperature of carbon steel. Austenitic chromium-nickel stainless steel and some high-nickel steel show no transition at temperatures lower than minus 163 C. Steels, which have been fully annealed, are in the poorest condition to resist Embrittlement. Normalizing offers improvement. Frequently further benefit is derived from tempering or stress relieving after welding. The conventional static tensile and bend test do not differentiate between steels of varying susceptibilities to brittle behaviour. This is because they measure the mechanical properties of steel under the particular conditions and not its behaviour in an actual structure as influenced by many factors as design, workmanship, surface notches, and welding quality and stress distribution. The determination of the temperature at which steel becomes susceptible to brittle failure under certain conditions is based on the three testing categories, such as, Impact energy; Notch ductility and Fracture appearance Under this test, the transition temperature is obtained. These are the only value which assures the steel which shows the low transition temperature is less likely to behave in a brittle manner that the steel showing high transition temperature.
(ii) High Temperature: a) Tensile Strength: While selecting piping materials for higher temperature service, mechanical & physical properties of material must be considered. The important mechanical properties are tensile strength, proportional limit, thermal fatigue (shock resistance), mechanical fatigue, tortional elastic limit, toughness etc. The tensile strength of some pipe materials tends to increase with respect to corresponding value at ambient temperature for a few hundred degrees. After further rise in temperature, tensile strength falls of rapidly. Many materials show a continuous decrease in strength with increase in temperature. b) Ductility: Ductility of material is also of great importance. For 5 diameters hot bending radius, the piping materials should exhibit a ductility of at least 20% over a temperature range of which hot bending is done. For the extrusion of outlets or swaging of reducing ends, a ductility of 25 to 30% is desirable at the forming temperature. Less ductility leads to failure of the piping product during hot forming. c) Creep Strength: The heat treatment generally improves the creep and stress-to-rupture properties of steels and alloy steels at more elevated temperatures. d) Composition: Composition of the material is the most important variable, which affects the high temperature strength of the materials. But all elements do not help in getting higher strength. Similarly, certain quantity of the alloying element helps in getting good strength. The correctness of element and its quantity is highly important because the excessive temperature may affect the grain growth causing coarsening. The cold or hot working on the material tends to break up the original grains and produce refinement, particularly, under effect of high temperature.
2.6 Features
Factors affecting Service
Piping in operation fails by cracking, corrosion or sometimes by combination of the two due to the following reasons: a) Non-Flexibility: While designing, provision of insufficient flexibility leads to cracking failure of steam line or any hotline. While in shut down, if gets cooled and contract and during operation it gets heated up and expands. This thermal contraction and expansion in the line lead to service failure if sufficient flexibility in all direction is not provided. b) Notches: When heavy wall with higher thickness is designed and welded with a pipe of light wall thickness, a sharp corner or sudden change in section occurs in the line. Also in socket weld design a sudden change in section occurs in the line. In case of design of reinforcement pads or rings where the weld does not blend gradually into the piping wall, a sudden change in section occurs. The sudden change in sections or thickness work as a notch at that location and cracking take place due to thermal or mechanical figure. c) Weld Defect: The location of shop weld joint and field weld joints with respect to accessibility for NDT inspection to find out the defects and space to attend the repair, if any. If the defects exist, it affects service features. Sometimes the wrong design of type of weld such as butt weld with groove angle or socket weld or slip-on weld joint is also the cause of system failure by crack. d) Material: The selection of material based on their use with upper temperature, lower temperature and transition temperature is also reason for cracking in the heat-affected zone near the weld due to graphitization. e) Weld Metals:Improper selection of the weld filter metal or electrode, specially, when temperature exceeds 800 F, has caused the crack across the interface zone of the weld metal and base metal. f) Base-Metal Defects: Mechanical defects such as laminations. Laps, scabs & tears, if it is perpendicular to the pipe surface or diagonal to the pipe surface, acts as a very critical notches and cause cracking failure near the weld joints. g) Hardness (Metallurgical notches): The hardness of steel varies with its chemical composition variation & heat treatment of the steel. When the difference in hardness value exceeds 70 to 100 points Brinnel in thermal & mechanical fatigue condition then the junction point or line between two different hardness materials behave like a notch and a crack takes place. This is known as metallurgical notches. For example: Area Brinnel hardness value Base metal 180 Heat affected Zone 232 Heat affected zone near the 280 weld Weld deposit 179
i) Carbonization during Hot Forming: Hot forming into plate, pipe and fitting, during manufacturing, by conventional method, is done by heating by means of gas burner to a temperature of 1500 to 1850 F with commercial gas (not a natural gas). Then the steel surface, most likely, gets carbonized. This carbonized surface, after welding, fails in service due to severe stresses caused due to pipe movement. Such type of failure takes place in service after fabrication and all blame goes to the fabricator & inspector but not to the manufacturer who has carbonized the pipe or elbow surface while making elbow by gas heating. However, such carbonization can be detected only by weld ability test, particularly by bend test because it will develop crack in the parent metal. It can be detected by photomicrographs of the surface. It is very costly affair. j) Incorrect Material: Generally, painting technique is applied during storing the different material in fabrication shop. But in long time, the paint goes away and it is very difficult to identify carbon steel & alloy steel piping components. Vary often, by mistake, Alloy Steel pipe is welded with carbon steel pipe or fittings or vice versa. Hence it becomes a case of metallurgical notch and fail in service in severe condition of thermal mechanical fatigue. A number of service failures take place in steam power plant due to material identification mistake before welding together. k) Fabrication Mistake: Fabrication mistake such as deep cut during gas cutting or machining for end preparation and fit up, or welding defects at root pass such as lack of penetration, slag inclusion etc. work as a notch and hence joint fails in service during severe thermal & mechanical fatigue condition. That is the reason; the root pass is done always by inert gas tungsten arc welding in a high temperature high pressure piping system. l) Heat Treatment: Some carbon-steel pipe is furnished in the hot finished condition. Hot finishing is generally performed between 1600 and 2200 F and is followed by air-cooling. Under these conditions these steels can be compared to normalized steels, although it should be recognized that the temperature of finishing is an important factor. When piping materials are cold worked, their strength and hardness are increased and ductility is decreased. That is why cold expansion while bending of pipe or cold working is done intentionally to obtain the higher strength value in A106 or some API grade material. However, the effects of cold work can be removed by heat treatment. m) Multi-axial stress: Multi-axial tensile stresses raise the transition temperature. This is particularly true at the base of a notch or crack where multi-axial tensile stresses of considerable magnitude may develop. n) Section Size: If the section size is increased without other changes in geometry, the transition temperature will also be increased. o) Design: Design based upon conventional tensile-test data gives no assurance that piping will not fail in a brittle manner. Nor can such assurance be obtained by simply increasing the section size with the intent of increasing the factor of safety. In the presence of notches, increase in section size will most likely increase restraint and may even lead to failure at lower applied loads.’
Table: Limitation of temperature & pressure on Materials
Material
Max. Pressure Application & temperature Cast grey 250 psi, 2500 F Pipe, valves & Irons 250 psi, 4500 F fitting (A 278) -DOMalleable Cast 300 psi, 500 F Pipe, valves & Irons fitting Carbon steels 775 F Pipe, valves & fitting 1 ¼ Cr-½ Mo 950 to Boiler piping & steam steels 1000 F piping. ¼ 1060
F
Steam & power plant piping
1500 1500 1500
F F F
Refinery Piping Refinery Piping Refinery Piping
Cr-1 Mo steels 5Cr-½ Mo Steel 7Cr-½ Mo Steel 9Cr-1 Mo Steel
2.7
Elements affecting Alloy Steel
There are four most important elements, which are added to piping steel materials such as Carbon, Chromium, Nickel, and Manganese. Other commonly added elements are Silicon, Molybdenum, Tungsten, Vanadium, Copper, Boron, and Aluminium. The main constituents of plain carbon steel are iron and carbon. The properties of carbon steels are directly related to the percentage of carbon present. In addition to carbon, plain carbon steels also contain other elements such as Manganese, Silicon, Sulphur, and Phosphorus in amount shown below: S. NO. 1 2 3 4 5 6
Elements Carbon Manganese Silicon Sulphur Phosphorus Iron
By weight 0.04 TO 1.20 % 0.30 TO 7.00 % 0 TO 0.30 % 0.04 Max % 0.04 Max % Balance %
Alloying elements: Any alloying element, when added to steel, performs different effect depending upon their characteristic and amount. Some alloying element effects are described below: Carbon: Carbon is responsible for the required hardness and strength in the steel. Accordingly this grade of material gives good and desirable response to heat treatment and more tensile strength at elevated temperature and hence mostly used in steam services. Chromium: Chromium is one of the important alloying elements being added to piping material to enhance the inbuilt properties of the material such as alloy steel or stainless steels. The combination of iron and chromium form a continuous series of solid solutions. A small amount of chromium lowers Ac3 point of steel where as larger percentage of chromium raises Ac3point. It also lowers the austenite to Delta-ferrite transformation temperature. When an alloy containing 11 to 12 % of chromium is heated, the ferrite begins to transform to austenite at about 815 C. This continues with increasing temperature till alloy is fully austenite. On the other hand, the alloy with 18 percent of chromium is not subject to these phase transformations and hence remains in its ferrite structure. Hence the alloy with 18 percent chromium cannot be hardened when quenched from elevated temperature. Chromium also increases the desired properties of steels or has the following effects, such as, Increases harden ability; It forms carbides having high hardness and wear resistance; It provides strength, wear and oxidation resistance at elevated temperatures; It provides corrosion resistance if added in higher amount and it provides heat resistance to alloy. This characteristic of Iron-Chromium alloy has resulted in two types of major groups of stainless steels, such as, a) Martensite stainless steel; b) Ferrite stainless steel. Nickel: Nickel is the second important alloying elements being added to piping material to enhance the inbuilt properties of the material such as alloy steel or stainless steels. The combination of iron and nickel form a continuous series of austenite range. The addition of Nickel to alloy steel (0.1 percent carbon with 18 percent chromium) progressively extends the austenite range until the alloy becomes completely austenitic even at room temperature. This property of Nickel has resulted in the development of very important group of austenitic stainless steel. It has the following property when added in alloy.
Nickel dissolves in Ferrite and increases hardness, strength, and toughness without sacrificing the ductility. It is added up to 5% for the parts subjected to high static and impact stresses in service, such as, It increases harden ability of steel; It increases impact resistance of steel at very low temperature. Hence it is added to a low temperature steel pipe service. Higher amount of Nickel (8 percent or more) is added to increase corrosion resistance of high Chromium steels. Nickel steels are used in large engineering structures such as armour plates, highly stressed bridge members, shafts etc. Nickel gives higher mechanical properties after annealing and normalizing. Therefore these steels are used for large forging & castings, which cannot be reacting, while quenched. Manganese: Manganese is present to provide a minimum harden ability and strength after working. Manganese tends to shift the curve to the left in carbon steel. It also has the properties, such as, it dissolves in ferrite and increases hardness and strength; it increases harden ability to a great extent; it takes care of Sulphur present in the steel by forming manganese-sulphide if it is added in the quantity 3 to 8 times that of sulphur in the steel; it is added to free cutting steels up to a maximum limit of 1.6 percent; and it is added about 12 to 14 percent in steel to produce an extremely tough, wear resistant. Manganese is one of the least expensive alloying elements and is always present in steels. Molybdenum: Molybdenum acts as a ferrite stabilizer. It tends to shift the curve to the right along which the chromium Nickel alloy steel becomes fully austenitic. It also has the properties, such as, it increases the harden ability to a greater extent; it forms carbides having high red hardness and wear resistant; it enhances the effects of other alloying elements such as chromium, Nickel & Manganese when added 0.15 to 0.30 percent of molybdenum to steel; it eliminates the temper brittleness in steel; it resists softening of steel during tempering and heating; it acts as a grain growth inhibitor when steel is heated to high temperature and it is an expensive alloying element and plays a great importance in high-speed steels. It is also added to carbonizing steels and heat resisting steels. Silicon: Silicon acts as stabilizer in ferrite steel. It tends to shift the curve to right along which the Chromium Nickel alloy steel becomes fully austenitic. Silicon is present only when steel is dioxide. It has some more properties, which are described here. Silicon dissolves in ferrite increasing strength and hardness without lowering the ductility. It is added as a deoxidizer during casting of ingots. It forms SiO2 with Oxygen present in steels with a quantity of silicon between 0.1 to 0.3 percent. Silicon between 0.3 to 0.5 percent is added for soundness of castings. It increases the permeability of steels and reduces iron losses in electrical use. Hence it is added up to 5 percent in magnetic materials to be used in electrical such as transformers, motors, and generators. Silicon is present in almost all steels; it is important alloying element for transformer, motor and generator steels and generator steels and also springs steels, chiselled steels & punch steels to increase their toughness. Vanadium: Vanadium inhibits grain growth when steel is heated at high temperatures. It increases the harden ability of steels. Vanadium is strong carbide former. Vanadium carbides possess highest hardness and wear resistance. Vanadium improves fatigue resistance and generally used in tool steels & carburizing steels. Tungsten: Tungsten performs similar function as molybdenum but it is an expensive alloying element. Generally it is not used for alloying. Sulphur: Sulphur phosphorus is present as unwanted impurities. Sulphur is always present in steel as inclusions of iron sulphide (FeS) and as manganese sulphide (MnS. In piping material, sulphur is undesirable element and hence it is removed by open hearth and electric furnace method of steel production. Maximum sulphur presence is limited up to 0.04 percent is pipe material. Sulphur is added up to 0.33 percent as on alloying element in certain free cutting steels to increase the machine ability. Sulphur content in steel is undesirable because it has a strong tendency to form films and fine
particles at the grain boundaries. Iron sulphide (FeS) inclusion softens the steels and may melt at lower temperature. Sometimes it melts at lower temperature. Sometimes it causes disintegration by cracking in the rods or under the hammer. It is called ‘hot shortness’ or ‘Hot Embrittlement’. Phosphorus: Like sulphur, phosphorus is also always present in steels as an inclusion. It is desirable alloying element and its amount is controlled maximum up to 0.05% by open hearth or Electric furnace method. Phosphorus dissolves in ferrite increasing strength hardness and improving the resistance to corrosion. It is added to improve the machine ability to certain grade of free cutting steels to 0.12 percent. On the other hand it is an undesirable element because it has tendency to segregate in steels and is responsible for brittleness in steels, which is called ‘‘Cold-Shortness‘’. Cold-shortness is the reduction in impact strength at low temperature. Titanium: Titanium is strongest carbide former. Titanium is used to fix carbon in stainless steels and thus prevents the precipitation of chromium carbides. Copper: Copper increases atmospheric corrosion hardening resistance when added to steels between 0.01 to 0.4 percent. 0.6 percent copper is used for precipitation. Aluminium: Aluminium is added to the steels between 0.01 to 0.06 percent during solid fabrication of castings to get Fine grained steels. 1 to 3 percent of aluminium is found in nitriding steels to form aluminium nitride. Boron: It increases harden ability to the great extent even it is added between 0.001 to 0.005 percent. It is used as inoculators to obtain fine grain size. Boron is added to the surface of steel during case hardening treatment called ‘‘boriding’’ Lead: Lead is not desirable alloying element for steel. But sometime it is added maximum up to 0.35 percent to improve machine ability of steels. It is the cheapest element. However, the important functions of all the above alloying elements are summarized here below in table.
Table: Summarized Functions of Alloying Elements in Steel Sl. No 1
Alloying Element Sulphur
Typical Range <0.33
2
Phosphorus
<0.12
3 4
Lead Silicon
<0.35 0.2-2.5
5
Manganese
0.2-2.0
6
Nickel
0.3-5.0
Principal Function Improves machine ability. Reduces weld ability and ductility Improves machine ability. Reduces impact strength at low temperature Improves machine ability Removes oxygen in steel making. Improves toughness. Increases hardness ability Increases harden ability. Combines with sulphur to reduce its adverse effects. Increases harden ability. Improves toughness.
7
Chromium
0.3-4.0
8
Molybdenum 0.1-0.5 or Tungsten
9
Vanadium
0.1-0.3
10
Aluminium
<2.0
11
Copper
0.2-0.5
12
Boron
0.005
13
Titanium
1.0
Increases impact strength at low temperature. Promotes an austenite structure. Increases Resistance to corrosion and oxidation. Increases harden ability. Combines with carbon to form hard and wear resistance carbides. Increases high temperature strength. Inhibits grain grow that high temperature. Increases harden ability. Forms carbides having high red hardness and wear resistance. Enhances the effects of other alloying elements. Eliminate temper brittleness in steels. Increases high temperature strength. Inhibits grain growth at high temperature. Increases harden ability. Forms carbides having high red hardness and wear resistance. Improves fatigue resistance. Forms nitride in nitriding steels. Produces fine grain size in casting. Removes oxygen in steel melting. Improves atmospheric corrosion resistance. Increases harden ability. Produces fine grain size. Strongest carbide former. Added to stainless steels to prevent precipitation of chromium carbide.
Effects on Alloy Steel: Alloy steel is defined as carbon steel to which one or more elements as described above are added to get some beneficial effects as required by piping specifications. Due to
presence of alloying elements, the alloy steels are best piping materials to be used at higher temperature as well as at lower temperature. Alloying elements can affect the carbon steel constituent, characteristics, & behaviour in many ways. Some of the major effects of alloying elements are 1) strengthening of ferrite 2) formation of special carbides and compounds 3) shifting of critical temperatures and compositions and 4) lowering of the critical cooling rate. Their effects are described in detail below: Strengthening of Ferrite: The alloying elements are soluble in ferrite to a certain extent. When it is dissolved in Ferrite, it increases hardness and strength due to formation of solid solution. Silicon, Manganese and Nickel have a greater influence on harness and strength. Formation of Carbides: The alloying elements combine with carbon in steel and result in the formation of alloy carbides. These alloy carbides are hard and brittle. It provides resistance to softening at elevated temperatures. Chromium and vanadium carbides have maximum hardness and wear resistance. Shifting of critical temperatures and compositions: The alloying elements sometimes lower or raise the transformation temperatures of steel. Nickel and Manganese lower the temperature of austenite formation, while other elements raise the austenite formation temperature. Also, most of the alloying elements shift the eutectoids composition to lower carbon values. Lowering of critical cooling Rate: Most of the alloying elements shift the Isothermal Transformation Temperature (ITT) curve to the right hand side and hence result in decreasing the critical cooling rate required for the formation of complete marten site. This is a very useful effect and increases the harden ability of alloy steels. These elements are Mn; Cr; Ni & Molybdenum. Understanding the characteristics of these alloying elements phase relation is very important in forming and working of the piping materials. The presence of some ferrite in the microstructure increases significantly the tensile and yields strength of the material. However the material with over 10 percent Ferrite may develop crack when it is severely hot worked e.g. hot extrusion of outlets, in capping or in swaging operation. A fully austenitic material, the structure is more susceptible to cracking. This is true with stainless steel grade A 347 and A 348 type.
2.8
Selection of Piping Materials
The materials that are used for manufacturing pipes include: Carbon Steel (CS); Alloy Steel, Low Temperature Service Carbon Steel (LTCS); Stainless Steel (SS); Non Ferrous Metals like Inconel, Incoloy, Cupro-nickel and Non Metallic like GRE, PVC, HDPE, and Tempered Glass. The remaining materials are evaluated for advantages and disadvantages such as material costs, fabrication and installation costs; support system complexity; compatibility to handle thermal cycling; and cathode protection requirements. The highest ranked material of construction is then selected accordingly. The design proceeds with pipe sizing, pressure integrity calculations, and stress analyses. If the selected piping material does not meet those requirements, then the second ranked material is not used. Most failures of process piping systems occur at or within interconnect points, i.e. weld joint, flanges, valves, fittings. It is, therefore, vital to select interconnecting piping, equipment and other materials that are compatible with each other and the expected environment. Each material has its inherent properties and its use in pressure piping is subject to the qualification of (i) requirements, (ii) limitations and (iii) working conditions. Pipes and piping components are used in various plants such as power plant, refinery, petrochemicals, chemical plant, paper mills, gas transmission and nuclear plant to handle various fluids of different toxic nature. Pipes and piping component’s material varies accordingly. Basically carbon steel, alloy steel, stainless steel, aluminium alloy, cupro-nickel, nickel alloys, Monel, Hastelloy, tantalum, N – resist, HDPE, FEP or lined pipes and piping components are used in piping work of above plants. Table: Material’s Working Limit of Temperature Ranges Material Carbon Steel Low Temperature Steel (LTCS) Alloy Steel 304 Stainless Steel 316 Stainless Steel 321 Stainless Steel 347 Stainless Steel Aluminium Nickel 200 Inconel 600 Inconel 625 Monel 400 Incoloy 800 Incoloy 825
Acceptable Temperature Range -290 to 4260C Carbon -800C to 800C -290C to 5370C -2500C to 5370C -290C to 5370C -290C to 5370C -2500C to 5370C -1980C to 2040C -1560C to 3150C -1560C to 6490C -1560C to 6490C -1560C to 8150C -1560C to 8150C -1560C to 5370C
(i) Requirements: The possibility of the exposure of the piping to fire, melting point, degradation temperature, loss of strength at elevated temperature and combustibility of the piping materials under such exposure. The susceptibility to brittle failure or failure from thermal sock when exposed to fire or the fire fighting measures and possible hazards from fragmentation of materials in the event of failure. The ability of thermal insulation to protect piping against failure under fire exposure, such as, its stability, fire resistance and ability to remain in place during a fire. The susceptibility of piping material to receive corrosion under backing ring, in threaded joints, in socket-welded joints and in other stagnant and confined area. The possibility of adverse electrolytic effects of the metal is subject to contact with dissimilar metal. The compatibility of lubricants or sealant, which is used on threads with the fluid service. The compatibility of packing seals and B-rings, which is used with the fluid service. The compatibility of materials such as cement, solvents, solders, brazing materials, with the fluid service. The Chilling effect of sudden loss of pressure on highly volatile fluids, such as a factor in determining the lowest expected service temperature. The possibility of pipe support failure resulting from exposure to low temperature, which may embrittle the supports or high temperature, which may weaken them. The compatibility of materials, including sealant, gaskets, lubricants, and insulation used in strong oxidizer fluid of service (e.g. Oxygen or Fluorine). The primarily important consideration is the ability of the materials to withstand the continuous load acting in service of the piping for a long periods or long duration without failure such as distortion or undue plastic flow. The excellent mechanical properties at higher temperature of the materials are not only the selection criteria of the material, but the scaling and the oxidation are also the factors deciding the selection of piping the materials. The ductility is also the important factor in selection of the materials. This is the important requirement of the piping material to have the ductility minimum 20% to a temperature of hot bending for hot bending of the component to a radius of 5 times the diameter and a ductility of 30% at the temperature of hot working or the extrusion of outlets or the swaging of reducing ends. (ii) Limitations: The lack of ductility and their sensitivity to thermal and mechanical sock (such as cast iron malleable iron, high silicon, (14.5 %), is taken into consideration. In addition, the followings are also considered: The possibility of embrittlement where handling alkaline or strong caustic fluids. Possibility of conversion of carbides to graphite during long time exposure to temperatures above 427 C (800 f) of carbon steels, plain nickel steel, carbon manganese steel, manganese vanadium steel and carbon silicon steel. The possible conversion of carbides to graphite during long time exposure to
temperature above 468 C (875 F) of carbon-molybdenum steel, manganese- MolybdenumVanadium steel and chromium Vanadium steel. The advantages of silicon killed carbon steel (0.1 % silicon minimum) for temperature above 482 C (900 F) The possibility of damage due to hydrogen exposure at elevated temperature above 200 C (See API RPI 941), hydrogen damage (blistering) may occur at lower temperature under exposure to aqueous acid solutions. The possibility of stress corrosion cracking when exposed to cyanide, acids, acid salts, or wet hydrogen sulphide, a maximum hardness limit is usually specified in NACE; MR-0-175 & RP-047-2. The possibility of sulphidation in presence of hydrogen sulphide at elevated temperature. IS 1239 and IS 3589 Gr. 330 pipes should not be used above the maximum temperature 0 65 C and maximum pressure 13.0 Kg / cm2. Ball valves and plug valves can be used on any line up to a maximum temperature 200 0 C due to soft (Teflon) seat. Carbon steel pipe and piping components are permitted for prolonged use up to 426 0C. It is not permitted for prolonged use above 426 0C because the carbide phase of carbon steel may be converted to graphite. Low Alloy Steels (C-1/2 Mo) is not permitted for prolonged exposure above 450 0C because of carbide phase of carbon Molybdenum Steel may be converted to graphite. However, it should not be used above 537 0C. Any grade of steel material carrying hydrogen or hydrogen with hydrocarbons (A flammable, toxic/non-toxic but no lethal) have the limitation for use up to maximum temperature limit 260 0C and a maximum pressure limit of 5.60 Kg/cm2 due to hydrogen cracking and sulphide stress cracking. When materials are exposed to wet hydrogen sulphide, further deterioration (Sulphidation) in the presence of hydrogen sulphide at temperature above 260 0C takes place. ASTM A335 grades, such as P11, P12, and P22, Alloy Steel piping, components are not permitted to be used for prolonged above 593 0C due to susceptibility of grain boundary attack. This material should be normalized and tempered condition. All Austenitic Stainless Steels grade A312, TP 304, TP 316, and TP 321 are not permitted for prolonged use above 537 0C due to susceptibility to inter granular corrosion of Austenitic Stainless Steels. However, a stabilized and high carbon (0.04% or higher) grade, Austenitic stainless steels are permitted for use above up to 537 0C up to 871 0C such as TP 304H, TP 316H, TP 321H, TP 347H, and TP 348H. However, Austenitic Stainless Steels A312 grade TP 304L, TP 316L are not permitted for prolonged use above 426 0C. Nickel and nickel base alloy steels, not containing chromium, piping components are not permitted for use above 316 0C due to the grain boundary attack susceptibility in presence of sulphur. Aluminium and Aluminium Alloy pipes and piping components are not permitted for use above due to inter granular attack and low melting point. Pipes and piping components of other materials, which are given below, are not permitted for use above the temperature as mentioned against each material:
a) Titanium and Titanium Alloys maximum 3160 C. b) Zirconium and Zirconium Alloys maximum 3160 C. c) Tantalum maximum 2990 C. (iii) Material’s Condition: Ductile, Cast, wrought irons, Malleable irons or Nodular irons, as a general rule, are not used for piping and piping components in refinery or petrochemicals plant for toxic, hydrocarbons and flammable service. Cast irons are not permitted for use in piping for volatile, flammable, toxic or refrigerant services. (a) Ductile Irons: Ductile irons, such as ASTM A571 are not used for pressure containing parts at a temperature below –290C and above 3400C, except austenitic ductile irons. Austenitic ductile irons are used at a temperature below –290C down up to a temperature of Impact Test temperature but not below –1960C. (b) Cast Irons: Cast irons are not used in any pressure underground piping or in above ground, nonpressure piping for hydrocarbons, and toxic or flammable fluid service. Cast irons are not used above 1490C and not at gage pressure above 150 psi (1030 kpa). In other location and category “D” fluid service, it can be used up to 400 psi (2760 kpa). (c) Malleable Irons: Malleable irons are not used in any fluid service at a temperature below –290C or above 3430C. It is not used in hydrocarbon, toxic or flammable fluid service above 1490C or at a gauge pressure above 400 psi (2760 kpa). (d) Carbon Steel: ASTM A-53 grade pipe does not have specific limits on carbon content. It is used for low pressure piping work. API 5L grades pipes have closer control over the carbon content and hence produce more identical microstructures. So, it is used for high pressure, but at low temperature range piping work. ASTM A 106 grade pipes have closer control over carbon content, i.e. between 0.18 % to 0.25%) and also contain silicon, which produce a more identical microstructures. So, it is used for high pressure and high temperature range of piping like steam line. (e) Stainless Steels: The possibility of stress corrosion cracking of austenitic stainless steels exposed to media such as chlorides and other halides either internally or externally, the latter can result from improper selection or application of thermal insulation. The susceptibility to intergranular corrosion of austenitic stainless steels sensitised by exposure to temperatures between 427 C and 871 C (800 F and 1600 F); as an example, stress corrosion cracking of sensitised metal at room temperature by polyphonic acid (reaction of utilizable sulphur compound, water and air); stabilized or low carbon grades may provide improved resistance (see NACF RP 0170). The susceptibility to inter-crystalline attack of Austenitic stainless steels on contact with liquid metals (including aluminium, antimony, bismuth, cadmium, gallium, lead, magnesium, tin, and zinc) or their compounds. The brittleness of ferritic stainless steels at room temperature after service at temperature above 371 C (700 F). Piping which is operated continuously or intermittently at a temperature above 8000 F and also exposed to corrosive environment, are generally made of stabilized stainless steel grade 321, 347 and 348. (f) Alloys Steel:The susceptibility to grain boundary attack of nickel and nickel base alloys not containing chromium when exposed to small quantities of sulphur at temperatures above 316 C (600 F). The susceptibility to grain boundary attack of nickel base alloys containing chromium at temperatures above 593 C (1100 F) under reducing conditions and above 760 C (1400 F) under oxidizing conditions. The possibility of stress corrosion cracking of nickel-copper Alloy 400 in hydrofluoric acid vapour in the presence of air, if the alloy is highly stressed (including residual
stresses from forming or welding). (g) Aluminium Alloys:The compatibility with aluminium of thread compounds used in aluminium threaded joints to prevent seizing and galling. The possibility of corrosion from concrete, mortar, lime, plasters or other alkaline materials used in buildings or structures. The susceptibility of Alloy Nos. 5083, 5086, 5154 and 5456 to exfoliation or inter-granular attack; and the upper temperature limit 66 C (150 F) shown in Appendix A to avoid such deterioration. The possibility of fire hazard zone or in flammable services due to their low melting point. (h) Copper Alloys: The possibility of dezincification of brass alloys; The susceptibility to stresscorrosion cracking of copper-based alloys exposed to fluids such as ammonia or ammonium compounds; The possibility of unstable acetylates formation when exposed to acetylene. The possibility of fire hazard zone or in flammable services due to their low melting point. (i) Titanium Alloys: The possibility of deterioration of titanium and its alloys above 316 C (600 F). (j) Zirconium Alloys: The possibility of deterioration of zirconium or zirconium alloys above 316 C (600 F). (k) Tantalum Alloys: The possibility of reactivity of tantalum with all gases except the inert gases, below 299 C, the possibility of embrittlement of tantalum by nascent (monatomic) hydrogen (but not molecular hydrogen) nascent hydrogen is produced by galvanic action or as a product of corrosion by certain chemicals. (l) Welded Pipe: Furnace Welded, Furnace Butt-Welded, Special Welded and Fusion welded ferrous pipes made to ASTM A134, A1339, A120 and API 5LX are not permitted for hydrocarbons, flammable and Toxic fluid service in refineries and petrochemicals. Butt-Welded Carbon Steels or wrought Irons are not permitted for use in refrigerant liquid service of any service. (m) Acid Bessemer Process Steels Pipe: Pipe made of Acid Bessemer process steels are not permitted for use in piping work. Steel pipes made by open-hearth, electric furnace and basic-oxygen process are used in piping work. (n) Lead and Tin Alloy Pipe: Lead and Tin and their alloys are not used in flammable, hydrocarbon & toxic fluid service. (o) High Silicon Iron Pipe: High Silicon Irons (14.5% Si) is not permitted in flammable, toxic or hydrocarbon fluid service. (p) Low Allowable Stress Pipe: The listed materials, in the Allowable Stress List of ANSI B31.3, are not permitted for use at the design temperature higher than the maximum temperature for which stress value is shown or marked with double bar (II) symbols adjacent to it. Similarly, the materials are not permitted for use at a design temperature lower than the temperature for which the stress value is shown or marked with a double bar (II) symbols. (iv) Cost Factor Considerations Selection of materials has to be done on a compromise between the cost and the required properties of the materials. Designer always recommend Stainless steel in place of other steels because of corrosion resistance. The Relative Cost of various materials is given in the Table below which shows those Carbon Steels are about 5 to 10 times cheaper than the stainless steels. Table: Relative Cost of Various Materials S.No. Type of Materials 1 A312 Gr. 410,403,430
Relative Cost (Factor) 1.0
2 3 4 5 6 7 8 9 10 11
A312 Gr. 405,201,202 A312 Gr. 301, 302,403, 305 A312 Gr. 321 A312 Gr. 446 A312 Gr. 347, 309,316 A312 Gr. 310 17-7 PH, AM-350 Carbon Steel Low Alloy Steel Tool Steel
1.2 1.3-1.4 1.6 1.7 2.0 2.0 2.2-2.7 0.12-0.20 0.3-0.8 0.8-5.0
Selection of Materials Exercise 1: Assume a recovered material process line that handles nearly 100% ethyl benzene at 1.20 Pa (174 psig) and 250C (770F) is required to be installed above ground. Solution: The piping material is selected as follows: Step 1: Above ground handling of a flammable liquid by thermoplastic piping is not allowed by ASME B31.3. Step 2: Review of the Fluid/Material Corrosion Table Book for ethyl benzene at 250C (770F) indicates that aluminium, Hastelloy C, Monel, TP316 stainless steel, reinforced furan resin Thermoset and FEP lined pipe are acceptable for use. Step 3: Reinforced furan resin piping is available to a system pressure rating of 689 kPa (100 psig). Therefore, this material is eliminated from consideration. The remainders of the materials have available system pressure ratings and material allowable stresses greater than the design pressure. Step 4: FEP lined piping is not readily available commercially. Since other material options exist, FEP lined piping is eliminated from consideration. Step 5: The site-specific environmental conditions are now evaluated to determine whether any of the remaining materials out of aluminium, Hastelloy C, Monel or TP316 stainless steel should be eliminated prior to ranking. The material is then selected based on site-specific considerations and cost. (v) Code Restrictions Pipe dimensions should be in accordance with ANSI B36.10, IS 3589 and IS 1239 for Wrought Steel and Wrought Iron pipe. It should be as per ANSI B36.19 for Stainless Steel pipe. Pipe manufactured by Acid Bessemer process should not be used. The pipe manufactured by Open Hearth, Electric Furnace or Basic Oxygen process should be used in piping work. Any pipe material subjected to stress due to pressure should confirm to API, ASME/ANSI B31.3, Boiler and Pressure Vessel Code or IBR. The listed materials only should be used. The materials should not be used until the test certificate, having physical properties, chemical compositions and heat treatment or impact test and other requirements are reviewed and found in conformation with as required by the specifications. Pipes made of steels manufactured by Acid Bessemer process are not used. All austenitic stainless steel pipes should be solution-annealed condition. It should be tested for inter-granular corrosion test as per A262, Practice “B”. The corrosion rate should not exceed 40-mils/ year.
All pipes going to be used in Low Temperature Cryogenic Service (LTCS) should be impact tested at a temperature - 450C, -1010C, and -1960C for Carbon Steels, 3-0.5 Nickel Steel and all Austenitic Stainless Steel respectively. IBR Inspector should certify all IBR piping materials before use. The carbon Equivalent of all materials should be 0.25%. All pipes should be hydrostatically tested in the mill and should accompany by hydrostatic test certificate. IS 1239, IS 3589, API 5L Gr B, A106 Gr B are recommended. All pipes to be used in “IBR”, “CRYO” and “NACE” services should be painted longitudinally throughout the length of pipe in Red, Light Purple Brown and Canary Yellow strip respectively for easy identification during fabrication, erection and assembly. The paint should not contain Zinc, Lead, Copper metal or metallic salts as they cause corrosion attack on heating. (vi) Piping materials: a) Carbon Steel Pipe: API 5L, Grade A or B, seamless; API 5L, Grade A or B, SAW, straight seam, where Ej 0.95; API 5L, Grade X 42, Seamless; API 5L, Grade X 46, Seamless; API 5L, Grade X 52, seamless; API 5L, Grade X 56, Seamless; API 5L, Grade X 60, Seamless; ASTM A 53, Seamless; ASTM A 106, Seamless; ASTM A 333, Seamless ASTM A 369; ASTM A 381, where Ej 0.90; ASTM A 524; ASTM A 671, where Ej 0.90; ASTM A 672, where Ej 0.90; and ASTM A 691, where Ej 0.90. b) Alloy Steel Pipe:ASTM A 333, seamless; ASTM A 335, Seamless; ASTM A 369; ASTM A 426, where Ej 0.90; ASTM A 671, where Ej 0.90; ASTM A 672, where Ej 0.90; and ASTM A 691, where Ej 0.90. c) Stainless Steel pipe: ASTM A 268, seamless; ASTM A 312, seamless; ASTM A 358, where Ej 0.90; ASTM A 376; ASTM A 430; and ASTM A 451, where Ej 0.90. d) Copper and Copper Alloy pipe: ASTM B 42; and ASTM B 466. e) Nickel and Nickel Alloy pipe: ASTM B 161; ASTM B 165; ASTM B 167; and ASTM B 407. f) Aluminium Alloy Pipe: ASTM B 210, Tempers O and H112; and ASTM B 241, Tempers O and H112.
2.9 Piping Materials for Specific Fluid Services Types of Services: As per ANSI B 31.3, the fluid services have been classified in five different categories for sake of safe operation based on design conditions, design criteria, design consideration & design limitations. However, practically, the different fluid services are as mentioned below: ( I ) UTI LI TI ES S ERVI CE: COMMERCIAL CARBON STEEL PIPE SUCH AS IS 1239 IS COMMONLY USED IN UTILITY SERVICE. T HE STEEL PIPE WHICH IS OF A TYPE OR GRADE NOT ACCEPTABLE FOR HYDROCARBON SERVICE, SOME DEFINITE MARKING SYSTEM SHOULD BE ESTABLISHED TO PREVENT SUCH PIPE FROM ACCIDENTALLY BEING USED IN HYDROCARBON SERVICE. O NE WAY TO ACCOMPLISH THIS WOULD BE TO HAVE ALL SUCH PIPE GALVANIZED OR PAINTED IN STRIP TO FULL LENGTH OF PIPE. (ii) Category-D fluid: The fluid which design pressure is 150 psi or less with design temperature between –29ºC and 166ºC and do not damage to the human tissue or otherwise on exposure. Category-D Fluid is non-toxic and non-flammable. Piping is designed as per ANSI B 31.3, chapter I to VI for metallic and chapter vii for non-metallic and lined piping. The following carbon steel pipe can be used. ASTM A 53 GR F, ASTM A734 made from other than ASTM A 215 plate, API 5L GR B (Furnace Butt-welded), ASTM A 211 and ASTM A134 made from other than ASTM A285 plate. (iii) Category-M Fluid: The fluid service which operating pressure is not high. It is flammable or non-flammable, but toxic. It causes, by leakage to a very small quantity of the fluid, irreversible harm to the human on a single exposure. It cannot be designed under code or under chapter VII sufficiently to protect personnel from exposure to a very small quantity of the fluid in environment. Category-M fluid service piping is designed by chapter VIII rules of ANSI B 31.3. Sufficient safeguarding shall be provided to the piping for category-M fluid service. Category-M fluid service piping shall not be designed or used under severe cyclic conditions and high-pressure piping. Category-M fluid service piping shall be avoided with dynamic effects such as impact caused by external or internal conditions (e.g., change in flow rate, hydraulic shock, and liquid or solid slugging, flushing and geysering) and also vibrations, which may arise from pressure pulsation, resonance in compressor or wind loads. ASTM A 134 and ASTM A 139 pipe shall not be used. Fittings confirming to MSS SP-43 and proprietary “Type C” lap-joint stub end butt-welding fittings shall not be used in category-M fluid service. Creased or corrugated bends shall not be used. Threaded or sockets welding outlet branch connections are not permitted to be used. Flat closures (blanks) shall not be used. Valves having threaded bonnet joints shall not be used. Valve bonnet or cover plate closures shall be flanged, secured by at least four bolts with proper gaskets to stop the stem leakage to the environment. Singlewelded slip-on flanges, Expanded joint flanges, Lap joint flanges and threaded flanges shall not be used. Socket welded joints greater than 1 ½” size shall not be used. Expansion joints shall not be used. (iv) Normal fluid service:This is a fluid, which is not at high pressure but whose design pressure or design temperature is not limited to 150 psi or between –29 C to 166 C respectively. This is toxic or non-toxic, flammable and damage to the human tissue on exposure or irreversible damage on single exposure. It is designed and constructed per chapter I to VI for metallic piping, per chapter VII for non-metallic and lined piping to sufficiently protect personnel from exposure to very small quantities of the fluid in the environment. Any pipe and piping components listed in codes & specifications may be used in “Normal Fluid Service”. Unlisted piping component material may be used only after qualifying the design conditions and criteria and other design parameters.
(v) Severe Cyclic Condition Fluid service: The fluids, which do not have very high pressure but toxic, non-flammable and produce a serious irreversible harm on a single and very small quantity exposure. Fluid comes under “Category-M fluid” but can be designed and constructed in severe cyclic conditions to prevent occurrence of it as per Chapter VIII rule, is called severe cyclic condition fluids. This fluid service cannot be designed on experience, service conditions & location involved, as per base code or chapter VII sufficiently to protect personnel from exposure to very small quantities of the fluid in the environment. The following pipe may be used under severe cyclic condition fluid service. (vi) High Pressure Fluid service: High pressure is considered to be pressure in excess of that allowed by the ASME B16.5 PN 20 (class 2500) rating for the specified design temperature and material group. Non-metallic or metallic lined piping components are not permitted for use in high pressure piping category. There is no provision for category-M fluid service in high-pressure piping. The design of High Pressure piping should be done as per following considerations: Mitre bend shall not be used in high-pressure piping. Pipe to pipe cut & welded branch connections shall not be used in high-pressure piping. All welded pipes or cast-forged fittings shall have joint quality or cast quality factor not less than 1.0. (vii) Steam Tracing (NIBR): Certain process lines, tanks, vessels, are required to be heated up constantly to prevent the fluid passing through the lines, stored tank or vessel from freezing. Heating keeps the temperature high enough for free flows of fluid and proper pumping ability. Heating is done with the help of steam tracing or electrical tracing. Steam tracing is done by running one, two, or three lines parallel along the process line at equal distance on periphery of the lines and touching the line or inside the tank or vessels to be heated up. Process lines shall be indicated to be traced in the line list system. Steam supplies for tracing are obtained from process steam lines or independent steam supplies line, exhaust bleed steam or from other continuous source of steam supply lines. Steam supply shall be always available even if other unit or steam lines are under shutdown or out of operation. Minimum steam pressure for tracing shall be 1.5 kg / cm2 and maximum steam pressure shall be 3.5 kg / cm2. The minimum steam temperature shall be the saturation temperature at the given pressure. The size of steam supply header shall be 3” Dia. (80 mm) Maximum for header and ½” Dia. for steam tracing line, running along the process line. The number of tracers along the process lines for heating shall be as per design calculation by the designer. However, under normal condition of heating the number of tracers lines shall be mentioned below: Tracer line size 4” NB and smaller 6” NB to 16” NB 18” NB and larger
Number of ½” Dia. Tracers 1 2 3
The useful length of tracer line in a single run at a steam pressure of 3.5 Kg /cm2 shall be maximum as mentioned below: 1. Open system of tracing 2. Closed system of tracing
- 40 meter max. (With no recovery). - 25 meter max (With condensate recovery).
The tracer loops shall start at the highest point and terminate at lowest point in the system, in general. But sometimes there is an unavoidable pocket in the tracers. The sum of all pockets in a loop of tracer shall be proportionate to the differential steam pressure in the tracer (i.e., maximum 3.5 Kg /cm2) to max total sum of vertical depth of pocket (i.e., max. 3000 mm). Example: The total depth of pockets in above diagram is A + B + C. Every tracer shall be provided with a separate steam trap at the end at lowest point. (viii) Non-Corrosive Hydrocarbon Service: The most commonly used types of pipe are ASTM A106, Grade B, and API 5 L, Grade B. ASTM A106 is only manufactured in Seamless while API 5 L is available in Seamless, Electric Resistance Welded (ERW) and Submerged Arc Welded (SAW). When API 5L, Grade B, pipe requires excessive wall thickness, higher strength pipe such as API 5LX, Grade X52, may be used. However, special welding procedures and close supervision are necessary when using API 5LX, Grade X46 or higher. ANSI B 31.3 specifically excludes the following types or grades of pipe from hydrocarbon service: All grades of ASTM A 120. Furnace lap weld and furnace butt weld. Fusion welds per ASTM A 134 and A 139. Spiral weld, except API 5LS. (ix) Corrosive Hydrocarbon Service: Design for corrosive hydrocarbon service should provide for one or more of the following corrosion mitigating practices: 1) Chemical treatment; 2) Corrosion resistant alloys; 3) Protective coatings. Chemical treatment of the fluid in contact with carbon steels is by far the most common practice and is generally adopted. Corrosion resistant alloys, which have proven successful, may be used. If such alloys are used, careful consideration should be given to welding procedures and the possibility of sulphide and chloride stress cracking. Adequate provisions should be made for corrosion monitoring (coupons, probes, spools etc.,) and chemical treating. API 5L GR B, A106 GR B, A312 GR TP 304, TP 316, TP 316L are recommended. (x) Sulphide Stress Cracking Service: The following guidelines should be used when selecting pipe if sulphide stress corrosion cracking is anticipated; Only seamless pipe should be used. Cold expanded pipe should be used only after normalizing, quenching and tempering, or heat treatment. Carbon steels, alloy steels and other materials which meet the property, hardness, heat treatment and other requirement of NACE: MR- 01-75 is acceptable for use in sulphide stress cracking service. The most commonly used pipe grades which will meet the above guidelines are: ASTM A106, Grade B; ASTM A333, Grade 6 and API 5L, Grade B, seamless and API 5LX is also acceptable. Welding of this grade material presents special problems. To enhance toughness and reduce brittle fracture tendencies, API 5L and 5LX should be normalized for service temperatures below 30 F. ASTM A333, Grade 6, is a cold service piping material and should have adequate notch toughness in the temperature range (- 20 to 650 F). (xi) Steam (IBR) Service: Central Boiler Board in India exercises the material, design and construction of a boiler steam pipe, economizers, or super heaters. The representative of Central Boiler Board is the Chief Inspector of Boiler in the state of India. To exercise the power to supervise the job, the Central Boiler Board has made Regulations, which control the materials, design, construction, and inspection of the work. This Regulation is called “Indian Boiler Regulation-1950” or “IBR”.
The chief inspector will register the work under boiler regulation, subject to the following conditions: (i) Boilers: When a closed vessel, exceeding 22.75 litres (five gallons) in capacity, and which is used expressly for generating steam under pressure and include any mountings and fittings is called Boiler and comes under Indian Boiler Regulation. (ii) Economizer: When a feed pipe, wholly or partly exposed to the action of flue gases for the purpose of recovery of waste heat is called Economizer and comes under Indian Boiler Regulation. (iii) Steam Pipe: When a pipe through which steam passes from boiler to a prime mover or other users or both, and, if, satisfy the following conditions, (a) the pressure at which steam passes through such pipe, exceeds 3.5 kg/cm2 above atmospheric pressure, or (b) the internal diameter of the steam pipe exceeds 254 mm, it is called a Steam Pipe and comes under Indian Boiler Regulation. In any industry, if there is a boiler, economizer, and steam pipe or all of them, then the design, materials, fabrication, the Chief Inspector of Boiler does erection and hydrostatic testing. The total package of above nature of work has to be offered to the Chief inspector of Boiler for approval of the package including materials, fabrication, and erection and testing. A completion certificate has to be obtained by the manufacturer from the office of the Chief Inspector of Boiler as per IBR code requirements. Limitations on selection of IBR materials: IBR Inspector of the Central Boiler Board of India should certify all IBR piping materials in the form III before use. Carbon Equivalent (CE): The Carbon Steel IBR piping materials should have Carbon Equivalent Maximum 0.25%. (xii) Sour Service: Sour service is the hydrocarbon service containing hydrogen sulphide. The presence of Hydrogen sulphides causes Sulphide Stress Cracking (SSC) of metallic material in wet conditions. The standard NACE MR-01-75 defines the sour service and recommends materials, which will not fail in wet sour service fluid conditions. The following recommended materials minimize SSC but also HIC (Hydrogen Induced Cracking), Step-Wise cracking or Hydrogen Blistering. All materials should be quenched & tempered or normalized condition or normalized & tempered condition. Pipes: API 5L Grade B (seamless) & SAW (Longitudinal); A 106 Grade B (seamless), A 333 Grade 6 (seamless); A 671 Grade CC 70 CL 32- SAW (Longitudinal); A672 Grade CC 70 CL 32- SAW (Longitudinal); API 5L Gr. X 52, X60, SAW (Longitudinal); Studs/Nuts: A 193 Gr. B7M; A 194 Gr. 2HM; A 320 Gr. L7M; A 194 Gr. 7M; Studs should be fully threaded with two nuts. HIC test and SSC test are not required for studs and nuts. Castings: A216 Gr. WCB; A217 Gr. WC6; A351 Gr. CF3M Fittings: A 234 Gr. WPB (SMLS); A420 Gr. WPL6 (SMLS); A105 (Forged); SS-SP-75 Gr. WPH452 (Welded); A 234 Gr. WPBW / WPCW (Welded); A350 Gr. LF2 (Forged); MSS-SP-75 Gr. WPH460 (Welded). Gaskets: Spiral wound gaskets of SS 316 L with Compressed Asbestos (CA) filler should be used. In case of RTJ type, the gasket should be Soft Iron with maximum hardness 90 BHN. HIC & SSC tests are not required.
Flanges:
A694 Gr. F52; MSS-SP-44 Gr. F60; A105; ASTM 350 Gr.
LF2; Valves: Valve body should be cast or forged steel. Other component and TRIM materials should be SS 316 with maximum hardness RC 22 and hard faced with Stellite hardness up to maximum RC 43. All part of the valve should be stress relieved. A105 (Forged); A216 Gr. WCB (Casting); A352 Gr. LF2 (Forged); A352 Gr. LCB (Casting) Limitation for Material Metallurgy Sour Service: All steel should be fully killed and fine-grained and should have high resistance to hydrogen sulphide attack such as “HIC” & “SSC”. All steels should be produced either by basic oxygen or Electric Furnace process only. All steels should have following treatment during steel making process: Steel should be treated to have low sulphur and low Phosphorus and should be vacuum degassed. Steels should be calcium treated for morphology control. Steels should be treated to avoid inclusions like metallic oxide clusters, silicates, magnesium sulphide etc. Steels should be rolled and heat treatment should do so as to eliminate “low temperature transformation of microstructures associated with segregation”, such as binate Band or Islets or Martensite in order to reduce the propagation of HIC. Carbon Equivalent (C.E): Carbon Equivalent (C.E) and Pcm should be as per Table indicated below and should be computed by following formulas: If c = < 0.12;
The weld ability based on a range of CE values can be defined as follows: Carbon equivalent (CE) Up to 0.35 0.36–0.40 0.41–0.45 0.46–0.50 Over 0.50
Weld ability Excellent Very good Good Fair Poor
Material Test Requirement Sour Service: The manufacturer should carry out all the following test duly witnessed by Third party inspection agency and shall conform to the requirement given in following table: Chemical compositions as given in table below. Mechanical properties such as UTS & ratio of Yield to Tensile Strength and following should be acceptable. UTS = 77000 PSI (max.)
Ratio of Yield to Tensile Strength should not exceed 0.8. Hardness should be maximum RC 22 or 248 HVs or 237 BHN for each heat. Longitudinal weld seam should be 100% radiographic. Repair welds should not be permitted of any size. All valves casting should be 100% radiograph and acceptance limit should be as per B16.34, Annexure-B. Seamless pipe for Sour Service: Maximum sulphur and phosphorus content should be 0.01% and 0.02% respectively. If the sulphur and Phosphorus content is more than the above limit specified, the HIC testing should be carried out on pipe where the content exceeds the above value. Welded pipe for Sour Service: HIC should be compulsorily carried out for each welded pipe irrespective of sulphur and phosphorus content value. The acceptance criteria should be as follows: i. CSR =< 0.00% ii. CLR =< 10.00% SSC Test for Sour Service: SSC test is not required, but when the sulphur and phosphorous contents exceeds 0.020% and 0.010 % (for seamless) or 0.003% (for welded) respectively then SSC test should be compulsorily carried out for acceptance of the pipe for every heat. Similarly, when UTS is greater than 77000 psi (54 Kg/mm2), SSC test is compulsorily for acceptance of the pipe for every heat. The acceptance criteria should be as follows: AT 72% of SMYS,” Time to failure”, should not be less than 720 hrs. Corrosion Tests for Sour Service: The corrosion tests should be carried out compulsorily for the material. Table: Chemical Composition of Materials for Sour Service Sl.no Item
1
2
3
4
5
C
Mn Si P Ni S % % % % % % Pipe 0.23 1.35 0.10 .02 0.2 0.010 to SMLS 0.25 0.003 Weld Fitting 0.23 1.35 0.10 .02 0.2 0.10 to SMLS 0.35 0.003 Weld Flange 0.23 1.35 0.10 .02 0.2 0.01 to 0.35 Valve 0.23% 1.35 0.10 .02 0.2 0.01 to 0.35 Soft 0.24 1.35 0.35 .02 .24 0.01 iron Ring gasket
Pcm CE % % 0.21 0.40
0.25 0.40
0.25 0.40
0.25 0.4
-
-
(xiii) Cryogenic Service: The Cryogenic Service has been defined for proper piping design handling the material at cold temperature. The temperature level, for a cryogenic fluid service, starts at –100 0 F to absolute zero, i.e. –459.7 0 F. There are many factors being encountered while handling the cryogenic fluid because they are cold. The cryogenic fluids include the liquefied gases like oxygen, nitrogen, helium, methane, and carbon dioxide, Argon and to make certain metals super conductive. Cryogenic fluids are used to cool any product to produce physical changes i.e. to liquefy gases and to manufacture gases such as Oxygen, Nitrogen, Helium and Methane and to make certain metal super conductive. Cryogenic system handles following fluids at low temperature. It absorbs heat from outside source and tends to vaporize or saturated vapour gets superheated. This increases the pressure in the vessel. Cryogenic fluids are very limited, such as, Acetylene; Air and Argon. In general, the following table shows the materials commonly used in low temperature Cryogenic service: Temperature Range, 0F Material 0 to –20 Carbon Steel ASTM A333 Gr.3, Gr. 6, API 5L Gr.B -20 to –50 Carbon Steel (Aluminium Killed), ASTM A333 Gr.6 -50 to –150 Alloy Steels, ASTM A333 Gr.3 -150 to –320 Alloy Steels or Non-Ferrous, ASTM A312 Gr.TP304 Below –320 Non-Ferrous, ASTM A312 Gr.TP304
2.10
Pipe Material Identification
Pipes in exposed areas and in accessible pipe spaces shall be provided with colour band and titles adjacent to all valves at not more than 12 m (40 ft) spacing on straight pipe runs, adjacent to directional changes, and on both sides where pipes pass through wall or floors. Piping Material identification is specified based on CEGS 09900, which provides additional details and should be a part of the contract documents. Table 3-6 is a summary of the requirements Table: Colour Codes for Marking Pipe MATERIAL
BAND and ARROW LETTERS
LEGEND
Cold Water (potable)
Green
White
Fire Protection Water
Red
White
Hot Water (domestic) Hot Water recirculation (domestic) High Temp. Water Supply High Temp. Water Return Boiler Feed Water Low Temp. Water Supply (heating) Low Temp. Water Return (heating) Condenser Water Supply Condenser Water Return Chilled Water Supply Chilled Water Return Treated Water Chemical Feed Compressed Air Natural Gas Freon Fuel Oil Steam
Green Green
White White
POTABLE WATER FIRE PR. WATER H. W. H. W. R.
Yellow
Black
H. T. W. S
Yellow
Black
H.T.W.R.
Yellow Yellow
Black Black
B. F. L.T.W.S.
Yellow
Black
L.T.W.R.
Green
White
COND. W.S.
Green
White
COND. W.R.
Green Green Yellow Yellow Yellow Blue Blue Yellow Yellow
White White Black Black Black White White Black Black
C.H.W.S. C.H.W.R. TR. WATER CH. FEED COMP. AIR NAT. GAS FREON FUEL OIL STM.
Condensate
Yellow
Black
COND.
3 Corrosion of Metal
3.1
Theory of Corrosion
According to the modern theory, there are three major factors, such as, Chemical, Electrochemical and Physical. All this differs according to the degree of involvement of the “ions”, “electrons”, and “atoms”. For example, There is a common representation of the corrosion reaction and is expressed with respect to iron, water, and oxygen in the chemical reaction: Fe + H2O + ½ O2 ---Fe (OH) 2 Cause of Corrosion: There are ten most common causes of corrosion of metals, such as, (a) General corrosion, (b) Galvanic corrosion, (c) Electro-chemical corrosion, (d) Concentration Cell Corrosion, (e) Pitting Corrosion, (f) Inter-granular Corrosion, (g) Stress corrosion cracking, (h) De-alloying Corrosion, (i) Erosion Corrosion, and (j) Microbial Induced Corrosion(k) Crevice corrosion, (l) Graphitic Corrosion, and (m) Graphitic Corrosion. (b) Galvanic Corrosion: Galvanic corrosion can occur when two electrochemically-dissimilar metals or alloys are metallically connected and exposed to a corrosive environment. The less noble material (anode) suffers accelerated attack and the more noble material (cathode) is protected by the galvanic current. In order to have a galvanic cell, only a metallic path for electron flow is needed; this is provided when the two dissimilar materials are metallically connected. Example: Zinc is often used as a sacrificial anode for steel structures or piping. Galvanic corrosion is of major interest to the marine industry (sea water) and also anywhere in salt water with contacts of pipes or metal structures. (c) Electro-chemical corrosion: Corrosion occurs by an electrochemical process. Basically, an anode (negative electrode), a cathode (positive electrode), electrolyte (corrosive environment), and a metallic circuit connecting the anode and the cathode are required for this type of corrosion to occur. Dissolution of metal occurs at the anode where the corrosion current enters the electrolyte and flows to the cathode. Examination of this basic reaction reveals that a loss of electrons, or oxidation, occurs at the anode. Electrons lost at the anode flow through the metallic circuit to the cathode and permit a cathode reaction to occur. Practically all corrosion problems and failures encountered in service can be associated with one or more of the following basic forms of corrosion. (d) Concentration Cell Corrosion: Electrochemical attack of a metal or alloy because is called concentration cell corrosion. Concentration Cell Corrosion occurs where the surface is exposed to an electrolytic environment due to the concentration of the corrosive fluid or the dissolved oxygen varies. This is often combined with stagnant fluid or low fluid velocity. There are at least five types of concentration cells. Of these, the “oxygen” and “metal ion” cell are most commonly considered in the technical literature. (e) Pitting corrosion: Pitting Corrosion occurs due to stagnant fluid or low fluid velocity. The metal loss is randomly located on the metal surface. Certain conditions, such as low concentrations of oxygen or high concentrations of species such as chloride which complete as anions, can interfere with a given alloy's ability to re-form a passivation film. In the worst case, almost all of the surface will remain protected, but tiny local fluctuations will degrade the oxide film in a few critical points. Corrosion at these points will be greatly amplified, and can cause corrosion pits of several types, depending upon conditions. These problems are especially dangerous because they are difficult to detect before a part or structure fails. Pitting is similar to concentration cell-corrosion in many respects. Many grades of stainless steel are particularly susceptible to pitting corrosion when
exposed to saline environments. Alloying elements in a stainless steel, however, greatly affect its resistance to pitting attack; the tendency to pit decreases as the content in nickel, chromium, and molybdenum increases. In sea water, austenitic stainless steels containing 18% chromium and a 2-3% molybdenum addition (e.g., Type 316 stainless steel) exhibit much better pitting-corrosion resistance than similar alloys which contain no molybdenum (e.g., Type 302 stainless steel). (f) Inter-granular Corrosion: Inter-granular corrosion is the localized attack, which occurs at or in narrow zones immediately adjacent to the grain boundaries of an alloy. Severe inter-granular attack usually occurs without appreciable corrosion of the grains; eventually, the alloy disintegrates or loses a significant amount of its load-bearing capability. Although a number of alloy systems are susceptible to inter-granular attack, most of the problems encountered in service involve austenitic stainless steels and the 2xxx and 7xxx series aluminium alloys. Welding, stress-relief annealing, improper heat-treating, or overheating in service generally establish the microscopic, compositional in-homogeneities which make a material susceptible to inter-granular corrosion. Several grades of austenitic stainless steels are susceptible to inter-granular corrosion after they have been heated into the temperature range of about 4250C to 7900C. It reveals that inter-granular corrosion can occur in many environments where austenitic stainless steels normally exhibit excellent corrosion resistance. (g) Stress-Corrosion Cracking: Stress-corrosion cracking, i.e. environmentally-induced Delayed failure, describes the deleterious phenomena, which can occur when many alloys are subjected to static, surface tensile stresses and exposed to certain corrosive environments. Cracks are initiated and propagated by the combined effect of a surface tensile stress and the environment. When stresscorrosion cracking occurs, the tensile stress involved is often much less than the yield strength of the material; the environment is generally one in which the material exhibits good resistance to general corrosion. For example, various steels have good general corrosion resistance to anhydrous liquid ammonia. Steel tanks are widely and successfully used for the storage and transport of this liquefied gas. Stress-corrosion cracking failures have occurred in some large-diameter liquid ammonia tanks, however, probably because the high residual tensile stresses introduced during fabrication were not removed by stress-relief annealing. Several of the alloy/susceptible environment combinations where stress-corrosion cracking can occur. (h) De-alloying Corrosion: De-alloying is a corrosion process wherein one element is preferentially removed from an alloy. The affected areas become brittle, weak, and porous but the overall dimensions of the component do not change appreciably. The two most important examples of dealloying are the preferential removal of zinc from copper-zinc alloys (dezincification) and the preferential removal of iron from gray-cast iron (graphitic corrosion). Other cases of de-alloying include the preferential removal of aluminium, nickel, and tin from copper-base alloys and cobalt from a Co-W-Cr alloy. Dezincification commonly occurs when yellow brass (67Cu-33Zn) is exposed to waters having a high chloride content, low temporary hardness, and pH above 8. For severe applications, it may be necessary to use Cupro-nickel alloys (90Cu-10Ni), which contains a small amount of iron. (i) Erosion Corrosion: Most metals and alloys depend upon a protective surface-film for corrosion resistance. When the protective film or corrosion products have poor adherence, an acceleration or increase in the rate of localized corrosion can occur because of relative movement between the liquid and the metal. Many metallic materials are susceptible to erosion corrosion at sufficiently high flow rates or excessive turbulence. Some of the piping components where erosion-corrosion damage frequently occurs include: elbows, tees, bends, and pump impellers, valves, and propellers, orifices of measuring devices, nozzles, heat-exchanger tubes, and turbine blades. Cavitations corrosion is a
special form of erosion corrosion. The process is basically the result of gas bubbles forming at low pressure and collapsing under high pressure at or near the liquid-metal interface. Bubble collapse, which produces very high-localized pressures (shock waves), destroys the metal’s protective film. Alternately, formation and destruction of the film on a localized basis results in severe damage of the metal. Cavitations corrosion damaged surfaces are characterized by their deeply pitted and “spongy” appearance. (j) Microbial corrosion: Microbiological activity can induce corrosion as a result of by-products such as carbon dioxide, hydrogen sulphide, ammonia, and acids. In some instances micro organisms may also consume metal. Biological activity can be reduced through the use of biocides, inhibitor and/or occasional pH variations. Microbial corrosion, or commonly known as microbiologically influenced corrosion (MIC), is a corrosion caused or promoted by micro organisms, usually chemoautotrophy. It can apply to both metallic and non-metallic materials, in the presence or absence of oxygen. Sulphate-reducing bacteria are active in the absence of oxygen (anaerobic); they produce hydrogen sulphide, causing sulphide stress cracking. In the presence of oxygen (aerobic), some bacteria may directly oxidize iron to iron oxides and hydroxides, other bacteria oxidize sulphur and produce sulphuric acid causing biogenic sulphide corrosion. Accelerated Low Water Corrosion (ALWC) is a particularly aggressive form of MIC that affects steel piles in seawater near the low water tide mark. Corrosion rates can be very high and design corrosion allowances can soon be exceeded leading to premature failure of the steel pile. Piles that have been coating and have cathode protection installed at the time of construction are not susceptible to ALWC. For unprotected piles, sacrificial anodes can be installed local to the affected areas to inhibit the corrosion or a complete retrofitted sacrificial anode system can be installed. (k) Crevice corrosion: Crevice corrosion creates pits similar to pitting corrosion. Crevice corrosion is a localized form of corrosion occurring in confined spaces (crevices) to which the access of the working fluid from the environment is limited and a differential aeration cell is set up, leading to the active corrosion inside the crevices. This form of corrosion is sometimes referred to as “Concentration Cell Corrosion”. Examples of crevices are gaps and contact areas between parts, under gaskets or seals, inside cracks and seams, spaces filled with deposits and under sludge piles. The susceptibility to crevice corrosion can be evaluated with ASTM standard procedures. A critical crevice corrosion temperature (CCT) is commonly used to rank a material's resistance to crevice corrosion. Crevice Corrosion occurs at places with gaskets, bolts and lap joints. (l) Graphitic Corrosion: Graphitic Corrosion is a process of Cast iron loosing iron in salt water or acids, which leaves the graphite in place, resulting in a soft weak metal. (m) Weld decay and knife line attack Corrosion: Stainless steel can pose special corrosion challenges, since its passivation behaviour relies on the presence of a major alloying component (Chromium, at least 11.5%). Due to the elevated temperatures of welding or during improper heat treatment, chromium carbides can form in the grain boundaries of stainless alloys. This chemical reaction robs the material of chromium in the zone near the grain boundary, making those areas much less resistant to corrosion. This creates a galvanic couple with the well-protected alloy nearby, which leads to weld decay (corrosion of the grain boundaries in the heat affected zones) in highly corrosive environments. A stainless steel is said to be sensitized if chromium carbides are formed in the microstructure. A typical microstructure of a normalized type 304 stainless steel shows no signs of sensitization while heavily sensitized steel shows the presence of grain boundary precipitates. The dark lines in the sensitized microstructure are networks of chromium carbides formed along the grain boundaries. Special alloys, either with low carbon content or with added carbon "getters" such as
titanium and niobium (in types 321 and 347, respectively), can prevent this effect, but the latter require special heat treatment after welding to prevent the similar phenomenon of knife line attack. As its name implies, corrosion is limited to a very narrow zone adjacent to the weld, often only a few micrometers across, making it even less noticeable.
3.2
Factors Affecting Corrosion
Temperature Effect: At an elevated temperature, the oxidation of the metal tends to occur fast and cause corrosion of the metal. However, at elevated temperature, the alloy steels have more oxidation resistance due to presence of the chromium in high percentage. The increase in the temperature, generally, increases the corrosion rate. The kinetics (rate of motion or reaction) of the action increases with the increase of temperature. Potential (Emf) Difference: The tendency of the metal to enter into solutions a function of electrode potential of the metal. Electrode potential is an inherent property of each element. When there is a difference in potential between two metals exposed in the same environment, the metal higher in series (Zinc in case of Steel and zinc) will corrode and protect the metal lower in the series, i.e. steel. Heat Treatment: The corrosion behaviour of many alloy steels can be strongly influenced by its heat treatment. Surface Condition: The cleanliness of the surface, existence of the surface films, and presence of foreign matter can affect the initiation of corrosion and rate of corrosion in different way. Effect of Erosion: The corrosion is directly proportional to the flow rate (velocity) of the liquid passing through the pipe. More is the flow; there is more corrosion due to the erosion of the corrosion resistance films getting washed away at faster rate. Erosion removes the corrosion films from the surface of metal, which act as protective coating of a substrate. Thus erosion exposes a fresh metal surface to corrode and thereby accelerate the corrosion. Radiation: Test has revealed that there is a slight additional increase in corrosion due to radiation. Environmental Impurities: It is a very important factor to affect the corrosion of metal. Time: The extent of corrosion, certainly, increases with increase of the time. Effect of Stress: Test has revealed that a material corrodes more when it is under tensile stress. The major concern is the cracking of a metal or plastic under the combined effect of tensile stress and corrosion to produce a brittle failure of the material. Pressure: Pressure does not have any effect on corrosion unless the liquid under pressure is corrosive. Differential Aeration: When a metal is exposed to an aerated liquid, it will corrode if there is an electrical path through the liquid. Concentration Difference: The action of the chemical like acid or base is based on degree of ionization. The strong acid like HCL ionizes more than weak acid like boric acid and hence HCL acid is more corrosive. When there are differences in concentration or pH of corrosive liquids in contact together with the metal surface, then the metal will corrode between the zones exposed to the differing solutions. Biological Effects: Macro and microscopic organisms influence corrosion of metals in two different ways, (1) by creating mats or obstructions on the surface which produce differential aeration cells, or (2) by absorbing hydrogen from the surface of steel and thus removing the hydrogen as a resistance factor in corrosion cell.
3.3
Corrosion Table
The piping materials as mentioned in the table below are recommended based on various effects of fluids on metals. This information have been collected from various books, specifications and compiled here for initial knowledge on corrosion of the metals. This corrosion table is prepare with the help of a book known as “CORROSION TABLE” and other book on corrosion to assist to have information of the corrosive fluids and their effect on different metals. The table is not intended for reference for design of the piping. It is a sincere advice to the reader to refer the authentic book “CORROSION TABLE” for authenticity of the corrosion requirement of the materials. Since the corrosion is a function of temperature, the table indicates the suitability of each material at varying temperatures. The symbols used to indicate specific corrosion rate are shown here below: The Corrosion Resistance of material is different at different temperature for the same fluid. Accordingly, a suitable abbreviation is selected to denote the different corrosion resistance as mentioned below: Excellent (E): When the corrosion rate is less than 2 mils penetration per year, it is called “Excellent” and is denoted by “E”. Good (G): When the corrosion rate is less than 20 mils penetration per year, it is called “Good” and is denoted by “G”. Satisfactory (S): When corrosion rate is less than 50 mils penetration per year, it is called “Satisfactory” and is denoted by “S”. Unsatisfactory (U): When corrosion rate exceeds 50 mils penetration per year, it is called “Unsatisfactory” and is denoted by “U”. Example: See the ‘corrosion table’ below for the fluid service “Ammonia Gas”. For Carbon Steel/Alloy Steel Grade material, it is written, as “E/38”. This shows that the corrosion resistance of carbon steel/alloy steel is Excellent up to 380C in Ammonia Gas service. Similarly, stainless Steel grade 304 & 347 are Excellent up to 940C, Stainless Steel grade 316 is Excellent up to 940C, Aluminium is Satisfactory up to 260C, and Monel is Unsatisfactory at any temperature for the same fluid. Table: Corrosion of Metal under influence of fluids
(CORROSION TABLE) Fluid service
Acetylene Air
Corrosion Resistance: Excellent (E), Good (G), Satisfactory (S) & Unsatisfactory (U)/ up to max. Limit of Temp. 0C Carbon Stainless Stainless Aluminium Monel Steel/ Steel Steel Alloy Grade 304, Grade 316 Steel 347 G/204 E/204 -E/180 -G/ 65 -----
Ammonia (Anhydrous) Ammonia Chloride (Sat.) Ammonia Gas Ammonium Phosphate Asphalt Bear Benzene, Benzyl Benzene Sulphurric Acid (10%) DO (100%)
E/204
G/249
E/293
E/82
--
--
--
--
--
G/260
E/38 U
E/94 E/58
E/94 E/58
S/26 U
U G/95
G/15 G/28 G/60
G/116 E/93 G/106
G/293 E/149 G/193
E/15 E/149 E/149
-E/149 E/94
U
G/100
--
U
G100
--
G/100
G/82
U
G/100
Bleach (12.5%) Active Chlorine Blood Borax Boric Acid Bromine Gas (DRY) Bromine Liquid Butadiene Butane Butyl Alcohol
U
U; Hastelloy- U C/C E/65
U
U
U G/93 U U
E/293 E/65 G/204 U
E/293 E/204 G/204 U
E/293 U E/38 G/15
E/293 E/30 G/95 E/49
--
--
U
G/95
--
G/85 E/175 G/93
G/85 G/82 G/93
G/204 G/149 E/204
-E/82 E/93
Butyl Ether Butyl Phenol Butylenes (Butadiene) Butyric Acid (WET) 20% Calcium Carbonate Calcium Chloride (SAT.)
E/15 -G/26
-G/200 G/82
E/15 E/200 G/204
G/40 G/82 E/40;G/4095 E/15 G/26 G/40
U U U G/93
G/75 U U E/95
G/204 U U E/95
G/82 G/26 U S/26
G/95 U U G/93
G/60
--
G/95
G/38
G/175
-G/95 E/26
Calcium Oxide Camphor Cane Sugar Liquid Carbon Dioxide (DRY) Carbon Monoxide Castor Oil Caustic Potash Chloramines (Dilute) Chlorine gas (DRY) Chlorine Liquid Chlorine Water (SAT) Chloroform
--G/75
G/30 E/30 G/30
-E/95 G/175
G/30 E/30 E/95
G/30 E/95 E/30
G/95
G/95
G/293
E/293
E/293
G/293
E/293
E/293
E/293
E/293
G/49 U U
-E/75 (50%) G/104 G/71 ---
G/95 U --
E/82 -U
G/93
U
G/204
G/95
E/95
G/26
G/40
G/49
--
G/65
U
U
U
G/26
U
U
E/95
Citric Acid (Concentrate) Citric Acid (5%) Coconut Oil Coffee Coke oven Gas Copper Sulphate Corn Oil Cotton Seed Oil Crude oil Cyclohaxane Cyclohexanol DO (WET) DO (10%)
U
G/26
U
E/65
E/30,G/30- -E/95 95 G/204 G/15,S/15- G/26 170 E/93 E/65 G/65
S/38 U G/38 U
G/38 G/95 G/38 G/95
G/38 G/95 G/38 G/204
G/38 -G/38 U
G/38 E/38 G/38 S/30
G/75 G/75
-G/30
G/175 G/75
G/75 G/75
G/40 E/15
G/38 G/82 G/26 S/75 U
E/95 G/38 G/26 G/95 G/93
E/95 G/204 G/26 G/93 E/204
E/40 G/82 G/26 E/204 G/82
DO (15%)
U
E/95
Detergent
G/26
E/60,G/6095 G/82
E/38 G/82 U E/75 G/15, S/30-170 G/54-95
G/175
G/38
--
G/65-95
Detergent Solution
--
G/82
E/82
--
--
Dichloroethane (Ethylene Dichloride) Diesel Fuel Dimethyl Ether Dimethylamine Dioxin Dipentane Diphenyl Diphenyl Oxide Esters (general) Ethane Ethers (general) Ethylene Ethylene Chloride Ethylene Diamine Ethylene Glycol Ethylene Oxide Fatty Acid Ferric Chloride
G/38
G/95
G/204
G/40
E/93
G/93 --G/38 -G/204 G/15
E/30 G/95 G/116 G/95 -G/95 G/26
E/30 G/95 -G/95 G/60 G/95 G/26
E/30 --G/175 -G/71 G/15
-G/95 -G/95 -G/95 G/65
--
--
G/204
--
--
G/93 G/93
-E/93
E/26 E/93
G/95 G/30
-G/30
G/65
G/95
G/95
G/95
G/95
G/26
G/26
G/204
G/26
--
G/38
G/95
G/170
E/38
G/95
G/204 U U
G/95 G/138 U
G/204 E/204 U
Ferric Nitrate U (SAT) Ferric Sulphate U
--
G/65
E/95 E/204 U; Titanium E/149 --
G/26 E/204 U; Tantalum E/149 U
G/26
E/93
G/26
Fish Oil Flue Gas Fluorine Gas (DRY) Fluorine Gas (MOIST.)
G/65 G/65 E/204; G/204-240 U; HastelloyC/C-270 E/293
G/65 G/65 E/216
U; NI-Resist G/230 --E/204 G/204-240 U
G/65 G/65 S/15 U
U
G/65 G/65 E/293 U;
Freon F –11 & F-12, F-22
U
G/30; Bronze G/210
G/204
G/26
E/204;
Freon F-21 & F-113
--
--; -Copper G/65
--
G/170
--; Bronze G/65 G/170
Fruit Juice Fuel Gas Fuel Oil Gas (Natural) Gas (Manufactured)
U
G/38
G/93 G/38 G/40
G/70 G/175 G/38
G/60 G/38 G/38
G/82 G/38 E/38
G/30
G/38
G/38;
G/38
G/120 G/38 G/38 Bronze G/175 G/30 NI-Resist E/204 G/130
Gasoline (Leaded)
G/38
Gasoline (Refined) Gasoline (Sour) Gasoline (Unleaded) Gelatin Gin Glaubar’s Salt Glycerine Glycolic Acid Glycol Green Liquor Heptanes Hexane Hydrochloric Acid (Dilute)
G/93
G/95
G/38
G/175
G/26
G/26
U
U
G/175
G/26
G/26
G/95
G/38
U --G/40 U G/26 G/204 G/175 G/175 U
G/65 G/93 -E/130 G/95 G/38 -G/120 G/116 U; Tantalum/149
G/165 G/93 G/26 E/95 G/175 G/26 -G/180 G/116 U
G/165 --E/95 E/175 G/38 -G/93 G/38 G/26
Hydrochloric Acid 20%
U
Hydrochloric Acid 50%
U
U
U
Hydrochloric
U
U; U Tantalum E/149 U; U Tantalum E/149 U; Tantalum U
G/82 --G/149 G/26 G/26 -G/26 G/26 U; HastelloyB/B-2 G/93 U
U
U
E/38
G/20
Acid Fume Hydrofluoric Acid (Dilute) DO 50%
U
E/38 U
U
U
E/204
U
U
U
U
G/71204
DO 100% DO Vapour Hydrogen Hydrogen Chloride Gas (DRY) DO (WET) Iodine
G/49 -E/293 G/38
U U E/293 E/293
G/26 U E/293 E/293
U U E/293 U
G/95 E/95 -E/204
E/204 U
E/204 U
U E/26
E/260 E/26
Iodine (10%) Solution
U
U
U
U
DO (SAT)
U
E/204 U; Hastelloy C/C 270 G/82 U; Hastelloy C/C 270 G/82 U; Hastelloy C/C 276 G/85 -G/65 G/38 G/204 G/26 G/120
U
U
U
G/65 G/65 G/204 G/204 G/65 G/130
--G/75 G/75 U G/38
G/65 G/65 G/38 G/95 G/65 G/38
G/95
E/40, G/40-95 E/40, G/40-95 G/149
G/26
U
G/26
U
G/38
U
G/38; Bronze G/175
G/30
G/38
--
G/95 G/95 --
G/95 G/95 G/65
U U --
G/95 G/95 G/65
Isobutene G/65 Isooctane G/65 Jet Fuel G/75 Kerosene G/175 Ketchup U Ketenes, G/93 General Lactic Acid U 5% DO 25% U DO U (Concentrated) Lard Oil S/38
LPG Lube Oil Lead Acetate Lead Sulphate Lime Slurry
U U G/65
G/49 G/18
Linseed Oil Lubricating Oil Machine Oil Magnesium Carbonate
G/30 G/65
G/95 G/65
G/95 G/65
G/26 G/65
G/38 G/38
G/95 --
G/95 G/95
G/95 G/95
-G/30
-G/30
Mercuric Chloride Mercury Methane Methanol Methyl Acetate Methyl Acetone Methyl Alcohol Methyl Amine Methyl Chloroform Milk Mineral Oil Molasses Motor Oil Naphtha Naphthalene Nickel Chloride Nickel Salt
U
U
G/175
U
U
G/293 G/293
E/293 E/293
E/293 E/293
U E/93
G/293 E/95
S/65 G/65
G/104 E/26
G/104 G/65
G/26 E/26
E/26 G/65
G/95
G/120
G/175
G/65
G/95
E/26 S/26
G/50 G/30
G/65 --
G/26 --
U --
G/71 G/38 G/38 G/120 G/30 G/82 U
E/95 E/30 E/95 G/120 G/120 E/204 G/95
E/175 G/175 E/175 G/120 G/95 E/204 G/95
E/93 G/75 G/26 -G/82 G/95 U
S/30 E/38 G/38 E/30 G/49 G/95 G/95
U
HastelloyG/26 C/C 276 G/149 E/95 E/95
U
--
U
U
E26, G/26- E/30,G/3093 93 E/26 E/40 E/50 E/50 E/293 E/293 G/65 G/65 G/65 G/120 G/140 E/140 G/65 G/65 U G/175
U
U
E/30 E/50 G/30 G/65 G/65 G/26 E/26 S90
U U -G/65 -G204 E65 G/95
Nitric Acid U 5% DO 50% U DO 100% DO Fumes Nitrogen Octane Oil and Fats Oleic Acid Olive Oil Oxalic Acid
U U E/15 G/65 G/65 G/26 G/65 U
5% DO 50% DO (SAT)
U U
U U
G/175 U
Oxygen Oxygen Gas
G/65 --
G/30 TantalumE/149
Ozone Paraffin Peanut Oil
S/40 G/38 --
Pentane Petrolatum Petroleum Oil (Refined) Petroleum Oil (Sour) Phenol (Carbolic Acid) Phosphoric Acid (5%) DO (10%)
G/65 S/38 -
DO (25-50%)
U
Phosphorus Polyvinyl Acetate Potassium Bisulphate Potassium Carbonate 50% Potassium Chloride (30%) Potassium Cyanide (30%) Potassium Hydroxide 27%
G/65 G/30
G/175 --
S/85 G/26,S/2650 G/26 --
G/38 G/130 Bronze G/175 G/65 G/38 G/26
G/175 G/130 G/65
G/40 G/130 --
G/38 G/65 --
G/65 G/171 G/26
G/65 G/49 G/30
G/65 G/38 G/30
G/26
G/30
U
G/95
Tantalum E/149 E/293
E/293
E/65
E/293
--
E/85
E/95
U
E/15
U
E/85
S/38
S/15
U
S/26
---
E/85; S/85-95 U/65; G/65- G/93 85 E/49 E/49 E/82 E/82
G/30 --
E/49 --
U
G/26
G/65
--
U
G/95
E/95
E/95
U
G/95
G/95
E/95
E/175
U
G/95
G/95
G/95
E/175
U
E/65
G/93
G/95
G/175
U
E95
--
G/26 --
DO 50% Potassium Iodide (70%) Potassium 20% Permanganate Potassium Sulphate (10%)
G/30 S/38
G/95 G/95
G/150 G/95
U S/38
E/95 G/95
G/26
G/95
G/175
G/95
G/95
G/95
E/95
E/175
E/95
E/95
DO Pure Propylene Glycol Propylene Oxide Pyridine Propylene Dichloride Propane Quinine Bisulphate Quinine Sulphate Quinine Reactor Effluent Silicon Oil Silver Chloride Silver Cyanide Silver Nitrate Soaps Soap Solution (5%) Soap Solution Sodium Acetate Sodium Benzoate Sodium 20% Bicarbonate Sodium Bicarbonate (Neutral)
-G/110
G/26 G/30
G/26 G/95
-G/75
G/26 G/30
G/65
G/60
G/60
--
--
G/49 G/65
G/95 G/120
G/175 --
G/175 --
G/95 G/65
G/175 --
G/82 G/15
G/165 G/15
E/30 --
E/30 E/15
--
--
--
--
E/15
--
--
G/65
--
--
G/38 U
G/38 U
G/38 U
G/38 U
-G/26
-U S/15 G/65
E/30 G/293 G/30 G/65
E/30 G/293 G/149 G/65
U U G/149 G/40
G/30 U G/30
G/75 U
G/30 G/293
G/30 G/293
G/149 E/30
G/38 G/95
--
--
--
G/38
G/38
S/38
E/110
E/175
G/65
E/95
--
G/30
G/38
G/30
--
Sodium 30% Chloride (Salt) Sodium Carbonate Sodium Chlorate Sodium Citrate Sodium Cyanide Sodium Hydroxide 10% (Caustic Soda) Caustic Soda 15% Caustic Soda 30% Caustic Soda 50%
G/71
G/95
G/175
U
E/30
G/49
G/95
G/175
U
E/95
S/26
G/95
G/95
G/204
E/95
-G/38
G/30 E/95
G/95 E/175
U U
G/15 U
G/95
E/95
E/175
U
E/95
G/95
E/65,G/6595 E/75
E65, G/65-149 E/75
U
E/175
U
E/75
E/75,G/7595
E/75,G/75- U 95
G/30
G/175
U
E/93, G/93149 G/175
FEP E/204 G/30
-G/30
-U
-G/30
G/95
G/175
G/95
G/95
G/95
G/95
U
G/95
G/95
G/95
U
G/95
G/95 GG/95
G/95 G/170
U E/30
G/95 G/95
E/204
E/204
E/95
G/95
Hastelloy C/C-270 E/65 G/38 G/293
--
--
--
G/65 G/293
G/75 G/95
G/65 E/293
G/95 S/38
Caustic Soda S/140 (Conc.) Sodium Iodide G/26 Sodium Lactate FEP E/204 Sodium 10% G/30 Peroxide Sodium -(Acid) Phosphate Sodium G/65 (Alkaline) Phosphate DO (Neutral) -Sodium G/95 Silicate Sodium G/65 Sulphate Sour Crude Oil --
Soybean Oil Steam (LP)
G/40 G/293
Steam (MP) Steam (HP) Styrene
G/293 G/293 E/50
G/293 G/165 G/26
G/293 G/293 G/55
-U G/26
E/293 U G/55
Sulfonated Detergent
--
--
--
--
Sulphur
U
Hastelloy C/C-276 E/55 E/293
E/293
E/293
E/85, G/85195
Sulphur Chloride
U
G/95; NickelE/293 TantalumG/30 G/293
G/40
S/30
S/30
--
--
--
G/293
G/149
G/82
G/293 U
U U
U S/26
U
U
S/26
U
U
G/30
U
U
G/30
G/95
U
U
G/40
U U; Hastelloy G/G-3 G/120 U; Incolloy 825 G/110 U; Hastelloy B/B-2 E/110 U; TantalumG/149 S/30; Hastelloy B/B-2 G/95 G/26
G/95
U
U
--
E/30
E/30
E/30
U
U -G/93 ---
G/95 G/50 GGG/93 E/204 U; Hastelloy C/C276 G/110
G/95 G/50 G/93 E/204 G/65
U E/26 G/93 ---
G/95 -G/93 ---
Sulphur -Dichloride Sulphur Oxide E/55, DRY G/55293 DO (WET) U Sulphuric Acid U 10% Sulphuric Acid U 30% Sulphuric Acid U 50% Sulphuric Acid U 70% Sulphuric Acid S/38 98% Sulphuric Acid 100% Sulphuric Acid (Fumes) Tannic Acid Tanning Liquor Tar Tartaric Acid Tin Chloride
Toluene (Toluol) Tomato Juice Transformer Oil Trim Ethyl Propane Turpentine Urea 50% Uric Acid (Conc.) Urine Vegetable Oil Water
E/175
E/95
E/175
E/95
E/95
S/40 G/26
G/30 G/30
G/120 30
G/40 G/26
G/30 G/30
--
--
--
--
--
G/26 G/30 --
E/93 G/95 E/30
E/93 G/95 E/30
G/82 G/95 U
E/40 G/26 E/30
G/38 G/71 G/65
E/38 G/95 G/95
E/38 G/95 G/95
-G/71 G/95
-G/72 G/95
Table : Re comme nde d Piping Mate rials and Corrosion Allowance Fluid Service Acetate solvent Acetic acid Acetic anhydride
Corrosion Allowance (mm) 1.5 Nil Nil Nil 3.0
Acetone Acetylene Acid mine Water Air (Plant air)
1.5 1.5 Nil 1.5
Air Instrument
1.5
Alcohol Aldehyde Alum (Aluminium Sulphate) Amine Ammonia Vapour
1.5 1.5 Nil
Ammonia Liquid
1.5
3.0 1.5
Recommended Piping Materials API 5l Gr B A312 Gr TP 304 A312 Gr TP 304 Aluminium API 5L Gr B with glass lining API 5L Gr B API 5L Gr B PVC IS 1239 Gr HVY, IS 3589 IS 1239 Gr Hvy (Galv.) API 5L Gr B API 5L Gr B A312 Gr TP 304 API 5L Gr B API 5L Gr B (max. 260 0C) API 5L Gr B (max.
Ammonia Chloride
1.5
Ammonium Hydroxide Ammonium Nitrite Ammonium Phosphate Ammonium Sulphate Amyl Acetate
Nil Nil Nil 1.5 1.5 1.5
Amyl Alcohol
Nil 1.5
Aniline or (Aniline oil)
Nil Nil
Aniline Dyes Aromatics Asphalt Barium Chloride Benzyl (high temp.) Benzyl (low temp.) Bitumen Boiler Feed Water Brine Caustic Soda
Nil 1.5 1.5 1.5 Nil 3.0 1.5 1.5 1.5 1.5 1.5
Caustic Solution Chemical Coke Cutting Water Corrosive Hydrocarbon Corrosive Sour Cooling Water
3.0 Nil 1.5 1.5 3.0 1.5
Corrosive Service
Process 3.0 Nil 3.0
260 0C) API 5L Gr B (in production) A312 Gr TP 304 A312 Gr TP 304 A312 Gr TP 304 API 5L Gr B API 5L Gr B API 5L Gr B (in production) A312 Gr TP 304 API 5L Gr B (in production) A312 Gr TP 304 A312 Gr TP 304, Monel A312 Gr TP 304 API 5L Gr B API 5L Gr B API 5L Gr B A312 Gr TP 304 A335 Gr P5 API 5L Gr B API 5L Gr B A106 Gr B API 5L Gr B API 5L Gr B, Max. 400 0C API 5L Gr B A312 Gr TP 304 API 5L Gr B API 5L Gr B API 5L Gr B IS 1239 / IS 3589 API 5L Gr B, Max. 260 0C API 5L Gr B, Max. 425 0C A312 Gr 316L Max. 425 0C A335 Gr P5 Max. 230 0C
Corrosion Inhibitor
1.5
API 5L Gr B
Corrosive Sour Service Coal Tar (Low Temp.) Coal Tar (High Temp.) Crude Oil
3.0 1.5 3.0 3.0
Demulsified Solution Diesel
1.5 1.5
API 5L Gr B API 5L Gr B A335 Gr P5 A335 Gr P5 Beyond 230 0 C API 5L Gr B API 5L Gr B, Max. 230 0 C A335 Gr P11 0 Beyond 230 C HDPE
3.0 Dilute Sulphuric Acid
Nil
D M Water
1.5 Nil Nil
Drinking Water Effluent Water Fuel Oil
Nil 3.0 3.0 1.5
Fuel Gas Fire Water
1.5 1.5
Flushing Oil
1.5 1.5
Gas Wash (Caustic) HCL Gas Hydrocarbon Corrosive)
Water 3.0 Nil (Non- 1.5 1.5
Hydrocarbon Corrosive)
(Mild 3.0 3.0
API 5L Gr B, Max. 260 0 C A312 Gr 304 API 5L Gr B, (Rubber Lined) IS 1239 / IS 3589 API 5L Gr B A335 Gr P11, Beyond 230 0 C API 5L Gr B, Max. 230 0 C API 5L Gr B, API 5L Gr B, Max 260 0 C IS 1239/IS 3589 API 5L Gr B, Max. 260 0 C API 5L Gr B HDPE API 5L Gr B, Max. 425 0 C A335 Gr P5, 0 Beyond 425 C API 5L Gr B, Max. 425 0C A335 Gr P5, Beyond 425 0C
Hydrocarbon (Corrosive)
Nil 1.0
A312 Gr TP 304 A312 Gr TP 316L / Gr 3210
3.0
API 5L Gr B, Max. 425 0C A335 Gr P5, 0 Beyond 425 C A312 Gr TP 304 A312 Gr TP 316L / Gr 3210 A106 Gr B A106 Gr B A106 Gr B A335 Gr P11/P22 A312 Gr TP 304 / TP 321H
3.0 Nil 1.0 H2S Hydrogen and (Toxic) Hydrogen Temp.) & (High Temp.)
4.5 4.5 3.0 (Low 1.5 Nil
Instrument Air Liquid Sulphur
Nil 3.0
Lime Sulphur Linseed Oil LPG Lubricant Oil Lye Magnesium Chloride Magnesium Sulphate
1.5 1.5 1.5 1.5 1.5 1.5 4.5 Nil Nil Nil Nil 1.5 1.5 1.5
Mercuric Chloride Mercury Methane Methanol/Methyl Alcohol Do Product) Milk Mine Water Milk of Lime Mixed Acid
IS 1239 (Galv.) A106 Gr B, Max. 375 0C API 5L Gr B API 5L Gr B API 5L Gr B API 5L Gr B API 5L Gr B API 5L Gr B API 5L Gr B PVC A312 Gr TP 304 Monel Hastelloy API 5L Gr B API 5L Gr B API 5L Gr B
(Pure Nil
A312 Gr TP 304
Nil Nil 3.0 (Low Nil
A312 Gr TP 304 PVC API 5L Gr B A312 Gr TP 304
Temp.) (High Temp.) Molasses Temp.) (High Temp.)
Nil (Low Nil
Nil Naphtha Temp.) (Low Temp.) Natural Gas Neon Nickel Chloride Nickel Sulphate Nitre Cake Temp.) (Low Temp.) Nitric Acid
(Passivated) Tantalum PVC
(High 3.0
API 5L Gr (Teflon Coated) A335 Gr P5
1.5 1.5 1.5 Nil Nil Nil Nil (High Nil
API 5L Gr B API 5L Gr B API 5L Gr B Monel A312 Gr TP 304 Monel A312 Gr TP 304 PVC
Nil Nil
Nil Nitrogen 1.5 Non-Corrosive Service 1.5 Nitrobenzene 1.5 Oil of Mir bane 1.5 Oil of Vitriol (Sulphuric 1.5 Acid) Oxalic Acid Nil Nil Oleum Sprits Oxygen 1.5 Nil Phosphate Solution Nil Polished Water Nil (150 psi) Nil Pantene 1.5 Petroleum Oils & 1.5 Solvent Phenol 4.5 Nil
B
Red Brass API 5L Gr B (Glass Lined) A312 Gr TP 304 API 5L Gr B API 5L Gr B API 5L Gr B API 5L Gr B API 5L Gr B Monel Red Brass API 5L Gr B API 5L Gr B A312 Gr TP 304 L A312 Gr TP 304 HDPE Max. Temp. 1500C Monel API 5L Gr B API 5L Gr B API 5L Gr B A312 Gr TP 304 L
Phosphoric Acid Ophthalmic Acid Pickling Acid Picric Acid
Nil Nil 2.0 4.5 Nil Nil
Potassium Carbonate
Nil 1.5 Nil
Potassium Chloride Potassium Hydrochloride
Nil 1.5 Nil
Potassium Nitrite Potassium Sulphate Potassium Sulphide
1.5 1.5 1.0 1.5 Propane 1.5 3.0 Pyridine 1.5 RCO (Temp.) 3.0 Raw Water (Max. Temp 1.5 2600C) Reactor Effluent 3.0 Steam NIBR 1.5 (LP) NIBR (LP) NIBR 1.5 (Tracing) IBR IBR IBR IBR
(LP) (MP) (HP) (HP)
1.5 1.5 1.0 Nil Do Do Do
Sulphuric Acid (70 to 1.5 90% Conc.)
A312 Gr TP 304 L PVC A312 Gr TP 304 API 5L Gr B PVC API 5L Gr B (Glass Lined) A312 Gr TP 304 API 5L Gr B PVC Conc.<75% (Low Temp.) A312 Gr TP 304 API 5L Gr B PVC Conc.<75% (Low Temp.) API 5L Gr B API 5L Gr B A 316 L API 5L Gr B API 5L Gr B A335 Gr P5 API 5L Gr B A335 Gr P5 API 5L Gr B Max Temp 2600 C A335 Gr P11 API 5L Gr B Max Temp 2600 C API 5L Gr B Max Temp 2600 C A 106 Gr B A 106 Gr B Max Temp 4000 C A 335 Gr P11 Above 400/5500 C A 312 TP 321H Above 5500 C Do Do do API 5L Gr B
Sulphuric Acid (Up to Nil 60% Conc.) Sea Water Nil Nil Sewage 1.5 Soap Solution Soda Ash Sodium Bicarbonate Sodium Carbonate
Nil 1.5 Nil Nil 1.5 Nil 1.5 Nil 1.5 1.5 1.5 Nil
Sodium Nitrate Sodium Nitrite Sodium Peroxide Sodium Phosphate Sodium Phosphate 1.5 (basic) Sodium Chloride 1.0 Nil Sweet Gas 1.5 Sodium Silicate 1.5 Sodium Sulphate 1.5 Sour Flare 3.0 Sodium Sulphide 1.0 Soybean Oil Nil Sulphur 1.5 Sulphur Vapour 3.0 Sulphur Chloride (Dry 3.0 Gas) Sour Water 3.0 Sour Gas
4.5
Suffer Trioxide Slops Service Water Sour Water
1.5 1.5 1.5 4.5
HDPE HDPE Cupronickel Cast Iron RCC Pipe API 5L Gr B HDPE HDPE API 5L Gr B HDPE API 5L Gr B HDPE API 5L Gr B API 5L Gr B API 5L Gr B A312 Gr TP 304L API 5L Gr B A312 Gr TP 304L PVC API 5L Gr B API 5L Gr B API 5L Gr B API 5L Gr B A312 Gr TP 316L A312 Gr TP 304L API 5L Gr B API 5L Gr B (Max. Temp. 3750C) API 5L Gr B API 5L Gr B (Temp. 4000C) API 5L Gr B (Temp. 4000C) API 5L Gr B API 5L Gr B IS 1239/ IS 3589 API 5L Gr B Max.
Tar Tartaric Acid Titanium Chloride Trisodium Phosphate Turpentine (Product) (Purified Product) Varnish Product)
Nil
Monel
(Rough 1.5 Nil (Purified
Product) Vegetable Oil Vinegar VAC Vacuum Residue VB TAR Whisky Wine Wash Water Xylem Temp.) Temp.) Zinc Chloride Zinc Sulphate
1.5 Nil Nil 1.5 1.5
Temp. 4000C API 5L Gr B A312 Gr TP 304L Monel API 5L Gr B API 5L Gr B
API 5L Gr B A312 Gr TP 304
Nil Nil 1.5 3.0 3.0 Nil Nil 3.0 (Low 1.5
A312 Gr TP 304L Monel / Inconel API 5L Gr B A335 Gr P5 A335 Gr P5 Copper / Brass A312 Gr TP 304L API 5L Gr B API 5L Gr B
(High 3.0
A335 Gr P5
3.0.5 1.0
API 5L Gr B A312 Gr TP 316L
4 Piping Design
4.1
General
Design refers to a plan or convention for the construction of an object or a system. Design defines the specifications, plans, parameters, costs, activities, processes and how and what to do within legal, political, social, environmental, safety and economic constraints in achieving that objective. Design is making a specification of an object, intended to accomplish goals, in a particular environment, using a set of primitive components, satisfying a set of requirements and subject to constraints. Design is a roadmap or a strategic approach for someone to achieve a unique expectation. The design includes a discrete sequence of stages. Process piping systems include pipe and appurtenances used to transport fluids. Separate guidance has been provided for plumbing, potable water, sewage, storm drainage, fuel and lubricant systems. The design analysis includes the design of the process piping systems. The design criteria include Engineering, System Description, Specifications, Drawings, Drawing Requirements, Process Flow Diagram (PFD) Content, Piping and Instrumentation Diagram (P&ID) Content, Piping Sketches, Service Conditions, Applicable Codes and Standards, Environmental requirements, and other parameters, which may constrain the work. However piping design can be understood in better ways by following main aspects of design strategy: Design conditions; Design Criteria’s; Fluid service conditions; Selection of materials; Selection of Valve, Flange, Fitting & Other Piping Components; Piping Sizing Criteria; Design Considerations for Particular Piping System & Instruments; Piping flexibility and Supports; Design of Piping Joints; Design Engineering and Limitations; and Plant Layout. Applicable Codes and Standards: Piping codes provide required design criteria. These criteria are rules and regulations to follow when designing a piping system. The following piping codes include design criteria, allowable stresses and stress limits; allowable dead loads and load limits; allowable live loads and load limits; materials; sizing; minimum wall thickness; maximum deflection; seismic loads; and thermal expansion. ASME SEC-I : Rule for construction of Power Boiler ASME SEC-IV : Rules for Construction of Heating Boilers ASME SEC-VIII: Rules for Construction of Unfired Pressure Vessels ANSI B31.1 : Code for general pressures piping ANSI B31.2 : Industrial Gas and Air Piping ANSI B31.3 : Code for petroleum refinery piping ANSI B31.4 : Code for Liquid petroleum transportation piping system ANSI B31.5 : Refrigeration Piping. ANSI B31.6 : Chemical Industry Process Piping ANSI B31.8 : Gas Transmission and Distribution Piping Systems. ASME B31.9 : Working Pressure and Temperature Limits ANSI B16 : Standards of Pipes and Fittings ANSI B31.4 : Nuclear Piping API RP14E : Recommended practice for offshore piping. API RP14C : Recommended practices for Safety Devices for process components. API RP520 : Recommended practice for design and installation of Pressure Relieving n Refineries, Part-I and Part-II.
API 1102
:
API 1104
:
API 1105
:
API 1107
:
MSS-SP-58 MSS SP-69 NACE MR-01-75:
Recommended practice for liquid petroleum crosscountry pipeline. Specification for welding of cross-country pipeline and related facilities Bulletin on construction practices for oil and its producer’s pipelines Recommended practice for maintenance of welding of pipelines : Material and Design of Pipe Hangers and Supports : Selection and application of pipe hangers and supports Sulphide Stress Corrosion Cracking Resistant Metallic Material. NACE MR-01-77: Testing of Metals for Resistance to Sulphide Stress Cracking. NFC : National Fire Code Volume 6 for Sprinklers, Fire Pumps, and Water Tank. NFC : National Fire Code Volume 8 for Portable and Manual Fire Control Equipment. IBR : Indian Boilers & Regulation
4.2
Design Requirements
The bases of design are the physical and material parameters such as loading and service conditions and environmental factors that are considered in the detailed design of a liquid process piping system to ensure a reasonable life cycle. The bases of design must be developed in order to perform design calculations and prepare drawings. a. Pre-design Surveys: Pre-design surveys are recommended for the design of process piping for new processes and are a necessity for renovation or expansion of existing processes. A site visit provides an overview of the project. Design requirements are obtained from the clients. An overall sense of the project is acquired, and an understanding of the aesthetics that may be involved is developed. For an existing facility, a Pre-design survey can be used to evaluate piping material compatibility, confirm as-built drawings, establish connections, and develop requirements for aesthetics. b. Soil Investigation: Soil conditions play a major role in the selection of piping systems. Soils, which contain organic or carbonaceous matter such as coke, coal, or cinders, or soils contaminated with acid wastes, are highly corrosive. These conditions impact ferrous metals more than nonferrous metals. For normally acceptable metals, soil variations may be significant. Buried pipes corrode faster at the junction line of dissimilar soils. In fact, placing a metal pipe where it crosses dissimilar soils may generate electric potentials up to one (1) volt. Civil Engineering addresses requirements for pre-design surveys and soils investigation sampling that may be necessary to design cathode protection systems. c. Service Conditions: The piping system is designed to accommodate all combinations of loading situations (pressure changes, temperature changes, thermal expansion/contraction and other forces or moments) that may occur simultaneously. These combinations are referred to as the service conditions of the piping. Service conditions are used to set design stress limits and may be defined or specified by code, or are determined based on the system description, site survey, and other design bases. d. Environmental Factors: The potential for damage due to corrosion must be addressed in the design of process piping. Two instances of temperature changes must be considered as a minimum. First, there are diurnal and seasonal changes. Second, thermal expansion where elevated liquid temperatures are used must be accommodated. Corrosion occurs in metallic piping, which is the problems that can result from corrosion, and how appropriate material choices can be made to minimize corrosion impacts. e. Force Measures: Design concerns for the effects of physically damaging phenomena, such as, fires, spills, power outages, impacts/collisions, and breakdown or failure of associated equipment and natural phenomena like, seismic occurrences, lightning strikes, wind, and floods. Risk is a combination of probability and consequence. There are infinite possibilities and all scenarios will not be covered by direct reference to codes. f. Safety Provisions: Safety provisions as required by the Safety and Health Requirements Manual, Safety standards, codes, and other manuals are required to be taken. Requirements of the Occupational Safety and Health Administration (OSHA) are minimum design constraints in process piping design. g. System Descriptions: System descriptions provide the functions and major features of each major system and may require inputs from mechanical, electrical and process control disciplines. The system description contains system design bases, operating modes and control concepts, and both
system and component performance ratings. System descriptions provide information to develop process flow diagrams (PFDs), piping and instrumentation diagrams (P&IDs), and approvals necessary to proceed. h. Specifications: Specification is a plan from which the design object is composed. Piping specifications define material, fabrication, installation and service performance requirements. i. Process Flow Diagram (PFD): The Process Flow Diagram (PFD), a schematic illustration of the system shows the relationships between the major components in the system. PFD also tabulate process design values for the components in different operating modes, typical minimum, normal and maximum.
Figure 1: Process Flow Diagram (PFD) A PFD does not show minor components, piping systems, piping ratings and designations. PFD includes, Process Piping, Major equipment symbols, names and identification numbers, Control, valves and valves that affect operation of the system, Interconnection with other systems, Major bypass and recirculation lines, System ratings and operational values as minimum, normal and maximum flow and, temperature and pressure Composition of fluids. Process Flow Diagrams does not include pipe class, pipe line numbers, minor bypass lines, isolation and shutoff valves, maintenance vents and drains, relief and safety valve, code class information and seismic class information. This figure depicts a small and simplified PFD: j. Piping and Instrumentation Diagram (P&ID) Content: P&IDs schematically illustrate the functional relationship of piping, instrumentation and system equipment components. P&IDs show all of the piping, including the intended physical sequence of branches, reducers, and valves, etc.; equipment; instrumentation and control interlocks. The P&IDs are used to operate the process systems. k. Piping and Instrumentation Diagram (P & ID): P & IDs schematically illustrate the functional relationship of piping, instrumentation, and system equipment components. P & IDs show all of the piping, including the intended physical sequence of branches, reducers, and valves, etc.; equipment; instrumentation and control interlocks. The P & IDs are used to operate the process systems.
Following is the lists of the typical items contained on a P & ID, which is: Mechanical Equipment, Names, and Numbers; all Valves and Identification; Instrumentation and Designations; All Process Piping, Sizes, and Identification; Miscellaneous Appurtenances including Lines, Reducers and
Increasers, Vents, Drains, Special Fittings, Sampling; Direction of Flow; Class Change; Interconnections; and Control Inputs/Outputs and Interlocks. This figure depicts a very small and simplified P & ID:
4.3
Design Conditions
Design conditions for specific process applications should consider pressure, temperature, and fluid service. The Design Conditions include the following, in general but not limited. After the piping system’s functions, drawings, service conditions, and materials of construction the next step is to finalize the system operational pressures and temperatures. Engineers may consider more conditions or factors as per relevant Standard Design Codes and his experience, if any, than the listed below:
(A) DESIGN
PRESSURE : The pressure in a fluid is defined as "the normal force per unit area exerted on an imaginary or real plane surface in a fluid or a gas". The equation for pressure can expressed as: p=F/A -------------------------------------------------------------------------- (1) Where, p = pressure [lb/in2 (psi) or lb/ft2 (psf), N/m2 or kg/ms2 (Pa)]; F = force [1), N]; and A = area [in2 or ft2, m2] Absolute Pressure: The absolute pressure - pabs - is measured relative to the absolute zero pressure - the pressure that would occur at absolute vacuum. All calculation involving the gas laws requires pressure (and temperature) to be in absolute units. Gauge Pressure: A gauge is often used to measure the pressure difference between a system and the surrounding atmosphere. This pressure is often called the gauge pressure and can be expressed as, pg = ps - patm --------------------------------------------------------------------- (2) Where, pg = gauge pressure, ps = system pressure, patm = atmospheric pressure Atmospheric Pressure: Atmospheric pressure is pressure in the surrounding air at - or "close" to the surface of the earth. The atmospheric pressure varies with temperature and altitude above sea level. The system operating pressure, up to this point, has been addressed from a process requirement viewpoint to ensure proper operation of the system as a whole. In order to select the design pressure, it is necessary to have a full understanding and identifying the maximum steady state pressure, and determining and allowing for pressure transients of all operating processes piping system. a. Maximum Pressure: Pipe and Piping components shall be designed for an internal coincident maximum pressure and temperature expected in normal operation. This condition results in the greatest pipe thickness. The system must also be evaluated and designed for the maximum external differential pressure conditions. ASME B31.3 governs the following pressure and temperature rating for the metal pipe to be used: (1) Listed components having established rating utilize the materials as listed in Table 326.1 of ASME B31.3. (2) Listed components having established rating utilize the components of the same materials with the same allowable stress as material specified in the codes and standards contained in Table 326.1 of ASME B31.3. (3) Unlisted components, i.e. components that are not listed in ASME B31.3 but conform to other published standards, may be utilized if the requirements of the published standard are compatible to ASME B31.3 requirements and if the pressure design satisfies the ASME B31.3 pressure design of components. b. Transients Pressure: Most design codes provide allowances for short duration transient conditions, which do not increase the design pressure and temperature. Before finalizing the system
design pressure and temperature, allowances for transient conditions are reviewed and the anticipated conditions in the code are fully evaluated. Pressure and temperature variations state that occasional variations of pressure or temperature, or both, above operating levels are characteristic of certain services. The most severe conditions of coincident pressure and temperature during the variation shall be used to determine the design conditions unless all of the following criteria are met. (a) The piping system shall have no pressure containing components of cast iron or other non-ductile metal. (b) Nominal pressure stresses shall not exceed the yield strength at temperature (see Para. 302.3 of Code [ASME B31.3] and Sy data in [ASME] BPV Code, Section II, Part D, and Table Y-1). (c) Combined longitudinal stress shall not exceed the limits established in paragraph 302.3.6 [of ASME B31.3]. (d) The total number of pressure-temperature variations above the design conditions shall not exceed 1000 during the life of the piping system. (e) In no case shall the increased pressure exceed the test pressure used under Para 345 of ASME B31.3 for the piping system. (f) Occasional variations above design conditions shall remain within one of the following limits for pressure design. 1) Subject to the owner's approval, it is permissible to exceed the pressure rating or the allowable stress for pressure design at the temperature of the increased condition by not more than: 33% for no more than 10 hour at any one time and no more than 100 hour per year; or 20% for no more than 50 hour at any one time and no more than 500 hour per year. The effects of such variations shall be determined by the designer to be safe over the service life of the piping system by methods acceptable to the owner. (See Appendix V of ASME B31.3) 2) When the variation is self-limiting and lasts no more than 50 hour at any one time and not more than 500 hour/year, it is permissible to exceed the pressure rating or the allowable stress for pressure design at the temperature of the increased condition by not more than 20%. (g) The combined effects of the sustained and cyclic variations on the serviceability of all components in the system shall have been evaluated. (h) Temperature variations below the minimum temperature as shown in Appendix “A” of ASME B31.3 are not permitted unless the requirements of Paragraph 323.2.2 of ASME B31.3 are met for the lowest temperature during the variation. (i) The application of pressures exceeding pressure-temperature ratings of valves may under certain conditions cause loss of seat tightness or difficulty of operation. The differential pressure on the valve closure element should not exceed the maximum differential pressure rating established by the valve manufacturer. Such applications are the owner's responsibility.” (j) The maximum pressure rating of the pipe is calculated using the following equation: 2 S E (tm + A) Pmax = Do x 2 y (tm + A)
Where: Pmax = maximum allowable pressure, MPa (psig); S = code allowable stress, MPa (psi); E = joint efficiency; tm = pipe wall thickness, mm (in); A = corrosion allowance, mm (in); Do = outside diameter of pipe, mm (in); y = temperature-based coefficient, see ASME B31.1, for cast iron, non-ferrous metals, and for ferric steels, austenitic steels and Ni alloys less than 4820C (9000F), y = 0.4. (k) The design pressure is also arrived on the basis of the following considerations: (i) The minimum positive design pressure shall be normally 3.5 kg/cm2. (ii) The discharge piping of a centrifugal pump, not protected by safety valve, should be designed for 1.2 times the max. Pump Differential plus the max. Suction Pressure of the pump.
(B) DESIGN
TEMPERATURE : The design temperature in a piping system is the maximum temperature of component expected in the service during the life of the piping system. It is the temperature at which, under the coincident pressure, the greatest thickness or highest component rating is required. This is the temperature of all the fluid, atmosphere, and solar radiation, heating and cooling medium and other coincidental conditions. Low temperature less than –29 0 C needs special design requirements and material qualification requirement. For detail governing rules, please refer the design Standards & Codes for piping components design. Piping components shall be designed for the temperature representing the most severe conditions described as follows: The design temperature of non-insulated pipe may be the metal temperature rather than the fluid temperature. The design temperature of the steam traced piping may be the fluid temperature or 20 0 F below saturation temperature of tracing steam whichever is greater. The design temperature of Low Temperature piping with a fluid temperature below –20 0 F may be the normal fluid operating temperature. For fluid temperatures below 65 0C (150 0F), the metal design temperature of the pipe and components shall be taken as the fluid temperature. For fluid temperatures above 65 0C (150 0F), the metal design temperature of un-insulated pipe and components shall be taken as 95% of the fluid temperature, except flanges, lap joint flanges and bolting shall be 90%, 85% and 80% of the fluid temperature, respectively. For insulated pipe, the metal design temperature of the pipe shall be taken as the fluid temperature unless calculations, testing, or experience based on actual field measurements can support the use of other temperatures. For insulated and heat traced pipe, the effect of the heat tracing shall be included in the determination of the metal design temperature. In addition to the impact of elevated temperatures on the internal pressure, the impact of cooling of gases or vapours resulting in vacuum conditions in the piping system must be evaluated.
(C) AMBIENT F LUCTUATING E FFECTS : (i) Ambient Cooling Effect on Pressure: Sometimes, the pressure in the pipe is suddenly and sufficiently reduces due to cooling of a gas or vapour in the pipe. This creates an internal vacuum. So a pipe may be designed in such a way, considering the external pressure (vacuum inside) so that it is capable to withstand the external pressure at lower temperature. Some arrangement like automatic
vent opening or breathing (breather valve) may be provided on pipe to break the vacuum. (ii) Ambient Heating Effect on Fluid expansion: Sometime the pressure in the pipe is suddenly and sufficiently increased due to sudden heating or boiling of a fluid in the pipe. Pipe may be designed strong to withstand the increase in pressure caused by heating and boiling of the fluid. The set pressure of the relief valve may not exceed the lesser of the system test pressure or 112% of design pressure (refer 322.6.3(b) (2) of ANSI B31.3. (iii) Ambient Icing Effects: When you design a piping system to handle fluid below 0 0C (32 0F), you should consider the possibility of moisture condensation and building of ice. You should take a precautionary measure to avoid ice building on moving parts of shut off valves, control valves, pressure relief valves etc. and resultant malfunction of the above valves. (iv) Ambient Low Temperature: When a piping system is designed in low ambient temperature area, design consideration may be low ambient temperature conditions prevailing in the area and accordingly displacement stress analysis shall be done. (v) Ambient Corrosion Effects: While designing a piping system, the consideration for corrosion allowance should be given while calculating the thickness of the pipe. However, all Carbon Steel piping should be protected with a coating (painting) system, which has been proven acceptable in a normal or marine environment by prior performance, or by suitable tests. Among the generic types, currently in use are the following: Wash primer-vinyl or chlorinated rubber system; Inhibited epoxy primer-epoxy system; Zinc rich epoxy primer-epoxy system; Zinc silicate inorganic primer-vinyl, or epoxy system.
(D)
EFFECTS : (i) Impact effects: Sometimes in vertical pipe or inclined pipe, when we handle fluids at a temperature of its boiling point or near to its boiling point, then a rapid evolution of vapour takes place inside the pipe. Due to this a pressure surge is generated which may cause destruction to the piping. This is called Geysering. This causes impact on the pipe. There are many other factors external or internal, which cause impact on the pipe, such as change in flow rate, hydraulic shock, water hammer, liquid or solid slugging, and flashing etc. While designing a piping system, the impact effect may be taken into account. (ii) Wind Effects: Some times, in certain area, the wind load and wind velocity is so high due to cyclone or low pressure in atmosphere, which affect the exposed piping. So the wind velocity/load effect shall be taken into consideration while designing piping exposed to atmosphere in cyclone prone area. The dynamic load stress analysis shall be done as per ASCE-7 analysis method, the minimum designs loads for buildings and other structures or the uniform builder’s codes. Wind load is a transient, live load (or dynamic load) applied to piping systems exposed to the effects of the wind. Obviously the effects of wind loading can be neglected for indoor installation. Wind load can cause other loads, such as vibratory loads, due to reaction from a deflection caused by the wind. The design wind speed is determined from Governing Code and ASCE-7. Load assumptions for buildings, although a minimum of 161 km/h (100 miles per hour) should be used. By manipulating Bernoulli’s equation, the following equation may be obtained to calculate the horizontal wind load on a projected pipe length.
FW =CW1 x VW 2 x CD x Do
DYNAMIC
Where: FW = design wind load per projected pipe length, N/m (lb/ft); VW = design wind speed, m/s (miles/hr); CD = drag coefficient, dimension less; Do = pipe (and insulation) outside diameter, mm (in); CW1 = constant, 2.543 x 10-6 (N/m) / [mm (m/s)]; (2.13 x 10-4 (lb/ft) / [in (mile/hr)]). The drag coefficient is obtained from ASCE 7 and is a function of the Reynolds Number, R, of the wind flow across the projected pipe. Re = CW2 x VW xDo Where: Re = Reynolds Number; VW = design wind speed, m/s (miles/hr); Do = pipe (and insulation) outside diameter, mm (in); CW2 = constant, 6.87 s/mm-m (780 hr/in-mile). (iii) Earthquake effects: Piping shall be designed and analyzed for earthquake induced horizontal forces stress analysis per method described in ASCE-7 or the uniform building code. (iv) Vibration effects: Piping may be designed and analyzed for excessive and harmful vibration effects caused due to pressure pulsation, resonance in compressor and wind load. Piping connected to compressors or other rotating equipment shall be carried out with vibration stress analysis and accordingly it should be routed and supported. (v) Discharge reaction: When a fluid is let down or discharged in piping, a reaction proportionate to the discharge pressure, velocity & quantity of fluid is developed in piping. So, a discharge or letdown piping shall be stress analyzed for discharge reaction and accordingly support and loop shall be designed.
(E)
W EIGHT /L OAD
EFFECTS : The stresses on a piping system define the service conditions of the piping system and are a function of the loads on that system. The sources of these loads are internal pressure, piping system dead weight, Insulation weight, and differential expansion due to temperature changes, wind loads, and snow or ice loads. Loads on a piping system are classified as sustained or occasional loads. a. Sustained Weight/Loads: Sustained loads are those loads that do not vary considerably over time and are constantly acting on the system. Examples of sustained loads are the pressures, internal and external, acting on the system and the weight of the system. The weight of the system includes both that of the piping material and the operating fluid. The sustained maximum system operating pressure is the basis for the design pressure. The design temperature is the liquid temperature at the design pressure. The minimum wall thickness of the pipe and the piping components pressure rating is determined by the design temperature and pressure. Although the design pressure is not to be exceeded during normal, steady state operations, short-term system pressure excursions in excess of the design pressures occur. These excursions are acceptable if the pressure increase and the time durations are within code defined limits. Piping codes provide design guidance and limits for design pressure excursions. If a code does not have an over-pressure allowance, transient conditions are accounted for within the system design pressure. A reasonable approach to over-pressure conditions for applications without a specific design code is: (1) For transient pressure conditions, which exceed less than 10 percent of the total operating time, neglect the transient and do not increase the design pressure. (2) For transients whose magnitude or duration is greater than 10 percent of the design pressure or operating time, increase the design pressure to pressure transients are addressed in the governing
code. b. Live Weight/load effects: The live loads in piping includes the weight of the medium being transported or the medium used for testing together with surrounded ice formed on pipe both due to environmental and operating conditions. A pipe shall be designed as per the above live load effect. c. Dead Weight/load: These loads consist of the weight of piping components, insulation, and other superimposed permanent loads supported by the piping. Dead weight is the dead load of a piping system or the weight of the pipe and system components. Dead weight generally does not include the weight of the system fluid. The weight of the fluid is normally considered an occasional load by code. A sustained load that is analyzed is the load from the earth potential for deformation; the effects of an earth load on flexible piping and rigid piping are analyzed differently. Governing Code addresses earth loads on buried flexible piping. The earth load on rigid piping may be calculated using the following formula. WxH FE = kPa Where: FE = earth load, kPa (psi); W = soil weight, kg/m3 (lb/ft3); typically 1,922 kg/m3 (120 lb/ft3); H = height of cover, m (ft); a = conversion factor, 102 kg/m2/kPa (144 lb/ft2 /psi). d. Occasional Weight/Loads: Occasional loads are those loads that act on the system on an intermittent basis. Examples of occasional loads are those placed on the system from the hydrostatic leak test, seismic loads, and other dynamic loads. Dynamic loads are those from forces acting on the system, such as forces caused by water hammer and the energy released by a pressure relief device. Another type of occasional load is caused by the expansion of the piping system material. An example of an expansion load is the thermal expansion of pipe against a restraint due to a change in temperature. e. Snow and ice loads: Snow and ice loads are live loads acting on a piping system. For most heavy snow climates, a minimum snow load of 1.2 kPa (25 psf) is used in the design. In some cases, local climate and topography dictate a larger load. This is determined from ANSI A58.1, local codes or by research and analysis of other data. Snow loads can be ignored for locations where the maximum snow is insignificant. Ice build-up may result from the environment, or from operating conditions. The snow loads determined using ANSI A58.1 methods assume horizontal or sloping flat surfaces rather than rounded pipe. Assuming that snow lying on a pipe will take the approximate shape of an equilateral triangle with the base equal to the pipe diameter, the snow load is calculated with the following formula. WS = ½ n Do SL Where: n = conversion factor, 10-3m/mm (0.083 ft/in); WS = design snow load acting on the piping, N/m (lb/ft); Do = pipe (and insulation) outside diameter, mm (in); SL = snow load, Pa (lb/ft). Ice loading information does not exist in data bases like snow loading. Unless local or regional data suggests otherwise, a reasonable assumption of 50 to 75 mm (2 to 3 in) maximum ice accumulation is used to calculate an ice loading. f. Seismic loads: Seismic loads induced by earthquake activity are live/dynamic loads. These loads are transient in nature. Seismic loads may influence piping systems. Seismic zones for most
geographical locations can be found in relevant Code, American Water Works Association (AWWA) D110, AWWA D103, and Seismic Protection for Mechanical Electrical Equipment. ASME B31.3Chemical Plant and Petroleum Refinery Piping require that the piping be designed for earthquake induced horizontal forces using the methods of ASCE 7 or the Uniform Building Code. Hydraulic loads are by their nature transient loads caused by an active influence on a piping system. Examples of dynamic loads inherent to piping systems are pressure surges such as those caused by pump starts and stops, valve actuation, water hammer, and by the energy discharged by a pressure relief valve. Examples of hydraulic loads causing pressure transients and the effect upon the design are provided in relevant Code. Vibration in a piping system is caused by the impact of fluctuating force or pressure acting on the system. Mechanical equipment such as pumps can cause vibrations. Typically the low to moderate level of periodic excitation caused by pumps do not result in damaging vibration. The potential for damage occurs when the pressure pulses or periodic forces equate with the natural resonant frequencies of the piping system. Relevant Code for Noise and Vibration Control provides design recommendations for vibration control, particularly vibration isolation for motor-pump assemblies. In addition, relevant Code recommends the following vibration isolation for piping systems: For connections to rotating or vibrating equipment, the first three supports nearest the vibrating equipment should have a static deflection equal to ½ of that required for the equipment; the remaining pipe supports should have a static deflection of 5 to 12.5 mm (0.2 to 0.49 in); Provide a minimum 25 mm (1 in) clearance for a wall penetration, support the pipe on both sides of the penetration to prevent the pipe from resting on the wall, and seal the penetration with a suitable compound (fire- stop system, if required); Use neoprene isolators in series with steel spring isolators; Always include a neoprene washer or grommet with ceiling hangers; and Inspect hanger rods during installation to ensure that they are not touching the side of the isolator housings. Flexible pipe connections should have a length of 6 to 10 reinforced elastomeric piping. Tie-rods are not used to bolt the two end flanges together. g. Live loads: Live loads can result from the effects of vehicular traffic and are referred to as wheel loads. Above loads are only addressed during the design of buried piping. In general, wheel loads are insignificant when buried at “shallow” depths. The term shallow is defined based upon both sitespecific conditions and the piping material. “However, as a rule, live loads diminish rapidly for laying depths greater than about four feet for highways and ten feet for railroads.” Wheel loads are calculated using information in AASHTO H20 and guidance for specific materials such as AWWA C150 (ductile-iron and metallic), AWWA C900 (PVC) and AWWA C950 (FRP). For example, wheel loads for rigid metallic piping over an effective length of 0.91 m (3 ft) can be calculated using the following formula. CRPF FW = b Do Where: F W = wheel load, kPa (psi); C = surface load factor, see AWWA C150, Table 10.6 M/10.6; R = reduction factor for a AASHTO H20 truck on an unpaved or flexible paved road, see AWWA C150,
Table 10.4M/10.4; P = wheel weight, kg (lb); typically 7,257 kg (16,000 lb); F = impact factor; typically 1.5; b = conversion factor, 0.031 kg/m/kPa (12 lb/ft/psi); and Do = pipe outside diameter, mm (in).
(F)
THERMAL
EFFECTS : (i) Thermal loads due to restraints: Forces resulting from thermal expansion and contraction include loads applied to a piping system because of at restraints or anchors that prevent movement of the piping system. Finally, loads can be introduced in the system by combining materials with different coefficients of expansion. Movements to a piping system can cause loads to be transmitted to the system. These loads can be transferred through anchors and supports. (ii) Load due to temperature gradients: These loads are developed from stresses in pipe walls due to large rapid temperature changes or due to unequal temperature distribution or due to stratified two phase flow created by flow of fluid at or near its boiling temperature and at a certain flow rate. This effect causes large circumferential temperature gradients and possibly unacceptable stresses at anchors supports, guides and within pipe walls. Two-phase flows also generate excessive pressure oscillations and surges, which may damage the pipe. This effect shall be taken into account while designing a pipe at higher temperature. (iii) Thermal loads due to difference in expansion characteristics: When pipe has to be designed with two different materials welded together such as bimetallic, lined, jacketed or metallic nonmetallic piping then due to difference in thermal expansion of the two metals, loads is resulted. This effect shall be taken into account when designing two-metal pipes at higher temperature. (iv) Load due to movement of supports, anchors and equipment effects: Sometimes supports, anchor or equipment nozzles moves or shifts due to flexibility, thermal expansion of equipment, support or anchor and due to settlement, tidal movement or sway. This effect of movement of supports anchor or equipment nozzle shall be taken into account while designing piping in above condition. (G) Reduced ductility effects: Sometimes, the ductility of the piping material is reduced due to welding, heat treatment, forming, bending or operating at low temperatures or due to chilling effect of sudden loss of pressure on highly volatile fluids. It damages the piping. So, the harmful effect of rescued ductility shall be taken into account while designing of piping.
(G)
CYCLIC
EFFECTS : Due to increase & decrease (large fluctuation) in pressure or temperature of the fluid in pipe or other kind of cyclic effect, a fatigue is developed in the piping, which affects it badly. Care shall be taken for harmful effect of fatigue due to cycling nature of pressure, temperature or any other kind, if any.
(H)
AIR
CONDENSATION EFFECTS : When a piping is operating below -191 C ambient temperature, condensation and oxygen enrichment takes place heavily which shall be taken care when designing of piping below-1910 C atmospheric condition. All the above design condition are described here in detail and shall be considered for case to case desponding on the criticality of that particular condition effect by the designer. All the above design conditions are very important and play very important role depending on place-to-place and environmental condition prevails in the area. For example, in earthquake prone the earthquake design condition has to be taken at first priority while designing the pipe in earthquake prone area. 0
Similarly, in coastal area like Bangladesh where cyclone is hitting the area, wind effect factor of design condition plays important role.
4.4 1”
Piping Design Criteria “Part-
The basic design of the pipe is done by the Process Engineer to find out the pipe diameter to handle a particular quantity of the fluid. The Detail Engineering and Design of the piping system is done based on the diameter of the pipe. The Detail Engineering and Design of the piping is done by two fundamental methods as mentioned below: Method 1: “Temperature-Pressure Ratings” Design Criteria. Method 2: “Allowable Stress & Strain Calculation Based” Design Criteria.
4.4.1 “Temperature-Pressure Ratings Design Criteria” There are many standards and codes in which piping components are properly designed and listed as per the established “Temperature-Pressure Ratings”. According to the established TemperaturePressure Ratings, Fluid Service, and Corrosion Allowance, the piping and piping component’s material, dimensions, thickness, end/face to be used in a piping system are given in various “Piping Material Specification” and Codes. Interpolation of Ratings between two Temperatures: The Ratings are the maximum allowable nonshock working gauge pressure at the temperature shown in the Rating Tables at certain interval of temperature. Intermediate Temperature–Pressure Rating can be obtained by a linear graph drawn between the two pressures and corresponding two temperatures. For example, two pressures and corresponding two temperatures are taken from class 150# Rating and a graph is drawn here below in Figure. By linear interpolation, as shown in the adjacent graph, the pressure rating at 2200C is calculated as 13.5 Kg / cm2.
Fig: Interpolation of Ratings between two temperatures. Temperature Rating: In practice, the material temperature is taken as the same of the fluid temperature. For any Rating Temperature below –290C, the Pressure is not greater than the pressure shown at –290C. The primary consideration in establishing the temperature rating is to ascertain the adequate wall thickness of the pipe, flange and flanged fittings to sustain the stresses due to pressure and other loading at different rating classes. Pressure Rating: The pressure rating is the safe working or operating maximum pressure in the line with respect to the Working Temperature. It is available in different Codes and Standards based on the Materials’ Stress-Strain Characteristics. Flange Rating: The Temperature-Pressure Ratings for flange are established by ASME B16.5 on the basis of prime factor of hydro testing of the flanged fittings to the bursting and by providing a factor of safety of 3.0 at the rated working pressure and ambient temperature. ASME/ANSI B16.5 Society establishes the temperature-pressure ratings, given in the tabular form, for all materials at different flange ratings by using Formula as, (Pr x SI) PT = ▬▬▬▬ 8750
Where, PT = rated working pressure in psig for specified material at temperature T. Pr = Pressure rating as per Class in Psig. SI = Selected stress in Psig for specified material at Temperature T.
Maximum Allowable non-shock Pressure (psig) Temperature Pressure Class (lb) 0 ( F) 150 300 400 600 900 1500 Hydrostatic Test Pressure (psig) 450 1125 1500 2225 3350 5575 -20 to 100 285 740 990 1480 2220 3705 200 260 675 900 1350 2025 3375 300 230 655 875 1315 1970 3280 400 200 635 845 1270 1900 3170
2500 9275 6170 5625 5470 5280
500 600 650 700 750 800 850 900 950 1000
170 140 125 110 95 80 65 50 35 20
600 550 535 535 505 410 270 170 105 50
800 730 715 710 670 550 355 230 140 70
1200 1095 1075 1065 1010 825 535 345 205 105
1795 1640 1610 1600 1510 1235 805 515 310 155
2995 2735 2685 2665 2520 2060 1340 860 515 260
Table: Pipe, Flange, Valves & Fittings’ ANSI Rating S. N. 1 2 3 4 5 6 7 8 9 10 11 12
Service
Pressure Rating Class Non- Corrosive Hydrocarbons and 150 lb ANSI Glycol Non- Corrosive Hydrocarbons and 300 lb ANSI Glycol Non- Corrosive Hydrocarbons and 400 lb ANSI Glycol Non- Corrosive Hydrocarbons and 600 lb ANSI Glycol Non- Corrosive Hydrocarbons and 900 lb ANSI Glycol Non- Corrosive Hydrocarbons and 1500 lb ANSI Glycol Non- Corrosive Hydrocarbons and 2500 lb ANSI Glycol Air 150 lb ANSI Water 150 lb ANSI Steam and Steam Condensate 150 lb to 600 lb ANSI Drains and Sewers 150 lb ANSI Flare and Industrial Waste 150 lb ANSI
ANSI Rating
150#
End Face R.F
300#, 400#, R.F
Flange Description FACE FINISH
Gasket Type
Serrated Finish (250 CAF AARH) SPWD Serrated Finish (125 SPWD
,
4990 4560 4475 4440 4200 3430 2230 1430 860 430
600# 900#, 1500#, R.T.J 2500#
AARH) Hardness of Groove: Carbon Steels: 140 BHN; Alloy Steels: 150 BHN Stainless Steels: 140160 BHN.
Octagonal Metallic Ring Gasket
Notes: R.F = Raised Face; CAF = Compressed Asbestos Gasket; # = Ponds; SPWD = Spiral Wound Gasket; R.T.J = Ring Type Joint; 125 AARH = means 125 to 200 AARH Serrated Finish 250 AARH = means 250 to 500 AARH Serrated Finish 63 AARH = means 32 to 63 AARH Serrated Finish All flanges should conform to the following Codes: ANSI RATING
Flange Size
150#, 300#, 400#, 600#, 900#, 1500#, & 2500# 150#, 300#, 400#, & 600# 900# & 1500# 2500#
Up to 24” Dia.
Design Code ANSI B16.5
26” to 60” Dia. API 605 26” to 36” Dia. MSS SP-44 For all sizes API STD 6A
Flanges should be in accordance with the following codes: Flange’s threads should confirm to ANSI B2.1 unless otherwise it is specified; 150# to 2500# Class up to 24” NB should be as per ANSI B16.5; 150# to 2500# Class 26” NB and larger should be as per API 605; Above 2500# Class it should be as per API Std. 6A. Flange Face should be serrated finish (Concentric or Spiral) to 250 to 500 AARH as per MSS-SP-6 unless otherwise specified. Smooth Finish Face should be serrated finish up to 125 AARH only. Weld Neck flanges should be manufactured to suit the pipe bore and thickness. Hardness of the flange face for Ring Joint Type Gasket: The minimum Brinnell Hardness of the flange face for Ring Joint Type gasket should be, such as, for Carbon Steel = 120; 1% to 5% Cr Steel = 150; Stainless Steel type 304, 316, 347 = 180 and Stainless Steel type 304L, 316L = 180. Temperature-Pressure Rating: The allowable working pressures for Pipe are calculated from the stress values and relevant Formulae as detailed in ASME B31.3. Pressure - Temperature Ratings chart is derived from ASME B31.3 to provide a general comparative guide to working pressures for different pipe wall thicknesses. The Temperature-Pressure Chart is reproduced here as a general guide only. It has not
been updated to reflect any subsequent changes to ASME B31.3. It is not intended as a recommendation of allowable working pressures for calculation exact working pressures, people should refer to ASME B31.3, as well as any other relevant piping codes or industry regulations. The ASME Code for Pressure Piping including allowable stress values (SE) for metal temperatures up to 595°C for Carbon Steel Pipe, but cautions that conversion of carbides to graphite (graphitization) may occur in Carbon Steel Pipes after prolonged exposures to temperatures over 425°C. For this reason, with temperatures above 425°C it is recommended that Alloy Steel Pipes should be used. Allowable Stress values (SE) used in tabulated calculations is those approved for piping systems which come under Section B31.3 of the code. The Pressure/Temperature Chart lists maximum allowable pressure ratings for Seamless Carbon Steel Pipe Grade B, with plain ends, at temperatures up to 425°C. Pressure-Temperature Ratings show the maximum allowable working pressures at the temperatures from -20 0F to the maximum allowable temperature for the materials. They are established by the stress calculations utilizing the minimum wall thickness and the maximum allowable stress of the materials at specified temperatures. The maximum allowable stress for any kind of Pipe and piping component material always decreases as the temperature increases. The maximum allowable working pressure of any kind of Pipe and piping component material always decreases as the temperature increases, as shown in the Pressure-Temperature Rating Tables. American National Standard Institute Maximum allowable non-shock pressure (psig) and temperature ratings for steel pipe flanges and flanged fittings according the American National Standard ANSI B16.5 - 1988. Step 1: Determine the maximum operating pressure and temperature. Step 2: Refer to the pressure rating table for the piping material group, and starting from the class 150 lb, go at the Pressure-Temperature rating that is the next highest above the maximum operating Pressure-Temperature Rating of the fluid. Step 3: Proceed through the table columns on the selected temperature row until a pressure rating is reached that exceeds the maximum operating Temperature. Step 4: The column label at which the maximum operating pressure is exceeded at a temperature equal to or above the maximum operating temperature is the required Temperature at which the suitable Pipe, Flange and Fittings and Valve materials and their Schedule/Thickness are given. Several organizations and associations have published specifications that provide materials and dimensional information as well as pressure specifications at different temperatures. For convenience, relevant portions of the American National Standard Institute B 16.34 -1996, Pressure Temperature Ratings are reproduced below: PIPE TEMPERATURE-PRESSURE RATING (Pressure in Kg/cm2) TEMP. CARBON STEEL 0 C API A106 5L GR B GR B -250 ---
A335 GR P5 --
-196
--
--
--
RATING: 150#
ALLOY STEEL A335 A335 GR GR P9 P11 ----
--
A335 GR P22 ---
-80
--
--
--
--
--
--
-45
--
--
--
--
--
--
-29
19.90
19.90 19.90
19.90 19.90 19.90
38
19.90
19.90 19.90
19.90 19.90 19.90
100
18.00
18.00 18.00
18.00 18.00 18.00
150
16.10
16.10 16.10
16.10 16.10 16.10
200
14.20
14.20 14.20
14.20 14.20 14.20
250
12.30
12.30 12.30
12.30 12.30 12.30
350
8.50
8.50
8.50
8.50
8.50
400
6.60
6.60
6.60
6.60
6.360 6.60
500
4260C5.60 4260C 2.80 5.60 --5370C 1.40
2.80
2.80
550
L.T.C.S.
2.80
5370C 5370C 5370C[ 1.4 1.40 1.4
PIPE TEMPERATURE-PRESSURE RATING (Pressure in Kg/cm2) TEMP. 0 C
8.50
RATING: 150#
-250
A333 GR 3 --
A333 GR 6 --
STAINLESS STEEL A312 TP TP TP 304 316 321 19.30 ---
-196
--
--
19.30
--
--
-80
19.90
--
19.30
--
--
-45
19.90
18.70
19.30
--
--
-29
19.90
18.70
19.30
19.30 19.3
38
19.90
18.70
19.30
19.30 19.3
100
800C 18.60
800C 17.90
16.00
16.20 16.0
150
--
--
14.10
14.60 14.2
200
--
--
12.80
13.80 13.5
250
--
--
11.90
11.90 11.9
350
--
--
8.50
8.50
8.5
400
--
--
6.60
6.60
6.6
500
--
--
2.80
2.80
2.8
550
--
--
5370C 1.10
5370C 5370C 1.10 1.10
FIG: TEMPERATURE-PRESSURE RATING GRAPH
PIPE TEMPERATURE-PRESSURE RATING (Pressure in Kg/cm2) TEMP. 0 C
-250
CARBON STEEL API A106 5L GR B GR B ---
RATING: 300#
ALLOY STEEL A335 GR P5 --
A335 GR P9 --
A335 GR P11 --
A335 GR P22 --
-80
--
--
--
--
--
--
-45
--
--
--
--
--
--
-29
52.0
52.00 52.70 52.70
52.70 52.70
38
52.0
52.00 52.70 52.70
52.70 52.70
100
47.3
47.30 52.50 52.50
49.40 49.70
150
46.1
46.10 51.20 51.20
46.70 46.50
200
44.6
44.60 49.70 49.70
45.60 45.60
250
42.5
42.50 47.20 47.20
44.50 44.50
350
37.7
37.70 41.00 41.00
41.00 41.00
400
35.1
35.10 35.00 36.80
36.80 36.80
500
26.00 26.00
550
4260C 4260C 19.70 26.20 29.2 29.2 --11.00 15.20
600
--
--
650
--
--
6.50
12.00 15.20
7.00
5930C 5930C 6.9 5.90 -6480C 6480C -3.10 3.3
PIPE TEMPERATURE-PRESSURE RATING (Pressure in Kg/cm2) TEMP. 0 C
L.T.C.S.
RATING: 300#
-250
A333 GR 3 --
A333 GR 6 --
STAINLESS STEEL A312 TP TP TP 304 316 321 50.6 ---
-80
52.00
--
50.6
--
--
-45
52.00
49.00
50.6
--
--
-29
52.00
49.00
50.6
50.60 50.60
38
52.00
49.00
50.6
50.60 50.60
100
800C 47.00 --
41.7
42.70 42.30
150
800C 50.50 --
37.0
38.80 38.24
200
--
--
33.4
36.40 35.00
250
--
--
31.0
34.10 32.74
350
--
--
28.6
30.60 29.88
400
--
--
28.0
29.60 29.07
500
--
--
26.5
27.10 27.00
550
--
--
5370C 22.6
5370C 5370C 25.40 24.42
600
--
--
--
--
--
650
--
--
--
--
--
FIG: TEMPERATURE-PRESSURE RATING GRAPH PIPE TEMPERATURE-PRESSURE RATING (Pressure in Kg/cm2) TEMP. 0 C
RATING: 400#
-196
CARBON STEEL API A106 5L GR B GR B ---
A335 GR P5 --
A335 GR P9 --
A335 GR P11 --
A335 GR P22 --
-80
--
--
--
--
--
--
ALLOY STEEL
-45
--
--
--
--
--
--
-29
69.48
69.48
70.10
70.10
70.10
70.10
38
69.48
69.48
70.10
70.10
70.10
70.10
100
63.20
63.20
68.70
68.70
66.00
66.50
150
60.50
60.50
67.60
67.60
63.50
63.50
200
59.40
59.40
65.80
65.80
61.60
60.60
250
56.50
56.50
62.40
62.40
60.20
60.20
350
50.20
50.20
54.40
54.40
54.40
54.40
400
45.41
45.41
49.10
49.40
49.40
49.10
500
35.00
37.00
37.00
550
4260C 4260C 26.40 38.40 38.40 --14.60
20.50
16.40
20.60
600
--
--
8.01
9.50
5930C 5930C 9.10 10.5
650
--
--
6480C 4.00
6480C 4.5
PIPE TEMPERATUREPRESSURE RATING (Pressure in Kg/cm2) TEMP. 0 C
-196
L.T.C.S. A333 GR 3 --
A333 GR 6 --
RATING: 400#
STAINLESS STEEL A312 TP TP TP 304 316 321 67.48 ---
-80
69.48
--
67.48 --
--
-45
69.48
64.90
67.48 --
--
-29
69.48
64.90
67.48 67.48
67.48
38
69.48
64.90
67.48 67.48
67.48
100
800C 61.00 --
55.40 57.10
56.00
150
800C 64.40 --
49.40 51.50
50.40
200
--
--
44.10 47.50
46.00
250
--
--
41.40 45.10
43.10
350
--
--
37.50 40.70
38.60
400
--
--
36.40 38.80
37.80
500
--
--
33.15 34.14
34.10
550
--
--
5370C 5370C 30.10 33.10
5370C 32.50
600
--
--
--
--
650
--
--
--
FIG: TEMPERATURE-PRESSURE RATING GRAPH PIPE TEMPERATURE-PRESSURE RATING (Pressure in Kg/cm2)
RATING: 600#
TEMP. CARBON STEEL 0 C API A106 5L GR B GR B -196 ---
ALLOY STEEL A335 A335 A335 GR GR GR P5 P9 P11 ----
A335 GR P22 --
-80
--
--
--
--
--
--
-45
--
--
--
--
--
-29
104.0 104.0
105.4 105.4 105.4
105.4
38
104.0 104.0
105.4 105.4 105.4
105.4
100
94.00 94.66
104.0 104.0 99.80
100.0
150
92.30 92.30
102.3 102.3 94.28
95.08
200
89.35 89.35
99.15 99.15 92.45
91.05
250
85.05 85.05
93.50 93.50 90.04
89.80
350
75.00 75.00
80.00 80.00 80.00
80.00
400
68.38 68.38
72.66 73.00 73.00
73.00
500
54.68
550
4260C 4260C58.0 40.58 54.00 54.88 58.0 --22.87 31.56 24.00
600
--
--
650
--
--
30.40
12.86 14.00 5930C10.5 5930C 15.5 -6480C 6480C -6.12 6.8
PIPE TEMPERATURE-PRESSURE RATING (Pressure in Kg/cm2) EMP. 0 C
--
L.T.C.S.
RATING: 600#
-196
A333 GR 3 --
A333 GR 6 --
STAINLESS STEEL A312 TP TP TP 304 316 321 101.0 ---
-80
104.0
--
101.0
--
--
-45
104.0
97.54
101.0
--
--
-29
104.0
97.54
101.0
101.0 101.0
38
104.0
97.54
101.0
101.0 101.0
100
800C 94.50 --
83.00
86.00 84.80
150
800C 103.0 --
74.15
78.00 76.24
200
--
--
66.21
73.20 69.60
250
--
--
62.32
68.50 64.83
350
--
--
57.22
62.10 59.60
400
--
--
55.00
59.10 57.20
500
--
--
53.21
54.60 53.84
550
--
--
5370C 45.24
5370C 5370C 50.20 50.16
600
--
--
--
--
--
65 0
--
--
--
--
--
FIG: TEMPERATURE-PRESSURE RATING GRAPH
TEMPERATURE-PRESSURE RATING FOR PIPE (Pressure in Kg/cm2)
TEMP. 0 C
RATING: 900#
CARBON ALLOY STEEL STEEL API A106 A335 A335 A335 A335 5L GR B GR GR GR GR GR B P5 P9 P11 P22
-29
156.1 156.1 158.1 158.1 158.1
158.1
38
156.1 156.1 158.1 158.1 158.1
158.1
100
142.5 142.5 157.2 157.2 148.8
150.0
150
137.4 137.4 153.5 153.5 141.0
141.7
200
133.4 133.4 148.6 148.6 138.8
136.7
250
126.8 126.8 141.6 141.6 135.3
134.6
350
112.2 112.2 122.8 122.8 122.8
122.8
400
101.4 101.4 112.0 112.0 112.0
112.0
500
80.30
550
4260C 4260C 54.83 80.24 80.30 86.8 86.8 --33.52 49.72 41.01
600
--
--
650
--
--
18.94 21.04 5930C20.2 5930C 23.9 -6480C 6480C -9.24 10.69
TEMPERATURE-PRESSURE RATING FOR PIPE (Pressure in Kg/cm2)
TEMP. 0 C
-29
TP 304 151.7
44.83
RATING: 900#
STAINLESS STEEL A312 TP TP TP 316 321 316H 151.7 151.7 151.7
38
151.7
151.7
151.7 151.7
100
124.0
128.3
126.2 128.3
150
110.2
117.1
113.8 117.1
200
99.10
108.2
104.2 108.2
250
92.8
101.0
96.6
101.0
350
85.6
92.6
88.6
92.6
400
83.3
89.2
86.8
89.2
500
79.08
79.56
79.85 79.56
550 600
5370C 67.24 --
5370C 76.26 --
5370C 75.20 74.16 -63.00
650
--
--
--
41.00
FIG: TEMPERATURE-PRESSURE RATING GRAPH
TEMPERATURE-PRESSURE RATING FOR PIPE (Pressure in Kg/cm2) TEMP. CARBON STEEL 0 C API A106 A335 5L GR B GR GR B P5
RATING: 1500#
ALLOY STEEL A335 A335 A335 GR GR GR P9 P11 P22
-29
260.5 260.5
263.6
263.6 263.6 263.6
38
260.5 260.5
263.6
263.6 263.6 263.6
100
236.4 236.4
259.6
259.6 248.0 249.2
150
228.6 228.6
252.3
252.3 233.5 234.6
200
222.8 222.8
248.2
248.2 231.3 228.0
250
212.5 212.5
233.7
233.7 225.7 225.0
350
188.0 188.0
203.7
203.7 203.7 203.7
400
170.2 170.2
185.2
186.0 186.0 186.0
500
132.0 132.0 132.0
550
4260C 4260C144.1 98.75 144.1 --52.56
600
--
--
650
--
--
78.44 64.16 81.40
26.04
30.10 5930C 5930C 33.6 39.6 -6480C15.72 6480C -17.98
700 750 815
TEMPERATUREPRESSURE RATING FOR PIPE (Pressure in Kg/cm2) TEMP. 0 C TP
RATING: 1500#
STAINLESS STEEL A312 TP TP
TP
-29
304 253.1
316 253.1
321 253.1
347 253.1
38
253.1
253.1
253.1
253.1
100
208.5
214.5
210.4
210.4
150
182.4
196.7
189.2
189.2
200
165.0
184.0
173.6
173.6
250
153.6
168.0
161.0
161.0
350
142.1
154.0
147.1
147.1
400
138.5
146.3
144.2
144.2
500
131.4
135.0
135.7
135.7
550
5370C113.0
125.8
600
--
5370C127.40 5370C 125.10 ---
650
--
--
94.8
--
102.4
700
48.13
750
26.70
815
14.00
FIG: TEMPERATURE-PRESSURE RATING GRAPH EMPERATURE-PRESSURE RATING FOR PIPE (Pressure in Kg/cm2)
TEMP. 0 C
-29
CARBON STEEL API A106 5L GR B GR B -433.0
RATING: 2500#
ALLOY STEEL A335 GR P5
A335 GR P9
A335 A335 GR GR 22 11
439.0
439.0
439.0 439.0
38
--
433.0
439.0
439.0
439.0 439.0
100
--
393.6
436.1
436.1
412.1 414.1
150
--
383.2
424.5
424.5
390.1 392.2
200
--
371.8
413.4
413.4
382.0 376.1
250
--
350.8
389.9
389.9
368.1 364.2
350
--
312.6
340.4
340.4
340.4 340.4
400
--
279.2
300.0
302.2
302.2 302.2
500
--
4260C241.1 160.4
218.0
220.1 220.1
550
--
--
90.30
138.3
94.45 120.2
600
--
--
52.60
58.40
650
--
--
5930C 5930C 56.15 66.21 -6480C26.0 6480C30.12 --
700
--
--
--
--
--
--
750
--
--
--
--
--
--
815
--
--
--
--
--
--
EMPERATURE-PRESSURE RATING FOR PIPE (Pressure in Kg/cm2)
TEMP. 0 C
STAINLESS STEEL A312
RATING: 2500#
-29
TP 304 421.2
TP 316 421.0
TP 321 421.0
TP 316H 421.2
38
421.2
421.0
421.0
421.2
100
351.2
359.5
356.1
359.5
150
305.4
321.1
314.5
321.1
200
269.0
304.4
283.1
304.4
250
258.1
281.0
270.5
281.0
350
229.5
257.3
240.6
257.3
400
224.8
244.5
232.9
244.5
500
219.8
226.1
225.9
226.1
550
183.2
212.2
207.5
212.2
600
5370C 212.0 --
5370C 208.5 --
175.1
650
5370C 188.6 --
700
--
--
--
80.46
750
--
--
--
44.27
815
--
--
--
24.24
116.4
FIG: TEMPERATURE-PRESSURE RATING GRAPH
P IPE S PECIFICATION Piping Materials Specification: Piping Material Specification is prepared in the form of a table in which, “Temperature-Pressure Rating” (Piping Class) is the main governing parameter. The Detail Engineering and Design of the piping is done with the help of “Piping Material Class”, and “Temperature-Pressure Rating” and “Piping Materials Specification”. Piping materials have been categorized in different groups called “Piping Material Class” with respect to Flange Ratings and Materials as mentioned below. Nomenclature for “Piping Class” is fixed with three X, such as: XXX
1st X : It indicates the rating of the piping system, such as, 1st letter “A” indicate the Flange Rating = 150 # 1st letter “B” indicate the Flange Rating = 300 # 1st letter “C” indicate the Flange Rating = 400 # 1st letter “D” indicate the Flange Rating = 600 # 1st letter “E” indicate the Flange Rating = 900 # 1st letter “F” indicate the Flange Rating = 1500 # 1st letter “G” indicate the Flange Rating = 2500 # 2nd X : It represents some times single digit or sometimes double digits, which indicate the material of the piping system, such as: If it is single digit like 1, it indicates normal grade of material. If it is single digit like 2, it indicates IBR grade of material. If it is single digit like 3, it indicates commercial grade of material. If it is single digit like 4, it indicates Low Temperature grade of material. If it is double digit like 10, 11, 12, etc., it indicates superior grade material with conditions, in main group. If it is double digit like 30, 31, 32, etc., it indicates superior grade material with conditions, in main group. If it is double digit like 40, 41, 42, etc., it indicates superior grade material with conditions, in main group. 3rd X : It indicates the main material of the piping system, such as: A indicates Carbon Steel B indicates C-½ MO Alloy steel (P1) C indicates 1Cr-½ Mo Low Alloy steel (P11, P12) D indicates 1¼ Cr-3/4 Mo Alloy Steel (P11, P22) E indicates 2¼ Cr-1.0 Mo Alloy Steel (P22) F indicates 5 Cr-½ Mo Alloy Steel (P5) G indicates 9 Cr-1 Mo Alloy Steel (P9) H indicates 3.5 NI Alloy Steel (A333 Gr 3) K indicates Austenitic Stainless Steel, type 304, 304H, and 304L. L indicates Aluminium & Alloy M indicates Martensitic Stainless Steel type 316, 316H, 321, 321H,347. N indicates Ferrite Stainless Steel type 316L. P indicates Nickel & Alloy R indicates PVC T indicates Cast Iron and Silicon Iron W indicates Cupro-Nickel Y indicates Carbon Steel (Rubber Lined) Z indicates HDPF Example: Suppose “A1A” is a “Piping Class”. The following is the interpretations: Solution: The first letter “A” of the piping class indicates that it is 150# Flange Rating. The second digit “1” of the piping class indicates that it is normal grade of steel, i.e. API 5L Gr.B The third letter “A” of the piping class indicates that it is carbon steel i.e. API 5L Gr.B So, for “A1A” piping class,
the pipe material is API 5L, GR B and Rating is 150#. Piping Material Specification is a summarized and properly compiled document put in a tabular form in which pipe and piping components’ designed detail are listed according to its “Piping Class” or “Temperature-Pressure Rating” combinations for process piping and utility piping. These combinations make a big volume of Piping Material Specification, which is not possible to accommodate in a book. We have given few tables of Piping Material Specification as an example. All the information about pipe and other matching piping components like flanges, fittings are taken from various Codes and Standards and are made available in this book such as materials, their types, end finish, ratings, dimensions, manufacturing standards, corrosion allowance, joining detail, branchconnection, vent & drain connections, temperature gauge connection, pressure gauge connections. Based on the fluid service and a range of temperature-pressure combination, a set of complete information about pipe and piping components are given in such a way that you can complete the piping design properly as per requirement of the code. As mechanical engineers, we have to refer so many books, standards, codes and specifications to design a piping system for handling a various fluid services and at various Temperature-Pressure Ratings. We can find out suitable all information about pipe, flanges, valves, fittings, gaskets, studs and nuts and other piping connections such as vents, drains, temperature gauges, pressure gauge or branch connections at one place. All the above information is arranged in Piping Material Specification as per “Piping Class” and “Flange Rating”. Sometimes, we do not have sufficient time to go through all the above Codes and Standards. Codes and Standards are, sometimes, not available at one place to refer the same. We have to spend huge money and a lot of time to collect or buy the relevant documents or to engage a consultant for designing a small quantity of piping work. Looking into the above difficulties, we have collected and put here at one place a lot of relevant information on the basis of vast study and reference of many books, codes standards and specifications. You may refer the same at one place and design or does modification work of piping system. We have tried to put as much as the information such as, type of materials, corrosion resistance of material, limitations on use of materials etc. and how to select the suitable material. It is also mentioned the different piping components such as pipes, flanges, fittings, valves, gaskets, studs & nuts and their materials, uses, limitations and their selection. Depending on various service conditions and different Temperature-Pressure working conditions, selection and utilization of piping components with particular pipe, changes. To have a proper and well-designed piping network, as per requirement of the codes, standards and specifications, it is necessary to identify the different services, different conditions of temperature, pressure, corrosion resistance, erosion effects and various other affecting factors. Table: Piping Class Piping Class A1A A2A A3A A5A A8A
Piping Rating 150# 150# 150# 150# 150#
Piping Material Carbon Steel; API 5L GR. B Carbon Steel; ASTM A106 GR. B Carbon Steel; IS 1239 Carbon Steel; ASTM A106 GR. B Carbon Steel; API 5L GR. B
A9A A10A A15A A16A A19A A20A A21A A22A A23A A1F A1K
150# 150# 150# 150# 150# 150# 150# 150# 150# 150# 150#
A4D B1A B2A C1A C2A D1A D2A D5A D25A D2D D4F D1K E1A E2A E25A E5E F1A F2A G1A G2A G5M
150# 300# 300# 400# 400# 600# 600# 600# 600# 600# 600# 600# 900# 900# 900# 900# 1500# 1500# 2500# 2500# 2500#
G25N
2500#
Carbon Steel; API 5L GR. B Carbon Steel; API 5L GR. B Carbon Steel; ASTM A106 GR. B Carbon Steel; API 5L GR. B Carbon Steel; API 5L GR. B Carbon Steel; ASTM A106 GR. B Carbon Steel; API 5L GR. B Carbon Steel; API 5L GR. B Carbon Steel; API 5L GR. B Alloy Steel; A335 GR. P5 Stainless Steel; ASTM A312 GR. TP 304 Alloy Steel; A335 GR. P11 Carbon Steel; API 5L GR. B Carbon Steel; ASTM A106 GR. B Carbon Steel; API 5L GR. B Carbon Steel; ASTM A106 GR. B Carbon Steel; API 5L GR. B Carbon Steel; ASTM A106 GR. B Carbon Steel; ASTM A106 GR. B Carbon Steel; ASTM A106 GR. B Alloy Steel; A335 GR. P11 Alloy Steel; A335 GR. P5 Alloy Steel; A335 GR. P11 Carbon Steel; API 5L GR. B Carbon Steel; ASTM A106 GR. B Carbon Steel; ASTM A106 GR. B Alloy Steel; A335 GR. P22 Carbon Steel; API 5L GR. B Carbon Steel; ASTM A106 GR. B Carbon Steel; API 5L GR. B Carbon Steel; ASTM A106 GR. B Stainless Steel; ASTM A312 GR. T P321 Stainless Steel; ASTM A312 GR. TP 316L Table-Piping Material Specifications
Fluid Service: Non-Corrosive Utilities (Above Ground)- Cooling Water, Fire Water, Instrument Air, Plant Air, Instrument Gas, Nitrogen, Carbon Dioxide Gas, Condensate, Boiler Feed Water (N-IBR), DM Water, Treated Water, Raw water.
PIPING CLASS A3A
PIPING MATERIAL SPECIFICATION
ANSI CA RATING 1.5 mm 150# SN ITEM DIAMETER SCH./ FACE DIMN. MATERIAL RANGE FINISH STD. 1 PIPE 0.5” 1.5” HVY IS 1239 IS 1239 BLACK LSW 2.0” 6.0” HVY IS 1239 IS 1239 BLACK LSW 8.0” 16.0” 6.35 mm IS 3589 IS 3589 GR 410 ERW 18.0” 26.0” 8.00 mm IS 3589 IS 3589 GR 410 ERW 28.0” 30.0” 10.0 mm IS 3589 IS 3589 GR 410 2 FLANGE 0.5” 1.5” 150# 125 SF B 16.5 ASTM A105 2.0” 24.0” 150# 125 SF B 16.5 ASTM A105 26.0” 34.0” 150# 125 SF API 605 ASTM A105 3 BLIND 0.5” 24.0” 150# 125 SF B 16.5 ASTM A105 FLANGE 26.0” 34.0” 150# 125 SF API 605 ASTM A105 4 SPACER 0.5” 16.0” 150# 125 SF API 590 ASTM A105 FIG-8 18.0” 24.0” 150# 125 SF API 590 ASTM A105 26.0” 34.0” 150# 125 SF FLG ASTM A516 SPCR STD GR70 5 FITTING 0.5” 1.5” 3000# R=1.5D B16.11 ASTM A105 ALL 2.0” 6.0” PIPE SCH B16.9 ASTM A234 GR WPB MITRE BEND BW 8.0” 34.0” PIPE SCH MTR IS 3589 GR 410 STD CUT REDUCER BW 8.0” 34.0” PIPE SCH RDR IS 3589 GR 410 STD 6 VALVE BODY TRIM GATE SW 0.5” 1.5” 800# API ASTM 13% CR 602 A105 RF 2.0” 24.0” 150# API A216 13% CR 600 GR WPB GLOBE SW 0.5” 1.5” 800# BS ASTM 13% CR 5352 A105 RF 2.0” 8.0” 150# BS A216 13% CR 1873 GR WPB
CHECK
SW
0.5”
1.5”
800#
ASTM A105 RF 2.0” 24.0” 150# A216 BTRFLY GR WPB WAF 3.0” 24.0” 150# A216 GR WPB 7 STUDS A307 GR B NUTS B18.2 A307 GR B 8 GASKET 0.5” 24.0” 2 MM B16.21 IS 2712 GR W/3 RING 26.0” 34.0” 2 MM API IS 2712 GR 605 W/3 9 STRAINER SW 0.5” 1.50” 800# MNF ASTM STD A105 PERM. BW 2.0” 6.0” PIPE SCH MNF A234 STD GR WPB BW 8.0” 24.0” PIPE SCH MNF A234 STD GR WPBW PIPE JOINT & AUXILIARY BRANCH CONNECTIONS CONNECTION ITEM
SIZE
Description
MAINT JOINT PIPE JOINT
ALL
Flanged but 0.5” keep minimum SW, CPLG, 2.0” 3000# BUTT WELD
DRAINS
ALL
VENTS
1.5”& below 2.0”& above
ALL
SW, CPLG, 3000# 0.75” NB, PIPE SW, CPLG, 3000# 0.75” NB, PIPE
BS 5352 BS 1868 BS 5155 B18.2
RUN PIPE
BRANCH PIPE
1.5”
0.5” 1.5”
30.0”
0.5” 1.5”
2.0” 6.0”
13% CR 13% CR 13% CR
SS 304 SS 304 SS 304
BRANCH CONNECTION TYPE SW, TEE, 3000# SW, Half Coupling, 3000#
Pipe-to-Pipe connection except equal size branch connection where Equal Tee is used. 8.0” 30.0” Pipe-to-Pipe
connection with reinforcement pad except equal size branch TEMP connection CONN where Equal Tee is used. Note: This Piping Class is workable for Maximum Temperature 65 0C and Maximum Pressure PRESS CONN
ALL
SW, HVY, NIPPLE, 0.75” NB 1.5” NB 200 Tapping on line mm long 4.0” NB pipe (min)
at 10.5 Kg/cm2 for size above 24” NB.
Fluid Service: DM Water, Polished Water.
PIPING CLASS A3Y SN ITEM 1
PIPE SMLS
2
FLANGE
3
BLIND FLANGE SPACER OR FIG-8
4
5
FITTING
PIPING MATERIAL ANSI CORROSION SPECIFICATION RATING ALLOWANCE: NIL 150# DIAMETER RANGE SCH FACE DIMN. Material FINISH STD. 1.0” 1.5” SCH B36.10 API 5L GR B 80 (rubber lined) 2.0” 6.0” SCH B36.10 API 5L GR B 40 (rubber lined) 8.0” 12.0” SCH B36.10 API 5L GR B 20 (rubber lined) 1.0” 12.0” 150# Rubber B 16.5 ASTM A105 (rubber lined) 1.0” 12.0” 150# Rubber B 16.5 ASTM A105 (rubber lined) 1.0” 12.0” 150# Rubber API ASTM A105 605 (rubber lined) 1.0” 12.0” 150# Rubber B 16.5 ASTM A105 (rubber lined) 1.0” 10.0” 150# 125 SF API ASTM A182GR 590 F304 10.0” 12.0” 150# 125 SF API ASTM A182GR 590 F304 1.0” 1.5” 150# R=3.0D B16.11 A234 GR WPB 2.0” 12.0” 150# B16.9 (rubber lined
6
VALVE 1.0” GATE 1.0” GLOBE 1.0” CHECK 1.0”
7
8 9
12.0” 150# 125 SF API 600 8.0” 150# 125 SF BS 1873 12.0” 150# 125 SF BS 1868 12.0” 150# 125 SF MNF STD
1.0”
12.0” 150# 125 SF BS 5155
STUDS
-
-
-
-
NUTS
-
-
-
-
BTRFLY
GASKET 1.0” RING STRAINER 1.0”
PIPE JOINT CONNECTION
&
BODY A351 GR CF8 A351 GR CF8 A351 GR CF8 A216 GR WPB (RBR lined)
SS304 SS304 SS304
A216 GR SS304 WPB (RBR lined)
B18.2
A307 GR B B18.2 A307 GR B B16.21 BUTYLE RUBBER
12.0” 2 MM 12.0” 150# T MNF A403 GR SS 304 TYPE STD WP304 AUXILIARY BRANCH CONNECTIONS
ITEM
SIZE
DESCRIPTION RUN PIPE BRANCH PIPE
PIPE JOINT DRAINS
ALL
FLANGED
ALL
TRIM SS304
1.0” 2.0”
1.0”
BRANCH CONNECTION TYPE 2.0” BW, TEE, SCH 80 12.0” Pipe-to-Pipe connection except equal size OR one size less branch connection where Tee is used.
1” NB 3.0” 12.0” 1.0” SCH 80 VENTS ALL 1” NB SCH 80 PRESS ALL 1” NB CONN. SCH 80 TEMP 1.5” PIPE 1.5” NB SCH 80 CONN. 200 mm long Note: Pipe sizes less than 1” NB should not be used. Diaphragm Valve should be used up to 10 Kg/cm2. Welding should not be carried out after Rubber lining is completed. Natural
Rubber (Soft) lining of S.H. 60 should be completed as per IS 4682 Part-I. The thickness of the lining should be minimum 3 mm. The Bend of size 1.5” and below should be Min. 3D Radius. All sharp edges should be ground off. All Branch Connection should be made with BW Tee welded to WN flange.
Fluid Service: Non-Corrosive Hydrocarbon Process (l/v/g), Kerosene, LPG (gas/oil), Fuel Oil/Gas, Crude Oil, Heavy Naphtha, Wash Water, Demulsified Solution, Ammonia Solution, Corrosion Inhibitor, Steam &Condensate (N-IBR).
PIPING CLASS A1A
PIPING MATERIAL SPECIFICATION
SN ITEM
DIAMETER RANGE 0.5” 1.5” 2.0” 6.0” 8.0” 14.0” 16.0” 24.0”
FACE FINISH -
0.5” 2.0” 0.5”
SCH./ RATING SCH 80 SCH 40 SCH 20 7.92 mm 1.5” 150# 24.0” 150# 24.0” 150#
125 SF 125 SF 125 SF
B 16.5 ASTM A105 B 16.5 ASTM A105 B 16.5 ASTM A105
0.5”
16.0” 150#
125 SF
ASTM A105
18.0”
24.0” 150#
125 SF
0.5” 2.0”
1.5” 3000# 14.0” PIPE SCH 24.0” PIPE
R=1.5D
API 590 API 590 B16.11 B16.9 B16.9
ASTM A234 GR WPBW
1
PIPE
2
FLANGE
3
BLIND FLANGE SPACER OR FIG-8
4
5
FITTING
16.0”
ANSI CORROSION RATING ALLOWANCE: 150# 1.5 MM DIMN. MATERIAL STD. B36.10 API 5L GR B B36.10 API 5L GR B B36.10 API 5L GR B B36.10 API 5L GR B
ASTM A105 ASTM A105 ASTM A234 GR WPB
SCH 6
VALVE GATE
GLOBE
CHECK
7 8 9
STUDS NUTS GASKET STRAINER
ALL ALL RING PERM PERM PERM
PIPE JOINT CONNECTION
&
0.5”
1.5”
800#
2.0”
24.0”
150#
0.5”
1.5”
800#
2.0”
8.0”
150#
SIZE
DESCRIPTION RUN PIPE
MAINT JOINT
ALL
PIPE JOINT
1.5”& below 2.0”& above
FLANGED 0.5” but keep minimum SW, CPLG, 3000# BUTT WELD SW, CPLG, 2.0” 3000# 0.75” NB, PIPE
VENTS
ALL
TRIM 13% CR API 600 A216 GR WCB 13% CR BS 5352 ASTM A105 13% CR
BS 1873 A216 GR WCB 13% CR 0.5” 1.5” 800# BS 5352 ASTM A105 13% CR 2.0” 24.0” 150# BS 1868 A216 GR WCB 13% CR B18.2 A193 GR B7 B18.2 A194 GR 2H 0.5” 24.0” 2 MM B16.21 IS 2712 GR 0/1 0.5” 1.50” 800# MNF ASTM A105 SS STD 304 2.0” 14.0” PIPE SCH MNF A234 GR WPB SS STD 304 16.0” 24.0” PIPE SCH MNF A234 GR SS STD WPBW 304 AUXILIARY BRANCH CONNECTIONS
ITEM
DRAINS ALL
BODY API 602 ASTM A105
SW,
CPLG,
BRANCH PIPE 1.5”
0.5”
1.5”
24.0” 0.5”
1.5”
2.0”
BRANCH CONNECTION TYPE SW, TEE, 3000#
SW, HC, 3000#. 2”X1.5” Tee 10.0” Pipe-to-pipe. Equal size Equal
3000# 0.75” NB, PIPE
PRESS CONN TEMP CONN
12.0”
ALL
SW, HVY, NIPPLE, 0.75” NB 1.5” PIPE 200 Tapping on line mm long 4.0” NB pipe (min)
Tee 24.0” Pipe-to-Pipe with RF. Equal size branch Equal Tee.
Note: Soft-seated ball and Plug Valves can be used up to 200 0C. Pipe fabricated Reducer are permitted.
Fluid Service: Highly Corrosive Sour Service (NACE), Flammable, Non-Lethal, Toxic, Sour Water, Sour Flare, Caustic (Stress Relieved), etc.
PIPING CLASS A12A SN ITEM 1
PIPE SMLS
2
FLANGE
3
BLIND FLANGE SPACER OR FIG-8
4
5
FITTING
PIPING MATERIAL SPECIFICATION
ANSI RATING 150#
DIAMETER RANGE 0.5” 1.5” 2.0” 3.0” 6.0” 8.0” 10.0” 14.0” 0.5” 1.5” 2.0” 24.0” 0.5” 24.0”
SCH./ RATING XXS SCH 160 SCH 80 SCH 60 SCH 40 150# 150# 150#
FACE FINISH 125 SF 125 SF 125 SF
DIMN. STD. B36.10 B36.10 B36.10 B36.10 B36.10 B 16.5 B 16.5 B 16.5
0.5” 16.0” 18.0” 24.0”
150# 150#
125 SF 125 SF
API 590 API 590
ASTM A105 ASTM A105
0.5” 2.0”
PIPE SCH PIPE SCH
R=1.5D
B16.9 B16.9
ASTM A234 G ASTM A234 G
1.5” 14.0”
Corrosion Allowanc 6.0 MM MATERIAL API 5L GR B API 5L GR B API 5L GR B API 5L GR B API 5L GR B ASTM A105 ASTM A105 ASTM A105
16.0” 24.0” 6
PIPE SCH
B16.9
VALVE GATE
GLOBE
0.5”
1.5”
150#
API 602
2.0”
24.0”
150#
A216 GR WCB
0.5”
1.5”
150#
2.0”
8.0”
150#
API 600 BS 5352 BS 1873
0.5”
1.5”
150#
ASTM A105
2.0”
24.0”
150#
2.0”
24.0”
150#
0.5”
24.0”
2 MM
BS 5352 BS 1868 BS 5351 B18.2 B18.2 B16.21
0.5”
1.50”
150#
2.0”
14.0”
16.0”
24.0”
CHECK
BALL
7 8 9
STUDS NUTS GASKET RING STRAINER PERM.
ASTM A234 G BODY ASTM A105
ASTM A105 A216 GR WCB
A216 GR WCB A351 GR CF8 A193 GR B7 A194 GR 2H IS 2712 GR 0/1
PIPE JOINT & AUXILIARY CONNECTION
MNF ASTM A105 STD 150# MNF A234 GR WPB STD 150# MNF A234 GR WPBW STD BRANCH CONNECTIONS
ITEM
SIZE
DESCRIPTION
RUN PIPE
BRANCH PIPE
MAINT JOINT PIPE JOINT
ALL
FLANGED
0.5”
0.5”
1.5”
1.5”& below 2.0”& above
BUTT WELD BUTT WELD 2.0”
24.0” 0.5”
1.5”
Minimum
1.5”
2.0”
BRAN CONN BW, T
Weldo 3000# Tee
24.0” Pipe with R
VENTS PRESS CONN TEMP CONN
ALL
Weldolet, 3000# 0.75”NB, PIPE ALL 0.75” Weldolet, SCH XXS NB NIPPLE 1.5” PIPE FLGD, Tapping on line 4.0” 200 mm pipe (min) long
2”x1.5 size w Tee.
Note: All weld joint should be Post Weld Heat treated. All valve casting should be 100% Rad Velocity of the fluid should be limited to 6.0 m/s
Fluid Service: Hydrogen and Hydrogen bearing Hydrocarbon, Flammable, Toxic but Nonlethal.
PIPING CLASS PIPING MATERIAL SPECIFICATION A5A SN ITEM 1
PIPE SMLS SMLS
2 3 4
5
EFSW FLANGE BLIND FLANGE SPACER OR FIG-8 SPCR FITTING ALL
ANSI RATING 150# DIMN. STD. B36.10 B36.10 B36.10 B36.10 B36.10
CORROSION ALLOWANCE: 1.5 MM MATERIAL
DIAMETER RANGE 0.5” 2.0” 8.0” 16.0” 22.0”
SCH./ RATING 1.5” SCH 80 6.0” SCH 40 14.0” SCH 20 20.0” SCH 10 24.0” 7.92
FACE FINISH -
0.5” 2.0” 0.5”
1.5” 150# 24.0” 150# 24.0” 150#
125 SF 125 SF 125 SF
B 16.5 B 16.5 B 16.5
ASTM A105 ASTM A105 ASTM A105
0.5” 18.0”
16.0” 150# 24.0” 150#
125 SF 125 SF
API 590 API 590
ASTM A105 ASTM A105
0.5”
1.5”
R=1.5D
B16.11
ASTM A105
2.0”
14.0” PIPE SCH
B16.9
16.0”
24.0” PIPE SCH
B16.9
ASTM A234 GR WPB ASTM A234 GR
3000#
API 5L GR B API 5L GR B API 5L GR B API 5L GR B API 5L GR B
WPBW ASTM A105 TRIM
CAP 6
0.5”
1.5”
3000#
0.5”
1.5”
800#
BS 5352
2.0”
8.0”
150#
BS 1873
0.5”
1.5”
800#
BS 5352
2.0”
24.0” 150#
BS 1868
0.5”
24.0” 150#
BS 5351
STUDS
-
-
-
B18.2
NUT
-
-
-
B18.2
GASKET RING
0.5”
24.0” 5MM
VALVE GLOBE
CHECK
BALL
7
8
B16.11 BODY
9
0.5” STRAINER 2.0” PERM 16.0”
PIPE JOINT CONNECTION ITEM
SIZE
MAINT ALL JOINT
&
ASTM A105 A216 GR WCB ASTM A105 A216 GR WCB A216 GR WCB A193 GR B7 A194 GR 2H
13% CR 13% CR 13% CR 13% CR 13% CR
API 601
SPWD,SS (TFL- filled) 304 1.50” 800# MNF STD ASTM SS 304 A105 14.0” PIPE SCH MNF STD A234 GR SS 304 WPB 24.0” PIPE SCH MNF STD A234 GR SS 304 WPBW AUXILIARY BRANCH CONNECTIONS DESCRIPTION RUN PIPE
FLANGED 0.5” but keep minimum PIPE 1.5”& below SW, CPLG, 2.0” JOINT 2.0”& above 3000# BUTT WELD DRAIN On line<2” SW CPLG 3000# 0.75” pipe
1.5”
BRANCH PIPE 0.5” 1.5”
24.0” 0.5”
1.5”
BRANCH TYPE SW, TEE, 3000# SW, Half Coupling, 3000#, except 2”X1.5” where Tee is used
On line>1.5” VENTS On line<2”
2.0” SW 3000# pipe
10.0”
CPLG 0.75”
On line>1.5”
12.0” 24.0”
PRESS 0.75” PIPE CONN
SW, SCH NIPPLE
80
TEMP 1.5” PIPE CONN. mm long
200 FLG, Tapping on line 4.0” pipe (min)
Pipe-to-Pipe connection except equal size branch connection where Equal Tee is used. Pipe-to-Pipe connection with reinforcement pad except equal size branch connection ere Equal Tee is used.
Note: All weld joint should be Post Weld Heat treated. All valve & Strainer Casting should be 100% Radiographic. Velocity of the fluid should be limited to 6.0 m/s.
Fluid Service: LP Steam, Boiler Feed Water and Superheated LP Steam (IBR).
PIPING CLASS A2A SN ITEM 1
2
PIPE SMLS
EFSW FLANGE
PIPING MATERIAL SPECIFICATION
DIAMETER RANGE 0.5” 2.0” 8.0” 16.0”
1.5” 6.0” 14.0” 24.0”
SCH./ Rating SCH 80 SCH 40 SCH 20 7.92MM
0.5” 2.0”
1.5” 24.0”
150# 150#
ANSI RATING 150#
Corrosion Allowance 1.5 mm MATERIAL
DIMN. STD. B36.10 B36.10 B36.10 B36.10
A106 GR B A106 GR B A106 GR B A672 GR C70 CL2
B 16.5 B 16.5
ASTM A105 ASTM A105
3 4
5
6
BLIND FLANGE SPACER OR FIG-8 SPCR FITTING ALL
0.5”
24.0”
150#
B 16.5
ASTM A105
0.5” 18.0”
16.0” 24.0”
150# 150#
API 590 API 590
ASTM A105 ASTM A105
0.5” 2.0”
1.5” 14.0”
3000# PIPE SCH
B16.11 B16.9
16.0”
24.0”
PIPE SCH
B16.9
ASTM A105 ASTM A234 GR WPB ASTM A234 GR WPBW
VALVE 2.0”
24.0”
150#
125 SF -
API 600
0.5”
1.5”
800#
2.0”
8.0”
150#
125 SF -
BS 1873
0.5”
1.5”
800#
2.0”
24.0”
150#
125 SF 125 SF
BS 1868
STEAM TRAP
0.5”
1.5”
150#
STUDS
-
-
-
-
B18.2
NUTS
-
-
-
-
B18.2
24.0”
2MM
-
B16.21
1.50”
800#
GATE
BS 5352
GLOBE
BS 5352
CHECK
7
8 9
GASKET 0.5” RING STRAINER 0.5” PERM 2.0”
PIPE
BS 1868
Y MNF TYPE STD 14.0” PIPE SCH T MNF TYPE STD 16.0” 24.0” PIPE SCH T MNF TYPE STD JOINT & AUXILIARY BRANCH CONNECTIONS
BODY TRIM A216 GR 13% WCB CR ASTM 13% A105 CR A216 GR 13% WCB CR ASTM 13% A105 CR A216 WCB ASTM A105
GR 13% CR 13% CR
A193 B7 A194 2H IS 2712 W/3 ASTM A105 A234 WPB A234 WPBW
GR GR GR SS 304 GR SS 304 GR SS 304
CONNECTION ITEM
SIZE
DESCRIPTION
MAINT JOINT PIPE JOINT
ALL
FLANGED but 0.5” keep minimum SW, CPLG, 3000# 2.0” BUTT WELD
DRAIN
On line<2” On line>1.5” On line<2”
VENTS
1.5”& below 2.0”& above
0.75” PIPE 1.5” PIPE 200mm long
1.5”
BRANCH PIPE
BRANCH CONNECTION TYPE SW, TEE, 3000#
0.5”
1.5”
24.0” 0.5”
1.5”
SW, Half Coupling, 3000#, except 2”X1.5” where Tee is used
10.0”
Pipe-to-Pipe connection except equal size branch connection where Equal Tee is used. Pipe-to-Pipe connection with reinforcement pad except equal size branch connection where Equal Tee is used.
SW CPLG 3000# 0.75” pipe, Globe, 2.0” SW CPLG 3000# 0.75” pipe, Globe,
On line>1.5”
PRESS CONN TEMP CONN
RUN PIPE
12.0” 24.0”
SW, SCH 80 NIPPLE, Globe FLG, Tapping on line 4.0” pipe (min)
Note: All pipes and piping components should be hydrostatic tested and certified by IBR Inspector in the Form IIIA for pipe & IIIC foe piping components. The Carbon contents of all pipes and piping components should not exceeds 0.25%. Soft seated ball and Plug Valves can be used up to 200 0C. Pipe fabricated Reducer are not permitted for use.
Fluid Service: Mild to Moderate Corrosive Hydrocarbon, flammable, nonlethal, Fuel Gas, Valv Residue, BIM Reactor Effluents.
PIPING CLASS A1D SN ITEM 1
PIPE SMLS
EFSW
2
3 4
5
6
FLANGE
BLIND FLANGE SPACER OR FIG-8 SPCR FITTING
VALVE GATE
GLOBE
PIPING MATERIAL ANSI RATING SPECIFICATION 150# DIA. RANGE 0.5” 1.5”
CORROSION ALLOWANCE: 1.5 MM DIMN. STD. MATERIAL
SCH./ Face Rating Finish SCH 80 SCH 40 SCH 20 7.92 MM
-
B36.10
A335 GR P11
-
B36.10
A335 GR P11
-
B36.10
A335 GR P11
B36.10
A691 GR 1.25C CL42
ASTM F11 ASTM F11 ASTM F11 ASTM F11 ASTM F11 ASTM F11
2.0”
6.0”
8.0”
14.0”
16.0”
24.0”
0.5”
1.5”
150#
125 SF
B 16.5
2.0”
24.0”
150#
125 SF
B 16.5
0.5”
24.0”
150#
125 SF
B 16.5
0.5”
16.0”
150#
125 SF
API 590
18.0”
24.0”
150#
125 SF
API 590
0.5”
1.5”
3000#
R=1.5D
B16.11
2.0”
14.0”
16.0”
24.0”
PIPE SCH PIPE SCH
0.5”
1.5”
800#
-
2.0”
24.0”
150#
125 SF
0.5”
1.5”
800#
-
2.0”
8.0”
150#
125 SF
B16.9
A182 G
A182 G
A182 G
A182 G
A182 G
A182 G
ASTM A234 G WP11 CL1 B16.9 ASTM A234 G WP11 CL1 BODY TRIM API A182 GR F11 Stellited 602 API A217 GR WC6 Stellited 600 BS A182 GR F11 Stellited 5352 BS A217 GR WC6 Stellited
CHECK
7 8 9
STUDS NUTS Gasket RING STRAINER PERM
0.5”
1.5”
800#
-
2.0”
24.0”
150#
125 SF
0.5”
24.0”
5 MM
-
0.5”
1.50”
800#
Y TYPE
2.0”
14.0”
PIPE SCH PIPE SCH
T TYPE
16.0” 24.0”
PIPE JOINT CONNECTION
&
T TYPE
1873 BS 5352 BS 1868 B18.2 B18.2 B16.21 MNF STD MNF STD MNF STD
A182 GR F11
Stellited
A217 GR WC6
Stellited
A193 GR B16 A194 GR 4 SPWD, SS304, CAF, I & Ring A182 GR F11 SS 304 A234 GR WP11 CL1 SS 304 A234 GR WP11W CL1 SS 304
AUXILIARY BRANCH CONNECTIONS
ITEM
SIZE
DESCRIPTION RUN PIPE
BRANCH PIPE
MAINT JOINT
ALL
1.5”
0.5”
1.5”
PIPE JOINT
1.5”& below 2.0”& above
FLANGED 0.5” but keep minimum SW, CPLG, 2.0” 3000# BUTT WELD
24.0”
0.5”
1.5”
SW, Ha Coupling, 3000#, excep 2”X1.5” wher Tee is used
DRAIN
On line<2” SW CPLG. 0.75” Online>1.5” 3000# pipe, Globe, On line<2” SW CPLG 0.75” Online>1.5” 3000# pipe, Globe,
2.0”
10.0”
Pipe-to-Pipe connection except equal siz branch connection where Equal Te is used. Pipe-to-Pipe connection wi reinforcement pad except equa
VENTS
12.0” 24.0” PRESS CONN
0.75” PIPE
SW, SCH 80 Nipple, Globe
BRANCH CONNECTIO TYPE SW, TEE, 3000
TEMP CONN
1.5” 200 long
PIPE FLG, Tapping on mm line 4.0” pipe (min)
size branc connection where Equal Te is used.
Fluid Service: Non-corrosive Low Temperature Hydrocarbon (Liquid or Vapour)
PIPING CLASS A1H SN ITEM 1
PIPE SMLS
EFSW
2
FLANGE
3
BLIND FLANGE SPACER FIG-8
4
PIPING MATERIAL ANSI RATING SPECIFICATION 150# DIAMETER RANGE 0.5” 1.5”
SCH./ Face Rating Finish SCH 80 -
DIMN. STD.
Corrosion Allowance 1.5 mm MATERIAL
B36.10
A333 GR 3
2.0” 6.0” 8.0” 14.0” 16.0” 24.0”
SCH 40 SCH 20 7.92MM
B36.10 B36.10 B36.10
A333 GR 3 A333 GR 3 A671 GR CF66 CL32
0.5” 2.0” 0.5”
1.5” 24.0” 24.0”
150# 150# 150#
125 SF B 16.5 125 SF B 16.5 125 SF B 16.5
ASTM A350 GR LF3 ASTM A350 GR LF3 ASTM A350 GR LF3
0.5” 16.0” 18.0” 24.0”
150# 150#
125 SF API 590 125 SF API 590
ASTM A350 GR LF3 ASTM A350 GR LF3
0.5” 2.0”
3000# PIPE SCH PIPE SCH
R=1.5D B16.11 B16.9
SPCR 5
FITTING ALL
1.5” 14.0”
16.0” 24.0” 6
VALVE
B16.9
ASTM A350 GR LF3 ASTM A420 GR WPL3 ASTM A420 GR WPL3W BODY TRIM
GATE
0.5”
1.5”
800#
-
API 602
2.0”
24.0”
150#
125 SF
API 600
0.5”
1.5”
800#
-
BS 5352
2.0”
8.0”
150#
125 SF
BS 1873
0.5”
1.5”
800#
-
BS 5352
2.0”
24.0”
150#
125 SF
BS 1868
STUDS
-
-
-
-
B18.2
NUTS
-
-
-
-
B18.2
8
GASKET RING
0.5”
24.0”
5 MM
-
B16.21
9
STRAINER 0.5” PERM 2.0”
1.50”
800#
GLOBE
CHECK
7
16.0” PIPE JOINT CONNECTION
&
A350 Stellited GR LF3 A352 Stellited GR LC3 A350 Stellited GR LF3 A352 Stellited GR LC3 A350 Stellited GR LF3 A352 Stellited GR LC3 A320 GR L7 A194 GR 4 SPWD, SS304, CAF, I&O Ring
Y MNF A350 GR LF3 SS TYPE STD 304 14.0” PIPE T MNF ASTM A420 GR SS SCH TYPE STD WPL3 304 24.0” PIPE T MNF ASTM A420 GR SS SCH TYPE STD WPL3W 304 AUXILIARY BRANCH CONNECTIONS
ITEM
SIZE
DESCRIPTION
RUN PIPE
MAINT JOINT
ALL
FLANGED (Minimum)
0.5”
1.5”
BRANCH PIPE BRANCH CONNECTION TYPE 0.5” 1.5” SW, TEE, 3000#
PIPE
1.5”&
SW, CPLG, 3000# 2.0”
24”
0.5”
1.5”
SW,
Half
JOINT
DRAIN
VENTS
PRESS CONN TEMP CONN
below 2.0”& above On line < 2” On line > 1.5” On line < 2”
On line > 1.5” 0.75” PIPE 1.5” PIPE 200 mm long
BUTT WELD
SW CPLG 3000# 0.75” pipe, Globe, 2.0” SW CPLG 3000# 0.75” pipe, Globe,
12” SW, SCH 80 NIPPLE, Globe FLG, Tapping on line 4.0” pipe (min)
Fluid Service: Non-corrosive Hydrocarbon (Liquid or Vapour) PIPING PIPING CLASS MATERIAL SPECIFICATION A4A SN ITEM DIAMETER RANGE 1 PIPE 0.5” 1.5” 2.0” 6.0” 8.0” 14.0” 16.0” 24.0” 2
3
FLANGE 0.5”
BLIND
Coupling, 3000#, except 2”X1.5” where Tee is used
1.5”
Low
Temperature
ANSI Corrosion RATING Allowance 150# 1.5 mm SCH./ Face DIMN. Rating Finish STD. SCH 80 B36.10 SCH 40 B36.10 SCH 20 B36.10 7.92MM B36.10 150#
2.0”
24.0” 150#
0.5”
24.0” 150#
10.0” Pipe-to-Pipe connection except equal size branch connection where Equal Tee is used. 24.0” Pipe-to-Pipe connection with reinforcement pad except equal size branch connection where Equal Tee is used.
MATERIAL
A333 GR 6 A333 GR 6 A333 GR 6 A671 GR CC70 CL32 125 SF B 16.5 ASTM A350 GR LF2 125 SF B 16.5 ASTM A350 GR LF2 125 SF B 16.5 ASTM A350
4
5
FLANGE SPACER 0.5” 16.0” 150# OR FIG8 18.0” 24.0” 150# FITTING 0.5” ALL 2.0”
1.5”
3000#
14.0” PIPE SCH 16.0” 24.0” PIPE SCH
6
GR LF2 125 SF API ASTM A350 590 GR LF2 125 SF API ASTM A350 590 GR LF2 R=1.5D B16.11 ASTM A350 GR LF2 B16.9 ASTM A420 GR WPL6 B16.9 ASTM A420 GR WPL6W
VALVE
BODY
TRIM
GATE 0.5”
1.5”
2.0”
24.0” 150#
125 SF
0.5”
1.5”
800#
-
2.0”
8.0”
150#
125 SF
0.5”
1.5”
800#
-
2.0”
24.0” 150#
125 SF
STUDS
-
-
-
-
NUTS
-
-
-
-
8
Gasket RING
0.5”
24.0” 2MM
-
A350 GR Stellited LF2 A352 GR Stellited LCB A320 GR L7 B18.2 A194 GR 4 B16.21 IS2712 GR 0/1
9
STRAINER 0.5”
1.50” 800#
Y TYPE
MNF
GLOBE
CHECK
7
800#
-
API 602 API 600 BS 5352 BS 1873
A350 LF2 A352 LCB A350 LF2 A352 LCB
GR Stellited GR Stellited GR Stellited GR Stellited
BS 5352 BS 1868 B18.2
A350 GR LF2 SS 304
RING 2.0” 16.0” PIPE JOINT CONNECTION ITEM
&
SIZE
STD 14.0” PIPE T TYPE MNF A420 GR SS 304 SCH STD WPL6 24.0” PIPE T TYPE MNF A420 GR SS 304 SCH STD WPL6W AUXILIARY BRANCH CONNECTIONS DESCRIPTION RUN PIPE
MAINT ALL JOINT
FLANGED 0.5” but keep minimum PIPE 1.5”& below SW, CPLG, 2.0” JOINT 2.0”& above 3000# BUTT WELD DRAIN On line SW CPLG 3000# 0.75” < pipe, Globe, 2” On line > 1.5” VENTS On line <2” SW CPLG 3000# 0.75” pipe, Globe, On line >1.5” PRESS 0.75” PIPE CONN
TEMP CONN
1.5”
BRANCH PIPE 0.5”
1.5”
24.0” 0.5”
1.5”
SW, Half Coupling, 3000#, except 2”X1.5” where Tee is used
10.0”
Pipe-to-Pipe connection except equal size branch connection where Equal Tee is used. Pipe-to-Pipe connection with reinforcement pad except equal size branch connection where Equal Tee is used.
2.0”
12.0” 24.0” SW, SCH 80 NIPPLE, Globe
1.5” PIPE 200 FLG, Tapping on mm long line 4.0” pipe (min)
BRANCH CONNECTION TYPE SW, TEE, 3000#
Fluid Service: DM Water, Phosphate Solution, Pure Process Liquid, Vapour or Gas, Mild Corrosive Hydrocarbon, Polished Water and Chemicals etc.
PIPING CLASS A1K SN ITEM 1
2 3 4
5
6
PIPE SMLS
EFSW FLANGE BLIND FLANGE FIG-8 SPACER FITTING ALL
PIPING SPECIFICATION DIAMETER RANGE 0.5” 1.5”
MATERIAL ANSI RATING 150#
2.0”
6.0”
8.0”
24.0”
0.5” 2.0” 0.5”
1.5” 24.0” 24.0”
SCH./ Rating SCH 40 SCH 10 SCH 10 150# 150# 150#
0.5” 18.0”
16.0” 24.0”
0.5” 2.0”
1.5” 14.0”
16.0”
24.0”
0.5”
FACE FINISH DIMN. STD. B36.10
Corrosion Allowance NIL MATERIAL A312 GR TP304
-
B36.10
A312 GR TP304
-
B36.10
125 SF 125 SF 125 SF
B 16.5 B 16.5 B 16.5
A358 GR TP304 CL1 A182 GR F304 A182 GR F304 A182 GR F304
150# 150#
125 SF 125 SF
API 590 A182 GR F304 API 590 A182 GR F304
3000# PIPE SCH PIPE SCH
R=1.5D
B16.11 B16.9
1.5”
800#
-
2.0”
24.0”
150#
125 SF
0.5”
1.5”
800#
-
2.0”
8.0”
150#
125 SF
0.5”
1.5”
800#
-
A182 GR F304 A403 GR WP304
B16.9
A403 WP304W BODY TRIM
VALVE GATE
GLOBE
CHECK
API 602 API 600 BS 5352 BS 1873 BS 5352
A182 F304 A351 CF8 A182 F304 A351 CF8 A182 F304
GR Stellited GR Stellited GR Stellited GR Stellited GR Stellited
GR
2.0” STUDS
-
-
-
-
BS 1868 B18.2
NUTS
-
-
-
-
B18.2
8
GASKET RING
0.5”
24.0” 5 MM
-
B16.21
9
STRAINER 0.5” PERM 2.0”
1.50” 800#
7
16.0” PIPE JOINT CONNECTION
&
24.0”
150#
125 SF
Y TYPE 14.0” PIPE SCH T TYPE
24.0” PIPE SCH T MNF TYPE STD AUXILIARY BRANCH CONNECTIONS
ITEM
SIZE
DESCRIPTION RUN PIPE
MAINT JOINT
ALL
PIPE JOINT
FLANGED 0.5” but keep minimum SW, CPLG, 2.0” 3000# BUTT WELD
1.5”& below 2.0”& above On line SW CPLG <2” 3000# 0.75” On line pipe, Globe, >1.5”
DRAIN
VENTS
MNF STD MNF STD
A351 GR Stellited CF8 A320 GRB8CL2 A194 GR 8 SPWD, SS304, CAF, I & O Ring A182 GR SS 304 F304 A403 GR SS 304 WP304
On line SW CPLG <2” 3000# 0.75” pipe, Globe,
A403 GR SS 304 WP304W
BRANCH PIPE 1.5”
BRANCH CONNECTION TYPE SW, TEE, 3000#
0.5”
1.5”
24.0” 0.5”
1.5”
SW, Half Coupling, 3000#, except 2”X1.5” where Tee is used
10.0”
Pipe-to-Pipe connection except equal size branch connection where Equal Tee is used.
2.0”
PRESS CONN TEMP CONN
On line >1.5” 0.75” PIPE 1.5” PIPE 200 mm long
12.0” SW, SCH 80 NIPPLE, Globe FLG, Tapping on line 4.0” pipe (min)
24.0”
Pipe-to-Pipe connection with reinforcement pad except equal size branch connection where Equal Tee is used.
Fluid Service: Non-Corrosive Hydrocarbon Process (l/v/g), Kerosene, LPG (gas/oil), Fuel Oil/Gas, Crude Oil, Heavy Naphtha, Wash Water, Demulsified Solution, Ammonia Solution, Corrosion Inhibitor, Steam &Condensate (N-IBR).
PIPING CLASS B1A SN ITEM 1
PIPE
2
FLANGE
3
BLIND FLANGE SPACER SPCR
4 5
6
FITTING ALL
VALVE
PIPING SPECIFICATION
MATERIAL ANSI RATING 300#
DIAMETER RANGE 0.5” 1.5” 2.0” 6.0” 8.0” 18.0” 20.0” 24.0” 0.5” 1.5” 2.0” 24.0” 0.5” 24.0”
SCH./ Rating SCH 80 SCH 40 SCH 40 7.92MM 300# 300# 300#
FACE FINISH -
0.5” 18.0” 0.5” 2.0”
16.0” 24.0” 1.5” 14.0”
16.0”
24.0”
300# 300# 3000# PIPE SCH PIPE SCH
Corrosion Allowance 1.5 mm
MATERIAL
125 SF 125 SF 125 SF
DIMN. STD. B36.10 B36.10 B36.10 B36.10 B 16.5 B 16.5 B 16.5
125 SF 125 SF R = 1.5D
API 590 API 590 B16.11 B16.9
ASTM A105 ASTM A105 ASTM A105 ASTM A234 GR WPB
B16.9
ASTM WPBW
API 5L GR B API 5L GR B API 5L GR B API 5L GR B ASTM A105 ASTM A105 ASTM A105
BODY
A234
GR
TRIM
0.5”
1.5”
800#
-
API 602
2.0”
24.0”
300#
API 600
0.5”
1.5”
800#
125 SF -
2.0”
8.0”
300#
BS 1873
0.5”
1.5”
800#
125 SF -
2.0”
24.0”
300#
BS 1868
0.5”
24.0”
2 MM
125 SF -
0.5”
1.50”
800#
2.0”
14.0”
PIPE SCH
GATE
BS 5352
GLOBE
BS 5352
CHECK
7 8 9
STUDS NUTS GASKET RING STRAINER PERM
B18.2 B18.2 B16.21
Y MNF STD TYPE T MNF STD TYPE
ASTM A105
13% CR A216 GR 13% WCB CR ASTM A105 13% CR A216 GR 13% WCB CR ASTM A105 13% CR A216 GR 13% WCB CR A193 GR B7 A194 GR 2H SPWD,SS304 (CAF) ASTM A105 A234 WPB
16.0” 24.0” PIPE JOINT CONNECTION
&
GR SS 304
PIPE T MNF STD A234 SCH TYPE WPBW AUXILIARY BRANCH CONNECTIONS
ITEM
SIZE
DESCRIPTION RUN PIPE
BRANCH PIPE
MAINT JOINT
ALL
1.5”
0.5”
1.5”
PIPE JOINT
1.5”& below 2.0”& above
FLANGED 0.5” but keep minimum SW, CPLG, 2.0” 3000# BUTT WELD
24”
0.5”
1.5”
SS 304
GR SS 304
BRANCH CONNECTION TYPE SW, TEE, 3000#
SW, Half Coupling, 3000#, except 2”X1.5” where Tee is used
DRAIN
VENTS
PRESS CONN TEMP CONN
On line<2” On line >1.5” On line<2” On line >1.5” 0.75” PIPE 1.5” 200 long
SW CPLG 3000# 0.75” pipe, Globe,
2.0”
24”
SW CPLG 3000# 0.75” pipe, Globe,
SW, SCH 80 NIPPLE PIPE FLG, Tapping on mm line 4.0” pipe (min)
Pipe-to-Pipe connection with reinforcement pad except equal size branch connection where Equal Tee is used.
Fluid Service: Medium Pressure Steam (IBR), Boiler Feed Water (IBR)
PIPING PIPING CLASS SPECIFICATION B2A SN ITEM DIAMETER RANGE 1 PIPE 0.5” 1.5” SMLS 2.0” 6.0”
EFSW
2
FLANGE
3
BLIND FLANGE FIG-8 SPACER
4 5
FITTING
8.0”
14.0”
16.0”
18.0”
20.0”
24.0”
0.5” 2.0” 0.5”
1.5” 24.0” 24.0”
0.5” 18.0” 0.5” 2.0”
16.0” 24.0” 1.5” 14.0”
MATERIAL ANSI RATING 300#
Corrosion Allowance 1.5 mm MATERIAL
SCH./ Rating SCH 80 SCH 40
Face Finish -
DIMN. STD. B36.10
-
B36.10
A106 GR B
SCH 40 SCH 40 SCH XS 300# 300# 300#
-
B36.10
A106 GR B
B36.10
A672 GR C70 CL2
B36.10
A672 GR C70 CL2
125 SF B 16.5 125 SF B 16.5 125 SF B 16.5
300# 125 SF API 590 300# 125 SF API 590 3000# R=1.5D B16.11 PIPE B16.9 SCH
A106 GR B
ASTM A105 ASTM A105 ASTM A105 ASTM A105 ASTM A105 ASTM A105 ASTM A234 GR WPB
16.0” 6
VALVE GATE
24.0”
2.0”
24.0”
0.5”
1.5”
2.0”
8.0”
0.5”
1.5”
2.0”
24.0”
STEAM TRAP
0.5”
1.5”
STUDS
-
-
NUTS
-
-
GLOBE
CHECK
7
8 9
GASKET 0.5” RING STRAINER 0.5” PERM 2.0”
24.0” 1.50” 14.0”
16.0”
PIPE JOINT CONNECTION
&
24.0”
PIPE SCH
B16.9
ASTM A234 GR WPBW
BODY 300# 125 API 600 A216 SF WCB 800# BS 5352 ASTM A105 300# 125 BS 1873 A216 SF WCB 800# BS 5352 ASTM A105 300# 125 BS 1868 A216 SF WCB 300# 125 BS 1868 ASTM SF A105 B18.2 A193 B7 B18.2 A194 2H 5 MM API 601 SPWD, (CAF) 800# Y MNF STD ASTM TYPE A105 PIPE T MNF STD A234 SCH TYPE GR WPB
TRIM GR 13% CR 13% CR GR 13% CR 13% CR GR 13% CR 13% CR GR GR SS304 SS 304 SS 304
PIPE SCH
T MNF STD A234 SS 304 TYPE GR WPBW AUXILIARY BRANCH CONNECTIONS
ITEM
SIZE
DESCRIPTION RUN PIPE
BRANCH PIPE
MAINT
ALL
FLANGED
0.5”
0.5”
1.5”
1.5”
BRANCH CONNECTION TYPE SW, TEE, 3000#
JOINT PIPE JOINT
but keep minimum SW, CPLG, 2.0” 3000# BUTT WELD
1.5”& below 2.0”& above
DRAINS On line<2” On line>1.5” VENTS On line<2” On line>1.5” PRESS 0.75” CONN PIPE TEMP 1.5” CONN PIPE 200 mm long
24”
SW CPLG 3000# 0.75” pipe, Globe,
0.5”
1.5”
SW, Half Coupling, 3000#, except 2”X1.5” where Tee is used
2.0”
24”
Pipe-to-Pipe connection with reinforcement pad except equal size branch connection where Equal Tee is used.
SW CPLG 3000# 0.75” pipe, Globe, SW, SCH 80 NIPPLE, Globe FLG, Tapping on line 4.0” pipe (min)
Fluid Service: Non-corrosive Low Temperature Hydrocarbon (Liquid or Vapour)
PIPING CLASS B4A SN ITEM 1
2
PIPE SMLS
EFSW FLANGE
PIPING MATERIAL SPECIFICATION ANSI RATING 300# DIAMETER RANGE 0.5” 1.5” 2.0” 6.0” 8.0” 14.0” 16.0” 18.0”
SCH./ Rating SCH 80 SCH 40 SCH 30 SCH 30
20.0”
24.0”
12.7MM
0.5”
1.5”
300#
Face Finish -
DIMN. STD. B36.10 B36.10 B36.10 B36.10 B36.10
125 SF B 16.5
Corrosion Allowance 1.5 mm MATERIAL A333 GR 6 A333 GR 6 A333 GR 6 A671 GR CC70 CL32 A671 GR CC70 CL32 ASTM A350 GR LF2
3 4
BLIND FLANGE FIG-8
2.0”
24.0”
300#
125 SF B 16.5
0.5”
24.0”
300#
125 SF B 16.5
0.5”
16.0”
300#
125 SF API 590
18.0”
24.0”
300#
125 SF API 590
ASTM A350 GR LF2 ASTM A350 GR LF2 ASTM A350 GR LF2
SPACER
5
6
7
8 9
ASTM A350 GR LF2 FITTING 0.5” 1.5” 3000# R=1.5D B16.11 ASTM A350 GR LF2 ALL 2.0” 14.0” PIPE B16.9 ASTM A420 GR SCH WPL6 16.0” 24.0” PIPE B16.9 ASTM A420 GR SCH WPL6W VALVE BODY TRIM 0.5” 1.5” 800# API 602 A350 Stellited GATE GR LF2 2.0” 24.0” 300# 125 SF API 600 A352 Stellited GR LCB 0.5” 1.5” 800# BS 5352 A350 Stellited GR LF2 2.0” 8.0” 300# 125 SF BS 1873 A352 Stellited GR LCB GLOBE 0.5” 1.5” 800# BS 5352 A350 Stellited GR LF2 2.0” 24.0” 300# 125 SF BS 1868 A352 Stellited GR LCB CHECK STUDS B18.2 A320 GR L7 NUTS B18.2 A194 GR 4 GASKET 0.5” 24.0” 5 MM API 601 SPWD, SS304 (CAF) RING STRAINER 0.5” 1.50” 800# Y TYPE MNF A350 GR LF2 SS STD 304 PERM
2.0”
14.0”
PIPE T TYPE MNF A420 SCH STD WPL6 16.0” 24.0” PIPE T TYPE MNF A420 SCH STD WPL6W PIPE JOINT & AUXILIARY BRANCH CONNECTIONS CONNECTION ITEM
SIZE
DESCRIPTION RUN PIPE
MAINT JOINT
ALL
PIPE JOINT
1.5”& below 2.0”& above On line <2” On line >1.5” On line<2” On line >1.5” 0.75” PIPE 1.5” PIPE 200 mm long
FLANGED 0.5” but keep minimum SW, CPLG, 2.0” 3000# BUTT WELD
DRAIN
VENTS
PRESS CONN TEMP CONN
SW CPLG 3000# 0.75” pipe, Globe, SW CPLG 3000# 0.75” pipe, Globe, SW, SCH 80 NIPPLE, Globe FLG, Tapping on line 4.0” pipe (min)
GR SS 304 GR SS 304
1.5”
BRANCH BRANCH PIPE CONNECTION TYPE 0.5” 1.5” SW, TEE, 3000#
24”
0.5”
1.5” SW, Half Coupling, 3000#, except 2”X1.5” where Tee is used
2.0”
24” Pipe-to-Pipe connection with reinforcement pad except equal size branch connection where Equal Tee is used.
Fluid Service: Medium Pressure High Temperature Non-corrosive Hydrocarbon (Liquid or vapour), Mild to Moderate Corrosive Hydrocarbon, flammable, nonlethal, Fuel Gas, Valve Residue, BIM Reactor Effluents.
PIPING CLASS PIPING
MATERIAL ANSI RATING
Corrosion
B1D
SPECIFICATION
SN ITEM
DIAMETER RANGE 0.5” 1.5”
SCH./ FACE Rating FINISH SCH 80
DIMN. STD.
Allowance 1.5 mm MATERIAL
B36.10
A335 GR P11
2.0”
6.0”
-
B36.10
A335 GR P11
8.0”
10”
SCH 40 SCH 30
-
B36.10
A335 GR P11
EFSW
12”
24”
XS
B36.10
A335 GR P11
FLANGE
0.5”
1.5”
300#
125 SF
2.0”
24”
300#
125 SF
0.5”
24”
300#
125 SF
0.5”
16”
300#
125 SF
18.0”
24.0” 300#
125 SF
0.5”
1.5”
2.0”
14.0” PIPE SCH
16.0”
24.0” PIPE SCH
0.5”
1.5”
800#
-
2.0”
24.0”
300#
125 SF
0.5”
1.5”
800#
-
2.0”
8.0”
300#
125 SF
1
2
3 4
5
6
PIPE SMLS
BLIND FLANGE SPACER OR FIG-8
FITTING
300#
3000# R=1.5D
VALVE Gate
Globe
B 16.5
ASTM A182 GR F11 B 16.5 ASTM A182 GR F11 B 16.5 ASTM A182 GR F11 API 590 ASTM A182 GR F11 API 590 ASTM A182 GR F11 B16.11 ASTM A182 GR F11 B16.9 ASTM A234 GR WP11 CL1 B16.9 ASTM A234 GR WP11 CL1 BODY TRIM API A182 GR Stellited 602 F11 API A217 GR Stellited 600 WC6 BS A182 GR Stellited 5352 F11 BS
A217
GR Stellited
Check 0.5”
1.5”
800#
-
2.0”
24.0”
300#
125 SF
7
STUDS
-
-
-
-
8
NUTS GASKET
0.5”
24.0”
5 MM
-
9
STRAINER 0.5”
1.50”
800#
Y TYPE
2.0”
14.0”
PIPE SCH
T TYPE
16.0”
24.0”
PIPE SCH
T TYPE
PIPE JOINT CONNECTION
&
1873 BS 5352 BS 1868
WC6 A182 F11 A217 WC6
GR Stellited
B18.2
A193 GR B16 B18.2 A194 GR 4 B16.21 SPWD, SS304, CAF, I & O ring
MNF STD MNF STD
MNF STD
A182 SS 304 GR F11 A234 SS 304 GR WP11 CL1 A234 SS 304 GR WP11W CL1
AUXILIARY BRANCH CONNECTIONS
ITEM
SIZE
DESCRIPTION RUN PIPE BRANCH PIPE
MAINT JOINT
ALL
PIPE JOINT
FLANGED 0.5” but keep minimum SW, CPLG, 2.0” 3000# BUTT WELD
1.5”& below 2.0”& above On line SW CPLG 3000# 0.75” <2” pipe, Globe On line>1.5”
DRAIN
GR Stellited
1.5” 0.5” 1.5”
24”
BRANCH CONNECTION TYPE SW, TEE, 3000#
0.5” 1.5”
SW, Half Coupling, 3000#, except 2”X1.5” where Tee is used
2.0” 24”
Pipe-to-Pipe connection with
VENTS
PRESS CONN TEMP CONN
On line<2” On line>1.5” 0.75” PIPE 1.5” PIPE 200 mm long
reinforcement pad except equal size branch connection where Equal Tee is used.
SW CPLG 3000# 0.75” pipe, Globe,
SW, SCH 80 NIPPLE, Globe FLG, Tapping on line 4.0” pipe (min)
Fluid Service: Non-corrosive Medium pressure & Low Temperature Hydrocarbon (Liquid or Vapour)
PIPING CLASS PIPING SPECIFICATION B1H
MATERIAL ANSI RATING 300#
SN ITEM
DIAMETER RANGE
1
0.5”
1.5”
2.0”
6.0”
PIPE SMLS
8.0” 12.0”
SCH./ Face Finish DIMN. Rating STD. SCH B36.10 80
SCH 40 10.0” SCH 30 16.0” SCH STD
Corrosion Allowance 1.5 mm MATERIAL A333 GR 3
-
B36.10
A333 GR 3
-
B36.10
A333 GR 3
-
B36.10
A333 GR 3
2
3 4
5
EFSW FLANGE
BLIND FLANGE SPACER OR FIG-8
FITTING
16.0”
24.0” XS
0.5”
1.5”
300#
125 SF
2.0”
24.0” 300#
125 SF
0.5”
24.0” 300#
125 SF
0.5”
16.0” 300#
125 SF
18.0”
24.0” 300#
125 SF
0.5”
1.5”
2.0”
14.0” PIPE SCH 24.0” PIPE SCH
16.0” 6
B36.10
3000# R=1.5D
VALVE
A671 GR CF66 CL32
B 16.5
ASTM A350 GR LF3 B 16.5 ASTM A350 GR LF3 B 16.5 ASTM A350 GR LF3 API 590 ASTM A350 GR LF3 API 590 ASTM A350 GR LF3 B16.11 ASTM A350 GR LF3 B16.9 ASTM A420 GR WPL3 B16.9 ASTM A420 GR WPL3W BODY TRIM
GATE
GLOBE
0.5”
1.5”
800#
-
2.0”
24.0” 300#
125 SF
0.5”
1.5”
800#
-
2.0”
8.0”
300#
125 SF
0.5”
1.5”
800#
-
2.0”
24.0” 300#
125 SF
-
-
-
CHECK
7
STUDS
-
API 602 A350 GR LF3 API 600 A352 GR LC3 BS 5352 A350 GR LF3 BS 1873 A352 GR LC3 BS 5352 A350 GR LF3 BS 1868 A352 GR LC3 B18.2 A320
Stellited
Stellited
Stellited
Stellited
Stellited
Stellited
NUTS 8 9
-
-
GASKET 0.5” RING STRAINER 0.5” PERM 2.0”
16.0”
PIPE JOINT CONNECTION ITEM
SIZE
MAINT ALL JOINT
PIPE JOINT
&
-
-
B18.2
24.0” 5 MM
-
B16.21
1.50” 800#
Y TYPE
14.0” PIPE SCH
T TYPE
MNF STD MNF STD
24.0” PIPE SCH
T TYPE
MNF STD
GR L7 A194 GR 4 SPWD, SS304, CAF, I & O ring A350 GR SS LF3 304 ASTM SS A420 GR 304 WPL3 ASTM SS A420 GR 304 WPL3W
AUXILIARY BRANCH CONNECTIONS DESCRIPTION RUN PIPE
BRANCH PIPE
FLANGED 0.5” 1.5” 0.5” but keep minimum
1.5”& below SW, CPLG, 2.0” 24” 2.0”& above 3000# BUTT WELD DRAIN On line SW CPLG 3000# 0.75” <2” pipe, Globe, On line>1.5” VENTS On line<2” SW CPLG 3000# 0.75” On line>1.5” pipe, Globe, PRESS 0.75” PIPE SW, SCH 80 CONN NIPPLE, Globe TEMP 1.5” PIPE 200 FLG, Tapping on CONN mm long line 4.0” pipe (min)
BRANCH CONNECTION TYPE
1.5”
SW, TEE, 3000#
0.5”
1.5”
SW, Half Coupling, 3000#, except 2”X1.5” where Tee is used
2.0”
24.0” Pipe-to-Pipe connection with reinforcement pad except equal size branch connection where Equal Tee is used.
Fluid Service: Medium Pressure Pure Process (liquid or Vapour), Mild corrosive
hydrocarbon Flammable, Non-flammable & lethal’ DM Water, Polished water, chemicals and High Pressure Fuel Gas PIPING CLASS B1K SN ITEM 1
PIPE
2
FLANGE
3
BLIND FLANGE
4
FIG-8
5
SPACER FITTING
6
VALVE
PIPING SPECIFICATION
MATERIAL ANSI RATING 300#
CORROSION ALLOWANCE: NIL
DIAMETER RANGE 0.5” 1.5” 2.0” 4.0” 6.0” 8.0” 10.0” 12”
SCH./ Rating Face Finish SCH 40S SCH 10S 6.35MM 7.92MM -
DIMN. STD. B36.10 B36.10 B36.10 B36.10
MATERIAL
14.0” 24”
11.1MM
-
B36.10
0.5” 2.0” 0.5”
1.5” 24” 24”
300# 300# 300#
125 SF B 16.5 125 SF B 16.5 125 SF B 16.5
0.5” 16” 18.0” 24”
300# 300#
125 SF API 590 A182 GR F304 125 SF API 590 A182 GR F304
0.5” 1.5” 2.0” 14” 16.0” 24”
3000# PIPE SCH PIPE SCH
R=1.5D B16.11 B16.9 B16.9
0.5”
1.5”
800#
2.0” 0.5”
A312 GR TP304 A312 GR TP304 A312 GR TP304 A358 GR TP304 CL1 A358 GR TP304 CL1 A182 GR F304 A182 GR F304 A182 GR F304
A182 GR F304 A403 GR WP304 A403 GR WP304W BODY TRIM
GATE -
API 602
A182 Stellited GR F304
24.0” 300#
125 SF
1.5”
-
API 600 BS 5352
A351 Stellited GR CF8 A182 Stellited GR F304
GLOBE
CHECK
800#
2.0”
8.0”
300#
125 SF
BS 1873 BS 5352 BS 1868 B18.2
A351 Stellited GR CF8 0.5” 1.5” 800# A182 Stellited GR F304 2.0” 24” 300# 125 SF A351 Stellited GR CF8 7 STUDS A320 GR B8 CL2 NUTS B18.2 A194 GR 8 8 GASKET 0.5” 24.0” 5 MM B16.21 SPWD, SS304, CAF, I & O ring RING 9 STRAINER 0.5” 1.50” 800# Y TYPE MNF A182 GR SS STD F304 304 PERM 2.0” 14.0” PIPE SCH T TYPE MNF A403 GR SS STD WP304 304 16” 24.0” PIPE SCH T TYPE MNF A403 GR SS STD WP304W 304 PIPE JOINT & AUXILIARY BRANCH CONNECTIONS CONNECTION ITEM
SIZE
DESCRIPTION RUN PIPE
MAINT JOINT
ALL
FLANGED 0.5” but keep minimum
1.5”
BRANCH BRANCH PIPE CONNECTION TYPE 0.5” 1.5” SW, TEE, 3000#
PIPE JOINT
1.5”& below 2.0”& above On line<2”
SW, CPLG, 2.0” 3000# BUTT WELD SW CPLG 3000# 0.75” pipe, Globe,
24”
0.5”
1.5” SW, Half Coupling, 3000#, except 2”X1.5” where Tee is used
2.0”
24” Pipe-to-Pipe connection with reinforcement
DRAIN
On line>1.5”
VENTS
PRESS CONN TEMP CONN
On line<2” On line>1.5” 0.75” PIPE
SW CPLG 3000# 0.75” pipe, Globe,
pad except equal size branch connection where Equal Tee is used.
SW, SCH 80 NIPPLE, Globe 1.5” PIPE FLG, Tapping on 200 mm long line 4.0” pipe (min)
Fluid Service: Non-Corrosive Hydrocarbon Process (l/v/g), Kerosene, LPG (gas/oil), Fuel Oil/Gas, Crude Oil, Heavy Naphtha, Wash Water, Demulsified Solution, Steam &Condensate (N-IBR). PIPING CLASS D1A SN ITEM 1
2
3 4
5
PIPE SMLS
EFSW FLANGE
BLIND FLANGE FIG-8 SPACER FITTING
PIPING SPECIFICATION DIAMETER RANGE 0.5” 1.5” 2.0” 6.0” 8.0” 10.0” 12.0” 14.0” 16.0” 18.0”
MATERIAL ANSI RATING 600# SCH./ FACE DIMN. Rating FINISH STD. SCH 80 B36.10 SCH 80 B36.10 SCH 60 B36.10 SCH XS B36.10 14.0MM B36.10
CORROSION ALLOWANCE: 1.5 MM MATERIAL
0.5”
1.5”
600#
125 SF
B 16.5
ASTM A105
2.0” 0.5”
24.0” 24.0”
600# 600#
125 SF 125 SF
B 16.5 B 16.5
ASTM A105 ASTM A105
0.5” 10.0”
8.0” 24.0”
600# 600#
125 SF 125 SF
API 590 API 590
ASTM A105 ASTM A105
0.5” 2.0”
1.5” 14.0”
3000# PIPE
R=1.5D B16.11 B16.9
API 5L GR B API 5L GR B API 5L GR B API 5L GR B A672 GRC70CL12
ASTM A105 ASTM A234 GR
SCH PIPE SCH
WPB 16.0” 24.0” B16.9 ASTM A234 GR WPBW 6 VALVE BODY TRIM GATE 2.0” 24.0” 600# 125 API 600 A216 13% CR SF GR WCB GLOBE 0.5” 1.5” 800# BS 5352 ASTM 13% CR A105 2.0” 8.0” 600# 125 BS 1873 A216 13% CR SF GR WCB CHECK 0.5” 1.5” 800# BS 5352 ASTM 13% CR A105 2.0” 24.0” 600# 125 BS 1868 A216 13% CR SF GR WCB 7 STUDS B18.2 A193 GR B7 NUTS B18.2 A194 GR 2H 8 GASKET 0.5” 24.0” 5 MM B16.21 SPWD, SS304, CAF, O Ring 9 STRAINER 0.5” 1.50” 800# Y MNF STD ASTM SS 304 TYPE A105 2.0” 14.0” PIPE SCH T MNF STD A234 SS 304 TYPE GR WPB 16.0” 24.0” PIPE SCH T MNF STD A234 SS 304 TYPE GR WPBW PIPE JOINT & AUXILIARY BRANCH CONNECTIONS CONNECTION
ITEM
SIZE
DESCRIPTION
RUN PIPE
BRANCH PIPE
BRANCH CONNECTION TYPE
MAINT JOINT PIPE JOINT
DRAIN
VENTS
PRESS CONN TEMP CONN
ALL
FLANGED 0.5” but keep minimum SW, CPLG, 3000# BUTT WELD
1.5”
0.5”
1.5” SW, TEE, 3000#
2.0”
24”
0.5”
1.5” SW, Half Coupling, 3000#, except 2”X1.5” where Tee is used 24” Pipe-to-Pipe connection with reinforcement pad except equal size branch connection where Equal Tee is used.
1.5”& below 2.0”& above On line SW CPLG 3000# <2”
On line >1.5” On line<2” On line>1.5” 0.75” PIPE 1.5” PIPE 200 mm long
BUTT WELDED
2.0”
SW CPLG 3000# BUTT WELDED SW, SCH 80 NIPPLE FLG, Tapping on line 4.0” pipe (min)
Fluid Service: Steam and Boiler Feed Water (IBR) up to 400 0 C
PIPING CLASS D2A SN ITEM 1
PIPE
2
FLANGE
3
BLIND
PIPING SPECIFICATION
MATERIAL ANSI RATING 600#
CORROSION ALLOWANCE: 1.5 MM
DIAMETER RANGE 0.5” 1.5” 2.0” 6.0” 8.0” 14.0” 16.0” 24.0”
SCH./ Rating SCH 80 SCH 80 SCH 60 SCH 40
Face Finish -
DIMN. STD. MATERIAL B36.10 B36.10 B36.10 B36.10
A106 GR B A106 GR B A106 GR B A672 GR C70 CL2
0.5” 2.0” 0.5”
600# 600# 600#
125 SF 125 SF 125 SF
B 16.5 B 16.5 B 16.5
ASTM A105 ASTM A105 ASTM A105
1.5” 24.0” 24.0”
FLANGE
4
FIG-8
0.5” 8.0” 10.0” 24.0”
600# 600#
125 SF 125 SF
API 590 API 590
0.5” 2.0”
3000# PIPE SCH PIPE SCH
R=1.5D B16.11 B16.9
ASTM A105 ASTM A105
SPACER 5
FITTING
1.5” 14.0”
16.0” 24.0” 6
VALVE 2.0”
24.0”
600#
0.5” 2.0”
1.5” 8.0”
800# 300#
0.5” 2.0”
1.5” 24.0”
800# 600#
0.5”
1.5”
600#
0.5” 0.5”
24.0” 1.50”
5 MM 800#
GATE
GLOBE
7
B16.9
CHECK STUDS NUTS GASKET STRAINER
125 SF 125 SF 125 SF 125 SF
API 600
Y TYPE T TYPE
B18.2 B18.2 API 601 MNF STD
BS 5352 BS 1873 BS 5352 BS 1868 BS 1868
ASTM A105 ASTM A234 G WPB ASTM A234 G WPBW BODY TRIM A216 GR 13% CR WCB ASTM A105 13% CR A216 GR 13% CR WCB ASTM A105 13% CR A216 GR 13% CR WCB ASTM A105 13% CR
A193 GR B7 A194 GR 2H 8 SPWD, SS304 (CAF) 9 ASTM SS 304 A105 2.0” 14.0” PIPE MNF STD A234 SS 304 SCH GR WPB 16.0” 24.0” PIPE T MNF STD A234 SS 304 SCH TYPE GR WPBW PIPE JOINT & AUXILIARY BRANCH CONNECTIONS CONNECTION
ITEM
SIZE
MAINT JOINT
ALL
PIPE JOINT DRAIN
VENTS
PRESS CONN TEMP CONN
DESCRIPTION RUN PIPE
FLANGED 0.5” but keep minimum 1.5”& below SW, CPLG, 2.0” 2.0”& above 3000# BUTT WELD On line <2” SW CPLG 3000# 0.75” On line>1.5” pipe, Globe, On line<2” SW CPLG 3000# 0.75” On line>1.5” pipe, Globe, 0.75” PIPE SW, SCH 80 NIPPLE, Globe 1.5” PIPE 200 FLG, Tapping on mm long line 4.0” pipe (min)
BRANCH PIPE
1.5”
0.5”
1.5”
24”
0.5”
1.5”
2.0”
24”
BRANCH CONNECTIO TYPE SW, TEE, 3000
SW, Ha Coupling, 3000#, exce 2”X1.5” whe Tee is used Pipe-to-Pipe connection wi reinforcement pad except equ size branc connection where Equal Te is used.
Fluid Service: Non-corrosive High Temperature Hydrocarbon (Liquid or Vapour)
PIPING CLASS D1D SN ITEM 1
PIPE SMLS
PIPING MATERIAL SPECIFICATION
DIAMETER RANGE
ANSI RATING 600#
0.5”
1.5”
SCH./ FACE DIMN. Rating FINISH STD. XS B36.10
2.0”
6.0”
XS
-
B36.10
CORROSION ALLOWANCE: 1.5 MM MATERIAL A335 GR P11 A335 GR P11
2
3 4
5
8.0”
14.0” SCH 80
-
B36.10
A335 GR P11
EFSW
16.0”
18.0” 20 MM -
B36.10
A691 GR 1.25CR CL42
FLANGE
0.5”
1.5”
600#
125 SF
B 16.5
ASTM A182 GR F11
2.0”
24.0” 600#
125 SF
B 16.5
BLIND FLANGE FIG-8
0.5”
24.0” 600#
125 SF
B 16.5
0.5”
8.0”
600#
125 SF
API 590
SPACER
10.0”
20.0” 600#
125SF
API 590
FITTING
0.5”
1.5”
R=1.5D B16.11
2.0”
14.0” PIPE SCH 24.0” PIPE SCH
ASTM A182 GR F11 ASTM A182 GR F11 ASTM A182 GR F11 ASTM A182 GR F11 ASTM A182 GR F11 ASTM A234 GR WP11 CL1 ASTM A234 GR WP11 CL1 BODY TRIM A217 Stellited GR WC6 A182 Stellited GR F11 A217 Stellited GR WC6
16.0” 6
3000#
B16.9 B16.9
VALVE 2.0”
24.0” 600#
125 SF
API 600
0.5”
1.5”
800#
-
BS 5352
2.0”
8.0”
600#
125 SF
BS 1873
0.5”
1.5”
800#
-
2.0”
24.0” 600#
BS 5352 A182 Stellited GR F11 BS 1868 A217 Stellited GR WC6
GATE
GLOBE
CHECK
125 SF
7
STUDS
-
-
-
-
B18.2
NUTS
-
-
-
-
B18.2
8
GASKET
0.5”
24.0” 5MM
-
B16.21
9
STRAINER 0.5”
1.50” 800#
Y TYPE MNF STD
2.0”
14.0” PIPE SCH
T TYPE MNF STD
16.0”
PIPE JOINT CONNECTION ITEM
SIZE
MAINT ALL JOINT
&
A193 GR B16 A194 GR 4 SPWD, SS304, GRAFOIL, I & O Ring A182 SS 304 GR F11
A234 SS 304 GR WP11 CL1 24.0” PIPE T TYPE MNF A234 SS 304 SCH STD GR WP11W CL1 AUXILIARY BRANCH CONNECTIONS DESCRIPTION RUN PIPE
FLANGED 0.5” but keep minimum PIPE 1.5”& below SW, CPLG, 2.0” JOINT 2.0”& above 3000# BUTT WELD DRAIN On line<2” SW CPLG 3000# 0.75” On line>1.5” pipe, Globe, VENTS On line<2” SW CPLG 3000# 0.75” On line>1.5” pipe, Globe, PRESS 0.75” PIPE SW, SCH 80 CONN NIPPLE, Globe TEMP 1.5” PIPE 200mm FLG, Tapping on CONN long line 4.0” pipe (min)
1.5”
24”
BRANCH BRANCH PIPE CONNECTION TYPE 0.5” 1.5” SW, TEE, 3000#
0.5” 1.5” SW, Half Coupling, 3000#, except 2”X1.5” where Tee is used 2.0” 24” Pipe-to-Pipe connection with reinforcement pad except equal size branch connection where Equal Tee is used.
Fluid Service: Non-corrosive Low Temperature & Medium Pressure Hydrocarbon (Liquid or Vapour)
PIPING CLASS PIPING SPECIFICATION D1H SN ITEM
DIAMETER RANGE
1
PIPE
0.5” 2.0” 8.0” 16.0”
2
FLANGE
3 4
5
BLIND FLANGE FIG-8
SPACER FITTING
MATERIAL ANSI RATING 600# SCH./ Rating
Face Finish
DIMN. STD.
1.5” 6.0” 14.0” 24.0”
SCH 80 SCH 80 SCH 60 SCH 60
-
B36.10 B36.10 B36.10 B36.10
0.5”
1.5”
300#
125 SF B 16.5
2.0”
24.0” 300#
125 SF B 16.5
0.5”
24.0” 300#
125 SF B 16.5
0.5”
8.0”
300#
125 SF API 590
10.0”
24.0” 300#
125 SF API 590
0.5”
1.5”
R=1.5D B16.11
3000#
CORROSION ALLOWANCE: 1.5 MM MATERIAL A333 GR 3 A333 GR 3 A333 GR 3 A671 GR CF66 CL32 ASTM A350 GR LF3 ASTM A350 GR LF3 ASTM A350 GR LF3 ASTM A350 GR LF3 ASTM A350 GR LF3 ASTM A350 GR
ALL
6
2.0”
14.0” PIPE SCH
B16.9
16.0”
24.0” PIPE SCH
B16.9
0.5”
1.5”
2.0”
24.0” 300#
125 SF
0.5”
1.5”
800#
-
2.0”
8.0”
300#
125 SF
0.5”
1.5”
800#
-
2.0”
24.0” 300#
0.5”
24.0” 5MM
0.5”
1.50” 800#
VALVE
LF3 ASTM A420 GR WPL3 ASTM A420 GR WPL3W BODY TRIM
GATE
GLOBE
CHECK
7 8 9
STUDS NUTS GASKET RING STRAINER PERM
800#
-
API 602
A350 LF3 API 600 A352 LC3 BS 5352 A350 LF3 BS 1873 A352 LC3 BS 5352 A350 LF3
GR Stellited GR Stellited GR Stellited
BS 1868 A352 GR Stellited LC3 B18.2 A320 GR L7 B18.2 A194 GR 4 B16.21 SPWD, SS304, CAF, I & O Ring Y TYPE MNF STD A350 GR SS LF3 304
14.0” PIPE T TYPE MNF STD SCH 16.0” 24.0” PIPE T TYPE MNF STD SCH PIPE JOINT & AUXILIARY BRANCH CONNECTIONS CONNECTION SIZE
GR Stellited
125 SF
2.0”
ITEM
GR Stellited
DESCRIPTION RUN PIPE
ASTM A420 GR WPL3 ASTM A420 GR WPL3W
SS 304 SS 304
BRANCH PIPE BRANCH CONNECTION
MAINT JOINT PIPE JOINT
DRAIN
VENTS
PRESS CONN TEMP CONN
ALL 1.5”& below 2.0”& above Line <2” Line>1.5” Line<2”
FLANGED 0.5” (Minimum) SW, CPLG, 2.0” 3000# BUTT WELD
1.5”
0.5”
1.5”
SW, TEE, 3000#
24”
0.5”
1.5”
SW, Half Coupling, 3000#, except 2”X1.5” where Tee is used
2.0”
24”
Pipe-to-Pipe connection with reinforcement pad except equal size branch connection where Equal Tee is used.
SW CPLG 3000# 0.75” pipe, Globe,
SW CPLG 3000# pipe, Line>1.5” 0.75” Globe, 0.75” SW, SCH 80 PIPE NIPPLE, Globe 1.5” PIPE FLG, Tapping on 200mm line 4.0” pipe long (min)
Fluid Service: Non-corrosive Medium Pressure & High Temperature Hydrocarbon (Liquid or Vapour), Medium corrosive Hydrocarbon (Liquid or Vapour) PIPING CLASS D2K
PIPING SPECIFICATION
SN ITEM
DIAMETER RANGE
1
0.5”
1.5”
2.0”
4.0”
6.0”
8.0”
EFSW
10.0”
12.0”
FLANGE
0.5” 2.0”
2
PIPE SMLS
MATERIAL ANSI RATING 600#
CORROSION ALLOWANCE: NIL
SCH./ Rating SCH 40S SCH 40S
Face DIMN. Finish STD. B36.10
MATERIAL
-
B36.10
A312 GR TP304
-
B36.10
A312 GR TP304
-
B36.10
1.5”
SCH 80S SCH 80S 600#
B 16.5
24.0”
600#
125 SF 125
A358 GR TP304 CL1 A182 GR F304
B 16.5
A182 GR F304
A312 GR TP304
3
BLIND FLANGE
0.5”
24.0”
600#
4
FIG-8 SPACER
0.5”
8.0”
600#
10.0”
12.0”
0.5” 2.0”
1.5” 8.0”
10.0”
12.0”
5
6
FITTING ALL
125 SF 600# 125 SF 3000# R = PIPE 1.5D SCH PIPE SCH
VALVE GATE
2.0”
24.0”
600#
GLOBE
0.5”
1.5”
800#
2.0”
8.0”
600#
0.5”
1.5”
800#
2.0”
24.0”
STUDS
-
-
NUTS
-
-
8
GASKET
0.5”
24.0”
9
STRAINER 0.5”
1.50”
2.0”
12.0”
CHECK
7
SF 125 SF
B 16.5
A182 GR F304
API 590
A182 GR F304
API 590
A182 GR F304
B16.11 B16.9
A182 GR F304 A403 GR WP304
B16.9
A403 GR WP304W
125 SF -
API 600
125 SF -
BS 1873
600#
125 SF
BS 1868
-
-
B18.2
BS 5352
BS 5352
BODY A351 GR CF8 A182 GR F304 A351 GR CF8 A182 GR F304 A351 GR CF8
TRIM Stellited Stellited Stellited Stellited Stellited
A320 GRB8CL2 B18.2 A194 GR 8 5MM B16.21 SPWD, SS304, CAF, I & O Ring 800# Y MNF A182 SS 304 TYPE STD GR F304 PIPE SCH
T MNF TYPE STD
A403 GR WP304
SS 304
PIPE JOINT CONNECTION ITEM SIZE
&
MAINT JOINT
ALL
PIPE JOINT
1.5”& below 2.0”& above On line <2” On line >1.5” On line <2” On line>1.5” 0.75” PIPE 1.5” PIPE 200 mm long
DRAIN
VENTS
PRESS CONN TEMP CONN
AUXILIARY BRANCH CONNECTIONS DESCRIPTION RUN PIPE
BRANCH PIPE
FLANGED 0.5” 1.5” but keep minimum SW, CPLG, 2.0” 24” 3000# BUTT WELD
0.5”
1.5”
0.5”
1.5”
SW, Half Coupling, 3000#, except 2”X1.5” where Tee is used
2.0”
12”
Pipe-to-Pipe connection with reinforcement pad except equal size branch connection where Equal Tee is used.
SW CPLG 3000# 0.75” pipe, Globe, SW CPLG 3000#; 0.75” pipe, Globe, SW, SCH 80 NIPPLE, Globe FLG, Tapping on line 4.0” pipe (min)
BRANCH CONNECTION TYPE SW, TEE, 3000#
Fluid Service: High Pressure Non-Corrosive Hydrocarbon Process (l/v/g), Non-Corrosive Hydrocarbon Process liquid, Kerosene, Crude Oil, Heavy Naphtha.
PIPING CLASS F1A SN ITEM
1
PIPE
PIPING SPECIFICATION
MATERIAL ANSI RATING 1500#
CORROSION ALLOWANCE: 1.5 MM
DIAMETER RANGE
SCH./ FACE DIMN. STD. Rating FINISH
MATERIAL
0.5”
1.5”
2.0”
14.0”
SCH 160 SCH 160
-
B36.10
API 5L GR B
-
B36.10
API 5L GR B
2
FLANGE
3
BLIND FLANGE FIG-8 SPACER FITTING
4 5
6
VALVE GATE
16.0”
20.0”
0.5” 2.0” 0.5”
1.5” 20.0” 20.0”
0.5” 6.0” 0.5”
4.0” 20.0” 1.5”
2.0”
14.0”
16.0”
24.0”
2.0”
20.0”
0.5”
1.5”
2.0”
8.0”
0.5”
1.5”
2.0”
20.0”
STUDS
-
NUTS 8
GASKET
9
-
B36.10
63 SF 63 SF 63 SF
B 16.5 B 16.5 B 16.5
1500# 1500# PIPE SCH PIPE SCH PIPE SCH
63 SF API 590 63 SF API 590 R = B16.11 1.5D B16.9 B16.9
-
PIPE SCH PIPE SCH PIPE SCH PIPE SCH PIPE SCH -
-
B18.2
-
-
-
-
B18.2
0.5”
24.0”
5MM
-
B16.21
STRAINER 0.5”
1.50”
1500# Y TYPE
MNF STD
2.0”
14.0”
PIPE SCH
MNF STD
GLOBE
CHECK
7
SCH 160 1500# 1500# 1500#
API 600 BS 5352 BS 1873 BS 5352 BS 1868
T TYPE
A672 GR C70 CL12 ASTM A105 ASTM A105 ASTM A105 ASTM A105 ASTM A105 ASTM A105 ASTM A234 GR WPB ASTM A234 GR WPBW BODY TRIM A216 GR Stellited WCB ASTM Stellited A105 A216 GR Stellited WCB ASTM Stellited A105 A216 GR Stellited WCB A193 GR B7
A194 GR 2H SOFT IRON (90BHN) max ASTM A105 A234 GR
SS 304 SS 304
WPB
16.0” 20.0”
PIPE JOINT CONNECTION
&
PIPE SCH
T TYPE
MNF STD
A234 GR WPBW AUXILIARY BRANCH CONNECTIONS
ITEM
SIZE
DESCRIPTION RUN PIPE BRANCH PIPE
MAINT JOINT
ALL
1.5”
0.5”
1.5”
PIPE JOINT
1.5”& below 2.0”& above On line<2”
FLANGED 0.5” but keep minimum BUTT WELD
Weldolet
20”
0.5”
1.5”
2.0”
20”
DRAIN
On BUTT line>1.5” WELDED
VENTS
On Weldolet line<2” On BUTT line>1.5” WELDED
PRESS CONN TEMP CONN
0.75” PIPE 1.5” PIPE 200 mm long
Weldolet FLG, Weldolet on line 4.0”NB (min)
2.0”
SS 304
BRANCH CONNECTION TYPE BW, TEE, 3000#
WELDOLET, PIPE SCH, except 2”X1.5” where Tee is used WELDOLET shall be used except equal size branch connection where Equal Tee is used.
Fluid Service: High Pressure & High Temperature Non-corrosive Hydrocarbon (Liquid or Vapour), High Pressure Boiler Feed Water and Superheated LP Steam (IBR). PIPING CLASS F2A SN ITEM 1
2 3 4
5
6
PIPE SMLS
EFSW FLANGE WN BLIND FLANGE FIG-8 SPACER
FITTING
PIPING SPECIFICATION DIAMETER RANGE 0.5” 1.5”
MATERIAL ANSI RATING 1500#
2.0”
14.0”
16.0”
20.0”
0.5” 2.0” 0.5”
1.5” 24.0” 24.0”
SCH./ Rating SCH 160 SCH 160 SCH 160 1500# 1500# 1500#
0.5”
8.0”
1500#
63 SF
10.0”
24.0”
1500#
63 SF
0.5”
1.5”
R= 1.5D
2.0”
14.0”
16.0”
20.0”
PIPE SCH PIPE SCH PIPE SCH
VALVE GATE
Corrosion Allowance: 1.5 mm
FACE DIMN. MATERIAL FINISH STD. B36.10 A106 GR B -
B36.10 A106 GR B
-
B36.10 A672 GR C70 CL2 B 16.5 ASTM A105 B 16.5 ASTM A105 B 16.5 ASTM A105
63 SF 63 SF 63 SF
API ASTM A105 590 API ASTM A105 590 B16.11 ASTM A105 B16.9
ASTM A234 GR WPB B16.9 ASTM A234 GR WPBW BODY TRIM
GLOBE 2.0”
20”
PIPE SCH
API 600
0.5”
1.5”
PIPE
BS
CHECK
A216 GR WCB ASTM
Stellited
Stellited
STEAM TRAP
SCH PIPE SCH
2.0”
8.0”
0.5”
1.5”
2.0”
20”
0.5”
1.5”
STUDS
-
-
-
-
NUTS
-
-
-
-
8
GASKET Oval Ring
0.5”
20”
9
STRAINER 0.5” PERM 2.0”
7
PIPE SCH PIPE SCH 1500#
63 SF
-
5352 A105 BS A216 Stellited 1873 GR WCB BS ASTM Stellited 5352 A105 BS A216 Stellited 1868 WCB MNF ASTM Stellited STD A105 B18.2 A193 GR B7 B18.2 A194 GR 2H B16.20 SOFT IRON (90BHN) max
1.50”
PIPE Y TYPE MNF ASTM SS SCH STD A105 304 14.0” PIPE T TYPE MNF A234 GR SS SCH STD WPB 304 16.0” 20” PIPE T TYPE MNF A234 GR SS SCH STD WPBW 304 PIPE JOINT & AUXILIARY BRANCH CONNECTIONS CONNECTION ITEM
SIZE
DESCRIPTION RUN PIPE
MAINT JOINT
ALL
PIPE JOINT
FLANGED 0.5” but keep minimum BUTT WELD 2.0”
1.5”& below 2.0”& above On Weldolet line<2” On line>1.5”
DRAIN
BRANCH PIPE
BRANCH CONNECTION TYPE BW, TEE, PIPE SCH.
1.5” 0.5”
1.5”
24” 0.5”
1.5”
WELDOLET, PIPE SCH., except 2”X1.5” where BW, Tee is used
2.0”
24”
WELDOLET shall be used
VENTS
PRESS CONN TEMP CONN
On line<2” On line>1.5” 0.75” PIPE 1.5” PIPE 200 mm long
except equal size branch connection where BW, Equal Tee is used.
Weldolet
Weldolet FLG, Weldolet on line 4.0”NB (min)
Fluid Service: High Pressure & High Temperature Non-corrosive Hydrocarbon (Liquid or Vapour) PIPING CLASS F2D SN ITEM 1
2 3 4
PIPE SMLS
EFSW FLANGE BLIND FLANGE FIG-8
PIPING MATERIAL ANSI RATING SPECIFICATION 1500# DIAMETER RANGE 0.5” 1.5” 2.0” 14.0” 16.0” 20.0”
0.5” 2.0” 0.5”
SCH./ Rating FACE FINISH SCH 160 SCH 160 SCH 160 -
CORROSION ALLOWANCE: MM
DIMN. STD.
MATERIAL
B36.10 B36.10 B36.10
A335 GR P11 A335 GR P11 A691 GR 1.25 CL42
1.5” 1500# 24.0” 1500# 24.0” 1500#
63 SF 63 SF 63 SF
B 16.5 B 16.5 B 16.5
ASTM A182 GRF11 ASTM A182 GRF11 ASTM A182 GRF11
0.5” 8.0” 1500# 10.0” 24.0” 1500#
63 SF 63 SF
API 590 API 590
ASTM A182 GRF11 ASTM A182 GRF11
0.5” 2.0”
R=1.5D B16.11 B16.9
SPACER 5
FITTING
1.5” PIPE SCH 14.0” PIPE SCH
16.0” 20.0” PIPE SCH 6
VALVE GATE
B16.9 BODY
ASTM A182 GRF11 ASTM A234 WP11CL1 ASTM A234 WP11CL1 TRIM
GLOBE
2.0”
20.0” PIPE SCH
0.5” 2.0” 0.5” 2.0” 0.5”
1.5” 8.0” 1.5” 20.0” 1.5”
PIPE SCH PIPE SCH PIPE SCH PIPE SCH 1500#
-
API 600
A217 GR WC6
Stellited
BS 5352 BS 1873 BS 5352 BS 1868 63 SF MNF STD
A182 GRF11 A217 GR WC6 A182 GRF11 A217 GR WC6 A182 GRF11
Stellited Stellited Stellited Stellited Stellited
-
B18.2 B18.2
A193 GR B16 A194 GR 4
-
B16.20
5CR, 1.5 MO (120BHN) max A182 GRF11
CHECK
STEAM TRAP
7
STUDS NUTS
-
-
8
GASKET Oval Ring
0.5”
20.0”
9
STRAINER 0.5”
1.50” PIPE SCH
Y MNF STD SS 304 TYPE 2.0” 14.0” PIPE SCH T MNF STD ASTM A234 GR SS 304 TYPE WP11CL1 16.0” 20.0” PIPE SCH T MNF STD ASTM A234 GR SS 304 TYPE WP11WCL1 PIPE JOINT & AUXILIARY BRANCH CONNECTIONS CONNECTION ITEM
SIZE
DESCRIPTION RUN PIPE
MAINT JOINT
ALL
PIPE JOINT
1.5”& below 2.0”& above
FLANGED 0.5” 1.5” but keep minimum BUTT WELD 2.0” 24”
BRANCH PIPE 0.5”
1.5”
0.5”
1.5”
BRANCH CONNECTIO TYPE BW, TEE, PI SCH.
WELDOLET, PIPE SC except 2”X1 where BW, T
DRAIN
VENTS
PRESS CONN TEMP CONN
is used
On line<2” Weldolet On line >1.5” On line <2”
2.0”
24.0”
Weldolet
WELDOLET shall be u except equal s branch connection where B Equal Tee used.
On line >1.5” 0.75” PIPE Weldolet 1.5” 200 long
PIPE FLG, Weldolet mm on line 4.0”NB (min)
Fluid Service: High Pressure & High Temperature medium corrosive Hydrocarbon (Liquid or Vapour)
PIPING CLASS F2K SN ITEM 1
2
3
PIPE SMLS
FLANGE
BLIND FLANGE
PIPING MATERIAL ANSI RATING SPECIFICATION 1500# DIAMETER RANGE 0.5” 1.5” 2.0” 3.0”
2.0” 4.0”
SCH./ Rating SCH 80S 8.74 11.10
0.5”
1.5”
1500#
63 SF
B 16.5
2.0”
4.0”
1500#
63 SF
B 16.5
0.5”
4.0”
1500#
63 SF
B 16.5
Corrosion Allowance NIL
Face Finish -
DIMN. STD. MATERIAL B36.19
A312 GR TP304
-
B36.19 B36.19
A312 GR TP304 A312 GR TP304
ASTM GRF304 ASTM GRF304 ASTM GRF304
A182 A182 A182
4
FIG-8
0.5”
4.0”
1500#
63 SF
API 590
0.5”
1.5”
R=1.5D B16.11
2.0”
4.0”
PIPE SCH PIPE SCH
ASTM GRF304
A182
SPACER 5
6
FITTING
VALVE GATE
2.0” 4.0”
GLOBE
0.5” 1.5” 2.0” 4.0”
CHECK 0.5” 1.5” 2.0” 4.0” 7 8
STUDS NUTS GASKET
0.5” 4.0”
9
STRAINER 1.50”
PIPE SCH PIPE SCH PIPE SCH PIPE SCH PIPE SCH -
B16.9
API 600 BS 5352 BS 1873 BS 5352 BS 1868 B18.2 B18.2 B16.20
-
ASTM A182 GRF304 ASTM A403 GR WP304
BODY TRIM A351 GR CF8 Stellited A182 Stellited GRF304 A351 GR CF8 Stellited A182 Stellited GRF304 A351 GR CF8 Stellited A193 GR B7 A194 GR 2H A182 GR F304 (130BHN) max A182 GR F304 SS 304
PIPE Y TYPE MNF SCH STD 4.0” PIPE T TYPE MNF A403 SCH STD WP304 PIPE JOINT & AUXILIARY BRANCH CONNECTIONS CONNECTION
GR SS 304
ITEM
SIZE
DESCRIPTION RUN PIPE
BRANCH PIPE
MAINT JOINT
ALL
1.5”
0.5”
1.5”
PIPE
1.5”&
FLANGE 0.5” but keep minimum BUTT WELD 2.0”
4.0”
0.5”
1.5”
BRANCH CONNECTION TYPE BW, TEE, PIPE SCH. WELDOLET,
JOINT
DRAIN
below 2.0”& above On line Weldolet <2” On line >1.5”
VENTS
On line Weldolet <2” On line >1.5”
PRESS CONN TEMP CONN
0.75” PIPE 1.5” PIPE 200 mm long
PIPE SCH., except 2”X1.5” where BW, Tee is used 2.0”
24”
WELDOLET shall be used except equal size branch connection where BW, Equal Tee is used.
Weldolet FLG, Weldolet on line 4.0”NB (min)
VALVE DESIGN Operating block valves shall be in accordance with the applicable P & ID and applicable specifications. A) Unless otherwise noted block valve in suction side of the pumps and compressors shall be of the line size regardless of pump or compressor nozzle size. B) Check and block valves in discharge side of pumps and compressors can be one size smaller, than line size, but never less than pump and compressor nozzle size. C) Generally all control valve sizes and there by pass and bleed valves are in accordance with the applicable P & Ids. D) Generally the primary block valves only are shown on P & Ids. For instrument connections to Process & Utility lines, vessels and equipment, instrument data sheets shall indicate the details of the valve requirements. E) Vent valves at high points & drains at low point shall be shown on the piping isometrics for line size 2” NB and above. For line size 1 ½” NB and below shall be decided in the field in accordance with the specification. F) Valves requiring gear operation shall be indicated on the applicable P & IDs. G) Gate valve shall be provided with pressure equalizing by-passes and globe type by-pass valves when the flow diagram indicates that a differential pressure approximately
equal to the pressure rating of the valve at the operating temperature may exist across the closed valves. Self-Contained Automatic Valves Self-contained automatic valves are used for pressure- reducing stations. The valve body itself is normally a globe-type valve. It is normally diaphragm actuated and hydraulically operated. The valves are capable of maintaining constant downstream pressure regardless of the fluctuations in the flow or upstream pressure by internal hydraulic controllers. Parts of the Valve: Body: Valve body is connected to pipe, fittings or vessels by their body ends, which may be flanged, screwed, butt or socket welding, or finished for hose, sleeve coupling. Jacketed valves are also available. Disc, Seat and Port: These components are directly used for stopping and regulating the flow. The moving part directly affecting the flow is termed as disc, regardless of its shape. The non-moving part is termed as the seat. The port is the maximum internal opening for flow when the valve is fully open. Discs may be actuated by conveyed fluid or be moved by stem having a linear, rotary or helical movement. The stem can be moved manually or be driven hydraulically, pneumatically or electrically, under remote or automatic control, or mechanically by weighted lever, springs etc. Stem: Stems are screwed. There are two types of screwed stems, the rising stem and non-rising stem. These are moved by hand-lever or hand-wheel. Rising Stem is provided, generally, for gate and globe valves. These are made either with inside screw (IS) or outside screw (OS). The OS type has a yoke on the bonnet and the assembly is referred to as Outside Screw and Yoke (OS& Y type). The handwheel can either rise with the stem, or the stem can rise through the hand wheel. Non-rising stem is provided in Gate valves. The hand wheel and the stem are in the same position, level-wise, whether the valve is open or closed. The screw is inside the bonnet and in contact with conveyed fluid. Depending on the size of the required valve and availabilities, selection of stem type can be based on (1) Whether it is undesirable for the conveyed fluid to be in contact with the thread bearing surface, (2) Whether an exposed screw is liable to be damaged by abrasive atmospheric dust or (3) Whether it is necessary to see whether the valve is open or closed. Most of the other valves have a simple rotary stem. Rotary, Ball, Plug, and Butterfly valves have a rotary stem that is moved by a permanent lever, or tool applied to a square boss at the end of the stem. Bonnet: There are three basic types of bonnets, such as: screwed (including union), bolted and breech lock. A screwed bonnet may occasionally stick and turn when a valve is opened or closed. Although sticking is less of a problem with the union type bonnet, valves with screwed bonnets are best reserved for services presenting no hazard to personnel. Union bonnets are more suitable for small valves requiring frequent dismantling than the simple screwed type. The bolted bonnet has largely displaced screwed and union bonnet valves in hydrocarbon applications. A U-bolt or clamp type bonnet is offered on some small gate valves for moderate pressures, to facilitate frequent cleaning and inspection. The pressure seal is a variation of bolted bonnet used for high-pressure valves, usually combined with OS & Y type construction. It makes use of line pressure to tighten and seal an internal metal ring or gasket against the body. A critical factor for valves used for process chemicals is the lubrication of the stem. Care needs to be taken for selection of packing, gland design and choice of lubricant. As an option the bonnet may include a Lantern Ring, which serves two purposes, either to act as a collection point to drain off any hazardous seepages, or as a point where lubricant can be injected. The breech lock is a heavier infrequently used and more expensive construction, also for high pressure use, and involves seal welding of the bonnet with the body. Seal: In most stems operated valves, irrespective of the stem has rotary or linear movement; packing
or seals are used between stem and bonnet or body. If high vacuum or corrosive, flammable or toxic fluid is to be handled, the disc or stem may be sealed by metal bellows, or by a flexible diaphragm. A gasket is used as seal between a bolted bonnet and valve body. Flanged valves use gaskets to seal against the line flanges. Butterfly valves may extend the resilient seat to also serve as line gaskets. The pressure-seal bonnet joint utilizes the pressure of conveyed fluids to tighten the seal. Type of Valve Operator: Operator is a device that opens or closes a valve. Different Types of Valve Operator are available as given below. Manual Operator: Manual operator is used where automatic control is not required. These valves may still result in good throttling control manually, if control is necessary. Gate, globe, and stop check valves are often supplied with hand wheel operators. Ball and butterfly valves are supplied with hand levers. Manual operators can be supplied with direct mount chain wheels or extensions to actuate valves in hard-to-reach locations, i.e. at height. Manual operators are much less expensive than automatic operators. Hand Lever: It is used to actuate the stems of small butterfly, ball, plug valves, and cocks. Wrench operation is used for cocks and small plug valves. Hand Wheel: It is the most common means of rotating the stem on the majority of popular smaller valves such as gate, globe and diaphragm. Hammer blow or impact hand wheels offer additional operating torque for gate and globe valves than normal hand wheels. Chain: It is used where a hand wheel would be out of reach for the operation. The stem is fitted with a chain wheel or wrench for lever operated valves and loop of the chain is brought down within reach of the operator, i.e. one meter of working floor level. Gear: These are used to reduce the operating torque. For manual operation, it consists of a hand wheel operated gear train actuating the valve stem. Generally, gear operators should be considered for valves of 350 mm NB and larger up to 300#, 200 mm NB and larger up to 600#, 150 mm NB and larger up to 1500# and 100 mm NB and larger for higher ratings. POWERED O PERATORS : FOLLOWINGS ARE THE POWER OPERATIONS PROVIDED ON THE VALVES : a. Electric Geared Motor: Geared Motor rotates the valve stem. This is useful for operating large size valves in remote areas. Electrical operators only require electrical power to the motors and electrical input signal from the controller in order to be positioned. Electrical operators are usually self-contained and operate within either a weatherproof or an explosion-proof casing. b. Solenoid: These can be used for fast acting check valves, and with on/off valves in light-duty instrumentation applications. c. Pneumatic and Hydraulic: These may be used where flammable vapour is likely to be present. A pneumatic operator can be a spring and diaphragm type or a pneumatic piston. Spring and diaphragm operators are pneumatically operated using low-pressure air supplied from a controller position or other source. The different type of operators include direct acting, in which increasing air pressure pushes down the diaphragm and extends the actuator stem; reverse acting, in which increasing air pressure pushes up the diaphragm and retracts the actuator stem; and direct acting for rotary valves. Pneumatic operators are simple, dependable, and economical. Moulded diaphragms can be used to provide linear performance and increase travel. The sizes of the operators are dictated by the output thrust required and available air pressure supply. Pneumatic piston operators are operated using highpressure air. The air pressure can be up to 1.03 MPa (150 psig), often eliminating the need for a pressure regulator that is required on a diaphragm actuator. The best design for piston actuators is double acting. This allows for the maximum force in both directions on the piston. Piston actuators
can be supplied with accessories that will position the valve in the event of loss of air supply. While these pneumatic operators are also available for rotary shaft valves, electrical operators tend to be more common on the rotary valves. They are of following forms: - Cylinder with double acting piston driven by air, water, oil or other liquid, which usually actuates the stem directly. - Air motor, which actuates the stem through gearing. These motors are commonly piston and cylinder radial type. - A double acting vane with limited rotary movement in a sector casing, actuating the stem directly. - Squeeze type. In addition, the amount of valve leakage is determined based on acceptability to process and design requirements. Control valve seats are classified in accordance with ANSI/FCI 70-2 for leakage. These classifications are summarized in Tables below. Table: Valve Seat Leakage Classification Leakage Maximum Allowable Leakage Class Designation I II III IV V
--0.5% of rated capacity 0.1% of rated capacity 0.01% of rated capacity 5 x 10-12 m3 /s of water per mm of seat diameter per bar differential (0.0005 ml/min per inch of seat diameter per psi differential) VI Not to exceed amounts shown in Table 10-6 (based on seat diameter) of ANSI/FCI 70-2 Source: ANSI/FCI 70-2 Table: Class VI Valve Seat Allowable Leakage Nominal Port Diameter mm (in) 25 (1) 38 (1½)
Allowable Leakage Rate (ml per minute) 0.15 0.30
51 (2) 64 (2½) 76 (3) 102 (4) 152 (6) 203 (8) Source: ANSI/FCI 70-2
0.45 0.60 0.90 1.70 4.00 6.75
Packing: Most valves use packing boxes with the packing retained and adjusted by flange and stud bolts. Several packing materials are available for use, depending upon the application. End Connections: The common end connections for installing valves in pipe include screwed pipe threads, bolted flanges with gasket, welded connections, and flangeless (or wafer) valve bodies. Screwed end connections are typically used with small-bore valves. Threads are normally specified as tapered female National Pipe Thread (NPT). This end connection is limited to valves below 50 mm (2 in) and smaller but is not recommended for elevated temperature service. This connection is also used in low maintenance or non-critical applications. Flanged end valves are easily removed from piping and, with proper flange specifications, are suitable for use through the range of most valve working pressures. Flanges are used on all valve sizes 50 mm (2 in) and larger. The most common types of flanged end connections are flat faced, raised faced, and the ring joint. Flat-faced flanges are typically used in low pressure, cast iron, or brass valves and have the advantage of minimizing flange stresses. Raised faced flanges can be used for high pressure and temperature applications and are normally as per standard ANSI Class 150# and above on all steel and alloy steel bodies. The ring-type joint flange is typically used at extremely high pressures of up to 103 MPa (15,000 psig) and also at high temperatures. This type of flange is furnished only on steel and alloy valve bodies when specified. Welding ends on valves have the advantage of being leak tight at all pressures and temperatures; however, welding end valves are very difficult to remove for maintenance and/or repairs and hence, the uses are limited to very high pressure and temperature. Welding ends are manufactured in butt weld style. Flangeless valve bodies are also called wafer-style valve bodies. This body style is common to rotary shaft control valves such as butterfly valves and ball valves. Flangeless bodies are clamped between two pipeline flanges by long through-bolts. One of the advantages of a wafer-style body is that it has a very short face-to-face body length. 00C Table: Type and application of Valve Packing Type PTFE
Application Resistant to most chemicals. Requires extremely smooth stem finish to seal properly. Will leak if stem or packing is damaged. Laminated/Filament Impervious to most liquids and Graphite radiation. Can be used at high temperatures, up to 6500C (1,2000F). Produces high stem friction. Semi-Metallic Used for high pressures and 0 0 temperatures, up to 480 C (900 F). Fibreglass Good for general use. Used with process temperatures up to 2880C (5500F).
Ferritic steel stems require additive to inhibit pitting. Kevlar and Good for general use. Graphite Used with process temperatures up to 2880C (5500F). Corrosion inhibitor is included to avoid stem corrosion. Source: Compiled by SAIC, 1998 Valve Supports: Specific pipe material design recommendations are followed when designing supports for valves. In general, one hanger or other support should be specified for each side of a valve, that is, along the two pipe sections immediately adjacent to the valve. The weight of the valve is included in the calculation of the maximum span of supports. Valve Schedule: This Valve Schedule can provide useful data. For design purposes, contract drawings include a valve schedule. Following Table presents a valve schedule that is included in the drawings for process piping design. This valve operator schedule is used when additional information, beyond that shown on a valve schedule, is required. TABLE: VALVE SCHEDULE Valve Description Size Flange Screw Type Range Rating Ends Ball Ball Valve, 40 mm Taper -Valve Full Port & ANSI Positive Smaller B2.1 Shut-off
Ball Valve, 40 mm Full Port & Positive Greater Shut-off
Design Body Rating Materials 1.39 316 SS MPa
ANSI B16.5 Class 150#
--
689 kPa
316 SS
Ball Valve, 40 mm ANSI Full Port & B16.5 Positive Smaller Class
--
1.03 MPa
316 SS
Trim Materials SS 316 Ball & Stem Glass Filled TFE Seats, TFE Seals SS 316 Ball & Stem Glass Filled TFE Seats, TFE Seals SS 316 Ball & Stem
Shut-off
300#
Glass Filled TFE Seats, TFE Seals 689 CS 13% Cr kPa ASTM A Steel and 216 Seats & above GR WCB SS Stem
Gate Solid 50 mm Valve Wedge Gate & Valve Larger O.S. & Y., Rising Stem
ANSI B16.5 Class 150# and above
--
Double 50 mm Disc Gate & Valve Larger O.S. & Y., Rising Stem
ANSI B16.5 Class 150#
--
689 kPa
CS UT Trim ASTM A 316 SS 216 Stem GR WCB
50 mm ANSI & B16.5 Larger Class 150# and above 50 mm -& Smaller 50 mm -& Smaller
--
689 kPa and above
CS ASTM A 216 GR WCB
13% Cr Steel Seats & Disc
Taper ANSI B2.1 Socket Weld
1.39 MPa
Bronze
Bronze
17.2 MPa
CS ASTM 105
13% Cr A Steel Seats & 302 SS Spring
PFA Coated Steel
Check Swing Valve Check Valve
Swing Check Valve Y-Pattern Check Valve
Lined Wafer Check Valve
250 mm
Fit ANSI B16.5 Class 150#
--
689 kPa
PFA Coated CS
Wafer Style 100 Check mm Valve to
Fit ANSI B16.5
--
689 kPa
410 SS 302 SS ASTM A 276
PCV
250 mm 100 mm
Globe Valve, Bolted Bonnet, O.S. & Y., Rising Stem Butterfly 100 Valve mm
Butterfly Valve
300 mm
Class 150# Fit ANSI B16.5 Class 150# Fit ANSI B16.5 Class 150# Fit ANSI B16.5 Class 150#
--
689 kPa
CS 302 SS ASTM A 216 GR WCB
--
689 kPa
PFA Lined D.I.
PFA Lined D.I. & SS Stem
--
689 kPa
PFTE Lined CS
PTFE Lined CS & SS Stem
Source: SAIC, 1998.
VALVE S PECIFICATIONS GATE VALVE SPECIFICATION - I MAX TEMP 0C
Material
Body Bonnet (Forge/ Cast) Cast) A105 A216 GR WCB
PIPING CLASS
Seat Rising Wedge Disc Renewable / (Forge/ Stem Rising (Solid/ Flex) NonRenewable
A105 A216 GR WCB
13%CR Steel
13% CR Steel
13% CR Steel 400ºC
A1A, A2A, A3A, A5A, A7A, A10A B1A, B2A, B5A, B7A, B10A, J3A
A105 A216 GR WCB A105 A216 GR WCB A105 A216 GR WCB A182 F304L A351 GR CF8
A105 A216 GR WCB A105 A216 GR WCB
SS 304/ SS 304L
SS 304/ SS 304L
SS 304/ SS 304L
Stellite
Stellite
13%CR Steel Stellite
400ºC
A12A, A13A
400ºC
D1A, D2A
400ºC
F1A, F2A
540ºC
A10K
Stellite
A105 A216 GR WCB
13%CR Steel
A182F 304L A351 GRCF8
SS 304L
SS 304L
SS 304L
SS 304
A182F304 SS 304
A182F304 SS 540ºC 304
Stellite
Stellite
A182 F304 A182F A351 304 A351 GR GRCF8 CF8 A182 F304 A182F A351 304 A351 GR GRCF8 CF8 A105 A105 A216 A216 GR GR WCB WCB A105 A105 A216 A216 GR GR WCB WCB A350 A350 GRLF2 A352 GRLF2 A352 GRLCB GRLCB
SS 304 13%CR Steel
13%CR Steel
SS 304
SS 304
SS 304
Stellite
Stellite
SS 304
A1K, A13K, B1K, B13K
540ºC
F1K
200ºC
A20A, B20A
200ºC
A9A, A19A, B9A, B19A
-45ºC
A4A, A40A, B4A, B40A
13%CR Steel
A350 GRLF3 A352 GRLC3 A182 F304 A351 GRCF8 A182 F11 A217 GR WC6 A182 F11 A217 GR WCB
A350 GRLF3 A352 GRLC3 A182 F304 A351 GRCF8
Stellite SS 304 Stellite
Stellite
13%CR Steel
Stellite
-80ºC
A1H, A10H, B1H, B10H
-196ºC
A2K, A20K, B2K, B20K
550ºC
A1D, A2D, B1D, D2D
550ºC
F1D, F2D
Stellite
SS 304
13%CR A182 F11 A217 Steel GR WC6
A182 F11 A217 GR WCB
Stellite
Stellite
Stellite
A182 Stellite Stellite F22 A182F22 A217 13%CR G2E 560ºC A217 Steel GR WC9 GR WC9 A182 A182F316H F316H A351 SS SS SS 685ºC A13K, B13K A351 GR 316H 316H 316H GR CF8M CF8M 1) Rating; Ends; Manufacturing Standards; Dimension Standards; End Thickness & others, if any, should be done as per piping class of piping material specifications. 2) Valve body and Valve seat testing should be done as per "API 598" OR, IBR at the following test pressure. 3) Valve should be provided with Gear as per Table. 4) Valve for IBR SERVICE, the carbon content in valve body should not exceed 0.25% and should be certified by IBR authority in "Form IIIC" certificate and should be painted Red for identification 5) All Valves should be "0.S & Y" in construction. 6) All Valves in cold service should be provided with extended Bonnet as per BS 6364 and 100% body should be radiographic by X-Ray.
Hydro test Pressure
Seat (psig)
Pneumatic Test Pressure Rating (psig)
2175 310 805 1060 1590
80 80 80 80 80
Rating
Body (psig) 800# *3000 150# 425 300# 1100 400# 1450 600# 2175
900# 1500# 2500# 3000#
Hydro test Pressure Body (psig) 3250 5400 9000 4500
Seat (psig) 2375 3950 6570 4050
Pneumatic Test Pressure (psig) 80 ----------
GATE VALVE SPECIFICATION - II MAX TEMP 0C
Material
Body Bonnet (Forge/ Cast) Cast)
A105 A216 GR WCB
A105 A216 GR WCB A105 A216 GR
(Forge/ Stem Rising
PIPING CLASS
Seat Rising Wedge Disc Renewable / (Solid/ Flex) NonRenewable
A105 A216 GR WCB
13%CR Steel
13% CR Steel
13% CR Steel 400ºC
A1A, A2A, A3A, A5A, A7A, A10A B1A, B2A, B5A, B7A, B10A, J3A
A105 A216 GR WCB
SS 304/ SS 304L
SS 304/ SS 304L
SS 304/ SS 304L
400ºC
A12A, A13A
Stellite
Stellite 400ºC
D1A, D2A
A105 A216 GR WCB
13%CR Steel
WCB A105 A216 GR WCB A182 F304L A351 GR CF8 A182 F304 A351 GR CF8 A182 F304 A351 GR CF8
Stellite
A105 A216 GR WCB
13%CR Steel
A182F 304L A351 GRCF8
SS 304L
A182F 304 A351 GRCF8
A182F 304 A351 GRCF8
A105 A105 A216 A216 GR GR WCB WCB A105 A105 A216 A216 GR GR WCB WCB A350 A350 GRLF2 GRLF2 A352 A352 GRLCB GRLCB A350 A350 GRLF3 GRLF3 A352 A352 GRLC3 GRLC3 A182 A182 F304 F304 A351 A351 GRCF8
SS 304
Stellite 400ºC
F1A, F2A
540ºC
A10K
A182F304 SS 304
A182F304 SS 540ºC 304
A1K, A13K, B1K, B13K
Stellite
Stellite
SS 304L
SS 304L
SS 304
13%CR Steel
SS 304
540ºC
13%CR Steel
13%CR Steel 200ºC
SS 304
SS 304
Stellite
Stellite
SS 304 Stellite
SS 304
-80ºC Stellite
SS 304
200ºC
-45ºC Stellite
F1K
Stellite -196ºC
A20A, B20A A9A, A19A, B9A, B19A A4A, A40A, B4A, B40A A1H, A10H, B1H, B10H A2K, A20K, B2K,
B20K
GRCF8 A182 F11 A217 GR WC6 A182 F11 A217 GR WCB A182 F22 A217 GR WC9 A182 F316H A351 GR CF8M
13%CR A182 F11 A217 Steel GR WC6
Stellite
13%CR Steel
Stellite
A182 F11 A217 GR WCB
Stellite A182F22 A217 GR WC9
13%CR Steel
A182F316H A351 GR CF8M
SS 316H
SS 316H
Stellite 550ºC
A1D, A2D, B1D, D2D
550ºC
F1D, F2D
560ºC
G2E
685ºC
A13K, B13K
Stellite
Stellite
SS 316H
1) Rating; Ends; Manufacturing Standards; Dimension Standards; End Thickness & others, if any, should be done as per piping class of piping material specifications. 2) Valve body and Valve seat testing should be done as per "API 598" OR, IBR at the following test pressure 3) Valve should be provided with Gear as per Table in the book 4) Valve for IBR SERVICE, the carbon content in valve body should not exceed 0.25% and should be certified by IBR authority in "Form IIIC" certificate and should be painted Red for identification 5) All Valves should be "0.S & Y" in construction. 6) All Valves in cold service should be provided with extended Bonnet as per BS 6364 and 100% body should be radiographic by X-Ray. Hydro test Pressure Rating
Pneumatic Test Pressure Rating (psig)
Hydro test Pressure
Pneumatic Test Pressure
80
900#
Body (psig) 3250
150# 425 310 300# 1100 805
80 80
1500# 2500#
5400 9000
3950 6570
400# 1450 1060 600# 2175 1590
80 80
3000#
4500
4050
800# *
Body Seat (psig) (psig) 3000 2175
GLOBE VALVE SPECIFICATION - I MATERIAL Body Bonnet (Forge/ (Forge/ Cast) Cast) A105 A216 GR WCB
A105 A216 GR WCB
Seat Ring MAX Disc Stem Renewable TEMP (Loose/ Rising / Non- 0C Plug Type Renewable 13%CR 13%CR 13%CR Steel Steel Steel
A105 SS A105 A216 A216GR 304/ SS GR WCB 304L WCB A105 A105 A216 13%CR A216 GR Steel GR WCB WCB A105 A105 A216 13%CR A216 GR GR Steel WCB WCB A182 F304L A351
A182 F304L A351
SS 304/ SS 304L
SS 304/ SS 304L
Stellite
Stellite
Stellite
PIPING CLASS
400ºC
A1A, A2A, A3A, A5A, A7A, A10A B1A, B2A, B5A, B7A, B10A, J3A
400ºC
A12A, A13A
400ºC
D1A, D2A
400ºC
F1A, F2A
540ºC
A10K
Stellite
SS 304L SS 304L SS 304L
Seat (psig) (psig) 2375 80
GRCF8 GRCF8 A182 F304 A351 GRCF8 A182 F304 A351 GRCF8
A182 F304 A351 GRCF8 A182 F304 A351 GRCF8
A105 A216 GR WCB A105 A216 GR WCB A350 GRLF2 A352 GrLCB A350 GRLF3 A352 GrLC3 A182 GR F304 A351 GRCF8 A182 GRF11 A217 GrWC6 A182 GRF11 A217 GrWCB A182 GRF22
A105 A216 GR WCB A105 A216 GR WCB A350 GRLF2 A352 GrLCB A350 GRLF3 A352 GrLC3 A182 GR F304 A351 GRCF8 A182 GRF11 A217 GrWC6 A182 GRF11 A217 GrWCB A182 GRF22
SS 304
A182F304 A182F304 540ºC SS 304 SS 304 Stellite
Stellite
SS 304 13%CR 13%CR Steel Steel
13%CR Steel
SS 304
SS 304
SS 304
Stellite
Stellite
SS 304 Stellite
F1K
200ºC
A20A, B20A
200ºC
A9A, A19A, B9A, B19A
-45ºC
A4A, A40A, B4A, B40A
-80ºC
A1H, A10H, B1H, B10H
-196ºC
A2K, A20K, B2K, B20K
550ºC
A1D, A2D, B1D, D2D
550ºC
F1D, F2D
Stellite
SS 304 13%CR Stellite Steel
Stellite
13%CR Stellite Steel
Stellite
Stellite
Stellite
13%CR
540ºC
Stellite
SS 304 Stellite
A1K, A13K, B1K, B13K
A217 A217 GrWC9 GrWC9 A182 GR F316H A351 Gr CF8M
A182 GR F316H A351 Gr CF8M
Steel
SS 316H
SS 316H
SS 316H
560ºC
G2E
685ºC
A13K, B13K
1) Rating; Ends; Manufacturing Standards; Dimension Standards; End Thickness & others, if any, should be done as per piping class of piping material specifications 2) Globe Valve body and Valve Seat testing should be done as per "API 598" OR, IBR at the following test pressure. 3) Valve should be provided with Gear as per table in book. Valve for IBR SERVICE, the carbon content in valve body should not exceed 0.25% and should be certified by IBR authority in "Form IIIC" certificate and should be painted Red for identification 4) All Valves should be "0.S & Y" in construction. 5) All Valves in cold service should be provided with extended Bonnet as per BS 6364 and 100% body shall be radiographic by X-Ray.
Hydro Pressure Rating Body (psig) 800# * 3000 150# 425 300# 1100
Seat (psig) 2175 310 805
400#
1450 1060
600#
2175 1590
test
Hydro Pressure
Pneumatic Test Pressure Rating (psig) Body (psig) 80 900# 3250 80 1500# 5400 80 2500# 9000 3000# 80 4500 ** 80
GLOBE VALVE SPECIFICATION - II
Seat (psig) 2375 3950 6570 4050
test
Pneumatic Test Pressure (psig) 80
MATERIAL Seat Ring MAX Body Bonnet Disc Stem Renewable TEMP 0C (Forge/ (Forge/ (Loose/ Rising / NonCast) Cast) Plug Type Renewable 13%CR 13%CR 13%CR Steel A105 A105 Steel Steel A216 A216 400ºC GR GR WCB WCB A105 A105 A216 A216GR GR WCB WCB A105 A105 A216 A216 GR GR WCB WCB A105 A105 A216 A216 GR GR WCB WCB A182 A182 F304L F304L A351 A351 GRCF8 GRCF8 A182 F304 A351 GRCF8 A182 F304 A351 GRCF8 A105 A216 GR
A182 F304 A351 GRCF8 A182 F304 A351 GRCF8 A105 A216 GR
SS SS 304/ SS 304/ SS 304L 304L Stellite
SS 304/ SS 304L
400ºC
A12A, A13A
400ºC
D1A, D2A
400ºC
F1A, F2A
540ºC
A10K
Stellite
13%CR Steel
SS 304L
SS 304L
SS 304
A182F304 A182F304 540ºC SS 304 SS 304
SS 304L
Stellite
A1K, A13K, B1K, B13K
Stellite
SS 304 13%CR 13%CR Steel Steel
A1A, A2A, A3A, A5A, A7A, A10A B1A, B2A, B5A, B7A, B10A, J3A
Stellite
13%CR Steel Stellite
PIPING CLASS
13%CR Steel
540ºC
F1K
200ºC
A20A, B20A
WCB A105 A216 GR WCB A350 GRLF2 A352 GrLCB
WCB A105 A216 GR WCB A350 GRLF2 A352 GrLCB A350 A350 GRLF3 GRLF3 A352 A352 GrLC3 GrLC3 A182 GR F304 A351 GRCF8 A182 GRF11 A217 GrWC6
SS 304
SS 304
SS 304
Stellite
Stellite
SS 304 Stellite
A9A, A19A, B9A, B19A
-45ºC
A4A, A40A, B4A, B40A
-80ºC
A1H, A10H, B1H, B10H
-196ºC
A2K, A20K, B2K, B20K
550ºC
A1D, A2D, B1D, D2D
550ºC
F1D, F2D
Stellite
SS 304
A182 Stellite GR SS F304 304 A351 GRCF8 A182 13%CR Stellite GRF11 Steel A217 GrWC6 A182 A182 13%CR Stellite GRF11 GRF11 Steel A217 A217 GrWCB GrWCB
200ºC
Stellite
Stellite
Stellite
A182 A182 Stellite Stellite GRF22 GRF22 13%CR 560ºC G2E A217 A217 Steel GrWC9 GrWC9 A182 A182 GR GR SS SS F316H F316H SS 685ºC A13K, B13K A351 A351 316H 316H 316H Gr Gr CF8M CF8M 1) Rating; Ends; Manufacturing Standards; Dimension Standards; End Thickness & others, if any, should be done as per piping class of piping
material specifications 2) Globe Valve body and Valve Seat testing should be done as per "API 598" OR, IBR at the following test pressure. 3) Valve should be provided with Gear as per table in book. Valve for IBR SERVICE, the carbon content in valve body should not exceed 0.25% and should be certified by IBR authority in "Form IIIC" certificate and should be painted Red for identification 4) All Valves should be "0.S & Y" in construction. 5) All Valves in cold service should be provided with extended Bonnet as per BS 6364 and 100% body shall be radiographic by X-Ray.
Rating
Hydro Hydro test Pneumatic Pressure Pressure Test Pressure Rating (psig)
800# * 150# 300#
Body (psig) 3000 425 1100
Seat (psig) 2175 80 310 80 805 80
400#
1450 1060 80
600#
2175 1590 80
Body (psig) 900# 3250 1500# 5400 2500# 9000 3000# 4500 **
test Pneumatic Test Pressure (psig)
Seat (psig) 2375 3950 6570 4050
80
BALL VALVE SPECIFICATION - I MATERIAL
MAX TEMP 0C
S. NO Body Stem Gland (Forge/ Anti- Bolted/ Cast) Blowout Welded A105 A216GR WCB
13%CR 13%CR Steel Steel
BALL & Full Bore) 13%CR SS304
PIPING CLASS
(Solid BODY SEAT
Steel
Reinforced PTFE with / secondary 200ºC metal to metal/ PTFE Reinforced
A1A, A5A, A3A, A7A,
A350 SS GR F2 304 A352 GR LCB A105 SS A216GR 304 WCB A182 GR F304 A351 GR CF8 A182 GR F304 A351 GR CF8
SS304/ SS316
SS 304
SS304/ SS316
SS 304
SS 304
SS304/ SS316
SS 304
SS 304
SS304/ SS316
A350 GR LF3 SS A352 304 GR LC3 A105 A216GR WGB
SS 304
SS 304
13%CR 13%CR Steel Steel
13%CR 13%CR Steel Steel
SS304/ SS316
13%CR Steel
PTFE with -45ºC secondary metal to metal/ PTFE Reinforced PTFE with secondary 200ºC metal to metal/ PTFE Reinforced PTFE with secondary 200ºC metal to metal/ PTFE Reinforced PTFE with secondary -196ºC metal to metal/ PTFE Reinforced PTFE with secondary -80ºC metal to metal/ PTFE Reinforced PTFE with secondary 200ºC metal to metal/ PTFE
A4, A40A, B4A, B40A
A9A, A19A, B9A, B19A
A12A, A13A
A2K, A20K, B2K, B20K
A1H, A10H, B1H, B10H
A1A, A3A, A7A, B1A, B3A, B7A
Reinforced A20A, A105 PTFE with SS304/ SS316 B20A A216GR secondary 200ºC metal to metal/ B4A WGB PTFE A182 Reinforced GR PTFE with SS SS SS304/ SS316 F304 secondary -196ºC D2K (Cryo) 304 304 A351 metal to metal/ GR CF8 PTFE 1) Rating; Ends; Manufacturing Standards; Dimension Standards; End Thickness & others, if any,
should be done as per piping class of piping material specifications 2) Ball valve should be fire safe tested as per API 607/BS 6755 (Part-II) or API RP 6F. 3) Body Seat of Trunion mounted Ball Valves should be spring loaded and the location of spring should not be in flow direction. 4) Ball Valve should be Bi-directional. 5) Ball Valve should be provided with "Stop" at 90 degree Location to insure positive open/close alignment with ports and position indicator. 6) Ball Valves should be provided with pressure relieving device for body and bonnet cavity. 7) All Valves in cold service should be provided with extended Bonnet as per BS 6364.
Rating
Hydrotest Pressure Seat Body (psi)
800# * 150# 300#
Hydrotest Pressure
Pneumatic Test Rating Pressure
3000 2175 80 425 310 80 1100 805 80
400# 600# --
Body
Seat
Pneumatic Test Pressure
1450 2175 --
1060 1590 --
80 80 --
BALL VALVE SPECIFICATION - II MATERIAL
MAX PIPING TEMP CLASS 0C
S. NO Body (Forge/ Cast)
1
A105 A216GR WCB
Stem Anti- Gland Blowout Bolted/ Welded 13%CR Steel
A350 GR F2 SS
13%CR Steel
SS
BALL & Full Bore) 13%CR SS304
(Solid BODY SEAT
Steel
Reinforced PTFE with / secondary 200ºC metal to metal/ PTFE Reinforced PTFE with
A1A, A5A, A3A, A7A, A4, A40A,
2 A352 GR LCB 304
304
SS304/ SS316
A105 A216GR SS 304 WCB
SS 304
SS304/ SS316
A182 GR SS A351 4 F304 304 GR CF8
SS 304
SS304/ SS316
3
A182 GR SS A351 5 F304 304 GR CF8
6
7
SS 304
A350 GR LF3 SS A352 GR LC3 304
SS 304
13%CR A105 A216GR Steel WGB
13%CR Steel
13%CR Steel
13%CR Steel
SS304/ SS316
SS304/ SS316
13%CR Steel
-45ºC secondary metal to metal/ PTFE Reinforced PTFE with secondary 200ºC metal to metal/ PTFE Reinforced PTFE with secondary 200ºC metal to metal/ PTFE Reinforced PTFE with secondary -196ºC metal to metal/ PTFE Reinforced PTFE with secondary -80ºC metal to metal/ PTFE
B4A, B40A
Reinforced PTFE with secondary 200ºC metal to metal/ PTFE
A1A, A3A, A7A, B1A, B3A, B7A
A9A, A19A, B9A, B19A
A12A, A13A
A2K, A20K, B2K, B20K A1H, A10H, B1H, B10H
Reinforced A20A, PTFE with A105 A216GR SS304/ SS316 secondary 200ºC B20A 8 WGB metal to metal/ B4A PTFE Reinforced A182 GR PTFE with SS SS D2K SS304/ SS316 A351 secondary -196ºC 9 F304 304 304 (Cryo) GR CF8 metal to metal/ PTFE 1) Rating; Ends; Manufacturing Standards; Dimension Standards; End Thickness & others, if any,
should be done as per piping class of piping material specifications 2) Ball valve should be fire safe tested as per API 607/BS 6755 (Part-II) or API RP 6F. 3) Body Seat of Trunion mounted Ball Valves should be spring loaded and the location of spring should not be in flow direction. 4) Ball Valve should be Bi-directional. 5) Ball Valve should be provided with "Stop" at 90 degree Location to insure positive open/close alignment with ports and position indicator. 6) Ball Valves should be provided with pressure relieving device for body and bonnet cavity. 7) All Valves in cold service should be provided with extended Bonnet as per BS 6364. Hydrotest Rating Pressure
800# * 150# 300#
Pneumatic Test Rating Pressure
Body
Seat (psi)
3000 425 1100
2175 310 805
Hydrotest Pressure Body
80 80 80
400# 600# --
1450 2175 --
Pneumatic Test Pressure Seat 1060 80 1590 80 ---
CHECK VALVE SPECIFICATION - I MATERIAL
Body (Forge/ Cast)
Cover Piston/Ball/ Disc Welded/ Bolted 13%CR Steel
A105 A216GR WCB
A105 A216 GR WCB
MAX TEMP 0C Body Seat Ring Integral/ Renewable 13%CR Steel
400ºC
PIPING CLASS
A1A, A2A, A3A, A5A, A7A, A10A B1A, B2A,
B5A, B7A, B10A, J3A A105 A216GR WCB
A105 A216 GRWCB
A105 A216 GR WCB A105 A216 A105 A216GR GR WCB WCB A182F304L A182F304L A351GR A351 CF8 GRCF8 A182F304 A182 A351GR F304 A351 CF8 GRCF8 A182F304 A182 A351GR F304 A351 CF8 GRCF8 A105 A216 A105 A216GR GR WCB WCB A105 A216GR WCB
A105 A216GR WCB
A105 A216 GR WCB
A350GR A350 LF2 A352Gr GRLF2 A352 LCB GrLCB
A350 A350GR LF3 A352Gr GRLF3 A352 LC3 GrLC3 A182F304 A351GR CF8
A182 F304 A351 GRCF8
SS304/ SS 304L
SS304/ SS304L 400ºC
A12A, A13A
Stellite 13%CR Steel
400ºC
D1A, D2A
400ºC
F1A, F2A
Stellite 13%CR Steel SS 304L
A182 540ºC F304L SS304L
A10K
SS304
A182 F304 SS304
540ºC
A1K, A13K, B1K, B13K
540ºC
F1K
200ºC
A20A, B20A
200ºC
A9A, A19A, B9A, B19A
-45ºC
A4A, A40A, B4A, B40A, D4A, D40A
-80ºC
A1H, A10H, B1H, B10H D1H, D10H
-196ºC
A2K, A20K, B2K, B20K, D2K, D20K
Stellite SS304 13%CR Steel
SS304
13%CR Steel
SS304 Stellite
SS304
Stellite SS304 Stellite SS304 13%CR Steel
Stellite
A182F11 A217Gr WC6
A182 F11 A217 GrWC6
A182F11 A217Gr WC6
A182 F11 A217 GrWC6
A182F22 A217Gr WC9
A182 F22 A217 GrWC9
550ºC
13%CR Steel
A1D, A2D, B1D, D2D F1D, F2D
Stellite 550ºC
F1D, F2D
560ºC
G2E
Stellite 13%CR Steel
A182 A182F316H F316H A351 SS SS A13K, B13K 16 A351Gr 685ºC Gr 316H 316H CF8M CF8M 1) Rating; Ends; Manufacturing Standards; Dimension Standards; End Thickness & others, if any, should be done as per piping class of piping material specifications. 2) Valve body and Valve seat testing should be done as per BS675 OR, IBR at the following test pressure. 3) All Valve above 6" NB and above should have independent spring for each plate. 3) Valve for IBR SERVICE, the carbon content in valve body should not exceed 0.25% and should be certified by IBR authority in "Form IIIC" certificate and should be painted Red for identification 4) Vendor should specify that Bearing/Bushing material is suitable for the service. 5) All castings should be solution heat treated for piping class A1K, A3Y, A13A, A12A, A2K, A10K, B1K, and B2K & B20K. 6) All Valves of size 0.5" TO 1.5"should have Piston Type Check Valve or Spring Loaded Ball Type Lift check valve as per BS 5352. 7) All Valves of size 2" TO 24"should have Disc Type Swing Check Valve as per BS1868 and Spring Loaded Dual Plate Type Swing check valve as per API 594
Rating
800# * 150# 300# 400# 600#
Hydrotest Pressure Body Seat (psig) (psig)
Pneumatic Pressure (psig)
Rating
Hydrotest Pressure Body (psig)
Test
Seat (psig)
3000 2175
80 psig
900#
3250
2375
425 1100 1450 2175
80 psig 80 psig 80 psi 80 psi
1500# 2500# 3000# **
5400 9000 4500
3950 6570 4050
310 805 1060 1590
CHECK VALVE SPECIFICATION - II MATERIAL
Body (Forge/ Cast)
A105 A216GR WCB
A105 A216GR WCB A105
MAX PIPING Body Seat TEMP CLASS Cover 0C Piston/Ball/ Ring Welded/ Disc Integral/ Bolted Renewable 13%CR 13%CR A1A, Steel Steel A2A, A3A, A5A, A7A, A105 A216 A10A GR 400ºC B1A, WCB B2A, B5A, B7A, B10A, J3A A105 A216 SS304/ SS SS304/ SS304L GRWCB 304L A105 A216
13%CR
Stellite
400ºC
A12A, A13A D1A,
Pneumatic Test Pressure (psig) 80 psi
A216GR WCB A105 A216GR WCB A182F304L A351GR CF8
Steel GR WCB A105 A216 13%CR GR Steel WCB A182F304L SS A351 304L GRCF8
A182F304 A351GR CF8
400ºC D2A Stellite 400ºC
F1A, F2A
A182 F304L SS304L
540ºC A10K
A182 F304 A351 SS304 GRCF8
A182 F304 SS304
A1K, A13K, 540ºC B1K, B13K
A182F304 A351GR CF8 A105 A216GR WCB
A182 F304 A351 SS304 GRCF8 A105 A216 13%CR Steel GR WCB
Stellite
A105 A216GR WCB
A105 A216 SS304 GR WCB
540ºC F1K 13%CR Steel
SS304 Stellite
A350 A350GR GRLF2 LF2 A352Gr A352 LCB GrLCB
SS304
Stellite A350 A350GR LF3 A352Gr GRLF3 A352 LC3 GrLC3
SS304
Stellite A182F304 A351GR CF8
A182 F304 A351 SS304 GRCF8
200ºC
A20A, B20A
A9A, A19A, 200ºC B9A, B19A A4A, A40A, B4A, -45ºC B40A, D4A, D40A A1H, A10H, B1H, -80ºC B10H D1H, D10H A2K, A20K, B2K, -196ºC B20K, D2K, D20K
Stellite
A182F11 A217Gr WC6
A182 F11 A217 GrWC6
13%CR Steel
A182F11 A217Gr WC6
13%CR A182 Steel F11 A217 GrWC6
Stellite
A182F22 A217Gr WC9
A182 13%CR F22 A217 Steel GrWC9
Stellite
A1D, A2D, B1D, 550ºC D2D F1D, F2D 550ºC
F1D, F2D
560ºC G2E
A182 A182F316H F316H SS SS A13K, A351 685ºC 16 A351Gr B13K 316H 316H CF8M Gr CF8M 1) Rating; Ends; Manufacturing Standards; Dimension Standards; End Thickness & others, if any, should be done as per piping class of piping material specifications. 2) Valve body and Valve seat testing should be done as per BS675 OR, IBR at the following test pressure. 3) All Valve above 6" NB and above should have independent spring for each plate. 3) Valve for IBR SERVICE, the carbon content in valve body should not exceed 0.25% and should be certified by IBR authority in "Form IIIC" certificate and should be painted Red for identification 4) Vendor should specify that Bearing/Bushing material is suitable for the service. 5) All castings should be solution heat treated for piping class A1K, A3Y, A13A, A12A, A2K, A10K, B1K, and B2K & B20K. 6) All Valves of size 0.5" TO 1.5"should have Piston Type Check Valve or Spring Loaded Ball Type Lift check valve as per BS 5352. 7) All Valves of size 2" TO 24"should have Disc Type Swing Check Valve as per BS1868 and Spring Loaded Dual Plate Type Swing check valve as per API 594.
Hydro Test Pneumatic Hydro Test Pneumatic Test Test Pressure Pressure Rating Rating Pressure Body Seat Pressure Body Seat (psig) (psig) (psig) (psig) (psig) (psig) 800# 3000 2175 80 psig 900# 3250 2375 80 psi * 150# 425 310 80 psig 1500# 5400 3950 300# 1100 805 80 psig 2500# 9000 6570 3000# 400# 1450 1060 80 psi 4500 4050 ** 600# 2175 1590 80 psi Note: Source ANSI B16.5, API 602 and API Spec. 6A (metal valve part only). Following denoting is applicable for all the Valves Specification Tables: * Indicates API Pressure Class 800 in psi and applies to Valve only. ** Indicates API Pressure Class 3000 in psi and applies to Flange only. # Indicates ANSI Pressure Class in lb. @ Indicates API Pressure Class 3000 in psi and applies to Flange 16” and larger only. $ Indicates API Pressure Class 6000 in psi and applies to Flange 14” and smaller only. LI MI TATI ON ON VALVE SELECTI ON: Plug Valves and Ball Valves are not permitted for use above 2000C due to their soft seat. Accordingly, Plug and Ball Valves restricted for use in IBR lines and all other lines having temperature more than 2000C. Valves should be designed, manufactured, tested, inspected and marked with a tag or punching or casting or by all three methods as per design code and standards. Valves to be used for “CRYO” service should be supplied with Bonnet extension should be tested to the cryogenic test as per BS 6364 and should be witnessed by third party. Heavy valves should be provided with lifting lugs, or Eye bolts for lifting and installation purpose. All flanged valves should have cast flange (integral flange). Welded- On flanges are not allowed. All flanges should be Serrated Finished to 125 AARH (125 to 200 AARH) or 250 AARH (250 to 500 AARH) or 63 AARH (32 to 63 AARH). All check Valves 3” and above, should have a drain boss at the bottom. It should be provided with a tapped drain hole with a plug of size 0.5” to 0.75” as per ANSI B16.34. All valves, size 26” and above in Class 150#; 16” and above in Class 300#; 6” and above in Class 600#; 4” and above in Class 900# & 1500#; and 3” and above in Class 2500# should be provided with a globe valve by-pass line in the centre of flow as per specifications The sizes of the by-pass line should be as mentioned below:
0.5” Globe valve by-pass on main line size up to 4”. 0.75” Globe valve by-pass on main line size up to 8” 1” Globe valve by-pass on main line size above 8”. By-pass valve direction should be marked for identification of the flow. All by-pass attachments to the main valve should be fillet welded and 100% Dye-penetration or magnetic particle tested as per MSS SP-45 and ANSI B16.34. Depositing the material 1.6 mm minimum thick should do Stelliting or hardening of the seat. All austenitic stainless steel valves should be inter granular corrosion tested (IGC) to ASTM A262, practice “B” and corrosion rate should not be more than 48 mils/ years. All ball valves should be tested for fire safe test as per API-607/API-6 FA or BS-6755, part-II, latest edition and the test should be witnessed by third party. All valves should be provided with Antistatic devices. All butt-welded or socket-welded ball valves should have 100 mm long pipe nipple welded to each end of the valve. Nipples should be welded prior to the assembly of the Teflon seats/seals so that it should not get burnt during welding. Face to face dimension of the ball valves, 12” and above in Class 150# are different than others, and are as per API-6D, long pattern. All valves should be provided with hand wheel, or hand-lever or wrench except heavy valves. All heavy valves should be provided with totally enclosed gearbox, grease casing, grease nipple and position indicators for Open/Close position on top of the stem with a limit stop. The detail of the gearbox is given below: Hand wheel diameter of the valve should not be more than 750 mm or the lever length more than 500 mm. The effort to operate the valve should not increase more than 35 kg at hand wheel periphery for any valve type or size. Whenever the effort exceeds 35 kg at hand wheel periphery, the valve should be provided with a gear operation as per above details. All valves should have the material test certificates; radiography and other NDT test certificates. The following test should be carried for all valves: 1% strip check to verify the compliance with specification. 10% for forged valves and 100% for cast valves, the hydrostatic test of body should be carried out. 10% of seats for all valves should be hydrostatic tested. The body of the cast valves under critical, lethal and toxic service conditions should be radio graphed minimum as per following requirements as per ANSI B16.34; otherwise it should be specified in the design documents. For non-corrosive services: For non-corrosive services, carbon steel meeting the requirements of API 600, API 6A, API 6D OR ANSI B16.5-1968 is satisfactory for valve bodies because of its strength, ductility and resistance to damage by fire. Cast or ductile iron valve bodies should not be used for hydrocarbon or glycol services because of their low impact properties. Non – ferrous valves are not suitable for process hydrocarbon service because they may fail in a fire; they may be suitable for instrument and control system service. Cast iron, ductile iron, and bronze body valves may be used for water services. One-half inch and smaller needle valves for process hydrocarbon service should be austenitic stainless steel, such as AISI 304 or AISI 316, for corrosion resistance and ease of operation. Resilient sealing materials used in valves include Buna N, Neoprene, Delrina, Vinton, Teflon, Nylon and Tetrafluoroethylene (TFE). Resilient sealing materials should be carefully selected to be
compatible with the process fluids selected to be compatible with the process fluids and temperatures. For low-pressure (200 psig or lower) salt-water service, butterfly valves with ductile iron body, aluminium-bronze disc, and AISI 316 stainless steel steam with Buna N seals are satisfactory. Gate valves in this service should be iron body bronze trim (IBBM). For highpressure (above 200 psig) salt-water applications, steel gate valves with aluminium-bronze trim give good service. Corrosive Service: Generally, carbon steel valve bodies with corrosion resistant internal trim are used for corrosive service. AISI 410 type stainless steel is generally used for internal trim. Austenitic stainless steels, such as AISI 316, may also be used for internal trim. Chloride Stress Cracking Service: Consideration should be given to chloride stress cracking when selecting trim materials. Sulphide Stress Cracking Service: Valve bodies and internal trim should be in accordance with NACE, MR –01-75. Table: Radiographic Inspection Requirements of Valves Material All All All
Rating 150#
Radiography 100% on valves 26” NIL on valves 24” 300# 100% on valves 18” NIL on valves 16” 400# and above 100% on all sizes valves
Table: Detail of gearbox to be provided on Valves Valve Piping Class Type Gate or 150#, 300#, 400# Diaphragm 600# 900# 1500#, 2500# Globe 900# 100#, 2500# Ball or 150#, 300# Plug 400#, 600# 900#, 1500# Butterfly 150#, 300#
Size of Valve Type of Gear >= 14” Bevel Gear >= 12” >= 6” >= 3” >= 6” Bevel Gear >= 3” >= 6” Helical >= 4” Gear >= 3” >= 6” Helical gear
4.4.2 Criteria
“Stress – Strain” Design
The previous design methods have concentrated on the evaluation of the pressure and temperature rating as design bases. In this method, once the system operating conditions have been established, the minimum wall thickness is determined based on the pressure integrity requirements. The design process for consideration of pressure integrity uses allowable stresses; thickness allowances based on system requirements and manufacturing wall thickness tolerances to determine minimum wall thickness. Allowable stress values for metallic pipe materials are generally contained in applicable design codes. The codes must be utilized to determine the allowable stress based on the requirements of the application and the material to be specified. For piping materials that are not specifically listed in an applicable code, the allowable stress determination is based on applicable code references and good engineering design. For example, ASME B31.3 Sec. 302.3.2 provides design references that address this type of allowable stress determination. These requirements address the use of cast iron, malleable iron, and other materials not specifically listed by the ASME B31.3. Stress-Strain Diagram: The Stress-Strain Diagram is achieved by plotting the available corresponding values of the stress and strain against each other, strain on the X-axis and stress on the Y-axis. The graph of stress ( ) along the y-axis and the strain ( ) along the x-axis is called the stressstrain diagram. The stress-strain diagram differs in form for various materials. The diagram shown below is for a medium-carbon structural steel. An arbitrary strain of 0.05 mm/mm is frequently taken as the dividing line between ductile or brittle materials. The following parameters are explained in detail before designing the piping system:
Fig: Stress-strain diagram of a medium-carbon structural steel Proportional Limit (Hooke's Law): The linear relation between elongation and the axial force is called Hooke's Law, which states that, within the proportional limit, the stress is directly proportional to strain or; The constant of proportionality is called the Modulus of Elasticity or Young's Modulus and is equal to the slope of the stress-strain diagram from O to P. Then,
.
Most metals have deformations that are proportional with the imposed loads over a range of loads. Stress is proportional to load and strain is proportional to deformation and expressed by the Hooke's law like, E = stress / strain = (Fn / A) / (dl / lo); Where, E = Young's modulus (N/m2) (lb/in2, psi). Modulus of Elasticity or Young's Modulus are commonly used for metals and metal alloys and expressed in terms 106 lbf/in2, N/m2 or Pa. Tensile modulus are often used for plastics and expressed in terms 105 lbf/in2 or GPa. Stress: Stress is the ratio of applied force F and cross section A, defined as "force per area". Strain: Strain is defined as "deformation of a solid due to stress" and can be expressed as ε = dl / lo = σ / E; Where, dl = change of length (m, in); lo = initial length (m, in); ε = unit less measure of engineering strain; E =Young’s Modulus (Modulus of Elasticity) (Pa, psi). The Ratings are the maximum allowable non-shock working gauge pressure at the temperature shown in the Rating Tables at certain interval of temperature. Intermediate Temperature–Pressure Rating can be obtained by a linear graph drawn between the two pressures and corresponding two temperatures. Working Stress, Allowable Stress, and Factor of Safety: Working stress is defined as the actual stress of a material under a given loading. The maximum safe stress that a material can carry is termed as the allowable stress. The allowable stress should be limited to values not exceeding the proportional limit. However, since proportional limit is difficult to determine accurately, the allowable tress is taken as either the yield point or ultimate strength divided by a factor of safety. The ratio of this strength (ultimate or yield strength) to allowable strength is called the factor of safety. Direct Stress or Normal Stress: Stress normal to the plane is usually denoted "normal stress" and can be expressed as, σ = Fn / A ------------ ---------------------------------------------------------
(1)
Where, σ = normal stress ((Pa) N/m2, psi); Fn = normal component force (N, lbf; A = area (m2, in2) Shear Stress: Stress parallel to the plane is usually denoted "shear stress" and can be expressed as τ = Fp / A ----------------------------------------------------------------------
(2)
Where, τ = shear stress ((Pa) N/m2, psi); Fp = parallel component force (N, lbf); A = area (m2, in2) Table: Allowable Stresses for ASTM A106 Gr B, Seamless Pipe (ANSI B31.3 – 1973) Metal Temperature (0 F) - 20 to 400 401 to 500 501 to 600 601 to 650
S (psi) 20,000 18,900 17,300 17,000
Basic allowable stress(s) in tension, compression and shearing for metals are as mentioned below: a) Steels and Stainless Steel (Pipe &Plate): For Austenitic stainless steel and nicked steels flange joints, the stress values are either 75% of the stress value in the table A-1 of ANSI B31.3.or two-thirds of the yield strength. The lower of one third of SMTS at room temperature and one third of tensile strength at temperature. The lower of two-third of SMYS at room temperature and two third of yield strength at temperature. For Austenitic stainless steels and Nickel alloy steels having similar stress strain behaviour, the lower of two third of SMYS at room temperature and 90% of yield strength at temperature. 100% of average stress for a creep rate of 0.01% per 1000 hours. 67% of the average stress of rupture at the end of 100,000 hours. 80% of the minimum stress of rupture at the end of 100,000 hours.. Structural grade material: The basic Allowable Stress (S) in tension for structural grade materials shall be taken as 0.92 times the basic allowable stress (S) of the metals other than bolting materials, cast iron and malleable iron as calculated above. Bolting materials: The basic Allowable Stress (S) value for bolting materials at temperature are determined as mentioned below and shall not exceed of the lowest of followings: The lower of one fourth of SMTS at room temperature and one fourth of tensile strength at temperature. Lower of two third of SMYS at room temperature and two third of yield strength at temperature. The lower of one fifth of SMTS and one-fourth of SMYS at temperature below creep range. Two-third of yield strength at temperature. 100% of the average stress for a creep rate of .01% per 1000 hour. 67% of the average stress for rupture at the end of 100,000 hour 80% of minimum stress for ruptures at the end of 100,000 hours. Cast iron: Basic allowable stress(s) value at temperature for cast iron shall be equal to the lowest of the following One-tenth of SMTS at room temperature. One tenth of tensile strength at temperature Malleable iron: Basic allowable stress value(s) for malleable iron at temperature shall be equal to the lowest of the followings: One fifth of the SMTS at room temperature and one fifth of tensile strength at temperature
4.5 2”
Piping Design Criteria-“Part-
4.5.1 “Pressure Integrity”-Piping Design: CASTING Q UALITY F ACTOR (E C): The casting quality factor (Ec) to be used for designing piping components are defined in ANSI B31.3 and are mentioned here for ready reference. However for designers, it is advised to refer codes requirements:
TABLE : B ASIC CASTING Q UALITY F ACTORS (E C) Inspection Method 1. 2.
3. 4.
5.
Factor (Ec) Visual surface examination of castings 0.85 Magnetic particle test or liquid penetration 0.85 test of surfaces of castings Visual + MPT + DPT 0.90 Ultrasonic testing of casting confirming no 0.95 Defect beyond 5 % of wall thickness Visual and ultrasonic testing conforming 1.00 no defect at all. 6. 6. Visual, MPT, DPT & Radiographic Test 1.00
W ELDED JOINT Q UALITY F ACTOR (E J ): Different welding processes with different welding joint grooves do the welding of the piping. Accordingly the quality and strength of the weld vary from each other. So welding quality factor (EJ) is mentioned here for reference only. For detail designing purpose, the code shall be referred. Longitudinal Weld Joint Quality Factor (Ej) Type of Joint Type of seam factor (Ej) 1. Furnace Butt Weld Straight 0.60
2. Electric Resistance Weld 0.85 3. Single Butt Weld: (Visual) 0.80 (Spot Radiography) Spiral (100% Radiography) 1.00 4. Double Butt Weld: (Visual) Spiral (Spot Radiography) Spiral (100% Radiography) 1.00
Straight or Spiral
Straight or Spiral Straight or 0.90 Straight or Spiral
Straight or 0.80 Straight or 0.90 Straight or Spiral
P IPING CONNECTION JOINTS : Commonly accepted methods for making pipe joint connections include butt-welded, socket welded, threaded and coupled. In normal condition piping, 2 inch in diameter and larger should be buttwelded. All piping 1 ½ inches or less in diameter should be socket welded. Threads should be tapered, concentric with the pipe, clean cut with no burrs, and conform to API STD 5B or ANSI B2.1. The inside of the pipe on all field cuts should be reamed. Thread compounds should conform to API Bulletin 5A2
4.5.2 Pipe Wall Thickness Design (i) Straight pipe under external pressure: After the allowable stress has been established for the application, the minimum pipe wall thickness required for pressure integrity is determined. For straight metallic pipe, this determination can be made using the requirements of ASME B31.3 Sec. 304 or other applicable codes. The determination of the minimum pipe wall thickness using the ASME B31.3 procedure is described below (see code for additional information). The procedure and following example described for the determination of minimum wall thickness using codes other than ASME B31.3 are similar and typically follow the same overall approach. Wall thickness and stiffening of the pipe under external pressure is designed in accordance with the boiler & pressure vessel code, section VIII, division I, UG-28 to UG-30. The required thickness of straight pipe is determined in accordance with the following equation: Tm A
=
t + Where: Tm = total minimum wall thickness required for pressure integrity, mm (in); t = pressure designed thickness, mm (in); A = Allowance, i.e. the sum of mechanical allowances plus corrosion allowance and erosion allowance, mm (in).
After determining the thickness of piping as per pressure and stress criteria, some allowances for thickness shall be added for corrosion, erosion and threads depth or groove depth. Also the wall thickness shall be increased to prevent overstressed damaged collapse or buckling due to super imposed loads from supports, Ice formation, backfill or other miscellaneous causes. Allowances include thickness due to joining methods, corrosion/erosion, and unusual external loads. Some methods of joining pipe sections result in the reduction of wall thickness. Joining methods that will require this allowance include threading, grooving, and swaging. Anticipated thinning of the material due to effects of corrosion or mechanical wear over the design service life of the pipe may occur for some applications. Finally, site-specific conditions may require additional strength to account for external operating loads, i.e. thickness allowance for mechanical strength due to external loads. The stress associated with these loads should be considered in conjunction with the stress associated with the pressure integrity of the pipe. The greatest wall thickness requirement, based on either pressure integrity or external loading, will govern the final wall thickness specified. Paragraph 3-4 details stress analyses. Using information on liquid characteristics, the amount of corrosion and erosion allowance necessary for various materials of construction can be determined to ensure reasonable service life. (ii) Straight Pipe Wall under internal pressure: Most of the piping components, now days, are designed based on Pressure-Temperature ratings. However, knowledge of designing the piping in case of any special material, in special conditions, the piping components’ thickness can be designed as mentioned above. These formulas are given here for designing the piping components’ thickness and for general information and knowledge of fresh Engineers. The overall formula used by ASME B31.3 for pressure design minimum thickness determination (t) is:
P Do t = 2 (SEPy)
Where: P = design pressure, MPa (psi); Do = outside diameter of the pipe, mm (in); S = allowable stress, MPa (psi), see Table A-1 from ASME B31.3,
and, E = weld joint efficiency or quality factor, y = dimensionless constant which varies with temperature, determined as follows: For t < Do /6, see table 304.1.1 from ASME B31.3 for values of y; For t > Do /6 or P/SE > 0.385, then a special consideration of failure theory, fatigue and thermal stress may be required. ASME B31.3. The pipe wall thickness required for a particular piping service is primarily a function of internal operating pressure and temperature. The standards under which ASTM A106 and API 5L seamless line pipe are manufactured permit a variation in wall thickness of 12-½ % below nominal wall thickness. It is usually desirable to include a minimum corrosion/mechanical strength allowance of 0.050 inches (1.27 mm) for carbon steel piping. A calculated corrosion allowance should be used after prediction of corrosion rate. For t
Where, d = Inside diameter of pipe (max.); c = as defined above for equation 1. S = allowable stress in psi in accordance with ANSI B31.3, Table 2.6.
Other Following Equations also can be used for calculation of Pipe Wall Thickness Required for a Particular Piping: Where, P =Internal Design Pressure in gauge. For t > D/6 or P/SE > 0.385, the calculation of
thickness need special consideration, i.e. theory of failure, effect of fatigue and thermal stress. PD t =
P (d + 2c) D P)
t=
2 SE
(SE - t =
[1-
]
2 P)
(SE +
2[SE - P (1 - y)]
Limitations: Small diameter, thin wall pipe is subject to failure from vibration or corrosion. In hydrocarbon service, the following should be met minimum, such as, pipe nipples ¾ inch diameter or smaller should be schedule 160 minimum; All pipe 3-inch diameter or smaller should be schedule 80 minimum. Completely threaded nipples should not be used. Table: Thread Allowances for Pipe Wall Thickness Calculation (Inch) Nominal pipe size ¼ - 3/8 ½-¾ 1 -2 2 ¼ - 20
Thread Allowance 0.05 0.06 0.08 0.11
4.6 3”
Piping Design Criteria-“Part-
4.6.1
Sizing of Liquid Line-Single Phase
The sizing for any piping system consists of two basic components, such as, (i) the flow velocity (fluid flow design) and (ii) pressure drop (pressure integrity design). Now, computer programs are used to facilitate piping sizing design. Fluid flow design determines the minimum acceptable diameter of the piping necessary to transfer the fluid efficiently. Pressure integrity design determines the minimum pipe wall thickness necessary to safely handle the expected internal and external pressure and loads.
Special Conditions for designing the Pipe Sizing: (i) Fluid Flow Velocity Condition: The maximum velocity of bubble point liquids shall be 1.2 m/s and for sub-cooled liquids shall be 2.4 m/s. For corrosive liquids these values may be reduced by fifty percent. A suction liquid line to a centrifugal pump velocities are usually between 0.3 to 2.13 m/s and the piping should be short and simple. For normal liquid service applications, the acceptable maximum velocity in pipes is 2.1 ± 0.9 m/s (7 ± 3 ft/s) with a maximum velocity limited to 2.1 m/s (7 ft/s) at piping discharge points. Higher velocities and unit losses can be allowed within this range when sub cooled liquid is flowing than when the liquid is saturated. Note that the longer payout times favour larger pipe diameters. Pipe of smaller size than pump discharge nozzle is not used. When determining line sizes, the maximum flow rate expected during the life of the piping should be considered rather than the initial flow, rate. It is also usually advisable to add a surge factor of 20 to 50 percent to the anticipated normal flow rate, unless surge expectations have been more precisely determined by pulse pressure measurements in similar systems or by specific fluid hammer calculation. The flow velocity in oil pipes should be within certain limits as shown in the following Table: Table: The flow velocity Oil Application Suction lines for pumps Suction lines for pump at low pressure Discharge lines for booster pumps
m/s
ft/s
< 0.5
< 1.6
0.1 – 0.2
0.3 - 0.65
1.0 – 2.0
3.3 - 6.5
Discharge lines burner pumps
for
< 1.0
< 3.3
However, the velocity should not exceed 15 feet/second at maximum flow rates, to minimize flashing ahead of the control valve. If, practical, flow velocity should not be less than 3 feet/second to keep the line swept clean of sand and other solids. At this flow velocity, the overall pressure drop in the piping will usually be small. Most of the pressure drop in liquid lines between two pressure vessels will occur in the liquid dump valve and/or choke. Flow velocity in liquid lines may be calculated using the following derived equation: Where: V1 = average liquid flow velocity, feet/second; Q1 = Liquid flow rate, barrels/day; d1 = pipe inside diameter, inches.
V1
=
0.012 Q1 d12
(ii) Pressure Drop Condition: Pressure drop, or head loss, is caused by friction between the pipe wall and the fluid, and by minor losses such as flow obstructions, changes in direction, and changes in flow area. In general, the pressure drops in pump suction lines shall be held below 4.5 kPa/100 m; and below 7.9 kPa/100 m in the case of liquid below the boiling point. Pressure drop (psi per 100 feet of flow length) for single phase liquid lines may be calculated using the following (Fanning) equation:
P =
0.00115 f Q12 S1 Where: P = pressure drop, psi / 100 feet; F = friction factor, dimensionless; Q1 = d15 liquid flow rate, barrels/day; S1 = liquid specific gravity (water = 1); d1 = pipe inside diameter, inches.
The friction factor, f, is a function of the Reynolds number and the surface roughness of the pipe. The modified Moody diagram may be used to determine the friction factor once the Reynolds number may be determined by the following equation: Pressure has dimensions of energy per unit volume. Therefore, the pressure drop between two points must be proportional to (1/2) ρ V2, which has the same dimensions as it resembles the expression for the kinetic energy per unit volume. We also know that pressure must be proportional to the length of the pipe between the two points L as the pressure drop per unit length is a constant. To turn the relationship into a proportionality coefficient of dimensionless quantity we can divide by the hydraulic diameter of the pipe, D, which is also constant along the pipe? Therefore, Where, Δp = the pressure loss due to friction (Pa or kg/ms2); the density of the fluid, ρ (kg/m3); the mean velocity of the flow, V (m/s), a = coefficient of laminar, or turbulent flow, f. In fluid dynamics, the Darcy–Weisbach equation relates the head loss or pressure loss due to friction along a given length of pipe to the average velocity of the fluid flow. The Darcy–Weisbach equation contains a dimensionless friction factor, known as the Darcy friction factor. The Darcy friction factor is four times the Fanning friction factor, with which it should not be confused. Head loss is calculated
with: Where, hf = the head loss due to friction (m); L = the length of the pipe (m); D is the hydraulic diameter of the pipe (internal diameter) (m); V is the average velocity of the fluid flow, (m/s); and g = the local acceleration due to gravity (m/s2); f = a dimensionless coefficient called the Darcy friction factor. Determination of pressure drop in a line should include the effect of valves and fittings. Manufacturer’s data or an equivalent length given may be used. A common method for calculating pressure drop is the Darcy-Weisbach equation. The head loss ‘hf’ expresses the pressure loss Δp as the height of a column of fluid, and is calculated as, Where ρ is the density of the fluid, the Darcy–Weisbach equation can also be written in terms of pressure loss. (iii) Hydraulic head: In fluid dynamics, head is a concept that relates the energy in an incompressible fluid to the height of an equivalent static column of that fluid. Head is expressed in units of height such as meters or feet. The static head of a pump is the maximum height (pressure) it can deliver. The capability of the pump can be read from its Q-H curve (flow vs. height). Head is equal to the fluid's energy per unit weight. Head is useful in specifying centrifugal pumps because their pumping characteristics tend to be independent of the fluid's density. There are four types of head used to calculate the total head in and out of a pump: Velocity head is due to the bulk motion of a fluid (kinetic energy); Elevation head is due to the fluid's weight, the gravitational force acting on a column of fluid; Pressure head is due to the static pressure, the internal molecular motion of a fluid that exerts a force on its container; Resistance head (or friction head or Head Loss) is due to the frictional forces acting against a fluid's motion by the container. A mass free falling from an elevation (in a vacuum) will reach a speed,
When Where, g is the acceleration due When arriving at elevation z = 0 or when we to gravity. rearrange it as a head. The term is called the velocity head, expressed as a length measurement. In a flowing fluid, it represents the energy of the fluid due to its bulk motion. The total hydraulic head of a fluid is composed of pressure head and elevation head. The pressure head is the equivalent gauge pressure of a column of water at the base of the piezometer, and the elevation head is the relative potential energy in terms of an elevation. The head equation, a simplified form of the Bernoulli Principle for
incompressible fluids, can be expressed as:
Where, h is the hydraulic head (Length in m or ft), also known as the piezometric head; ψ is the pressure head, in terms of the elevation difference of the water column relative to the piezometer bottom (Length in m or ft), and z is the elevation at the piezometer bottom (Length in m or ft).
PIPE SIZING D ESIGN Method-1: The optimum pipe size should be based on velocity limitations causing erosion or aggravating corrosion, which must be taken into consideration. Sometimes, the line size must satisfy process requirements such as pump suction line. Although pipe sizing is mainly concerned with pressure drop, sometimes for preliminary design purposes when pressure loss is not a concern, process piping is sized on the basis of allowable velocity. When there is an abrupt change in the direction of flow (elbow or tees), the local pressure on the surface perpendicular to the direction of flow increases dramatically. This increase is a function of fluid velocity, density and initial pressure. Since velocity is inversely proportional to the square of diameter, high velocity fluids require special attention with respect to the size selection. In Reynolds Number method, the relationship between pipe diameter, fluid density, fluid viscosity and velocity of flow according to Reynolds number is as follows: d. V. p Where, Re = Reynolds number Re = -------- dimensionless; μ (mu) = Viscosity at flowing μ temperature and pressure, in (cP); ρ (rho) = Density, in (kg/m3), d = internal diameter of pipe and V = velocity of fluid. Method-2: In hydraulic engineering applications, it is often desirable to express the head loss in terms of volumetric flow rate in the pipe. For this, it is necessary to substitute the following into the original head loss form of the Darcy–Weisbach equation Where, V = the average velocity of the fluid flow, equal to the volumetric flow rate per unit cross-sectional wetted area; Q is the volumetric flow rate; Aw is the internal cross-sectional wetted area of pipe. Method-3: For the general case of an arbitrarily-full pipe, the value of Aw will not be immediately known, being an implicit function of pipe slope, cross-sectional shape, flow rate and other variables. If, however, the pipe is assumed to be full flowing and of circular cross-section, as is common in practical scenarios, then Where, D is the
diameter of the pipe.
Pipe Velocity: A fluids flow velocity in pipes can be calculated, v = 0.4085 q / d2 -------
(1) in Imperial or American units.
Where, v = velocity (ft/s); q = volume flow (US gal. /min); d = pipe inside diameter (inches). v = 1.274 q / d2 ------(2) in SI units, Where, v = velocity (m/s), q = volume flow (m3/s), d = pipe inside diameter (m) Volume of discharge: For streamline flow through a smooth-walled circular pipe, the volume of liquid being discharged can be expressed with the Poiseulle's formula: V = π p r4 / 8 η l -------
(1)
Where, V = discharge volume flow (m3/s); p = pressure difference between ends of pipe (N/m2, Pa); r = internal radius of pipe (m); l = length of pipe (m) and η = viscosity of fluid. Pump Piping: A centrifugal pump converts the input power to kinetic energy in the liquid by accelerating the liquid by a revolving device - an impeller. The most common type is the volute pump. Fluid enters the pump through the eye of the impeller which rotates at high speed. The fluid is accelerated radially outward from the pump chasing. A vacuum is created at the impellers eye that continuously draws more fluid into the pump. The energy created by the pump is kinetic energy according the Bernoulli Equation. The energy transferred to the liquid corresponds to the velocity at the edge or vane tip of the impeller. The faster the impeller revolves or the bigger the impeller is, the higher will the velocity of the liquid energy transferred to the liquid be. This is described by the Affinity Laws. A catastrophic failure of a centrifugal pump can occur if the liquid within the pump casing is allowed to vaporize. To prevent flashing due to overheating of the fluid, a flow must be maintained through the pump to keep the liquid below saturation temperature. If a temperature rise of 15 0F is accepted in the casing - minimum flow through a centrifugal pump can be calculated as q = PBHP / 2.95 cp SG ---------- ----------------------------------------------
(1)
Where, q = minimum flow rate (gpm); PBHP = power input (BHP); cp = specific heat capacity (Btu/lb 0 F) and SG = specific gravity of the fluid. Bernoulli Equation): For a non-viscous, incompressible fluid in steady flow, the sum of pressure, potential and kinetic energies per unit volume is constant at any point. A special form of the Euler’s equation derived along a fluid flow streamline is often called the Bernoulli Equation:
Where, v = flow speed; p = pressure; ρ = density; g = gravity; h = height & h = h1 – h2 Pressure and Head: If the discharge of a centrifugal pump is pointed straight up into the air the fluid will pumped to a certain height or head is called the shut off head. This maximum head is mainly determined by the outside diameter of the pump's impeller and the speed of the rotating shaft. The head will change as the capacity of the pump is altered.
The kinetic energy of a liquid coming out of an impeller is obstructed by creating a resistance in the flow. The first resistance is created by the pump casing which catches the liquid and slows it down. When the liquid slows down the kinetic energy is converted to pressure energy. It is the resistance to the pump's flow that is read on a pressure gauge attached to the discharge line. A pump does not create pressure, it only creates flow. Pressure is a measurement of the resistance to flow. In Newtonian fluids (non-viscous liquids like water or gasoline) the term head is used to measure the kinetic energy which a pump creates. Head is a measurement of the height of the liquid column the pump creates from the kinetic energy the pump gives to the liquid. The main reason for using head instead of pressure to measure a centrifugal pumps energy is that the pressure from a pump will change if the specific gravity (weight) of the liquid changes, but not the head. Different Types of Pump Head: Total Static Head is total head when the pump is not running. Dynamic Head is total head when the pump is running. Static Suction Head is the head on the suction side, with pump off, if the head is higher than the pump impeller. Static Suction Lift is the head on the suction side, with pump off, if the head is lower than the pump impeller. Static Discharge Head is the head on discharge side of pump with the pump off. Dynamic Suction Head/Lift is the head on suction side of pump with pump on. Dynamic Discharge Head is head on discharge side of pump with pump on. The head is measured in either feet or meters and can be converted to common units for pressure as psi or bar. It is important to understand that the pump will pump all fluids to the same height if the shaft is turning at the same rpm. The only difference between the fluids is the amount of power it takes
to get the shaft to the proper rpm. The higher the specific gravity of the fluid the more power is required. Centrifugal Pumps are "constant head machines", since pressure is a function of head and density. The head is constant, even if the density changes. The head of a pump in metric units can be expressed in metric units as: h = (p2 - p1 )/(ρ g) + v2 2 /(2 g)
-----------------------------------------
(1)
Where, h = total head developed (m); p2 = pressure at outlet (N/m2); p1 = pressure at inlet (N/ m2); ρ = density (kg/m3); g = acceleration of gravity (9.81) m/s2; v 2 = velocity at the outlet (m/s). The Hazen-Williams formula is empirically derived and is limited to use with fluids that have a kinematics viscosity of approximately 1.12 x 10-6 m2 /s (1.22 x 10-5 ft /s), which corresponds to water at 15.6 0C (60 0F), and for turbulent flow. Deviations from these conditions can lead to significant error. The Hazen-Williams coefficient, C, is independent of the Reynolds number. Values of C for various pipe materials are taken from the reference book. Full Pipe Flow: The Chezy-Manning Equation is occasionally applied to full pipe flow. The use of this equation requires turbulent flow and an accurate estimate of the Manning factor, n, which varies by material and increases with increasing pipe size. The reference book provides values of n for various pipe materials. The Chezy-Manning equation is: Where, hL = head loss, m (ft); V = fluid = velocity, m/s (ft/s); n = Manning factor; (L a = empirical constant, 1.0 for SI units (2.22 for IP units); Le = equivalent length of pipe for minor losses, m (ft); a (Di/4)4/3 L = length of pipe, m (ft); Di = inside pipe diameter, m (ft). V2 n2 hL
Le )
Pump Suction Line: Reciprocating, rotary and centrifugal pump suction piping systems should be designed so the available Net Positive Suction Head (NPSH) at the pump inlet flange exceeds the pump required NPSH. Additionally, provisions should be made in reciprocating pump suction piping to minimize pulsation. Satisfactory pump operation requires that essentially no vapour be flashed from the liquid as it enters the pump casing or cylinder. Eccentric Reducer with topside in straight line is used to avoid vapour flashing. In a centrifugal or rotary pump, the liquid pressure at the suction flange must be high enough to overcome the pressure drop between the flange and the entrance to the impeller vane (or rotor) and maintain the pressure on the liquid above its vapour pressure. Otherwise, cavitations will occur. In a reciprocating unit, the pressure at the suction flange must meet the same requirement; but the pump required NPSH is typically higher than for a centrifugal pump because of pressure drop across the valves and pressure drop caused by pulsation in the flow. Similarly, the available NPSH supplied to the pump suction must account for the acceleration in the suction piping caused by the pulsating flow, as well as the friction, velocity and static head. The necessary available pressure differential over the pumped fluid vapour pressure may be defined as Net Positive Suction Head available (NPSHa). It is the total head in feet absolute determined at the suction nozzle, less the vapour pressure of the liquid in feet absolute. Available NPSH for most
pump applications may be calculated using following equation. NPSHa = h p - h vpa + h st - h f - h vh - ha Where: h p = absolute pressure head due to pressure, atmospheric or otherwise, on surface of liquid going to suction, feet of liquid; h vpa = the absolute vapour pressure of the liquid at suction temperature, feet of liquid; h st = static head, positive or negative, due to liquid level above or below datum line, i.e. Centreline of pump in feet of liquid; h f = friction head, or head loss including entrance and exit losses due to flowing friction in the suction piping, (feet of liquid).
V12 hvh
= velocity head = 2g
(feet of liquid.)
Where, ha = acceleration head, feet of liquid; V1 = velocity of liquid in piping, feet/second; g = gravitational constant (usually 32.2 feet/second2) For a centrifugal or rotary pump, the acceleration head, ha, is zero. For reciprocating pumps, the acceleration head is critical and may be determined by the following equation from the Hydraulics Institute: L V1 Rp C ha = K g
Where: ha = acceleration head, feet of liquid; L = length of suction line, feet (actual length, not equivalent length); V1 = average liquid velocity in suction line, feet/second; Rp = pump speed, revolutions/minute;
And, C = empirical constant for the type of pump = 0.200 for simplex double acting = 0.200 for duplex single acting = 0.115 for duplex double acting = 0.066 for triplex single or double acting = 0.040 for quintuples single or double acting = 0.028 for septuplet single or double acting; and K = A factor representing the reciprocal of the fraction of the theoretical acceleration head which must be provided to avoid a noticeable disturbance in the suction piping = 1.4 for liquid with almost no compressibility (deareated water) = 1.5 for amine, glycol, water = 2.0 for most hydrocarbons = 2.5 for relatively compressible liquid (hot oil or ethane); and g = gravitational constant (usually 32.2 feet/second 2). Following table be used to determine preliminary suction and discharge line sizes: Table: Typical Flow Velocities Suction Velocity, ft/s
Discharge ft/s
Velocity,
Centrifugal pumps:
2–3
6–9
4.6.2
Sizing of Gas Line-Single Phase
a. Process Lines: When pressure drop is a consideration in the lines connecting two components operating at essentially the same pressure, etc., single-phase gas lines should be sized on the basis of acceptable pressure drop. The pressure drops listed in following table have been found by experience to be an acceptable balance for short lines, when capital costs for pipe and components and operating costs are considered. When velocities in gas lines exceed 60 feet/second, noise may be a problem. Gas velocities may be calculated using the following derived equation (neglecting compressibility); 60 Qg Where: Vg = gas velocity, feet/second; d1 = pipe inside diameter, inch; Qg = gas flow rate, million cubic feet/day at 14.7 psia and 60 0 F;
T Vg= d12
And. T = operating temperature, 0 R; P = operating pressure, psia Table: Acceptable Pressure-Drop for Single Phase Gas Process Line Operating Pressure (psig) (psi / 100 feet) 0 – 100 101 – 500 0.49 501 – 20
Acceptable Pressure Drop 0.05 - 0.19 0.2 0.5 - 1.2
Compressor Lines: Reciprocating and centrifugal compressor piping should be sized to minimize pulsation, vibration and noise. The selection of allowable velocities requires an engineering study for each specific application. Very Low Pressure Lines: Pressure drop calculations may be necessary in very low operating pressure systems. The following equation (Spitzglass) may be used for operating pressures less than 1 psig.
4.6.3
Sizing of Liquid / Gas LineTwo Phase
Erosional Velocity: Flow lines or process headers and other lines transporting gas and liquid in twophase flow should be sized primarily on the basis of flow velocity. Flow velocity should be kept at least below fluid Erosional velocity. If solids (sand) production is anticipated, fluid velocities should be reduced accordingly. The Velocity above which erosion may occur can be determined by the following empirical equation: C
Ve = fluidErosional velocity, Ve feet/second;C = empirical constant = 125 for intermittent service = 100 for continuous service; and Pm = (Pm) gas/liquid mixture density at flowing pressure and temperature, lbs/ ft3
=
The density of the gas / liquid mixture may be calculated using the following derived equation.
Sg P =
12409 S1 P + 2.7 R Where: P = operating pressure, psia; S1 = liquid specific gravity (Water=1; use average Gravity Pm for hydrocarbon-water 198.7 P + R T mixtures); R = gas/liquid ratio, ft3/barrel; T = operating temperature, 0 R;
And, Sg = gas specific gravity (air = 1). Minimum Cross Sectional Area: Once Ve is known, the minimum cross sectional area required to avoid fluid erosion may be determined from the following derived equation. RT 9.35
+ 21.25P
A =
Where: A = minimum pipe cross - sectional flow area required, in2/ 1000 barrels liquid per day; T = 535 0 R; R = gas/liquid ratio, ft3/barrel; P = operating pressure, psia;
Ve Minimum Velocity: If possible, the minimum velocity in two-phase lines should be about 10 feet per second to minimize slugging of separation equipment. This is particularly important in long lines with elevation changes.
Pressure Drop: The pressure drop in a two-phase steel piping system may be estimated using the following equation, which was developed from Fanning’s fluid flow equation using an average friction factor of 0.0038. This equation is limited to a total pressure drop of 10% of inlet pressure to minimize the error resulting from assuming pm constant: Where, P = Pressure drop, psi / 100 feet; d1 = pipe inside diameter, W2 inches; pm = gas /liquid density at P = flowing pressure and temperature, lbs/ft3 ( calculate as shown in equation above); W = total liquid plus vapour rate, lbs/hr.
6.9 x 10
–6
d15 pm
W may be calculated using the following derived equation: W = 3180 Qg Sg + 14.6 Q1 S1 Where: Qg = gas flow rate, million cubic feet/day (14.7 psia and 60 0 F); Sg = gas specific gravity (air = 1); Q1 = liquid flow rate, barrels /day; S1 = liquid specific gravity (water = 1)
PIPE SIZING FOR O FFSHORE PLANT- SINGLE PHASE GAS FLOW The optimum pipe size should be based on minimizing the sum of energy cost and piping cost. However, velocity limitations causing erosion or aggravating corrosion must be taken into consideration. Sometimes, the line size must satisfy process requirements such as pump suction line. Although pipe sizing is mainly concerned with pressure drop, sometimes for preliminary design purposes when pressure loss is not a concern, process piping is sized on the basis of allowable velocity. When there is an abrupt change in the direction of flow (as in elbow or tees), the local pressure on the surface perpendicular to the direction of flow increases dramatically. This increase is a function of fluid velocity, density and initial pressure. Since velocity is inversely proportional to the square of diameter, high velocity fluids require special attention with respect to the size selection. 2 P1P2 Pave = Average Gas Pressure = — { P1 + P2 - ——— } 3 P1 + P2 In vapour systems, the use of rule of thumb or approximate sizing methods can lead to critical flow and subsequent vibration and whistling. With two-phase systems, improper sizing can lead to slug flow with its well known vibration and pressure pulsations. With both vapour and two-phase systems, approximate calculations often neglect the importance of momentum on total pressure drop; the result being that, pressure drop available for controllability, is reduced; and rigorous calculations to determine pressure drop involving trial and error should be
performed by computers. The problem is further complicated when a diameter is to be found which will produce a specified pressure drop or outlet velocity for a given flow. In this situation additional trial and error is required to determine the proper diameter. The design problem as described above is correctly defined as line sizing. In general an evaluation of the total system equivalent length must be made based on fittings, valves, and straight line in the system. In addition, fitting and valve losses are not constant, but are functions of diameter. A preliminary line sizes must often be selected before an accurate knowledge of the system equivalent length is available, spool check calculations are required before final specifications for prime movers can be written on final diameter, chosen. Water Flow: The pressure loss for water flow shall be calculated by Hazen- Williams’s formula. The Hazen-William’s relationship is one of the most accurate formulas for calculation pressure loss in water line (see Appendix C for Hazen-William’s constant C). For the design of new water pipelines, constant "C" is taken as "100". The Hazen-s formula is as follows: 100 Qw 1.85 hf = 2.25 x 104 Le {--------- }1.85 x {---------- } C d 4.865 Where, C = Hazen-Williams constant; d = Inside diameter of pipe, in (mm); hf = Head loss due to friction, in (mm); Le = Equivalent length of pipe, in (m); and Qw = Vapour flow rate, in (m³/h). Pump Suction Lines: Allowable pressure drops is determined by formula: ΔP = 9.835 S [H-(NPSHR + α)] + (P1-Pv) Where: ΔP is friction loss in piping to pump inlet, in (kpa); S is relative density (Water = 1); H is height from datum to pump centre, in (m) (the term "Datum" refers to the bottom tangent line in the case of vertical vessels and to the bottom level in the case of horizontal vessels); NPSHR is net positive suction head required, in (m); α(alpha) is 0.305 m (1 ft) for liquid at boiling point and 0.2134 m for liquid below boiling point; P1 is pressure working on suction liquid surface (kPa); Pv = vapour pressure of liquid at suction temperature (kPa). In cases where permanent strainers are to be provided a minimum pressure drop of 3.45 kPa (0.5 psi) shall be added in the case o f dirty service. No addition is required in the case of clean service. The equivalent length to be used for pressure drop calculations shall be assumed to be 46 m (150 ft). Cooling Water: Cooling water discharge headers are usually sized with unit pressure losses in decimals of 7 kPa (1 psi). An economical comparison is justified with large diameter piping, where most of the pump pressure is used for pipe and equipment resistance. Of course, piping costs increase with diameter while utility costs decrease. Between alternate designs the best size can be determined by adding the total cost of utilities over the period of capital payout to the capital cost of each installation. The lowest over-all figure will give the most economical solution. Amine solution: The following limitations should be considered. For carbon steel pipe: Velocity for Liquid = 3 m/s; Velocity for Vapour-liquid = 30 m/s; Velocity for stainless steel pipe, Liquid = 9 m/s; and Velocity for Vapour-liquid = 36 m/s Ammonium bisulphate (NH3-H2S-H2O) solution: Aqueous solutions of ammonium bisulphate produced in the effluent line of hydro-cracking, hydro-treating processes often cause rapid erosion-
corrosion of carbon steel pipes, especially for nozzles, bend, tees, reducer and air cooler tube inlet parts after water injection points. Care must be taken not to exceed the highest fluid velocity in pipe tubes. Gravity flow: i) Side cut draw-off: In cases where no controller is provided for the liquid level in the liquid draw-off tray, the flow velocity in the first 3 meters of the vertical line shall be less than 0.762 m/s. This value is intended for vapour-liquid separation based on the particle diameter 200 micrometers (1000 micron = 1 mm) in cases where the operating pressure is high or the difference between the vapour and liquid densities is small: Q CV = ------------------√ {ΔP/S.G}
Where: CV = the flow coefficient or pressure loss coefficient; Q = flow rate, GPM; ΔP = pressure drop, psi; and S.G = specific gravity of the fluid.
The line size shall be also checked that the control valve size may not become larger than the line size. Steam condensate lines: This is a line from heat exchanger to steam trap or control valve. The pressure drop in this line shall be smaller than 11.3 kPa/100 m (0.1kg/cm2/100 m) and shall be checked that no condensate may vaporize therein. ii) Line from steam trap or control valve to following vessel - Steam condensate return lines must be sized to avoid excessive pressure loss. Part of the hot condensate flashes into steam when it is discharged into the condensate return system. 354 x W x VR (hc - The flow velocity "V” calculated by the following equation must be hR ) V = --------------------------- limited to 1524 m/min to prevent erosion. --------d2xL Flare headers: Flare headers shall be designed so that the maximum allowable velocity does not exceed 50 percent of critical velocity, a figure mostly practiced by design companies.
SINGLE PHASE GAS FLOW: 1. In general when considering compressible flow, as pressure decreases along the line so does the density (assuming isothermal flow). A variation in density implies variation in Reynolds number on which the friction factor is dependent. A rigorous calculation of pressure loss for long pipeline involves dividing it into segments, performing the calculation for each segment (considering variable parameters) and integrating over the entire length. For process piping however, since pipe lengths are generally short, a rigorous calculation would not be necessary and the equation outline below are considered adequate. 2. As mentioned above for estimating pressure drop in short run of gas piping such as within plant or battery limit, a simplified formula for compressible fluids is accurate for fully turbulent flow, assuming the pressure drop through the line is not a significant fraction of the total pressure (i.e., no
more than 10%). 3. The Darcy formula 62530 fD x Wg2 is used for calculation ΔP100 = --------------------------of pressure loss in bar/100 m process gas lines as ρg x d5 here: 4. Steam Flow: D + 3.6 2 Babcock formula shall W x L be used to calculate ΔPf = 3.63 x 10-8 { ------------- } pressure drop in steam ------------------lines: d6 ρ
---
Where: ΔPf is frictional component of pressure drop, psi. 5. Sampling and Injection Connections: Connections may be desired for chemical injection and for obtaining samples. If installed, they should be ½ inch minimum nominal size and include a closecoupled block valve. Associated piping should be stainless steel tubing or heavy wall pipe and should be well protected to minimize the possibility of damage. A spring-loaded ball check valve should be close-coupled to the block valve on injection lines. Chokes: Chokes are normally installed to control the flow. Choke types include adjustable, positive and combination. The number and location of chokes depend on the amount of pressure drop taken, fluid, flow rate, and solids in the stream. Usually, if only one choke is used, it should be located near the source of flow. Additional chokes may be located in between the headers. The following general guidelines should be considered regardless of the number of chokes or their location: Choke bodies should be installed in a manner that will permit easy removal and trim changes. The downstream flow passage within ten nominal pipe diameters should be free of abrupt changes in direction to minimize flow cutting due to high velocity. Outlet connections should be examined to determine if their bore should be tapered to improve flow patterns. Suitable provisions should be provided to isolate and depressurise the choke body when changing trim, removing trash, etc. Flow line Pressure Sensor: The installation of a Flow line sensor should be in accordance with API RP 14C. Further, the connection should be ½ inch minimum nominal size and located to minimize the possibility of plugging and freezing. Connections on the bottom of the line or in turns should be avoided. Sensors should be installed with an external test connection and block valve. Sensing lines should be stainless steel and secured to prevent whip in case of severance. Flow line Temperature Sensor: The installation of a Flow line sensor should be in accordance with the Codes. Further, the connection should be 1½-inch minimum nominal size and located to minimize the possibility of plugging and freezing. Connections should be on the top of the header line. Connections in turns should be avoided. Sensors should be installed with an external test connection and with Thermo well. Sensing lines should be stainless steel and secured to prevent whip in case of severance.
Flow line Orifice Fitting: A Flow line orifice fittings may be desirable in gas service for either a monitoring aid or as a means of production allocation. Flow Line Heat Exchanger. If a Flow line heat exchanger is used, the following provisions should be considered; Connections should be arranged so that the exchanger bundle may be pulled without having to cut or weld on inlet and outlet piping. Exchanger U-bends, if used, should either be exposed to the exterior, or easily accessible for non-destructive testing. A Flanged end heat exchanger shell of a standard dimension is desirable so that bundles can be interchanged, or pulled and repaired. A relief system should be provided. Flow line Check Valve: A Flow line check valve should be installed to minimize back flow due to inadvertent switching of a low-pressure system into a higher-pressure system, or in case of line rupture. Flow line Support: Flow lines should be supported and secured to minimize vibration and to prevent whip. When designing Flow line supports, it should be recognized that even though the equipment may be fixed to the foundations, there is a possibility of independent equipment movement due to heat or expansion. Sampling: Sample piping should be as short as possible, protected from physical damage, and easily accessed by operators. Sample connections are made on feed, intermediate and product streams for process control. Process engineers are consulted in order to determine the number and location of sample ports. It is recommended that the minimum size connection to either the process equipment or the piping be 15 mm (¾ in). If the sample line is longer than a meter (approximately 3 feet), two valves are installed in the sample line. The first valve is located as close to the actual sample point as possible. The second valve is a final block valve and should be located near the end of the sample piping. The valves should be quick opening, either gate or ball type, and all materials of construction should meet the application. Sampling Valves: Materials of construction for sample ports and sample valves match the piping system and the required application. Coordination with CEGS 01450, Chemical Data Quality Control, is necessary to ensure proper sampling. Valves for sampling process streams should be provided at appropriate locations. Valves should be located so that representative samples will be obtained. Sample valves may be used in conjunction with sample catchers or with sample tubes, which extend into the centre of the pipe. Consideration should be given to the quality and condition of the stream at each location. Valve design and piping should allow cleaning or rotting of valves, which may become plugged with solids. Valves subject to large pressure drops maybe quickly cut out. Double valve and proper sampling procedures can minimize such problems. Sample valves are usually ½ inch austenitic stainless steels. Piping Manifolds: Manifold branch connections should be in accordance with ANSI B31.3. If weldolet are used, care should be taken to ensure the entrance hole is smooth and free of burrs after it is welded in place. The terminus of the Manifold runs should be blind flanged to provide a fluid cushion area and for possible future expansion. The piping arrangement should provide easy access to each manifold valve for operational purposes and easy removal. In initial design of the piping, it may be desirable to make provisions for the future installation of valve operators. Process Vessel Piping: Typical three-phase process vessel with standard accessories and many
optional items is shown on Figure 6.2. Different vessels are required for different functions in processing. However, all of the flow streams to and from a vessel are generally handled in a similar manner. All of the items shown on Figure 6.2 may not be needed, but are shown in their recommended location when required. Accessories should be installed to permit ready removal for repairs or replacement. Safety devices should be capable of being tested in place. Utility Systems: This section deals with pneumatic, firewater, potable water, sewage and related systems. Pneumatic Systems: Pneumatic systems are required to provide a dependable supply for pneumatically operated components. All pipe, tubing and fittings 3/8 inch nominal size and smaller should be AISI 304 or 316 stainless steel, with 0.035 inch minimum wall thickness where exposed to the atmosphere. Synthetic tubing may be used in weatherproof enclosures or in fire loop safety systems. Fire loop safety systems should be in accordance with API RP 14C. Piping should be installed in a manner that will minimize low points or traps for liquid. Outlets, from vessels and piping should be from the top of the system and drains from the bottom. Blow down provisions should be included in the piping systems to allow removal of condensation. Pneumatic systems should be tested. Air Systems: Main air headers should be 2-inch nominal diameter, utilizing corrosion resistant material such as threaded and coupled galvanized steel. Care must be exercised in locating air compressor suctions to preclude the introduction of gas or hydrocarbon vapours into the system. No crossovers, whereby air and gas could be intermixed, should be allowed anywhere in the system. Gas Systems: For gas systems, vents and relief valves should be taken to a safe location, if it is determined that the volumes being vented could create an abnormal condition. The gas source chosen should be the driest gas available. The following guidelines may be helpful in designing an instrument gas or a fuel gas system: Taking a significant pressure drop, an external heat source may be required to prevent freezing if the gas is not dehydrated. The gas should be expanded to a separator to prevent hydrates and liquids from entering the system piping. The inlet and outlet pressure rating of pressure reduction devices should be carefully considered. If the outlet pressure rating is less than the inlet source pressure, a relief device should be close-coupled to the reduction device. Parallel reduction devices should be considered to maintain system operation in the event the primary device fails.
4.6.4
Pipe Sizing in Steam Systems
There are two types of losses, such as (1) Major Loss and (2) Minor Loss in steam distribution systems. The pressure drop in the distribution of steam system is the pressure difference between the initial pressure at the boiler, and the final pressure received, at the steam consumer, at the end of the line and can be expressed as: p = pj - pk pt = pmajor + pminor
p = available pressure drop (Pa (N/m2); pj = initial or boiler pressure (Pa (N/m2)) pk = final pressure (Pa (N/m2))
The total pressure drop in the distribution system is a result of friction in pipe (pt ), Where, pt = total pressure drop in the system (Pa (N/m2)); pmajor = pressure loss in pipes due to friction (Pa (N/m2)); pminor = pressure loss in fittings (Pa (N/m2)). Friction - Major Loss: The pressure loss due to friction in a low-pressure steam distribution system can be expressed as: pmajor = pa l pa = pipe friction resistance per unit length of pipe (Pa/m (N/m2/m)) l = length of pipe (ft, m) Loss due to Fittings - Minor loss can be expressed as: pminor = ξ 1/2 ρ ξ = minor loss coefficient; pminor = v2 pressure loss (Pa (N/m2)); ρ = Density (kg/m3); v = flow velocity (m/s) As a rule, the total pressure drop is about 5 -10 % of initial pressure per 100 m pipe. Recommended Velocities in Steam Systems: The steam velocities in steam distribution systems should be within certain limits to avoid excessive wear and tear of the pipe and as given, such as, Exhaust steam - 20 to 30 m/s; Saturated steam - 30 to 40 m/s; Superheated steam - 40 to 60 m/s; Saturated Steam - high pressure - 25 to 40 m/s; Saturated Steam - high pressure - 30 to 40 m/s; Saturated Steam - high pressure - < 50; and Saturated Steam - high pressure - < 25. Selection of Steam Pipes (kg/h)-Size: Steam is a compressible gas where the mass flow capacity of the pipelines depends on the steam pressure. The following Table gives the suitable size of steam pipes, where pressure is in bar, velocity in m/s and capacity in kg/h. A speed of 25 m/s is in general sufficient for saturated steam applications.
Fig: Manifold with Control Vale
Fig: Air Cooler Piping Manifold
Fig: Reciprocating Compressor Piping Branch connections: When the branch line size is equal size or greater than one half of nominal size of run pipe, branch connections in welded lines should be butt weld straight tees or reducing tees. If the branch line is 2-inch nominal pipe size or larger, but less than 1.5 times of the nominal run size, “weldolet” may be used. Branch lines 1 ½ inch nominal pipe size and smaller should be connected to runs size 1 ½ inch nominal and smaller, with socket weld tees. It shall be connected to run size 2 inch nominal and larger with “Sockolet” or equivalent or socket weld couplings. Stub-in connection should, generally, not be used. The disadvantages of a non-reinforced stub-in connection are numerous. Sharp changes in section and direction and junction introduce severe stress intensification. Reinforcement using a pad or a saddle improves the situation somewhat. However, the finished connection is difficult to examine for welding and other defects. The stress-intensifying defect makes sub-ins connection a poor choice for critical services for those with severe cyclic operating conditions and loading. If, stub-in connections are necessary, the use of full encirclement saddles is recommended. Branch connection in screwed piping systems should be made using straight tees and swage reducers, or reduced outlet tees. All screwed piping systems should be isolated from welded piping systems by block valves.
Fig: Heat Exchanger Piping Fire Water systems: Fire water systems should be constructed of carbon steel pipe. Accessibility during a fire should be considered when locating fire hose stations and/or turrets. In the determination of required flow rates, consideration should be given to the surface area, location of the equipment and to the maximum number of discharge nozzles, which could be in use simultaneously. See NFPA. (National Fire Code, Volumes 6 and 8)
Fig: Column and Towers Piping Potable water systems: Threaded and coupled galvanized steel pipe and bronze valves should generally be used in potable water service. Copper pipe may be used within the confines of buildings. Toxic joint compounds should be avoided. If water makers are used, consideration should be given to potential contamination of the water from heating sources. When potable water is supplied to other facilities such as engine jacket water makeup, etc., care should be exercised to prevent contamination from backflow. Sewage Systems: Interior sewage piping, such as in living quarters areas, should be carbon steel, cast iron pipe with Babbitt, or lead sealed joints or PVC properly supported. Exterior piping may be carbon steel, cast iron, fibreglass or PVC (when properly supported and protected from sunlight). All piping should be well supported and have a minimum slope of 1/8 inch per foot. Down pipes in the living quarters, etc. should be a minimum of 2-inch nominal diameter and all other piping a minimum of 4-inch nominal diameter. The system should be designed with adequate clean-out provisions. Discharge lines from sewage treatment plants should terminate near water level and contain readily accessible sampling connections. Care should be exercised in locating vents.
Heating Fluid and Glycol Systems: The paramount safety consideration in the design of heating fluid systems is containment of the fluid for personnel protection and fire prevention. All piping, valves and fittings should be in accordance with API RP14E and ANSI B31.3 except that flanges for other than low pressure steam and hot water systems should be a minimum of ANSI 300 lb to minimize leakage. Piping should be designed for thermal expansion and thermal insulation. If the process side of a shell and tube heat exchanger has a higher operating pressure than the design pressure of the heating fluid side, a relief device must protect the heating fluid side. The location of the relief device depends on the actual design of the system. If possible, the relief device should be located on the expansion (surge) tank, which will serve as a separator. A relief device may also be required at the heat exchanger. Consideration should also be given to tube failure in heat exchangers where the operating pressure of the heating fluid system exceeds the test pressure of the process system. The effect of mixing hot fluids with cold fluids should be considered when determining how to dispose of the discharge of a relief device on a heat exchanger. A separate scrubber may be required heating systems (except hot water or steam) should preferably be pneumatically tested. If hydrostatically tested, provisions should be made for removal of all water from the system before placing in service. Additionally, any water remaining after draining should be removed at start-up, by slowly bringing the system to 212 0 F and venting the generated steam. Care should be taken to ensure that each branch of the system has circulation during this period. The exhaust stream from a glycol Reboiler contains steam and hydrocarbon vapours. Caution should be exercised in the design of Reboiler exhaust piping to prevent backpressure, ignition and condensation problems.
Fig: Centrifugal Pump Piping Pressure Relief and Disposal Systems: Pressure relief and disposal systems are required to prevent over pressure of process components and to dispose of the relieved product in a safe manner. Some possible causes of over pressure are downstream blockage, up-stream control valve malfunction, and external fire. The commonly used safety relief devices are the conventional spring loaded relief valve, the balanced bellows spring loaded relief valve, the pilot operated relief valve, the pressure- vacuum relief valve and the rupture disc. For a complete description, operation, sizing, pressure setting and application guide, see ASME Section VIII, API RP 520 Part I, API RP 521 and API RP 14C. Relief devices in gas or vapour service should normally be connected to either the vessel vapour space or the outlet piping. They should be located upstream of wire mesh mist extractors. Liquid relief devices should be located below the normal liquid level. If vessels with the same operating pressure are in series, a relief device set at the lowest design pressure in the system may be installed on the first vessel. If any remaining vessel can be isolated, a relief device sized for fire or thermal expansion is required. Relief devices should be located so they cannot be isolated from any part of the system being protected. Relief Device Piping: If a spring-loaded relief valve is used, it may have a full opening block or check valve upstream plus an external test port for testing and calibrating. If not, it will be necessary to remove the valve for testing. If a pilot operated relief valve is used, the upstream valve is not
required for testing purposes. Should the relief device have to be removed, process systems connected to a common relief header must be shut down. Alternatively, a full opening block or check valve may be installed downstream of relief devices if connecting to a common relief header. All block valves installed either upstream or downstream of relief devices should be equipped with locking devices and operated in accordance with ASME Section VIII, Appendix M. Piping on the exhaust side of relief devices should be designed to minimize stress on the device. The piping should also be designed to withstand the maximum backpressure to which it could be subjected. API Spec 526 covers the allowable working pressure of relief valves. Relief (Disposal) System Piping: The relief system and piping should be designed to dispose of the relieved product in a safe and reliable manner. The system and piping should be designed to prevent backpressure from occurring at any point in the system that would reduce the required relieving capacity of any of the pressure relieving devices. The maximum possible backpressure at each relief point should be determined. This is particularly important where two or more relief devices may relieve simultaneously into the same disposal system. The materials, fittings, welding and other design criteria should conform to the respective parts of the RP 14E and to API RP 520, PART II. Vent or flare structures should be designed to prevent buckling caused by wind moment. Vent or flare structures should preferably be installed on the downwind side of the plant. In determining height and distance from the plant, consideration should be given to accidental ignition due to lightning, falling burning fluid, and heat radiation. When hydrocarbon vapours are discharged into the atmosphere, mixtures within the flammable range will occur downstream of the outlet. To determine the location of this flammable mixture and the intensity of the heat should the mixture become ignited, refer to API RP 521 and API Proceedings, Vol. 43 (III) (1963), Paged 418-433. When toxic vapours are discharged into the atmosphere, systems should be designed in accordance with EPA A P-26, ‘Workbook of Atmospheric Dispersion Estimates’. If feasible, all relief systems should be designed for a minimum pressure of 50 psig in order to contain flashback. In most cases, vents from atmospheric pressure equipment should be equipped with flame arrestors for flashback protection. Flame arrestors are subject to plugging with ice and should not be used in cold climates. Flame arrestors should be inspected periodically for paraffin build-up. Drain Systems: All low points in liquid process piping systems should be provided with drain or blow-off valves. These valves allow flushing of sediments from, or draining of, the entire lines. The most common valves used for draining purposes are gate valves. If rapid draining is not important, globe valves may also be used, provided that sediment accumulation is not a concern. Pipelines 50 mm (2 in) and smaller should use 15 mm (½ in) valves, as a minimum size. Pipelines that are 65 mm (2½ in) or greater should have a minimum valve size of 20 mm (¾ in). Drain systems should be designed to collect and dispose of contaminants from all sources. A good drain system prevents contaminants from spilling overboard; prevents the accumulation of flammable liquids on the ground or pans; and promotes good housekeeping practices. Pressure Drains: When pressure (closed) drains from pressure vessels are used, they should be piped directly to the disposal facilities, independent of the gravity drains, to prevent the introduction of fluids from the pressure drains into the gravity drains. The design pressure of the interconnecting piping and drain valve on each process component should correspond to the highest working pressure process component in the system. Piping should be in accordance with Section ANSI B31.3. A
separate closed drain system should be provided for hydrogen sulphide service to permit safe disposal of the fluids. Gravity Drains: Storm water drain or open drain is usually drained by gravity to the disposal facilities. A wide variety of materials may be satisfactory for this service. Consideration should be given to minimizing bends and flow restriction in the system. Piping should be installed with a downward slope on the order of 1/8 inch per foot. In some cases, it may be necessary to install runs in a horizontal plane, but in no circumstances should up-slopes be permitted. Clean-out connections should be provided. Special Requirements for Sulphide Stress Cracking Service: Fitting and flange materials, as normally manufactured, are generally satisfactory for sulphide stress cracking service with the additional stipulation that they be modified to conform to the requirements of NACE MR – 01 – 75. ASTM A 194, Grade 2 M, nuts and ASTM A 193, Grade B 7 M, bolts are generally satisfactory for pipe flanges. Consideration should also be given to torque requirements during installation. Type R and RX rings should be made of annealed AISI 316 stainless steel Erosion Prevention: To minimize erosion where sand production is expected, short radius pipe elbows should not be used. All turns in flow lines should be made with tees and weld caps (or blind flanges), cap tees 0r flow tees, or long radius bends, (minimum bending radius should be 1.5 times dia. in accordance with ANSI B 31.3). Noise: In the design of plant piping systems, provisions should be made to protect personnel from harmful noise. Problems and solutions are discussed in depth in API Medical Research Report EA 7301, Guidelines on Noise. A general discussion of noise related to piping systems is included in this section. 1. Noise in a piping configuration is caused by the turbulence of a fluid passing through the system. Turbulence is created downstream of restricted openings and increases as the fluid velocity increases. Most noises in piping systems may be attributed to the various types of control valves. The sound pressure level may be calculated for control valves from formulas and data supplied by the various manufacturers. 2. The fundamental approach to noise control in piping system should be to avoid or minimize the generation of harmful noise levels. Methods that may be effective in avoiding such levels in piping systems include: Use acoustic insulation and / or shielding around pipe and fittings to absorb or isolate sound. Use flow stream silencers for extreme cases. Minimize fluid velocities: The noise levels generated by the recommended velocities in Section 2 of API RP14E should be acceptable. Select control valves of a type or with special trim to minimize noise. Methods that may be effective in minimizing noises in piping systems include: Avoid abrupt changes in flow direction. Use venturing (conical) type reducers to avoid abrupt changes in flow pattern. Use flow-straightening vanes to reduce large-scale turbulence. Use extra heavy valve pipe and fittings to attenuate sound and vibration (See API Medical Research Report EA 7301). Cryogenic System: Cryogenic system is the name of piping system, which handles fluids at very low temperature in a process requiring manufacture of Oxygen, Nitrogen, Argon; Methane purification piping, low temperature gas treatment, i.e. Nitrogen wash unit-piping at a temperature level at – 400F to absolute zero, i.e. – 459.70F. The cryogenic system or process is nothing but utilization of low temperatures to produce a physical change in liquid, solid or gas to manufacture Oxygen, Nitrogen, Helium, and Methane and to manufacture certain metal superconductors. The main problem in a
cryogenic system is the leakage of heat from the surrounding atmosphere leads to vaporize the cryogenic liquid, which have, generally, very low boiling points and very small latent heat of vaporization. The basic principle to design a cryogenic system is to take care of these special properties of the cryogenic products. The following main and special considerations have to be taken into account: 1. To maintain the slope of the piping upward in the direction of flow to take advantage of the principle of airlift. 2. Maintain the piping in one line, avoiding peak or air pockets, to avoid gas traps. Minimize the heat loss to a minimum for proper operation. The valve should have extended bonnets the stem should be stainless steel to bring the stem seals and the valve handles outside the insulation of the valve. Provide wood, a low thermal conductive material, between the supports’ outside surface and the supports’ resting structure. 3.10 PIPING FLEXIBILITY AND PIPING SUPPORT -DESIGN All piping shall be adequately supported, guided, or anchored so as to prevent undue vibration, deflection or loads on connected equipment & piping and leakage at joints. Piping at valves and equipment such as heat exchangers and pumps, requiring periodic maintenance, shall be supported in such a way so that the valves and equipment can be removed with a minimum necessity of installing temporary pipe supports. If the temperature of the fluid and pipe is between - 29 C to 65 C, it is considered a normal working condition and hence design of flexibility and support is not critical. But if the temperature is above 65 C and higher, the design of flexibility and supports becomes more critical with the rise of temperature. More is temperature; most typical and critical design of supports shall be done based on Piping Flexibility calculation. Careful design of piping support systems of above grade piping systems is necessary to prevent failures. The design, selection, and installation of supports follow the Manufacturers Standardization Society of the Valve and Fitting Industry, Inc. (MSS) standards SP-58, SP-69, and SP-89, respectively. The objective of the design of support systems for process piping systems is to prevent sagging and damage to pipe and fittings. The design of the support systems includes selection of support type and proper location and spacing of supports. Support selection and spacing can be affected by seismic zone. The locations of piping supports are dependent upon four factors, such as pipe size, piping configuration, locations of valves and fittings, and the structure available for support. Individual piping materials have independent considerations for span and placement of supports. Pipe size relates to the maximum allowable span between pipe supports. Span is a function of the weight that the supports must carry. As pipe size increases, the weight of the pipe also increases. The amount of fluid, which the pipe can carry, increases as well, thereby increasing the weight per unit length of pipe. But at the same time, the resistance against deflection in pipe and stresses also increases with increase of the size/ diameter and thickness of pipe. The configuration of the piping system affects the location of pipe supports. Where practical, a support should be located adjacent to directional changes of piping. Otherwise, common practice is to design the length of piping between supports equal to, or less than the specified in the spacing table.
4.7
Piping Flexibility Analysis
Piping flexibility concept: A piping system undergoes dimensional changes, i.e. Expansion or Contraction with any change in temperature. It is constrained from free expansion or contraction by rigid equipment, guides, or anchors connected to it. It will be displaced from its unrestrained position. This is called thermal displacement. Total displacement strains due to thermal displacement, reaction displacements and externally imposed displacements, cumulative effect on piping system shall be considered together in determining the total displacement strains in various parts of the piping system taken together. But when the layout of piping system is designed wrongly, stresses cannot be considered proportional to the displacement strains throughout piping system. Then excessive amount of stress may occur in localized portions of the system. Operation of unbalanced system in the creep range may aggravate the deleterious effects due to creep strain accumulation in the most susceptible regions of the system. When the layout of piping system is designed properly, the displacement strain in piping system at any point are well distributed within the permissible range and hence stresses can be considered proportionally distributed over the total system and within the acceptable limit by selective use of Cold Spring. Where the piping lacks built in changes of direction or where it is unbalanced, large reactions or detrimental overstrain can be developed. All bending strains, tortional strains, reactions or detrimental overstrains can be brought within prescribed limit and flexibility of piping system can be improved by providing one or more of the followings means: 1) More bends, 2) more loops 3) offsets 4) swivel joints 5) corrugated pipe 6) expansion joints of bellow types or slip-joint types or other suitable devices. This permit angular, rotational or axial movement, suitable anchors ties should be provided if necessary to resist end forces produced by fluid pressure restriction resistance to movement. Flexibility analysis not required: For the following piping system the flexibility analysis is not required. Flexibility analysis required: Any piping system, which does not satisfy the above three criteria, shall be analysed for flexibility by any one of (a) simplified (b) approximate or (c) comprehensive method. (I.e., by analytical and chart methods which provide an evaluation of the forces, moments and stresses caused by displacement strains as per requirement of the code. Flexibility and stress intensification factors: In absence of directly available data, the flexibility factors “K” and the stress intensification factors “I”, as given in appendix D of ANSI B 31.3, shall be used.
STRESS ANALYSIS R EQUIREMENTS : Further, piping systems may be subjected to many diversified loading and stresses. Generally, stresses are caused by 1) Pressure, 2) Weight of pipe, fittings, and fluid, 3) external loading, and 4) thermal expansion. They are significant in the stress analysis of a piping system. Normally, most pipe movement will be due to thermal expansions. A stress analysis should be made for a two anchors (fixed points) system if the following criterion is not satisfied: D
1
Where: D = nominal pipe size, inches;
1=
expansion to be absorbed by pipe, inches; U = anchor distance, feet (straight-line distance between anchors); L = actual length of pipe, feet; S = allowable stress, psi;
30S (L – U) 2 Em
Em = modulus of elasticity of the piping material in the cold condition, psi (Em=30 x 106 for Grade B pipe at 700F); 1 = may be calculated by the following equation from ANSI B31.3. 1
LB
= T
12
1
= expansion to be absorbed by pipe, inches;
L = actual length of pipe, feet; B = mean coefficient of thermal expansion at Operating temperatures normally encountered (Approximately 7.0 x 10 –6 inches/inch/0F for carbon steel pipe; T = temperature change, 0F. The following guidelines help in screening piping or systems that generally will not require stress analysis: Systems where the maximum temperature changes will not exceed 500F. Piping where the maximum temperature change will not exceed 750F, Provided that the distance between turns in the piping exceeds 12 nominal pipe diameters. ANSI B31.3 –1973 does not require a formal stress analysis in systems which meet one of the following criteria: The systems are duplicates of successfully operating installations or replacements of systems with a satisfactory service record. The systems can be judged adequate by comparison with previously analysed systems. Minimum Flexibility Requirements: If pipe is made of carbon steel or low alloy steel, it will expand with a rate of 3/4"-1" for each l000 F temperature rise. This means the pipe running between two equipment 100 ft. apart may well expand by 3 to 4 or more inches as it heats up,- but as ends are not free to-move, this increase in length can only be accommodated by straining the pipe. This straining produces a stress in pipe. However, when the pipe is taken out of service, it cools down to ambient temperature, the expansion returns to zero and hence the stress. Every time that the pipe is put into or taken out of service, the same cycle of event occurs. The pipe starts from stress free condition when cold and has stresses imposed which reach a maximum at operating condition and reduce to zero when the pipe is taken out of service. The type of straining described, if repeated often enough will cause the pipe to crack. The cracking will start at a point or points where the stresses are maximum. This is called “fatigue failure”. The various codes and standards covering the design of piping system puts a limit to maximum stresses which the system can be subjected when put to use. This limit is called the “allowable stress range for expansion” and generally denoted by SA. Analysis of Metallic Piping: No formal analysis of adequate flexibility is required for a piping system if; (a) it duplicates or replaces without significant change, a system with a successful service record, (b) it can be readily judged adequate by comparison with previously analyzed system, and (c) it is of uniform size, has no more than two point of fixation, no intermediate restrains and falls within limitation set by the equation.
Code Requirements: ASME and ANSI codes contain the reference data, formulae, and acceptability limits required for the stress analysis of different pressure piping systems and services. ASME B31.3 requires the analysis of three stress limits, such as, Stresses due to sustained loads, Stresses due to displacement strains, and Stresses due to occasional loads. Although not addressed by code, another effect resulting from stresses that is fatigue is examined. The layout of piping often provides inherent flexibility through change in direction of the piping route and hence bending and torsion stress produced in the piping system are within the prescribed limits. The amounts of axial tension or compression strain, which produce large reaction, are usually small. Allowable stresses: The allowable displacement stress range, permissible additive stress and the stress intensification factors as per the requirement of codes. Modulus of elasticity: Modules of elasticity (E) shall be used to calculate the flexible analysis. Poison’s Ratio: Poison’s ratio may be taken as 0.3 at all temperature for all metals. Purpose of Stress Analysis: Flexibility Analysis of Piping is done to determine the amount of stresses governing flexibility in the layout and to establish that the required flexibility has been provided in layout. there are number of criteria defining the minimum acceptable flexibility and these fall into two main categories: i) Maximum allowable stress range in the pipe and ii) The limiting values of forces and moments which piping is permitted to impose on connected equipment. The flexibility required in those cases where the piping reaction on connected equipment governs, invariably overrides that required to satisfy the maximum stress range condition. After piping materials, design pressure and sizes have been selected; a stress analysis is performed that relates the selected piping system to the piping layout and piping supports. The analysis ensures that the piping system meets intended service and loading condition requirements while optimizing the layout and support design. The analysis may result in successive reiterations until a balance is struck between stresses and layout efficiency, stresses and support locations and types. The stress analysis can be a simplified analysis or a computerized analysis depending upon system complexity and the design code. Stresses due to Sustained Loads: The stress analysis for sustained loads includes internal pressure stresses, external pressure stresses, and longitudinal stresses. ASME B31.3 considers stresses due to internal and external pressures to be safe if the wall thickness meets the pressure integrity requirements. The sum of the longitudinal stresses in the piping system that result from pressure, weight and any other sustained loads should not exceed the basic allowable stress at the maximum metal temperature. The new piping system replaces in kind, or without significant change, a system with a successful service record. The new piping system can be readily judged adequate by comparison to previously analyzed systems; and The new piping system is of uniform size, has 2 or less fixed points, has no intermediate restraints, and meets the following empirical condition: Stress due to Thermal expansion: For calculation of the value of stress range or the value of reactions on supports and connected equipment, the value of thermal displacement is used. Internal Pressure/External Pressure Stress: The stresses due to internal pressure are considered safe when the thickness including reinforcement is adequate (using the value SH’ the allowable stress at the operating temperature). Longitudinal Stresses (SL): The sum of longitudinal stresses due to pressure, weight and other sustained loading shall not exceed the basic allowable stress (SH). Pipe thickness for calculation of SL must be reduced by allowance such as corrosion, erosions, manufacturing tolerance and grove depth. (1.33 times in case of occasional loads such as wind/earth quake)
Allowable displacement stress = SA = f (1. 25 Sc + O. 25 Sf); Where, Sc - Basic allowable stress at min. temp. SH - Basic allowable stress at max. temp. Sf - Stress range reduction factor for cyclic condition for total number of full temperature cycles over expected life Stress range reduction factor: When SW-is greater than the calculated value of SL’ the difference between them is added to the term 0.25 SH in the above equation. In that case, the revised formula becomes; S = f [1.25 (Sc + SM ) - SL]. Cold Spring: Cold Spring is the intentional deformation or pulling of the piping during assembly to produce a desired initial displacement and stress. Cold Springs is beneficial in the sense that it serves to balance or reduce the magnitude of stress under initial and extreme displacement conditions. The service life of piping system is more affected by the range of stress variation than by the magnitude of the stress. Piping Components (Auxiliaries): Those elements other than straight pipe which go to make up a complete piping system are described as “Piping Components”. These are important to know to the extent of knowing their individual effects on the flexibility of piping system and the stresses in it, before going for a analysis of complicated piping system. The common auxiliaries used are bends, tees, reducer flanges. The deflection of a beam when it is subjected to bending and torsion is shown in figure. If the same length of pipe is subjected to torsion, the rotation of one end relative to other is given by,
TL θ = ------GJ
Where, θ - Angle of twist in radians; T Torsion moment, lb/inch; L - Length in inch; G Modulus of rigidity, Ib/ inch 2; J - polar moment of inertia, inch 4
This result is very important considering 3-D layouts. It shows that a given length of pipe will give 30% more rotation if moment from adjacent leg produces torsion instead of bending. Torsion deflection alone is rare as means of obtaining flexibility, but the fact demonstrated above may influence the stress engineer in choice of alternative routes for a pipe. Elbows: These are used when change in direction of pipe is required, .they can be of the type short radius, long radius, or pipe bends. The analysis of piping systems considers bending of elbows for the maximum bending stress. The analysis of the pipe bends when subject to a bending moment shows that when curved pipe is subjected to a bending moment in its own plane, the circular cross section undergoes changes and is flattened and this results in increased flexibility. The ratio of the flexibility of a bend to that of a straight pipe having the same length and cross section is known as “flexibility factor” and usually denoted by letter "K". Now let us examine how this flattening of elbow or change in cross section occurs. Let us consider an elbow with a neutral axis is subjected to a bending moment. The outer fibre of elbows will be subjected to tensile stress and the inside surface to a compressive stress. Let us take a thin cross section and study in detail. The resultant tensile load on outer fibre results in inward radial load in the element. Similarly, the compressive load on inside fibre also produces a resultant inward radial load on the element. If we now take a slice as a cross section of pipe and draw the loading diagram
for the ring which is in effect. Under the loading, the ring flattens into an ellipse with its major axis horizontal. If we now reverse the sign of bending moment the cross section will elongate instead of flattening. If we now consider the element in more detail, we see that the flattening produces bending moments in the ring which are maximum at the end of the horizontal diameter. These moments produce a stress which varies from tension to compression through the thickness of pipe wall and is circumferential in direction. If we consider the half of the ring, the circumferential stress in pipe wall due to moment can be many times the value calculated as (My/I) as per ordinary bending theory for structural members. The factor by which the circumferential stresses exceed the longitudinal stresses in bend is called the “Stress intensification factor” often denoted as S.l.F. One of the practical manifestations of the existence of these circumferential stresses is that when an elbow is subjected to repeat in-plane bending, it ultimately develops a fatigue crack along its sides. When we take into account the elbows of a piping system, we are therefore able to claim additional flexibility due to this flattening, but at the same time we must also take into account the induced circumferential stresses by multiplying the stresses at the bends due to overall bending moment in the piping system by appropriate “stress intensification factor”. The expression for calculating both factor and stress intensification factor are given in codes such as B 3l.3 and are as followed. Branch Connections: The resultant bending stress requires a bit more attention as the section modulus Z for header and branch is slightly different. The pipe wall thickness has no significant effect on bending stress due to thermal expansion but it affects the end reactions in direct ratio. So overstress cannot be remedied by adding thickness; on the-contrary, this tends to make matter worse by increasing the end reactions. Effect of Pressure on Stress Intensification Factor and Flexibility Factor: Some of the piping codes give formulas for correcting the values of SIF and flexibility factor for elbows and bends. When the pressure effects are considered, SIF values are lower thus actually reducing the value of thermal stress. However, the terminal forces increase because of reduced flexibility at elbows. Pressure can affect significantly the magnitude of flexibility factor and SIF in case of large diameter and thin wall elbows. The correction factor CKF for flexibility factor due to pressure on elbows is considered. b. Stresses due to Displacement Strains: Constraint of piping displacements resulting from thermal expansion, seismic activities or piping support and terminal movements cause local stress conditions. These localized conditions can cause failure of piping or supports from fatigue or over-stress, leakage at joints or distortions. To ensure that piping systems have sufficient flexibility to prevent these failures, ASME B31.3 requires that the displacement stress range does not exceed the allowable displacement stress range. c. Stresses due to Occasional Loads: The sum of the longitudinal stresses due to both sustained and occasional loads does not exceed 1.33 times the basic allowable stress at maximum material temperature. d. Fatigue: Fatigue resistance is the ability to resist crack initiation and expansion under repeated cyclic loading. A material’s fatigue resistance at an applied load is dependent upon many variables including strength, ductility, surface finish, product form, residual stress, and grain orientation. Piping systems are normally subject to low cycle fatigue, where applied loading cycles rarely exceed 105. Failure from low cycle fatigue is prevented in design by ensuring that the predicted number of load cycles for system life is less than the number allowed on a fatigue curve, or S-N curve, which correlates applied stress with cycles to failure for a material. Because piping systems are generally subject to varying operating conditions that may subject the piping to stresses that have significantly
different magnitudes, the following method can be used to combine the varying fatigue effects. e. Support Spans Spacing is a function of the size of the pipe, the fluid conveyed by piping system, the temperature of the fluid, and the ambient temperature of the surrounding area. Determination of maximum allowable spacing, or span between supports, is based on the maximum amount that the pipeline may deflect due to load. Specific metallic piping materials have particular requirements for the design of piping supports. Concentrated loads, such as valves, meters, and other fittings, should be independently supported. As a thumb rule, spans for insulated lines should be reduced by approximately 30% from those for un-insulated pipes. Calculations should be performed for each application since material strength varies by temper and manufacturing method. Following Table summarizes support spacing for carbon, stainless steel, nickel 200, and nickel 201 pipes. Support of nickel pipe should follow similar principles of other metallic piping systems. Nickel 200 is pure wrought nickel. Nickel 201 is a lowcarbon alloy of nickel 200, for higher temperature applications. When designing aluminium pipe system supports, either aluminium or padded pipe supports should be specified. Aluminium will corrode when exposed to other metals. Contact with metals such as copper, brass, nickel, and carbon steel should be avoided. The support spacing for aluminium alloy 6063 pipes is also given in Table below. Typically, a deflection of 2.5 mm (0.1 in) is allowed, provided that the maximum pipe stress is limited to 10.3 MPa (1,500 psi) or allowable design stress divided by a safety factor of 4, whichever is less. Code Requirements: - Sets forth the engineering requirements deemed necessary for safe design and construction of pressure piping. - Safety is the main consideration - The above alone will not govern the final specification for any piping installation. - Code is not a designs hand book. - It does not do away with the need of designer or competent engineering judgment.
Design Pressure: Design Pressure shall not be less than the pressure at most severe condition of coincident internal / External and temperature min / max expected during service. Design Temperature: Design Temperature shall be the coincident temperature at severe condition, such as, Fluid temp; ambient temp; and Heating or Cooling medium. Internally Insulated Piping: To be determined by heat transfer calculation limitation of calculated stresses due to sustained load and displacement strains, such as, (a) Internal pressure stresses; mill tolerance 12.5% ; Min. thickness = T – mill tolerance > t + C, where C - Sum of mechanical allowance (thread) + corrosion allowance and t- Pressure design thickness. P = Internal design pressure gage. D =
Outside diameter. S = Stress value for material from table A-1. E = Quality factor table A-1A / A-1B, Seamless Pipe, E = 1.0; E R W Pipe, E = 0.85; Furness butt welded Pipe, E = 0.6; Electric fusion welded Pipe, E = 0.95; Double Butt Welded and 100% radio graphed Pipe, E = 1.0. Y - Coefficient from table 304.1.1 t < D/6, t ≥ D / 6 d – inside diameter (max.); Function of material and design temperature 0.4 to 0.7. Branch Reinforcement: t = 2.5 x (Thickness of pipe – Mill tolerance – Corrosion Allowance) for header or 2.5 x (Thickness of pipe – Mill tolerance – Corrosion Allowance) for branch + Tr. The term W, weight per length, is the uniformly distributed total weight of the piping system, and includes the weight of the pipe, the contained fluid, insulation, and jacket, if appropriate. Due to the many types of insulation, the weight must be calculated after the type of insulation is selected; see Chapter 11 for insulation design. Pipe Bends: The thickness required is at the mid-span at side wall on bend centre line I = 1.0. Mitre Bends: Angular offset more than 3 deg are required to be checked.
Table: Beam Coefficient (m) Beam Coefficient (m ) Beam Characteristic 76.8 Simple, single span 185.2 Continuous, 2-span 144.9 Continuous, 3-span 153.8 Continuous, 4 or more span Note: These values assume a beam with free ends and uniform loads. For piping systems with a fixed support, cantilever beam coefficients may be more appropriate. Source: Manual of Steel Construction, Spacing of Supports: Proper spacing of supports is essential to the structural integrity of the piping
system. An improperly spaced support system will allow excessive deflection in the line. This can cause structural failure of the piping system, typically at joints and fittings. Excessive stress can also allow for corrosion of the pipe material by inducing stress on the pipe and, thereby, weakening its resistance to corrosive fluids. The amount of sag, or deflection in a span, is calculated from the following equation: Where: y = deflection, mm (in); W = weight per length, N/mm (lb/in); l = span, m (ft); n = conversion factor, 10-3 m/mm (1 ft/12 in); m = = beam coefficient, E = modulus of elasticity of mE I pipe material, MPa (psi); I = moment of inertia, mm4 (in4). Improper spacing of supports can allow fluids to collect in the sag of the pipe. Supports should be spaced and mounted so that piping will drain properly. The elevation of the down-slope pipe support should be lower than the elevation of the lowest point of the sag in the pipe. This is determined by calculating the amount of sag and geometrically determining the difference in height required. W (l/n) 4 y
(l/n) 2 y h= 0.25 (l/n) 2y2
Where: h = difference in elevation of span ends, mm, (in); l = span, m (ft); n = conversion factor, 10-3 m/mm (1 ft/12 in); y = deflection, mm (in).
Piping system shall be designed in such a way giving sufficient loops in the total runway of pipe to have sufficient flexibility to prevent thermal expansion or contraction effect, movement or displacement of piping supports effect and pull or thrust effect on the nozzle of the equipment. If the piping is not efficiently designed flexible, it will get damaged due to the following effects: The piping or supports fail due to overstressing or fatigue. Leak at joint occurs due to pulling or pushing while expansion or contraction. Distortion in piping and valve or in connected equipment such as pumps, compressors, or turbine due to overstressing in pipe resulting from excessive thrusts and movement in piping. The flexibility in piping system should meet the following requirement minimum to confirm the flexibility. (1) The computed stress range at any point due to displacement in the piping system should not exceed the allowable stress range. SA =
f (1.25 Sc + 0.25 Sh)
--------------------- (1)
Where, Sh > Sl, then the difference, i.e. (Sh – Sl) must be added to the term 0.25 Sh above. In that case it will be as mentioned below: SA = f {1.25 Sc + 0.25 Sh + (Sh – Sl)} ----------------- (2) = f {1.25 (Sc + Sh) - Sl} Where, Sc = Basic allowable stress at minimum metal temperature expected during the
displacement cycle under analysis. Sh = Basic allowable stress at maximum metal temperature expected during the displacement cycle under analysis. F = Stress range reduction factor from the table given here or calculated by equation on given below. f = 6.0 (N) –0.2
1.0
----------------- (3)
Where, N = Equivalent number of full displacement cycles during the expected service life of the piping system i.e. reaction forces computed as per equation given below should not be detrimental to supports or connected equipment. R (1 – 2C) Em Rm = 3 Ea
Where, Rm = Estimated instantaneous maximum reaction force or moment for a two anchor Piping system without intermediate restraints and
C = Cold spring factor varying from zero (for no cold spring) to 1.0 (for 100% cold spring). Ea = Modulus of elasticity at installation temperature. Em = Modulus of Elasticity at maximum or minimum metal temperature. R = Range of reaction forces or moments derived from flexibility analysis corresponding to the full displacement stress range and based on Ea. The computed moment of piping should be within the limit and shall be properly accounted for in the flexibility calculation.
4.8
Pipe Supports-Design
The supports are required for supporting all concurrently acting loads due to weight effects such as the weight of the piping, valves, fittings, insulating materials, suspended hanger components and all appurtenances along with the weight of normal operating contents, loads introduced by service pressure and temperatures, vibrations, wind, earthquake shock, the added weight of water used for hydrostatic testing and displacement strain. Calculating Pipes Weight: This is a weight calculating formula for steel pipes. If the outside diameter and the wall thickness of a steel pipe are known, the weight per foot can be expressed as: m = 10.68 (do - tw) tw
-------------------------------- (1)
Where, m = weight per foot (lbs/ft), do = outside diameter (inches), tw = wall thickness (inches. Example: Weight of 4" Schedule 40 Steel Pipes. The outside diameter (do) of 4" Schedule 40 Steel Pipe is 4.500 inches. The wall thickness is 0.237 inches. The weight per foot can be calculated using (1) as: m = 10.68 ((4.500 in) - (0.237 in)) (0.237 in) = 10.79 lbs/ft. Purpose of pipe supports: The main purposes of layout and design of piping and support is to prevent the followings: Piping stress in excess of those permitted in the code. Leakage at the joints. Excessive thrust and moments on connected rotating equipment such as pump, turbine or compressors. Excessive stresses in the supporting elements. Resonance with imposed or fluid induced vibrations. Excessive interference with thermal expansion and contraction in piping which is otherwise adequately flexible. Unintentional disengagement of piping from its supports. Excessive piping sag in piping requiring drainage slopes. Excessive distortion or sag of piping (e.g., thermo plastics) subject to creep under conditions of repeated thermal cycling. Excessive heat flow, exposing supporting elements to temperature extremes outside their design limit. In general, the pipe supports location and design is done based an simple calculation and engineering judgment. However, when a more refined design is required then the stresses, moments and reactions determined during the piping flexibility analysis, are used in design of the piping supporting elements. However, most of the supporting components are designed and standardized based on diameter, temperature (hot or cold) and insulation required. Accordingly standard sketches of various types of supports are given in MSS-SP-58 and SP-69. For special condition and high temperature line all supports locations and supporting elements are design considering all the above factors after piping flexibility and stress analysis. Support Types: There are various types of supports used in piping system. These should be as
simple as conditions allow. Stock items are used wherever possible, especially for piping held from above. To support piping from below, supports are usually made to suit from plates, pipes and pieces of structural steel. Following hardware is used to create supports. However following supports are mainly used in piping system. The type of support selected is equally important to the design of the piping system. The stresses and movements transmitted to the pipe factor in this selection. Pipe supports should not damage the pipe material or impart other stresses on the pipe system. The expected movement at each support location dictates the basic type of support. The initial support design must address the load impact on each support. Typically, a moment-stress calculation is used for 2-dimensional piping, and a simple beam analysis is used for a straight piperun. If a pipe needs to have freedom of axial movement due to thermal expansion and contraction or other axial movement, a roller type support is selected. If minor axial and transverse (and minimal vertical) movements are expected, a hanger allowing the pipe to ‘swing’ is selected. If vertical movement is required, supports with springs or hydraulic dampers are required. Other structural requirements and conditions that have the potential to affect piping systems and piping support systems are analyzed. Pipes that connect to heavy tanks or pass under footings are protected from differential settlement by flexible couplings. Similarly, piping attached to vibrating or rotating equipment is also attached with flexible couplings. Rest Support: The weight of the piping is usually carried on supports made from structural steel, or steel and concrete. Hanger Support: It is a device, which suspends piping (usually a single line) from structural steel, concrete or wood. These are generally adjustable for height. The simple rod type hanger support, suspended from top, or base, bracket, structural members are used where there is no movement or negligible vertical and horizontal movement in the pipe. The simple rod type hanger support, suspended from top, or base, bracket, structural members is permitted for used, even, where there is zero vertical movement and limited or definite horizontal movement in the pipe, i.e. up to 4 degree deflection in the overall length of vertical hanger rods. Hanger support includes pipe and beam clamps, clips, brackets, rods, straps, chains, and other devices. They shall be proportioned to all required loads to be hanged. The hanger support should not be provided at the centre of gravity of the pipe because the hanger would then act as a pivot point and would not resist the sway. The hanger support should also not be provided below the centre of gravity of the pipe because the unstable turnover condition would result in the piping system. The hanger support should be provided, most desirably, above the centre of gravity of the pipe
Figure: Flexibility Arrangements (Source: SAIC)
Anchor Support: A rigid support that prevents transmission of movement (thermal, vibratory etc.) along piping. Construction may be from steel plate, brackets, flanges, rods, etc. Attachment of anchors to pipe should preferably encircle the pipe and be welded all around as this gives better distribution of stress in the pipe wall. Anchor type support is used to maintain an essentially fix position of the pipe in all direction. For anchor the pipe in its location, anchors should be designed to withstand the forces and movements as mentioned below: Forces or moments required to compress, extend, offset or rotate the joints. Static fraction of the pipe in moving on its supports between extreme extended and contracted positions. Operating and transient dynamic forces caused by the following medium or fluid. Other piping forces or moments. Pressure thrust of the pipe
The purpose of a main anchor is to divide a pipeline into individual expanding sections. This shall be designed to withstand the full line thrust due to internal pressure plus the force required compressing the expansion joint plus friction load. Anchors at bends such as elbows and centrifugal thrust also shall be added. Anchors on straight pipe containing cap or valve, line thrust due to internal pressure is, Fs = AP Where, Fs = Static thrust; A = Effective area or corrugation; P = Internal line pressure lb/ in2 or kg / cm2. Anchors at pipe bends, such as elbows, etc., the line thrust due to internal pressure is: F = Fc + Fs + F1A Where, F = Total line thrust; Fc = Centrifugal thrust; Fs = Static thrust; FIA = Force required to compress the spring.
V2 = Sin
2 a Y Where, A = Internal Area of pipe; Y = Density of fluid (lb / Ft3 or kg / m3); V = = Angle Fc Velocity (Ft / Sec or M/Sec.); of pipe bend; /2 a
Where, Fs = 2 op Sin
/2; a = Acceleration due to gravity (32.2 Ft/ Sec. 2 or 9.81 M / Sec. 2)
Intermediate Anchor Supports: Intermediate anchor shall be designed to withstand the force necessary to compress the expansion joint to its full rated movement + Friction load.
Tie Support: It is an arrangement of one or more rods, bars etc. to restrain movement of piping. Dummy Leg Support: In this an extension piece (of pipe or rolled steel section) is welded to an elbow in order to support the line. This part rests or anchors on some steel member. Guide: This is a means of allowing a pipe to move along its length, but not sideways. Proper alignment is of vital importance in the installation of all expansion joints. The pipe guides are used to maintain the alignment of the pipeline allowing moving freely in one direction. Guide spacious should be in accordance with the following standard. The first guide must be located within a distance of four pipe diameters from the expansion joint and the second within fourteen pipe diameters from the first guide. Guide support is also one kind of semi-anchor type. It is used to restrict movement of the pipe in transverse (perpendicular direction to the axis of the pipe) and to allow movement of the pipe in axial direction. Guides are used to protect terminal equipment or other weaker portion of the system by the side of the pipe. If control the movement or to allow the expansion into those portions of the system which are designed to absorb them. The guides also facilitate the expansion joint movements occur in the direction on for which the expansion joint is designed.
Shoe: It is a piece of metal attached to the underside of a pipe, which rests on supporting steel. It is primarily used to reduce wear from sliding for lines subject to movement. It permits insulation to be applied to pipe. Saddle: It is a welded attachment for pipe requiring insulation, and subject to longitudinal or rolling movement (resulting from temperature changes other than climatic). Saddles may be used with guides. Sliding Supports: In this two slide plates of graphite, Teflon or some special materials, fixed to steel plates, are fixed to the flat surface of the pipe support. These plates are faced for low friction able to withstand mechanical stress and temperature changes. The sliding supports are provided where the piping is supported from below or at the bottom to facilitate the sliding movement of the pipe during its horizontal movement. Sliding supports (or shoes) are the support where a saddle or a shoe is welded with pipe and the same is resting on bracket. There is a height in the shoes to accommodate insulation thickness. Sliding supports are designed to allow the movement in the pipe in axial direction up to a designed length and a small movement in transverse direction. Constant Load Hanger: This device consists of a coil spring and lever mechanism in housing. Movement of the piping, within limits, will not change the spring force, holding up the piping; thus no additional force will be introduced to the piping system.
Variable Spring Hanger: This device consists of a coil spring in housing. The weight of the piping rests on the spring in compression. The spring permits limited amount of thermal movement. A variable spring hanger holding up a vertical line will reduce its lifting force as the line expands toward it. A variable spring support would increase its lifting force as the line expands towards it. Both place load on piping system, and where this is undesirable, a constant-load hanger can be used instead. Hydraulic Dampener: These are also called as shock snobbier or sway suppressor. One end of the unit is attached to the piping and the other to structural steel or concrete. The unit expands or contracts to absorb slow movement of piping, but is rigid to rapid movement. A hydraulic cylinder type support is used to give a constant supporting force to the pipe. Safety devices and stops are provided in the hydraulic support to support the load in case of hydraulic failure. Non-integral attachment type supports: These types of supports include clamps, U-bolts, cradles, saddles, straps etc., in which the reaction between the piping and the support is by contact. All the above types of supporting elements are used to suitably transmit the load of piping to a foundation or heavy structures made and capable of bearing the load without deleterious effect through supporting structural members like bracket etc. Sway Brace: This is also called as sway arrestor. It is essentially a helical spring in a housing that is fitted between piping and a rigid structure. Its function is to buffer vibration and sway. Spring supports: Where there is the vertical movement in the pipe, the spring support should be incorporated with spring cushions. Spring supports are designed to extent a supporting force at a point of attachment to the pipe equal to the load as determined by the weight balance calculations. They are provided with means to prevent misalignment, buckling or eccentric loading of the springs and to prevent unintentional disengagement of the load. Constant spring hangers provide a substantially uniform supporting force throughout the range of travel. The use of this type of spring hanger is advantageous at locations subjected to appreciably movement with thermal changes. The type of hanger spring supports should be selected so that their travel range exceeds expected movement of the pipe. All spring support shall be provided with a lock of prevent the overstressing the spring hangers due to excessive deflections and also with a position indicator to indicate the total travel of the springs. There are two types of spring supports, commonly used n piping: (1) the coiledspring vibration dampener support and (2) the hydraulic vibration dampener support, which operates by means of a controlled flow of fluid through an orifice and whose resistance to the movement of the pipe increases with the speed of the displacement of the pipe. The distinctive advantage of the hydraulic hanger support is that there is a minimum resistance to the movement of the pipe due to thermal expansion in the pipe. Further, there are two types of the coiled-vibration dampener support: (a) the opposed-spring type and (b) the double acting spring support. Roller support: Where there is an assured movement in the pipe along the axis and in the transverse direction, a roller support can be used at the bottom of the pipe to provide the movement of the pipe in both directions. Counter weight supports: Counter weight support is made of chains, cables hangers, rocker arms and other devices to stop the limit of travel of the pipe as well as to attach the counter weight load to the piping. Nozzle Support: Piping connected to centrifugal pumps or equipments is supported properly to avoid the followings: Stress in the pipe due to pressure, thermal expansion and contraction, weight, and wind loading do not exceed the values, which the pump can safely sustain. Although piping reactions and stresses can
be evaluated accurately and the stress imitation for the pipe is closely defined, the values of acceptable reaction on pumps are not so well defined. The following notes define limits of piping reaction on pump, and describe support procedures that have proved satisfactory in the past.
Fig: Spring Supports Selection of Pipe Support: The selection of support types is dependent upon four criteria: the temperature rating of the system, the mechanism by which the pipe attaches to the support, protective saddles that may be included with the support, and the attachment of the support to the building or other structures. Support types are most commonly classified in accordance with MSS SP-58. Figure 3-2 displays some of the support types applicable to liquid process piping systems. The selection of the appropriate support type is made according to MSS SP-69. Table 3-8 provides guidance for process system temperatures.
Some piping systems utilize protective saddles between the pipe and the support member. This is done to minimize the stress on the pipe from point loads. In addition, pipe insulation requires protection from supports. Saddles support piping without damaging insulation. The method by which the supports attach to buildings or other structures is addressed by the design. Typical pipe supports are in the form of hangers, supporting the pipe from above. These hangers may be attached to a ceiling, beam, or other structural member. Pipelines may be supported from below as well, with pipe stanchions or pipe racks. Pipe supports may be rigidly attached to a structure, or allow for a pivoting axial motion, depending on the requirements of the system. Some piping systems require adjustable pipe supports. One reason for this requirement is the cold spring action. Cold spring is the action whereby a gap is left in the final joint of a piping run to allow for thermal expansion of the pipeline. This action results in the offset of all points along the piping system, including the attachments to pipe supports, and requires that supports be adjustable to accommodate this offset. From a maintenance consideration, cold springing should be avoided if possible through proper thermal expansion and stress analyses. Vertical adjustment is also usually necessary for pipe supports. Settlement, particularly in new construction, may result in an improper deflection of the elevation of a pipe support. To maintain the proper slope in the pipeline, thereby avoiding excessive sag between supports and accumulation of the product being carried by the pipe, the possibility of vertical adjustment is accommodated in the design of pipe supports. Table: Pipe Support- “Support-Span” in Meter Pipe Size INCH ¾ 1 1½ 2 3 4 6 8 10 12 14 16 18 20 24
Gas Line Bare Insulated Pipe Pipe Up to 300 3000C -4000C 4.5 3.5 2.5 5.0 4.0 3.0 6.0 5.0 4.5 6.5 5.0 4.5 8.0 6.5 5.5 9.0 7.5 6.5 11.0 9.5 8.5 12.0 11.0 10.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0
Liquid Line Bare Insulated Pipe Pipe Up to 300 -4000C 3000C 4.0 3.0 2.0 4.5 3.5 3.0 5.0 4.5 3.5 5.5 4.5 3.5 6.5 6.0 5.0 7.5 7.0 6.0 9.0 8.0 7.5 10.0 10.0 9.0 12.0 10.5 10.5 12.0 12.0 11.5 12.0 12.0 11.5 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0
Table: Pipe Support- “Guide Support-Span” in Meter
Pipe Size ¾ 1 1½ 2 3 4 6 8 10 12 14 16 18 20 24
(inch)
Vertical Line 6.0 6.0 6.0 6.0 8.0 8.0 10.0 10.0 12.0 12.0 14.0 14.0 16.0 16.0 16.0
Horizontal Line 12.0 12.0 12.0 12.0 18.0 18.0 24.0 24.0 30.0 30.0 30.0 36.0 36.0 42.0 42.0
Table: Pipe Support- “Support-Span” in Meter Nominal Pipe Size, mm (in) 15 (0.5) 20 (0.75) 25 (1) 40 (1.5) 50 (2)
Maximum Support Spacing, m (ft) SS Sch 5S SS Sch CS Sch 40 SS Sch CS Sch 80 10S 40S 2.9 (9.4) 3.2 (10.3) 3.4 (11.2) 3.8 (12.6) 4.1 (13.4)
2.9 (9.6) 3.2 (10.6) 3.6 (11.9) 4.2 (13.8) 4.5 (14.9)
80 (3)
4.8 (15.7)
5.2 (17.1)
100 (4)
5.0 (16.5)
5.6 (18.3)
150 (6)
5.9 (19.4)
6.3 (20.6)
200 (8)
6.2 (20.2)
6.8 (22.4)
250 (10)
7.1 (23.3)
7.4 (24.1)
300 (12)
7.4 (24.3)
7.8 (25.6)
2.1 (7.0) * 2.1 (7.0) * 2.1 (7.0) * 2.7 (9.0) * 3.0 (10.0) * 3.7 (12.0) * 4.3 (14.0) * 5.2 (17.0) * 5.8 (19.0) * 6.1 (22.0) * 7.0 (23.0) *
2.9 (9.6) 3.3 (10.7) 3.6 (12.0) 4.3 (14.2) 4.8 (15.6)
2.5 (8.3) 2.9 (9.4) 3.2 (10.5) 3.9 (12.7) 4.3 (14.1)
5.8 (18.9)
5.2 (17.1)
6.4 (21.0)
5.8 (19.2)
7.5 (24.6)
7.0 (23.0)
8.3 (27.4)
7.9 (25.8)
9.1 (30.0)
8.7 (28.7)
9.8 (32.2)
9.5 (31.1)
Notes: CS - ERW Carbon Steel ASTM A 53, grade A.; SS - seamless stainless steel ASTM A 312, TP316L. Table: Nickel Pipe Support- “Support-Span” in Meter Nominal Pipe Size, mm (in) 15 (0.5) 20 (0.75) 25 (1) 40 (1.5)
Ni 200, Sch 5
Maximum Support Spacing, m (ft) Ni 201, Ni 200, Ni 201, Ni 200, Sch 5 Sch 10 Sch 10 Sch 40
Ni 201, Sch 40
2.4 (7.8) 2.1 (6.9) 2.4 (7.9) 2.1 (6.9) 2.4 (7.9) 2.1 (6.9) 2.6 (8.6) 2.3 (7.5) 2.7 (8.8) 2.3 (7.7) 2.7 (8.8) 2.4 (7.8) 2.9 (9.4) 2.5 (8.2) 3.0 (9.8) 2.6 (8.6) 3.0 (9.9) 2.6 (8.7) 3.2 2.8 (9.3) 3.5 3.1 3.6 3.1 (10.6) (11.5) (10.1) (11.8) (10.3) 50 (2) 3.4 3.0 (9.9) 3.8 3.3 4.0 3.5 (11.3) (12.5) (10.9) (13.0) (11.4) 80 (3) 4.0 3.5 4.4 3.8 4.8 4.2 (13.2) (11.6) (14.4) (12.6) (15.7) (13.8) 100 (4) 4.3 3.7 4.7 4.1 5.3 4.7 (14.0) (12.3) (15.4) (13.6) (17.5) (15.3) 150 (6) 4.5 4.0 4.8 4.3 5.6 5.0 (14.7) (13.2) (15.6) (14.0) (18.4) (16.4) 200 (8) 4.7 4.2 5.2 4.6 6.3 5.6 (15.4) (13.8) (17.0) (15.2) (20.5) (18.4) 250 (10) 5.4 4.8 5.6 5.0 6.9 6.1 (17.8) (15.9) (18.3) (16.4) (22.5) (20.1) 300 (12) 5.7 5.1 5.9 5.3 7.4 6.6 (18.5) (16.6) (19.4) (17.4) (24.2) (21.6) Notes: Ni 200 = seamless nickel ASTM B 161, alloy N02200, annealed. Ni 201 = seamless nickel ASTM B 161, alloy N02201, annealed. Span lengths are based on a piping system that is a simple single span. Pipe run is not insulated, has a full flow condition that is essentially water and is subject to a maximum operating condition of 93 C (200 F).
Fig: Supports Location Piping Drawing
Figure: Pipe Supports for Ambient Applications (Source: MSS-SP-69. Pipe Hangers and Supports)
Table: Aluminium Pipe Support- “Support-Span” in Meter Nominal Maximum Support Spacing, m (ft) Pipe Size, mm Al 6063, Al 6063, Al 6063, Al 6063, (in) Sch 5 Sch 10 Sch 40 Sch 80 15 (0.5)
2.3 (7.6)
2.4 (8.0)
2.5 (8.3)
2.6 (8.5)
20 (0.75) 2.5 (8.1) 2.6 (8.6) 25 (1) 2.6 (8.5) 3.0 (9.7) 40 (1.5) 2.7 (9.0) 3.2 (10.6) 50 (2) 2.8 (9.3) 3.4 (11.1) 80 (3) 3.2 (10.7) 3.7 (12.2) 100 (4) 3.3 (10.9) 3.9 (12.6) 150 (6) 3.8 (12.6) 4.2 (13.8) 200 (8) 3.9 (12.9) 4.5 (14.7) 250 (10) 4.5 (14.8) 4.8 (15.6) 300 (12) 4.7 (15.4) 5.0 (16.4) Notes: Al 6063 = seamless aluminium ASTM B welded joints.
2.8 (9.1) 3.1 (10.1) 3.6 (11.4) 3.7 (12.3) 4.5 (14.7) 4.9 (16.0) 5.5 (18.1) 6.0 (19.8) 6.5 (21.4) 6.9 (22.7)
2.9 (9.4) 3.2 (10.5) 3.7 (12.2) 4.0 (13.3) 4.8 (15.9) 5.3 (17.5) 6.3 (20.5) 6.9 (22.7) 7.6 (25.0) 8.2 (27.1)
241 A96063, type T6 with
Piping Reaction at Pump: Pumps with vertical nozzles are capable of withstanding a limited amount of Vertical weight load. However, rod hangers shall be located on all suction and discharge lines above or close to vertical nozzles in order to: Reduce overturning moments on pumps due to dead weight. Facilitate the thermal unloading required to correct unavoidable fabrication errors. General Note on Support: Temporary Supports shall be provided before Hydrostatic Testing for bare vapour line. Pipe support saddle material & wall Thickness shall be same of pipe & size of 900 in width x 300 long at point of support bearing surface. The basic span is based on the corrosion allowance, such as, for line up to 1 ½” = 0.05” and for line above 2” = 0.1”. The Guide Spacing is indicative only. Line 10” and above need not be provided with Guide unless required by Stress group. Support locations are independent of pipe size, piping configuration, location of heavy valves and fittings, and the structure, which is available in the plant in the piping. These support spacing may vary to suit the column spacing. The above spacing is for straight run of pipe and does not include the guides, which are required for control of thermal expansion or movements of pipe. The following span between the pipe supports are based on a combined bending stress and the shear stress of 1500 psi when the pipe filled with water and the allowed deflection of pipe between the supports amounting to the max. 2.55 mm. Wherever, there are concentrated weights such as valves or heavy fittings or where there is change in direction of piping system, this support span is not applicable Wherever there is change in the direction of the piping, it is advisable to keep the total length of the pipe between the supports less than 3/4th of the full spans as given in the table. It is also advisable to provide a hanger support at the location immediately adjacent to any change in direction of piping. The piping systems have been classified into the following three temperature conditions in order to provide the criteria for selection of the supports such as hangers, anchors or the other type of supports: a) Hot Temperature Conditions: The temperature ranging from 1200F to and above, such as lowpressure steam, hot water, and hot process piping; boiler plant piping, and high-pressure steam piping. Ambient Temperature Conditions: In this condition, the pipe is neither heated nor cold. It is at the
atmospheric temperature condition. Cold Temperature Conditions: The operating temperature 290C and below, such as chilled water piping, brine system piping or the cryogenic system piping. Friction Load: The thermal movement of pipe exerts a horizontal on the supporting member due to frictional resistance. These forces are independent of the line temperature and the amount of movement taking place. The frictional forces are in the order of 0.2 to 0.3 times the dead load at the point of support. Thus the Pipe, 500 feet of 30” diameter X 0.375” wall thickness and full of oil and 2” insulation, will produce a frictional resistance of about 25 tons. Ten Basic Steps of providing Pipe Support: Procedure for the design and selection of pipe supports has been broken into the followings 10 basic steps of providing the pipe supports, 1. Make Isometric piping sketch. 2. Spot preliminary location of hanger on the sketch. 3. Study building steel structure and adjust location of hangers to suit the same. 4. Check for interference 5. Calculate distribution of weight of piping 6. Summarize hanger loading Calculate distribution of vertical expansion to hangers Calculate distribution of equipment vertical movement to hangers 9. Summarize hanger movements 10. Choose hangers loading and movements The two main factors governing selection of pipe hangers are; 1. Changes resulting from thermal expansion, which causes movement of pipe due to increase of length of legs and displacement of equipment connections. 2. Weight to be supported, which depends on pipe, flowing medium, insulation type, and number and type of fittings in line supported.
4.9 Design
Piping Assembling Joints-
While designing the piping system, the pipe joints shall be selected to suit the material & the fluid service with respect to joint tightness, mechanical strength and permissible leakage through the joints, test condition of pressure, temperature and external loading. Piping joints are of the following types: Butt-Welded joint; Socket-welded joint; Fillet-welded joint; Threaded joint: a) With seal welding, b) Without seal welding; Flange joint; Flared Joints: a) Flared tube joint; b) Flare less tube joint; Compression type tube joint; Caulked Joints; Expanded Joints; Packed Joints; Special joints: a) Bell type b) Packed gland type. 1. Welded Joints: Piping components are welded together with each other end to end with the bevelling at the end to make a V-groove for welding. Backing ring shall not be used for butt-welding. Efficiency factor for butt-welded joint is considered as noted below: Without Radiography, Ej= 0.80 With spot Radiography, Ej= 0.90 With 100% Radiography, Ej= 1.00 Bevelling of Butt-Welded Joint Standards:
Socket welds: In case of socket weld, one part is put into other machined part and then it is welded at the junction point (meeting with each other) outside as shown in figure below. Socket joints shall be avoided as much as possible as it propagates Crevice corrosion and severe erosion. However, socket welded joints are permitted in pipe size 1 ½ “ below in normal category, category-D and severe cyclic condition category service but not in high pressure category service. Fillet Welds: Fillet welds are used for slip-on flanges piping or on supporting saddle or shoe welding. Use of slip on flange is limited to Normal category of fluid service only. 2) Threaded Joints: Threaded joints are allowed in normal or category-D fluid service condition. Threaded joints may be used under severe cyclic condition for a limited purpose such as Pressure Gauge connection, drain & vent plug or caps or other place with safeguarding. Threaded joints shall be avoided in any service where crevice corrosion, severe erosion or cyclic loading or stress may occur. The thickness or schedule of male in relation to the size the piping components to be threaded for making thread joints shall be strictly as per code requirements. It is always better to have a flanged joint in piping assembly. However, sometimes we use the Threaded joints in assembly of the piping system. Following care should be taken while assembling the Threaded joints: All threads should be tapered and as per ANSI B 2.1. Any compound or lubricant to use on the threaded joint should be suitable for the service conditions
and should not react unfavourably with either the fluid service or the piping material. Any kind of sealing compound should not be applied on the Threaded joint to be seal welded. The seal welding of the Threaded joint should be done full threading. The compound if applied on the threaded joint should be removed and the joint should be cleaned thoroughly before seal welding. All the threaded joints should be completely in a straight line to avoid the leakage through the threaded joint. 3) Flange Joints: The flange joints are made with the help of companion flanges installed on the pipe. Then, a suitable gasket is put in between two flange’s faces. The flanges are tightened with suitable bolts and nuts. Assembly of Flange Joints is inspected thoroughly for the damage of the gasket seating surfaces where gasket is seating. If any damage is found on the flange faces, the flange is rejected and a good flange is selected for installing on the pipe. The gasket should uniformly be compressed in between the flanges. For this, a special care is taken while tightening the flanges. The flange should be tightened uniformly all around. The bolt length should be sufficient long to extend completely through their nuts with minimum two to three threads out of their nuts. All bolts should be equal in length. Gasket should not be more than one in the flange contact faces while assembling the flanged joint. There are mainly four type of flanges used in piping system such as, Weld Neck Flange: It is welded end to end with mating component with a groove weld. Unless otherwise safeguarded, weld neck flange shall be used in severe cyclic conditions and higher ratings. Slip-on Flange: It is double welded by inserting the mating component inside the flange and fillet welded at both ends. The use of slip-on flanges should be avoided where many large temperature cycles are expected. Threaded Flange: The inside threaded surface is tightened on the threaded piping components. Socket Weld Flange: Mating components is inserted into the flange and both are welded together at outside junction point with fillet weld. Socket weld flange may be used in 1 ½ inch and below in severe cyclic condition. In piping assembly, few joints are to be made, necessarily, with flanges for the following reasons: For maintenance of the pipe as and when required. For installation of the valves to control the flow of the fluid passing through the pipe. For installation of the instruments to monitor the total system during operation. Other miscellaneous work. 4) Flared Joints: In piping assembly, there is too much tubing work to connect the different tapings on the pipe to the different instruments for operational control purpose. The tubing materials are generally stainless steel. The union joint connects the tubes with the help of a flare. Special care should be taken in Flared Joint. The sealing surface of the flare joint should be inspected for imperfections before assemble of the joint. Any flare having the imperfections should be rejected. Where the manufacturer have supplied a instruction manual and called for a specific number of turns of the nut, this should be counted from the point at which the nut becomes finger tight. 5) Caulked Joints: Caulked Joints should be installed as per the instruction of the manufacturer and care should be taken to ensure adequate engagement of the joint members 6) Expanded Joints: The Expanded Joints should be installed as per the instruction of the manufacturer and care should be taken to ensure the adequate engagement of the joint members. 7) Packed Joints: The Packed Joint is installed to absorb the thermal expansion in the piping system.
A proper clearance, as specified by the manufacturer, should be provided at the bottom of the socket to allow the movement. The Packed Joint should be installed in accordance with the manufacturer’s instruction and a special care should be taken to ensure the engagement of the joint members.
4.10 Design Engineering and Limitations Materials: Any listed Components made of materials not covered in pressure temperature rating but have the same allowable stress as the rated pipe, should be rated not more than 87.5% of nominal thickness of seamless pipe in respect of schedule weight or pressure class of the fittings less all allowances applied to the pipe (i.e., thread depth & corrosion allowance). Unlisted components but conforming in respect of composition, mechanical properties, method of manufacturing and quality control to a specification or standard of a listed materials may be used subject to pressure design is verified according to code. Components made of cast iron or other non-ductile material shall not be used in pressure piping. Allowable Stress: Allowable Stress should not be more than the yield strength at temperature. The sum of (combined) longitudinal stresses due to pressure, weight and other sustained loading and of the stress produced by occasional loads such as wind or earthquake should not be more than 1.33 times the basic allowable stress given in ANSI B 31.3, Appendix A. For casting, the basic allowable stresses should be multiplied by the casting quality factor (EC). Allowances should be included in the minimum design thickness of piping components for corrosion, erosion and thread depth or groove depth. Pipe Wall Thickness: Thickness of a piping component shall be increased to prevent over stress, damage, collapse or buckling due to super imposed loads from supports, ice formation, backfill or other causes. Bends: The minimum thickness (tm) of the bend, after bending, shall not be less than the pipe thickness. An angular offset of 3 degree or less does not require design consideration as mitre bend. Mitre Bends: The maximum allowable internal pressure in a mitre bend, which angle does not exceeds 22.50, should be less than PM Where, SE (T – C) r2
PM = r2
(T - C) PM = (T – C) + 0.643 tan
SE (T – C) x R1 – 0.5 r2
x r2 (T - C)
R 1 - r2
Where, C = the sum of the allowances and mechanical Allowances. E = Quality factors PM = Maximum allowable internal pressure; r2 = Mean radius of pipe using nominal wall thickness; R1 = Effective radius of mitre bend from the centre of the pipe; S = Basic allowable stress; T = Pipe wall thickness; θ = Angle of mitre cut =Half of angle ( ) of change in direction of mitre
joint. A mitre bend made with groove but weld as per above requirement and having Ej >= 0.90 (i.e. with spot radiography), should be used in category-D fluid service and normal category fluid service. A mitre bend made with groove but weld as per above requirement and having Ej=1.0 (i.e. 100% radiography) may be used in category of severe cyclic conditions. A mitre bend shall not be used in category-M fluid service or category high-pressure fluid service. Fitting confirming to MSS-SP-43 and Proprietary “Type-C” Lap-Joint stub end welding fittings should not be used in severe cyclic conditions fluid service. Creased or corrugated bend shall not be used in severe cyclic condition fluid service and higher ratings. In the mitre joint, the length of pipe shall extend not less than `M` distance from the inside crotch of the end mitre bends where, M = the larger of 2.5 (r2 T) 0..5
or
(R1 - r2) ……………….. (i)
Branch: Fabricated branch connection (by welding the branch pipe on run pipe) may be used in category-D and Normal fluid service conditions but shall not be used in severe cyclic condition service and higher rating. Branch Connection can be used subject to the following conditions: Dn i.e. 100
<
Tn D <= 1 B
I . E.
Dn
The run pipe diameter-to-thickness ratio (Dn / Tn) is less than 100. AND THE BRANCH- TO - RUN PIPE DIAMETER RATIO IS NOT GREATER THAN 1. When run pipe (Dn/Tn) is more than 100 i.e. (Dn/Tn) > 100. The branch diameter-to-run diameter ratio ( Db / Dn ) is less than one-half (1/2)
i.e. (Db / Dn) < When angle (Angle between branch and run pipe is less or equal to 45 degree. The 0.5 axis of the branch pipe must intersect the axis of run pipe. Laps: Fabricated laps or flared laps may be used in category-D and Normal fluid service but shall not be used in severe cyclic conditions service and higher ratings. Blanks: The minimum required thickness of a blank shall be not less than tm,
tm = dg C
Where, dg = inside diameter of 3p + gasket for raised or flat face, or the pitch diameter of the RTJ and fully retained gasket. 16 SE
Flange: Slip-on flange should be avoided where High-Temperature cycles are expected. Weld neck flange shall be used under severe cyclic condition and higher ratings. Slip-on and Socket Welding flanges are not recommended for service below -50 0 F temperature of flanges and subject to thermal cycling Bolts: Bolts having yield strength less that 207 MB (30 KSI) shall not be used for flanged joints, ANSI RATING 300# and above. Carbon steel bolts may be used for metal temperature-29 0 C to 204 0 C inclusive and ANSI Rating 300# and lower. Tapped Holes: Tapped holes for pressure retaining bolting in metallic piping components shall be of sufficient depth that the thread arrangement will be at least seven eight times the nominal thread diameter. Reducers: Concentric reducer shall be used in vertical pipe. Eccentric reducer shall be used with straight face at topside up near pump suction piping connection to avoid air pocket to suction. Eccentric reducer shall be used with straight face at bottom side down at other places in horizontal line to maintain the bottom line elevation same. Welding: Backing rings shall not be used in pressure piping welding. Socket weld joints should be avoided in any service where crevice corrosion or severe erosion may occur. Socket weld larger than 1 ½” shall not be used. Metal to Non-metal Flange Joint: Where metallic flange is bolted to a non-metallic flange, both flanges shall be flat face and with a full faced gasket should be provided between them. Expanded Joints: Expanded joints shall not be used under severe cyclic conditions and higher ratings. In other service, a special precaution shall be taken to prevent separation of the joint. Threaded Joints: Threaded joints can be used for normal fluid service without loading and stresses. It may be used for severe cyclic condition where external moment loading is not subjected such as thermocouple well, pressure gauge connection etc. Threaded joint shall be avoided in any service where crevice corrosion, severe erosion or cyclic loading or thermal expansion, contraction may occur. Piping joints shall be selected based on piping material and the fluid service with consideration of joint tightness/permissible leakage and mechanical strength under expected service condition of pressure, temperature, and external loading. Piping Flexibility: Poisson’s Ratio shall be taken as 0.3 at all temperature for all the metals for calculating piping flexibility. Nominal thickness, outside diameters of pipe and fitting shall be used for flexibility calculation. Valves: Extended bonnet valve are reconnected where a temperature differential between the valve stem packing and the fluid in the piping is to be maintain to avoid packing leakage and external icing or other heat flux problem occurs. Gaskets: Full-face gasket shall be used in flat face flange.
4.11 - Data
Piping Engineering Standards Table: Standard Pipe Dimensions
ISO
ANSI Nominal Pipe Size (in) ½ ¾ 1 1½ 2 3 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 40 42 44 48 52 56
Actual D Nominal Pipe Size (in) (mm) (in)
Actual Do (mm)
(in)
0.840 1.050 1.315 1.900 2.375 3.500 4.500 6.625 8.625 10.75 12.75 14.00 16.00 18.00 20.00 22.00 24.00 26.00 28.00 30.00 32.00 34.00 36.00 40.00 42.00 44.00 48.00 52.00 56.00
20 25 32 50 63 90 110 160 225 280 315 356 407 457 508 559 610 660 711 762 813 864 914 1016 1067 1118 1219 1321 1422
(0.787) (0.984) (1.260) (1.969) (2.480) (3.543) (4.331) (6.299) (8.858) (11.024) (12.402) (14.00) (16.00) (18.00) (20.00) (22.00) (24.02) (25.98) (27.99) (30.00) (32.00) (34.02) (35.98) (40.00) (42.00) (44.00) (48.00) (52.00) (56.00)
15 20 25 40 50 80 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 1000 1050 1100 1200 1300 1400
(0.591) (0.787) (0.984) (1.575) (1.969) (3.150) (3.937) (5.906) (7.874) (9.843) (11.81) (13.78) (15.75) (17.72) (19.69) (21.65) (23.62) (25.59) (27.56) (29.53) (31.50) (33.46) (35.43) (39.37) (41.34) (43.31) (47.24) (51.18) (55.12)
60
60.00
1500
(59.06)
1524
(60.00)
EQUIVALENT LENGTH OF 100 PERCENT OPENING VALVES AND FITTINGS IN FEET (API RP 14E) Swing Plug Globe Check Valve 90º Short 90º Long Valve 45º Elbow Branch of Tee Nominal Valve / Radius Elbow Radius Elbow Or Pipe Angle Gate Ball Size Valve Valve Type (Inches) Or Check Ball WeldedThreadedWeldedThreadedWeldedThreadedWeldedThread Valve Valve 1.5 55 26 13 1 1 2 3 5 2 3 8 9 2 70 33 17 2 2 3 4 5 3 4 10 11 2.5 80 40 20 2 2 -5 -3 -12 -3 100 50 25 2 2 -6 -4 -14 -4 130 65 32 3 3 -7 -5 -19 -6 200 100 48 4 4 -11 -8 -28 -8 260 125 64 6 6 -15 -9 -37 -10 330 160 70 7 7 -18 -12 -47 -12 400 190 95 9 9 -22 -14 -55 -14 450 210 105 10 10 -26 -16 -62 -16 500 240 120 11 11 -29 -18 -72 -18 550 280 140 12 12 -33 -20 -82 -20 650 300 155 14 14 -36 -23 -90 -22 688 335 170 15 15 -40 -25 -100 -24 750 370 185 16 16 -44 -27 -110 -- 30 -- - -- -- -- -- -- - -- - 21 -55 40 140 - 36 -- - -- -- -- -- -- - -- - 25 -66 47 170 - 42 -- - -- -- -- -- -- - -- - 30 -77 55 200 - 48 -- - -- -- -- -- -- - -- - 35 -88 65 220
EQUIVALENT LENGTH OF 100 PERCENT OPENING VALVES AND FITTINGS IN FEET (API RP 14E) Enlargement Contraction
Nominal Pipe Size (Inches)
Sudden Reducer
Standard Sudden Reducer Reducer Equivalent length in terms of small diameter
Standard Reducer
d/d=1/4d/d=1/2d/d=3/4d/d=1/2d/d=3/4d/d=1/4d/d=1/2d/d=3/4d/d=1/2d/d=3/4 1.5 5 3 1 4 1 2 7 4 1 5 1 2.5 8 5 2 6 2 3 10 6 2 8 2 4 12 8 3 10 3 6 18 12 4 14 4 8 25 16 5 19 5 10 31 20 7 24 7 12 37 24 8 28 8 14 42 26 9 ----16 47 30 10 --18 53 35 11 --20 60 38 13 --22 65 42 14 --24 70 46 15 --30 ----------36 -----42 -----48 -----54 -----60 -----NOTES: 1. Source of data is NGPSA Data Book. 2. ‘d’ is inside diameter of smaller outlet. 3. ‘D’ is inside diameter of larger outlet.
3 3 4 5 6 9 12 15 18 20 24 26 30 32 35 --------
2 3 3 4 5 7 9 12 14 16 18 20 23 25 27 --------
Dimensions (i.e. Minimum Wall Thickness) of welded and seamless Pipe, Fittings & Flanges Nominal Pipe Outside Size in Diameter SCHEDULE / THICKNESS in INCH 5S 10S 40S 80S 1/8 0.405 --0.049 0.068 0.095 1/4 0.540 --0.065 0.088 0.119 3/8 0.675 --0.065 0.091 0.126 1/2 0.840 0.065 0.083 0.109 0.147
1 1 2 2 3 4 5 6 7 8 9 10 11 12 13 --------
1 1 2 2 3 4 5 6 7 ---------------
-----1 2 2 2 ---------------
3/4 1 1 1/4 1 1/2 2 2 1/2 3 3 1/2 4 5 6 8 10 12 14 O. D 16 O. D 18 O. D 20 O. D 22 O. D 24 O. D 26 O. D 28 O. D 30 O. D 32 O. D 34 O. D 36 O. D 42 O. D
1.050 1.315 1.660 1.900 2.375 2.875 3.5 4.0 4.5 5.563 6.625 8.625 10.75 12.75 14.0 16.0 18.0 20.0 22.0 24.0 26.0 28.0 30.0 32.0 34.0 36.0 42.0
0.065 0.065 0.065 0.065 0.065 0.083 0.083 0.083 0.083 0.109 0.109 0.109 0.134 0.156 0.156 0.165 0.165 0.188 0.188 0.218 --0.065 0.065 0.065 0.065 0.065 0.065
0.083 0.109 0.109 0.109 0.109 0.120 0.120 0.120 0.120 0.134 0.134 0.148 0.165 0.180 0.188 0.188 0.188 0.218 0.218 0.250 ----0.25 ---------
0.113 0.133 0.140 0.145 0.154 0.203 0.216 0.276 0.237 0.258 0.28 0.322 0.365 0.375 ---------------------------
0.154 0.179 0.191 0.200 0.218 0.276 0.300 0.318 0.337 0.375 0.432 0.500 0.500 0.500 ---------------------------
Note: Schedule 5S & 10S wall thickness do not permit Dimensions (i.e. Minimum Wall Thickness) of welded and seamless Pipe, Fittings & Flanges Nominal Pipe Outside Size in Diameter SCHEDULE / THICKNESS in INCH Sch Sch 10 Sch 20 30 Sch Std. Sch 40 1/8 0.405 ------0.068 0.068 1/4 0.540 ------0.088 0.088 3/8 0.675 ------0.091 0.091
1/2 3/4 1 1 1/4 1 1/2 2 2 1/2 3 3 1/2 4 5 6 8 10 12 14 O. D 16 O. D 18 O. D 20 O. D 22 O. D 24 O. D 26 O. D 28 O. D 30 O. D 32 O. D 34 O. D 36 O. D 42 O. D
0.840 1.050 1.315 1.660 1.900 2.375 2.875 3.5 4.0 4.5 5.563 6.625 8.625 10.75 12.75 14.0 16.0 18.0 20.0 22.0 24.0 26.0 28.0 30.0 32.0 34.0 36.0 42.0
------------------------------0.250 0.250 0.250 0.250 0.250 0.250 0.312 0.312 0.312 0.312 0.312 0.312 0.312
------------------------0.250 0.250 0.250 0.312 0.312 0.312 0.375 0.375 0.375 0.500 0.500 0.500 0.500 0.500 0.500 0.500
------------------------0.277 0.307 0.330 0.375 0.375 0.438 0.500 0.500 0.562 --0.625 0.625 0.625 0.625 0.625 0.625
0.109 0.113 0.133 0.140 0.145 0.154 0.203 0.216 0.226 0.237 0.258 0.280 0.322 0.365 0.375 0.375 0.375 0.375 0.375 0.375 0.375 0.375 0.375 0.375 0.375 0.375 0.375 0.375
0.109 0.113 0.133 0.140 0.145 0.154 0.203 0.216 0.226 0.237 0.258 0.280 0.322 0.365 0.406 0.438 0.5 0.562 0.594 --0.688 ------0.688 0.688 0.750 ---
Note: Schedule 5S & 10S wall thickness do not permit
DIMENSIONS OF WELDED AND SEAMLESS PIPE (i. e. MINIMUM DIMENSIONS OF WELDED ENDS OF FITTING AND FLANGES) Nominal Wall Thickness (in) Pipe Size Outside in Dia. Schedule
1/8 1/4 3/8 1/2 3/4 1 1 1/4 1 1/2 2 2 1/2 3 3 1/2 4 5 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 42
0.405 0.540 0.675 0.840 1.050 1.315
Sch Sch Sch 60 Extra 80 Strong --- 0.095 0.095 --- 0.119 0.119 --- 0.126 0.126 --- 0.147 0.147 --- 0.154 0.154 --- 0.179 0.179
1.660
--- 0.191 0.191 ---
---
--- 0.250 0.382
1.900 2.375
--- 0.200 0.200 ----- 0.218 0.218 ---
-----
--- 0.281 0.400 --- 0.344 0.406
2.875 3.5
--- 0.276 0.276 ----- 0.300 0.300 ---
-----
--- 0.375 0.552 --- 0.438 0.600
4.0 4.5 5.563 6.625 8.625 10.75 12.75 14.0 16.0 18.0 20.0 22.0 24.0 26.0 28.0 30.0 32.0 34.0 36.0 42.0
Sch Sch Sch Sch Sch X 100 120 140 160 X Strong --- --- --- ------- --- --- ------- --- --- ------- --- --- 0.188 0.294 --- --- --- 0.219 0.308 --- --- --- 0.250 0.358
--- 0.318 0.318 --- --- --- ------- 0.337 0.337 --- 0.438 0.531 0.674 --- 0.375 0.375 --- 0.500 --- 0.625 0.750 --- 0.432 0.432 --- 0.562 --- 0.719 0.864 0.406 0.500 0.500 0.594 0.719 0.812 0.906 0.875 0.500 0.500 0.594 0.719 0.844 1.000 1.125 0.875 0.562 0.500 0.688 0.844 1.000 1.125 1.312 1.000 0.594 0.500 0.750 0.938 1.094 1.250 1.406 1.000 0.656 0.500 0.844 1.031 1.219 1.438 1.594 --0.750 0.500 0.938 1.156 1.375 1.562 1.781 --0.812 0.500 1.031 1.281 1.500 1.750 1.969 --0.875 0.500 1.125 1.375 1.625 1.875 2.125 --0.969 0.500 1.218 1.531 1.812 2.062 2.344 ----- 0.500 --- --- --- --- ------- 0.500 --- --- --- --- ------- 0.500 --- --- --- --- ------- 0.500 --- --- --- --- ------- 0.500 --- --- --- --- ------- 0.500 --- --- --- --- ------- 0.500 --- --- --- --- -----
Note: All units are in inches
Pipe Size ½” ¾ 1’ 1.5” 2” 3” 4” 5” 6” 8” 10” 12” 14” 16” 18” 20” 24” 30”
Outside Diameter 21.34 26.67 33.41 48.26 60.33 88.90 114.30 141.30 168.28 219.08 273.05 323.85 355.60 406.40 457.20 508.00 609.60 762.00
Schedule/Thickness of Pipe (in mm) 5S 10S 20S 30S STD S40 1.66 ---2.77 2.77 1.66 ---2.87 2.87 1.66 ---3.38 3.38 1.66 ---3.68 3.68 1.66 ---3.91 3.91 2.11 ---5.49 5.49 2.11 ---6.02 6.02 2.11 ---6.55 6.55 2.77 ---7.11 7.11 2.77 -6.35 7.04 8.18 8.18 3.40 -6.35 7.80 9.27 9.27 3.97 -6.35 8.38 9.53 9.53 3.97 6.35 7.92 9.53 9.53 9.53 4.19 6.35 7.92 9.53 9.53 9.53 4.19 6.35 7.92 11.13 9.53 9.53 4.77 6.35 9.53 12.7 9.53 9.53 5.54 6.35 9.53 14.27 9.53 9.53 6.35 7.92 12.70 15.88 9.53 --
Pipe Size ½” ¾ 1’ 1.5” 2” 3” 4” 5” 6” 8” 10” 12” 14” 16” 18” 20” 24”
Outside Diameter 21.34 26.67 33.41 48.26 60.33 88.90 114.30 141.30 168.28 219.08 273.05 323.85 355.60 406.40 457.20 508.00 609.60
Schedule/Thickness of Pipe S80 XS S100 S120 3.73 3.73 --3.91 3.91 --4.55 4.55 --5.08 5.08 --5.54 5.54 --7.62 7.62 --8.56 8.56 -11.13 9.53 9.53 -12.70 10.97 10.97 -14.27 12.70 12.70 15.09 18.26 15.09 15.09 18.26 21.44 17.48 17.48 21.44 25.40 19.05 19.05 23.83 27.79 21.44 21.44 26.19 30.96 23.83 23.83 29.36 34.93 26.19 26.19 32.54 38.10 30.96 30.96 38.89 46.02
S60 ---------10.31 12.70 14.27 15.09 16.66 19.05 20.62 24.61 --
(in mm) S140 S160 -4.78 -5.56 -6.35 -7.14 -8.74 -11.13 -13.49 -15.88 -18.26 20.62 23.01 25.40 28.58 28.58 33.32 31.75 35.71 36.53 40.49 39.67 45.24 44.45 50.01 52.37 59.54
XXS 7.47 7.82 9.09 10.16 11.07 15.24 17.12 19.02 21.95 22.23 25.40 25.40 ------
30”
762.00
--
--
--
--
--
--
NB NOMINAL WALL THICKNESS FOR PIPE IN MM. INCH O.D SCH SCH SCH SCH SCH SCH SCH 5S 10S 10 20 30 40S/STD 40 0.25 13.70 -----2.24 2.24 0.375 17.10 -----2.31 2.31 0.5 21.34 1.55 2.11 ---2.77 2.77 0.75 26.67 1.55 2.11 2.11 --2.87 2.87 1.0 33.40 1.65 2.77 2.77 --3.38 3.38 1.25 42.16 1.65 2.77 2.77 --3.56 3.56 1.5 48.26 1.65 2.77 2.77 --3.68 3.68 2 60.32 1.65 2.77 2.77 --3.91 3.91 2.5 73.02 2.11 3.05 3.05 --5.16 5.16 3 88.90 2.11 3.05 3.05 --5.49 5.49 3.5 101.60 2.11 3.05 3.05 --5.74 5.74 4 114.30 2.11 3.05 3.05 --6.02 6.02 5 141.30 2.77 3.40 3.40 --6.55 6.55 6 168.27 2.77 3.40 ---7.11 7.11 8 219.07 2.77 3.76 -6.35 7.04 8.18 8.18 10 273.05 3.40 4.19 -6.35 7.8 9.27 9.27 12 323.85 3.96 4.57 -6.35 8.38 9.52 10.31 14 355.60 3.96 4.77 6.35 7.92 9.52 9.52 11.12 16 406.40 4.19 4.77 6.35 7.92 9.52 9.52 12.70 18 457.20 4.19 4.77 6.35 7.92 11.12 9.52 14.27 20 508.00 4.77 5.54 6.35 9.52 12.7 9.52 15.03 22 558.80 4.77 5.54 6.35 9.52 12.7 9.52 15.87 24 609.60 5.54 6.35 6.35 9.52 14.27 9.52 17.47 26 660.40 --7.92 12.70 -9.52 -28 711.20 --7.92 12.70 15.87 9.52 -30 762.20 6.35 7.92 7.92 12.70 15.87 9.52 -32 812.80 --7.92 12.70 15.87 9.52 17.47 34 863.60 --7.92 12.70 15.87 9.52 17.47 36 914.40 --7.92 12.70 15.87 9.52 19.05
NB NOMINAL WALL THICKNESS FOR PIPE IN MM. INCH SCH SCH SCH SCH SCH SCH SCH SCH 60 80S / 80 100 120 140 160 XXS XS
0.25 -0.375 --
3.02 3.20
---
---
---
---
---
---
0.5 0.75 1.0 1.25 1.5 2 2.5 3 3.5 4 5 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36
3.73 3.91 4.55 4.85 5.08 5.54 7.01 7.62 8.08 8.56 9.52 10.97 12.70 12.70 12.70 12.70 12.70 12.70 12.70 12.70 12.70 12.70 12.70 12.70 12.70 12.70 12.70
------------12.70 15.08 17.47 19.05 21.44 23.83 26.19 28.57 30.95 -------
------------15.08 18.25 21.44 23.83 26.19 29.36 32.54 34.92 38.89 -------
---------11.12 12.70 14.27 18.25 21.44 25.4 27.79 30.96 34.92 38.1 41.27 46.02 -------
------------20.63 25.4 28.57 31.75 36.53 39.67 44.45 47.62 52.37 -------
4.77 5.55 6.35 6.35 7.14 8.74 9.52 11.12 -13.49 15.87 18.25 23.01 28.57 33.32 35.71 40.49 45.24 50.01 53.97 59.54 -------
7.47 7.82 9.09 9.70 10.16 11.07 14.02 15.24 16.15 17.12 19.05 21.95 22.23 25.40 25.40 -------------
------------10.31 12.70 14.27 15.09 16.65 19.05 20.62 22.22 24.61 -------
DISTANCE BETWEEN EDGE TO EDGE OR CENTER TO EDGE SIZE Dimensions “RADIUS” or “HEIGHT” of FITTINGS DIA O.D. Circumference 90 ELL 45 EQ. CAP RED. ELL TEE 2 60 190 76 35 63 38 76 2.5 73 230 95 44 76 38 89 3 89 283 114 51 86 51 82.5 4 114 348.2 152 58 105 64 102
6 8 10 12 14 16 18 20 24 26 28 30 34 36 40 42
168 219 273 324 356 406 457 508 610 661 712 768 813 915 1016 1067
528 690 858 1018 1118.5 1215 1436 1600 1920 2077 2237 2413 2554 2874 3192 3352
229 305 381 457 533 610 686 762 914 991 1067 1143 1218 1371 1514 1600
95 127 159 190 222 254 286 317 381 406 438 470 501 563 632 660
143 178 216 254 279 304 343 381 432 495 521 568 597 673 749 762
DISTANCE BETWEEN EDGE TO EDGE CENTER TO EDGE SIZE WNRF DIA 150 # 300 # 400 600 900 1500 # # # # 2 64 70 73 73 102 102 2.5 70 76 79 79 105 105 3 70 79 83 83 102 117 4 76 86 89 102 114 124 6 89 98 103 117 140 171 8 102 111 117 133 162 213 10 102 117 124 152 184 254 12 114 130 137 136 200 282 14 127 143 149 165 213 293 16 127 146 152 176 216 311 18 140 159 165 184 229 327 20 145 162 168 190 248 356 24 152 168 178 203 252 406 26 121 184 178 222 286 -28 125 197 178 235 293 -30 137 210 219 248 311 -34 144 --- 248 330 -36 157 --- 263 362 --
89 102 127 152 165 178 203 229 267 267 267 267 267 267 267 305
OR
2500 # 127 143 168 191 273 318 419 464 -----------
140 152 178 203 330 356 381 508 508 610 610 610 610 610 610 610
40 42
164 171
---
---
264 279
364 371
---
---
TABLE: SPACING BETWEEN TWO BARE PIPES Dia. ½” ¾” 1” 1.5” 2” 3” 4” 6” 8” 10” 12” 14” 16”
1/2” 85 95 100 115 120 140 165 195 225 260 295 330 360
¾”
1”
1.5”
2”
3”
4”
100 100 115 120 145 165 200 230 260 300 330 365
105 120 125 145 170 200 235 265 305 335 365
125 130 155 175 210 240 270 310 340 375
140 160 180 215 245 280 315 345 380
175 195 230 260 295 330 360 395
210 240 275 305 345 375 405
6”
270 300 330 370 400 435
8”
325 360 395 425 465
4.12
Plant Layout
General: The bases of design establish the factors that must be included in process piping design. The preparation of the piping layout requires a practical understanding of complete piping systems, including material selections, joining methods, equipment connections, and service applications. The standards and codes previously introduced establish criteria for design and construction but do not address the physical routing of piping. This section contains miscellaneous considerations related to piping systems layout. The following items should be considered when planning piping layout on production plant. Safety of personnel. Compatibility with vessel, equipment, and skid arrangement Accessibility to equipment. Use of natural supports. Necessity of suitable walkways. Plant Layout Design System P& IDs; specifications; and equipment drawings showing the equipment locations and distance, nozzle locations and pressure ratings are needed to develop the piping plant layout. A completely dimensioned plan drawing showing the pipe routing from one point of connection to another with all appurtenances and branches of piping is prepared. The layout design also deals with piping support. Piping on racks is normally designed to bottom of pipe (BOP) elevations. Horizontal and parallel pipe running at different elevations are spaced for branch connections and also for independent pipe supports. Interferences with other piping systems; structural work; electrical conduit and cable tray runs; heating, ventilation and air conditioning equipment; and other process equipment not associated with the process of accounted for in pipe clearances. Composite drawings of the facility are used to avoid interferences,. Following figures presents a simple piping layout. Communications between engineering disciplines is properly maintained. Lay lengths and other restriction of in-line piping equipment and other system equipment constraints are considered. Valves and other equipment such as flow instrumentation and safety relief devices have specific location requirements such as minimum diameters of straight run up- and downstream, vertical positioning and acceptable velocity ranges that require pipe diameter changes. Manufacturers should be consulted for specific requirements. Piping connections to pumps affect both pump operating efficiency and pump life expectancy. The plant layout design follows the pump manufacturer's installation requirements and the Hydraulic Institute Standards, 14th Edition to reduce the effects. Followings are additional guidelines. The project process engineer is consulted when unique piping arrangements are required. Miscellaneous routing considerations are: Providing piping insulation for personnel protection, Access for future component maintenance, Heat tracing access, Hydrostatic test fill and drain ports, and Air vents for testing and start-up operations. System operability, maintenance, safety, and accessibility are the considerations that are addressed in the plant layout design with respect to the followings aspects at least: Valve Location Considerations: 1. Control valves: Control valve is installed with a minimum of 3 diameters of straight run both
upstream and downstream, and install vertically upright. 2. Butterfly and check valves: Butterfly and check valves are installed with a minimum of 5 diameters of straight run upstream. 3. Non-control valves: Non-control valves are installed with stems in the horizontal to vertical positions and avoid head, knee, and tripping hazards. 4. Chemical service valves are located below the eye level. 5. All valves are provided with a minimum of 100 mm (3.94 in.) hand clearance around all hand wheels to, allow space for valve parts removal or maintenance, and to avoid creating water hammer conditions. Pump Connections Considerations: Piping is independently supported from the pump. The pump suction is continuously flooded, has 3 diameters of straight run, uses long radius elbows, and can accommodate a temporary in-line strainer. An eccentric reducer, flat side up, is provided when a pipe reduction is required at the pipe suction to avoid cavity formation. Flanges mating to flat face pump flanges are also flat faced and use full-faced gaskets and common steel bolting. Elevations: Piping should not be installed on grating or flooring. It should have adequate clearance for maintenance. Overhead piping should be arranged to provide sufficient personnel head clearance. Basically, units and equipment shall be arranged in the smallest possible space, consistent with operability, safety, case of maintenance and foundation requirement and using the most optimum piping material, structural steel, concrete, cables etc. Space shall be left within the units for the future expansion when specially requested and other purpose as mentioned below: 1. Maintenance Access: In the process areas, spacing between various equipment and overhead clearances are to be based within the following guidelines: a) Mobile Maintenance Equipment Access: Plant design and arrangements are based on assumption that mobile maintenance equipment such as cranes, rolling platforms, portable ladders, portable lifts are available and can be used where practicable. Building in maintenance facilities is not required for grade mounted or near grade mounted equipment unless specifically asked by the clients. Break up flanges shall be provided where required for disconnecting pipe work for eventual maintenance of tube bundle. b) Heavy Crane Access: Equipment, structures, shall be arranged to permit crane access to service air coolers over pipe ways, compressors and exchangers. All exchanger’s tube bundles shall be “jacked out” against the shell. No permanent handling arrangement shall be provided for the exchangers when layout permits access by crane of sufficient size to hold and lower the bundle to the ground. A clear space for tube bundle removal shall be provided. This includes a minimum clearance of tube bundle length plus 1000 mm in front of the exchanger measured from the tube sheet and a clearance to move the exchanger out of the area on a wheeled trolley. Catalyst Loading: Clear access for mobile maintenance equipment shall be provided to all vessels charged with catalyst or other bulk materials. In addition, space shall be provided for local storage of fresh and spent catalyst during loading and unloading operations. Access to pumps: Clear access of 3 M both vertically and horizontally shall be provided centrally under main pipe ways for small mobile equipment to service pumps. Access to Column: There should be clear access at grade level on all side of tall-elevated equipment, such as columns, for lowering external and internal fittings. Access from a portable
stepladder, rolling platform or portable man lift at grade is permitted for certain instruments, pieces of equipment and shut–off valves. 2. Layout & Access Requirements for Platforms Ladders and Stairs: a). Two means of access (i.e. two ladders or one ladder and one staircase) shall be provided at any elevated platform, which serves three or more vessels. Lack of such means might prevent the escape of a person in the event of an emergency. Platforms, ladders and stairways shall be the minimum, consistent with access and safety requirements. Platform at large elevated structure must be provided with followings: Duel access (i.e. one staircase and one ladder) shall be provided at large elevated structure if any part of platform has more than 22.65M (75 ft.) of travel. b) Air coolers shall have platforms with inter connected walk – ways provided to service valve, fan motors and instruments. When fired heaters are located adjacent to one another, they should have interred connecting platforms on the upper and lower section. Inter-connecting platforms between towers may be provided taking into consideration expansion of towers. c) Platforms with stair access shall be provided for: Locations at which normal monitoring (once a day or more) samples are taken. d) Locations where vessels or equipment items have operator attention such as compressors, heaters, boilers etc. e) Platforms with ladder access shall be provided for Points, which require occasionally operating, access including, valves, spectacle blind and motors. Man ways above grade on equipment. f) Ladder location: Wherever practicable, ladders shall be arranged so that users face towards equipment or structures rather than facing open space.
Figure 2-4. Remediation Process Piping Plan (Source: SAIC,)
GENERAL C LEARANCE AND
ACCESSIBILITY:
Additional clearance and accessibility requirements are as under: Roads: Fire hydrants, monitors, extension steams of underground valves etc. shall not be located within 100 mm of the edge of the road. Tank Farm: Tank farms are off – plot areas used for storing and transferring of stock in various types and sizes of tanks. In general, storage tank clearances shall conform to the local codes or the relevant API code.
Figure 2-5. Isometric View (Source: SAIC,) Clearance for Fired Heaters: Fired Heaters shall be located near the battery limit at a minimum distance of 15 meter from any process equipment, which may be a source of spillage or leakage of gas and liquid and 90 meter from any explosive product. Heater Stacks must be 6 M higher than any operating platform within 25 M radius. Exchangers: Clearance and working space between horizontal exchanger’s shells and adjacent piping extremities where operation is required shall be 900 mm. Clearance distance between horizontal exchanger flanges where no piping or equipment operation is required shall be 600 mm. Pumps: Clearance and working space requirements between pumps and adjacent piping extremities shall be 600 mm. Compressors: Centrifugal and axial compressors require access on both sides. Reciprocating compressors require space for pulling pistons. This is usually adequate for walkway access. Pipe Routing: Pipe shall be arranged in an orderly manner and routed as direct as practical. Thermal Expansion: Arrangement shall provide for flexibility of lines to take care of
thermal expansion and contraction. Large reactions or moments at equipment connection shall be avoided. Critical Piping: Where dynamic loading, limited pressure drop or other severe service conditions apply; particular care shall be used in routing the piping. Dynamic loading may be expected when pulsation flow (such as reciprocating compressors), high velocity flow flashing fluid, fluctuating temperature or pressure or mechanical vibration (including wind) conditions exist. Piping subject to possible dynamic loading shall be carefully designed and checked to ensure that the size, configuration, mechanical strength, supports and restraints shall prevent excessive stress or vibration. Other severe services: Other severe services include erosive, corrosive, high or low temperature or pressure conditions or any fluids containing solids. Many such services require alloy or their special materials. Piping in these services shall be routed to minimize the effects of service severity and make most practical use of required special materials. Piping at Control valves: Special attention must be paid to any control valve, which will contribute to excessive noise or vibration due to aerodynamics, which must be carefully analysed and designed so that its size and configuration downstream of the control valve will minimize these conditions. Special attention should also be paid for ejector piping and high vacuum piping. Pipe ways: Pipe ways shall generally be run overhead for on plot units and shall generally not be more than three decks high. Pipe ways are the present need that includes pipes, instrument tray and electrical cable tray plus 25%. Line Routing: As far as practical piping shall run at the different elevations designated for north–south and east–west banks and shall change elevation at change in direction. Vessel Piping: Piping at columns shall be located redial about the column on the pipe wayside. Man ways and platforms shall be located on the access side away from pipe way. Water Draw off boots: Water draw off boots on elevated horizontal vessels may be extended a reasonable amount to place the centre of gauge glass and level controller not over 1700 mm from grade, platform or ladder accesses. Vent and drain connection: A valve blinded atmospheric vent shall be provided at vessel high points with access provided for valve operation. Drains with valves provided to vessels shall be gravity drains to underground systems with open connections terminating 50 mm. below drain. However, whenever blind flange / plug have been used, gap of 100 mm. should be provided. Relief Valves: Relief valves required for pressure vessels shall be as indicated on the piping and the instrument diagrams. Davits or other suitable means shall be provided to lower pressure vessel relief valves larger than 2” inlet size when not within reach of mobile equipment. Relief valves discharging in to a flare system shall be elevated to provide self-draining. Relief valves discharging vapour to atmosphere must be provided with a pipe stack, which must end at least 3 M above any platform within 8 M radius. Where indicated in process P & ID, a drain valve with, drip leg shall be provided at the bottom of the stack. Adequate supports shall be provided and designed to handle dead weight, wind and thrust loads. Exchanger Piping: Piping shall not run in the way of built–in or mobile handling
facilities. One wrench clearance shall be provided at exchanger flanges. Pump Suction Piping: Pump suction piping shall be arranged with particular care to avoid vapour pockets or unnecessary pressure drop. Eccentric reducers, properly oriented to avoid vapour packets, shall be used for line size reductions. (Temporary suction screens shall be provided unless permanent strainers are required between suction line block valves and pump nozzles. Pump Location: Centreline of all discharge pump nozzles shall be line up. Access to Pumps & Turbines: Piping at pumps and turbines shall be arranged to provide maintenance access around pumps and turbines. Removable spool pieces shall be provided as appropriate to permit maintenance without major disassembly. Weight and thermal Stresses: Suitable supports or anchors shall be provided and located for piping to pumps and turbines so that excessive weight and thermal stresses will not be applied to the casings and access areas around pumps and turbines are kept free. Careful design consideration shall be given to piping configuration to minimize these stresses. Compressor Piping: Large centrifugal or reciprocating compressors shall be of a raised floor design so that piping and auxiliaries can be located below main operating platform. Vibration: Particular attention shall be given to design of piping subject to vibration from dynamic loading, associated with reciprocating compressors. Suction and discharge lines shall be securely clamped and small piping around compressors and on the same support as suction and discharge lines shall be well braced to reduce vibration. Reciprocating compressor: Reciprocating compressor suction and discharge piping shall be run on sleepers at grade, if at all possible. This arrangement permits simple and effective clamping of the lines. Removable spool pieces shall be provided at compressors where needed to permit maintenance without major piping disassembly. Suction piping to centrifugal compressors should be designed to allow sufficient straight length i.e., 5 D minimum of pipe immediately ahead of suction nozzle, to allow dissipation of undesirable flow distortion caused by elbows, valves or other fittings upstream and velocity in line. Burner piping at fired heaters: Burner piping shall be kept clear of all access and observation openings. Adequate space for removal of heater tubes shall be kept for its maintenance, piping to the burners shall be made using unions, flexible connectors to provide for easy and convenient removal of burners for maintenance. Supply piping of fuel gas shall be arranged for equal flow distribution and shall be provided with condensate legs, knockout pots or other approved methods for the collection and elimination of condensate. Steam Traps: All steam traps discharging to a closed system are to have a block valve upstream and downstream of the trap. A bypass valve shall be installed around the block valves and a stop valve shall be installed at a low point ahead of the upstream block valve. Check valve shall be installed on the upstream of the steam trap, in case of discharging to a closed system. Valve Lactation & Accessibility: All valves requiring attention during normal operation shall be operable either from grade or platform or fixed ladder. Non–operating valves and instruments connections may have fixed ladder. Non –operating valve is one that is used to shut off a piece of equipment or system for maintenance. Installation of drain operation valve should be avoided as far as possible. Orifice Runs: Horizontal meter runs are preferred. Necessary straight runs upstream and downstream
orifice plates shall be provided in accordance to API RP 550 Part- I. Sufficient clearance at orifice flange for installation of instrument piping and seal pots, where required, shall be provided. Offsite and Yard piping: In general the pipes shall be laid at grade level on sleepers at 300 mm high from grade level. Pipes at crossing of roads shall be under culverts in general. Pipe sleeves may be considered where one or two pipes are to cross the road.
A
Flange
A = R1 + R2 + 25 mm R1 = Radius of Smaller Pipe R2 = Radius of Bigger Pipe Flange Underground Piping: Branches, which rise above grade level and originate from underground header, are to have a pair of flanges approximately 300 mm grade level. Overhead clearances: Equipment, structure, platforms, piping & its supports shall be arranged to provide the following clearance overhead: Over railroads, top of rail to bottom of any obstruction 7.25 m Over plant roads for major mobile equipment 7.25 m Bottom of pipe Over secondary roads and mobile equipment 5.5 m Bottom of pipe over grade inside battery limit and at pump row 4m Over walk–ways, pass–ways platforms to nearest obstruction 2.5 m Over exchangers shell cover channel end. 2M Horizontal clearances: Equipment, structure, platforms, piping & its supports shall be arranged to provide the following clearance horizontally: Between exchangers (aisles between piping) 1m Around pumps (aisles between piping) 1m Fired heaters to flammable stock handling pump 16 m Fired heaters to other equipment not closely associated with heaters. 16 m At driver end of pumps, where truck access is required 4m
At driver end of pumps where truck access is not required 2m Distance between shells of adjacent vessels / exchangers at grade. 1.5 m Pipe berthing underground 500 mm Minimum clear gap between Bare pipes above ground = X mm Where, X = (Small pipe Dia. +Bigger pipe flange Dia. + 25 mm.) Equipment spacing (Centre -to- centre distance): Small pumps mounted on common foundations (3.7 kW & less) 800 mm Medium pumps (22.5 kW & less) 1m Larger pumps (Above 22.5 kW) 2m Exchangers and other equipment on structures Minimum clear distance 1m Platforms: Towers, vertical & horizontal vessels 800 mm Distance of platforms below Centreline of manhole flange 1-1.2 m Width of manhole platform from manhole cover to outside edge 1m Platform extension beyond centreline of manhole side Horizontal exchanger: Clearance in front channels or bonnets flange 1500mm (Heat exchanger tube bundle length + 1 m) Bundle removal space Min. clearance from edge of flanges = Y Where, Y = (300 mm + Length of tube bundle) Vertical exchanger: Distance of platform below top flange of channel or bonnet 1500mm Furnaces: Width of the platform at side of horizontal and vertical tube furnace (Min.) 1000mm Width of platform at ends of horizontal tube furnaces (min.) 1000mm
4.13
Design Example 1
A facility requires an up gradation to their existing wastewater treatment system. The treatment system is required to reduce the dissolved metal content of two process waste water units before introduction into a biologically based central treatment plant. The wastewaters are produced from a plating process (Process A) and from the finishing stages of a metal fabrication facility (Process B). The latter includes metal cleaning using organic solvents and painting operations. The renovation includes the splitting of an existing, covered, concrete wet well (P1560). Half of the wet well will now act as an influent wet well (P1560) to a new treatment train and the other half will act as the clear well (P1510) for the effluent from the new treatment system. The new treatment system will include a low-profile air stripper to reduce solvent concentrations followed by a ferrous-based precipitation reactor and associated flocculation tank and clarifier. Following Figures are the flow diagram of the proposed pre-treatment system renovation, and the piping and instrumentation diagram, the general equipment arrangement with the anticipated piping layout. The influent to the pre-treatment system averages 3.79 x 10-3 m3/s with a maximum future flow of 5.36 x 10-3 m3 /s and process temperatures of 16C-minimum, 23.9C normal, and 46C-maximum. The average pH is 5.4 due to the presence of chromic and sulphuric acids, although occasional upsets have produced pH as low as 3.6. The pollutant concentrations are summarized in following Table.
Fig: Isometric Piping Drawing
Figure: Design Example Process Flow Diagram
ig: Piping and Instrumentation Diagram
Sketch: Isometric Drawing
5 Piping Components Complete Piping System is an assembly of pipes, fittings, flanges, valves and other piping components to be used for conveyance of fluids (liquids and gases) flow with pressure, temperature and hazardous materials in specialized applications from one location to another. Piping Components include supports also but does not include supporting structures, building frame, foundations or equipment. Any material or work required to install on the piping system is called piping components. These are mechanical elements suitable for joining or assembling into a pressure tight fluid containing piping system. Piping Components include but not limited to pipes, tubes, fittings, flanges, valves, gaskets, bolt-nuts, expansion joints, compensators, hose pipes, traps, strainers, separators, control valves, safety valves, blind flanges, spectacle blinds, elbows, adapters, unions, tees and drip rings.
5.1 Pipe and Tube Pipe: A pipe is a tubular section or hollow cylinder used mainly to convey substances (liquids, gases, slurries, powders, granules of solids) flowing through it. It is also used for structural applications like Jacket and Platform Deck as hollow pipe is far stiffer per unit weight than solid members. The term Piping is used to describe conveyance of water, gas, or liquid and fluids in specialized applications in commercial or industrial environments with high-performance. Pipe is specified by a nominal diameter with a constant outside diameter (OD) and a schedule that defines the thickness. Pipe has rigidity and permanence, whereas a Hose or Hosepipe is usually portable and flexible. Pipe assemblies are always constructed with the use of fittings such as elbows, tees and flange, while tube is formed or bent into custom configurations.
Tube: A tube is a long hollow cylinder used to convey fluids (liquids or gases). The terms "pipe" and "tube" are almost interchangeable, but still has although minor distinctions. The term tubing is sometimes used for lighter-weight piping, especially flexible enough to be supplied in coiled form. Tube is specified by the OD or ID and wall thickness. The tubes are specified by actual inside diameter or outside diameter and wall thickness. However, Tube assemblies are also constructed with the use of tube fittings. Applicable Codes and Standards IS: 1230: Cast Iron Rain Water Pipe and Fittings IS: 1239: Specification for MS Tubes and other Wrought steel Pipes and Fittings. IS: 3589: Specification for MS Tubes and other Wrought Steel Pipes and Fittings ASTM A53: Black, hot-dipped and zinc-coated pipes (Seamless/Welded) ASTM A106: Carbon steel pipe for high temperature service (Seamless) ASTM A 135 Electric-Resistance-Welded Steel Pipe ASTM A179: Cold-Drawn Low-Carbon Steel Heat Exchanger and Condenser tube (Seamless) ASTM A192: Carbon Steel Boiler Tubes for High Temperature Service (Seamless) ASTM A209: Carbon-Molybdenum Alloy Steel Boiler and Super heater Tube (Seamless) ASTM A210: Medium Carbon Steel Boiler and Super heater Tubes (Seamless)
ASTM A213:
Ferritic and Austenitic Alloy Steel Boiler, Super heater
and Heat Exchanger Tubes (Seamless) ASTM A312: Austenitic stainless steel pipe (Seamless/Welded) ASTM A333: Specification for Seamless and Welded Steel pipes for LTCS. ASTM A334: Carbon and Alloy Steel Tubes for LTCS ASTM A335: Ferritic Alloy Steel pipe for High Temperature service ASTM A358: Austenitic Chr-Nil Alloy Steel pipe for High Temperature Service (E.Fs.W) ASTM A409: Austenitic Steel pipes for high temperature service ASTM A450: Requirements for Carbon, Ferritic and Austenitic Alloy Tubes. ASTM A524: Carbon Steel pipe for atmospheric or low temperature service ASTM A530: Requirements for specialized Carbon and Alloy Steel pipe. ASTM A671: Steel Pipe for atmospheric or low temperature service (E.Fs.W) ASTM A672: Steel pipe for High Pressure Service at moderate temperature (E.Fs.W) ASTM A691: Carbon and Alloy Steel pipe for high-pressure service (E.Fs.W) ASTM B93-11: Seamless Low Carbon Steel Hydraulic Line Tubing ASTM SB-42: Seamless Copper Pipe, Standard sizes ASTM SB-43: Seamless Red Brass Pipe, Standard Sizes ASTM SB-75: Seamless Copper Tube ASTM SB-163:Seamless Nickel and Nickel Alloy Condenser and Heat Exchanger Tubes ASTM SB-165:Nickel-Copper Alloy (UNS N04400) Seamless Pipes and ASTM SB-167: Ni-Chr-Iron Alloys (UNS) Seamless Pipe and Tubes ASTM SB-210: Aluminium and Aluminium-Alloy Seamless Tubes ASTM SB-234: Aluminium-Alloy Tubes for Condensers and Heat Exchangers ASTM SB-241:Aluminium-Alloy Seamless Pipe and Seamless Tube ASTM SB-337: Titanium and Titanium Alloy Pipes ASTM SB-338:Seamless Titanium Alloy Tubes for Condensers and Heat Exchangers ASTM SB-395:Copper-Alloy Heat Exchanger and Condenser Tubes ASTM SB-407: Nickel-Iron-Chromium Alloy Seamless Pipe and Tube ASTM SB-444: Ni-Cr-Molybdenum-Columbium Alloy (UNS N06625) Pipe and Tube ASTM SB-466: Seamless Copper-Nickel Pipe and Tube ASTM SB-523:Zirconium and Zirconium Alloy Tubes (Seamless/ Welded) ASTM SB-658: Zirconium and Zirconium Alloy Pipes (Seamless/Welded) ASTM SB-668: UNS N08028 Seamless Tubes
ASTM SB-829:General Requirement for Nickel-Alloy Seamless Pipe and ASTM F1173: Epoxy thermo set pipe conveying seawater in a marine environment. API 5L: Specification for Carbon Steel Line Pipe (Seamless/Welded) API 5LS: Carbon Steel Line Pipe (Spiral Welded) API 5LX: Specification for CS High Pressure Line Pipe API 15LR: Low-pressure fibreglass reinforced thermo set pipe. NACE: Sulphide Stress Corrosion Cracking Resistant Metallic Material for oil field (MR-01-75) Equipment ASTM D 2310 Machine-made reinforced thermosetting pipe. ASTM D 2996 Filament wound fibreglass-reinforced thermo set pipe. ASTM D 2997 centrifugally cast reinforced thermo set pipe. ASTM D 3517 Fibreglass reinforced thermo set pipe conveying water. ASTM D 3754 Fibreglass reinforced thermo set pipe conveying industrial process liquids and wastes. Pipe Manufacturing: There are three processes for metallic pipe manufacture. (i) Centrifugal casting of hot alloyed metal. (ii) Seamless (SMLS) pipe is formed by drawing a solid billet over a piercing rod to create the hollow shell. (iii) Electric Resistance Welded ("ERW"), and Electric Fusion Welded ("EFW") pipe is formed by rolling plate and welding the seam. The weld flash is removed from the outside or inside surfaces using a scarfing blade. Welded pipe often has tighter dimensional tolerances than seamless, and is cheaper. Large-diameter pipe is ERW, EFW or Submerged Arc Welded ("SAW"). (a) Seamless Pipe: The Seamless Pipe of Material Specifications API 5L & 5LX; ASTM A53; ASTM A106; ASTM A333; ASTM A335 of sizes up to 762 mm O. D. are made by these processes. (i) In the seamless pipe-making process tube rounds are heated in a furnace, after which they are pierced, then rolled by the Mandrel or Plug-Mill process into pipes and tubes of specified diameters and wall thicknesses. Seamless tubular products are generally hot-rolled, but can also be supplied cold-drawn (up to 273 mm O. D.) when required. (ii) The “Push-Bench” process can also be used in the manufacture of seamless pipe. In this process, a steel billet is furnace heated to the plastic state and partly punched at one end to take a mandrel. The billet is then forced by the mandrel through a series of gradually reducing dies, until the required outside diameter has been attained, the I.D. being determined by the size of the mandrel. (b) Electric Resistance Welding (E. R. W.) Pipe: The E R W Pipe of Material Specifications API 5L & 5LX; ASTM A53; ASTM A135; ASTM A252; ASTM A333 of sizes up to 610 mm O. D. are made by this process. The E R W Pipe is manufactured with a process is described below. At the pipe mill, the strip is uncoiled, levelled and crop-sheared. It is then trimmed on both sides simultaneously to correct width and immediately fed into the forming and welding line. During the process, the strip is closely checked for surface defects. A series of cold forming rolls changes the strip progressively into tubular form with abutting edges on top. The longitudinal edges are joined by high frequency electric resistance welding. The weld is then heat treated electrically. Special devices remove inside and outside flash from the weld to give uniform wall thickness of the pipe. The welded part is then heat-treated by post annealing to ensure adequate ductility at the weld and adjacent zone. The pipe is passed through a series of cold sizing rolls to progressively reduce the diameter to accurate size. This operation also increases strength and improves surface condition. The pipe is then
cut to specified length by a flying cut-off machine. After the straightening operation, ends of the pipe are cropped, then squared or bevelled depending on end finish requirements. The pipe is then hydrostatically tested to specified pressure. Also test specimens are taken during the process to check chemical and mechanical properties. Each length of pipe is inspected by the ultrasonic method on the weld and checked as to diameter, wall thickness, surfaces, end finish, camber and concentricity. The length and weight of pipe is measured and recorded and protective coating is applied on the outside surface. (c) Submerged Arc Welded (S A W) Pipe: The Submerged Arc Welded (S A W) Pipe of Material Specifications API 5L, 5LX & 5LU; and ASTM A53; of sizes up to 1820 mm O. D. are made by these processes. Steel plates are first U-shaped then O-formed by a hydraulic press. The seam is welded from inside and outside automatically by the submerged-arc process. Hydraulic expansion gives the pipe precise diameter and roundness and relieves residual stresses caused by forming and welding. Pipe Sizes & Dimensions: There are two common methods for designating pipe outside diameter (OD). The North American method is called NPS ("Nominal Pipe Size") and is based on inches (frequently referred to as NB ("Nominal Bore")). The European version is called DN ("Diameter Nominal" / "Nominal Diameter") and is based on millimetres. Designating the outside diameter allows pipes of the same size to be fit together no matter what the wall thickness. As per American Standard, Pipe size is specified with two non-dimensional numbers: (i) a Nominal Pipe Size (NPS) for diameter in inches, and (ii) Thickness or Schedule (Sch.). DN (Nominal Diameter) is the European designation of pipe size equivalent to NPS, in which sizes are measured in millimetres. The term NB (Nominal Bore) is frequently used with NPS. The American Standards Association (ASA) created a system of schedule numbers that designated wall thicknesses of pipe based on smaller steps between sizes. The Pipe Schedule, like Standard (STD), Extra Strong (XS), Double Extra Strong (XXS) standard, extra-heavy (XH), and double extra-heavy (XXH) relates to a given pressure rating. STD is identical to SCH 40S, and 40S is identical to 40 for NPS 1/8 to NPS 10, inclusive. XS is identical to SCH 80S, and 80S is identical to 80 for NPS 1/8 to NPS 8, inclusive. XXS wall is thicker than schedule 160 from NPS 1/8" to NPS 6" inclusive, and schedule 160 is thicker than XXS wall for NPS 8" and larger. Stainless steel pipes have thinner walls with much less risk of failure due to corrosion. Accordingly, thinner schedules, like 5S and 10S, which are based on the pressure requirements. The "S" designation, like Sch 10S", most often indicates stainless steel pipes. However some stainless steel pipes are available in steel designations, so strictly speaking the "S" designation only differentiates B36.19M pipe from B36.10M pipe. For NPS ⅛ to 12 inches, the NPS and OD values are different. The OD of an NPS 12” pipe is actually 12.75 inches. The reason is that these NPS values were originally set to give the same inside diameter (ID) based on wall thicknesses standard at the time. However, as the set of available wall thicknesses evolved, the ID changed and NPS became only indirectly related to ID and OD. Tubing size is always the actual OD. For pipe sizes less than NPS 14 inch (DN 350), both methods give a nominal value for the OD that is rounded off and is not the same as the actual OD. For example, NPS 2 inch and DN 50 is the same pipe, but the actual OD is 2.375 inches or 60.33 millimetres. The only way to obtain the actual OD is to look it up in a reference table. For pipe sizes of NPS 14 inch (DN 350) and greater the NPS size is the actual diameter in inches and the DN size is equal to NPS times 25 (not 25.4) rounded to a convenient multiple of 50. For example, NPS 14 has an OD of 14 inches or 355.60 millimetres, and is equivalent to DN 350. Since the outside
diameter is fixed for a given pipe size, the inside diameter will vary depending on the wall thickness of the pipe. For example, 2" Schedule 80 pipe has thicker walls and therefore a smaller inside diameter than 2" Schedule 40 pipe. Table: Pipe sizes for NPS ½” to NPS 3” Wall thickness in inch and (mm) OD SCH SCH DN SCH NPS [in] SCH 40s 80s SCH SCH 5 10s (mm) 30 /40 /80 120 /10 /STD /XS 0.840 0.065 0.083 0.095 0.109 0.147 ½ 15 — (21.3) (1.65) (2.10) (2.41) (2.76) (3.73) 1.050 0.065 0.083 0.095 0.113 0.154 ¾ 20 — (26.6) (1.65) (2.10) (2.41) (2.87) (3.91) 1.315 0.065 0.109 0.114 0.133 0.179 1 25 — (33.4) (1.65) (2.76) (2.89) (3.37) (4.54) 1.900 0.065 0.109 0.125 0.145 0.200 1½ 40 — (48.2) (1.65) (2.76) (3.17) (3.68) (5.08) 2.375 0.065 0.109 0.125 0.154 0.218 0.250 2 50 (60.3) (1.65) (2.76) (3.17) (3.91) (5.53) (6.35) 3.500 0.083 0.120 0.188 0.216 0.300 0.350 3 80 (88.90) (2.108) (3.048) (4.775) (5.486) (7.620) (8.890)
SCH 160
XXS
0.188 (4.775) 0.219 (5.563) 0.250 (6.350) 0.281 (7.137) 0.343 (8.712) 0.438 (11.125)
0.294 (7.468) 0.308 (7.823) 0.358 (9.093) 0.400 (10.16) 0.436 (11.07) 0.600 (15.240)
Table: Pipe sizes for NPS 4 to NPS 8 OD NP DN [in] S (mm) 4
6 8
1 0 0 1 5 0 2 00
4.500 (114.3 0)
S CH 5
Wall thickness in inch and (mm) SCH SCH SCH S S S SCH SC 40s/40 80s/80 10s/10 CH 20 CH 30 CH 60 100 120 /STD /XS
0.083 0.120 — (2.108) (3.048)
6.625 0.109 0.134 — (168.28) (2.769) (3.404)
0.188 0.237 0.281 (4.775) (6.020) (8.560) —
0.280 — (7.112)
—
0.437 — (11.100)
0.432 — (10.973)
0.5 (14
8.625 0.109 0.148 0.250 0.277 0.322 0.406 0.500 0.593 0.7 (219.08) (2.769) (3.759) (6.350) (7.036) (8.179) (10.312) (12.700) (15.062) (18 Table: Pipe sizes for NPS 10 to NPS 24 Wall thickness in inch and (mm)
DN
OD
NPS
[in (mm)]
10
250
12
300
14
350
16
400
18
450
20
500
24
600
10.75 (273.05) 12.75 (323.85) 14.00 (355.60) 16.00 (406.40) 18.00 (457.20) 20.00 (508.00) 24.00 (609.60)
SCH 5s
SCH 5
SCH richs
SCH 10
SCH 20
SCH 30
SCH 40s/STD
0.134 (3.404) 0.156 (3.962) 0.156 (3.962) 0.165 (4.191) 0.165 (4.191) 0.188 (4.775) 0.218 (5.537)
0.134 (3.404) 0.165 (4.191) 0.156 (3.962) 0.165 (4.191) 0.165 (4.191) 0.188 (4.775) 0.218 (5.537)
0.165 (4.191) 0.180 (4.572) 0.188 (4.775) 0.188 (4.775) 0.188 (4.775) 0.218 (5.537) 0.250 (6.350)
0.165 (4.191) 0.180 (4.572) 0.250 (6.350) 0.250 (6.350) 0.250 (6.350) 0.250 (6.350) 0.250 (6.350)
0.250 (6.350) 0.250 (6.350) 0.312 (7.925) 0.312 (7.925) 0.312 (7.925) 0.375 (9.525) 0.375 (9.525)
0.307 (7.798) 0.330 (8.382) 0.375 (9.525) 0.375 (9.525) 0.437 (11.100) 0.500 (12.700) 0.562 (14.275)
0.365 (9.271) 0.375 (9.525) 0.375 (9.525) 0.375 (9.525) 0.375 (9.525) 0.375 (9.525) 0.375 (9.525)
Table: Pipe sizes for NPS 10 to NPS 24
NPS 10 12 14 16 18 20 24
SCH 40 SCH 60 0.365 (9.271) 0.406 (10.312) 0.437 (11.100) 0.500 (12.700) 0.562 (14.275) 0.593 (15.062) 0.687 (17.450)
0.500 (12.700) 0.562 (14.275) 0.593 (15.062) 0.656 (16.662) 0.750 (19.050) 0.812 (20.625) 0.968 (24.587)
Wall thickness in inch and (mm) SCH SCH SCH SCH 80 80s/XS 100 120 0.500 0.593 0.718 0.843 (12.700) (15.062) (18.237) (21.412) 0.500 0.687 0.843 1.000 (12.700) (17.450) (21.412) (25.400) 0.500 0.750 0.937 1.093 (12.700) (19.050) (23.800) (27.762) 0.500 0.843 1.031 1.218 (12.700) (21.412) (26.187) (30.937) 0.500 0.937 1.156 1.375 (12.700) (23.800) (29.362) (34.925) 0.500 1.031 1.280 1.500 (12.700) (26.187) (32.512) (38.100) 0.500 1.218 1.531 1.812 (12.700) (30.937) (38.887) (46.025)
SCH 140 1.000 (25.400) 1.125 (28.575) 1.250 (31.750) 1.437 (36.500) 1.562 (39.675) 1.750 (44.450) 2.062 (52.375)
Table: Pipe sizes for NPS 26 to NPS 36 Wall thickness in inch and (mm)
SCH 160 1.125 (28.575) 1.312 (33.325) 1.406 (35.712) 1.593 (40.462) 1.781 (45.237) 1.968 (49.987) 2.343 (59.512)
NPS
DN OD [in (mm)]
SCH 5s 26
650 26.000 — (660.400)
28
700
30
750
32
800
34
850
36
900
28.000 (711.200) 30.000 (762.000) 32.000 (812.800) 34.000 (863.600) 36.000 (914.400)
SCH 10s
SCH 10
—
0.312 0.500 0.375 (7.925) (12.700) (9.525)
0.312 (7.925) 0.250 0.312 0.312 (6.350) (7.925) (7.925) 0.312 — — (7.925) 0.312 — — (7.925) 0.312 — — (7.925) —
—
SCH 20 SCH 30
0.500 (12.700) 0.500 (12.700) 0.500 (12.700) 0.500 (12.700) —
SCH SCH SCH 40 40s/STD 80s/XS —
0.625 (15.875) 0.625 (15.875) 0.625 (15.875) 0.625 (15.875) 0.625 (15.875)
0.375 (9.525) 0.375 (9.525) 0.375 (9.525) 0.375 (9.525) 0.375 (9.525)
Pipe & Tube Manufacturing Tolerances: Specification
OD (mm) Size
10.29 to 48.26 48.26 to 114.30 ASTM A312 114.30 to 219.08 219.08 to 457.20 Up to 25.4 25.4 to
Permissible Variation + 0.40 / 0.80
Wall Thickness; WT Length (mm) (mm) Permissible Permissible Size Size Variation Variation ± 12.5% +6/0
+ 0.80 / 0.80 +1.60 0.80
/
-
+ 2.40 / 0.80 + 0.10 / D≤38.1 0.10 + 0.15 / - D≥38.1 +20% / 0
+3 / 0
0.500 (12.700) —
—
0.500 (12.700 0.688 0.500 (17.475) (12.700 0.688 (17.475) 0.750 0.500 (19.050) (12.700 —
38.1 38.1 to 50.8 50.8 to 63.5 ASTM A213 63.5 to 76.2 76.2 to 101.6 101.6 to 190.5 190.5 to 228.6 Up to ASTM A269 12.7
0.15 + 0.20 0.20 + 0.25 0.25 + 0.30 0.30 + 0.38 0.38
/ / -
+22% / 0
/ / -
+5/0
+ 0.38 / 0.64 + 0.38 / 1.14 + 0.19 / 0.13
± 15%
+ 3.2 / 0
For C. S. Pipe 10” and above Diameter; Length Tolerance + 50 mm / - 0 mm Pipe Mass in Kilograms per metre: Formula for calculation of approximate Pipe Mass in Kilograms per metre (kg/m) for steel round pipe and Tubing is as given below: M = (D - T) T X 0.02466 Where: m = mass to the nearest 0.01 kg/m. D = Outside Diameter in millimetres (mm). (To nearest 0.1 mm for O. D. up to 406.4 mm and nearest 1.0 mm for O. D. 457 mm and above) t= Wall Thickness to nearest 0.01 mm.
5.2
Pipe Fittings
Fittings are used in piping systems to connect straight pipe or tube in sections, to adapt to different sizes, shapes, turning, regulating or measuring fluid flow and other purposes. Fittings are a non-trivial part of piping systems and valves or flanges are technical fittings, which are discussed separately. While there are hundreds of specialized fittings manufactured, some common types of fittings are used widely in piping systems. The fittings should be forged and seamless and fittings with welded seams shall not be used. Pipe Fittings used in piping work are mainly Traps, Elbow, Reducer, Tee, Union, Coupling, Cross, Cap, Swage Nipple, Plug, Bush, Expansion Joint, Adapters, Olet (Weldolet, Sockolet, Elbowlet, Thredolet, Nipolet, Letrolet, Swepolet and Long Radius Bend and Flanges and Valve. Piping or tubing are usually (but not always) inserted into fittings to make connections. To avoid confusion, connections are conventionally assigned a gender of male or female, respectively abbreviated as "M" or "F". Welding End Fittings: There are Butt Weld, Socket Weld and Stub Weld fittings. Socket welding fittings are supplied in Pressure Class designations
of 3000, 6000, and 9000 lb non-shock rating. Socket Weld fittings should be as per ANSI B16.11. Butt-Weld fittings of Carbon Steel, Ferritic Alloy Steels and Stainless Steel up to 24” NB should be as per ANSI B16.9 or MSS-SP-43. Butt-Weld fittings of Carbon Steel, Ferritic Alloy Steels and Stainless Steel up to 26” NB and larger should be as per MSS-SP-48. The bore of Socket Weld fittings should be manufactured to suit the pipe O.D. and its thickness. Mitre Bends should be fabricated with 5 times radius of the pipe nominal diameter in case of non-availability of forged readymade Elbow on all lines up to 1.5” NB pipe. The pressure drop due to fittings is calculated by including their equivalent length in the total length of the piping system. Equivalent lengths for welded elbows and tees are included in table 2.2 of RP 14E. Stub-Weld fittings should not be used in pressure piping. Fittings of lower schedule or thickness should not be used. Threaded (Screwed) End Fittings: Forged steel screwed fittings are manufactured of 2000, 3000 and 6000 lb Ratings to ASTM A 105 and ANSI B16.11. Fitting’s threads should confirm to ANSI B2.1 unless otherwise it is specified. Any threaded joints up to 200 0C should be made with 1” wide PTFE jointing tape. Any threaded joints above 200 0C should be made with seal welded with a full strength fillet weld. Threaded fittings have screwed (threaded) ends and they screw together to connect. For fittings threads sizes, “½ to 14 NPT”, are made according to the NPT (American
Standard Pipe Taper Thread) standard. The word “taper” refers to the bottoms of the threads, which is 1/16 inch in an inch as shown in the sketch below. Fitting threads make a leak proof mechanical joint.
Because of the taper, a fitting can only screw onto a pipe a little distance before it jams. The standard represents this distance, the effective thread. The standard also represents another distance, the engagement, which is the distance the pipe can be screwed in by hand, without much effort. Various threads available in pipe and pipe fittings are as follows: (i) Right-handed Threads; (ii) Left-handed Threads. By turning it in a clockwise direction, the item turned moves away from the viewer. And it is loosened by turning anticlockwise when the item moves towards the viewer. This is known as a right-handed thread. Left-handed threads are oriented in the opposite direction. Male Threads: In male threads, the threads of the pipe are on the outside. Here, tapered pipe threads like NPT, BSPT are provides sealing without gaskets. Female Threads: In female threads, the threads are on the inside. Here too, like male threads, tapered pipe threads are used for sealing. There are Male Straight Thread and Female Straight Thread too. Applicable Codes and Standards ASTM A105: Carbon Steel Forging for Piping Components ASTM A 126 Gray Iron Castings for Valves, Flanges, and Pipe Fittings ASTM A181: Carbon Steel Forging for General Purpose Piping Components ASTM A182: Forged Alloy Steel Flanges, Fittings and Valves, and Parts for High-Temperature Service ASTM A216: Carbon Steel Castings for high temperature Service ASTM A217: Martensitic Stainless Steel and Alloy Steel Castings for pressure containing Parts ASTM A234: Wrought Carbon Steel Fittings for High Temperature Service ASTM A350: Carbon and Low-Alloy Steel Forged Piping Components Requiring Notch Toughness Testing ASTM A351: Austenitic and Austenitic-Ferritic (Duplex) Castings for Pressure Containing Parts ASTM A352: Ferritic and Martensitic Steel Castings for Pressure containing Parts suitable for Low-Temperature Service
ASTM A403:
Wrought Austenitic Stainless Steel Piping Fittings ASTM A420: Wrought Carbon Steel and Alloy Steel Fittings for LowTemperature Service ASTM A592: Low-Alloy Steel, Quenched and Tempered, Forged
Fittings and Parts for High Pressure and High Strength service ASTM A815: Wrought Ferritic, Austenitic and Martensitic Stainless Steel Piping Fittings ANSI B1.1: Unified Inch Screw Threads (UN and UNR Thread Form) ANSI B1.20.1: Pipe Threads, General Purpose (Inch) ANSI B1.20.3: Dry seal Pipe Threads (Inch) ANSI B1.20.7: House Coupling Screw Threads (Inch) ANSI B2.1: Pipe Threads ANSI B16.1: Cast Iron Flanges and Flanged Fittings, Classes 25, 125, 250, and 800 ANSI B16.3: Malleable Iron Threaded Fittings ANSI B16.4: Grey Iron Threaded fittings ANSI B16.5: Steel pipe flanges and flanged valves and fittings ANSI B16.9: Wrought Steel butt welding fittings, dimension and Tolerance ANSI B16.10: Face to face and end-to-end Dimensions of ferrous Valves ANSI B16.11: Forged steel fittings (socket- welding and threaded) ANSI B16.14: Ferrous pipe plugs, bushings, and lock nuts with pipe threads ANSI B16.15: Cast Bronze Threaded Fittings, Class 125 and 250. ANSI B16.20: Ring joint gaskets for pipe flanges ANSI B16.21: Non-metallic gaskets for pipe flanges ANSI B16.22: Wrought Copper and Copper Alloy Solder Joint Pressure Fittings ANSI B16.24: Bronze Pipe Flanges and Flanged Fittings, Classes 150 and 300 ANSI B16.25: Butt-welded flanges and fittings ANSI B16.26: Cast Copper Alloy Fittings for Flared Copper Tubes ANSI B16.28: Wrought Steel Butt welding short radius Elbows and Returns ANSI B16.31: Non-Ferrous Pipe Flanges ANSI B16.34: Flanged, Threaded and Welding End Valves ANSI B16.36: Orifice Flanges, Class 300, 600, 900, 1500, and 2500 ANSI B16.39: Malleable Iron Threaded Pipe Unions, Class 150, 250, and 300 ANSI B16.42: Ductile Iron Pie Flanges and Flanged Fittings, ANSI B16.47: Large Diameter Steel Flanges, NPS 26 through NPS 60 ANSI B18.2.1: Square Hex Bolts and Screws, Including Hex Cap Screws and Lag Screws. ANSI B18.2.2: Square and Hex Nuts (Inch series) ANSI B36.10M: Welded and Seamless Wrought Steel Pipe ANSI B36.19M: Stainless Steel Pipe ANSI B46.1: Code for Surface Texture (Surface Roughness, heaving and Lays) IS 210: Grey Iron Castings IS 554: Dimensions of Pipe Threads MSS-SP: Manufacturers Standardization Society-Standard Practices
MSS-SP-6 MSS-SP-25 MSS-SP-42 MSS SP-43 MSS SP-44 MSS SP-45 MSS SP-48 MSS SP-51 MSS-SP-52 MSS-SP-56 MSS SP-58 MSS-SP-61 MSS SP-63 MSS SP-65 MSS-SP-67 MSS-SP-68 MSS SP-69 MSS-SP-70 MSS-SP-71 MSS-SP-72
MSS SP-75 MSS-SP-78 MSS-SP-80 MSS-SP-81 MSS-SP-83 MSS-SP-85 MSS-SP-88 MSS SP-89 MSS-SP-90 MSS-SP-92 MSS SP-95 MSS SP-104 MSS-SP-108 MSS SP-114 MSS SP-119 MSS-SP-58:
Standard Finishes for contact surface for flanges Standard marking system for valves, fittings, flanges Class 150 corrosion resistant gate, globe and check valves Wrought Stainless Steel Butt welding Fittings Steel Pipeline Flanges Bypass and Drain Connections Carbon Steel Butt Welded Flanges Class 150 LW Corrosion Resistant Cast Flanges and Flanged Fittings Cast Iron Gate, Plug and Check Valves MSS-SP-53 Standard for Steel Casting for Valves, Flanges and fittings Pipe hanger supports - Material, design and manufacture Pipe Hangers and Supports - Materials, Design and Manufacturer Pressure testing of valves High Strength wrought welding Fittings High Pressure Flanges and Threaded Stubs for use with Lens Gaskets Butterfly Valves High Pressure off seat butterfly valves Pipe Hangers and Supports - Selection and Application Cast Iron Gate valves Cast iron check valves Ball Valves MSS SP-73 Brazing Joints for Wrought and Cast Copper Alloy – Solder Joint Pressure Fittings Specification for High Test Wrought Butt welding Fittings Cast iron plug valves Bronze gate, globe and check valves Stainless steel bonnet less knife gate valves Pipe unions Cast iron globe valves Diaphragm valves Pipe Hangers and Supports - Fabrication and Installation Practices Pipe hangers and supports - guidelines on terminology MSS valves user guide Swage (d) Nipples and Bull Plugs Wrought Copper Solder Joint Pressure Fittings MSS SP-106 Cast Copper Alloy Flanges and Flanged Fittings, Resilient seated eccentric CI plug valves Corrosion Resistant Pipe Fittings Threaded and Socket Welding Balled End Socket Welding Fittings, Stainless Steel and Copper-Nickel Material and Design of Pipe Hangers and Supports
MSS SP-69: ASTM A47:
Selection and application of pipe hangers and supports Ferritic Malleable Iron Castings ASTM A278: Grey Iron Castings for pressure containing parts for Temperature up to 650`F
ALUMINIUM
AND
ALUMINIUM ALLOY
ASTM SB-548: Ultrasonic Examination of Aluminium-Alloy Plate for Pressure Vessels COPPER & COPPER ALLOYS ASTM SB-61: Steam Valve Bronze Casting ASTM SB-369: Copper-Nickel Alloy Castings ASTM SB-824: General Requirements for Copper-Alloy Castings A ASTM SB-858M: Determination of susceptibility to stress corrosion cracking in Copper-Alloys using an Ammonia Vapour Test NICKEL & NICKEL ALLOYS ASTM SB-366: Factory-Made Wrought Nickel and Nickel-Alloy Fittings ASTM SB-444: Nickel-Chromium-Molybdenum-Columbium Alloy (UNS N06625) Pipe and Tube ASTM SB-494: Nickel and Nickel-Alloy Castings ASTM SB-494M: Nickel and Nickel-Alloy Castings TITANIUM & TITANIUM ALLOYS ASTM SB-363: Seamless and Welded Unalloyed Titanium and Titanium Alloy Welding Fittings. ASTM SB-367: Titanium and Titanium Alloy Castings ASTM SB-381: Titanium and Titanium Alloy Forging ZIRCONIUM & ZIRCONIUM ALLOYS ASTM SB-493: Zirconium and Zirconium Alloy Forging A21.14: Ductile Iron Fittings, 3 Inch through 24 Inch, for Gas Types of Pipe Fittings: Followings are the different types of Pipe Fittings being used in Industries:
Adapter: Adapter is needed for changing from one type of end condition to another. Adapters extend or terminate pipe runs. They are used to connect dissimilar pipes. These fittings are somewhat similar to pipe couplings, with the difference that they connect pipe of different types. Pipe adapters may have either male or female end or the opposite gender on the each end, which needs to be welded or screwed onto a smaller pipe. Bush: Bush is threaded on Hexagonal
both the inside and outside Bush and used for joining pipes with different diameters together Cap: Cap covers the end of a pipe. A cap is used like plug, except that the pipe caps screws or attaches on the male thread of a pipe or a nipple. A cap may have a Butt-weld weld end, socket weld Cap (But-Weld) end or a female threaded end and the other end closed off. Industrial caps can be round, square, rectangular, U-shaped, I-shaped and have a round hand grip or a flat hand grip. Caps act as protective device and are designed to protect pipe ends of various shapes. Coupling: A coupling Equal connects two pipes to each Coupling other. Couplings help to (Socketextend or terminate pipe runs Weld) and also used to change pipe Equal Coupling (Screwed) size. Couplings extend a run by joining two lengths of pipe. They are known as reduced coupling if they are used to connect pipes of different sizes. Cross: Cross is a 4-way Cross fitting. If a branch line (Socketpasses completely through a Weld) tee, the fitting becomes a Cross cross. A cross has one inlet (Screwed) and three outlets, or vice versa. They are socket weld ends or female threaded ends. Cross fittings can generate a huge amount of stress on pipe as temperature changes, because they are at the centre of four connection points. Crosses are common in fire sprinkler systems. Elbow: An elbow is 900 installed between two Reducing
lengths of pipe or tubing to allow a change of direction of flow at a 90° or 45° or 22.5°. The ends are Butt Welding, Threaded (Screwed), or Socket Welding. When the two ends differ in size, it is called a reducing elbow or reducer elbow. 90 Degree Elbow changes the direction by 90°. 45 Degree Elbow changes the direction by 45°. A 90 degree elbow is also called a "90 bend" or "90 ell". A 45 degree elbow is also called a "45 bend" or "45 ell". Elbows are various features as below: Long Radius (LR) Elbows: Long Radius elbows have a Radius of 1.5 times the pipe diameter or the NPS and are used when sufficient space is available and flow is more critical. Long elbows are typically used in lowpressure gravity-fed systems and other applications where low turbulence and minimum deposition of entrained solids are of concern. Short Radius (SR) Elbows: Short Radius elbows have a Centre-to-Face dimension of 1.0 times the pipe diameter or the Nominal Pipe Size (NPS) and are typically used in tight areas where clearances are an issue. Short elbows are widely available, and are typically used in pressurized systems. Expansion Joints:
Elbow (ButWeld) 450 Elbow (ButWeld) 900 Elbow (ButWeld) 900 Reducing Elbow (Screwed) 900 Elbow (Screwed) 900 MaleFemale Elbow (Screwed) 900 MaleMale Elbow (Screwed)
Expansion joints
connect two pipes and allow movement due to service load, shock, or thermal cycles. They are made of steel and feature a bellows-style construction. Convolutions permit misalignment, movement or isolation of the components that are joined together. Expansion joints are a flanged end or welded end to attach to components. Expansion joints are designed for vacuum or process-gas systems also in which vacuum flanges and fittings connect runs of pipes or tubes to other sections of pipes or tubes, as well as fittings. Nipple: Nipple is a short stub of pipe which has a male pipe thread at each end for connecting two other fittings. Nipples are used for connecting pipe, hoses, and valves. It is a connector or a coupling threaded on both ends. Olets: Whenever branch connections are required in size where reducing tees are not available and/or when the branch connections are of smaller size as compared to header size, Olets are generally used. The following are few configurations of Olet connections: Weld Olet; Sock Olet and Elbo Olet. Plug: A plug closes off the end of a pipe. It is similar to a cap but it fits inside the fitting it is mated to. In a threaded pipe system, plugs have male threads. Plugs are designed to insert into the end of pipe to dead-end the
Reducing Nipple (SocketWeld) Swage Nipple
Weldolet Sockolet
Plug
flow. Reducer: A pipe reducer changes the size of the pipe and fulfils the hydraulic requirements so to adjust with the existing piping. They provide a highly reliable, sturdy and tight integral line system and these types of pipe fittings remain unaffected by shock, vibration or thermal distortion. Reducer connects two pipes of different sizes. There are two types of reducer, (i) Concentric and (ii) Eccentric. Concentric Reducers are used to join pipe sections on the same axis. They provide an in-line conical transition between pressurized pipes of differing diameters. The pipe flow is affected by the inside diameter conical transition configuration which can be axially moved and externally reconfigured to provide for more economical reducer fittings. When transporting between flanges or pipes of different ratings and wear protection is necessary, concentric reducers are ideal. The concentric reducer eliminates noise pollution. Eccentric reducer is applied only when it is required to maintain the pipe level either on top and bottom of the pipe. Eccentric reducer maintains the air force direction to avoid trapping of air inside the pipe and is very useful for pump suction line. They are useful in services where cavitations are present. An eccentric reducer is designed with two ends of different sizes and different centres so that when they are joined, the pipes are not in line with each other, but the two pieces of pipes can be installed so as to provide optimum drainage of the line. The eccentric pipe reducers allow simple connection of different sized pipes. The reducer must be installed with straight side up so that it can prevent
Concentric Reducer (ButWeld)
Eccentric Reducer Weld)
(But-
Sectional View of Reducer
trapping air at the pump suction.
Tee: A tee is the most common pipe fitting. It is used to either combine or split a fluid flow. It is a Tshaped fitting having two outlets, at 90° to the connection to the main line. It is a short piece of pipe with a lateral outlet. A tee is used for connecting pipes of different diameters or for changing the direction of pipe runs for distribution of the flow. They are categorized as, Equal Tee and Unequal Tee. When the size of the branch is same as header pipes, it is equal tee and when the branch size is less than that of header size, it is reduced tee. Most of the tees are having the same inlet and outlet sizes.
Equal Tee (ButWeld)
Reducing Tee (ButWeld) Reducing Tee (Screwed)
Trap: Trap regularly inject water into traps so that "water seals" are maintained, as necessary to keep steam or sewer gases out of system. The trap must be installed in a readily available place for easy access for adjustments, replacement, and repair. Strictly speaking, a trap is a specialized valve. Because of this dual connection, the design usually is certified to resist accidental backflow of contaminated water. Union: A union is similar to a coupling,
except it is designed to allow quick and convenient disconnection of pipes for maintenance or fixture replacement. A union provides a simple transition, allowing easy connection or disconnection at any future time. A standard union pipe is made in three parts consisting of a nut, a female end, and a male end. When the female and male ends are joined, the nuts then provide the necessary pressure to seal the joint. Since the mating ends of the union are interchangeable, changing of a valve or other device can be achieved with a minimum loss of time. Pipe unions are essentially a type of flange connector. In addition to a standard union, there exist dielectric unions which are used to separate dissimilar metals (such as copper and galvanized steel) to avoid the damaging effects of galvanic corrosion. When two dissimilar metals are in contact with an electrically conductive solution (even tap water is conductive), they will form a battery and generate a voltage by electrolysis. When the two metals are in direct contact with each other, the electric current from one metal to the other will cause a movement of ions from one to the other, dissolving one metal and depositing it on the other. A dielectric union breaks the electric current path with a plastic liner between two halves of the union, thus limiting galvanic corrosion.
(Socket-Weld)
(Screwed)
Male-Female (Screwed)
Parts of Union
Wye Tee: It is basically a Tee but in the shape of a wye and is used to create branch lines. It is a type of Tee which has the side inlet pipe entering at a 45° angle, or an angle other than 90 degrees. A standard wye is a "Y" shaped fitting which allows one pipe to be joined to Standard another at a 45 degree angle. Wyes are Wye similar to tees except that the branch line is angled to reduce friction and turbulence that could hamper the flow. PVDF Corrosive Waste Piping Systems utilize wye fittings. Pipe wyes are used to allow one pipe to join another pipe at some degree or angle. As the name suggests, the pipe wyes are Y-shaped pipe fitting devices. Pipe wyes are similar to pipe tees. The only difference is in that the branch line is angled to reduce friction which could hamper the flow.
Pipe
5.3
Flanges
Common methods for the joining of the pipe include welding, flanged and threaded. A pipe flange is disc, collar or ring that attaches to pipe with the purpose of connecting the pipes to pipes or a pipe to any fitting or valve or equipment nozzles. Flanges are also used for the purpose of dismantling piping systems, temporary or mobile installations, transitions between dissimilar materials, and connections in environments not conducive to solvent cementing. Pipe flanges are usually welded or screwed to the pipe end and are connected with bolts to other parts. A gasket is inserted between the two mating flanges to provide a tighter seal. Flanges are relatively simple mechanical connectors that have been used successfully for high-pressure piping applications. They are well understood, reliable, costeffective, and readily available from a wide range of suppliers. This is an important feature for systems that experience pipe-walking or lateral buckling from temperature and pressure variations. Flanges can be designed to meet a wide range of application requirements such as high-temperature and corrosion resistance. Pipe flanges have flush or flat surfaces that are perpendicular to the pipe to which they attach. Two of these surfaces are mechanically joined via bolts, collars or welds. Ease of assembly is a qualitative measure of the efficiency of the assembly and disassembly process and the ease of set up and take down time can be very important. Durability is the strength or toughness of a pipe flange under stress or pressure. Pipe flange products generally have a pressure rating that defines the maximum pressure the flange is designed to hold. The pressure classes have differing pressure and temperature ratings for different materials. The flange faces are also made to standardized dimensions and are typically "flat face", "raised face", "tongue and groove", or "ring joint" styles. In piping assembly, few joints are to be made, necessarily, with flanges for the following reasons: a) For maintenance of the pipe as and when required. b) For installation of the valves to control the flow of the fluid passing through the pipe. c) For installation of the instruments to monitor the total system during operation. d) Other miscellaneous work like maintenance. Applicable Manufacturing Standards: Pipe flanges and flanged fittings are made from forged materials and have machined surfaces and nominal pipe sizes (NPS) from ½" to 24" as per ASME B16.5 for most liquid process piping materials. Pipe flanges made to standard ASME B16.47 covers NPS from 26" to 60". Each Specification delineates flanges into pressure classes of 150, 300, 400, 600, 900, 1500 and 2500 psi for B16.5; B16.47 delineates its flanges into pressure classes 75, 150, 300, 400, 600, 900. Materials for flanges are usually under ASME designation: SA-105 (Specification for Carbon Steel Forgings for Piping Applications), SA-266 (Specification for Carbon Steel Forgings for Pressure Vessel Components), or SA-182 (Specification for Forged or Rolled Alloy-Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service). The selection of “End Facing” and “Face Finishing” of the Flanges, Blind Flanges or Spacers, 2” dia. and above should be done as per requirements of standards. Bevel end finish for Weld neck flange is to be as per ANSI B16.5.Screwed flanges and fittings should be threaded tapered as per ANSI B2.1 up to 1.5” Nom. Dia. And as per IS 554 for 2” to 6” Nom. Dia. All austenitic stainless steel flanges, blind flanges, Drip Rings, Spectacle Blinds (Fig. 8 flange) and fittings should be solution annealed condition and should be inter granular corrosion tested as per following requirements, ASTM A262, practice BAcceptance criteria of 60 mils/year (max.). ASTM A262, practice E- Acceptance criteria “no crack observed with 20 X magnification” and “microscopic structure observed from 250 X magnification”.
In addition, there are many standards as below: ASTM A350 LF1, LF2 & LF6 (Low Temperature). ASTM A350 LF3 (Low Temperature: 3 1/2% Nickel) ASTM A707 through L3 Class 3 (Low Temperature) ASTM A694 F42 through F65 (High Strength) Plates IS 226: Specification for structural Steel s IS 2062: Specification for Structural Steels ASTM A6: General Requirements for Rolled Steel Plates for Structural ASTM A20: General Requirements for Steel Plates for Pressure Vessels ASTM A36: Carbon Structural Steel ASTM A202: Pressure Vessel Plates, Alloy Steel, and ChromiumManganese-Silicon ASTM A203: Pressure vessel Plates, Alloy Steel, Nickel ASTM A204: Pressure vessel Plates Alloy steel, Molybdenum ASTM A240: Heat-Resisting Stainless steel Plate, sheets and strips for pressure vessel ASTM A263: Corrosion-Resisting Chromium steel clad plates, sheet and strip ASTM A264: Chromium-Nickel Stainless steel clad plate, sheet and Strip ASTM A265: Nickel and Nickel-Base Alloy clad steel plate ASTM A283: Low and Intermediate Tensile Strength Carbon Steel Plates ASTM A285: CS Pressure Vessel Plates, Low and Intermediate Tensile Strength ASTM A515: CS Plates for Intermediate and High-Temperature Service ASTM A516: CS Pressure vessel Plates for Moderate and LowTemperature Service ASTM A517: AS High Strength, Quenched and Tempered, Pressure Vessel Plates ASTM A537: Carbon-Manganese-Silicon Steel, Pressure Vessel plates ASTM SB 168: Nickel Chromium Iron Alloy (UNS) Plate, Sheet and Strip ASTM SB-127: Nickel-Copper Alloy (UNS N04400) Plate, Sheet and Strip ASTM SB-171: Copper-Alloy Plate and Sheet for Condensers and Heat Exchangers ASTM SB-209: Aluminium and Aluminium –Alloy Sheet and Plates ASTM SB-265:Titanium and Titanium-Alloy Strip, Sheet and Plates ASTM SB-548:Ultrasonic Examination of Aluminium-Alloy Plate for Pressure Vessels ASTM SB-551:Zirconium and Zirconium Alloy Strips, Sheets and plates ASTM SB-96: Copper-Silicon Alloy Plate, Sheet, Strip and Rolled Bar
STRUCTURAL STEEL IS 226: IS 2062:
Specification for structural Steel s Specification for Structural Steels
ASTM A6: General Requirements for Rolled Steel Plates for Structural use ASTM A36: Carbon Structural Steel ASTM A283: Low and Intermediate Tensile Strength Carbon Steel Plates Types of Pipe Flanges: There are many types of flanges based on their design and specifications. Some of these types are as given in Table below in sizes 1/2" to 198". Weld Neck Flanges
Slip On Flanges
Lap Joint Flanges Large Flanges
Threaded Flanges Diameter Orifice Flanges
Socket Weld Flanges Blind Flanges Reducing Flanges
Selection of Flanges: The comparison of flange types by pressure capacity, suitable pipe sizes, applications or advantages are as below: Type Blind
Pressure Pipe Capacity Sizes Very high All
Lap joint
Low
All
Slip-on
Low
All
Socket weld
High
Small
Threaded Low Welding neck High
Small All
Blind
Very high All
Applications / Advantages Closing pipes, flow pressure testing Systems requiring frequent disassembly Low installation cost, simple assembly Smooth bore for better fluid flow Attachment without welding High pressures and extreme temperatures Closing pipes, flow pressure testing
Types of Flanges with sketch Weld Neck (WN) Flanges: Weld neck flanges have a long tapered hub. Weld neck flanges attach to the pipe by welding the pipe to the neck of the Flange. The tapered hub transfers stress from the flange to the pipe itself and provides strength reinforcement that counteracts dishing and reduces high stress concentration at the base of the hub of the weld neck flanges. The
weld neck flange is also called as the "high hub" Flange. It is expensive because of the design. Weld neck pipe flanges are often used for high pressure piping. The inside diameter of a weld neck flange is machined to match the inside diameter of the pipe. Weld neck flanges have the same thickness as the pipe and have a slight taper so they are perfect for use in high pressure conditions. Weld Neck flanges are used in extremely high pressure or high temperature conditions. Weld Neck flanges range from 1/2" thru 96". Weld neck flanges are provided with a raised face, flat face, or RTJ facing. The raised face is of weld neck pipe flanges have the standard height of 1/16" up to 400# and 1/4" for 400# and above. Weld neck flanges are made of all steel material grades, including carbon steel, stainless steel and alloy steel. Weld neck pipe flanges conform to ANSI B16.5, ASME B16.47 Series "A", ASME B16.47 Series "B", and Pressure Vessel code and as per customer requirements Slip-On Flanges: Slip-On flanges actually slip over the pipe. Slip-On flanges have a low hub because the pipe slips into the flange prior to welding. It is welded both inside and out to the pipe to provide sufficient strength and prevent leakage. Slip-on flanges are bored slightly larger than the O.D. of the pipe. This allows the flange to slide over the pipe but to still have a somewhat snug fit. Slip-on pipe flanges are secured to the pipe with a fillet weld to the pipe at the outside and the inside of the slip-on flanges. These flanges are provided with a ring or a hub. Ring type flanges and hub type flanges are both
Fig: Sectional View of Weld Neck Flange.
Fig: Sectional View of Slip On Flange
considered slip on flanges because they both slip over the pipe. They are preferred over welding neck flanges by many users due to their lower initial cost. Slip-on flanges range from 1/2" thru 96". Slip-on flanges are made of carbon steel material grades, including carbon steel, stainless steel and alloy steel and conform to AWWA, ANSI, and Pressure Vessel and ASME codes. Slip on pipe flanges are provided with a raised or flat face. The raised faces have the standard height is 1/16" for slip on flanges under 400 and the raised face height is ¼’ for 400# and above rating flanges. Socket Weld Flanges: Socket Weld flanges are attached to pipe by inserting the pipe into the socket end of flanges and applying fillet weld around the top (outside). These flanges are used on smaller sizes of high pressure pipes. Socket weld flanges are ideal for small-size, high-pressure piping. Their fabrication is similar to that of slip-on flanges, but the internal pocket design allows for a smooth bore and better fluid flow. If it is Fig: Sectional internally welded, it has fatigue View of Socket strength 50% greater than double Weld Flange. welded slip-on flanges. A restriction is built into the bottom of the bore which sets as a shoulder for the pipe to rest on. This allows for a smooth bore and better flow of the fluid or gas inside of the pipe. Socket Weld pipe flanges are provided with a raised face, flat face, or RTJ facing. The raised faces have the standard height is 1/16" for slip on flanges under 400 and the raised face height is ¼’ for 400# and above rating flanges. Slip on pipe flanges are made of all steel material grades, including carbon steel, stainless steel and alloy steel and
conform to AWWA, ANSI, Pressure Vessel and ASME codes. Lap Joint Flanges: Lap Joint Pipe Flanges slide over the pipe and are used with Stub End Fittings. Lap joint flanges are inserted into the inside of the pipe flanges. The advantage of lap joint flanges is that they have superb manoeuvrability. Lap joint flanges are able to swivel even after the welds have been completed, making them perfect for bolt alignment. Lap joint Sectional flanges are most commonly used on Fig: applications that require frequent View of Lap Joint dismantling of joint for inspection or Flange. cleaning and maintenance. A pipe is welded to the Stub End and the Lap Joint Flange is free to rotate around the stub end. The benefit of this is that there will not be any issues with bolt hole alignment. Normally, a lap joint flange and a lap joint stub end are mated together in an assembly system. Lap joint flanges are used on piping fitted with lapped pipe or with lap joint stub ends. They are similar to slip-on flanges, but have a curved radius at the bore and face to accommodate a lap joint stub end. Lap Joint Flanges are manufactured in all steel material grades, including carbon steel, stainless steel and alloy steel. Threaded (Screwed) Flanges: Threaded flanges are attached to the pipe with the help of threads and without welding to the pipe. Threaded Flanges are similar to slip-on flanges except the bore of the flange has tapered threads. They are threaded in the bore to match external threading on a pipe and are tapered to create a seal between the flange and the pipe. Threaded flanges are used with pipes that have external threads. The benefit
of these flanges is that it can be Fig: Sectional attached without welding. Threaded View of Threaded flanges are often used for small Flange. diameter, high pressure requirements. Threaded pipe flanges are provided with a raised face or flat face and are manufactured in all steel material grades, including carbon steel, stainless steel and alloy steel. It is used in low pressure services at ordinary atmospheric temperatures and in highly explosive areas where welding create a hazard. Seal welds can also be done along with threaded end for added reinforcement and sealing. They are avoided in applications with large loads and high torques. Blind Flanges: Blind flanges are round plates with no centre hole and have no bore. Blind Flanges are used to seal or close off the end of a piping system or pressure vessel openings to prevent flow and are also used for pressure testing of the pipe or vessel and valves and permits easy access to the interior of a pipe line or vessel once it has Sectional been sealed and must be reopened. Fig: Blind flanges are manufactured in all View of Blind steel material grades, including carbon Flange. steel, stainless steel and alloy steel and specifications and sizes. Blind flanges are provided with a raised face, flat face, or RTJ facing. When a raised face is necessary for blind pipe flanges, the standard height is 1/16" for blind pipe flanges up to 400# and 1/4" for 400# and above. Blind pipe flanges conform to ANSI B16.5, ASME B16.47 Series "A", ASME B16.47 Series "B" and Pressure Vessel. Spectacle Blind Flange: A spectacle flange is made of two metal discs
attached in the middle by a small piece of steel plate and look like a pair of reading glasses, or spectacles. Spectacle flanges are most commonly used on piping systems, whose flow is Typical regularly to be stopped and which need Fig: Blind to be separated regularly. One end of Spectacle the spectacle flange is round plate, Flange. while the other end has a hole in the centre. The spectacle flange can be placed with either the solid plate or hollow plate within the pipe system, thereby closing or opening the flow respectively. The Advantages of Spectacle Flanges are that they require no welding for installation, and have a wide range of pressure tolerances. Reducing Flange: Reducing flanges are used in place of standard flanges to allow for a change in pipe size. Reducing flanges are used on piping that requires the fitting of different sized pipes. The flange consists of one specified diameter with a smaller Sectional diameter bore size. Except for the bore Fig: and hub dimensions, a reducing flange View of Reducing has dimensions of the standard pipe Flange. flanges size, and is considered an economical means to make a pipe size transition. There are several types of reducing flanges including weld, slipon and threaded reducing flanges. The reducing flanges are highly economical way to make transitions between pipes of different sizes. Orifice Flanges: Orifice flanges are designed to incorporate special functions, such as, orifice mounting. Orifice flanges are used in place of standard flanges to allow an orifice meter to be installed on the flange. Orifice plate carriers are designed into the flanges for fitting meter
connections. These meters are used to measure the flow rate through the system at that point. Flange Dimensional Tolerances: The Flange Dimensional Tolerance listed below includes those of the ANSI B 16.5 and additional Manufacturing Tolerance covered by this standard.
Table: Tolerances of Flanges Outside Diameter of Flanges When O.D. ± 1/16” is 24” or less When O.D. ± 1/8” is over 24” 10” and + 1/32” – 0” Inside Diameter Slip-On and Lap Smaller 12” to 24” + 1/16” – 0” Joint flanges 26” and + 2/32” – 0” Larger 10” and ± 1/32” Weld Smaller Neck, 12” to 18” ± 1/16” Long Weld 20” and + 1/8” – 1/16” Neck - Larger flanges and + 1/32” – 0” Diameter of Counter bore 10” Smaller (Threaded) 18” and + 1/8” – 0” Flange Thickness Smaller 20” and + 3/16” – 0” Larger 5” and + 3/32 – Hub - O.D. at Weld Smaller 1/32” Point of Weld Neck 6” and + 5/32” – Larger 1/32” Hub (Thickness Not less than 87.5% of the nominal at Point of thickness of the pipe to which flange is to be attached. Weld) and + 3/32 – Outside Diameter of Neck: 10” Smaller 1/32” Long Weld Neck-flanges
12” and Larger Special Bolt Hole Bolt Drilling Circle Regular Bolt Hole Special Spacing Regular Eccentricity of Bolt Circle and Facing w.r.t. Bore Overall Height: Threaded, All Size Slip-On, Lap Joint and Blind flanges and Overall Height: Weld Neck 10” and long Weld Neck - Smaller 12” and Flanges Larger
+ 3/32” – 1/16” ± 1/32” ± 1/16” ± 1/64” ± 1/32” 1/32” Max. ± 1/16”
± 1/16” ± 1/8”
Blind flanges & Blanks: All blind flanges and blanks shall be designed as per boiler & pressure vessel code section VIII, Division I, UG – 34 and in accordance with following equations: tm = t + c
3P tm = dg
+
c 16 SE
Where, dg = Inside diameter of gasket for raised face or flat face flange or the Gasket pitch diameter for ring joint and fully retained gasket Flanges. E, P, S & c = as defined above.
Materials of Flanges: Pipe flanges can be made from a number of different materials depending on the piping material and the requirements of the application. Selection depends on factors such as environmental corrosion, operating temperature, flow pressure, and economy. Some of the most common materials include carbon steel, alloy steel, stainless steel, cast iron, copper, and PVC. Alloy steel: Alloy steel is steel alloyed with one or more elements which enhance or change the steel's properties. Common alloys include manganese, vanadium, nickel, molybdenum, and chromium. Alloy steels are differentiated based on standard grades. For specific information on individual types of alloying elements, please visit the Metals and Alloys section on Global Specifications. Aluminium: Aluminium is a malleable, ductile, low density metal with medium strength. It has better corrosion resistance than typical carbon and alloy steels. It is most useful in constructing flanges requiring both strength and low weight. For more information on aluminium, please visit the Aluminium and Aluminium Alloys area on Global Specifications. Brass: Brass is an alloy of copper and zinc, often with additional elements such as lead or tin. It is characterized by good strength, excellent high temperature ductility, reasonable cold ductility, good conductivity, excellent corrosion resistance, and good bearing properties. For more information on
brass and other copper alloys, please visit the Copper, Brass, and Bronze Alloys area on Global Specifications. Carbon steel: Carbon steel is steel alloyed primarily with carbon. It has a high hardness and strength which increases with carbon content, but lowers ductility and melting point. For more information on carbon and alloy steels, please visit the Carbon Steels and Alloy Steels area on Global Specifications. Cast iron: Cast iron is iron alloyed with carbon, silicon, and a number of other alloying elements. Silicon forces carbon out of the iron, forming a black graphite layer on the exterior of the metal. Cast irons have good fluidity, cast ability, machine ability, and wear resistance but tend to be somewhat brittle with low melting points. For more information on cast irons, please visit the Cast Irons area on Global Specifications. PVC: PVC or polyvinyl chloride is a thermoplastic polymer that is inexpensive, durable, and easy to assemble. It is resistant to both chemical and biological corrosion. By adding plasticizers it can be made softer and more flexible. Stainless steel: Stainless steel is steel alloyed with chromium in amounts above 10%. Chromium enables stainless steel to have a much higher corrosion resistance than carbon steel, which rusts readily from air and moisture exposure. This makes stainless steel better suited for corrosive applications that also require high strength. For more information on stainless steel alloys, please visit the Stainless Steel Alloys area on Global Specifications. Method of Flange Attachment: Method of attachment is a distinguishing feature of the flanges. Typically, flanges are attached to pipes via welding or threading. Weld Joint: Welding joint joins the flanges to the pipe by melting the work pieces and filler material s together and then solidifying the same. Welding is the most effective method of flange connection and so most pipe flanges are designed to be welded to pipes. Thread Joint: Thread Joint joins the flanges to the pipe by use of threads. This is applied to flanges and pipes to allow the connections to be screwed together in a manner similar to nuts or bolts. Physical Specifications: Physical specifications for flanges include dimensions and design shapes so that a flange must fit the pipe or equipment for which it is designed. Physical dimensions should be specified in order to size flanges correctly. Outside diameter (OD): Outside diameter (OD) is the distance between two opposing edges of a flange's face. Thickness: Thickness refers to the thickness of the attaching outer rim, and does not include the part of the flange that holds the pipe. Bolt circle diameter: Bolt circle diameter is the length from the centre of a bolt hole to the centre of the opposing hole. Flange size: Flange size is corresponding pipe size, generally made according to accepted standards. It is usually specified by two non-dimensional numbers, nominal pipe size (NPS) and schedule (SCH). Nominal bore size is the inner diameter of the flange connector. When manufacturing and ordering any type of pipe connector, it is important to match the bore size of the piece with the bore size of the mating pipe. ANSI B16.5 Class 150 to 600 Forged Flanges
Weld Neck Forged Flange
Threaded Forged Flange
Lap Joint Forged Flange
Socket Weld Forged Flange
Blind Forged Flange Slip On Forged Flange
Flanges Facings: Flange faces are manufactured to a large number of custom shapes based on design requirements. Some examples include: Flat, Raised face (RF), Ring type joint (RTJ) and O-ring groove as shown in the Sketches below:
5.4
Valves
Valves are used to isolate equipment and piping systems, regulate flow, prevent backflow, and regulate and relieve pressure. A valve regulates direct or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically pipe fittings, but are usually discussed as a separate category. Valves may be operated manually, either by a handle, lever or pedal or automatic by changes in pressure, temperature or flow. These changes may act upon a diaphragm or a piston which in turn activates the automatic valve. More complex control systems using valves requiring automatic control based on an external input (i.e., regulating flow through a pipe to a changing set point) require an actuator. An actuator will stroke the valve depending on its input and set-up, allowing the valve to be positioned accurately, and allowing control over a variety of requirements. Applicable Codes: API (American Petroleum Institute): API 6D: Standards for steel Gate, Plug, Ball and Check valves API 66: Specification for Gate and plug Valves for refinery API 526: Flanged Steel Pressure-Relief Valves API 594: Wafer and Wafer-Lug Check Valve API 599: Metal plug Valves- Flanged and Welding Ends API 600: Steel Gate Valves- Flanged and Butt welding Ends, Bolted and Pressure Seal Bonnets API 602: Compact Steel Gate Valves- Flanged, Threaded, Welding and Extended Body Ends API 603: Cast Iron Corrosion-Resistance Flanged-End Gate Valves, Class 150 API 608: Metal Ball Valves- Flanged, Threaded, and Welding Ends API 609: Lug and Wafer Type Butterfly Valves API RP526: Flanged Steel Safety Relief Valves. AWWA (American Water Works Association): AWWA C500: Gate Valves for Water and sewage system AWWA C504: Rubber Seated Butterfly Valves AWWA C507: Ball Valves 6" to 48" AWWA C508: Swing Check Valves 2" to 24" AWWA C509: Resilient Seated Gate Valves for water and sewage AWWA C510: Cast Iron Sluice Gate Valves
VALVE TYPES Valves are of different types like, Ball Valve, Gate Valve, Plug Valve, Butterfly Valve, Globe Valve, Diaphragm Valve, Needle Valve, and Check Valve, Pressure Safety Valve and Control Valve. Brief, discussions of the advantages, disadvantages, and design features for each type of valve are given below. (i) Ball Valve: Ball Valve has a spherical disc (ball) with a hole/port in the centre to control the flow through it. When the port of the valve is in line with both ends of pipe, flow will occur. When the hole is perpendicular to the axis of the pipe, the valve is closed and flow is blocked. The handle or lever
is in line with the port position indicates the valve's position. Ball valves are durable and usually work to achieve perfect shutoff even after years of use. They are therefore an excellent choice for shutoff applications and are often preferred to globe valves and gate valves for the purpose. Ball valve’s supporting pressures is up to 1000 bars and temperatures up to 482°F (250°C). Sizes typically range from 0.5 to 12 inches. They are easy to repair and operate. The body of ball valves is made of steel and ball is often chrome plated to make it more durable. Ball Valve is ideal for quick shut-off, or on/off control without pressure drop by a 90° turn as compared to multiple turns required on most manual valves. Ball valves are not suitable for throttling because, the partially open position sealing surfaces on the exterior of the ball is exposed to abrasion by process fluids. In critical service, consideration should be given to purchasing ball valves with lubrication fittings for the ball seats, as well as for the stem, since lubrication is sometimes necessary to prevent minor leaks or reduce operating torque. They are sometimes preferred to globe valves and gate valves. Although, ball valves cannot offer the fine control that may be required in throttling applications but are still sometimes used for this purpose. Ball valves have certain characteristics which make them superior to other valves, such as positive shut off; quick in action; no lubrication required; visual on/off indication; compact design; longer life; corrosion resistant; low pressure drop and simplicity. They are used in situations where tight shut-off is required; They are wide duty pipe valves; They are able to transfer liquids with suspended solids (slurries), gases, liquids; They provide superior ease of operation; They can maintain and regulate high volume, high pressure and high temperature flow; The ball valve body design permits inspection as well as repair of seats and seals without removing the valves’ body from the line; Fire safe ball valves provide effective shut-off during or following a fire or when exposed to excessive temperatures; Full port Ball valves are used in gas and oil pipelines where pigging is required. A) Types of Ball Valves on the basis of Body Styles: Ball valves are single body, three piece body, split body, top entry, or welded type. The difference is based on how the pieces of the valve, specially the casing that contains the ball itself, are assembled. The valve operation is the same in each case. B) Types of Ball Valves on the basis of Bore of the Ball: Ball valves are (i) Full Port or Full Bore Ball Valve: Full Port or more commonly known full bore ball valve, which has an over-sized ball so that the hole in the ball is the same size as the pipeline resulting in lower friction loss. Flow is unrestricted but the valve is larger and more expensive so this is only used where free flow is required, such as, in pipelines which require pigging. (ii) Reduced Port (Reduced Bore) Ball Valve: Reduced Port Ball Valve has either a 'v' shaped ball or a 'v' shaped seat. This allows the orifice to be opened and closed in a more controlled manner with a closer to linear flow characteristic. When the valve is in the closed position and opening is commenced the small end of the 'v' is opened first allowing stable flow control during this stage. This requires more robust body construction due to higher velocities of the fluids, which might damage a standard valve. Reduced Port or more commonly known reduced bore ball valves, flow through the valve is one pipe size smaller than the pipe size resulting in flow area being smaller than pipe. As the flow discharge remains constant and is equal to area of flow, area x velocity, A1V1 = A2V2, where ‘A’ is area and ‘V’ is the velocity, which increases with reduced area of flow. (iii) Trunion Ball Valve: Trunion Ball Valve has additional mechanical anchoring of the ball at the top and the bottom, suitable for larger and higher pressure valves. (iv) Cavity Filler Ball Valve: Many industries encounter problem with residues in the ball valve. Where the fluid is meant for human consumption, residues may also be
health hazard, and when where the fluid changes from time to time contamination of one fluid with another may occur. Residues arise because in the half open position of the ball valve a gap is created between the ball bore and the body in which fluid can be trapped. To avoid the fluid getting into this cavity, the cavity has to be plugged, which can be done by extending the seats in such a manner that it is always in contact with the ball. This type of ball valve is known as Cavity Filler Ball Valve. (v) Vport Ball Valve: One of the most popular flow controlling members of the V-port ball valve is a Vport ball. A V-port ball valve utilizes a partial sphere that has a V- shaped notch in it. This notch permits a wide range of service and produces an equal percentage flow characteristic. The straightforward flow design produces very little pressure drop, and the valve is suited to the control of erosive and viscous fluids or other services that have entrained solids or fibres. The V-port ball remains in contact with the seal, which produces a shearing effect as the ball closes, thus minimizing clogging. (vi) Three-way and four-way Ball Valve: Three-way ball valves with 3 ways have an Lor T-shaped hole through the middle. It is easy to see that a T valve can connect any pair of ports, or all three, together, but the 45 degree position which might disconnect all three leaves no margin for error. The L valve can connect the centre port to either side port, or disconnect all three, but it cannot connect the side ports together. (v) Four-way Ball Valve: Four-way ball valves with 4 ways have the inlet way often being orthogonal to the plane of the outlets. The operation is performed by rotating a single lever four-way valve. The 4-way ball valve has two L-shaped ports in the ball that do not interconnect, sometimes referred to as a "X" port. C) Types of ball valves on the basis of Bore of the Seal: Ball Valves are available in both (i) floating ball and (ii) Trunion-mounted designs. (i) Floating Ball Valve: Floating Ball Valves develop high operating torque in high-pressure services or large diameters but tend to provide a better seal. (ii) Trunion mounted Ball Valve: Trunion mounted ball valves turn more easily but may not seal well. Thus, a trade-off decision is required to select the proper type for each application.
Fig: Cut view of a Fig: Cut view of another Fig: Sectional Ball Valve type of Ball Valve. View of a Ball Valve (ii) Gate valve: The gate valve is one of the most common valves used in liquid piping to turn on and shut off the flow, isolating either a piece of equipment or a pipeline. Gate Valves have a gate or wedge that moves perpendicular to flow of the service. In the up position, the valve is open. In the down position, the valve is closed. The distinct feature of a gate valve is the sealing of passages by the gate / wedge and seats. The gate faces are a wedge shape or parallel shape. The Gate Valves or Sluice Valves are opened by lifting a round or rectangular gate or wedge out of the path of the fluid in pipe.
Gate Valve
Solid Wedge Type
Parallel Slide Type
Gate valves are used to permit or prevent the flow of liquids, but not for regulating the flow. The flow path in gate valve is enlarged with respect to percent of opening. A partially open gate disk at the beginning tends to vibrate due to the fluid flow. Most of the flow make change near shutoff with a relatively high fluid velocity causing disk and seat wear and there is leakage if it is used to regulate flow. The gate valves are designed to be fully opened or closed. Gate valves have either a rising or a non-rising stem. Rising stems provide a visual indication of valve position because the stem is attached to the gate such that the gate and stem rise and lower together as the valve is operated. Nonrising stem valves have a pointer threaded onto the upper end of the stem to indicate valve position, since the gate travels up or down the stem on the threads without raising or lowering the stem. Nonrising stems are used underground or where vertical space is limited. Types of Gate Valves on the basis of Gate or Wedge: There are two types of gate valves depending on the disc design. They are: (i) Parallel gate valve: Parallel gate valve uses a flat disc gate between two parallel seats each at up upstream and downstream. Parallel gate valve is widely used the pipeline industry. The parallel gate valve needs some assistance to seal properly which is usually done in the form of a spring loaded or mechanically activated spreading action between the two disc halves. (ii) Wedge-shaped gate valve: Wedge-shaped gate valve is of three types: (a) Solid wedge: The solid wedge is the oldest form of gate valve and a drawback to this design is that it does not have any flexibility. There is the chance of solid disc getting jammed in the seats if there is any valve body/seat distortion due to extreme temperature fluctuations. (b) Flexible wedge: The flexible wedge gate valve has a groove or slot around its periphery, which can adapt to temperature changes and adverse piping stresses without binding. (iii) Split wedge: This is a two-piece design having mating surfaces on the back side of each disc half. This allows the downward stem thrust to be uniformly transferred to the disc faces and onto the seats. This provides protection against jamming due to thermal expansion. Types of Gate Valves on the basis of Body & Bonnet: There are five body/bonnet joint designs in gate valves. They are: (i) Screwed Bonnet: This is the simplest design available and it is used for inexpensive valves. (ii) Union Bonnet: This design allows for easier disassembly for repair and maintenance. (iii) Bolted-Bonnet: The most popular design and used in large number of gate valves. This requires a gasket to seal the joint between the body and bonnet. (iv) Welded-Bonnet: This is a popular design where disassembly is not required. They are lighter in weight than their bolted-bonnet counterparts. (v) Pressure-Seal Bonnet: The higher the body cavity pressure, the greater the force on the gasket in a pressure -seal valve. They are used extensively for high-pressure high-temperature applications. Gate valves are useful in applications involving slurries, heavy oils, varnish, light grease, steam, oil, gas, natural gas, honey, molasses, cream non-flammable viscous liquids, high pressure, high
temperature steam applications, and in chemical plant, refinery, pipeline industry, salt working pipelines, power industry and any other and industrial facility in the world. (iii) Globe Valve: Globe Valves are two-port valves openings in the body for fluid flowing in or out vertical to the flow stream in pipe. A Globe Valve is used for regulating flow, which consists of a movable disk-type element and a stationary ring seat in a body. This has an opening that forms a seat onto which a movable disc connected to a stem which is operated by screw action in manual valves. Automatic globe valves use sliding stems. Automatic globe valves have a smooth stem rather than threaded and are opened and closed by an actuator assembly. When a globe valve is manually operated, the stem is turned by a hand wheel. Globe valves are used for applications requiring throttling and frequent operation, like sampling valves, which are normally shut except when liquid samples are being taken. Globe Valves are not recommended where full, un-obstructed flow is required as the baffle restricts flow.
Butterfly valve
Gate Valve
Check Valve
Globe Valve
The bonnet is connected to the body and provides the containment of the fluid, gas, or slurry that is being controlled. The bonnet provides a leak proof closure for the valve body. The threaded section of the stem goes through a hole with matching threads in the bonnet. Globe valves may have a screwin, union, or bolted bonnet. Screw-in bonnet is the simplest bonnet, offering a durable, pressure-tight seal. Union bonnet is suitable for applications requiring frequent inspection or cleaning. It also gives the body added strength. A bonnet attached with bolts is used for larger or higher pressure applications. The bonnet also contains the packing, a wearable material that maintains the seal between the bonnet and the stem during valve cycling. The closure members of the valve are discs, which are connected to the stem and slid or screwed up or down to throttle the flow. Stems are either smooth for actuator controlled valves or threaded for manual valves. The seat ring provides a stable, uniform and replaceable shut off surface. Seat rings are usually held in place by pressure from the fastening of the bonnet to the top of the body. Globe valves consist of the following movable parts: the disk; the stem, and the hand wheel. The stem is the connection between the hand wheel and the disk. Type of Globe valves: Globe valves are available in three main body designs, they are as follows: (i) Angle design: The inlet and outlet are perpendicular to each other and the purpose is to transferring flow from vertical to horizontal; (ii) Y-design: Here, the globe valve derives its linear action from the incline between the inlet's axis and outlet ports; (iii) Multi-piece design: In the multipiece design, the bodies of valves are bolted together and here the inlet and the outlet are not of single piece construction. Features of globe valves: Liquid flow does not pass straight through globe valves. Therefore, it causes an increased resistance to flow and a considerable pressure drop. A globe valve opens in direct proportion to the number of turns of its actuator, which allows globe valves to closely regulate flow, even with manual operators. Most globe valves have outside screw rising stem construction. Here the threads are away from the line fluid and hence they are easy to lubricate.
Globe valves are suitable for most on off, non-vibrating hydrocarbon or utilities service for all temperature ranges. Globe valves have better torque characteristics than ball valves or plug valves, but do not have the easy operability of quarter turn action. Globe valves with unprotected rising stems are not recommended since the marine environment can corrode exposed stems and threads, making the valves hard to operate and damaging stem packing. Globe valves are used for throttling service. Globe valves are suitable for throttling especially with fluids containing sand can damage the sealing surfaces and when good throttling control is required. (iv) Butterfly valve: A Butterfly Valves stop, regulate, and allow the fluid flow easily and quickly because there is a 90 degree rotation of the handle which moves the disk from a fully closed to fully opened position. Butterfly valves provide a high capacity with low-pressure loss and are durable, efficient, and reliable and have their seating surface. The disc impinges against a resilient liner and provides bubble tightness with very low operating torque. Butterfly valves exhibit an approximately equal percentage of flow characteristics and can be used for throttling service or for on/off control. It is difficult to accomplish a leak-tight seal with a butterfly valve. Where a tight seal is required, these valves should be limited to low-pressure, low-temperature (200 psig, 150 0F) water service. Butterfly valves are suitable for throttling applications in water service and other applications where a tight shutoff is not required. The Butterfly valve uses a flat plate to open and close the pipe system and to control the flow of water. Manually operated butterfly valves are closed quickly by 900 turn of the handle, which allows for quick shut off and thus there is a danger of water hammer. Some butterfly valves are equipped with an actuator that may be pneumatically or motor operated. Butterfly valves are generally favoured because they are lower in cost to other valve as well as being lighter in weight, meaning less support is required. The disc is positioned in the centre of the pipe, passing through the disc is a rod connected to an actuator on the outside of the valve. Rotating the actuator turns the disc either parallel or perpendicular to the flow. Unlike a ball valve, the disc is always present within the flow; therefore a pressure drop is always induced in the flow, regardless of valve position. Diaphragm Check Butterfly Butterfly Valve Valve Valve
There are different kinds of butterfly valves, each adapted for different pressures and different usage. The resilient butterfly valve uses the flexibility of rubber and has the lowest pressure rating. The high performance butterfly valve, used in slightly higher-pressure systems increases the valve's sealing ability and decreases its tendency to wear. The valve best suited for high-pressure systems is the triple offset butterfly valve, which makes use of a metal seat and is therefore able to withstand a greater amount of pressure. Types of Butterfly Valves: 1) Concentric Butterfly Valves: This has a resilient rubber seat with a metal disc. 2) Double Eccentric Butterfly Valves: These are also referred as 'High Performance Butterfly Valves' or 'Double Offset Butterfly Valves'. Different type of materials is used for seat and disc. 3) Triple Eccentric Butterfly Valves: These are called 'Triple Offset Butterfly Valves'. Triple
offset valves are generally used in applications which require bi-directional tight shut-off in Oil & Gas for dirty/ heavy oil to prevent extrusion. Parts of a Butterfly valve: The butterfly valve consists of only five main components. They are as follows: Body: These valves have bodies that fit between two pipe flanges. Disc: The disk is the flow closure member of a butterfly valve. Stem: The stem of the butterfly valve is either a one-piece shaft or a two-piece, also known as split-stem design. Seat: The seat of a butterfly valve utilizes an interference fit between the disk edge and the seat to close or to shutoff. (v) Check valve: Check valves, in the open position allows forward flow and in closed position blocks the reverse flow. They are self-actuated and are meant for stopping the fluid flow. These valves are opened, and sustained in the open position, by the force of the liquid velocity pressure. The force of gravity or backflow closes them as and when required, automatically. The seating load and tightness is dependent upon the amount of backpressure. Check Valve or “Non-Return Valve” or “One-Way Valve” allows fluid to flow through it in only in one direction. Check Valve are used to prevent flow reversal in piping systems. Check Valve is a mechanical device that allows fluid to flow through it in only one direction. Check valves work automatically and do not have any valve handle or stem. An important concept in check valves is the cracking pressure, which is the minimum upstream pressure at which the valve will operate. Check Valve is specified for a specific cracking pressure. Types of Check Valves: Check valves work automatically and do not have any valve handle or stem. They are self-activating safety valves. They permit gases and liquids to flow in only one direction. There are various types of check valves used in a variety of applications. Typical check valves include Ball Check Valve, Swing Check Valve, Tilting Disc Check Valve, Lift Check Valve, and Stop Check Valve. Other check valve types are also available, however, like below: (i) Ball Check Valve: Ball Check Valve has a spherical ball, which block the flow. In some ball check valves, the ball is spring-loaded to help keep it shut. The interior surface of the main seats of ball check valves are more or less conically-tapered to guide the ball into the seat and form a positive seal when stopping reverse flow. A ball check valve, in the open position allows forward flow and in closed position blocks the reverse flow. Ball check valves are often very small, simple, and cheap. They are commonly used in liquid. Ball check valves are very similar to lift plug check valves. Since the ball is lifted by fluid pressure, this type check valve does not have a tendency to slam, as does a swing check valve. It is therefore preferable in sizes 2 inches or smaller for clean services that have frequent flow reversals. (ii) Lift Check Valve: Lift Check Valve has the disc, which is lifted up off its seat by higher pressure of inlet or upstream fluid to allow flow to the outlet or downstream side. A guide keeps motion of the disc on a vertical line, so the valve can later reseat properly. When the pressure is no longer higher, gravity or higher downstream pressure will cause the disc to lower onto its seat, shutting the valve to stop reverse flow. Lift Check Valves also operate automatically by line pressure. (iii) Diaphragm Check Valve: Diaphragm Check Valve uses a flexing rubber diaphragm positioned to create a normally-closed valve. Pressure on the upstream side must be greater than the pressure on the downstream side by a certain amount, known as the pressure differential, for the check valve to open allowing flow. Once positive pressure stops, the diaphragm automatically flexes back to its original closed position. (iv) Swing Check Valve: Swing Check Valve or tilting disc check valve has the movable disc, which swings on a hinge or Trunion to block the flow, either onto the seat to block reverse flow or off the seat to allow forward flow. The seat opening cross-section is perpendicular to the centreline between the two ports or at an angle. Large check valves are often
swing check valves. Swing check valves are used to prevent flow reversal in horizontal direction or in vertical upward direction. Swing check valves have discs that swing open and closed. The split disc swing checks valve is a variation of the swing check design. The springs used to effect closure may be subject to rapid failure due to erosion or corrosion. (v) Tilting Disc Check Valve: Tilting disc check valves are pivoted circular discs mounted in a cylindrical housing. These check valves have the ability to close rapidly, thereby minimizing slamming, and vibrations. Tilting disc checks are used to prevent reversals in horizontal-flow or vertical-up line flow, similar to swing check valves. Ivi) Stop Check Valve: Stop check valves have a floating disc. Stop check valves are used in high pressure and hazardous applications. Sizing of these valves is extremely important. Stop Check Valve override control to stop flow regardless of flow direction or pressure. In addition to closing in response to backflow or insufficient forward pressure (normal check-valve behaviour), it can also be deliberately shut by an external mechanism, thereby preventing any flow regardless of forward pressure. (vii) Lift Plug Check Valve: Lift plug check valves are only used in small, high-pressure lines, handling clean fluids. Lift plug valves can be designed for use in either horizontal or vertical lines, but the two are not interchangeable. Since lift plug valves usually depend on gravity for operation, they may be subject to fouling by paraffin or debris. (viii) Piston Check Valve: Piston check valves are recommended for pulsating flow, such as reciprocating compressor or pump discharge lines. They are not recommended for sandy or dirty fluid service. Piston check valves are equipped with an orifice to control the rate of movement of the piston; Orifices used for liquid services are considerably larger than orifices for gas services. A piston check valve designed for gas service should not be used in liquid service unless the orifice in the piston is changed. (vi) Needle valve: Needle valves pinch an elastomeric sleeve shut in order to throttle the flow through the pipeline. Because of the streamlined flow path, the Needle valve has very good fluid capacity. Needle valves typically have a fairly linear characteristic. This position will vary the rate of stem change as a function of position in order to match the flow characteristics desired. In some instances, the cams are set up to provide an equal percentage flow characteristic through a Needle valve. In the Needle valve, the throttling takes place in the elastomeric sleeve, and elastomeric typically has very good abrasion resistance; Needle valves are often used for sampling point. Needle Valves are basically miniature globe valves. They are frequently used for instrument and pressure gage block valves, for throttling small volumes of instrument air, gas or hydraulic fluids, and for reducing pressure pulsation in instrument lines. The small passageways through needle valves are easily plugged, and this should be considered in their use. Needle Valves have a small port and a threaded, needle-shaped, plunger. It allows precise regulation of flow at relatively low flow rates. A needle valve has a relatively small orifice with a long and tapered seat and a needle-shaped plunger on the end of a screw, which exactly fits this seat. Needle Valve is used to make relatively fine adjustments in the amount of fluid flow. This valve is used widely because of its excellent control of flow. However, instead of a disk in globe valve, a needle valve has a long tapered point at the end of the valve stem. Since it takes many turns of the fine-threaded screw to retract the plunger, precise regulation of the flow rate is possible. The virtue of the needle valve is from the vernier effect of the ratio between the needle's length and its diameter, or the difference in diameter between needle and seat. A long axial travel while controlling the input makes for a very small and precise change affecting the resultant flow. Needle valves may be used in vacuum systems, when a very precise control of gas flow is required, at low pressure, such as when filling gas-filled vacuum tubes, gas lasers and similar devices. Needle valves are used in flow metering applications, especially when a
constant, calibrated, low flow rate must be maintained for some time, such as the idle fuel flow in a carburettor. Since flow rates are low and many turns of the valve stem are required to completely open or close, needle valves are not used for simple shutoff applications. Since the orifice is small and the force advantage of the fine-threaded stem is high, needle valves are usually easy to shut off completely, with merely "finger tight" pressure. Small, simple needle valves are often used as bleed valves in hot water heating applications. Unlike a ball valve, or valves with a rising stem, it is not easy to tell from examining the handle position whether the valve is open or closed.
Applications of Needle Valve: Needle Valve is suited for aggressive and high purity chemicals. Needle valves are applied in situations where the flow must be gradually brought to a halt. They are also used where precise adjustments of flow are necessary or where a small flow rate is desired. (vii) Choke valve: Choke valve raises or lowers a solid cylinder which is placed around or inside another cylinder, which has holes or slots and is used for high pressure drops found in oil and gas wellheads. (viii) Diaphragm valve (Membrane/ Bladder Valves): Diaphragm valves consist of a valve body with two or more ports, a diaphragm, and a "saddle" or seat upon which the diaphragm closes the valve. Their application is generally as shut-off valves in process systems in industries In Diaphragm Valve, a diaphragm made of an Elastomeric is connected to the valve stem. Closure is accomplished by pressing the diaphragm against a metal weir, which is a part of the valve body. Diaphragm valves are used primarily for low-pressure water (200 psig or less) service. They are especially suitable for systems containing appreciable sand or other solids. Diaphragm Valve controls flow by a movement of a diaphragm. Upstream pressure, downstream pressure, or an external source, e.g., pneumatic or hydraulic media, is used to change the position of the diaphragm. There are two main categories of diaphragm valves, such as, (i) seals over a "weir" (saddle) and (ii) seals over a seat. The main difference is that a saddle-type valve has its two ports in line with each other on the opposite sides of the valve, whereas the seat-type has the in/out ports located at a 90 degree angle from one another. The saddle type is the most common in process applications and the seat-type is more commonly used as a tank bottom valve but exists also as a process valve. Diaphragm valves can be manual operated or automatic. Diaphragm valves can be controlled by various types of actuators e.g. manual, pneumatic, hydraulic or electric. The most common diaphragm valves use pneumatic actuators; where air pressure is applied through a Schrader valve which raises the diaphragm and opens the valve. This type of valve is extremely quick and as such is one of the more common valves used in operations where valve speed is a necessity. Diaphragm is made of Natural Rubber, Nitrile, Buna-N, EPDM, Viton, Silicone rubber or Fluorine Plastic (FEP/F46, PTFE/F4, PFA, all with EPDM back). (ix) Control Valve: A Control Valve is a full bore or full port valve which uses a pinching effect to
obstruct fluid flow. Major components of a Control Valve consist of body and a sleeve. A Control Valve is the best type of valve for flow control application if the operation temperature is within the limit of the polymer. Air operated Control Valve are very common. They generally consist of an extremely elasticized reinforced rubber hose, a type of housing, and two socket end covers or flanges. The rubber hoses of the air operated Pinch Valves are usually press-fitted and centred into the housing ends by the socket end covers or flanges. The air operated Control Valve works without any additional actuator; all it needs to close or operate is 30 psi air supply into the Control Valve body. As soon as the air supply becomes interrupted and the volume of air exhausts, the elastic rubber hose starts to open due to its great impact resilience. The most important benefits of using air operated Control Valve are their complete and true full bore, and the 100% tight shut off – even on solids such as granules, powders, pellets, chippings, fibres, slivers, any kind of slurries and many more aggressive products. Usually conventional valves such as ball valves, butterfly valves, piston valves or gate valves tend to fail when in process with the above mentioned aggressive products. The reason is that the valve body seat or the gate/piston of the valves wears out too quickly and the valve can no longer shut off tightly, whereas air operated Control Valves work without almost any wear of the elastic rubber hose because the kinetic energy of the solids are absorbed through the extremely high elasticity of the rubber. The rubber mixture is also anti abrasive. Productivity, efficiency and accurate control are the objective of any steam system.
Fig: Control Valve
Fig: Piston Valves
(x) Piston valve: Piston valves are used for regulating fluids that carry solids in suspension. A 'piston valve' is a used to control the motion of a fluid along a pipe by means of the linear motion of a piston within a chamber or cylinder. Cylindrical piston valves are used to change the length of tube in the playing of most brass instruments, particularly the trumpet-like members of the family. (xi) Plug valve: Plug valves have tapered cylindrical plugs or conically-tapered "plugs", which can be rotated inside the valve body to control flow through the valve. Plug valves are available in various types like given below:
The plugs have one or more hollow passageways through the plug, so that fluid can flow through the plug when the valve is open. Plug valves are simple and often economical. Plug valves are also known as cock or stop-cock valves. Plug valves are widely used for both on/off and throttling services. The stem/handle is attached to the larger diameter end of the plug exposed outside the valve body. The stem and handle often come in one piece. The ports are typically at opposite ends of the body; therefore, the plug is rotated a quarter-turn to change from open to shut positions. Plug valves are suitable for the same applications as ball valves and are also subject to similar temperature limitations. Plug valves are available in either lubricated or non-lubricated designs. Lubricated plug valves must be lubricated on a regular schedule to maintain a satisfactory seal and ease of operation. In the non-lubricated design, Teflon, nylon or other “soft” material accomplishes the seal. They do not require frequent maintenance lubrication but may be more difficult to free after prolonged setting in one position. Plug valves are high capacity valves that are found widely in low pressure industrial applications. They are extremely versatile valves that can be used for directional flow control. They are used even in moderate vacuum systems. Plug valves can efficiently handle gas and liquid fuel. They are safely handling extreme temperature flow, such as boiler feed water, condensate, and other such elements. They are used to regulate the flow of liquids containing suspended solids, for example, slurries. (xii) Pressure Safety valve/ Pressure Relief Valves: Pressure relief valves are automatic pressure relieving devices that protect piping systems and process equipment. The valves protect systems by releasing excess pressure. During normal operation, the valve disc is held against the valve seat by a spring. The spring is adjustable to the pressure at which the disc lifts. The valve disc lift is proportional to the system pressure so that, as the system pressure increases, the force exerted by the liquid on the disc forces the disc up and relieves the pressure. The valve will reseat when the pressure is reduced below the set spring pressure. Pressure Safety Valve is a device for relieving excess pressure or vacuum automatically from a boiler, pressure vessel, or other system, when the pressure or temperature exceeds preset limits. It is also called “Pressure Safety Valve (PSV)” or “Pressure Relief Valves (PRV)”. Safety valves are used on steam boilers and Vacuum safety valves or Combined Pressure / Vacuum Safety Valves are used to prevent a tank from collapsing while emptying it or when cold rinse water is used after hot CIP or SIP. Safety Valves protect equipment such as Pressure Vessels and Heat Exchangers handling compressible fluid application (gas, vapour, or steam) from (i) excess pressure due to thermal protection and (ii) flow protection. Pressure Relief Valves against thermal protection are relatively small in size that provides protection from excess pressure caused by thermal expansion. In this case a small valve is adequate because most liquids are nearly incompressible, and so a relatively small amount of fluid discharged through the relief valve
will produce a substantial reduction in pressure. Pressure Relief Valves against flow protection are considerably larger than those mounted in thermal protection.
Pilot-operated Safety Relief Valve (POSRV): Automatic system that relieves on remote command from a pilot to which the static pressure (from equipment to protect) is connected. Low Pressure Safety Valve (LPSV): Automatic system that relieves static pressure on a gas. Used when the difference between the vessel pressure and the ambient atmospheric pressure is small. Vacuum Pressure Safety Valve (VPSV): Automatic system that relieves static pressure on a gas. Used when the pressure difference between the vessel pressure and the ambient pressure is small, negative and near the atmospheric pressure. Low and Vacuum Pressure Safety Valve (LVPSV): Automatic system that relieves static pressure on a gas. The pressure is small, negative or positive and near the atmospheric pressure. Rupture Discs Valve: Rupture discs rupture automatically at a predetermined pressure and will not recluse. These discs can relieve very large volumes of liquid in a rapid manner. Materials of construction include metals, graphite or plastic materials held between special flanges and of such a thickness, diameter and shape, and material, that it will rupture at a pre-determined pressure. Reduced Pressure Backflow Prevention: Backflow prevention is handled by three main methods, one by check valves, and another by pressure and vacuum breakers, and the third by a reduced pressure backflow prevention assembly.
The pressure relief valves are a kind of safety valve, used widely in various industrial applications. They are self-actuated valves manufactured to relieve excess pressure upstream from the line. They are designed in such a way so as to provide protection from over-pressure in steam, gas, air and liquid lines. The pressure relief valve "lets off steam" when safe pressure exceeds, and close automatically when pressure drops to a preset level. The main purpose of pressure relief valve is to provide protection from over-pressure in steam, air, gas and other liquid lines. (xiv) Sampling valve: A Sampling Valve allows taking a representative portion of a fluid for laboratory test. The Sampling Valve allows the operator to extract a sample of the product from the production line or reactor and safely store it for transportation to the laboratory where it will be analyzed or to the archive room where it can be retrieved for further use. Sampling raises two problems. (i) If the liquid is a chemical substance that solidifies at room temperature such as polymer or other plastics, it can block the valve and prevent a second sample to be taken. The residue of the chemical substance that was flushed needs to be recycled or destroyed at a cost both for the chemical plant and the environment. It is extremely important that the operator is not exposed to toxic fumes or vapours when sampling hazardous chemicals or deadly substances. These can fatally harm people and pollute the environment if released in the atmosphere. The different factors, like, material, pressure,
temperature rating, gaskets, size and position of the valve shall be considered for a Sampling Valve according to the pipe specification of the plant. (xv) Control valves: Control valves are used to control the flow, pressure, temperature or liquid level by fully or partially opening or closing in response to signals received from controllers that compare a "set point" to a "process variable" whose value is provided by sensors that monitor changes in such conditions. The opening or closing of control valves is done automatically by electrical, hydraulic or pneumatic actuators. Positioners are used to monitor the opening or closing of the actuator based on electric or pneumatic signals. Perforated trim is used to reduce the noise level by splitting the flow into multiple independent streams. Due to the complexity of the fluid flow, noise and cavitations calculations often required to size and select an appropriate control valve. These control signals are based on 3-15 psi (0.21.0 bar) pressure or 4-20 mA current signals for industry and 0-10V for HVAC systems. The choice of valve for a particular application depends on various factors such as the fluid flow rate, the process temperatures and pressures, and whether the fluid is corrosive or abrasive. The most common and versatile types of control valves are sliding-stem globe and angle valves. The capacity of a valve is measured in Cv, Kv or Av and can be determined experimentally for a valve by testing it by measuring the amount of water that flows through it at a certain pressure differential across the valve. (xvi) Pinch Valves: Pinch valves are full bore type of control valve. There is no obstruction to flow passage. These kinds of valves are ideally suited for the handling of slurries, liquids with large amounts of suspended solids. They are used in systems that convey solids pneumatically. Pinch valve are linear action valves that can be used in both an off / on manner or in throttling service or in a variable position.
Major components of a pinch valve are Stem, Body (Sleeve) and Pinching device. Pinch valves are closed either by fluid actuation or manual means. Electro-mechanical closure takes place by actuating a solenoid, which in turn lowers a bar or gate onto the sleeve, cutting off the flow. With fluid actuated pinch valves, the pinching action is completed by air or hydraulic pressure placed directly on the elastomeric sleeve. The pinch valve body acts as a built-in actuator, which eliminates costly hydraulic, pneumatic, or electric operators. The pinch valve is closed mechanically with the
movement of the pinch bars located on opposite sides of the sleeve. Pinch Valves offer position indication and noise reduction. They are used in the waste treatment plant. They are useful in the handling of lime slurry and carbon-impregnated activated sludge. Pinch Valves are considered to be reliable, maintenance-free, cost-effective valves. They are capable of handling the most abrasive, tough slurries, dry solids in process industries and corrosive chemical applications. Pinch Valves are just ideal to solve all process problems which are associated with abrasive or corrosive fluid handling in various areas like: Pulp and paper, Mineral processing, Power generation, Chemical handling, Effluent treatment and Water and wastewater handling. (xvii) Pressure Reducing Valves: A pressure reducing valve, a popular category of pipe valve, is used widely to reduce pressure in fluid flow, be it steam, air or gas or any kind of liquid. This type of valve is also known as “Pressure Regulator”. It is a kind of throttling device. The pressure reducing valve gives a constant reduced pressure in spite of fluctuations, within reasonable limits and within the inlet pressure that is the incoming high pressure. A pressure reducing valve automatically reduces the pressure from the water supply main to a lower and a more sensible pressure. This continues so long the supply pressure does not drop below the valve’s pre-set pressure.
(xviii) Air and Vacuum Relief Valves: In process piping in which air tends to collect within the lines, air-release valves are necessary. A very common operating problem occurs when air collects in the high places of the piping systems, producing air pockets. These air pockets can reduce the effective area of the pipe through which the liquid can flow, causing a problem known as air binding. Air binding results in pressure loss, thus increasing pumping costs. During start-up, shutdown or during operation, it is common for process piping system to produce situations where air needs to be exhausted or allowed to re-enter. The devices used include air-release valves, air-vacuum valves, vacuum breakers, and combination air-release and air-vacuum valves. Air-release valves, if installed on the line, eliminate these problems. Air-release valves should be installed at pumping stations where air can enter the system, as well as at all high points in the pipeline system where air can collect. Air-release valves automatically vent any air that accumulates in the piping system while the system is in operation and under pressure.
Vacuum Breaker
Pressure and Vacuum Breaker
The air-vacuum valves are used to prevent damage to the piping system due to over-pressurization, velocity surges during filling, or collapse during draining. Air-vacuum valves are installed at piping high points. These valves are float operated, have large discharge and inlet ports that are equal in size, and automatically allow large volumes of air to be rapidly exhausted from or admitted into a pipeline. Air-vacuum valves will not vent gases when the piping system is in normal operation and under pressure. Air-release valves are designed for that purpose. (xix) Blow down Valves: The blow down valves is used for operation in open position. The main function of blow down valve is to control a continuous flow of steam /fluid under high differential pressure.
At start-up, the blow down valve closes. This leads the air-oil separator pressure to build up. At shut-down the valve opens to bleed the air-oil separator to atmosphere. This is when a pressure is applied. The valve can also be used as a by-pass valve to bleed air with the help of the compressor at start-up. These valves are appropriate for use with air compressors. They are used to help in the removal of slug and unwanted materials after cleaning the pipes. Blow down valves are found on the water feeders. They are also used to lower water cut-offs. They can control the concentration of solids in the boiler. (xx) Foot Valves: A foot valve is a kind of check valve fitted on the foot of a suction line to prevent backflow. A foot valve is placed in the water source below a surface pump. The basic function is to prevent water from flowing back down the pipe. In other words, it is a valve to allow the pump to pull water up but does not allow the water to flow back down. This helps in keeping the pipe full of water while the pump is not running. This kind of valve is available in a variety of shapes, sizes, and materials. Foot Valves prevent the pump column from draining upon pump shutdown. They are widely applied to all kinds of pneumatic system. They are used in a suction line of the pumping system in a well. They provide a positive sealing action at both low and high pressures without slamming.
Female threaded Foot Valve
Dual purpose threaded foot valve
Dual threaded foot valve
5.5
Piping other Components
(i) Strainers: Strainers are placed in-line with process piping to remove large solid contaminants from the flow. Strainers filter particles and contaminants from fluids. They provide a high degree of resistance to corrosive substances such as acids and solvents and other toxic fluids. The strainer helps screen out particulate matter in a piping system. Strainers play an important role in the efficient operation of a well-designed system. There are two types of strainers widely used in industries: (i) Y-type strainers and (ii) T-type strainers. Strainers can be cleaned and reused. Strainer assemblies come equipped with housing, cover, or case and a strainer element. Straining sieves are stainless steel or brass round frames with extremely accurate openings. Wire cloth is usually of stainless steel or brass with nonstandard wire diameters. Strainers is provided in all pump and compressor suction lines and is located as close as possible to the inlet flanges, with consideration for later removal & set of breakout flanges are required to remove the screens. The screens is checked during start-up and removed when sediment is no longer being collected. Caution should be exercised in screen selection and use to avoid creating NPSH problems. Basket Type Strainers are used where a line can be shut down for short periods to clean or change strainers. They are an integral part of the pipeline because all flow passes through them. Duplex Basket Type Strainers remove damage-causing particulate matter from the process media. Because they never have to be shut down for cleaning, a line can run continuously. When one strainer basket becomes full, flow is switched to the other. The first basket is removed, cleaned, and readied for use again. In-line Strainers are positioned with the basket parallel to the line of fluid flow. They are used in sanitary applications. Tee Type Strainers are well-suited for applications in which replacements must be made quickly. YType Strainers use a perforated or wire mesh straining element to remove solids from flowing liquids or gases.
Flat Plate Type Strainers are inserted directly in the line of fluid flow. They may also be used while held in the hand. Flat plate strainers are designated as temporary, and used for start-up only. (ii) Air Vent: Air Vent operation increases system efficiency by automatic and continuous removal of air/gas from a pressurized liquid. The air vents are available in a wide variety of sizes, end connections and construction materials. The thermostatic air vents are good for positive venting of air.
Operation is completely automatic, and the simple design and quality mechanism make operation trouble-free and maintenance infrequent. Air can accumulate in remote sections of chamber-type heattransfer equipment such as jacketed kettles, retorts, vulcanizers and jacketed sterilizers. (iii) Steam Traps: The steam trap is used in the steam line to discharge the condensate from the steam in steam piping without allowing steam to escape from the line. The condensed steam or condensate from lowest point of steam line, where a condensate water pocket exists, is continuously drained automatically to prevent the water hammer and a possible rapture of the steam pipe. The condensate is drained at every interval of 100 meter to 125 meter. For the purpose of draining the condensate, a proper drip line from the steam headers, main line or separators is installed up to the stem trap point. The steam traps are classified according to the type of operating device by which they function. There are following three types of steam traps. a) Float Type: The float trap has a hollow float, which rises with rise of the accumulated condensate water in the valve and actuates the lever to open the valve and to discharge the condensate water from the steam line. b) Bucket Type: The condensate water spills over the top of the bucket of the steam trap, which causes the bucket to sink in the vale and actuate the lever to open the steam trap valve and thus discharge the condensate water intermittently out of the valve. c) Impulse Type: In the Impulse type trap, the flashing of the hot condensate water tends to force a small piston into the discharge opening when the temperature of the condensate downs to 300 F of the saturation temperature. When the temperature of the condensate collected in the drain cools down sufficiently below the flash temperature, the trap opens and discharges the condensate, accumulated in the drain, until the temperature of the condensate again reaches to the saturation temperature and flashes by closing the trap. This cycle is repeated very frequently to discharge the condensate from the trap regularly. g) Thermodynamic Type: The thermodynamic traps have only one moving part, i.e. a valve disc. The valve disc is operated by the kinetic energy of the steam. The construction of the trap consists of three chambers, (1) inlet, (2) outlet and (3) the chamber disc in which a single and common disc closes the inlet and outlet port by one side of disc and makes a chamber on the backside of the disc. (iv) Flexible Couplings: Flexible couplings are used to join pipe sections, to insulate sections from one other, to absorb concentrated pipe movement, and to join plain end pipe to flanged valves and other equipment. The basic purpose of flexible couplings is to provide flexible but leak-tight connections that will last for the life of the piping. Flexible couplings are generally available in sizes from 15 mm (½ in) and larger. a. Metallic Flexible Couplings: The basic configuration of a Metallic flexible coupling is a metallic middle ring that slips over the joint between two pipe sections with a gasket and a follower at each end. This configuration compresses the gasket and seals the middle ring. The middle ring can be provided in standard in a number of different materials. b. Transition Couplings: The transition couplings connect pipe with a small difference on outside diameter. The middle ring in transition couplings is pre-deflected to adjust for the differences in diameter. As with the Metallic flexible couplings, the transitional coupling's middle ring and gaskets are available in different materials, depending upon the application.
Figure: Flexible Coupling (Source: Dresser Industries, Inc., “Style 38 Dresser Couplings for Steel Pipe) c. Flanged Couplings: Flanged couplings are typically provided with a compression end connection on one end and a flange on the other. (v) Expansion Loop (Pipe Compensators): Thermal expansion in piping can impact the design of the piping system in the following critical areas: 1. Excessive stress related to thermal loads on the liquid being contained by the piping system. 2. Reduction of allowable stress due to elevated material temperature and stresses caused by elongation of the metal pipe. 3. Excessive thrust loads or bending moments at connected equipment due to thermal expansion of the metal pipe. 4. Leaking at pipe joints due to thermal expansion of the metal pipe. Piping must be designed for thermal expansion under start-up, operating and shut down conditions without over stressing the piping, valves, or equipment. A pipe will expand due to heating and contract due to cooling. This can be expressed through the following expansion formula. The expansion of pipes depends on the final temperature of the pipe and the expansion coefficient of the piping material. The general expansion formula can be expressed as: L = α Lo dt Where, L = expansion (ft); Lo = length of pipe (ft); dt = temperature difference (oF); α = Mean Coefficient of Linear Expansion (inch/inch oF); Mean Coefficient of Linear Expansion may vary with temperature as shown below: Table: Mean Coefficient of linear Expansion Mean Temperature Range (o F) Expansion Coefficient 32 - 32 - 32 - 32 - 32 - 32 - 32 α - - 32 212 400 600 750 900 1100 1300 (inch/inch
o
F) x10-6 Alloy Steel (1% Cr. 7.7 1/2% Mo) Mild Steel (0.1 - 0.2% 7.1 C) Stainless Steel (18% 10.8 Cr. 8% Ni)
8.0
8.4
8.8
9.2
9.6
9.8
7.8
8.3
8.7
9.0
9.5
9.7
11.1
11.5
11.8
12.1
12.4
12.6
12.8
The above formula can also be used with SI units. The expansion coefficient must of course be adjusted to o C. Example: Expansion due to heating of Alloy Steel: The length of 100 feet of alloy steel pipe is heated from 32 o F to 212 o F. The expansion coefficient is 8x10-6 (inch/inch o F). The expansion can be expressed as: L = (8x10-6 inch/inch o F) x (100 feet) x (12 inch/feet) x (212 32) = 1.728 inch Hence, all lines, which normally contain flammable or toxic materials, shall be provided with adequate flexibility for steam out conditions at temperature of 120 C by adopting the suitable Expansion Compensators. Expansion Compensators, such as Swivel Joints or Expansion Loops can handle pipe movement. U shaped Expansion Loops are preferred when practical. Swivel joints may be subject to leakage and must be properly maintained. Swivel Joints may be subject to failure if improperly installed and should be avoided in pressure piping. Swivel Joints are often used in engine exhaust systems and other low- pressure systems. When designing a piping system subject to thermal expansion due to anticipated operating temperatures, the piping is restrained at supports, anchors, and equipment nozzles. The thermal stresses and loads may be large and must be analyzed and accounted for within the design. The system PFDs and P&IDs are analyzed to determine the thermal conditions or modes to which the piping system will be subjected to during operation. Based on this analysis, the design and material specification requirements are followed as an applicable standard. The need for detailed thermal stress analysis is assessed for piping systems. The first approach is to identify the operating conditions that will expose the piping to the most severe thermal loading conditions. Once these conditions have been established, a free or unrestrained thermal analysis of the piping is performed. If the stress resulting from thermal expansion is less than 68.9 MPa (10 ksi), the pipe section analyzed has sufficient flexibility to accommodate the thermal expansion and rigid supports can be utilized. The terminal loadings on equipment determined from this analysis can then be used to assess the equipment capabilities for withstanding the loading from the piping system. It should also be noted that this analysis at equipment and anchor terminations should consider the movement and stress impacts of the “cold” condition. If the initial free thermal analysis indicates that the resulting stresses will require the piping system to be designed to accommodate thermal expansion, the design should conform to applicable codes and standards. A basic approach to assess the need for additional thermal stress analysis for piping systems includes identifying operating conditions that will expose the piping to the most severe
thermal loading conditions. Once these conditions have been established, a thermal analysis of the piping can be performed to establish location, sizing, and arrangement of expansion loops, or expansion joints (generally, bellows or slip types). Type of Expansion Loops and its Application: (I) Simple Expansion Joints: Expansion joints may be used on large diameter piping, relief systems or other process lines, where economically justified provided they are designed for minimum 7000 cycles. Expansion joints are used to absorb pipeline expansion typically resulting from thermal extensions. The use of expansion joints is often required where expansion loops are undesirable or impractical. However, expansion joints are not used for direct buried service. Expansion joints are available sleeve type, slip-type, ball, and bellows configurations. a. Sleeve Type Expansion Joints: Sleeve Type is a Slip-type expansion joints where a sleeve that telescopes into the body. Packing located between the sleeve and the body controls leakage. Because packing is used, a leak-free seal is not assured. Properly specified, these expansion joints do not leak; however, because packing is used, these expansion joints should not be used where zero leakage is required. Occasional maintenance is required to repair, replace, and replenish the packing. Slip-type joints are particularly suited for axial movements of large magnitude. They cannot, however, tolerate lateral offset or angular rotation due to potential binding. Therefore, pipe alignment guides are necessary with slip-type expansion joints. b. Ball Expansion Joints: Ball expansion joints consist of a socket and a ball, with seals placed in between the two parts. Ball expansion joints can handle angular and axial rotation; however, they cannot tolerate axial movements. c. Bellows Type Expansion Joint: It is capable of absorbing any movement in any direction, axially, laterally, angularity or any combination of these. It consists of corrugated bellows linked together by a section of pipe with control rods. Where there is a short leg or offset at right angle to a long run of pipe universal expansion joints are frequently used. It is also frequently used with tie rods for lateral deflection where loading on anchors or equipment is to be kept to a minimum. Guides should always be provided near the joint not only to control the movement but also to take the weight of pipe. d. Tied Expansion Joint:Where there is a problem of anchoring and high compressive load, a tied type expansion joint is used because it carries the internal thrust. It absorbs lateral deflection and rotation, absorbs the expansion of all the piping contained within its length. It can only be used with a change indirection of the piping, preferably 90 . e. Hinged Expansion Joint: Where there is a problem of anchoring, supporting and allowable forces and moments on equipment nozzles, hinged expansion joint is used. Hinged expansion joint is used, when (I) Carries weight of piping and other dead loads without danger to bellows. (II) Proves most rigid system (III) Permits rotation only of bellows in one plane (IV) Prevents torsion on bellows (V) absorbs all pressure thrust (VI) can absorb axial compression combined with rotation when designed with slotted hinges but will not absorb pressure thrust under this condition. f. Pressure Balanced Expansion Joint: It is designed to overcome load due to internal pressure. It is used for pipeline service where the installation of main anchors occurs at a change in direction of the piping. This load is composed of thrust due to internal pressure. Balanced expansion joint can only be used at a change in direction and absorb the pressure thrust. Only the force required to compress and elongate the bellows is imposed on the anchors or adjacent equipment during operation. g. Pressure Balanced Universal Expansion Joint: This is similar to pressure balanced units, except that they can absorb considerably more lateral deflection. This expansion joint consists of two corrugated bellows in the line linked together by a section of pipe with control rod tied to the
balancing expansion joint. The balancing end is only required to compensate for the axial movement while the universal expansion joint absorbs both axial movement and lateral deflection. The Expanded Joints should be installed as per the instruction of the manufacturer and care should be taken to ensure the adequate engagement of the joint members. All Expansion Joints /Expansion Bellow’s design is the manufacturer responsibilities. The expansion joints manufacturer should provide the detail design and fabrication for all elements of the expansion joints in accordance with the requirement of the code ANSI B 31.3, Appendix ‘F’, Appendix ‘X’ and as per guidelines given in EJMA. However, piping designer may also design the expansion joint considering the requirements of the above-referred codes. (II) U-Loop Pipe Compensator: An alternative is an expansion loop. U-Loop Expansion joint is made of the same piping material of the main pipe header but in the U-Form, which can be used in vertical or horizontal planes. If an expansion loop is to be required, the following formula can be used. This formula is based on guided-cantilever-beam theory in which both ends are fixed and limited pipe rotation is assumed. The loop is also geometrically similar with the middle parallel leg equal to ½ of each of the tangential legs. L = X + 2Y= (
DE/C1SA) 0.5
(Metric Units)
Where: L = loop length to accommodate thermal expansion, mm (ft); X = parallel leg of loop, mm (ft); Y = 2X = tangential leg of loop, mm (ft); D = actual outside pipe diameter, mm (in.); E = modulus of elasticity at the working temperature, kPa (psi); SA = maximum allowable stress at the working temperature, kPa (psi); = change in length due to temperature change, mm (in.) and C1 = constant = 0.3333. Code states that for the commonly used A53 Grade B seamless or electric resistance welded (ERW) pipe, an allowable stress SA of 155 MPa (22,500 psi) can be used without overstressing the pipe. However, this may result in very high-end reactions and anchor forces, especially with large diameter pipe. Designing to a stress range SA= 103 MPa (15,000 psi) and assuming E = 1.92 × 105 MPa (27.9 × 106 psi), the above equation reduces to: L = 74.7(
D) 0.5
(Metric Units)
This provides reasonably low-end reactions without requiring too much extra pipe. In addition, this equation may be used with A53 butt-welded pipe. When welded fittings are used in expansion loops rather than pipe bends, another important consideration is the effects of bending on the fittings used to install the expansion loop. The loop should be installed in consultation with the fitting manufacturer to ensure that specified fittings are capable of withstanding the anticipated loading conditions, constant and cyclic, at the design temperatures of the system. Terminal loadings on equipment determined from this analysis can then be used to assess the equipment capabilities for withstanding the loading from the piping system. It should also be noted that this termination analysis at equipment and anchor terminations should consider the movement and stress impacts of the “cold” condition.
Fig: Expansion Loop
Example 1: 145-m-long (475-ft-long) steel, 200-mm (8-in.) diameter liquid process pipe operates at 90°C (194°F) and 1.55 MPa (225 psig). The expansion caused by the process stream must be absorbed using U-bends without damage to the pipe. Solution: Step 1: Establish a temperature differential ( T). Assume an installation temperature of 4.4°C (40°F). This would be a conservative, yet reasonable, assumption. Therefore, the temperature differential would be 90°C – 4.4°C, or 85.6°C (194°F – 40°F, or 154°F). Step 2: Determine the thermal expansion ( ). =
L0 (
T)
Where: = thermal expansion of pipe run, mm (in.); = coefficient of thermal expansion, 11.7 × -6 -6 10 mm/(mm °C), (6.5 × 10 in./[in. °F]); L0 = original length of pipe run, mm (in.); T = temperature differential; = 11.7 × 10-6 mm/(mm °C) × 145,000 mm × 85.6°C (6.5 × 106 in./(in. °F) × 5700 in × 154°F). = 145.2 mm (5.71 in.) Step 3: Determine dimensions of expansion loop. The expansion loop is centred between anchored supports as schematically shown in Figure 2- 3d. L = X + 2Y= 74.7(
D) 0.5
OR
6.225 (
D) 0.5
And Y = 2X So’ L = 5X= 74.7(145.2 mm × 220 mm) 0.5 OR 6.225 (5.71 in. × 8.625 in.) 0.5 L = 5X= 13,351 mm (43.7 ft) X = 2670 mm (8.74 ft) Y = 2(2670 mm) = 5340 mm (17.5 ft) The length of the parallel leg of the expansion loop is 2670 mm (8.74 ft), and the length of each of the two tangential legs of the expansion loop is 5340 mm (17.5 ft). Installation of the Expansion Joint or U-Loop Pipe Compensator: It is important that expansion joints be installed at the proper length. They must never be stretched to make up deficiencies in pipe length or distorted to accommodate piping, which is not properly aligned at the time of installation. Cold Pull of the Expansion Joint or U-Loop Pipe Compensator: As in springs, bellow, expansion joints are suitable for both compression and extension from the natural free position. Up to 50% cold pull can be achieved by pre-setting the bellows prior to installation. Selection of the Expansion Joint or U-Loop Pipe Compensator: The following factors are to be taken into consideration in choosing correct expansion joint (I) pressure (ii) axial movement (iii) lateral movement (iv) angular rotation (v) temperature (vi) special service (vii) special corrosion problem. Full details are given in the selection chart. (vi) Bends & Mitre bends: All mitre bends shall be designed as per ANSI B 31.3 requirement. However, it can be fabricated from the straight pipe as per figure. Long radii welding elbows shall be used for changes in direction of piping. For steam and feed piping coming under the purview of the Indian Boiler Regulation bend radii shall be as per that regulations. Short radii bends shall only be used where space does not permit the use of long radii elbows and bends.
Fig: Mitre Bend of 5 Pieces & 4 Weld Welded mitre bends, with a maximum angle of 22.5
per segment, may be used in utility piping
systems for piping 6” NB and over, where the pressure and temperature does not exceed 7 Kg./cm2and 95 C respectively. In other services & higher-pressure conditions, the welded mitre bends may be used provided they meet process requirements. (vii) Branch connections: Branch connection has to be designed as per ANSI B 31.3 or RP 14E requirement and Appendix ‘H’ requirements or other applicable code requirements. However, all branches can also be designed as per pressure-temperature rating or piping material specification given in the book. Standard Branch Connection Schedule is given below: Reinforcement of Branch connection: This is used for straight run pipes as well as for branch connections. On Straight Pipe: If a butt-weld joining two sections of straight pipe is subject to unusual external stress, it may be reinforced by addition of a sleeve, which is a pipe cut at the seams in two parts. The Code applicable to piping should be referred for reinforcement. Reinforcing pieces are usually provided with a small hole to vent gases produced by welding, which would otherwise get trapped. A vent hole also serves to indicate any leak in the weld. On Branch Connections: It is addition of extra metal at a branch connection made from a pipe or vessel wall. The added metal compensates for structural weakening due to the hole. Stub-Ins may be reinforced with regular or wrap-around saddles. Rings made from pipe stock are used to reinforce branches made with welded laterals and butt-welded connections to vessels. Adding extra metal to the joint may reinforce small welded connections. Table: Branch Connection Schedule for Welded Piping Nom. Branch. Size (Inch) ½ ¾ 1 1½ 2 3 4 6
Nominal RUN Size (Inch)
½ ¾ sw sw sw
Nom. Branch. Size (Inch)
1 sw sw sw
1½ sw sw sw sw
2 SC SL SL TR T
3 SC SC SL SL TR T
4 SC SC SC SL TR TR T
6 SC SC SC SC W TR TR T
Nominal RUN Size (Inch)
8
10
12
14
16
18
8 10 12 14 16 18
T
TR T
TR TR T
TR TR TR T
TR TR TR TR T
W TR TR TR TR T
Legend T - Straight Tee (Butt-Welded) TR - Reducing Tee (butt-Welded) SC - 600# Socket Weld Forged Coupling SL - 600# Sockolet W - Weldolet (Schedule of Branch Pipe) SW - socket weld (viii) Pipeline: Pipeline is the piping system that is used for transportation of goods through a pipe. Most commonly, liquids and gases are sent, but pneumatic tubes that transport solid capsules using compressed air are also used. Any chemically stable substance can be sent through a pipeline. Therefore sewage, slurry, water, or even beer pipelines exist; but arguably the most valuable are those transporting petroleum products like, oil or oil product, natural gas or gas product, or bio fuels. Pipeline Components: Pipeline networks are composed of several equipments that operate together to move products from location to location. The main elements of a pipeline system are: i) Initial injection station: Initial injection station is the beginning of the system, where the product is injected into the pipeline. Initial injection station has storage facilities, pumps or compressors located at these locations. ii) Compressor/pump stations: Pumps for liquid pipelines and Compressors for gas pipelines are located along the line to move the product through the pipeline. iii) Partial delivery station: Partial delivery stations allow the pipeline operator to deliver part of the product being transported. iv) Block valve station: Block valve stations are the first line of protection for pipelines. With these valves the operator can isolate any segment of the line for maintenance work or isolate a rupture or leak. It is a very usual practice in liquid pipelines that block valve stations are usually located every 20 to 30 miles (48 km), depending on the type of pipeline, even though it is not a design rule. The location of these stations depends exclusively on the nature of the product being transported, the trajectory of the pipeline and/or the operational conditions of the line. v) Regulator station: Regulator stations are special type of valve station, where the operator can release some of the pressure from the line. Regulators are usually located at the downhill side of a peak. vi) Final delivery station: Final delivery station is also known as outlet stations or terminals, where the product will be distributed to the consumer. It could be a tank terminal for liquid pipelines or a connection to a distribution network for gas pipelines. Pigging of Pipeline: Pig is named on the basis of squealing sound they make while travelling through a pipeline. 'PIG' is an acronym or backronym derived from the initial letters of the term 'Pipeline Inspection Gauge' or possibly 'Pipeline Inspection Gizmo' or 'Pipeline Internal Geometry' or 'Pipeline Inspection Gadget'.
Pigging in the pipelines refers to the practice of using pipeline inspection gauges or 'pigs' to perform various maintenance operations on a pipeline. This is done without stopping the flow of the product in the pipeline. These operations include but are not limited to cleaning and inspecting of the pipeline. This is accomplished by inserting the pig into a 'pig launcher' (‘launching station') of a funnel shaped Y section in the pipeline. The launcher / launching station is then closed and the pressure driven flow of the product in the pipeline is used to push it along down the pipe until it reaches to the trap or the 'pig catcher' in the receiving station. If the pipeline contains butterfly valves, the pipeline cannot be pigged. Ball valves cause no problems because the inside diameter of the full bore ball valves can be specified to be the same as that of the pipe. Pigging can be used for almost any section of the transfer process between blending, storage or filling systems. Pigging systems are already installed in industries handling products as diverse as lubricating oils, paints, chemicals, toiletries, cosmetics and foodstuffs. Pigs are used in lube oil or painting blending to clean the pipes to avoid cross-contamination, and to empty the pipes into the product tanks or sometimes to send a component back to its tank. Usually pigging is done at the beginning and at the end of each batch, but sometimes it is done in the midst of a batch, e.g. when producing a premix that will be used as an intermediate component. Pigs are also used in oil and gas pipelines to clean the pipes but also there are "smart pigs" used to measure things like pipe thickness and corrosion along the pipeline. They usually do not interrupt production, though some product can be lost when the pig is extracted. They can also be used to separate different products in a multi-product pipeline. Pigging in production environments Advantage of Pigging: (i) Product and time saving: A major advantage of pigging systems is the potential resulting product savings. At the end of each product transfer, it is possible to clear out the entire line contents with the pig, either forward towards the receipt point, or backwards to the source tank. (ii) No requirement for extensive line flushing: Without the need for line flushing, pigging offers the additional advantage of a much more rapid and reliable product changeover. Product sampling at the receipt point becomes faster because the interface between products is very clear, and the old method of checking at intervals, until the product is on-specification, is considerably shortened. (iii) Environmental issues: Pigging has a significant role to play in reducing the environmental impact of batch operations. Traditionally, the only way that an operator of a batch process could ensure a product was completely cleared from a line was to flush the line with a cleaning agent such as water or a solvent or even the next product. This cleaning agent then had to be subjected to effluent treatment or solvent recovery. If product was used to clear the line, the contaminated finished product was downgraded or dumped. In some cases, the finished product could contain polychlorinated biphenyl (PCB), which has been found to be carcinogenic. All of these problems can now be eliminated due to the very precise interface produced by modern pigging systems. (iv) Safety considerations: Pigging systems are designed so that the pig is loaded into the launcher, which is pressured up to launch the pig into the pipeline through a kicker line. In some cases, the pig is removed from the pipeline via the receiver at the end of each run. All systems must allow for the receipt of pigs at the launcher, as blockages in the pipeline may require the pigs to be pushed back to the launcher. Most of the time, systems are designed to pig the pipeline in either direction. Pigging Operation: The pig is pushed either with an inert gas or a liquid; if pushed by gas, some systems can be adapted in the gas inlet in order to ensure pig's constant speed, whatever the pressure drop is. The pigs must be removed, as many pigs are rented, pigs wear and must be replaced, and
cleaning pigs push contaminants from the pipeline such as wax, foreign objects, hydrates, etc., which must be removed from the pipeline. There are inherent risks in opening the barrel to atmosphere and care must be taken to ensure that the barrel is depressurized prior to opening. If the barrel is not completely depressurized, the pig can be ejected from the barrel and operators have been severely injured when standing in front of an open pig door. When the product is sour, the barrel should be evacuated to a flare system where the sour gas is burnt. Operators should be wearing a self-contained breathing apparatus when working on sour systems. A few pigging systems utilize a "captive pig", and the pipeline is only opened up very occasionally to check the condition of the pig. At all other times, the pig is shuttled up and down the pipeline at the end of each transfer, and the pipeline itself is never opened up during process operation. These systems are not common. Intelligent pigging: Modern intelligent pigs are highly sophisticated instruments that vary in technology and complexity by the intended use and by manufacturer. An intelligent pig, or smart pig, includes electronics and sensors that collect various forms of data during the trip through the pipeline. The electronics are sealed to prevent leakage of the pipeline product into the electronics since products can range from highly basic to highly acidic and can be of extremely high temperature. Many pigs use specific materials according to the product in the pipeline. Power for the electronics is provided by onboard batteries which are also sealed. Data recording may be by various means ranging from analogue tape, digital tape, or solid state memory in more modern digital units. Inspection Pigging: The technology used to accomplish the service varies by the service required and the design of the pig. Surface pitting and corrosion, as well as cracks and weld defects in steel/ferrous pipelines are often detected using magnetic flux leakage (MFL) pigs. Other "smart" pigs use electromagnetic acoustic transducers to detect pipe defects. Calliper pigs can measure the "roundness" of the pipeline to determine areas of crushing or other deformations. Some smart pigs can combine technologies such as MFL and Calliper into a single tool. Recent trials of pigs using acoustic resonance technology have been reported for inspection purpose. During the pigging run the pig is unable to directly communicate with the outside world due to the distance underground or underwater and/or materials that the pipe is made of. For example, steel pipelines effectively prevent any reliable radio communications outside the pipe. It is therefore necessary that the pig use internal means to record its own movement during the trip. This may be done by gyroscope-assisted tilt sensors, odometers and other technologies. The pig will record this positional data so that the distance it moves along with any bends can be interpreted later to determine the exact path taken. Location verification is often accomplished by surface instruments that record the pig’s passage by either audible or galvanometric (or other) means. The sensors will record when they detect passage of the pig; this is then compared to the internal record for verification or adjustment. The external sensors may have GPS capability to assist in their location or even to transmit the pig’s passage, but the pig itself usually cannot use GPS as it requires being able to receive the satellite signals. After the pigging run has been completed, the positional data is combined with the pipeline evaluation data (corrosion, cracks) to provide a location-specific defect map and characterization. In other words, the combined data will tell the operator the location and type and size of each pipe defect. This is used to judge the severity of the defect and help repair crews locate and repair the defect quickly without having to dig up excessive amounts of pipeline. By evaluating the rate of change of a particular defect over several years, proactive plans can be made to repair the pipeline before any leakage or environmental damage occurs. A pipeline inspection gauge or "PIG" in the pipeline industry is a tool that is sent down a pipeline through a “Pig” launcher/receiver and propelled by the pressure of the product in the pipeline itself.
There are four main uses for pigs: (i) Physical separation between different liquids being transported in pipelines; (ii) Internal cleaning of pipelines; (iii) Inspection of the condition of pipeline walls (also known as an Inline Inspection (ILI) tool); and (iv) Capturing and recording geometric information relating to pipelines (e.g. size, position). Material of Pig: The original pigs were made from straw wrapped in wire used for cleaning. They made a squealing noise while travelling through the pipe, sounding to some like a pig squealing. The term "pipeline inspection gauge" was later created as a backronym. One kind of pig is a soft, bullet shaped polyurethane foam plug that is forced through pipelines to separate products to reduce mixing. There are several types of pigs for cleaning. Some have tungsten studs or abrasive wire mesh on the outside to cut rust, scale, or paraffin deposits off the inside of the pipe. Others are plain plastic covered polyurethane. Inline inspection pigs use various methods for inspecting a pipeline. A sizing pig uses one (or more) notched round metal plates that are used as gauges. The notches allow different parts of the plate to bend when a bore restriction is encountered. More complex systems exist for inspecting various aspects of the pipeline. Intelligent pigs, also called smart pigs, are used to inspect the pipeline with sensors and record the data for later analysis. These pigs use technologies such as MFL and ultrasonic to inspect the pipeline. Intelligent pigs may also use callipers to measure the inside geometry of the pipeline. The first intelligent pig was run to demonstrate that a self-contained electronic instrument could traverse a pipe line while measuring and recording wall thickness. The instrument used electromagnetic fields to sense wall integrity. It used MFL technology to inspect the bottom portion of the pipeline. The system used a black box similar to those used on aircraft to record the information. Capacitive sensor probes are used in the process of detecting defects in polyethylene pipe gas pipeline. These probes are attached to the pig in which the pig is sent through the polyethylene pipe that will detect any defects in the outside of the pipe wall. This is done by using triple plate capacitive sensors in which the electrostatic waves are propagated outward through the pipe's wall. Any change in dielectric material will result in a change in capacitance. (ix) Piping Supports: Piping should be supported on racks, stanchions or individual standoffs. The location and design of supports are dependent upon routing, media, weight, diameter, shock-loads, vibration, etc. Consideration should also be given to seal welding to minimize corrosion; providing sufficient clearance to permit painting and installing doublers (additional metal) under clamps and saddles. Valve supports should not interfere with removal of the valve for repair or replacement. See RP 14E and ANSI B31.3 for a discussion of piping flexibility and support requirements. (x) Unlisted Component: These piping components which are not listed anywhere in any code or standard, shall be designed based on design criteria of the code ANSI B31.3, considering all conditions of the piping design mentioned above. Experimental stress analysis as described in boiler and pressure vessel code section VIII, Division 2, Appendix 6 and proof test in accordance with ASME B16.9 or MSS-SP-97 or BH PV – section VIII, division 1, UG-101 shall be done. Also detailed stress analysis (finite element method) with result evaluated as per section VIII, division 2, appendix 4, and article 4-1 shall be done. After the design, the designer must interpolate between sizes, wall thickness and pressure classes and must determine analogies among related materials (xi) Gaskets: Gaskets are used for sealing of flange joints. A wide variety of gasket materials are available including different metallic and elastomeric products. Two primary parameters are considered, sealing force and compatibility. Gasket manufacturers supply the force that is required at this interface. Leakage will occur unless the gasket fills into and seals off all imperfections. The
metallic or elastomeric material used is compatible with all corrosive liquid or material to be contacted and is resistant to temperature degradation. For raised face flanges, spiral wound asbestos gaskets with stainless steel windings should be used because of their strength and sealing ability. For flat face ductile or cast iron valves used in water service, full face compressed asbestos gaskets are used. If less than full-face gaskets are used, flanges may break when flange bolts are tightened. Ring gaskets for RTJ flanges are made of soft iron, low-carbon steel, and stainless steel and are made in either an octagonal or oval cross-section. Hardness of metallic RTJ gasket should be in accordance with the value given below: Table: Gasket Materials Requirements Standard
Material
UP to 24” B16.21 UP to 24” B16.21 UP to 24” B16.21 24” & above API 605 24” & above API 605
Soft Iron
Maximum Hardness (BHN) 90
Face Finish
32 to 63 AARH
Low Carbon 120 Steel 5 Cr, 0.5 Mo 130
Same
SS 304, 316 & 140 347 SS 304L, 316L 120
Same
Same
Same
Types of Gaskets: Various types of gaskets are Non-Metallic Gaskets (ASME B 16.21); SpiralWound Gaskets (ASME B 16.20); Ring Joint Gaskets (ASME B 16.20). Non-Metallic Gaskets are used with flat face or raised face flanges. Spiral-Wound Gaskets are used with raised face flanges. They are available with an inner ring and outer ring, which is also known as the cantering ring. Ring Joint Gaskets are used with Ring Type Joint (RTJ) flanges. They are available in octagonal or oval cross sections. A very high surface stress is developed between an RTJ gasket and the flange groove when RTJ is bolted up in a flange. This leads to plastic deformation of the gasket. Thus, the hardness of the gasket is kept less than the hardness of the groove to achieve coining i.e. bringing two metal surfaces of different hardness so tightly together that the softer surface deforms to match harder surface exactly in shape and finish. The compression depends upon the bolt loading before internal pressure is applied. Typically, gasket compressions for steel raised-face flanges range from 28 to 43 times the working pressure in classes 150 to 400, and 11 to 28 times in classes 600 to 2,500 with an assumed bolt stress of 414 MPa (60,000 psi). Initial compressions typically used for other gasket materials are listed in Table below. Table: Gasket Compression Gasket Material Soft Rubber
Initial Compression, MPa (psi) 27.6 to 41.4 (4,000 to 6,000)
Laminated Asbestos 82.7 to 124 (12,000 to 18,000) Composition 207 (30,000) Metal Gaskets 207 to 414 (30,000 to 60,000) Note: These guidelines are generally accepted practices. Designs conform to manufacturer’s recommendations. Source: SAIC, 1998
In addition to initial compression, a residual compression value, after internal pressure is applied, is required to maintain the seal. A minimum residual gasket compression of 4 to 6 times the working pressure is standard practice. Table: Gasket Factors and Seating Stress Gasket Material
Gasket Factor, m Self-energizing types (o-rings, 0 metallic, elastomeric) Elastomeric with asbestos fabric insertion (with or without wire 2.25 reinforcement 2.50 3-ply 2.75 2-ply 1-ply Spiral-wound metal with 2.50 asbestos filled 3.00 Carbon Stainless steel, Monel and nickelbased alloys Corrugated metal jacketed with 2.50 asbestos filled 2.75 Soft aluminium 3.00 Soft copper or brass 3.25 Iron or soft steel 3.50 Monel or 4% to 6% chrome Stainless steels and nickel-based alloys Corrugated metal 2.75 Soft aluminium 3.00 Soft copper or brass 3.25 Iron or soft steel 3.50 Monel or 4% to 6% chrome Stainless steels and nickel-based 3.75
Minimum Design Seating Stress, y, MPa (psi) 0 (0)
15.2 (2,200) 20.0 (2,900) 25.5 (3,700)
68.9 (10,000) 68.9 (10,000)
20.0 (2,900) 25.5 (3,700) 31.0 (4,500) 37.9 (5,500) 44.8 (6,500)
25.5 (3,700) 31.0 (4,500) 37.9 (5,500) 44.8 (6,500) 52.4 (7,600)
alloys Ring joint 5.50 124 (18,000) Iron or soft steel 6.00 150 (21,800) Monel or 4% to 6% chrome 179 (26,000) Stainless steels and nickel-based 6.50 alloys Notes: Refer ASME Section VIII, Appendix 2, for us of gaskets (xii) Fasteners (Bolt, Nut & Washer): Fasteners join or affix two or more pipes together. Pipe fasteners cover high tensile and mild steel bolts, clamps, nuts, screws, washers, studs, pins etc. All types of fasteners are used for both industrial pipe fittings. Pipe fasteners are used in almost all types of industries. They are made of various materials and are available in various shapes, sizes and designs. APPLICABLE CODE: ASTM A193: AS and Stainless Steel bolting materials for HighTemperature Service ASTM A194: AS and Stainless Steel Nuts for bolts for HighTemperature Service ASTM A307: Carbon Steel Bolts and Studs, 60000-PSI Strength ASTM A320: Alloy Steel Bolting Materials for Low-Temperature Service ASTM A325: Structural Steel Bolts, Heat-treated, 120/125 Ksi minimum UTS ASTM A354: Specification for Quenched and Tempered Alloy Steel Bolts, Studs. ASTM A437: AS Bolting Materials Specially Heat Treated for HighTemperature Service ASTM A540: Alloy Steel bolting materials for Special Application
Fasteners are used widely for fastening and fixing various construction Pipe Flanges. Fasteners include Studs. Studs are used in fastening various products, including pipes used in different applications. These types of fasteners are threaded on one or both ends. Studs are headless bolts, threaded, sometimes with different threads. Both ends of the stud are secured to an object with nuts. They are available in both Metric and English threads. Stud Fasteners are available in all forms to suit any application. Suds have Good strength; Reasonable cold ductility; excellent high temperature ductility; Good conductivity; excellent corrosion resistance; Good bearing properties; and Low magnetic permeability.
Advantages of studs: Studs help in reducing assembly costs. They permit quick and easy "stack up" of gaskets or other different parts of a joint or two different pipes. Studs also help in reducing the need for the large whole clearance and close whole alignment which are usually required by a bolt. Studs with an interference-fit thread or proprietary-lock thread on the tap or pipe end gives a positive lock against turning and loosening. Studs also provide sealant to prevent leakage of fluids through holes tapped in porous materials. Bolts: Bolts are used as threaded fastener, with a head, designed to be used with a nut. Bolts are a sensible and easy way of securing piping, tubes and hoses in all industrial applications. They are designed to be used for mounting of pipes to the walls or fastening piping components. Hexagonal Bolts can come fully or partially threaded depending on the bolt type. A grade 8 bolt is stronger than the more commonly used grade 5. It is made of alloy steel and has six radial lines on the top of the bolt head. Grade 8 bolts have a tensile strength of 150,000 pounds per square inch. We recommend using grade 8 nuts, flat washers and high alloy lock washers with any grade 8 bolts / hex cap screws. Threads will vary according to the individual bolt sizes and dimensions. Table: Bolts and Nuts’ Grade and Composition: CHEMICAL COMPOSITION OF STEEL BOLTING FOR HIGH TEMPERATURE SERVICE - I ASTM A 193 Ferritic Steels C Mn SI Cr B5
0.10
1.00
1.0
4.00-6.00 11.50B 6, B 6X 0.15 1.00 1.0 13.50 B7, B 7M 0.37-0.49 0.65-1.10 0.15-0.35 0.75-1.20 B16 0.36-0.47 0.45-0.70 0.15-0.35 0.80-1.15 Austenitic Steels 18.00B 8, B 8A 0.08 2.00 1.0 20.00 17.00B 8C, B 8CA 0.08 2.00 1.0 19.00 B 8M, B 8MA 16.00B 8M2, B 0.08 2.00 1.00 18.00 8M3 18.00B 8N, B 8NA 0.08 2.00 1.00 20.00 B 8MN, 16.00B 8MNA 0.08 2.00 1.00 18.00 17.00B 8P, B 8PA 0.08 2.00 1.00 19.00 19.50-
B 8MLCuN B 8MLCuNA
0.020
1.00
0.80
B 8T, B 8TA
0.08
2.00
1.00
B 8R, B 8RA
0.06
4.00-6.00
1.00
B 8S, B 8SA B 8LN, B 8LNA B 8MLN, B 8MLNA
0.10
20.50 17.0019.00 20.5023.50
7.00-9.00 3.50-4.50
0.30
2.00
1.00
0.30
2.00
1.00
16.0018.00 18.0020.00 16.0018.00
CHEMICAL COMPOSITION OF STEEL BOLTING FOR HIGH TEMPERATURE SERVICE - II ASTM A 193 Ferritic Steels Ni Mo Others B5 B 6, B 6X B7, B 7M B16 B 8, B 8A B 8C, B 8CA B 8M, B 8MA B 8M2, B 8M3 B 8N, B 8NA B 8MN, B 8MNA B 8P, B 8PA B 8MLCuN
---------
0.40-0.65 --0.15-0.25 0.50-0.65
------0.25-0.35 V
8.00-10.50
---
---
9.00-13.00
---
Cb=10 X Cc
10.00-14.00
2-00-3.00
---
8.00-10.50
---
0.10-0.16 N
10.00-14.00
2.00-3.00
0.10-0.16 N
10.50-13.00
---
17.50-18.50
6.00-6.50
--0.18-0.22 N, 0.50 - 1.00 Cu
B 8MLCuNA B 8T, B 8TA 9.00-12.00 B 8R, B 8RA 11.50-13.50 B 8S, B 8SA 8.00-9.00 B 8LN, B 8LNA 8.00-10.50 B 8MLN, B 8MLNA 10.00-14.00
--1.50-3.00
Ti = 5 X Cc 0.20-0.40 N, 0.10-0.30 V, 0.10-0.30 Cb+Ta
---
0.08-0.18 N
---
0.10-0.16 N
2.00-3.00
0.10-0.16 N
Nuts: Nuts are very useful to attach machine thread fasteners. Nuts are widely used as pipe fasteners. In-fact no bolts can be fixed to a pipe without the use of nuts. Bolts and nuts are used in combination. Washers: A washer is a type of thin disk with a hole, usually in the centre. A washer is used to support the load of a threaded fastener. It can also be used as a spacer, spring, wear pad, pre-load indicating device, and also locking device. In taps or valves, it is used to form the seal that shuts off the flow of liquid or gas. There is a type of washer called the reducing washer which is used to connect pipes of different sizes. Washers are available in various sizes and materials and widely used in pipe applications besides the other applications. Lock Washers, also known as split washer, and provide better load distribution and greater tension which in turn prevent against loosening due to vibration. Flat Washers are used for a truly non-corrosive assembly. Spring Washers are adjustable washers in an irregular shape so that when the washer is loaded it deflects and acts like a spring, which in turn provide a pre-load between two surfaces. (xiii) Pipe Clamps: The pipe clamps are special type of fasteners suitable for clamping pipes and hoses. Pipe clamps are a sensible and easy way of securing piping, tubes and hoses in all types of terrestrial or naval installation. Some pipe clamps can also be mounted on piping components other than straight pipe. The pipe clamps are sometimes controlled by pressure activated cylinders to regulate the clamping pressure in relationship to the thickness and strength of the pipe wall. Pipe clamps have one fixed pad, and one adjustable pad. Pipe clamps are constructed using various materials and are available in several configurations. Metallic pipe clamps have high impact resistance with heat-resistant coatings and epoxy coatings. Pipe clamps are designed for a wide range of fastening applications. These clamps are ideal for suspension of cold or hot pipe lines with heavy load having little or no insulation. They are also used for high and even tightening force around the pipe, minimizes leakage. The pipe clamps absorb shock, dampen vibration, and reduce noise in plumbing systems. They can be used in high temperature applications. (xiv) Fire Protection Services: Fire protection services install, maintain and monitor safety equipment such as flame and smoke detectors, sprinkler systems, fire alarms and enunciators. Flame detectors are used by fire protection services to determine whether a fuel is burning, or if ignition has been lost. Smoke detectors or smoke alarms detect airborne smoke and issue audible alarms. Like flame detectors, they also send signals to fire protection services. Sprinkler systems are fire protection devices which consist of overhead pipes fitted with sprinkler heads. Heat-sensitive seals
prevent the flow of water until a threshold temperature is exceeded. Fire alarm services then dispatch emergency personnel to a customer’s location. At larger facilities, fire protection services are alerted by fire enunciators, electronic systems which fit into a standard electrical box and provide visual outputs with light emitting diodes (LEDs). a) Flame Arrester: Flame Arresters is a safety device that stops fuel combustion by extinguishing the flame. A flame arrester functions by forcing a flame front through channels too narrow to permit the continuance of a flame. These passages can be regular, like wire mesh or a sheet metal plate with punched holes, or irregular, such as those in random packing. The required size of the channels needed to stop the flame front can vary significantly, depending on the flammability of the fuel mixture. The large openings on a chain link fence are capable of stopping the spread of a small, slowburning grass fire, but fast-burning grass fires will penetrate the fence unless the holes are very small. Detonation Flame Arresters prevents propagation of detonations in gas or vapour mixtures in piping system or a pipeline with a significant distance between the ignition source and the arrester, or in a rough, bent, obstructed or having section changed piping. A detonation flame arrester contains a crimped ribbon element with small apertures which allows gas or vapour to pass. The elements are designed so that they both attenuate the detonation shock wave, and extinguish the flame. If the apertures are smaller than the maximum experimental safe gap (MESG) for the gas or vapour then a flame cannot pass through the arrester, and is subsequently contained or extinguished. Flame Arrester protects systems for generating, storing, transporting of gases and liquids of every hazard category against dangers such as endurance burning, deflagration and detonation. Deflagration Flame Arrester: A Deflagration Flame Arrester is an explosive combustion process in which the flames propagate at subsonic velocity. Deflagration Flame Arrester avoids flame propagation from outside (atmosphere) to inside of systems e. g. storage tanks, vessels or in process plants a flame arrester at end of vent line has to be installed. It protects the impact of atmospheric deflagration and prevents flame transmission to protect equipment. These flame arresters are not tested for short time or endurance burning. Deflagration Flame Arresters are designed to prevent the transmission of a deflagration as they are fitted with one pipe connection on one side of the flame arrester element. b) Flame detectors: Flame detectors monitor and analyze incoming radiation at selected wavelengths. Flame detectors use optical sensors working at specific spectral ranges to record the incoming radiation at the selected wavelengths. 30 - 40% of the energy radiated from a fire is electromagnetic radiation that can be read at various spectral ranges (such as UV, VIS, IR). The signals are then analyzed using a predetermined technique (flickering frequency, threshold energy signal comparison, mathematical correlation between several signals, correlation to memorized spectral analysis). Flame detectors are available in a number of sensor types. The most common sensor types include UV detectors, IR detectors, UV/IR detectors, IR/IR detectors, and IR^3 (triple IR) detectors, and triple IR spectral band detectors. c) Smoke Detectors: Smoke detectors are designed to sense the products of combustion. Common types include ionization chambers and photoelectric devices. Smoke detectors are designed to sense the products of combustion. Smoke detectors include a sensor and detector circuitry. They usually contain a built-in alarm, may instead provide electrical contacts for an auxiliary alarm. Smoke detection systems are networked, programmable products that include a control unit and detector. Individual smoke detection components are also commonly available. Smoke detectors with an IC form factor are semiconductor devices that are designed for smoke-sensing applications. They do not contain an actual smoke sensor, and may be suitable for AC or DC – but not both. Addressable smoke
detectors are fire detection products that communicate with each other in a networked system.
6 Piping Project Management 6.1
Project Introduction
A project management is a temporary endeavour undertaken to create a unique product or service. That means every project has a definite beginning and a definite end. That means the product or service is different in some distinguishing way from all other similar products or service. The example of the Project can be one of the followings: Construction of a building or facility. Development of a new product or service. Design of a new transportation vehicle. Construction of a bib Refinery Construction of complete Piping work in any one unit of the Refinery plant. Etc. All projects involve materials, manpower and equipments. Material schedules indicate about when the material is needed on the job. They may also show the sequence in which materials should be delivered. Equipment schedules coordinate all the equipment to be used on a project. They also show when it is to be used and the amount of time each piece of equipment is required to perform the work. Manpower schedules coordinate the manpower requirements of a project and show the number of personnel required for each activity. In addition, the number of personnel of each rating, i.e. Builder, Construction welder, Equipment Operator, fabricator, and Utilities man, required for each activity for each period of time may be shown. The time unit shown in a schedule should be some convenient interval, such as a day, a week, or a month. A project management mainly deals with scheduling of materials, manpower and equipments used for completion of the project.
6.2
Project Management
Project Management is the organizational approach and the application of knowledge, skills, tools, and techniques to project activities in order to meet or exceed stakeholders differing needs, i.e. Identified requirements and expectations, i. e. unidentified requirements from a project. Project Management is the computer-based management of the Project from basic concept till completion of the Project. This involves balancing competing demands among scope, time, cost, and quality. It is an art and it requires both powerful skills and structured management to make it more effective. Effective project management skills allow you to shorten the lead-time from concept to market, thereby maximizing your chances of meeting the needs of the customer. A successful management must meet several objectives. Each objective is made of many constraints that must be addressed. Project management is seen as a specialist discipline requiring special people. Projects, in the modern sense, are strategic management tools. It is no longer the preserve of specialists and the engineering sector, but an activity for everyone. This is a small write-up to give you basic knowledge and concept of project planning and management which enable you to handle the project effectively in organizations, introduce you to the modern trends in the project management and the entire concept behind it. The project management concepts or knowledge have been divided into many areas as described below: Project Scope Management: Project scope management describes the processes required to ensure that the project includes all the work required, and only the work required, to complete the project successfully. It consists of initiation, scope planning, scope definition, scope verification, and scope change control. Project Integration Management: Project integration management describes the processes required to ensure that the various elements of the project are properly co-coordinated. It includes of project plan development, project plan execution and overall change control. Project Time Management: Project time management describes the processes required to ensure that the project is completed in time. It consists of activity definition, activity sequencing, activity duration estimating, and schedule development and schedule control. Project Cost Management: Project cost management describes the processes required to ensure that the project is completed within the approved budget. It consists of resources planning, cost estimating, cost budgeting, and cost control. Project Quality Management: Project scope management describes the processes required to ensure that the project will satisfy the needs for which it was undertaken. It consists of quality planning, quality assurance, and quality control. Project Human Resource Management: Project human resource management describes the processes required to ensure the most effective use of the people involved with the project. It consists of organizational planning, staff acquisition, and team development. Project Communication Management: Project communication management describes the processes required to ensure the timely and appropriate generation, collection, dissemination, storage, and ultimate disposition of the project information. It consists of communication planning, information distribution, performance reporting, and administrative closure. Project Risk Management: Project risk management describes the processes required to ensure identifying, analyzing and responding to the project risk. It consists of risk identification, risk quantification, risk response development, and risk response control. Project Safety Management: Project safety management describes the processes required to ensure
that the project is completed safely with zero waste of man-hour with respect to accident, injury, and casualty. It consists of initiation of safety rules, safety planning, safety definition, safety verification, and safety control. Project Procurement Management: Project procurement management describes the processes required to acquire goods and services from outside performing organization. It consists of procurement planning, solicitation planning, sources selection, contract administration, and contract closeout. Project management is done with the help of computer software packages such as PRIMAVERA, OPEN PLAN, ARTEMIS, HOST, COSMOS AND INMOS, HOST, COSMOS, and INMOS developed by many electronic firms. The packages such as PRIMAVERA, OPEN PLAN & ARTEMIS are the “NETWORK ANALYSIS PACKAGES”. Salient features of the above packages are as below: Generates Schedules in Linked-Bar-Chart form. Display dependencies of Activities. Simultaneous existence of multiple schedules. Optional Bars, Symbols, or combination of both, presentation for the Activities. Standard symbols with user’s definable description for displaying different milestones. Provisions of assigning negative Timing (Work before Zero date). User’s friendly Menu driven software.
6.3
Network Analysis Package
Network analysis is a method of planning and controlling project by recording their interdependence in diagram form. This enables us to undertake each problem separately. The diagram form, known as a network diagram, is drawn so that each job is represented by an activity on the diagram. The direction in which the activities are linked indicates the dependencies of the jobs on each other. The Network Analysis Packages are used to integrate time, resources, and cost objectives into a workable plan. A project network diagram is a schematic display of the project activities and the logical relationships among them. A project network diagram may be produced manually or on a computer. A summary narrative that describes the basic sequencing approach should accompany the diagram. Any unusual sequences should be fully described. The project network diagram is often called a “PERT” Chart, i.e. Program Evaluation and Review Technique. A PERT chart is a specific type of project network diagram that is useful for a mega projects like Refineries, Petrochemicals plants etc. Planning and Scheduling are the two distinct functions in the Network Diagramming. Planning: Planning defines the activities involved in a project, their logical sequence and their inter relationship. Planning process also includes estimating the amount of time required to complete each activity. Scheduling: Scheduling places the activities in a workable timetable and Network. Network: The following four-standard concepts are used for preparation of Network: Arrow Diagramming Method (ADM): This is a method of constructing a project network diagramusing arrow to represent the activities and connecting them at nodes to show the dependencies. This represents activities with an arrow. The activity’s start and end points are called events and are represented by circles. The Events represents successive points in time and only one activity occurs between any two events. The ADM method is also called Activity-On-Arrow (AOA). Precedence Diagramming Method (PDM): This is a method of constructing a project network diagram using nodes to represent the activities and connecting them with an arrow. An Arrow shows the relationship between these activities. PDM Diagramming is more flexible than ADM because they can show several types of relationships between activities, such as, (1) Finish-to-start (FS) i.e. the “from” activity must finish before the “to” activity can start; (2) Start-to start (SS) i.e. the “from” activity must start before the “to” activity can start; (3) finish-to finish (FF) i.e. the “from” activity must finish before the “to” activity can finish; and start-to finish (SF) i.e. the “from” activity must start before the “to” activity can finish. PDM can be done manually or on software package. Conditional Diagramming Method: This method uses the Diagramming Techniques such as GERT, i.e. Graphical Evaluation and Review Technique or SDM, i.e. System Dynamics Models, to allow for non-sequential activities such as loops (e.g. a test that must be repeated more than once) or conditional branches (e.g. a design update that is only needed if the inspection detects errors). Neither PDM nor ADM allow loops or conditional branches. Network Templates: The standardized networks can be used to expedite the preparation of project network diagrams. They can include an entire project or only a portion of it. The portion of the network is often referred to as subnets or fragments. Subnets are especially useful where a project includes several identical or nearly identical features. In the Network, the logical sequence and relationships of the activities are defined after each activity in the project. The network Analysis calculates the early and late start and completion dates for each
activity using the forward pass and backward pass concept. The total and free float available with each activity is also calculated. The total float is the number of work periods that start and finish of an activity can be delayed without affecting the project completion date. Free float is the amount of time that activity’s early start can be delayed without delaying the early start of a successor activity. The Critical Activities control the overall timing of the project. The Critical Path, which can be more than one in the network, is a continuous chain of activities with Zero and Negative Total Float that makes the longest path of activities running from the starting event to the finishing event of the project. The network is updated at the regular intervals by reporting progress as of the data date and making any necessary changes in the network logic. The data represents the date up to which the progress is recorded, in the form of actual start and completion date of activities, percent of work completed and revised remaining duration etc. The network package, then, calculates the revised schedule for the activities in progress or not yet started to give a projected project Completion date or Schedule. Overall or Master Control Networks can be generated by using any one of the above computer packages. Followings are the reports generated through the network analysis packages: Time Scale Logic Diagram: It presents the overall logic of the project according to time. The activity Bars are depicted as rectangular boxes with their start and finish relative to the time scale. The connector lines show the relationship. The effect of lag is shown by the chronological placement of activities. Pure Logic Diagram: The pure logic diagram shows the relationships between activities of a project without consideration of time. The diagram starts with the first activity with no successor. The activity’s boxes contain the activity ID, description, original and remaining duration, total float, percent of completion, early and late dates, calendar codes and activity’s codes. The completed activities have a strike (X) through the box. Bar Chart: A Bar Chart or Gantt. Chart is a line graph that depicts the activities by rectangles with length proportional to the duration of each activity. The horizontal placement of the activity depends on the position in time. Generally, one activity bar is shown in one row. In a “linked bar chart” the relationship between the activities are also displayed on it. Schedule Reports: The Schedule Reports provide a tabular list of schedule data showing activity’s ID, descriptions, durations, float, early and late schedule dates. These reports consist of the followings: Activity checklist; Precedence/ Successor Report and Criticality Report.
6.4
Scheduling Technique
The above packages are used for effective scheduling and monitoring of all activities (deliverables like AFC Drawings, Material Requisitions, tendering, engineering, procurement, and construction etc. in line with the targets outlined in the overall project schedule. The schedules are developed in the form of Bar Charts and S-curves. It updates the status of all activities on a regular basis through activity turnaround documents, so as to monitor the actual progress of all the activities against the planned progress. It includes the identification of Milestones on which particular class of activities will be monitored. The progress attributed to individual milestone and the time taken for completing individual milestone is also provided by this package. The Weightage for individual activities in the form of “Budgeted Man-hours” based on the relative complexity of the activity and the scheduled effort to complete the same are taken into consideration as input. Scheduling is a mathematical analysis, which involves calculating theoretical early and late start and finish dates for all the project activities without regard for any resource pool limitations. The most widely used Scheduling Techniques are: Critical Path Method (CPM): Critical Path Method calculates a single, deterministic early and late start and finish date for each activity based on specified, sequential network logic and a single duration estimate. The focus of CPM is on calculating float in order to determine which activities have the least scheduling flexibility. Graphical Evaluation and Review Technique (GERT): Graphical Evaluation and Review Technique allows for probabilistic treatment of both network logic and activity duration estimates (i.e. some activities may not be performed at all, some may be performed only in part, and other may be performed more than once). Program Evaluation and Review Technique (PERT): Program Evaluation and Review Technique (PERT) uses sequential network logic and a weighted average duration estimate to calculate project duration. Although there are surface differences, PERT differs from CPM primarily in that it uses the distribution’s mean (expected value) instead of the most likely estimate originally used in CPM. PERT is seldom used today although PERT like estimates are often used in CPM calculations. Duration Compression: Duration Compression is a special case of mathematical analysis that looks for ways to shorten the project schedule without changing the project scope (e.g. to meet imposed dates or other schedule objectives). The following reports are generated as output for scheduling and monitoring of the project: Bar Charts: The bar charts are the functional schedules for Engineering, Procurements, Ordering, Manufacturing & Delay, and Tendering Schedules of all functional departments, which are generated as reports. The engineering bar charts are prepared at the work package level while the other schedules are prepared at the activity level. The schedule start & completion, man-hours and description of activities along with the bar representing the span of the activity on a time scale is shown in the bar chart. Options are available to print the progress distribution, man-hour equivalent, or the milestone occurrences of activities in the bar charts. S-Curves: The schedule and actual progress distribution of functional departments as well as the overall Engineering, Procurement and Tendering progress are generated through the above packages in the form of S-Curves in the X-Y co-ordinates where the X-axis represents the time span in months and Y-axis represents the percentage progress scheduled/achieved. Input Status Reports: The input turnaround document reflects the current status of all ending inputs
to various engineering activities. This report indicates the earliest requirement date and the latest date by which the item should be made available. Activity Status Reports: The complete status of all project activities is reflected in the Activity Status Reports. The report provides information about the description of activities, man-hour assigned, scheduled start, completion and schedule progress as on status date of all the activities. The detail of the milestones on which the activities will be monitored along with their scheduled achievement dates is provided in the reports. Activity List: The activity list lists out the activities, which are to be taken up as per the schedule. The activities are classified as “Backlog Activities” and “Current Activities”. All activities, which should have been completed now as per the schedule, but either not started or are in progress are classified as “Backlogs”. The activities to be taken up as per schedule are classified as “Current Activities”. The Activity Reports give the activities description, schedule date, scheduled and actual progress, current status of the activity and the Milestone, which is due. Summary Status Reports: The status of deliverables (AFCs, MRs, and Tenders) for each executing department is provided in the form of a summary report and the user selects the milestones for which summary report is required. The report gives the total numbers of activities, no. of activities to be completed as per schedule and the no. of activities actually completed. Progress Report: The progress report gives the scheduled and actual progress for individual executing department and the summary of the overall functional progress. Manpower Schedule: The manpower schedule gives the function wise manpower requirement over the total duration of the project. Details for departmental breakup (e.g. piping, piping supports, structural etc.) for each function is also given in the report. Characteristics of the Project Progress Life Cycle: The project progress life cycle defines the beginning and the end of the project with its profile of progress of the work in between these two activities as explained below by figure: COSMOS (Computerized Online System for Material Allocation at Site): This is a system for control of piping material at construction sites and is equally useful in both Single Project as well as Multi Project environment. This facilitates, (1) The tracking of material from Material Take off (MTO) stage to the actual consumption of piping materials, (2) Equitable and balanced allocation of piping material based on the priority fixed and work load at sites and (3) Timely feedback of any excess or unplanned issue of material.
Duration in months Fig: General Life Cycle of the construction Project with volume of work done STARS (Systematic Total Accounting and Record keeping for Stores): This package generates the following Reports, such as Reports based on all P.O.; Material Receiving Reports; Material Issue Voucher (MIV) reports for item wise; MIV reports for contractor’s discipline wise; MRV (Material Return Voucher) Reports; MRV reports for item wise; MRV reports for contractor’s discipline wise; Stock Status Reports and Bin Card Report for an item.. INMOS (Inspection Monitoring System): This package is designed for the monitoring the quality and the quality assurance of the piping work at site. It covers all the activities related to the piping work where radiography is required. This gives the following information on piping: (1) LINE MASTER- Line wise records such as Line Number, Line Responsibility Codes, Contractor’s name, Plant, Area, System, and Loop etc. Joint Master: Line wise Joints Records such as Joint Number, Piping Material Code, and joint Diameter, Joint Type, (Location, Fillet, Butt-Weld, Field Joint, Shop Joint.); Fit up Date; Welder Number and Date; D.P. Date and Bill Number (For Root and Final); Stress Relieving Chart Number, Date, and Bill No.; Radiography Details (Number, Result, Date, Repair, etc and Bill No.).
6.5
Project Monitoring System
The projects are executed every day but the progress is never achieved as per the planned schedule. The control and monitoring of the project is very necessary to meet the project completion as per planning. The monitoring and control of the project starts as soon as the project starts. The monitoring is the close watching of the progress. The main objective of project monitoring is to ensure the followings: a. The management objective of the Time and Cost are met. b. The various plans made for execution of the project are complied with. c. The Schedules are revised and updated to accommodate the changes arising out of unforeseen circumstances. Estimating: Material Estimate: A material estimate consists of a listing and description of the various materials and the quantities required to construct a given project. Information for preparing material estimates is obtained from the activity estimates, drawings, and specifications. A material estimate is sometimes referred to as “a Bill of Material (BM)” or “a Material Takeoff (MTO) Sheet.” Equipment Estimate: Equipment estimates are listings of the various types of equipment, the amount of time, and the number of pieces of equipment required to construct a given project. Information, such as that obtained from activity estimates, drawings, specifications, and an inspection of the site, provides the basis for preparing the equipment estimates. Manpower Estimate: The manpower estimate consists of a listing of the number of direct labour man-days required to complete the various activities of a specific project. These estimates may show only the man-days for each activity, or they may be in sufficient detail to list the number of man-days for each rating in each activity-Welder (W), Construction Fitter (CF), Equipment Operator (EO), Fabricator (F), and Gas Cutter (GC). Man-day estimates are used in determining the number of personnel and the ratings required on a deployment. They also provide the basis for scheduling manpower in relation to construction progress. A man-day is a unit of work performed by one person in one 8-hour day or its equivalent. In general, the work schedule of the group is based on an average of 54 hours per man per week. The duration of the workday is 8 hours per day, which starts and ends at the jobsite. This includes 8 hours for direct labour and 1 hour for lunch. Direct labour includes all labour expended directly on assigned construction tasks, either in the field or in the shop that contributes directly to the completion of the end product. Direct labour must be reported separately for each assigned construction item. In addition to direct labour, the estimator must also consider overhead labour and indirect labour. Overhead labour is considered productive labour that does not contribute directly or indirectly to the product. It includes all labour that must be performed regardless of the assigned mission. Indirect labour is required to support construction operations but does not, in itself, produce an end product. Documents: We, on completion of the work, give the documents to planning department for construction planning and scheduling of the project. There are two basic ground rules in analysing a project; planning and scheduling. These are two separate operations. Planning must always precede scheduling. If we don’t plan sequentially, we will end up with steps out of sequence and may substantially delay the project. Everyone concerned should know precisely the following aspects of a project: What it is; its start and finish points; its external factors, such as the schedule dates and requirements of other trade groups. The monitoring of the project is done by proper planning, which is developed by the planning
Engineer. The effective monitoring and control system involves the Weightage Estimate to monitor the following activities: Measuring the performance of work against plan. Identifying the deviations from plan while executing the work. Communicating the deviations to take remedial corrective action. Suggesting the corrective actions to alleviate and mitigate the deviations. Table: The overall Progress Reports of the project S.N.
Phase (Division)
Total Man- % Work completed hour Progress in Man-hour 1 Engineering X1 X2 X1 X2 2 Procurement Y1 Y2 Y1 Y2 3 Construction Z1 Z2 Z1 Z2 Total X1 + Y1 + X1 X2 + Y1 Y2 + Z1 Z1 Z2 Overall Progress = (X1 X2 + Y1 Y2 + Z1 Z2) / (X1 + Y1 + Z1) Review: The project implementation is usually carried out through 3-tier Monitoring and Review System: Weekly Review: The work progress of each contractor is reviewed at site on weekly basis by the Incharge of the project for assessing the work performance based on front available on activity level and to minimize slippage. Monthly Review: The project Managers monitor and review the work progress of each contractor at site with Client, Functional Heads and Co-coordinators for assessing the work performance based on front available on activity level and to minimize slippage. During the meeting, they review the project completion trends and progress, Executive Summary, Milestones Status, Delay Analysis, Functional Progress Curve, AFC Drawing Status, Equipments and Piping materials Receipt Status, major holdups and area of concerns etc. Corporate Review: Besides the above two reviews, the corporate Management reviews all major problems on quarterly basis where decision on strategies, work plan, allocation of resources are discussed for meeting the project requirements. The following Break-ups of the Weightage Value are used for proper monitoring of the project: Overall Percentage Break-up of Weight ages of the Project: 1. Process & Engineering : 8 – 12% 2. Procurement:i) Ordering : 3 – 5% ii) MFG. & Delivery : 50 – 55% 3. Construction : 25 – 30% 4. Commissioning : 3 – 5% Overall Percentage Break-up of Weightage of the Construction at site: 1. Site development : 5 – 8% 2. Civil & Structural work : 25 – 35% 3. Mechanical Work : 36 – 50% 4. Electrical Work : 6 – 10% 5. Instrumentation Work : 6 – 8%
6. Insulation and Painting Work : 4 – 6% Overall Percentage Break-up of Weightage of the Piping Work: 1. Contractor Mobilization at Site : 0 – 1% 2. Receipt of Materials at Site : 15-20% 3. Fabrication of Piping : 25- 30% 4. Erections and Assembly of Piping : 20 – 29% 5. Mechanical Completion of Piping : 1 – 3% 6. Testing of Piping : 5 –10% 7. Painting : 3-5% 8. Handing Over of Documents : 1-2%
6.6
Standard Man-hour for Piping
The basic principle involves assigning of Weightage for each activity to be performed at site on the basis or in term of standard man-hours after applying corrective factors to reflect the effort required. The first step to develop the estimate is to collect the required reference data as listed below: Plot Plan. P & I Diagrams, Piping Schedule, Drawing Schedule, Material Schedule, Bill of Materials, Master Project Schedule, Key Construction Network, Job Instructions, The man-hour estimate should cover all activities in involved in piping work. The development of man-hour estimate consists of availability of standard man-hour for each activity as given below: (i) Structural Steel: Fabrication : 180 Ton per month per Fabricator group. Erection : 100 Ton per month per Erecter up to 30 M level. Grating: Fabrication : 300 Ton per month per Fabricator up to 30 M level. Erection : 70 Ton per month per Erecter up to 30 M level.. (ii) Piping: (a) Under Ground (U/G) Piping: (Including excavation, fabrication & Erection of pipe, Coatingwrapping, laying and backfilling): a) C.S. Pipe : 20.0 Man-hour per Meter of 8.0” dia. average pipe size. b) Concrete Pipe : 16.0 Man-hour per Meter of 14.0” dia. average pipe size. c) Cast Iron Pipe : 19.0 Man-hour per Meter of 12.0” dia. average pipe size. d) PVC Piping : 16.0 Man-hour per Joint of 12.0” dia. average pipe size. (b) Above Ground (A/G) Unit piping: (one joint per 1.2 meter average of pipe length is taken for unit piping) Fabrication: CS Piping : 25.0 Inch-Dia. Per welder per day. AS Piping : 20.0 Inch-Dia. Per welder per day. SS Piping : 22.0 Inch-Dia. Per welder per day. Erection: CS Piping : 15.0 Inch-Dia. Per welder per day. AS Piping : 10.0 Inch-Dia. Per welder per day. SS Piping : 12.0 Inch-Dia. Per welder per day. A/G Unit Piping: (Total including cutting, edge preparation, grinding, welding, and inspection, supporting and testing, i.e. fabrication & erection both etc): a) C S Piping : 15.0 Man-hour per Meter of 3.0” x Sch. 40, average pipe size. : 5.0 Man-hour per Inch-Meter of 3.0” x Sch. 40, average pipe size. : 6.0 Man-hour per Inch-Dia. of 3.0” x Sch. 40, average pipe size. : 30 Inch-Dia. Per welder per day. b) A S Piping : 24.0 Man-hour per Meter of 3.0” x Sch. 40, average pipe size. : 7.0 Man-hour per Inch-Meter of 3.0” x Sch. 40, average pipe size.
: 8.5 Man-hour per Inch-Dia. of 3.0” x Sch. 40, average pipe size. : 20.0 Inch-Dia. Per welder per day. c) S S Piping : 21.0 Man-hour per Meter of 3.0” x Sch. 40, average pipe size. : 6.0 Man-hour per Inch-Meter of 3.0” x Sch. 40, average pipe size. : 7.0 Man-hour per Inch-Dia. of 3.0” x Sch. 40, average pipe size. : 25.0 Inch-Dia. Per welder per day. d) G S Fuel Drum Piping: 9.0 Man-hour per Meter of 3.0” x Sch. 40, average pipe size. e) Steam Tracing : 2.0 Man-hour per Meter of Steam Tracing 0.5” average size. f) HDPE Piping : 1.5 Man hours per Joint (c) Above Ground (A/G) Off-Site Piping: (one joint per 4.0 meter average of pipe length is taken for off-site piping) Total work including cutting, edge preparation, grinding, welding, and inspection, supporting and testing, i.e. fabrication & erection both etc: a) C S Piping : 15.0 Man-hour per Meter of 3.0” x Sch. 40, average pipe size. b) A S Piping : 21.0.0 Man-hour per Meter of 3.0” x Sch. 40, average pipe size. c) S S Piping : 17.0 Man-hour per Meter of pipe of 3.0” x Sch. 40, average size. d) Small Bore Piping : 6.0 Man-hour per Meter of pipe of 3.0” x Sch. 40, average size. e) Steam Tracing : 2.0 Man-hour per Meter of Steam Tracing 0.5”, average size. Note: Please Multiply the Man-hour calculated as above for Estimating the man-hour (MH) required for any other size (D1) by 0.75 X D1/D in case D1 is greater than D, and by 1.5 X D1/D in case D1 is smaller than D. f) Hot Insulation : 5.0 Man-hour Per square meter including jacketing. g) Cold Insulation: 6.0 per square meter of Insulation including jacketing. h) Painting: 6.0 per square meter including Sand Blasting. i) Coating & Wrapping: 0.2 per meter using cold Tape. (d) Tankage: Fabrication & Welding : 250 Ton per month per contractor. Welding of Tankage: 30 Meter Single Run welding per welder per day, (e) Heater: Fabrication & Welding : 125 Ton per month per contractor. We calculate the total Man-hour involvement activity wise based on the above norms of man-hour and accordingly allocate the total Weightage value of the piping work for Planning, Scheduling Monitoring and Review purpose of the project work. Example: In a Refinery Project, followings are the A/G piping work involved in CDU Unit expansion work of the Refinery for which we are Piping Engineer in-charge and we have to find out the Number of welders required for completing the piping work including welding in all respect: A/G CS Piping Diameter x Inch- Mete. InchLength Diameter 4” x 2.6 Km 10400 8667 12” x 250 m 3000 2500 14” x125 m 1750 1458 Total 15150 12650
Man-Hour 39000 MH 8440 4925 52365
Welder’s Day 345 100 58 503
We can see from the table above that 503 welder’s day and 52,365 Man-hours are required to complete the above piping work. Now, based on our schedule of completion, we can plan and deploy welders, manpower, and machineries to complete the above piping work accordingly. Progress Control: Progress control is the comparing of actual progress with scheduled progress and the steps necessary to correct deficiencies or to balance activities to meet overall objectives.
7 Piping Assembly Pipe Assembly involves the various operations like forming, shaping, machining, cutting, welding, cleaning, heat-treatment putting off valves, flanges, and fittings into a finished piping system or into components which may become integral parts of piping systems. Metallic piping and its accessories work are completed by cutting, bevelling, and edge preparation, cleaning, fit-up, flanging and welding of the same. The total line is divided into several spools to facilitate the fabrication and installation of piping work. The piping spools are fabricated either in the workshop or at the work site. Considerable prefabrication is generally done in fabricating plants where specialized equipment is available for the production of piping components under carefully controlled supervision. The fabrication of piping may follow any of the several patterns, including assembly and joining of all pieces at the erection site location. This is because shop assembly, where specialized equipment is available and working conditions are favourable, is conducive to easier, more consistent, and more dependable fabrication than field assembly. The relevant Drawings are studied to prepare the material take off (MTO) list. After the list is prepared, the material Issue Voucher is prepared by the site engineers for indenting the materials required for fabrication of the Spools. After receipt of the materials at site, it is verified and identified for conforming to the specification requirement and correctness of the materials before use. Basis of Piping Assembly: The basis of piping work is the “Approved for Construction” drawings, called as “AFC” drawings and sketches issued by the Consultant to the Contractor. The commonly used drawings are Plans, General Arrangement, Sectional and / or Isometrics, Approved process licensor’s standards and specifications, Consultant’s specifications and documents as below: Process and Instrument Diagram. Piping Material Specification Piping support standards Line list Piping support indices, if supports are not shown in plan. Standard specification of Non-destructive Testing Requirement of Piping Standard specification of Welding Standard specification of Pressure Testing of Erected Piping system Welding specification for fabrication of Piping Piping Materials: In general, we use carbon steel, alloy steel and stainless steel materials for construction of piping work as mentioned below: Carbon Steel : A106 GR B; API 5L GR 5L, GR X52, GR X60 ETC. Low Alloy Steel: A333 GR 3, GR 6 ETC. Alloy Steel : A335 GR P5, GR P9, GR P11, GR 22 ETC. Stainless Steel: A312 GR TP 304, GR 316, GR 321, GR 327, GR 304L, GR 316L, GR 304H, GR 316H, GR 321H
7.1 Applicable Codes and Standards This page lists the cutting, welding, heat treatment and other auxiliary functions for fabrication & erection of piping work shall meet the requirements of the latest editions of the following accepted Standards, Specifications and Drawings of the Project Work: P & ID; General Arrangement Drawings, ISO-Metric Drawing; Spool Drawing; Technical Specifications; and Condition of Contract Documents. ASME B31.3: ASME Code for Pressure piping design, fabrication, erection & inspection. ASME Boiler & pressure Vessel Code, Sec II Part C: Material Specifications for Welding Rods, Electrodes and Filler Metals. ASME Boiler & Pressure Vessel Code, Section V: Non-destructive examination. ASME Boiler & Pressure Vessel Code, Section VIII: Rule for construction of Pressure Vessels. ASME Boiler & Pressure Vessel Code. Section IX: Welding and Brazing Qualifications. I.B.R. (The Indian Boiler Regulations): NACE: Code for Design, Fabrication and Inspection of sour Services material Requirement MR-01-75.
7.2
Piping Fabrication and Assembly
The different stages of piping fabrication and erection involve cutting of pipe, edge preparation, welding and Inspection of pipe. Cutting means dividing the material into two pieces. Bevelling and Edge Preparation means cutting the edge of the work piece in inclined profile (bevelled), i.e., at certain angle as per the groove design and then grinding and filling the same to smooth finish for welding. Edge preparation should be reasonably smooth finish and true to the design of the weld joint groove. Cleaning and Fit-up means removing the slag, oxides, paint, oil, grease, scale or the rust from inside or outside surface of oxygen or arc cut material and truly cleaned to a shining surface. Fit-up is the preparation of the weld joint to the requirement of the design or WPS before welding of the same. The weld metals should be tacked together either directly or with the help of plate cleat of the same material of the pipe or with couplers, yokes or clamps after alignment and matching with each other within the dimensional limits. A wire spacer of the suitable diameter is used to maintained the required root gap in case of butt-weld joint. The qualified welder should do tack welding because the tack weld becomes a part of the final weld. Tack welds are equally spaced approximately at 75 mm to 150 mm depending on small to big diameter pipe. Defective tack weld should be removed prior to the actual welding by grinding or other means.
7.2.1 Pipe Cutting Pipe Cutting is the methods used to cut materials into different shapes and sizes. They can perform simple cutting jobs, complex shaping processes, and nesting procedures that minimize material waste. Cutting services can process standard or nonstandard materials such as metals, plastics, thermoplastics, rubber, glass, stone, marble, granite, composites, and foams. Cutting services may perform flame cutting, laser cutting, and plasma cutting operations. Flame cutting uses an oxygen or gas flame to heat metals in preparation for cutting. There are a number of different cutting methods and services available. The suitability of each process to the service depends on the material being cut, the desired tolerance, the volume of material, and the cost. Cutting of Different Metals are done with the method ass mentioned below: (a) Carbon Steel and Low-Carbon Steel: Gas-Cutting, Metal Arc-Cutting Hacksaw Cutting, Grinding or Machine-Cutting cuts Carbon steel and low carbon steel (Chromium up to 2.5%) pipe, plate or any other components. After Gas-Cutting or Metal Arc- Cutting, the oxides or slag are removed by chipping with chisel & hammer or by grinding. (b) High-Alloy Steel, Stainless Steel and other Non-Ferrous Metals: Certain metals cannot be cut by gas-cutting method successfully because the chromium and nickel oxides produce by the heat of the flame melt at higher temperature than the parent metal. Similarly, High alloy steel, cupronickel, nickel alloys, aluminium, copper and copper alloys and other non ferrous metals, and Cast Iron can only be cut by the Machine Cutting, Plasma-Cutting, Oxy-Arc Cutting, Oxy-Lancing Cutting, Powder Process Cutting, Powder Lancing Cutting, Grinding or Hack Saw Cutting. Oxygen cutting is entirely unsuitable for such metals. (c) Cast Iron: The cutting of Cast Iron is difficult due to the nature of its constituents, which include
silicon and graphite. Neither of these is easily oxidized. For cutting cast iron, a special blowpipe having larger passages is required to pass greater quantities of both oxygen and acetylene. The quantity of cut and accuracy obtained on the surface is extremely poor. An excess of acetylene is required in the heating flame for conversion of the silicon and graphite constituents into a slag. This generated slag is more or less removed by the pressure of then gas behind the flame or by mechanical manipulation of an iron rod during the actual cutting operation. The blowpipe should be hold 10 mm above the surface of cast iron while cutting. a) Saw-Based Cutting: Many cutting services perform band-saw cutting operations and other sawbased processes. Band-saw cutting services use a power saw with an endless, toothed steel belt or band that is driven continuously around the circumference of two pulleys. Other types of saw-based cutting services are circular cold-saw and mitre cutting. Circular cold-saw cutting services use a toothed, circular blade which rotates at a high speed. If an angled cut is desired, mitre cutting is used. b) EDM Cutting: Cutting services that perform electrical discharge machining (EDM) operations use specialized equipment. EDM cutting services specialize in cutting conductive materials with a thin electrode. This electrode is a thin wire (usually .004"- .012") that follows a programmed path without physically touching the part. With EDM cutting, the part is charged to a certain level and surrounded by de-ionized water. This generates a spark which jumps the gap and melts a small amount of material on the part. c) Flame, Laser, and Plasma Cutting: Cutting services may perform flame cutting, laser cutting, and plasma cutting operations. Flame cutting equipment uses an oxygen or gas flame to heat metals in preparation for cutting. Laser cutting services use a CNC-controlled, non-contact tool to make quick and precise cuts with a narrow cutting groove. Laser cutting is an adaptable operation that can be set up quickly and can cut through different types of materials. Plasma cutting services perform plasmaarc cutting, an operation which involves melting an area with an arc and then cutting it with a highvelocity, high-temperature, ionized gas. There are two main types of laser cutting: (i) CO2 and (ii) Nd- YAG. Both types of laser cutting services offer advantages such as high accuracy, cutting of unlimited shapes, clean cutting that requires minimum finishing, minimal generation of heat, and distortion-free cutting. Water jet-Based Cutting use water and water abrasive jets for cutting the materials. Cutting services that use water and water abrasive jets use heavily-pressurized water (20,000 - 60,000 psi) flowing through a nozzle ("jewel") that is approximately 0.010" in diameter. Benefits include minimal heating during cutting, low side-loads, and the ability to accomplish complex shapes and tight inside radii. Water jet cutting is well-suited for prototypes and short runs because of their fast setup and programming times. Water and water abrasive jets are used mostly for two-dimensional cutting (2D cutting). Routing cutting services use a vertical, high-speed, revolving spindle and cutter which mills out the surfaces or edges of materials. Tube or pipe cutting services specialize in cutting tubing, pipe, or bar stock to a desired length or mitre angle in a variety of shapes (square, rectangle, and round). d) Oxy-Flame Cutting: The oxygen has great affinity for ferrous metals. The cutting of the ferrous metal involves the closely regulated jet or stream of pure oxygen on to the area heated previously to the ignition temperature (about 870 0C, or when the metal reaches the bright red colour). Moving the
oxygen jet at a uniform speed oxidizes the metal and a narrow Iron Oxide is removed from the metal with the pressure of oxygen or it is cut. The accurate result is obtained if close control is exercised. The cutting blow pipe consist of (1) a central nozzle supplying the cutting jet of oxygen at a constant pressure and speed, (2) an annulus through which the fuel gas passes for heating the metal. Both, the oxygen and the fuel gas are fed from separate cylinders having separate gas regulator valves. The fuel gases most commonly used are acetylene, propane or hydrogen. The heating flame has two purposes, (1) to provide sufficient heat to raise a small area of the steel surface to the “ignition” temperature, and (2) transmit sufficient heat to the top surface of the steel to offset the thermal conductivity of the metal. The intensity of heat must also be sufficient to break up surface scale and maintain the steel at ignition temperature regardless of any surface irregularities. The removal of surface scale is of particular importance when cutting alloy steels, such as armour plate. The flame cutting causes a slight increase in the surface hardness of the cut edges, the actual depth depending on the carbon content and alloying element present in the steel, and on the mass of the metal. The hardening effect on low-carbon steels, i.e., mild steel, however is negligible for thickness up to 25 cm. For greater thickness it is advisable to preheat the metal prior to cutting to avoid any chilling effect. Procedure: First the heating flame is adjusted and set to a natural blue flame with the white cone at the centre by adjusting fuel gas and oxygen with the help of regulator valves. Then, the cutting torch is kept on the metal surface with the white cone 6 mm above the work surface. Heating is started with the burning of fuel gas. When the metal reaches a bright red colour, the oxygen supply is switched on by pressing the handle of the oxygen valve. White cone of the flame is kept just clear of the work surface and a penetrating hole is ensured before commencing to move the cutting torch. Whenever possible, the operator should move the cutting torch towards him for good quality of cutting. The cutting of the cast iron is felt very difficult due to the nature of its constituents, which include silicon and graphite, neither of which is easily oxidized. Much oxygen cutting is done with the machines, particularly if the cut is long. Machine gas cutting has many advantages over hand gas cutting and result in greater accuracy and better edge finish. A wide variety of types of machines are available, e.g., Stationary general-purpose or universal models, multi-burner machines, flame-planning machines, straight-line and circle cutting types, hole cutting machines, bar and joist cutting machines, tube-cutting machines etc. There is some pantograph or electronic devices enabling profiles to be accurately copied from templates or direct from drawings. Table: Data for cutting Carbon Steel by Oxy-Acetylene Process by hand Plate Nozzle Thickness. Size (mm) (mm)
Oxygen Pressure (lb./cm 2)
Oxygen Acetylene Consumption Consumption (cu. Ft/hr) (cu. Ft/hr)
6 12 19 25
25-30 30-35 35-40 35-50
50-100 100-165 100-135 165-215
1.2 1.2 1.2 1.6
15-17 17-19 19-21 20-25
37.5 50
1.6 1.6
40-60 45-65
180-250 200-265
20-30 23-33
Table: Data of Calorific Value of Fuel Gases and Flame Temperature Fuel
Calorific Value B.Th.U. 1500 2400 289 460-550 1,075
Acetylene Propane Hydrogen Coal gas Methane
Flame Temperature 0 C 2,632 2,500 2,210 2,154 2,066
e) Oxy-Arc Cutting: The oxy-arc cutting is done by the fine-point concentration of heat generated by an electric arc and a stream of oxygen. In fact, it is a combination of a flame cutting and a metal arc cutting. Because the heat is concentrated in such a small area, the process is very useful piercing holes in the plate up to thickness exceeding 15 cm. The arc is established between the end of a hollow coated electrode and the metal to be cut. The oxygen flows through the core of the electrode. The electrode is consumed during cutting. Due to the high temperature of the arc, (1) cutting start immediately without preheat (2) oxidation resistance material can be cut and pierced, (3) steel can be cut and pierced at high speed, and (4) heavily rusted and corroded parts are cut easily. The equipment consists of a special electrode holder or gun, special hollow electrodes, an oxygen cylinder and regulators, an AC or DC welding set and a helmet etc. This process is not intended for general cutting purpose, i.e. to replace normal cutting process. It is used where the normal process cannot be used. The cut is not as clean or smooth as that produced with oxy-acetylene process. Table: Data for “Oxy-Arc” Electrode Cutting Plate Material Thickness Type
6 mm 12.5 mm
25 mm
SS CS CI SS CS CI SS CS CI
Oxygen Pressure Lb./in 2 3-5 75 10 5-10 75 10-15 15-20 75 20-25
Current (Amps) 175 175 180 185 175 185 200 175 200
f) Oxygen-Lance Cutting: This process of cutting is, to some extent, similar to the Oxy-Arc Cutting process except the use of the oxygen lance in place of hollow electrode.
g) Powder Cutting: Above, it is mentioned that metals like Stainless steel, Nickel Alloys, Copper Alloys, High Alloys steels and Cast Iron can only be successfully cut by the Powder- Cutting process, sometimes termed as “flux-injection process”. In this process, a finely divided iron-rich powder is conducted separately to the reaction zone of the cutting equipment by the compressed air or nitrogen. The combustion of the iron powder increases the temperature of the reaction, thereby increasing the fluidity of the refractory oxides. These refractory oxides are removed by the combined melting and fluxing action and, also to the certain extent, by the eroding action of the iron particles. A clean surface is thus exposed to the oxygen stream and the cut progresses through the thickness of the metal. The quality of the cut is slightly inferior to that obtained by the gas cutting process. A powder-dispensing unit is required by which the quantity of powder flowing into the reaction zone in a given period of time can be varied. The machine mainly consists of powder storage bowl, powder blowpipe, powder valve, powder nozzle and connecting tubing. Iron powder is carried down outside the cutting nozzle and is injected through the heating flame into the cutting oxygen at a point approximately 2.5 cm below the surface of the nozzle. The clearance between the nozzle and the work piece is maintained 2.5 cm to 3.5 cm to permit the powder to mix and burn with the oxygen in the cutting stream. The intense heat created by the combustion of powder makes it unnecessary to preheat stainless steels. The remainder of the equipment is similar to the normal oxygen cutting equipment. The dispenser is supplied from a source of clean dry air capable of delivering a flow rate of 50 cu. Ft./hr at a line pressure of 50 lb./sq. in.. Oxygen must not be used in any circumstances in place of air for operating the dispenser. Nitrogen may be used in place of air as an alternative. Table: The approximate air consumption Pressure (lb/sq. in.) 2 5 6 10
Consumption (Cu. Ft/hr) 25 30 35 40
h) Powder Lance Cutting: Powder Lancing is the technique, which provides a means of cutting very thick pieces of metal, which are difficult or impossible to cut by any other means. The use of a special “Thermit “powder mixture enables an exceedingly high temperature to be reached and a thickness up to several feet can be cut with ease. The apparatus consists of a tubular lance, a special holder incorporating an injector and dual valve arrangement, these being coupled to a high-pressure oxygen supply and a standard powder dispenser. The depression of the control lever causes the main oxygen stream to draw a variable flow of powder from the dispenser, conveying it through the lance pipe to the action zone. During the operation, the pipe is consumed at low rate. The dispenser is charged with a mixture of iron and aluminium powder in the proportion of 9 lb. of iron to 1 lb. of aluminium. Heating the lance tip to red heat and opening the control lever starts the reaction, whereupon the pipe may be directed at the start of the cut without heating the spot on the material in order to affect a start. The lance must be allowed to burn with a gap of 50 cm between its tip and the face of the work. To effect the maximum economy, bronze and copper will require some degree of preheat and require lower oxygen pressure than other material.
i) Metal Arc Cutting: The metal-arc cutting is the process of cutting the metal with the help of an ordinary metal-arc electrode. This method is only be used if none of the other process of cutting is available. It is only used for emergencies because the width of cut is about twice the diameter of the electrode and the electrode melts away very rapidly. Table: Data for cast iron cutting with Oxy-Acetylene Process Metal Nozzle Oxygen Oxygen Thickness Size Pressure Consumption (mm) (mm) (Lb/sq.in.) (cu.ft / ft. run)
Acetylene Consumption (cu.ft / ft. run)
6-37 37-75 75-125
10 15 20
1.2 1.6 2.4
110 120 130
25 50 140
Table: Depth of Hardness produced by various cutting processes Cutting process
Shearing Oxy-Propane Oxy-Coal Gas Oxy-Acetylene Cold Sawing Milling
Depth of Depth of Hardness Hardness in Mild In Low-Alloy steel Steel (mm) (mm) 11.25 6.50 6.00 3.50 4.00 3.75 4.75 2.00 1.75 1.00 1.00 1.25
With the plate horizontal and electrode at about 45 0, hold a fairly long arc and move the tip of the electrode up and down at the edge of the plate. As the metal melts, brush it downward with the help of arc. Feed the electrode into the slot that is formed and continue working the tip of the electrode up and down to melt the plate and assist the molten metal to run away underneath. It is essential to allow the metal to flow freely out of the cut. Table: Data for Bevel-Cutting (Up to 45 0) . Plate Nozzle Thickness Size (mm)
Acetylene Oxygen Pressure Pressure (lb/sq. in) (lb/sq. in)
Speed (ft/hr)
6mm 12mm
2 2
66 42
0.8 1.5
30 50
19mm 25mm 50mm
1.5 1.5 1.5
2 60 39 2 60 34 2 70 30 Table: Data for Gauging with Oxy-Acetylene Flame
Dimension of Groove W x D (mm) 7.5x6 12x10.5 19x19
Oxygen Gauging Acetylene Oxygen Pressure Speed Consumption Consumption (lb/sq.in) (cm/min) (cu.ft/hr) (cu.ft/min)
55-60 90-100 75
30-54 66-84 3-5
40-43 67-73 51-57
93-100 291-317 636-713
Table: Performance data for Oxy-Acetylene Cutting Plate Heating Thickness Oxygen mm Pressure Lb/in 2
Heating Oxygen Consumption Cu.ft/hr
Cutting Oxygen Pressure Lb/in 2
Cutting Acetylene Cutting Oxygen Consumption Speed Consumption Cu.ft/hr Ft/hr Cu.ft/hr
6 12 25 31 37 50 62 75
15 19 19 19 21 21 21 23
25 30 37 40 42 47 50 52
21 61 144 152 156 170 178 277
15 20 20 20 25 25 25 30
16 20 20 20 23 21 21 25
76 65 50 45 42 37 32 30
j) Under-Water Cutting: It seems that the underwater cutting of metal is difficult operation. In fact, it is no more difficult than the surface cutting. Normally, all cutting process can be used for under water cutting as mentioned below:. (i) Oxy-Acetylene Cutting: The oxy-acetylene process is suitable for water cutting at depth up to 8 meter. The cutting equipment is similar to that for surface cutting except that a supply of compressed air is required to shield the pre-heat area and to supply the oxygen. The oxy-acetylene process has the advantage of ease of regulation of gases. The luminous inner cone is easily visible and in water it has a distinctive blue-green colour. Unfortunately, at the depth of 8 meter, the back pressure due to the pressure of sea water is 11.1 lb/sq. in., leaving the oxy-acetylene gas pressure only 3.9 lb/sq. in. for cutting purposes, which is suitable only for medium-size tips. (ii) Oxy-Hydrogen Cutting: The oxy-hydrogen cutting process is suitable under water cutting for
depth in excess of 8 meter because hydrogen can be compressed beyond the 15 lb/ sq. in. limit of Acetylene. Because of the lower temperature of the oxy-hydrogen flame (4400 0 F), the hydrogen gas is not usually employed at depth less than 8 meters. The gas pressure at the depth above 8 meter is also reduced to but to the extent of oxy-acetylene cutting process. For this reason, the use of gas torches is confined to the cutting of steel. (iii) Oxygen-Arc Cutting: The oxygen-arc cutting is particularly most useful for cutting under water, especially at depth greater than 8 meter. The heat generated is nearly half as much as that of the oxyhydrogen torch. Also it is much safer to use, especially in the presence of oil. Using an 8 mm diameter hollow electrode, 300 amps at 30-40 volts, and oxygen pressure of 40-80 lb/sq. in., 6 mm plate can be cut at a speed of 27 in/min at a depth of 30 ft. With the same torch, 37 mm thick plate can be cut at a speed of 15 cm/min. (iv) Metal Arc Cutting: Under water cutting with the help of Metal arc cutting is also possible, but should only be employed if other process is not available. It is much slower and more difficult to perform. A 5 mm 300 amp, 40-55 volts, is used for Metal arc cutting. A D.C. straight-shielded electrode (water proofed by dipping in a suitable solution) used at polarity is advisable in order to avoid the bubbles due to electrolysis. 6 mm plate can be cut at a speed of 33 cm/min. Table: Pressure for Oxy-Acetylene Under-Water Cutting Depth of water Oxygen Pressure (meter) (lb/sq. in) 3 75 6 100 9 125
Acetylene Pressure (lb/sq. in) 5 7.5 12
Table: Pressure for Oxy-Hydrogen Under-Water Cutting Depth Air (meter) Pressure (lb/sq.in)
Plate Thickness (mm)
Oxygen / Hydrogen Pressure (lb/sq. in)
.3.3 6.6 9.9 13.2 16.5 19.8 23.1 26.4 27.7 31
19 19 19 19 19 19 19 19 19 19
42 45 48 51 56 61 67 74 82 91
14 19 23 27 31 36 40 45 49 53
7.2.2
Piping Fabrication
Shop fabrication / prefabrication: The purpose of shop fabrication or pre-fabrication is to minimize work during erection to the extent possible. Piping spool, after fabrication, shall be stacked with proper identification marks written with paint, so as to facilitate their withdrawal and sorting at any time during erection. The flange faces and threads shall be adequately protected with removable rust preventive coating or grease during storage period. We shall take care to avoid any physical damage to flange faces and threads during storage period. All prefabricated piping spools should be painted with one coat of primer paint after through surface cleaning before stacking to protect the pipe from rust during storage. Piping Material: Pipe, pipe fittings, flanges, valves gaskets, studs bolts etc. used in a given piping system should be strictly as per the “Piping Material Specification” or as per the drawings for the “Pipe Class” specified for that system. Dimensional Tolerances: Dimensional tolerances for piping fabrication should be as per Standard and specifications. An extra pipe length of 100 mm over and above the dimensions indicated in the ISO drawing may be left on one side of the pipe at each of the field welds. During erection, the pipe with extra length at each field weld should be cut to obtain the actual dimension occurring at site, Isometrics, if supplied may have the field welds marked on them. Pipe Joints: In general, joining of lines 2” and above in process and utility piping should be accomplished by butt-welds and minimum numbers of flange joints strictly for maintenance of the piping. Joining of lines 1-1/2” and below should be by socket welding or butt welding or threaded joints as specified in “Piping material Specifications”. However, in piping 1-1/2” and below where socket welding or threaded joints are specified in the specification, butt-welds may be used with the approval of Client or Engineer-in-Charge for pipe-to-pipe joining in long runs of piping. Flange joints should be used at connections to Vessels, equipment’s Valves and where required for ease of erection and maintenance as indicated in drawings. Butt Weld / Socket Weld: End preparation, alignment and fit-up of pipe pieces to be welded, should be done strictly as per specification. The welding, preheating, post-heating and heat treatment should be done as described in the welding specification and NDT specification. Screw Joint: In general, Galvanized piping shall have threads as per IS: 554 or ANSI B2.1 NPT as required to match threads on fittings, valves etc. All other piping shall have threads as per ANSI B2.1 tapered unless specifies otherwise. The male threads should be coated with thread sealant and the joint tightened sufficiently for the threads to seize and give a leak proof joints. Some time the threaded joints are to be seal welded as per specification requirement. Flange Joints: The flange joints are made with the help of companion flanges welded to the pipe. Then, a suitable Gasket is put in between two flange’s faces. The flanges are tightened with suitable bolts and nuts. The length of the pipe, proper size of the plate etc. is cut as per the drawing requirement to complete
piping and its support work. The cutting is done with one of the following methods: All flange facings should be true and perpendicular to the axis of pipe to which they are attached. Flange boltholes should straddle to the normal centrelines unless different orientation is shown in the drawing. Wherever a spectacle blind is to be provided, drilling and tapping for the jackscrews in the flange should be done before welding it to the pipe. Bending & forming: Bending is the turning of one end of the pipe at a certain angle (Generally 45 0 or 90 0) with respect to the other end of the pipe on a plain surface, either in hot or cold condition. Bending should be as per ASME B31.3 except that corrugated or creased bends should not be used. Cold bends for lines 1-1/2” and below, with a bend radius of 5 times the nominal diameter should be used as required in place of elbow wherever allowed by piping specifications. Bending of pipes 2” and above may be required in some cases like that for headers around heaters, reactors etc. Inspection of each bend should be carried out and the completed bend should have a smooth surface, free from cracks, buckles, wrinkles, bulges, flat spots and other serious defects. They shall be true to dimensions. The flattening of a bend, as measured by the difference between the maximum and minimum diameter at any cross-section, shall not exceed 8 % and 3 % of the nominal outside diameter, for internal and external pressure respectively. Branch Connections: Branch connections shall be as indicated in the piping material specifications. The end preparation, alignment, spacing, fit-up and welding of branch connections should be done as per welding specifications. Reinforcement pads should be provided wherever indicated in drawings or specifications etc. Mitre Bends and Fabricated Reducers: The specific application of welded Mitre bends and fabricated reducers should govern by the piping material specifications. Generally, all 90 deg. Mitres should be piece 3-weld type and 45 deg. Mitres should 3-piece 2-weld type and reducers per standard unless otherwise specified. The radiographic shall be done as Material specifications for process and utility systems and NDT specifications for steam piping under IBR, radiographic requirements of IBR shall be complied with. Cutting and Trimming of Standard Fittings & Pipes: Components like pipes, elbows, couplings, half-couplings etc. should be cut or trimmed or edge prepared wherever required to meet fabrication and erection requirements, as per drawings and welding groove detail. Nipples as required should be prepared from straight length of pipe. Galvanized Piping: Galvanized carbon steel piping should be completely cold worked so as not to damage galvanized surfaces. This piping involves only threaded joints and additional external threading on pipes may be required to be done as per requirement. Welding should not be done after galvanizing of the fabricated pipe. Jacketed Piping: Pre-assembly of jacketed piping to the maximum extent possible should be accomplished at shop. Position of jump over and nozzles on the jacket pipes, fitting etc. should be marked according to pipe disposition and those shall be prefabricated to avoid damaging of inner pipe and obstruction of jacket space. However, valves flow glasses, in line instruments or even
fittings shall be supplied as jacketed. Miscellaneous: We shall fabricate miscellaneous elements like flash pot, seal pot, sample cooler, supporting elements like turn buckles, extension of spindles and interlocking arrangement of valves, operating platforms as required by the drawing in the fabrication shop. 5.3.5 PIPING ERECTION During assembly of the piping, mainly, the following jobs are supposed to be performed to complete the piping system, but not limited to the followings. Grinding of edges of pipes, fittings, flanges etc. to match mating edges of uneven/different thickness wherever required and for making the weld groove before welding, modifications like providing additional cleats, extension of stem of valve, locking arrangement of valves etc, preparation of Isometrics, bill of materials, supporting details of all Small Bore piping size up to 2” within the piping battery limit, spun concrete lining of the inside of pipes 3” NB & above including fittings and flanges as required in accordance with specification, rubber lining inside pipes, fittings, flanges as and when required, in accordance with specification, radiography, stress relieving, dye penetration, magnetic particle test etc, casting of concrete pedestals and fabrications & erection of small structures for pipe supports including supply of necessary materials, providing insert plates in concrete structures and repair of platform gratings around pipe openings, flushing and testing of all piping systems as per standards specification for inspection, flushing and testing of piping systems, Pickling , if applicable, as per standard specification for chemical cleaning of C S such as suction piping of compressors, Lube oil piping etc. Cleaning of piping before erection: Before erection of piping, all pre-fabricated spool pieces, pipes, fittings etc. shall be cleaned inside and outside by suitable means. The cleaning process should include removal of all foreign matter such as scale, sand; weld spatter chips etc. by wire brushes, cleaning tools etc. and blowing with compressed air or flushing out with water. Special cleaning requirements for some services such as pickling etc., if any, shall be done as specified in the piping material specification or isometric drawings or line list. S.S jacketed piping requiring pickling shall be pickled to remove oxidation and discolouring due to welding before erection. Cold Pull: Wherever cold pull is specified, the same shall be maintained by providing the necessary gap, as indicated in the drawing. This pull should be checked by the piping engineer and should be confirmed in writing, certifying that the gap between the pipes is as indicated in the drawing before drawing the cold pull. Stress relieving shall be performed before removing the gadgets for cold pulling. Slopes: Slopes as specified for various lines in the drawings or P & ID shall be maintained during erection of piping. Expansion joints / Bellows: Great care shall be taken while aligning for handling and installation of expansion joints. An Expansion Joints shall never be sling from bellows corrugations or external shrouds, tie or rods or angles etc. An Expansion Joints/Bellows shall preferably be sling from the end pipes or flanges or on the middle pipe. All expansion joints shall be delivered to the contractor at “Installation length”, maintained by means of shipping rods, angles welded to the flanges or weld ends or by wooden or metallic stops. Expansion Joint’s stop blocks shall be carefully removed after hydrostatic testing of the piping system. Angles welded to the flanges or weld ends shall be trimmed by saw or as per manufacturer’s instructions and the flanges or weld ends shall be ground smooth.
The expansion joint should be placed in between the mating pipe ends or flanges and should be tack welded or bolted and the mating pipes should be checked for correct alignment. Butt-welding should be carried out at each end of the expansion joint for welding type expansion joint and the mating flanges shall be bolted for the flanged Expansion Joint. After the Expansion joint is installed, it should be ensured that the mating pipes and Expansion Joints are in correct alignment and that the pipes are well supported and guided. The expansion Joint shall not have any lateral deflection. The Contractor shall maintain parallelism and Joints should be correctly aligned and that the pipes are well supported and guided. Precautions: The following precautions should be taken during installation of Expansion Joints, Earthen lead shall not be attached with the expansion joint for carrying out welding. The expansion bellow shall be protected from all weld spot and welding spatters. Hydrostatic testing of the system having expansion joint shall be performed with shipping lugs in position. These lugs shall be removed only after testing and certification of the piping system is over. Flange connections: While fitting up mating flanges, care shall be taken to properly align the pipes and to check the flanges for trueness, so that faces of the flanges can be pulled together, without inducing any stresses in the pipes and the equipment nozzles. Extra care shall be taken for flange connections to pumps, turbines, compressors, cold boxes, air coolers etc. The flange connections to equipments shall be checked for misalignment and excessive gap etc. after the final alignment of the equipment is over. Temporary protective covers shall be retained on all flange connections of pumps, turbines, compressors and other similar equipments, until the piping these equipments are completed satisfactorily. The assembly of a flange joint shall be done in such a way that the gasket between these flange faces is uniformly compressed. Bolt shall be tightened in a proper sequence to achieve the flange connections. All bolts shall extend completely, three threads minimum, through their nuts but not more that ¼”. Steel to C.I flange joints shall be made up with extreme care, tightening the bolts uniformly after bringing flange flush with gaskets with accurate pattern and lateral alignment. Vents and Drains: All high points and low points in piping system shall be provided with vent and drain respectfully, even if these are not shown in the drawings. The details of vents and drains shall be as per piping material specifications or job standards. Valves: Valves shall be installed with spindle or actuator orientation or position as shown in the layout drawings. In case of any difficulty in doing this or if the spindle orientation or position is not shown in the drawings, Vales should be installed as per the flow direction marked on the body of the valve. Care shall be exercised to ensure that globe valves, check valves, and other uni-directional valves are installed with the “Flow direction arrow” on the valve body pointing in the correct direction Of flow of the fluid in piping. If the direction of the arrow is not marked on such valves, this shall be done in the presence of Engineer-in-Charge. Instruments: Installation of in-line instruments such as Restriction Orifices, Control Valves, Safety Valves, Relief Valves, Rota meter, Orifice Flange assembly, Venturimeter, Flow Meter etc.
shall form a part of piping erection work and should be done very carefully. The limits of piping and instrumentation work will be shown in drawings or standards or specifications. Orientations or locations of take-offs for temperature, pressure, flow; level connections etc. shown in drawings shall be maintained and done carefully. Flushing and testing of piping systems that include instruments mentioned above and the precautions to be taken are, generally, covered in flushing, testing and inspection of piping. Care and adequate precautions shall be taken to avoid damage and entry foreign matter into instruments during transportation, installation, testing of piping system. Bolts and Nuts: Molly-coat grease mixed with graphite power shall be applied unless otherwise specified in piping class on all bolts and nuts during storage, after erection and wherever flange connections are broken and made-up for any purpose whatsoever. The contractor within the rates for piping work shall supply the grease and graphite powder. Pipe Supports: Pipe supports are designed and located to effectively sustain the weight and thermal effects of the piping system and to prevent and to prevent its vibrations. Locations and design of pipe supports will be shown in drawings for lines 2” NB & above. For line below 2” NB Contractor shall locate and design pipe supports in line and obtain approval of Engineer-in-Charge on drawings prepared by Contractor, before erection. No pipe shoe or cradle shall be offset unless specifically shown in the drawings. Hanger rods shall be installed inclined in a direction opposite to the direction in which the pipes move during expansion. Preset pints of all spring supports shall be removed only after hydrostatic testing and insulation is over. Springs shall be checked for the range of movement and adjusted if necessary to obtain the correct positioning in cold condition. These shall be subsequently adjusted to hot setting in operating condition. The following points shall be checked after installation, with the Engineer-in-Charge and necessary confirmation in writing obtained certifying that: All restraints have been installed correctly. Clearances have been maintained as per support drawings. Insulation does not restrict thermal expansion All temporary tack welds provided during erection have been fully removed. All welded supports have been fully welded.
8 Pipe Welding Pipe Welding: Welding joins two metal parts into a single mass or whole. This is often done by melting the work pieces and adding a filler material to form a pool of molten material (weld pool) that cools to become a strong weld joint. Welding is a potentially hazardous undertaking and precautions are required to avoid burns, electric shock, vision damage, inhalation of poisonous gases and fumes, and exposure to intense ultraviolet radiation. Several welding procedures/techniques are developed like Shielded Metal Arc Welding (SMAW), now one of the most popular welding methods. Robot welding is commonplace in industrial settings, and researchers continue to develop new welding methods and gain greater understanding of weld quality and properties. Many different energy sources can be used for welding, including a gas flame, an electric arc, a laser, an electron beam, friction, and ultrasound. While often an industrial process, welding may be performed in many different environments, including open air, under water and in outer space.
8.0
Applicable Codes of Welding:
1. American Welding Society (AWS) Codes: American Welding Society Standards provide information on the welding fundamentals; weld design, welder's training qualifications, testing and inspection of the welds and guidance on the application and use of welds. Standard Title Number Standard symbols for welding, brazing, and AWS A2.4 non-destructive examination AWS A3.0 Standard welding terms and definitions Specification for carbon steel electrodes for AWS A5.1 shielded metal arc welding AWS A5.2 Specification for Iron and Steel welding rods Specification for Low Alloy Steel covered arcAWS A5.5 welding electrodes Specification for mild steel covered arcAWS A5.6 welding electrodes Carbon Steel Electrodes and Fluxes for AWS A5.17 Submerged Arc Welding Specification for carbon steel electrodes and AWS A5.18 rots for gas shielded arc welding Carbon Steel Electrodes for Flux Cored Arc AWS A5.20 Welding Low Alloy Steel Filler Metals for Gas AWS A5.28 Shielded Arc Welding Low Alloy Steel Electrodes for Flux Cored AWS A5.29 Arc Welding Guide for the non-destructive examination of AWS B1.10 welds AWS D1.1 Structural welding (steel) AWS D1.2 Structural welding (aluminium) AWS D1.3 Structural welding (sheet steel) AWS D1.4 Structural welding (reinforcing steel) AWS D1.5 Bridge welding AWS D1.6 Structural welding (stainless steel) AWS D1.7 Structural welding (strengthening and repair) AWS D1.8 Structural welding seismic supplement AWS D1.9 Structural welding (titanium) AWS D8.1 Automotive spot welding Automotive spot welding electrodes AWS D8.6 supplement
AWS D8.7
Automotive spot welding recommendations supplement AWS D8.8 Automotive arc welding (steel) AWS D8.9 Automotive spot weld testing AWS D8.14 Automotive arc welding (aluminium) AWS D9.1 Sheet metal welding AWS D10.10 Heating practices for pipe and tube AWS D10.11 Root pass welding for pipe AWS D10.12 Pipe welding (mild steel) AWS D10.13 Tube brazing (copper) AWS D10.18 Pipe welding (stainless steel) AWS D11.2 Welding (cast iron) AWS D14.1 Industrial mill crane welding AWS D14.3 Earthmoving & agricultural equipment welding AWS D14.4 Machinery joint welding AWS D14.5 Press welding AWS D14.6 Industrial mill roll surfacing AWS D15.1 Railroad welding AWS D15.2 Railroad welding practice supplement AWS D16.1 Robotic arc welding safety AWS D16.2 Robotic arc welding system installation AWS D16.3 Robotic arc welding risk assessment AWS D16.4 Robotic arc welder operator qualification AWS D17.1 Aerospace fusion welding AWS D17.2 Aerospace resistance welding AWS D18.1 Hygienic tube welding (stainless steel) AWS D18.2 Stainless steel tube discoloration guide AWS D18.3 Hygienic equipment welding 2. American Petroleum Institute (API) Standards: The American Petroleum Institute (API) maintains over 500 standards covering the oil and gas field. The following is a partial list specific to welding: Code Title Welding Inspection and API RP 577 Metallurgy Welding of pipelines and API 1104 related facilities 3. International Organization for Standardization (ISO) Standards: International Organization for Standardization (ISO) has developed over 18500 standards and over 1100 new standards are published every year. The following is a partial list of the standards specific to welding: Standard Title Number
ISO 2560
ISO 3580
ISO 3581
ISO 3834 ISO 4063 ISO 5817
ISO 6520-1
ISO 6520-2
ISO 6947 ISO 9606 ISO 9692-1
ISO 9692-2 ISO 9692-3
ISO 13847 ISO 13916
ISO 13918
Welding consumables. Covered electrodes for manual metal arc welding of non-alloy and fine grain steels. Classification Covered electrodes for manual arc welding of creep-resisting steels - Code of symbols for identification Covered electrodes for manual arc welding of stainless and other similar high alloy steels Code of symbols for identification Quality requirements for fusion welding of metallic materials, five parts. Welding and allied processes - Nomenclature of processes and reference numbers Welding. Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding excluded). Quality levels for imperfections Welding and allied processes — Classification of geometric imperfections in metallic materials — Part 1: Fusion welding Welding and allied processes — Classification of geometric imperfections in metallic materials — Part 2: Welding with pressure Welds. Working positions. Definitions of angles of slope and rotation Qualification test of welders — Fusion welding, parts 1 to 5 Welding and allied processes. Recommendations for joint preparation. Manual metal-arc welding, gas-shielded metalarc welding, gas welding, TIG welding and beam welding of steels Welding and allied processes. Joint preparation. Submerged arc welding of steels Welding and allied processes. Joint preparation. Part 3: TIG and MIG welding of aluminium and its alloys Petroleum and natural gas industries - Pipeline transportation systems - Welding of pipelines Welding - Guidance on the measurement of preheating temperature, inter-pass temperature and preheat maintenance temperature Welding - Studs and ceramic ferrules for arc stud welding
ISO 13919-1
Welding - Electron and laser-beam welded joints - Guidance on quality level for imperfections - Part 1: Steel ISO 13919-2 Welding - Electron and laser-beam welded joints - Guidance on quality level for imperfections - Part 2: Aluminium and its weld able alloys ISO 13920 Welding - General tolerances for welded constructions - Dimensions for lengths and angles - Shape and position ISO 14112 Gas welding equipment - Small kits for gas brazing and welding ISO 14175 Welding consumables — Gases and gas mixtures for fusion welding and allied processes. ISO 14341 Welding consumables. Wire electrodes and deposits for gas shielded metal arc welding of non alloy and fine grain steels. Classification ISO 14554 Resistance welding ISO 14744 Electron beam welding, six parts 4. Bureau of Indian Standards: IS 823 is the Indian Code for Welding of Mild Steel (For structural steel). Welding Procedures: There are various types of welding procedures based on utilization of different kind of energy, e.g., electrical energy, oxy-acetylene gas, friction force, explosion, Thermit energy, Ultrasonic, and electron beam. Based on the type of union of two parts of metal, welding is mainly divided into two groups: (i) Fusion Welding and (2) Pressure Welding. Fusion Welding: In fusion welding, the weld metals are melted by production of tremendous heat to melt the metal with or without filler metals and allowed to intermingle together to form a homogeneous weld joint when cooled without application of any pressure. The heat is produced by different methods as mentioned, such as, Electric Arc; Gas Flame; Electric Resistance; Thermit and Electron Beam. Pressure Welding: In pressure welding, the weld metals, either after heating but without melting or in cold condition, are brought together and a tremendous pressure is applied to force the surfaces to form a union into intimate contact. Welding Group (a) Fusion Welding
Type of Welding Procedures Welding (i) Arc Metal Inert Gas Welding (MIG); Metal Active Gas Welding (MAG); Welding Tungsten Inert Gas Welding (TIG); Manual Metal Arc Welding or Stick Welding (MMA); Atomic Hydrogen Welding; Electro slag
Welding; Electro gas Welding; and Stud arc welding. ii) Gas (Air acetylene welding (AWS); Oxyacetylene welding (AAW); Welding Oxygen/Propane welding; Oxyhydrogen welding (OHW); and Pressure gas welding (PGW). Resistance spot welding (RSW) (iii) Resistance and Electric Resistance Welding (ERW). welding Thermit Welding. (iv) Thermit Welding Electron Beam Welding. (v) Electron Beam Welding Fire/Forged Welding (FW). (vi) Forged Welding Co extrusion welding (CEW); Cold (b) Pressure pressure welding (CW); Diffusion SolidWelding welding (DFW); Explosion State welding (EXW); Electromagnetic Welding pulse welding; Forge welding (FOW); Friction welding (FOW); Friction stir welding (FSW); Hot pressure welding (HPW); Hot isostatic pressure welding (HP); Roll welding (ROW); and Ultrasonic welding (US.). Main Welding Processes: Some of the Main Welding Processes, which are widely used in fabrication, and welding of pipe are given below:
Tig Welding
Electrode Welding
Mechanized Welding
Electric Resistance Welding (ERW): This process differs from the fusion welding process in the fact that no extra metal (filler metal) is added to the joint by any means. It is a group of welding
processes in which welding heat is generated by the resistance offered to the passage of an electric current through the parts being welded. This differs from the fusion welding process that no extra metal is added to the joint by means of filler wire or electrode. The resistance welding processes generally requires less skill on the part of the operators than in case with other type of welding. The resistance welding is a quantity- production process. Heat generated at weld will be proportional to I2 R, where ‘I’ is the current flowing through the material and R is the electrical resistance. The actual figure in kilocalories will be found to be I2 x R x T x 0.238 x 10-3, where, T being the time that the welding current flows and (0.238x10-3) is the factor for converting Joules to Kilocalories. The heating effect during the performance of a weld is proportional to: The Square of the heating current; the time of application of the weld; the electrical resistance of the materials to be welded. The total resistance is made up of the resistance of the material itself, the contact resistance between the electrode and the work piece and the contact resistance between the works pieces themselves. Of these, the contact resistance between the work pieces is the greatest, and can vary widely according to the cleanliness or surface condition and the mechanical pressure applied by the electrodes. Small pools of molten metal are formed at the weld area as high current (1000–100,000 A) is passed through the metal. In general, resistance welding methods are efficient and cause little pollution, but their applications are somewhat limited and the equipment cost can be high. Flux Cored Arc Welding (FCAW): Flux cored arc welding process is also a type of shielded metal arc welding. The welding time lost in changing the electrodes and the material loss as electrode stubs, necessitated the development of the Flux Core Arc Welding. In this process, the electrode is developed in long form, called “wire”. The arc protection is done with gas shielding either through welding nozzle or gas produced from the cored flux. The electrode is in tubular form, which contains the flux, de-oxidizer, scavengers and other alloying elements or denitrider. Argon, helium or carbon dioxide is used as shielding gas. Generally carbon dioxide (due point should be at least –450F) is used because of low cost. In this case, strong de-oxidizers are used in the electrode arc to produce a sound weld because CO2 is an active gas as compared to helium and argon. The electrode is in the form of a coil and the welding operation is automatic or semiautomatic. Advantages: The uninterrupted wires feeding gives high deposition rate; High deposition efficiency; High operating factors; Produces good radiography quality weld with good ductility and toughness; Cuts welding costs because of higher speed. Disadvantage: Irregularity in the structure of flux-cored electrode will introduce faults in weld deposits. Since the wire is tubular and usually has an open seam, the absorption of moisture by flux will result in weld porosity. In moving air (drafts) or wind; the protective gas shield may be disturbed causing weld defects. Flux-cored arc welding (FCAW) is automatic welding, which uses equipment and uses wire consisting of a steel electrode surrounding a powder fill material. This cored wire is more expensive than the standard solid wire and can generate fumes and/or slag, but it permits even higher welding speed and greater metal penetration. Gas Welding (GW) / Oxyfuel Gas Welding: The metals are heated with the help of gas such as oxygen-acetylene, oxygen-hydrogen or any other gas. Then a special pressure is applied to unite the metals together. This process is used for welding of Aluminium pipes or plastic pipes. This process is not used for metallic pipe welding. It is one of the most versatile welding processes, but in recent years it has become less popular in industrial applications. It is still widely used for welding pipes and tubes, as well as repair work. The equipment is relatively inexpensive and simple, generally employing the combustion of acetylene in oxygen to produce a welding flame temperature of about 3100 °C. The flame, since it is less concentrated than an electric arc, causes slower weld cooling, which can lead to greater residual stresses and weld distortion, though it eases the welding of high
alloy steels. Metal Inert Gas Arc Welding (MIG): Gas metal arc welding (GMAW), also known as Metal Inert Gas (MIG) welding, is a semi-automatic or automatic process that uses a continuous wire feed as an electrode and an inert or semi-inert gas mixture to protect the weld from contamination. Since the electrode is continuous, welding speeds are greater than for SMAW. In this process, the consumables travel through a nozzle and a tip before it strikes an arc with the work-piece. Gases such as 100% argon, 98% argon with 2% oxygen, 75% argon with 25% carbon dioxide, and 100% carbon dioxide shield the arc atmosphere. The smooth functioning of MIG welding depends on welding parameters, shielding gases, and the consumables. The welding parameters are amperage, voltage, feed of the wire, and speed of welding and flow rate of the shielding gas. The feed of the wire has to be adjusted to suit the speed determine the heat input. If these parameters are not synchronized, the welding does not perform well. There could be burn back fusing the tips, or there could be insufficient melting of the wire, resulting in improper fusion. If the gas pressure is insufficient, the metal gets oxidized, leaving inclusions and porosity in weld metal. There are two different techniques in MIG welding: Spray transfer & Droplet transfer / short-circuit type. In spray type, the liquid weld metal travels from the tip of the consumable in the form of tiny globules to the work piece. Spray transfer is achieved with higher current densities. In droplet transfer, the liquid metal travels in the form of droplets, and operates at lower current densities. Usually the droplet or short-circuiting technique is used in root pass welding, followed by spray transfer for the rest of the welding. Plasma Arc Welding: Plasma arc welding uses a tungsten electrode but uses plasma gas to make the arc. The arc is more concentrated than the GTAW arc, making transverse control more critical and thus generally restricting the technique to a mechanized process. Because of its stable current, the method can be used on a wider range of material thicknesses than the GTAW process and it is much faster. It can be applied to all of the same materials as GTAW except magnesium, and automated welding of stainless steel is one important application of this process. A variation of the process is plasma cutting, an efficient steel cutting process. Plastic welding: Plastic welding or Heat sealing is the process of welding plastic work pieces together. It is a very common process for joining plastics. A number of techniques are used for welding plastics. Hot gas welding, also known as hot air welding, is a plastic welding technique which is analogous to gas welding metals, though the specific techniques are different. A specially designed heat gun, called a hot air welder, produces a jet of hot air that softens both the parts to be joined and a plastic filler rod, all of which must be of the same or a very similar plastic. Welding PVC to acrylic is an exception to this rule. Hot air/gas welding is a common fabrication technique for manufacturing smaller items such as chemical tanks, water tanks, heat exchangers, and plumbing fittings. In the case of webs and films a filler rod may not be used. Two sheets of plastic are heated via a hot gas (or a heating element) and then rolled together. This is a quick welding process and can be performed continuously. A variety of heat sealers are available to join thermoplastic materials such as packaging films: Hot bar sealer, Impulse sealer, etc. Shielded Manual Arc Welding: This is a process wherein the coalescence of the metals is produced by heating them with an arc by passing electric current between the covered metal electrode and the work pieces. The shielding is obtained from the decomposition of electrode covering. Shielded metal arc welding (SMAW) is manual and versatile and is well suited to shop jobs and field work. Weld times are rather slow, since the consumable electrodes is frequently replaced and slag, the residue from the flux, is chipped away after welding by the welder every time. Furthermore, this process is generally limited to welding ferrous materials. The filler metal is obtained from the electrode wire.
The coated electrode provides a layer of slag, which protects the molten metal from harmful effects of atmospheric oxygen and other gases. The coating also provides a shield of inert gas, which completely envelops the welding area, and protects from atmospheric harmful effects. The purity of the weld metal is ensured fully. The coated electrode is made of a metal core wire surrounded (covered) by a thick coating applied on it. The composition of the coating is designed to stabilize the arc; to flux away any impurities present on the surface of the weld; to form a slag on the weld to protect the molten metal from atmospheric contamination and to slow the rate of cooling of the weld, reducing the chance of brittleness; to provide a smoother surface by reducing the ripples caused by the welding; to add certain desired constituents to the weld metal to compensate for the loss of any volatile allowing elements or any constituents lost by oxidation; and to speed up the welding operation by increasing the rate of melting. Both AC and DC current can be used for welding. For pipe welding, DC current gives good quality of weld. AC & DC have an important bearing on electrode and welding quality. Heat generated with DC is split into two parts in the ratio of 66 percent at positive pole and 33 percent at negative pole. Hence if the electrode is connected to the positive pole, it quickly becomes red-hot and welding is impossible. By connecting electrode to the negative pole and the work metal to the positive pole, the molten pool becomes the source of the higher heat content, the electrode remaining below the critical heat value. This is the main reason why AC is not used for welding the pipe because AC generates the heat at each pole equally and alternatively. Hence changing over the poles to electrode does not have any difference in case of AC. This is the reason why DC is preferred for welding of the pipe joint. The welding is done with DC at a voltage of 60 volts and current rating ranging from about 100 to 600 amps. The voltage is regulated automatically to meet the variation in the demand of the arc. One of the major factors affecting the quality of weld is the formation of oxides resulting from the tendency of molten metal to absorb oxygen from atmosphere. This is minimized (1) by the provision of slag forming fluxes in the electrode coating or (2) by providing a separate powder in case of submerged arc welding or (3) by blanketing the arc and molten metal area from the atmosphere with an inert gas, i.e. a gas which will not react or combined with heated metals. The most convenient and economical are helium, argon and carbon dioxide (CO2). This is the basic new principle of the newer “Shielded Arc Processes” being known as “Inert Gas Welding”. Argon is cheaper than helium and gives good performance and so it is widely used now days. Submerged arc welding (SAW): This is a process wherein the coalescence of the metals is produced by heating them with an arc or arcs between a bare metal electrode or electrodes and the work piece. A blanket of granular, fusible material on the work shields the arc and molten metal. Pressure is not applied. The filler metal is obtained the electrode or sometimes from a supplementary source. Submerged arc welding (SAW) is a high-productivity welding method in which the arc is struck beneath a covering layer of flux. This increases arc quality, since contaminants in the atmosphere are blocked by the flux. The slag that forms on the weld generally comes off by itself, and combined with the use of a continuous wire feed, the weld deposition rate is high. Working conditions are much improved over other arc welding processes, since the flux hides the arc and almost no smoke is produced. The process is commonly used in industry, especially for large products and in the manufacture of welded pressure vessels. Other arc welding processes include Atomic Hydrogen Welding, Electro slag Welding, Electro gas Welding, and Stud arc welding. Thermit Welding (TW): In this process, the heat is produced by the ignition of a mixture of finely produced aluminium and iron oxides (Thermit) and a pressure is applied to unite the two weld metals together. This is a type of fusion welding and used in workshop for production purpose. It is not used
for fabrication & erection of piping work. This chemical reaction reaches a temperature of 1, 400 °C (1,670 K). The reactants are usually supplied in the form of powders, with the reaction triggered using a spark from a flint lighter. The activation energy for this reaction is very high however, and initiation requires either the use of a "booster" material such as powdered magnesium metal or a very hot flame source. The aluminium oxide slag that it produces is discarded. The process employs a semi-permanent graphite crucible mould, in which the molten copper, produced by the reaction, flows through the mould and over and around the conductors to be welded, forming an electrically conductive weld between them. When the copper cools, the mould is either broken off or left in place. Alternatively, hand-held graphite crucibles can be used. The advantages of these crucibles include portability, lower cost because they can be reused, and flexibility, especially in field applications. The weld formed has higher mechanical strength than other forms of weld, and excellent corrosion resistance. It is also highly stable when subject to repeated short-circuit pulses, and does not suffer from increased electrical resistance over the lifetime of the installation. However, the process is costly relative to other welding processes, requires a supply of replaceable moulds, suffers from a lack of repeatability, and can be impeded by wet conditions or bad weather (when performed outdoors). Tungsten Arc-Inert Gas Welding (TIG)): Gas Tungsten Arc Welding (GTAW), or Tungsten Inert Gas (TIG) Welding, is a manual welding process that uses a non-consumable tungsten electrode, an inert or semi-inert gas mixture, and a separate filler material. In TIG welding, the arc is struck between the work piece and the non-consumable electrodes like thoriated tungsten for welding of ferrous materials and zirconiated tungsten for aluminium. The consumable wire is melted in the arc atmosphere and the inert gases like argon or helium or their mixture are used as shielded gases. TIG is extremely suitable for joining and making root pass welding in pipes, since the heat input in this process is minimal. TIG welds do not cause any undercuts or excessive penetration, and the distortion is the lowest of any welding process. TIG welds provide superior quality weld metal, but the productivity is low. This method is characterized by a stable arc and high quality welds, but it requires significant welder skill and can only be accomplished at relatively low speeds. GTAW can be used on nearly all weld able metals, though it is most often applied to stainless steel and light metals. It is often used when quality welds are extremely important, such as in bicycle, aircraft and naval applications. In this process the equipment consists of (1) the argon gas cylinder (2) the source of electricity, (3) control mechanism, (4) the welding torch that is either air-cooled or water-cooled. First, the purity of the gas is more important which should be 99.99 percent pure. Second, the rate of gas flow is also very important. For welding thin material, at low current, a small flow of gas gives adequate protection to small area of molten metal in the weld bead. For welding heavy gauge material, higher welding current and larger flow is required. Third, the arc stability is also important factor. Less gas is required for the more stable arc. Welding should be done in drought-free condition in order to minimize the gas consumption and also to ensure complete shrouding of the welding area. While welding, the cooling water, gas and power are switch on. The arc is struck between the tungsten electrode and the work piece. Immediately, the electrode reaches the operating temperature and starts melting the filler metal as well as the material to be welded. The joint can be made with or without filler metals. The filler rod moves ahead of the torch along the line of the joint. The torch is kept inclined at an angle of 15 0 maximum from vertical to allow the operator a clear view of the weld pool and to assist metal flow. The tip of the rod is kept just within the gas shield but sufficiently far from the arc to prevent excessive heating of the rod outside of the gas-shield area; otherwise the rod will become oxidized, leading to the difficulty of welding. As the welding proceeds, the end of the
rod is touched on to the leading part of the weld pool and at the same time, the torch is moved backward slightly. This movement is repeated at short intervals and should be quick but smooth to avoid creating turbulence in the argon shroud. The amount of metal transferred each time should be small so as to avoid chilling the weld pool and causing oxides inclusions. The rod should not be plunged into the weld pool while welding and should not leave the inert gas atmosphere at any time. The angle of the filler rod also should not be more than 15 0. During welding, the electrode must not touch the work piece or filler metal, otherwise the tungsten will be contaminated, the arc will become unsteady, and welding will be poor. The dark deposit will appear on weld. Holding a long arc on to a piece can burn off sight contamination of the electrode. In case of more severe cases, it is necessary to take the electrode out from the torch and grind a small piece off the tip. On completion of the welding, the arc is extinguished and the gas is left flowing sufficiently long for tungsten electrode to cool in the shielded atmosphere to avoid oxidizing. The welding sets are invariably designed for DC current. The use of DC with the tungsten electrode combines the advantages of reasonable penetration, moderate heating of the electrode, and adequate dispersal of the oxide film from the work surface. Torch with maximum rating of 75 up to 600 amps is available for manual welding. The 150 amps torch is air-cooled by natural convection and is intended for welding a material up to 3.5 mm thick. The 300 to 600 amps torch is water-cooled. Electrodes for the arc are generally a tungsten rod that is more expensive and require to safe guard the same properly. The tungsten rod should be protected from oxidation by flow of the argon gas for long even after the welding is completed to cool the electrode until there is no visible glow on tip of the rod. This prevents the deterioration of the rod by oxidation. Further, the tungsten rod should be protected from higher current than that for which it is intended. The higher current causes a high rate of burn-off and the risk of contamination of the weld pool with tungsten. At any moment, the electrode should not be allowed to touch the molten weld pool to avoid contamination of both electrode and the weld. This process of welding is widely used in piping fabrication and assembly. Arc-Inert Gas Welding: The Arc-Inert Gas Welding process enables the welding of metals e.g., Stainless steel, Nimonic, copper, Nickel, Cupronickel, Aluminium, Alloy steels and Bronze that are difficult to weld with ordinary process, There are two process of Arc-Inert Gas welding: (i) Tungsten Arc-Inert Gas Welding (TIG) and (ii) Self-Adjusting Consumable Electrode Arc-Inert Gas Welding. Weld Joint Edge Preparation: In common welding practices, the welding surface needs to be prepared to ensure the strongest weld possible. Preparation is needed for all forms of welding and all types of joints. Generally, butt welds require very little preparation, but some is still needed for the best results. Weld Joint edges can be prepared for butt joints in various ways, but the five most common techniques are oxyacetylene cutting (oxy-fuel welding and cutting), machining, chipping, grinding, and air carbon-arc cutting or gouging. Each technique has unique advantages to their use. For steel materials, oxyacetylene cutting is the most common form of preparation. This technique is advantageous because of its speed, low cost, and adaptability. Machining is the most effective for reproducibility and mass production of parts. Preparation of J or U joints is common prepared by machining due to the need for high accuracy. The chipping method is used to prepare parts that were produced by casting. The use of grinding to prepare pieces is reserved for small sections that cannot be prepared by other methods. Air carbon arc welding is common in industries that work with stainless steels, cast iron, or ordinary carbon steel. Prior to welding dissimilar materials, one or both faces of the groove can be buttered. The buttered layer can be the same alloy as the filler metal or a different filler metal that will act as a buffer between the two metals to be joined. Weld Joint - Heat-affected zone: The blue area results from oxidation at a corresponding
temperature of 600 °F (316 °C). This is an accurate way to identify temperature, but does not represent the HAZ width. The HAZ is the narrow area that immediately surrounds the welded base metal. The effects of welding on the material surrounding the weld can be detrimental depending on the materials used and the heat input of the welding process used. The thermal diffusivity of the base material plays a large role, if the diffusivity is high, the material cooling rate is high and the HAZ is relatively small. Conversely, a low diffusivity leads to slower cooling and a larger HAZ. The amount of heat injected by the welding process plays an important role as well, as processes like oxyacetylene welding have an unconcentrated heat input and increase the size of the HAZ. Processes like laser beam welding give a highly concentrated, limited amount of heat, resulting in a small HAZ. Arc welding falls between these two extremes, with the individual processes varying somewhat in heat input. To calculate the heat input for arc welding procedures, the following formula can be used:
Where Q = heat input (kJ/mm), V = voltage (V), I = current (A), and S = welding speed (mm/min). The efficiency is dependent on the welding process used, with shielded metal arc welding having a value of 0.75, gas metal arc welding and submerged arc welding, 0.9, and gas tungsten arc welding, 0.8. Underwater Welding: While many welding applications are done in controlled environments such as factories and repair shops, some welding processes are commonly used in a wide variety of conditions, such as open air, underwater, and vacuums (such as space). Shielded metal arc welding is also often used in underwater welding in the construction and repairs of ships, offshore platforms, and pipelines, but others, such as flux cored arc welding and gas tungsten arc welding, are also common. Welding in space is also possible. It was first attempted in 1969 by Russian cosmonauts, when they performed experiments to test shielded metal arc welding, plasma arc welding, and electron beam welding in a depressurized environment. Further testing of these methods was done in the following decades, and today researchers continue to develop methods for using other welding processes in space, such as laser beam welding, resistance welding, and friction welding. Advances in these areas may be useful for future endeavours similar to the construction of the International Space Station, which could rely on welding for joining in space the parts that were manufactured on Earth. Welding Safety Issues: Arc welding is safe with a welding helmet, gloves, and other protective clothing. Welding, without the proper precautions, can be a dangerous and unhealthy practice. However, with the use of new technology and proper protection, risks of injury and death associated with welding can be greatly reduced. Because many common welding procedures involve an open electric arc or flame, the risk of burns and fire is significant; this is why it is classified as a hot work process. To prevent them, welders wear personal protective equipment in the form of heavy leather gloves and protective long sleeve jackets to avoid exposure to extreme heat and flames. Additionally, the brightness of the weld area leads to a condition called arc eye or flash burns in which ultraviolet light causes inflammation of the cornea and can burn the retinas of the eyes. Goggles and welding helmets with dark face plates are worn to prevent this exposure, and in recent years, new helmet models have been produced that feature a face plate that self-darkens upon exposure to high amounts of UV light. To protect bystanders, translucent welding curtains often surround the welding area.
These curtains, made of a polyvinyl chloride plastic film, shield nearby workers from exposure to the UV light from the electric arc, but should not be used to replace the filter glass used in helmets. Welders are also often exposed to dangerous gases and particulate matter. Processes like flux-cored arc welding and shielded metal arc welding produce smoke containing particles of various types of oxides. The size of the particles in question tends to influence the toxicity of the fumes, with smaller particles presenting a greater danger. This is due to the fact that smaller particles have the ability to cross the blood brain barrier. Additionally, many processes produce fumes and various gases, most commonly carbon dioxide, ozone and heavy metals, which can prove dangerous without proper ventilation and training. Exposure to manganese welding fumes, for example, even at low levels (<0.2 mg/m3), may lead to neurological problems or to damage to the lungs, liver, kidneys, or central nervous system. Furthermore, because the use of compressed gases and flames in many welding processes poses an explosion and fire risk, some common precautions include limiting the amount of oxygen in the air and keeping combustible materials away from the workplace.
8.1
Welding Symbols
There are many methods of joining pipes. Welding being the easier and having less controlling factors is becoming more and more popular. Various welding processes have also opened new sites for designers to adopt various types of welding joint design. The accessibility and process deployment have caused in developing different types of joints and welds. To identify such types of joints and welds various welding symbols are adopted. A welding symbol consists of basic elements. These elements can be joined in various combinations to denote any of welds needed for any type of joint. Bureau of Indian Standard and American Welding Society have standardized these symbols and presented in composite sketches. These symbols quickly describe to the designer the weld that will develop the required joint. By adopting this system symbols, the engineer will ensure the followings: Correct welding instructions are transmitted to all concern. Prevent misinterpretation of instructions No delay in production Cost effect. Standard Welding Symbols for different Welds
Supplementary Symbols (IS: 813-1986)
Example of Application of Supplementary Symbols (IS: 813-1986)
Position of Symbol according to Reference Line
Fig: Standard Representation of Welds
Fig: Position of Welding Symbol
Fig: Preparation of Branch Connection
Method of Indicating Dimensions of Weld with Sketch as per IS: 813In a welding joint, the adjoining members may contact each other in several ways. More commonly used type of joints is a Butt, Lap, Corner, Tee, and Edge Joint. The general description of the joint geometry, however, does not define the weld joint configuration. A welded butt joint can be made in different ways, such as, square, double square, single bevel, single-V, double-V, J-V, U-V types of grooves. A T-connection can be made with double fillet or with a single or double bevel etc. Some typical welding symbols are explained below:
8.2
Welding Joint Types
The Common welding joint types are (1) Bevel Butt Welded Joint (2) Square Butt Welded Joint, (3) V Butt Welded Joint, (4) Lap Welded Joint, (5) T- 5 Welded Joint. Butt welding: Butt welding is a welding technique used to connect parts which are nearly parallel or bevelled but don't overlap. This type of weld is usually accomplished with an arc or MIG welder. Butt welds are prevalent in automated welding processes, such as submerged-arc welding, due to their relative ease of preparation. There are many types of Butt Joint geometries, such as, single welded butt joints, double welded butt joint, and open or closed butt weld joints. A single welded butt joint is the name for a joint that has been welded from one side. A double welded butt joint is created when the weld has been welded from both sides. With double welding, the depths of each weld can vary slightly. A closed weld is a type of joint in which the two pieces that will be joined are touching during the welding process. An open weld is the joint type where the two pieces have a small gap in between them during welding. Square Butt Joints: The square-groove is a butt welding joint with the two pieces being flat and parallel to each other. This joint is simple to prepare, economical to use, and provides satisfactory strength, but is limited by joint thickness. Bevel Butt Joints: Single-bevel butt welds are welds where one piece in the joint is bevelled and the other surface is perpendicular to the plane of the surface. Double-bevel butt welds are common in arc and gas welding processes. In this type both sides of one of the edges in the joint are bevelled. V- Butt Joints: Single-V butt welds are similar to a bevel joint. J- Butt Joints Single-J butt welds are when one piece of the weld is in the shape of a J that easily accepts filler material and the other piece is square. A J-groove is formed either with special cutting machinery or by grinding the joint edge into the form of a J. U- Butt Joints: Single-U butt welds are welds that have both edges of the weld surface shaped like a J, but once they come together, they form a U. Table: Work piece thickness limits per joint type Joint type Square joint Single-bevel joint Double-bevel joint Single-V joint Double-V joint Single-J joint Double-J joint Single-U joint Double-U joint Flange (edge of corner) Flare groove
Thickness limited To Up to 1⁄4 in (0.64 cm) 3⁄16–3⁄8 in (0.48–0.95 cm) Over 3⁄8 in (0.95 cm) Up to 3⁄4 in (1.9 cm) Over 3⁄4 in (1.9 cm) 1⁄2–3⁄4 in (1.3–1.9 cm) Over 3⁄4 in (1.9 cm) Up to 3⁄4 in (1.9 cm) Over 3⁄4 in (1.9 cm) Sheet metals less than 12 gauge All thickness
Typical Weld Joints
8.3
Weld Orientation
The welding of the base metals can be done oriented in any positions. The various welding Positions for Fillet-weld and Groove-welds are grouped in limited groups, which cover all the orientations of base metals and positions of the welder for performing welds. The various welding positions for fillet-welds and Groove-welds are given below:
8.4
Welding Accessories
Welding Gloves: Welding gloves are the specialized, highly-protective hand wear worn during material welding applications. They protect the welder's hands from high heat, molten metal, and flame while allowing for manual dexterity and movement of the fingers. Most welding gloves are made of heavy, thermally-insulating materials such as canvas, cotton, leather, metal and metal mesh, or wool. Welding gloves made of polyimide (polyphthalamide) fibres. Polyamides such as Kevlar thread are among the most thermally-stable organic materials, and are lighter and tougher than steel. Selecting welding gloves involves applications require abrasion, chemical or cut-resistant products. Others require protective hand wear that resists oil, heat, water, or radiation. Features for welding gloves include disposability, non-slip, non-stick, non-staining, sanitary, and hygienic. Welding Consumables: Generally, we use E6010 Electrodes (High Cellulose Electrode) for root welding for better penetration and E7018 (Low Hydrogen Electrode) for sound weld of carbon steel materials by SMAW process of Welding for construction of piping work. All low hydrogen type of electrodes shall be rebuked at 3500 C for 1-hour minimum and stored in ovens kept at 80-1000 C before use. All Electrodes are qualified before use and the qualification test records should be submitted to the client or the Representative of the Client for approval. The electrodes, filler wires and flux used shall be free from rust, oil, grease, earth and other foreign matter, which affect the quality of welding. The consumables for Mild steels welding are generally carbon-manganese type alloys, with carbon below 0.20%, manganese between 0.5% and 1.5%, and tensile strength 50,000 psi to 75,000 psi. The consumables for Low alloy steels welding contain carbon, manganese, chromium, molybdenum, and nickel and in some specific type’s vanadium and copper appear as alloying elements. Low alloy steels with chromium and molybdenum are meant for moderately high temperature applications, since they have high creep resistance. For still higher temperatures, ferritic and martensitic stainless steels are used. For low temperatures i.e. -50 degrees F, carbon and manganese steels are used. The consumables for welding low temperature steels are: Up to -30 degrees F Low carbon / high manganese type alloys (.05 C, 1.4 Mn) -30 Degrees F to -50 degrees F Manganese-molybdenum (1.4 Mn, .5 Mo) or Manganese-nickel (1.25 Mn, .5 Ni). Nickel and Nickel Alloy welding is different from welding other metals and alloys. Two characteristics contribute to this difference: (1) Nickel could form a tenacious viscous oxide during welding which restricts the weld ability and flow of the weld metal. (2) Nickel is highly susceptible to embrittlement by sulphur, phosphorus, lead and other low-melting substances. The weld metal flow problem can be reduced by: (1) Selecting an appropriate joint design. (2) Choosing the correct type of gas and gas flow rate to ensure proper protection from atmospheric oxygen. (3) Clean welding consumables, which do not contain any lubricants or oxides or contaminants. (4) Selecting a superior formulated covered electrode to ensure proper flow and cleanliness. The weld area on both sides of the weld joint must be tightly grounded to remove oxide from the surface. Inter-pass cleaning is essential to ensure complete slag removal as well as fusion between the weld beads. Weld joint designs used for nickel alloy welding should be different from those used for welding steels. The sluggish nature of the weld metal calls for more open joint, which will provide better
accessibility to the welder. Another characteristic of nickel alloy weld metal is the lower penetration, which makes the joints necessary to use smaller land at the root of the joint. For joining tubes and pipes, they should be purged and filled with inert gas before welding to avoid oxidation at the root. For manual welding, appropriate current range should be used to avoid overheating. Overheating of the electrode could result in loss of de-oxidizers and breakdown of the binder of the flux leading to defective welding. MIG welds calls for helium additions to argon to improve the wetting of the weld metal. For TIG welding, argon or argon-helium mixtures are generally used. Gas flow rates of 30 to 50 CFH are required to obtain high quality welds. With submerged arc welding, the flux has to be pre-baked before welding to reduce the chanced of weld defects due to moisture. A procedure test is generally required to assure that the proposed welding parameters and filler metals result in sound and acceptable chemical and mechanical properties of the welds. As the cleanliness of the welding consumables is of paramount importance, in-line cleaning systems have to be ensured for the requisite degree of cleanliness. The wires are so clean that we imprint out TIG wires with grade, heat number and size. Shielding and purging Inert Gas: Argon gas, used in TIG / GTA welding for shielding purposes, should be 99.995% pure. The manufacturer shall certify the purity of the gas. The rate of flow for shielding purposes should be established through procedure qualification tests. Normally, this rate varies between 12-20 CFH. Argon gas with a purity level of 99.995% should be used for purging also. Initial purging shall be maintained for sufficient period of time so that at least 4-5 times the volume between the soluble dams is displaced in order to completely remove the entrapped air. In no case should the initial purging period be less than 10 minutes. High gas pressure should be avoided. After initial purging, the flow of the backing gas should be reduced to a point where only a slight positive pressure prevails. For systems, which have a small volume (up to 1/2 cubic foot) to be purged, a gas flow rate of 6-CFH is usually adequate. System of larger volume requires higher flow rates and these should be established during procedure qualification tests. Dams, used for conserving inert gas during purging, should be removed after completion of the welding, and should be accounted for during piping welding. Wherever, removal of dams is not possible after welding, use of watersoluble dams should be used which will be washed away during flushing of the pipe. Equipment and Other Accessories: All the equipments for performing the welding, heat treatment, such as DC-Generators, Rectifiers transformers, thermocouples, gyro-meter, automatic temperature recorders (with suitable calibrated) shall be arranged by the piping Contractor. He should also make necessary arrangements at his own expense, for providing the radiographic equipments, radiographic films, processing equipment all other darkroom facilities and all the equipments/ Materials required for carrying out the dye penetration / magnetic particle test/ultrasonic testing for satisfactory and timely completion of the job. Edge Preparation: The edges to be welded must be prepared to meet the joint design requirements by any of the following recommended: Carbon Steel and Low Alloy Steels (Chromium 5% max.): Gas cutting, machining or grinding methods are used. After gas cutting, chipping or grinding removes iron oxides produced during cutting. High alloy steel (Chromium > 5%), Stainless steel and Nickel alloys: Plasma cutting, machining or grinding methods are used because these materials cannot be converted into iron oxide to cut it by gas cutting. After plasma cutting, cut surfaces are machined or ground smooth. Cleaning: The ends are properly cleaned to remove paint, oil, grease, rust, oxides, sand, earth and other foreign matters. The ends are completely dried before the welding commences. On completion of each run, grinding and chiselling remove craters, welding irregularities, slag. Wire brushes used
for cleaning stainless steel joints should have stainless steel wires and the grinding wheels used for grinding stainless steel should be of a suitable type, having stainless steel wires. Grinding wheels and wire brushes should be used for carbon steels and stainless steels separately. Alignment and Spacing: Components to be welded are aligned and spaced as per the requirements laid down in applicable code. Special care must be taken to ensure proper fitting and alignment of the inside edges when the welding is performed by GTAW process. Flame heating for adjustment and correction of ends is not permitted. Weather Conditions: During field welding using GTAW process particular care shall be exercised to prevent any air current affecting the welding process. Root Pass: Root pass should be welded with electrodes/filler wires recommended in the welding specification chart attached in the welding specification. Fillet welding, the welding should be done with consumables recommended for filler passes. The prefer size of the electrodes is 2.5 mm diameter (12 SWG) for root weld and 3.5 mm for filler pass but in any case not greater than 4.0 mm (8 SWG). Upward/uphill welding technique should be adopted for welding of pipe and the pipe is held fixed at 450 with its horizontal axis. The root pass of butt joints should be executed with care so as to achieve full penetration with complete fusion of the rot edges. Welding projection inside the pipe should be limited to 3 mm map. Welding shall be uninterrupted. While the welding is in progress care should be taken to avoid any kind of movement of the components, shocks, vibrations and stresses to prevent occurrence of weld cracks. Penning should not be used. Joint Completion: a) Size of the electrode should not exceed 4 mm in diameter for stainless steels and alloy steels used for low temperature applications. b) Two weld beads should not be started at the same point in different layers. c) But joints should be completed with a cover layer that would affect good fusion at the joint edges and a gradual notch free surface. d) Weld identification punch marks should be stamped clearly at each joint, just adjacent to the weld. Metal stamping shall not be used on thin pipe having wall thickness less than 3.5 mm. Suitable paint shall be used on thin pipes for identification of weld. Preheating: a) Welding should not be performed without preheating the joint to 100 C (500 F) when the ambient temperature is below 100 C. b) Preheating requirements for the various materials should be as per the Welding, Specification Chart attached. c) Preheating should be performed using resistance or induction heating methods. Preheating by gas burners, oxy-acetylene or oxy-propane gas mixtures, with neutral flame can also be carried when permitted. d) Preheating should extend uniformly to at least three times the thickness of the joint, but not less than 50 mm, on both sides of the weld joint. e) Preheating temperature should be maintained over the whole length of the joint during welding. Post Heating: In case of alloy steel materials such as Cr-Mo steels, if the post welds heat treatment is not performed immediately after welding, the weld joint and adjacent portion of pipe should be uniformly heated to 3000 C, at least 50 mm on either side of weld. This temperature shall be maintained for half an hour minimum, and then it should be wrapped in asbestos or insulation before allowing it to cool to room temperature. Post weld heat treatment as specified in the Welding specification chart should be carried out later on. Post Weld Heat Treatment methods: Post weld heat treatment should be done by heating in a furnace or by using an electric resistance or induction heating equipment. The portion outside the heated band should be suitably wrapped under insulation so as to avoid any harmful temperature gradient at the exposed surface of pipe, during the cycle of heat treatment. Temperature at the exposed surface should not be allowed to exceed 50% of the peak temperature for this purpose. The temperature
attained by the portion under heat treatment should be recorded by means of the thermocouple pyrometers. Adequate number of thermocouples should be attached to the pipe directly at equal space & location along the periphery of the pipe joint. The minimum number of thermocouples attached per joint shall be one up to 6” dia. Pipe, two up to 10” dia. and three for 12” dia and above pipe. Automatic temperature recorders, which have been suitably calibrated, should be employed for measuring & recording the temperature. The time-temperature graph should be submitted to client immediately on completion of S.R. The calibration chart of each recorder should be submitted to the client prior to starting the heat treatment operations for his approval. Welding Procedure Qualification: Welding procedure qualification shall be carried out in accordance with the relevant requirements of ASME Sec. IX latest edition or other applicable codes and the job requirements. Welder’s Performance Qualification: Welders shall be qualified in accordance with the ASME Section-IX or other applicable codes. Welding is a process where in coalescence (growth of two parts of metal into one part of metal) of the metals is produced either by melting and fusion to intermingled together or by pressure and force between two parts surfaces to form union into intimate contact.
8.5
Typical Metal Welding
Cast Iron: The welding of cast iron is an entirely different preposition from the welding of steel. It is because of (1) lack of ductility due to high proportion of carbon present in the steel, (2) any steel deposited on it picks up carbon and becomes carbon steel, which is liable to harden. It is weak in tension and withstands only small contraction stresses. It is liable to crack as a result of stresses produced when the work piece contracts after cooling. However, by taking a precaution, the welding of the cast iron is possible with the help of following electrodes. Ferrous (Ferritic) Electrodes having a low carbon content of about 0.1 per cent is used. Non-ferrous electrodes such as copper-nickel, Iron -nickel, Bronze, Monel or any other non-ferrous provide a solution of carbon pick up problems. The weld metals are not hardened appreciably with the absorption of carbon from the cast iron due to non-ferrous electrodes. The faces of the parts to be welded are cleaned properly before welding. The general rule for successful welding is (1) using small diameter electrode, and consequently a low current, (2) depositing metal in short runs and allowing each run to cool before making the new weld, (3) using block or step-back techniques and, (4) weaving as little as possible. It is advantageous to “peen” the weld lightly with hammer immediately after the weld deposition. This helps in the stress distribution and improves microstructure. Malleable Iron: prolonged heating of cast iron in the presence of iron oxide makes Malleable Iron. During this process, the surface is decarburised to a depth of 1.5 mm to 4.2 mm. Therefore, the surface is soft ductile iron. While welding, if it is heated to a temperature in excess of 7000C, malleable iron reverts back to white iron, which is very hard and brittle. So, the welding of malleable iron is done on surface only and in such a manner to apply lowest possible current by a small diameter electrode. Wrought Iron: the welding of the wrought iron is done in the same usual manner as for the steel. Galvanized Iron: Galvanized Iron is mild steel with a thin coating of zinc, and can be welded without difficulty with mild steel electrodes. It is advisable to clean off the zinc before starting the welding. The welding procedure is same as welding of steel.
8.6
Welding of Dissimilar Metals
The specific heat and the coefficient of expansion of the material play an important role while welding the dissimilar metals. The distortion is more in steel alloys of higher coefficient of expansion. This is the reason that the weld of two dissimilar metals may fail in service involving the thermal fatigue because of the fact that the two different materials differ significantly in coefficient of expansion and hence expand in different proportion with the same heat input. While welding of two dissimilar metals such as austenitic stainless steels and carbon steels or low alloy steels, excessive heat may produce the excess dilution of metals and rather hard and brittle zone adjacent to the base metals, which is, generally, mixed with martensitic formation. The undesirable effect like this may be reduced by proper electrode; preheating and post weld heat treatment of the weld joint during welding of the metals. During the diffusion of two dissimilar materials to be welded together during welding, the movement or migration of atoms across the bond takes place. While welding carbon steels and stainless steels, the diffusion of carbon atoms across the bond tends to have the most pronounced effect. The carbon migration is not considered sufficiently significant to create the harmful effect upon the service of the dissimilar metals joint below temperature 8000F. The carbon migration rate also depends on the extent of dissimilarity of the materials. This is the reason that the use of carbon steels in high temperature steam plants is restricted or limited to service below 7500F and use of carbonmolybdenum steels are limited below 8000F but this limit of working temperature is higher in case of chemical plants and refinery. So, while welding two dissimilar metals together, it is very important to select the filler metal or the material of the electrode with the coefficient of expansion in between the two material’s coefficient of expansion. Where welds are to be produced between carbon steels and alloy steels, preheat and post weld heat treatment requirements should be those specified for corresponding alloy steels and filler wire/electrodes should correspond to ER 70 S-G or ASW E-7018 type. For welds between two dissimilar Cr-Mo low alloy steels, preheat and post weld heat treatments shall be those specified for higher alloy steel and electrodes used shall correspond to those specified for steel of lower alloy content. For carbon steel or alloy steel to stainless welds, filler wire/electrodes E/ER-309/E-310/E Ni Cr Fe-3 should be used. 5.2.8 E LECTRODE CLASSIFICATION : During welding, when the metals are heated, it combines chemically with oxygen and nitrogen present in the atmosphere and forms oxides and nitrides of the metal that result in brittle, poor-quality of weld metal. For this reason, it is essential to provide some means of preventing the atmosphere from reaching the hot weld area. This is done either by shrouding the area with an inert gas or by covering the electrodes by suitable flux. The electrodes are coated or covered type, consisting of a metal core wire surrounded by a thick coating of flux applied by extrusion, winding, or other process. The success of welding operation depends on the composition of the coatings, which is varied to suit different conditions and metals. The welding electrodes are classified according to the followings: To stabilize the arc and enable the use of AC, if necessary. To flux away any impurities present on the surface being welded. To form a slag over the weld to protect the molten metal from atmospheric contamination, which slow the rate of cooling of the weld to reduce the chance of getting brittleness of the weld and to provide a smoother surface by reducing the ripples caused by the welding operation.
Type of current. Type of covering. Welding Position. Mechanical Properties of weld metal. The efficiency of all covered electrodes is impaired by dampness, and thus they must always be stored in a dry place. Weld metal properties vary widely according to the size of the electrode, amperage used, size of the weld beads, base metal thickness, and joint geometry, preheat and inter pass temperature, surface condition, base metal composition and dilution etc. Hydrogen has adverse effects on weld in some steel. One source of the hydrogen is moisture present in the electrode covering. For this reason, the proper storage, treatment, and handling of the electrode are required. Electrode Classification: As per AWS classification of electrode, the electrodes have been classified in different groups and designated as mentioned below: E XXYY M Where, First letter, “E”, “R” or “D” designate the method of manufacture of an electrode, such as, E – Solid extruded electrode, R –Reinforced electrode, and D –Dipped electrode. Second two digits “XX”, together, designates the tensile strength (minimum), in ksi, of the weld metal when produced. Third two digits “YY”, together, designates the welding position in which electrodes are usable, the type of covering and the type of welding current for which the electrodes are suitable. Last letter “M” designates an electrode intended to meet most mandatory requirements (greater toughness, lower moisture contents and mandatory diffusible hydrogen limits for weld metal). The coated electrodes provide a layer of slag, which protect the molten metal from the harmful effects of atmospheric oxygen and gases. The coating of the electrodes are so designed that the heat of the arc causes it to release large quantity of inert gas which completely envelops the welding area, thus shielding it from atmospheric gases. As a result of the combined protection of slag and shielding gases, the weld metals are insuring for purity. The welding electrodes have been, accordingly, grouped as mentioned below: 1. Deep-Penetration Electrodes: These are electrodes designed especially for a technique for making a joint by fusing together a considerable amount of the parent metal with the addition of comparatively little filler metal. The large amount of heat required for this technique is obtained by increasing the arc voltage of the electrodes by the use of cellulose materials in the coverings. Welding speed is also increased by this technique. E6010: These electrodes are characterized by a deeply penetrating, forceful, spray type arc and readily removable, thin, friable slag type electrode. Fillet welds usually have a relatively flat weld face and have a rather course, unevenly spaced ripple. Cellulose covering of the electrodes (E6010 and E6011) needs moisture level of 3% to 7% for proper operation. Therefore, the heating of the cellulose electrode is not done as because, heating above ambient temperature may dry them too much and adversely affect their operation. These position electrodes are recommended for all welding positions. E6010 electrodes have been designed for use with DC EP (Electrode Positive). The covering of E6010 electrode is called High-cellulose Sodium type. 2. Low Hydrogen Electrode(Best Quality): One of the causes of weld cracking is the presence of hydrogen in the weld metal. The coverings are designed specially to reduce the amount of diffusible hydrogen to avoid the cracking of the weld. This is called Low-Hydrogen Electrodes. The
characteristic of different AWS classified electrodes are as mentioned below: E7018: This is low hydrogen electrodes and has mineral coverings (inorganic coverings), which are high in limestone and other ingredients that contain low moisture. All low hydrogen electrodes are expected to have a maximum covering moisture limit of 0.6% or less. These types of coverings are “low in hydrogen contents”. The low hydrogen electrode is developed for welding of low alloy high-strength steels, some of which are high in carbon content. Other type of electrodes produces “hydrogen-induced cracking” in the same steels. These under bead crack occur in the base metal, usually just below the weld bead or in the weld metals too. These cracks are usually, because by the hydrogen absorbed from the arc atmosphere. Although, these cracks do not generally occur in carbon steels which have a low carbon content. Low hydrogen electrodes are also used to weld high sulphur and enamelling steels. Electrodes other than low hydrogen coverings give porous welds on high-sulphur steels. In order to give more satisfactory result by the low hydrogen electrodes, it is necessary to store and handle these electrodes carefully and should be heated in oven to the specified temperature before use. The electrodes are classified in detail and shown in Table Below: Table: Electrode Classification AWS Type of Classification Covering E6010 High cellulose sodium E6011 High cellulose potassium E6012 High titanium sodium E6013 High titanium potassium E6019 Iron oxide Tit. Potassium E6020 High iron oxide E7014 Iron powder, titanium
Welding Position F, V, OH, H
Type of Current DCEP
F, V, OH, H
AC/ DCEP
F, V, OH, H F, V, OH, H
E7015
F, V, OH, H
AC/ DCEP AC/ DCEP / DCEN AC/ DCEP / DCEN AC/ DCEN AC/ DCEP / DCEN DCEP
F, V, OH, H
AC/ DCEP
F, V, OH, H
AC/ DCEP
F, V, OH, H
DCEP
E7016 E7018
E7018 M
Low hydrogen sodium Low hydrogen potassium Low hydrogen potassium, Iron powder Low hydrogen iron powder
F, V, OH, H H-fillet, F F, V, OH, H
Notes: following abbreviations indicate the welding positions: F = Flat DCEP = Direct current, electrode positive H = Horizontal DCEN= Direct current, electrode negative
H-fillet = Horizontal fillet V = Vertical ac = alternating current OH = Overhead
8.7
Estimation of Welding Cost
When estimating the cost of welding, it is necessary to consider three things, (1) The cost of work preparation, (2) Cost of welding, and (3) cost of finishing the weld, i.e. the cost of inspection and acceptance of the welding. Welding Cost: The main items to be consider for calculation of the welding cost are, Determination of Electrode Consumption: The determination of electrode consumption is done as mentioned below, 1 Accounting for stubs differing in length from 50 mm: The standard consumption of electrode is given in the table by the manufacturer’s catalogue. Since the stub ends other than 50 mm length are very common while welding, these are to be accounted for by multiplying the quantity of standard electrode consumption by a correction factor. 2 Accounting for the Deposition Efficiency of the Electrode type used: The standard consumption of electrode is given in the table by the manufacturer’s catalogue. It is to be multiplied by the “correction factor to account for deposition efficiency”, which is given in the manufacture catalogue. 3 Accounting for abnormal Electrode Length: The electrodes of 3.15 mm, 4 mm and 5 mm diameters are produced also in 350 mm lengths, besides in standard lengths of 450 mm or vice-versa. When using the different lengths of electrodes than specified in the tables, the number of electrodes must be multiplied by the factor 1.33 or vice-versa. Calculation of Electrode Consumption: Another way of calculating the consumption of electrode is given below. The total Weight of the consumption of electrode is calculated by using following formula: WEIGHT OF THE CONSUMPTION OF ELECTRODE = 1.8 X W ----------------- (1) Where, W = Weight of Weld Metal taken from the Table or Graph. Table: Weight of Weld Metal in Kg/ meter for steel Plate Thickness in mm 10 20 30 40 50 60 70 80 90
Design of Weld Joint Single-V 1 2.5 4.68 7.8 12.1 18.14 23.4 31.98 41.38
Single-U 1 2.4 4.1 6.1 8.2 11.12 14 17.16 20.67
Double-V 0.75 1.56 2.93 4.49 6.63 9.75 12.48 17.16 21.45
Double-U 0.75 2.30 3.51 5.1 6.63 8.78 10.92 12.87 15.6
100 110
50.7 60.45
24.57 28.86
26.13 31.59
17.94 20.67
Determination of Welding Time: To find the welding time, the number of electrodes required for completing the welding of the joint should be multiplied by “melting time per electrode”. Determination of Current Consumption: The standard value of current consumption per electrode is given in the manufacturer’s catalogue. To find out the total current consumption, the total number of electrodes required for welding work should be multiplied by the “standard consumption of current for one electrode”. However, the cost of electric power consumption for welding can also be calculated as per the followings: Power Cost = (V x A)/1000 = (T x Cost per unit)/60x e. Where, V = arc voltage for the electrode used. A = Current. T= Time (in minutes) during which the arc is held. E= Overall efficiency of the machine. Labour Cost: The cost of Labour can be accessed from the standard norms of the welder performance given in the planning manual. Here, the standard output of one welder for a particular size and thickness, per day of 8 hours working, is given. Cost of Welding Accessories: The most satisfactory way of estimating the cost of welding accessories is to assign a definite life to each item and work out its price per hour. The “ life” of various accessories, based on experience, are given below: Table: Approximate life of welding accessories Accessories Generator Welding screen Welding glass Plain glass Gloves Chipping hammer Brush Electrode holder Flexible cable T.R.S. cable
Average life (in hour) 25 x 365 x 24 2400 2400 8 400 600 200 2400 2400 3600
8.8
Welding Defects:
Following defects are defined as per code: 1. Lack of Penetration: One of the most common defects is lack of penetration. It is also known as “Incomplete Penetration”. The depth of penetration into the parent metal is the depth to which the weld metal penetrates in it. It is generally 1.2 mm beyond the edge of the parent metal. If this is insufficient, the joint will be weaker than its design strength.
The cause of incomplete penetration is (I) too low welding current, (ii) Wrong polarity in case of a DC current, (iii) the skill and technique of welder, (iv) bad incorporation of tack weld (v) inadequate removal of slag, and (vi) use of too long arc. 2. Lack of Fusion: One of the most common defects is lack of Fusion. It is also known as “Incomplete Fusion”. The depth of Fusion into the parent metal or the weld metal is the depth to which the weld metal fused in it. It is generally 1.2 mm beyond the edge of the parent metal. If this is insufficient, the joint will be weaker than its design strength.
The cause of incomplete Fusion is (I) too low welding current, (ii) Wrong polarity in case of a DC current, (iii) the skill and technique of welder, (iv) bad incorporation of tack weld (v) inadequate removal of slag, and (vi) use of too long arc. 3. Porosity: Porosity consists of a group of small cavities caused by gas entrapment in the weld metal. It is an acute form of gas entrapped in the weld metal. When a tubular cavity is produced, it is known as piping, wormhole, or blowhole.
This term is usually employed when the hole comes to the surface of the weld. The porosity is because of formation of gas due to chemical reaction, the condition of electrodes, particularly the moisture content of electrodes, design of the electrodes, very low or too high welding current, Rust/scales/ galvanizing/oil/dampness on the work surface, sulphur content or steel contamination and impurities, high carbon steel etc. 4. Slag inclusion: The term “slag inclusion” or just “Inclusion” refers to the slag or other nonmetallic foreigner matters entrapped in the weld. The usual source is the slag formed by the electrode
coating or welding of a dirty surface. The slag is sometimes forced into the weld by arc. The main cause of slag inclusion are the use of too large electrode, Use of too high or too low welding current, inadequate removal of slag between deposition of successive runs, bad incorporation of tack weld, too long an arc and too high a speed of traverse. 5. Undercut: Undercut is a term denoting either burning away of the sidewalls of the joint recesses or reduction in the base metal thickness at the line where the last bead is fused to the surface.
Undercutting makes de-slagging difficult, and with a multi pass weld there is a strong possibility of slag entrapment on subsequent runs. Undercut considerably weakens the structure, particularly; with respect to fatigue endurance. The manoeuvring the electrode is one of the main causes of the undercut. Other causes of undercut are extreme differences in the heat capacity of two or more sections, forming the joint lead to undercut in the sections of lowest heat capacity, Damp electrodes, excessive welding current, heavy mill scales, excessive speed, wrong electrode angler, excessive weaving and the built up of too much heat etc.
6. Crack: Crack is one of the most serious defects. The formation of the crack is either in the weld itself or the adjacent parent metal.
Root Surface Concavity: Sometimes, while welding, the root surface is sucked inside the root edge and forms a cavity in the weld metal instead of protrusion as shown in the sketch.
8.9
Welding Distortion & Remedies
Followings are the certain basic facts, which is responsible for the distortion of the parts during welding: Heat affected Zone Defect: Graphitization is the process of breaking up iron carbide into iron and carbon and combination of carbon into graphite. Graphite formation is in the heat-affected zone parallel to the weld in steels. Small well-dispersed particles of graphite present in steels are not critical. But severe concentrations of graphite in the heat affected weld zone, parallel to the weld cause very severe embrittlement in the steel. The chain or clustered graphite severely reduces the ductility of the material as measured by bend test. Metals expand when heating and contract when cooling. Steel is elastic when stressed up to a point slightly below its “yield-point”. If stressed beyond the Yield-point, it “yields” or stretches, resulting in a plastic flow of metal or permanent deformation. If a piece of low-carbon steel is fully restrained from expanding longitudinally, an increase of 200 0F will cause it to expand by such an amount that it is stressed beyond its yield-point and plastic flow of metal takes place. PRINCIPLE OF “PLASTIC FLOW”, “RESIDUAL STRESS ” AND “DISTORTION”: Case 1: When end of the welding pieces are freed (not restrained) while welding, the expansion and contraction due to heating and cooling process during welding, are free, i.e. not restrained. In such case, there will not be any plastic flow, residual stress, warping, or distortion in the plate or pipe. Case 2: When both ends of the welding pieces are restrained (not free) during expanding while welding and are free (not restrained) during contracting, then a plastic flow of the base metal will occur during the welding by the heat produced and the material will warp near the weld joint. However, there will not be any residual stress as because the metals have contracted uniformly and freely without any restraint. Case 3: When both ends of the welding metals near the weld metal are restrained (not free) during expanding and contracting while welding, a plastic flow of the base metal occur during welding by the heat produced and the material will warp. A residual stress also exists in the heat-affected zone and weld metal In piping fabrication and assembly, the welding is done under case 3 condition. The weld metal and the metal in heat affected zone are restrained during expanding and contracting by the base metals outside the heat affected zone on each side of the weld. Thus, a narrow zone (heat affected zone) on each side of the weld undergoes plastic flow while welding. When this cool to room temperature, the weld metal and the base metal of the narrow zone (heat affected zone) on each side of weld contract and are restrained by the base metal outside the plastic zone (narrow zone). Therefore, a residual stress is set up in the weld metal as well as the base metal in heat-affected zone. The contracting zone (heat affected zone) is the predominating factor, causing the plate or pipes to close up ahead of the arc and warping take place. This causes the distortion of the work unless suitable precautions are taken. Therefore, before welding it is necessary to anticipate where the distortion will occurs and plans a welding sequence in such a way as to minimize or completely prevent its occurrence. Plastic deformation and residual stress in the welded structure are unavoidable. This is necessary to consider how this effect can be minimized.
If after a short weld (Tack Weld) is made, the weld metal is allowed to cool to reach a state of maximum contraction, another weld is made next to it. It will establish a transient expanding zone adjacent to it. The expansion zone will have less restraint and the contracting zone will be partially relieved. Thus the distortion is minimized and the stresses are reduced. This method of welding is termed as “skip welding”. This method is more effective when the number of skips is greater and the weld is shorter. Some residual stress will still exist but it will be within acceptable limit. Similarly, if the Single-V weld joint is welded with a small diameter rod or electrode, it will consume less current and hence less heat will be produced causing very little warping in the metals. An alternative method is to design unequal-V joint on each side of the plate. Weld the smaller-V first, with the minimum number of passes. The plate is then turned over and the large-V is welded. By this method, it is possible to obtain a joint, which is practically flat. Peening: Peening is another method of reducing distortion stress after welding. This consists the hammering of the joint with light and rapid blow with the help of the rounded edge of a hammer. Thus, it stretches the weld metal and counteracts the contraction of the cooled weld metal and, hence, reduces the internal stresses in the weld metal. Peening must be done when the metal is below red heat. If the metal is cold, Peening may cause cracking. Mechanical Method: Clamping of the parts is another method of preventing the distortion. The parts must be able to move slightly so that the contraction stresses are not strained; otherwise, severe internal stresses may be produced, sufficient, to cause the weld to crack. 5.2.12 WELDING CODE REQUIREMENTS Metallic piping materials and components fabrication, assembly is done by one or more of the following processes. While doing the piping work, the minimum code requirements as mentioned below, should be met for maintaining the quality and acceptance of the jobs. Each employer or organization, performing the weld, is responsible for maintaining the quality of weld and hence should qualify “welding procedure Specification” (WPS), Welders or Welding Operators Performance qualification as per Boiler and Pressure Vessel Code, Section-IX. They should maintain the “Welding Procedure Records” (PQR) and Welders Performance records with their individual identification number or symbols. Filler metal should be selected as per section-IX requirement. The internal and external surfaces to be thermally cut or welded should be cleaned. It should be free from dust, oil, rust, scale oxides or other material, which may be detrimental to either the weld or the base metal when heat is applied. End surface of the material to be welded should be reasonably smooth finished and free from slag from oxygen or arc cutting. Ends should be prepared as per requirement of WPS, PQR or ASME B16.25. The size and thickness of pipe end to be welded together should be same to maintain the alignment of the joint. Wherever necessary, weld metal should be deposited inside or outside of the component of less thickness to enable the satisfactory alignment and matching of the ends within dimensional limits of ASME/ANSI B31.3. Similarly, the external or internal surfaces of the components having more thickness should be chamfered or tapered for satisfactory alignment of the ends. Branch connections, which abut the outside surface of the run pipe, should be contoured for groove weld. Similarly, branch connection which are inserted through a run pipe opening should be inserted, at least, as far as the inside surface of the run pipe at all points as per ANSI B31.3 requirement. The run pipe openings at root of the branch contour should not be more than 3.2 mm or
5 times the thickness or branch pipe, whichever is less. The tack weld at the root of the joint should be made with the same filler metal, which will be used for the root pass welding. A qualified welder or operator should do the tack weld. Defective tack weld should be removed before start of the root pass weld. Peening is prohibited by the code on root pass or final pass of the weld. If there is impingement of rain, snow, sleet or excessive wind on the weld areas, welding should not be done. Welding or heat treatment of ball valve or other Teflon seating valves should be done such as to prevent the seat damage due to excessive heat. Slip-on flanges should be welded at both inside and outside ends. However, where the slip-on flanges are single welded, the welding should be done at the hub. A qualified welder should do seal welding. Seal weld should cover all the exposed threads. The fillet weld thickness of the reinforcement pad of branch connection should not less than 0.7 times the thickness of the branch pipe or 0.5 times the thickness of reinforcement pad plate. The reinforcement pad should be provided with a vent hole at the side (1) for testing the weld to reveal leakage in the weld between branch and run-pipe by air test and, (2) to allow venting during welding and heat treatment. If the ambient temperature is below 00C, the weld metal should be compulsorily preheated (up to minimum 25 mm beyond each edge of weld) to the specified preheat temperature as per table 330.1.1 of ASME/ANSI B31.3. Preheat temperature should checked by using temperature indicating crayons, thermocouple pyrometers or other suitable means. Preheat temperature of the dissimilar metals to be welded should be higher preheat temperature specified in the code. Preheating should be applied just before welding is resumed.
8.10
Welding Variables & Positions
The welding variables are the data or parameters in which a change may or may not affect the mechanical properties of the weld. The welding variables are categorized in three groups as mentioned below: Essential Variables: The essential variables are those variables in which a change is considered to affect the mechanical properties of the weld. What may be the essential variable for one welding process may be a supplementary-essential variable or non-essential variable for another process or may not be required at all for third process. Any change in essential variable requires re-qualification of WPS with new or additional PQR to support the changes in essential or supplementary essential variables, such as mentioned below: From one welding process to any other welding process or combination of welding processes. From a base metal of one P-Number to a metal of different P-Number. From filler metal of one A-Number to the different A-Number. Any change in the Position of welding. Any change in Preheat Temperature with more than 1000F. Any change in Post weld heat treatment condition or an increase of 25 per cent or more in total time at Post weld heat treatment temperature. Any change in multi-layer to single-layer cladding or vice versa Any change in type of current (AC or DC) or Polarity.
Any decrease in the distance between the weld fusion and final surface of the production. Supplementary Essential Variables: The supplementary essential variables are those variables in which a change in welding condition is considered to affect the Notch- Toughness properties of the weld. Any change in supplementary essential variable requires re-qualification of WPS. Non-Essential Variables: The non-essential variables are those in which any change in welding condition does not affect the mechanical properties of weld. Essential Variables: The Essential welding variables, which are required for each process of welding, are, mainly, divided into following eight groups: Joints: A change in the joint design such as V-Groove, U-Groove, and Single Bevel, Double Bevel or an increase in the fit-up gap, beyond that initially qualified. The joint configuration to be used in production of weld should be within limit as follows: Any change exceeding +-10 degree in the angle measured for the plane of either face to be joined, to the axis of rotation. Changes in cross sectional area of the weld joint greater than 10%. A change in outside diameter of the pipe greater than 10%. Base Metals: The base metals are grouped in different groups depending on the characteristics such as composition, weld ability and yield strength. As per ASME Section-IX, P-Numbers is assigned to base metals. In AWS D1.1, the base metals are divided into 5 groups and cover only carbon steel. As per API 1104, the base metals are divided into three groups. In DNV code, the base metals are divided into three parts and deals only with structural steels. In case of any change in P-Number to another P-Number or to any other base metal and thickness of base metal, requalification of WPS is required. Filler Metals: The filler metals are grouped into different A-Number depending on chemical composition of the weld deposit and the flux coatings. Any change in filler metal such as, the crosssectional area or the wire-feed speed greater than 10%, chemical analysis of weld metals, size of filler metals, F-Number, flux trade name, SFA specification filler metal classification, deletion or addition of filler metal, type of flux or composition of flux etc. need re-qualification of the WPS. Position: The WPS is qualified in a particular position as mentioned below: Groove Weld: Groove weld can be made in test material oriented in any one of the positions, such as 1G (Flat Position), 2G (Horizontal Position), 3G (Vertical Position), 4G (Overhead Position), 5G (multiple Position) or 6G (Multiple Position). Fillet Weld: Fillet weld can be made in test material oriented in any one of the positions, such as, 1F (Flat position), 2F (Horizontal Position), 3F (Vertical Position), 4F (Overhead Position), or 5F (Multiple Position). WPS is to be re-qualified for change of the positions as below: The addition of other welding position than already qualified. A change from any position to vertical position except 3G, 5G or 6G. III ) A CHANGE FROM UPWARD TO DOWNWARD OR FROM DOWNWARD TO UPWARD . Preheating: Preheating is used to minimize the detrimental effect of high temperature and severe thermal gradients inherent in welding. The necessity and temperature for preheating are specified in the engineering design code ANSI B31.3. The requirements and recommendations for preheating apply to all types of welding including tack welds, repair welds and seal welds of the threaded joint.
The preheat temperature is maintained in preheat zone of the weld which is extended at least 50 mm or three times the thickness whichever is more, beyond the edge of the weld. When two materials having different preheat temperatures requirements are to be welded together, then it is the higher preheat temperature shall be taken as preheat temperature for both the materials. When the ambient temperature is below 100C or below, welding should not be performed without preheating the joint to 100C. Preheating is performed using electric current through a resistance coil, induction-heating method, or by a gas burner using oxy-acetylene or oxy-propane gas mixtures. Preheating temperature is maintained over the whole length of the joint during welding. Table: Preheat Temperature Base metal P. No.
Weld Base metal metal Group A. No.
1
1
Carbon Steels
3
2,11
Alloy Steels Cr < = ½%
4
3
5
4,5
6
6
7
7
8
8,9
Alloy Steels ½%
U. T. S of Base metal (ksi) < 25 < = 71 > = 25 All All > 71 < 13 < = 71 > = 13 All All > 71 All All
Min. Temperature 0 C Require Recommend
149
10 79 79 10 79 79 --
All
All
177
--
All
All
All
All
--
10
All
All
--
10
Nom. Wall Thick. (mm)
--
--
149
Post Weld Heat Treatment: The heat treatment of the welded joint after completion of the welding is called Post Weld Heat Treatment. Post Weld Heat treatment is done to avert or to relieve the detrimental effects of high temperature and severe temperature gradient inherent in the welding. This is a process of heating the joint at a specified heat rate till the temperature is achieved and hold it at the same temperature for a specified period and then cool it at the specified cooling rate. The necessity and the PWHT temperature is specified in the engineering design code ANSI B31.3. The requirement and recommendations for PWHT apply to all types of welds including tack welds,
repair welds, and seal welds of the threaded joints. Heat treatment temperature is continuously checked and recorded on a graph through a machine with the help of thermocouple pyrometers attached adequately at all points on the surface of the parts equally spaced on the periphery of the pipes on either side of the weld. When heat treatment temperatures of two different metals are to be done together, it is the higher temperature of heat treatment is taken for PWHT. Heat treatment of the joint is done along with the base metal up to minimum 50 mm or three times the thickness extended on each side. Throughout the PWHT cycle, the portion outside the heated band should be suitably wrapped under insulation so as to avoid any harmful temperature gradient at the exposed surface of pipe. For this reason, the temperature at the exposed surface of pipe should not be allowed to exceed 4000C PWHT is done in furnace using oxy-acetylene or oxy-propane gas mixtures, by using an electric current resistance wire or induction-heating equipment. Uniform temperatures are maintained at all points of the portion being heat-treated. The weld zone and heat affected zone are insulated and wrapped with the insulation materials throughout the cycle of heat treatment to avoid any harmful temperature gradient the minimum numbers of thermocouples attached are one at every four inchdiameter length on periphery of pipe. Automatic temperature recorders are used for continuously recording f the temperature. This record of temperature is called PWHT charts/records/graphs. The identification marks of the joint heat-treated are written on the charts/records. After PWHT, the hardness of the weld metal is measured with Brinell hardness testing method and the hardness should meet the requirement of the code, ASME B31.3, Latest edition. Table: Post weld heat treatment temperature of metals Reference: ASME B31.3-1996, Table-331.1.1 P-No. & Base Metal
Wall Thick. (mm) & A-No. 1, CS < =19 1 >19 1 3, AS < = 19 Cr < = 2, 11 0.5% > 19 2, 11 4, AS < = 13 0.5% 3 < Cr < > 13 = 2% 3
5, AS
UTS (ksi)
Temp. Hold. Range Time 0 Min / C mm
Min. Hold. Time Hour
Brinell Hardness (Max.)
All
None
-
-
593 to 2.4 649 <=71 None -
1
-
-
-
All
593 to 2.4 718 <=71 None -
1
225
-
-
All
2
225
None
All
<=13
704 to 2.4 746
All
None
-
-
-
(2.25% < = Cr < = 10%) (< = 3% Cr & < = 0.15% C) > 3% Cr > 0.15%C 6, HAS Martensitic 6, HAS A240 Gr.429 7, HAS Ferritic 8, HAS Austenitic Notes: Gr. = Grade
4, 5
>13 4, 5 All 6 All 6
All
704
2.4
2
241
All
732 to 788 621 to 663
2.4
2
241
2.4
2
241
All 7 All 8, 9
All
None
-
-
-
All
None
-
-
-
All
CS = Carbon Steels; AS = Alloy Steels; HAS = High Alloy Steels; Cr = Chromium;
8.11 Welding Procedure Specification (WPS) A Welding Procedure Specification (WPS) is a formal document describing welding procedures. The purpose of the document is to guide welders to the accepted procedures so that repeatable and trusted welding techniques are used. A WPS is developed for each material and for each welding type used. Specific codes and/or engineering societies are often the driving force behind the development of a company's WPS. A WPS is supported by a Procedure Qualification Record (PQR or WPQR). According to the American Welding Society (AWS), a WPS provides in detail the required welding variables for specific application to assure repeatability by properly trained welders. The American Society of Mechanical Engineers (ASME) similarly defines a WPS as a written document that provides direction to the welder or welding operator for making production welds in accordance with Code requirements. Each Manufacturer or Contractor has to do the welding by his organization for construction of the piping. He must select and qualify the welding procedure, welder and welding operator engaged in the welding of pressure piping and vessels as per ASME/ANSI B31.3, SectionIX, AWS D1.1, API 1104 and DNV codes. The code Section-IX is very active and important documents to be referred for qualification purposes. Always, the latest edition of the code should be referred as it is reviewed and revised constantly by the committee. Out of the so many welding procedures described above, the most commonly used welding procedures are as mentioned below: Shielded Manual Metal Arc Welding (SMAW). Tungsten Inert Gas (TIG) Arc Welding. Submerged Arc Welding (SAW) Electric Characteristic: A change in the type of current or polarity, an increase in heat input, or an increase in volume of weld metal deposited per unit length of weld requires re-qualification of the WPS. Technique: Any change in the technique of welding, such as stringer bead to weave bead, oxidizing flame to reducing flame, orifice and nozzle size, forehand to backhand, cleaning method, back gauging method etc needs re-qualification of the WPS. Table: Welding Variables for Welder Performance (ASME Section - IX) Paragraph Brief of Variable
Essential Variables
Joints
SMAW X X
-Backing Pipe Dia.
#
SAW -X
GTAW X X
Base Metal Filler Metals
Positions
Gas Electrical
P-Number # Pipe Diameter # P-Number # F-No. 4X Limits F-Number # F-No. 2X Limits Weld Deposit (t ) # + Position Vertical Welding # (Uphill& Downhill) -Inert Backing Transfer Mode # Current or Polarity #
X X X X X -X X X
X X X ---X X --
X X X X -X X X X
---
----
X X X
Legend: # Change; - Deletion; + Addition Table: Welding Variables for Welding Procedure Specification (WPS) (Ref: ASME Section - IX) Item
Joints
Base metal
Variable’s List Essential Essential for (Any Change Variables Notch Toughness in Following) SMAW SAW TIG SMAW SAW TIG Groove Design Fit-up gap Flux or ferrule Root spacing Bevel angle > 10 deg. Cross section > 10% OD > =-10% P-Number Penetration Group Number T Limits T/t Limits > 20 X cm T Qualified X T Pass > 12 X mm
X X X
X
X X
X
X X
X X
Nonessential
SMAW SAW TIG X X X
X
X
X
Filler Metal
P-No. Qualified P-No. 9/10 Size
X
X
X
X
X
X X
F-Number X A-Number X Diameter Dia. > 6 mm Flux/Wire Class Alloy Flux AWS Class +- Filler +Supplemental +Sup. Powder Alloy elements Flux Designation T X Flux Type Position + Position Position Vertical Pos. Hand
X X
Preheat
X
Temp.
PWHT
Gas
Decrease > X 1000F Preheat Maintenance. Increase>1000F (IP) PWHT X T & T Range T Limits X Single, Mixture Or Percentage Flow Rate +- Backing < Flow Rate
X X X
X
X X X X
X
X X X X X X X
X X X
X
X X
X
X
X X
X
X
X
X
X
X
X
X
X
X X X X X X
Composition Shielding or Trailing Elect. I or > Heat Charact- Input eristics +- Pulsing I Type I or I&E Range Tungsten Electrode TechString/Weave nique Orifice, Cup or Nozzle size Method Cleaning Method Back Gauge Oscillation Tube-Work distance Multi to Single Pass Single to multi electrodes Closed to out chamber Electrode Spacing Manual or Automatic +- Peening
X X X
X
X
X
X
X X X
X
X
X X
X
X
X
X
X
X
X
X
X
X X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
SAMPLE OF PROCEDURE QUALIFICATION SPECIFICATION (WPS) Customer:_____________________ Contractor___________________ PQR NO.____________ Date________ WPS No.______ Date__________ Rev. No.________________ Date_________________ Welding Process:________ Type: Automatic/Manual _______________________
Joint Detail: _________________________ Joint Design_________________ Backing Yes/No.______________ Backing Material Spec. ________ (A sketch may be attached to illustrate joint design detail, e.g. root space, weld groove detail & weld layers and bead sequence, e.g. for notch toughness procedures, for multiple process procedures etc.)
Base Metals Detail: P NO .____ G ROUP NO ._____ G ROUP NO ._________ Material Spec._____________ Spec._______________ Base Metal Thickness Range: Plate: Groove______________ Pipe: Groove______________ Others: _____________________
TO P.NO . _____ Material
Fillet_________________________ Fillet_________________________
Filler Metals: Spec. No. (SFA)__________________________________________ AWS No. (Class)_________________________________________ F.No. __________________________________________________ A.No. __________________________________________________ Size of filler Metals_______________________________________ Weld Metal Thickness Range: Groove_________________________________________________ Fillet__________________________________________________ Electrode-Flux (class)_____________________________________ Flux Trade Name________________________________________ Consumable Insert_______________________________________ Other__________________________________________________
P OSI TI ONS : PWHT: Position of groove___________ Temperature Range_________ Welding Progression: Up/Down; Time Range_______________________________________ Position of fillet_________________________________________________________________
Preheat: P REHEAT:___________________ GAS : __________ Preheat Temperature (Min.) ____________ Gas ______________ Rate __________ Interpass Temperature(Max.)___________ Shielding ___________________________________ Nature of Preheat_______________ Traiting ___________________________________________ Backing ______________________________________________________________________ Electrical Characteristics: Current AC/DC Polarity____________________________________________ Electrodes/Tungsten Electrode Size &Type____________________________________________ Amps.(Range)________________ Volts (Range)________________ (Amps Volts range shall be recorded for each electrode size, position and thickness etc.) Mode of Metal Transfer for GMAC________________________________________________ Electrode Wire feed speed range____________________________________________________
Technique: String or Weave Bead_____________________________________ Orifice or Gas Cup Size___________________________________ Initial and Interpass Cleaning (Brush, Grinding etc.)_____________ Method of Back Gouging__________________________________ Oscillation______________________________________________ Contact Tube to Work Distance_____________________________ Multiple or Single Pass (Per Side) ____________________________ Multiple or Single Electrodes_______________________________ Travel Speed (Range) ______________________________________ Peeing________________________________________________ Other_________________________________________________ _________________________________________________ Tensile Tests Specimen No. Width Thickness
Area Ultimate load in Kg. UTS Failure location & Nature Guided-Bend Tests Type and Figure No. Result Toughness Tests Specimen No. Notch Location Specimen Size Test Temp. Impact value Drop WT. Break Weld Tests Result: Satisfactory/Unsatisfactory Penetration into Parent Metal: Yes/ No Macro Result: _________________________________________________ Other Tests Type of Test____________________________________________ Deposit Analysis_________________________________________ Others_________________________________________________________________________ Welder’s Name:_________________________________________ Test Conducted By_____________ Lab. Test No.______________ WE CERTI FY THAT THE STATEMENTS I N THI S RECORD ARE CORRECT AND THE TEST WELDS WERE PREPARED , WELDED & TESTED I N ACCORDANCE WI TH THE REQUI REMENT OF SECTI ON IX OF ASME CODE. Contractor: ________________Inspector:____________Date:_____
8.12 Welding Procedure Qualification Records (PQR) Procedure Qualification Record (PQR) is a record of the welding data used to weld a test coupon. The PQR is a record of variables recorded during welding of the test coupons. It also contains the test result of the tested specimens. The recorded variables normally fall within a small range of actual variables, which is used during production of weld. Welding procedure qualification shall be carried out in accordance with the relevant requirements of ASME Sec. IX latest edition or other applicable codes and the job requirements The completed PQR is a document with all recorded essentials and supplementary essential variables for the welding process used during the welding of test coupons. Non-essential variables are also recorded as per option of the manufacturers or contractors. The manufacturer and the authorized inspector certify that the information in the PQR is a true record of the variables that was used during welding of the test coupons. The resulting tensile strength, bend test or macro etch test (as required) results are in accordance with Section-IX. In the oil and gas pipeline sector, the American Petroleum Institute API 1104 standard is used almost exclusively worldwide. API 1104 accepts the definitions of the American Welding Society code AWS A3.0. When more than one welding process or filler metals are used to weld the test coupons, the approximate weld metal thickness of each process or filler metals are recorded in PQR. Any changes in the PQR are not permitted as per code. The information recorded in the PQR is in the form of a format to fit the need of the contractors. The PQR is kept in a record file to be made available as and when required. SAMPLE OF PROCEDURE QUALIFICATION RECORDS (PQR)
Customer: _____________________Contractor_________________ PQR NO.____________ Date________ WPS No.______ Date______ Rev. No.________________Date____________ Welding Process: ___________________Type: Automatic/Manual ________________________
Joint Detail: Joint Detail Joint Design_________________ Backing: Yes/No. Backing Material Spec.________ (A sketch may be attached to illustrate joint design detail, e.g. root space, weld groove detail & weld layers and bead sequence, e.g. for notch toughness procedures, for multiple process procedures etc.)
Base Metals Detail:
P NO .____ G ROUP NO ._____ TO P.NO ._____G ROUP NO ._________ Material Spec. _____________ Material Spec. _______________ Base Metal Thickness Range: Plate: Groove______________Fillet_________________________ Pipe: Groove______________Fillet_________________________ Others:
Filler Metals: Spec. No. (SFA)__________________________________________ AWS No. (Class)_________________________________________ F.No. __________________________________________________ A.No. __________________________________________________ Size of filler Metals_______________________________________ Weld Metal Thickness Range: Groove_________________________________________________ Fillet__________________________________________________ Electrode-Flux (class)_____________________________________ Flux Trade Name________________________________________ Consumable Insert_______________________________________ Other__________________________________________________
P OSI TI ONS : PWHT: Position of groove___________ Temperature Range_________ Welding Progression: Up/Down; Time Range________________ Position of fillet__________________________________________
Preheat: P REHEAT: G AS : Preheat Temp. (Min.) ____________ Gas Rate Interpass Temp. (Max.)___________Shielding Nature of Preheat_______________Traiting Backing Electrical Characteristics: Current AC/DC Polarity___________________ Electrodes/Tungsten Electrode Size &Type_________________ Amperes (Range)________________Volts (Range)________________ (Amps Volts range shall be recorded for each electrode size, position and thickness etc.) Mode of Metal Transfer for GMAC________________________ Electrode Wire feed speed range___________________________
Technique: String or Weave Bead_____________________________________ Orifice or Gas Cup Size___________________________________ Initial and Interpass Cleaning (Brush, Grinding etc.)_____________ Method of Back Gouging__________________________________ Oscillation______________________________________________ Contact Tube to Work Distance_____________________________ Multiple or Single Pass (Per Side)____________________________ Multiple or Single Electrodes_______________________________ Travel Speed (Range)______________________________________ Peeing________________________________________________ Other
Tensile Tests
Specimen No. Width Thickness Area Ultimate load in Kg. UTS Failure location & Nature Guided-Bend Tests Type and Figure No. Result Toughness Tests Specimen No. Notch Location Specimen Size Test Temp. Impact value Drop WT. Break Weld Tests Result: Satisfactory/Unsatisfactory Penetration into Parent Metal: Yes/ No Macro Result: _________________________________________________ Other Tests Type of Test____________________________________________ Deposit Analysis_________________________________________ Others____________________________________________________________________________
Welder’s Name: _________________________________________ Test Conducted By_____________Lab. Test No.______________ WE CERTI FY THAT THE STATEMENTS I N THI S RECORD ARE CORRECT AND PREPARED , WELDED & TESTED I N ACCORDANCE WI TH THE REQUI REMENT OF CODE. Contractor:________________Inspector:____________Date:_____
THE TEST WELDS WERE SECTI ON
IX
OF
ASME
8.13
Welder Performance Qualifications (Certification)
Welders shall be qualified in accordance with the ASME Section-IX or other applicable codes. Welder certification, (Welder Qualification) is a process which examines and documents a welder’s capability to create welds of acceptable quality following a well defined welding procedure. Welder certification is based on specially designed tests to determine a welder's skill and ability to deposit sound weld metal. The tests consist of many variables, including the specific welding process, type of metal, thickness, joint design, position, and others. Most often, the test is conducted in accordance with a particular code. The tests can be administered under the auspices of a national or international organization, such as the American Welding Society (AWS), or American Society of Mechanical Engineers (ASME), or Manufacturer’s standards and requirements as well. Welders can also be certified in specific welding related professions: for example, American Welding Society certifies welding inspectors and welding instructors, and the American Society of Mechanical Engineers certifies high capacity fossil fuel fired plant operators and several other professions. Most certifications expire after a certain time limit, and have different requirements for renewal or extension of the certification. Welder qualification is performed according to AWS, ASME and API standards. Once a welder passes a test (or a series of tests), their employer or third party involved will certify the ability to pass the test, and the limitations or extent they are qualified to weld, as a written document (welder qualification test record, or WQTR). This document is valid for a limited period (usually for two years), after which the welder must be retested. The essential and supplementary-essential variables for welder performance tests are as mentioned below: Joints: Same as WPS. Base Metals: Same as WPS. Filler Metals: This is the essential variable on which the ability the welder to perform the weld depends. The usability characteristics of the filler metals, fundamentally, determine the ability of welders to make satisfactory welds with given base metals. Filler metals are grouped in different groups based on the weld deposit and flux coating like Low Hydrogen, Cellulose, and Rutile coating. Position: Various positions are defined in the codes referred above. In these positions the movement of the welder is restricted. The skill of the welders varies in different positions of welding. Hence, the ability of the welder is determined whether they can produce sound weld in these difficult positions. Electric Characteristic: A change in the type of current or polarity, an increase in heat input, or an increase in volume of weld metal deposited per unit length of weld requires re-qualification of the Welder’s Performance. Technique: Any change in the technique of welding, such as stringer bead to weave bead, oxidizing flame to reducing flame, orifice and nozzle size, forehand to backhand, cleaning method, back gauging method etc needs requalification of the Welder’s Performance. Tests Required for Welders Performance Qualification Tests Required for Welder Performance Qualification is different than the required for WPS and are mentioned below: Guided-Bend Test for groove-weld joint. Fillet-Weld Test such as “Macro etch Test” and “fracture Test” for Fillet-weld joints. Radiographic Examination is to substitute for the mechanical tests for groove-weld. Acceptance criteria-The guided-bend tests and the Fillet-weld tests acceptance criteria are the same as above. The radiographic Examination is judged unacceptable when the radiograph exhibits any
imperfection in excess of the limits specified below: Linear Indications: Any type of crack or zone of incomplete fusion or penetration. Any elongated slag inclusion which has a length greater than 3 mm for t up to 10 mm, 1/3 times t for t over 10 mm to 56 mm, or 19 mm for t over 56 mm. Any group of slag inclusions in line that have an aggregate length greater than t in a length of 12t. Rounded Indications: The rounded indications in the weld should not be more than 20 % of the wall thickness or 3 mm, whichever is less. Maximum number of rounded indications should not be more than 12 in 150 mm length of weld. SAMPLE OF WELDER/WELDING OPERATOR PERFORMANCE QUALIFICATION (WPQ)
Welder’s Name_________________ Welder’s Name____________ Welding Procedure Used____________ Type__________________ Identification of WPS done by welder________________________ Spec. Of Base Metals Welded________________ Thickness_______ Variables used for process of Welding: Actual value Range Qualified P.No. _________ To P.No. _______ Pipe (Dia.)_____ Plate (thickness)__ Filler (SFA)_____ Backing ------------Classification____ Filler F.No._____ Filler Metal_______________ CONSUMABLE INSERT_______________ WELD THI CKNESS _______________ WELD POSI TI ON_______________ P ROGRESSI ON UPHI LL/ DOWNHI LL BACKI NG G AS _______________ GMAW TRANSFER MODE__________ GTAW WELDI NG CURRENT________ WELDI NG MACHI NE VARI ABLES : Direct/Remote Visual Control Automatic Volt Control Automatic Joint GUIDED BEND TEST RESULTS:
Bend Test Type_________________ Side_____________________ (Trans. R & F) Type___________ (Long. R & F) Result____________ Visual Examination Result_________________________________ Radiography Test Results__________________________________ Fillet Weld Test Results:___________________________________ Fracture Test (Length & % of Defect______________________ Macro Test Fusion_______________________________________ Fillet Leg Size___________ Concavity / Convexity___________ Welding Test Conducted By___________________________ Mechanical Test Conducted By_________________________ We certify that the statement in this record are correct and that the test coupons were prepared, welded, and tested in accordance with the requirement of section IX of the ASME Code. Contractor_________________ Inspector_____________________ Date____________
8.14
WPS / PQR Qualification tests
The following mechanical tests are carried out to determine the metallurgical properties of the weld in welding procedure qualification: Tensile Test: Tensile tests are used to determine the ultimate strength of groove-weld joints. The tensile tests are done on the specimens in one of the following types: Reduced section of the plate or pipe. Turned Specimens Full-Section specimens for pipe with outside diameter of 3” or less. Acceptance Criteria- The tension test is acceptable subject to the tensile strength of the specimen is not less than the followings: The specified minimum tensile strength of base metal. The tensile strength of the weaker of the two metals. If the specimen breaks in the base metal outside the weld or fusion line. Guided Bend Test: Guided-bend Tests are used to determine the degree of soundness and ductility of groove-weld joint. The bend tests are performed on the specimen in the following types: Transverse Side Bend Test. Transverse Face Bend Test. Transverse Root Bend Test. Acceptance criteria- The guided-bend specimens should not have any open defects in the weld or heat affected zone, exceeding 3.1 mm, measured in any direction on the convex surface of the specimen after bending. Fillet-Weld Tests: The fillet weld test is done to determine the size, contour and degree of soundness of fillet welds. The Fillet-weld tests are carried in the following manners: Fracture Tests. Macro-Examination. Acceptance criteria- i) The welded surface should not have any cracks or incomplete root fusion. The sum of the length of inclusions and porosity visible on weld surface should not be more than 9 mm or 10% of the quarter section. (ii) One face of each cross section should be smooth finished and etched with nitric acid to have a clear definition of weld metal and heat affected zone. Visual examination of the cross section of the same should have complete fusion and free from cracks. There should not be a difference, in the leg of fillet, more than 3 mm. The weld should not have a concavity or convexity greater than 1.5 mm. The etching solutions suitable for carbon steels and low alloy steels are a below: -Equal parts of Hydrochloric Acid and Water by volume at boiling point. -One part of Nitric Acid and three parts of Water, by volume at room temperature. Notch-Toughness Tests: Notch-Toughness tests are used to determine the notch toughness of the weld. Stud-Weld Tests: In these tests, the deflection bend, hammering, torque, tensile, and a macro examination are performed in accordance with the requirement of ANSI B31.3 for acceptability of the stud welds. Welding Inspector Certification: There are also schemes to independently certify welding inspectors and related specialities. Some notable schemes established by personnel certification bodies are those of the American Welding Society. The American Welding Society offers the
following programs: Certified Associate Welding Inspector; Certified Welding Inspector; Senior Certified Welding Inspector and Certified Radiographic Interpreter.
9 Piping Inspection
9.1
General
The owner has the responsibility to verify and inspect, either themselves or by Third Party, the piping works to the extent necessary to be satisfied and till the conformation of the job to the requirement of the code and the engineering design. For this purpose, the authorized inspector should have access to any place where piping work is in progress. They should have right to audit any examination; any method of examination and any certificate or record. Successful and consistent application of nondestructive testing techniques depends heavily on personnel training, experience and integrity. Personnel involved in application of industrial NDT methods and interpretation of results should be certified, and in some industrial sectors certification is enforced by law or by the applied codes and standards. Any item if found defective beyond the acceptance limit shall be repaired or replaced. In case of sot or random examination, if any item reveals a defect then two additional samples of the same kind (welded by the same welder) should be marked for the same kind of examination as a penalty. If the penalties marked items are found acceptable, then the all the above items are acceptable. However, if any defect is found in one or the both then two further samples of the same kind should be examined for each defective item. When all the defective items thus marked are found acceptable then all the items are accepted in Toto. But if any item thus marked found defective, all the above marked items are to be replaced with new and should be inspected again.
9.2
Applicable Codes and Standards
ASTM A34: ASTM A275: ASTM A340:
ASTM A456:
Standard Practice for Sampling and Procurement Testing of Magnetic Standard Practice for Magnetic Particle Examination of Steel Forgings Standard Terminology of Symbols and Definitions Relating to Magnetic ASTM A370: Standard Test Methods and Definitions for mechanical testing of Steel products. ASTM A388: Ultrasonic Examination of Heavy Steel Forging ASTM A435: Straight-Beam Ultrasonic Examination of steel Plates Specification for Magnetic Particle Inspection of Large Crankshaft forgings ASTM A577: Ultrasonic Angle-Beam Examination of steel Pates ASTM A578: Straight-Beam Ultrasonic Examination of plain and clad
steel ASTM A673:
ASTM A966: ASTM A967:
Plates for special Applications Standard Specification for Sampling Procedure for Impact Testing of ASTM A745: Ultrasonic Examination of Austenitic Steel Forging ASTM A751: Test Methods, Practices and Terminology for chemical Analysis of steel products. Standard Practice for Magnetic Particle Examination of Steel Forgings Standard Specification for Chemical Passivation Treatments for Stainless ASTM E3 : Preparation of Metallographic Specimens. ASTM E7: Terminology Relating to Metallographic Examination of
Metal Pipe and Tubing. ASTM E8: Test Method for Tension Testing of Metallic materials (Metric) ASTM E10: Test Method for Brinell hardness of Metallic Materials ASTM E18: Test Method for Rockwell Hardness and Rockwell Superficial Hardness of Metallic Materials ASTM E21: Test Method for Elevated Temperature Tension Tests of metallic Materials ASTM E23: Test Method for Notched Bar Impact Testing of Metallic Materials ASTM E45: Test Method for Determining the Inclusion Content of Steel ASTM E92: Test method for Vickers Hardness of metallic Materials ASTM E94: Guide for Radiographic Testing ASTM E103: Test Method for Rapid Indentation Hardness Testing of
Metallic Materials ASTM E110: Test Method for Indentation Hardness of Metallic Material by Portable Hardness Tester ASTM E114: Practice for Ultrasonic Pulse-Echo Straight-beam Examination by the contact method ASTM E125: Reference photographs for Magnetic Particle Indications on Ferrous Casting ASTM E142: Method for Controlling Quality of Radiographic Testing ASTM E155: Reference Radiographs for inspection of Aluminium and Magnesium Castings ASTM E165: Test Method for Liquid Penetration Examination ASTM E186: Reference Radiographs for Heavy walled (51 mm to 114 mm) Steel Castings ASTM E190: Test Method for Guided Bend Test for Ductility of weld ASTM E213: Practice for Ultrasonic Examination for Metal Pipe and Tubing ASTM E243: Practice for Electromagnetic (Eddy-Current) examination of copper and Copper- Alloy Tubes ASTM E272: Reference Radiographs for high Strength copper-Base and Nickel-Copper Alloy Castings ASTM E280: Reference radiographs for Heavy walled (114 to 305 mm) Steel Castings ASTM E290: Test Methods for Bend testing of Material for ductility ASTM E292: Test Methods for conducting Time-for-Rupture Notch Tension Test of Materials ASTM E310: Reference Radiographs for Tin Bronze Castings ASTM E340: Test Method for Macro etching Metals and Alloys ASTM E376: Practice for Measuring Coating Thickness By Magnetic – Field or Eddy-Current Test Method ASTM E381: Macro etching Testing Steel Bars, Billets, Blooms and Forging ASTM E384: Micro hardness of materials ASTM E407: Micro etching Metals and Alloys ASTM E432: Guide for Selection of a Leak Testing Method ASTM E433: Reference Photographs for Liquid Penetration Inspection ASTM E446: Reference Radiographs for Steel Castings (51 mm) Thickness ASTM E479: Guide for preparation of a Leak Testing Specification
ASTM E515:
Test Method for Leaks Using Bubble Emission
Techniques ASTM E543:
Practice for Agencies Performing Non-destructive
Testing ASTM E592: Standard Guide to Obtainable ASTM Equivalent Penetrameter Sensitivity for Radiography of Steel Plates ASTM E689: Reference Radiographs for Ductile Iron Castings ASTM E709: Guide for Magnetic Particle Examination ASTM E740: Practice for Fracture Testing with Surface-Crack Tension ASTM E747: Test Method for controlling quality of radiographic testing using Wire Pentameters ASTM E801: Standard Practice for Controlling Quality of Radiological Examination of Electronic Devices ASTM E837: Test Method for determining Residual Stresses by the HoleDrilling Strain-Gage Method ASTM E1003: Test Method for Hydrostatic Leak Testing ASTM E1030: Test method for Radiographic Examination of metallic Castings ASTM E1032: Test Method for Radiographic Examination of Weld. ASTM A1047: Standard Test Method for Pneumatic Leak Testing of Tubing ASTM A1058: Standard Test Methods for Mechanical Testing of Steel Products - Metric ASTM E1161: Standard Practice for Radiological Examination of Semiconductors and Electronic Components ASTM E1316: Terminology for Non-destructive Examinations ASTM E1351: Production and Evaluation of Field metallographic Replicas ASTM E1417: Practice for Liquid Penetration Examination ASTM E1444:
Practice for Magnetic Particle Examination ASTM E1457: Test Method for measurement of Creep Crack Growth
Rates in Metals ASTM E1595: Practice for evaluating the performance of Mechanical Testing Laboratories ASTM E1648: Standard Reference Radiographs for Examination of Aluminium Fusion Welds ASTM E1735: Standard Test Method for Determining Relative Image Quality of Industrial Radiographic Film Exposed to X-Radiation from 4 to 25 MeV ASTM E1774: Guide for Electromagnetic Acoustic Transducers (EMATs) ASTM E1815: Test Method for Classification of Film Systems for
Industrial Radiography ASTM E1816: Practice for Ultrasonic Examinations using Electromagnetic Acoustic Transducer (EMAT) Techniques ASTM E1817: Standard Practice for Controlling Quality of Radiological Examination by Representative Quality Indicators (RQIs) ASTM E1820: Test Method for Measurement of Fracture Toughness ASTM E1842: Test Method for Macro-Rockwell Hardness Testing of Metallic Materials
9.3
Levels of certification
Most NDT personnel certification schemes listed above specify three "levels" of qualification and/or certification, usually designated as Level 1, Level 2 and Level 3 or (Level I, Level II, Level III). The roles and responsibilities of personnel in each level are generally as follows: Level 1: Level I technicians are qualified to perform only specific calibrations and tests under close supervision and direction by higher level personnel. They can only report test results. Normally they work following specific work instructions for testing procedures and rejection criteria. Level 2: Level II engineers or experienced technicians who are able to set up and calibrate testing equipment, conduct the inspection according to codes and standards instead of following work instructions and compile work instructions for Level 1 technicians. They are also authorized to report, interpret, evaluate and document testing results. They can also supervise and train Level 1 technicians. In addition to testing methods, they must be familiar with applicable codes and standards and have some knowledge of the manufacture and service of tested products. Level 3: Level III are usually specialized engineers or very experienced technicians. They can establish NDT techniques and procedures and interpret codes and standards. They also direct NDT laboratories and have central role in personnel certification. They are expected to have wider knowledge covering materials, fabrication and product technology. Inspection: Prior to initial operation, each piping work materials shall be examined, inspected, or tested in accordance with design code requirements. The joints not included in the examination are accepted if they pass the leak test or hydrostatic test. Material Inspection: Materials and components should be inspected for any damage during handling and their certificates should be checked for conformation to the specifications and free from defects. Fabrication Inspection: The fabrication work of each welder or operator should be examined by radiography. Flange/Threaded Joint Inspection: The assembly of flanged, threaded, bolted and other kind of joints should be inspected for conformation to the applicable code requirements. Support/Alignment/Spring Pull Inspection: The checking of alignment, supports, and cold springs during erection of piping should be done strictly as per the drawings. Drawings Deviation Inspection: The erected piping should be examined for evidence of defects that would require repair or replacement and other kind of any deviations from the extent of the design. Welds Inspection: 100% visual examination of the longitudinal welds should be done, which require having a joint factor Ej of 0.90. 100% examination: All of the designated piping work including all components should be completely examined. Random examination: A percentage of the designated piping work should be examined. Spot examination: A specified partial of the designated piping work, i.e., a part of the length of all shop-fabricated welds should be examined. Random Spot examination: A specified partial examination of a percentage of a designated piping work should be examined.
9.4
Destructive Examinations & Test
Destructive Testing is a method in which the materials are destroyed during testing: Followings are the different kind of Destructive Testing: 6.4.1 Physical Test: Followings are the different type of Physical tests, which are carried out: Universal Testing Machine Test: Physical Testing is done with the help of 100T “Universal Testing Machine”. Tensile Test at room temperature or at elevated; Tensile Test with Stress-Strain curves; Bend Test; Flattening: Flaring Test; Proof Load Test; Load Test; Compression Test; Shear Test; Wedge Test; and Minimum Leak Path Test. Metallographic Test: Macro Examination; Micro Examination; and Micro Photographs. Miscellaneous Test: Impact Test; Mercury Nitrate Test; Coating Thickness Test; Thermal Shock Test; Water Absorption/Bulk Density Test; Ferrite Content Test; and Temper Bend Test. 6.4.2 Chemical Analysis: Following Chemical Compositions like: Ferrous; Carbon, manganese, Silicon, Phosphorous, Nickel, Sulphur, Vanadium, Chromium, Molybdenum, Copper, Titanium etc. 6.4.3 Inter Granular Corrosion (IGC) Test (ASTM-262): Oxalic Acid Etch Test; IGC Ferric Sulphate-Sulphuric Acid Test (120 Hrs.); Nitric Acid Test (240 Hrs.); Nitric-Hydrofluoric Acid Test; Copper Sulphate-Sulphuric Acid Test (24 Hrs); and Copper Sulphate-Sulphuric Acid Test (72 Hrs). 6.4.4 ASTM G-36-Chloride Stress Corrosion Test: Mg Cl 2 Test and Ca Cl 2 Test. 6.4.5 NACE Test (TM-0177 & TM-0284): Hydrogen Induced Cracking (96 Hrs.); Sulphide Stress Corrosion Cracking Test (720 Hrs. 2400 C); Sulphide Stress Corrosion Cracking Test (720 Hrs. 9000 C, 16 bars); and Sulphide Stress Corrosion Cracking Test (720 Hrs. 1200 C, 20 bars). 6.4.6 Pitting Corrosion Test: Pitting Corrosion Test (ASTM G-44 at 2200 C); and Pitting Corrosion Test (ASTM G-44 at 500 C). 6.4.7 Specialized Test: Metallographic Examination; Fatigue Test; Stress Rupture Test; CTOD Test; Failure Investigation; and Material/Metallurgical Improvement Study.
9.5
Non-Destructive Test
Piping Inspection also includes Non-destructive testing (NDT) methods, which are a wide group of examination techniques used in piping industry to evaluate the properties of a material, weld defects or piping system without causing damage. Non-destructive testing (NDT) is also called Nondestructive examination (NDE), Non-destructive inspection (NDI), and Non-destructive evaluation (NDE). NDT does carry the inspection of pipe without permanently altering the piping being inspected. NDT methods are a highly-valuable technique that can save both money and time in defects evaluation, troubleshooting, and research. Common NDT methods include but not limited to (i)Visual Inspection; (ii) Radiography Test (RT); (iii) Ultrasonic (UT); (iv) Magnetic-particle inspection (MT or MPI); (v) Liquid penetrant Test (LPT)/ Dye penetrant Test (DPT) ; (vi) Eddy-current testing (ECT); (vii) Magnetic flux leakage testing (MFL); (viii) Hardness testing; (ix) Leak testing (LT) or Leak detection; (x) Hydrostatic Pressure testing; and (xi) Bubble testing. Therefore choosing the right method and technique is an important part of the performance of NDT. Ultrasonic Examination or Radiography should be used to examine, fully, the first circumferential butt or mitre groove welds of each welder or operator before put in production. The Socket welds and Branch connection welds, which are not radiograph, should be examined by Magnetic Particle or Liquid penetration test methods. The longitudinal welds, which required the joint factor Ej of 0.90, of each welder or welding operator should be radiograph. DP/MP Test should examine the welded branch connection welding or repair work before instalment of the reinforcement pad or saddles. The welding work shall be examined at least 10% for the Normal Fluid Service conditions where lower level of weld quality is permitted allowing some lack of penetration, and 100% for the Severe Service conditions where full penetration of weld deposits are required. Followings inspection should be carried out during assembly of piping work: Major Types of Non-Destructive Test Methods Inspection Equipment Defects Method Required (i) Visual Magnifying Surface flaws like cracks, glass; Weld porosity, unfilled craters, gauge; Rule; slag inclusions surface Straight edge. undercut under welding, over welding, poorly formed beads, misalignments, improper fit up (ii) X-ray or Gamma Interior flaws like Radiographic units. Film and cracks, porosity, processing blow holes, slag facilities. inclusions, Fluoroscopic incomplete root viewing equipment. penetration, undercut, icicles, and burn through.
(iii) Magnetic Particle
Equipment, Magnetic powders (dry or wet), fluorescent for viewing under ultraviolet light. (iv) Eddy current Eddy current Equipment (v) Magnetic Magnetic flux flux leakage leakage testing tool
Excellent for detecting surface discontinuities like surface cracks.
Micro cracks
detect corrosion and pitting in pipe or vessels, Surface cracks not readily visible to the unaided eye. Excellent for locating leaks in weldments.
(vi) Liquid Kits containing Penetrant fluorescent or dye penetrant and developers. A source of ultraviolet light, if fluorescent method is used. (vii) Instruments Evaluates ductility, Hardness elastic stiffness, Test plasticity, strain, strength, toughness, visco-elasticity, and viscosity (viii) Special Surface and Ultrasonic commercial subsurface flaws equipment (either including those too pulse-echo or small. transmission type). Especially for detecting subsurface lamination-like defects. (ix) Hydrostatic and Pressure Cracks not readily Leak Test Pump, Dial visible to the unaided Gauges, eye. Excellent for Magnifying locating leaks in glass, Soap weldments. powder, Chalk.
9.6 N.D.T Examination Requirements M A T E R I A L
P No.
T E M P. L I M I T 0 C
R A T I N G
PPG. C L A S S
TYPE OF WELD & NDT-EXAMINATION
Kg/ Cm2 RADIOGRAPHY
Carbon steel
AUSTENITIC SS
HDPE
CUPRONICKEL
Carbon steel
1
-29
150# 10.55
8
186 -29 _
150# 10.55
-
186 -20 _
150# 10.55
34
50 -29 _
1
60 -29 _
A3A, A3Y, J2A, J3A, J5A A3K
G I R T H BW --
M I T E R BW 10% Root
V I S U A L
100%
--
10% 100% ROOT
A1Z, A4ZA5Z
--
10% 100% ROOT
150# 10.55
--
--
10% 100% ROOT
150#
A1A A6A A8A A9A A10AA13AA14AA20A
50%
50% ROOT
100 %
Carbon steel L
Carbon steel
Carbon steel (Killed)
Carbon steel (Killed)
Carbon steel
Carbon steel
Carbon steel (Killed)
C _ 0.5 Mo
0.5 Cr _ 0.5 Mo
2 Cr _ Mo
C _ 0.5 Mo (IBR)
1
426 -29 _
150#
A2A
50%
50% ROOT
100 %
1
426 -29 _
150#
--
100%
--
100 %
1
426 -45 _
150 _
A4A, B4A, D4A
100%
--
100 %
1
200 -45 _
600# 150 _
A4A, B4A, D4A
100%
--
100 %
1
200 -29 _
600# 150#
--
100%
--
100 %
1
426 -29 _
300 _
B1A, B6AB9A, B13A D1A, D6A
100%
--
100 %
1
426 -29 _
600# 150 _
B2A, D2A
100%
--
100 %
3
426 -29 & above
600# 150 _
A1B, B1B, D1B
100%
--
100 %
-29 & above
600# 150 _
--
100%
--
100 %
-29 & above
600# 150 _
A1D, B1D, D1D
100%
--
100 %
-29 & above
600# 150 _
D2B
100%
--
100 %
3
4
3
1.2 Cr _ Mo IBR
5% Cr
3.5 Ni
Austenitic SS
Austenitic SS
Aluminium & Aluminium Alloy Copper & Copper Alloy
Aluminium Bronze
4
5
9
8
8
-29 & above
600# 150 _
D2B
100%
--
100 %
-29 & above
600# 150 _
--
100%
--
100 %
-29 & above
600# 150 _
A1H, B1H, D1H
100%
--
100 %
-29 & above
600# 150 _
A1K, A1M, A1N, A6K
100%
--
100 %
-29 _
600# 300 _
B1K, B1M, B3M, B1N, B6N
100%
--
100 %
600# 150#
--
100%
--
100 %
21_25
500 -29 _
31
500 -29 _
150#
--
100%
--
100 %
35
500 -29 _
150#
--
100%
--
100 %
Above 600# Above 600# Above 600#
E1A,F1A
100 %
--
E2A,F2A
100 %
--
--
100 %
--
100 % 100 % 100 %
150 _
A4F, A4G, B4F, B4G
100 %
--
Carbon steel
1
500 All
Carbon steel IBR C _ 0.5 Mo
1
All
3
All
5 Cr _ 9 Cr Mo
5
All
100 %
600# 12 Cr (410)
6
All
All
--
100 %
--
Carbon steel (Killed) 1 _ 2 Cr (IBR) Ni Alloy
1
100 %
--
F2D
100 %
--
45
All
Above 600# Above 600# All
--
4
Unto –45 All
--
100 %
--
Carbon steel
1
All
All
--
100 %
--
0.5 _ 9 Cr Mo
3,4,5
All
All
B12A--
100 %
--
12 Cr (410)
6
All
All
--
100 %
--
3.5 Ni
9
All
All
--
100 %
--
Austenitic SS
8
All
All
--
100 %
--
Austenitic SS
8
-80 & Below
150 _
A2K, B2K, D2K
100 %
--
--
100 %
--
B4K, B5K
100 %
--
100 %
--
600# All Above 600# Above All 500 All All
Austenitic SS
8
Austenitic SS
8
Carbon Steel
1
0.5 _ 9 Cr Mo
3,4,5
All
All
100 %
--
3.5 Ni
9
All
All
100 %
--
41,42,43
All
All
D18P
100 %
--
8
All
All
B12K D18K B5M
100 %
--
R
PPG.
Ni-Alloy Austenitic SS
P
T
100 % 100 % 100 % 100 % 100 % 100 % 100 % 100 % 100 % 100 %
100 % 100 % 100 % 100 % 100 %
100 % 100 %
TYPE OF WELD & NDT-
A T E R I A L
Carbon steel
AUSTENITIC SS
HDPE
CUPRONICKEL
Carbon steel
Carbon steel L
No.
E M P. L I M I T 0 C
A T I N G
EXAMINATION
C L A S S
Kg/ Cm2
1
-29
8
186 -29 _
150# 10.55
-
186 -20 _
150# 10.55
A1Z, A4ZA5Z
--
--
10% 10% (ROOT/ ROOT FINAL)
34
50 -29 _
150# 10.55
--
--
--
10% 10% (ROOT/ ROOT FINAL)
1
60 -29 _
150#
--
10% 50% (ROOT/ ROOT FINAL)
1
426 -29 _
150#
--
10% 50% (ROOT/ ROOT FINAL)
426
150# 10.55
A3A, A3Y, J2A, J3A, J5A A3K
DYE PENETRATION/ MAGNETIC PARTICLE P A B R I T R E P T A D E M N U N C C SW T. H E R SW SW BW --10% 10% (Root & Root Final) --10% 10% (ROOT/ ROOT FINAL)
A1A A6A A8A A9A 10% A10AA13AA14AA20A
A2A
10%
Carbon steel
1
-29 _
150#
--
20%
--
20% (ROOT/ FINAL)
--
-45 _
150 _
A4A, B4A, D4A
20%
--
20% (ROOT/ FINAL)
--
1
200 -45 _
600# 150 _
A4A, B4A, D4A
20%
--
20% (ROOT/ FINAL)
--
1
200 -29 _
600# 150#
--
20%
--
20% (ROOT/ FINAL)
--
1
426 -29 _
300 _
B1A, B6AB9A, B13A D1A, D6A
20%
--
20% (ROOT/ FINAL)
--
1
426 -29 _
600# 150 _
B2A, D2A
20%
--
20% (ROOT/ FINAL)
--
3
426 -29 & above
600# 150 _
A1B, B1B, D1B
20%
--
20%
--
-29 & above
600# 150 _
--
20%
--
20%
--
-29 & above
600# 150 _
A1D, B1D, D1D
20%
--
20%
--
-29 & above
600# 150 _
D2B
20%
--
20%
--
-29 & above
600# 150 _
D2B
20%
--
20%
--
426 Carbon steel (Killed)
Carbon steel (Killed)
Carbon steel
Carbon steel
Carbon steel (Killed)
C _ 0.5 Mo
0.5 Cr _ 0.5 Mo
2 Cr _ Mo
C _ 0.5 Mo (IBR)
1.2 Cr _ Mo IBR
1
3
4
3
4
5% Cr
3.5 Ni
Austenitic SS
Austenitic SS
Aluminium & Aluminium Alloy Copper & Copper Alloy
Aluminium Bronze
5
9
8
8
-29 & above
600# 150 _
--
20%
--
20%
--
-29 & above
600# 150 _
A1H, B1H, D1H
20%
--
20%
--
-29 & above
600# 150 _
A1K, A1M, A1N, A6K 20%
--
20%
--
-29 _
600# 300 _
B1K, B1M, B3M, B1N, 20% B6N
--
20%
--
21_25
500 -29 _
31
500 -29 _
150#
--
20%
--
20%
--
35
500 -29 _
150#
--
20%
--
20%
--
Above 600# Above 600# Above 600#
E1A,F1A
100 % 100 % 100 %
10 % 10 % 10 %
100 %
--
100 %
--
100 %
--
150 _
A4F, A4G, B4F, B4G
100 %
10 %
100 %
--
--
100 %
10 %
100 %
--
Carbon steel
1
500 All
Carbon steel IBR C _ 0.5 Mo
1
All
3
All
5 Cr _ 9 Cr Mo
5
All
12 Cr (410)
6
All
600# 150#
--
20%
--
20%
--
600# All
E2A,F2A --
Carbon steel (Killed) 1 _ 2 Cr (IBR)
4
Unto –45 All
Above 600# Above 600#
45
All
All
--
Carbon steel
1
All
All
--
0.5 _ 9 Cr Mo
3,4,5
All
All
B12A--
12 Cr (410)
6
All
All
--
3.5 Ni
9
All
All
--
Austenitic SS
8
All
All
--
Austenitic SS
8
-80 & Below
150 _
A2K, B2K, D2K
Ni Alloy
1
600# All Above 600# Above All 500 All All
-F2D
Austenitic SS
8
Austenitic SS
8
Carbon Steel
1
0.5 _ 9 Cr Mo
3,4,5
All
All
3.5 Ni
9
All
All
41,42,43
All
All
D18P
8
All
All
B12K D18K B5M
Ni-Alloy Austenitic SS
-B4K, B5K
100 % 100 %
10 % 10 %
100 %
--
100 %
--
100 % 100 % 100 % 100 % 100 % 100 % 100 %
10 % 10 % 10 % 10 % 10 % 10 % 10 %
100 %
--
100 %
--
100 %
--
100 %
--
100 %
--
100 %
--
100 %
--
100 % 100 % 100 % 100 % 100 % 100 % 100 %
10 % 10 % 10 % 10 % 10 % 10 % 10 %
100 %
--
100 %
--
100 %
--
100 %
--
100 %
--
100 %
--
100 %
--
9.7 Weld Imperfections and Acceptance Limit Depth of Incomplete Penetration Cumulative length of Incomplete Penetration Depth of Lack of Fusion Cumulative length of Lack of Fusion Size and distribution of Internal Porosity Slag Inclusion (Individual length) (Individual width) (Cumulative length) Depth of Undercut Surface Roughness
1 mm or 0.2 Tw 38 mm in any weld length of 152 mm 0.2 Tw 38 mm in any weld length of 152 mm 1.25D
0.2 Tw/3 2.5 mm or 0.2 Tw Tw in any weld length of 12T 1 mm or 0.25 Tw 500 min. Ra per ASME B46.1 Depth of Root Surface Concavity Total joint thickness, including weld reinforcement Tw Height of Reinforcement or 0.24 Tw Internal Protrusion Crack Not Allowed Note: 1. Random 10% of any NDT test means the testing of one joint out of every ten joints or less of weld completed by the same welding procedure or operators or both. 2. Random 20% of any NDT test means the testing of one joint out of every five joints or less of weld completed by the same welding procedure or operators or both.
9.8
Inspection and Testing
Instruments The flowing instruments are used for inspection in piping: Pressure Gauges: The pressure gauge used in pressure testing should preferably have dials graduated over range of about double the intended maximum pressure for testing, but in no case should the range be less than 150% nor more than 400% of the test pressure. Standard Test Gauge (Pressure Gauge) of Make: W & T or Budenberg; Dial size: 8.5” diameter; Pressure Range: 0 to 10 kg/cm2; 0 to 50 kg/cm2; 0 to 100 kg/cm2; 0.22 kg/cm2 and Accuracy: 0.2% FSD (Full Scale Division). It is used for Leak testing of the piping system. It should be calibrated regularly at every 6 months. Precision Test Gauge: Make: W & T or Budenberg; Range: 0 to 20 Torr; Accuracy: 0.2% FSD (full Scale Division); It is used for Leak testing of the piping system. It should be calibrated regularly at every 6 months. Dead Weight Tester (Oil Operated): Make: Budenberg; Range: 1 to 550 kg/cm2; Accuracy: 0.03% of the range; Range: 1 to 70 kg/cm2; Accuracy: 0.05% of the range. Dead Weight Tester (Air Operated): Make: Budenberg; Range: 0.1 to 7 kg/cm2; Accuracy: 0.05% of the range. It is used for calibration of the dial gauges (pressure gauges). Relief Valve Test Rig: Make: Cross-beg or Sorasin & Forris. Air Hydro Pump: Make: SYNCO & MICRO Precision; Range: It should be as required at site. Pressure Gauge Compactor: Make: Budenberg; Range: 5 to 150 kg/cm2. List of Other Misc. Instruments Ammeter Measuring Tapes Temperature Bore Gauges Mercury Recorder Depth Thermometer Thermocouple Micrometer Micrometers Thermometer Dial Callipers Multi-meter (Digital) Dial Gauges Outside Thermometer Dial Micrometer Micrometer (Mercury/Alcohol) Dial Snap Plain Plug Gauges Thickness Gauges Gauges Pressure Recorder (D-Meter) Dial Thickness Push Pull Meter Timers (Analogy & Gauges Slip Gauges Digital) Hardness Tester Snap Gauges Vacuum Pump Impact Tester Steel Rules Vermeer Callipers Inside Temperature Vermeer Height Micrometer Gauges Gauges Measuring Pins Voltmeter
9.9
Visual Inspection
Visual inspection is a common method of quality control, data acquisition, and data analysis. Visual Inspection means inspection of piping and supports using either or all of human senses such as vision, hearing, touches and smell. Visual Inspection typically means inspection using raw human senses and/or any non-specialized inspection equipment. Visual examination is the observation and watching of the portion of piping components, joints, and other piping elements that are or can be exposed to view before, during, and after manufacture, fabrication, assembly, erection, examination and testing. This examination includes verification of code and engineering design documents for requirement of materials, components, dimensions, joint penetration, alignment, welding, bonding, cleanliness, preheating, fit-up, positions and electrodes, condition of root pass, slag removal, proper bolting and projection through the nut, threading or other joining methods, and supports. Inspections requiring Ultrasonic, X-Ray equipment, Infra-red, etc are not typically considered as Visual Inspection as these Inspection methodologies require specialized equipment and training. Each welder or operator work, looking into the completed work, and checking the equipment, electrode being used and type of base metal being welded: Materials: There is a chance of mixing of the carbon steel material with the alloy steel piping material during fabrication, erection and assembly of piping system. The operational conditions of the two materials are different. Hence, it is very important to verify or assess the validity of the material used in the particular system. Now days, it is very easy to examine the type of material used without disturbing the installation of the piping system. Visual inspection of all piping components should be carried out with respect to the outside diameter, pipe ends, out of roundness and wall thickness dents before starting the fabrication and assembly of piping work along with Material Test Certificate Review. Outside Diameter: The outside diameter of the piping components should not be greater or smaller than 0.75% of the diameter of the components up to 20” NB. Pipe Ends: The outside diameter should not be smaller than 0.4 mm up to a length of 4” (100 mm) from the end of pipe up to size 10” NB but should not be larger than the specified outside diameter. The outside diameter should not be smaller than 0.8 mm up to a length of 4” (100 mm) from the end of pipe of size 12” NB and larger but should not be larger than the specified outside diameter. The outside diameter should not be smaller than 0.8 mm up to a length of 4” (100 mm) from the end of pipe up to size 20” NB and larger and should not be larger than 2.4 mm of the specified outside diameter up to a length of 4” (100 mm) from the end of pipe of size 20” NB and larger. Out of Roundness (Oval): The difference between the larger and the smaller dimension of the diameter measured at the right angle at the end should not be more than 5%. Wall Thickness: The wall thickness should not be less than 12.5% and more than 15.0% of pipe wall thickness up to size 18” NB and smaller. The wall thickness should not be less than 10.0% and more than 17.5% of pipe wall thickness up to size 20” NB and larger. Dents: The pipe should not contain any dent greater than 6.35 mm, measured as the gap between the lowest points of the dent and prolongation of the original contour of the pipe. The length of the dent in any direction of the piping component should not exceed one-half of the diameters. All cold-formed dents deeper than 3.18 mm with a sharp bottom gouge should be considered as a non-acceptable dent. Filling and grinding up to the surface finish can rectify the gouge. Weld: Visual inspection of all welds should be carried out with respect to the offsets, height of
outside weld bead, height of inside weld bead, trim of inside weld bead, laminations, spatters, arc burns, burs, high & low Point, surface porosity, under-cut and other kind of surface defects as described below in accordance with the following requirements: Weld Offset: The radial offset (misalignment) of the edge at root of the joint should not be more than 1.6 mm in t he pipe with wall thickness 12.7 mm and less and 3.18 mm in pipe with wall thickness 12.7 mm or larger. Height of outside Weld Bead: The outside weld bead above the prolongation of the original outside surface of the pipe should not be greater than 3.18 in case of pipe thickness 12.7 mm and under and 4.76 mm in case of pipe thickness over 12.7 mm. If the outside bead is greater than as permitted above, should be ground finish to acceptable limit. Height of Inside Weld Bead: The inside weld bead above the prolongation of the original inside surface of the pipe should not be greater than 1.5 mm. Trim of Inside Weld Bead: The depth of groove (protrusion at the root weld) weld bead above the prolongation of the original surface of the pipe, after grinding, should not be greater than 0.10 X t in case of pipe thickness 3.81 mm and under, 0.38 mm in case of pipe thickness 3.84 mm to 7.64 mm and 0.05 X t in case of pipe thickness 7.64 mm and over.. If the protrusion of the bead is greater than as permitted above, it should be ground finish to acceptable limit as given above. Laminations: When the Laminations extend into the face or bevel of the pipe in a transverse direction more than 6.30 mm, are considered as a defect in pipe. The pipe containing such defects should be cut back until all laminations are removed before fit up of the joint. Arc Burns: The localized point of surface melting caused by arcing between electrodes or ground wire and pipe surface are considered as a defect and should be removed and ground finished smoothly into the original contour of the pipe, provided the remaining wall thickness of pipe is within the specified limit. If the remaining wall thickness of pipe is less than the specified limit, the cavity should be repaired b filling the cavity with weld metal to a minimum length of 2” (50.4 mm). The repaired weld should be ground finished smoothly into the original contour of the pipe and the repaired weld should be inspected with magnetic particle method or Dye Penetration test method. If the arc burns are severe and over the pipe surfaces at many places, the portion of the pipe containing the arc burns should be cut off within the limit of requirements of length. Undercuts: The undercuts is the reduction in the thickness of the pipe wall thickness adjacent to the weld, where weld is fused to the surface of the pipe. The undercuts up to the depth of 0.8 mm and length of 150% of the pipe wall thickness and maximum at two places in the total length of 300 mm or the depth of 0.4 mm and of any length are called minor and are acceptable. If the undercuts on the weld of the pipe are longer or deep than the limits specified above, it should be repaired by weld metal filling and smooth grinding.
ACCEPTANCE LIMIT OF WELDING D EFECTS I NSPECTION 1. Internal Misalignment : 1.5 mm or less. 2. Crack or Lack of Fusion: Non-Permitted. 3. Incomplete penetration: Depth should not exceed the lesser of 0.8 mm or 20% of thickness of thinner component joined by Butt Weld. The total length of such defects should not exceed 38 mm in any 150 mm of weld length. 4. Surface Porosity and Slag Inclusion (pipe thickness 4.7 mm or less): Non-permitted
5. Concave Root Surface (Suck up): The thickness of the weld joint (including the reinforcement of the weld) should not reduce less than the thickness of the thinner component welded in case of SingleGroove welding. 6. Weld Ripples & Irregularities: 2.5 mm or less. 7. Lack of Uniformity in Weld Bead Width: 2.5 mm or less. 8. Lack of Uniformity in Weld Leg Length: 2.5 mm or less. 9. Unevenness of Weld Bead: 2.0 mm or less. 10. Weld Undercutting: 0.8 mm or 25% of the thickness of the thinner component welded, whichever is less in case of Single Groove weld. 11. Weld Overlap: 1.5 mm or less. 12. Weld Bead Deflection: 2.5 mm or less. 13. External Weld Reinforcement: External Weld Reinforcement and Internal Weld and Internal Weld Protrusion. Protrusion should be fused with and merged smoothly into the parent surfaces. The height of the lesser projection of external weld reinforcement or internal weld protrusion from the adjacent base material surface should not exceed the following limits: Thinner component’s
Weld Reinforcement or Internal Weld Protrusion 0.4 mm and under 1.6 mm 0.4 mm to 12.7 mm 3.2 mm 12.8 mm to 25.4 mm 4.0 mm Over 25.4 mm 4.8 mm 14. Throat Thickness of Fillet Weld: Throat Thickness of Fillet Weld should be minimum 70% or more of the thickness of thinner component. The weld having any of the above imperfection, which exceeds the specified limit as given above, should be repaired by weld filling, grinding or overlaying etc. 15. Mechanical Completion Watch-Points: After completion of the piping fabrication, assembly and installation, certain checks must be done as per P & ID, ISOs and GA drawings and before preparing for the Leak Test of the piping system as per the following Watch-Points: Installation of the blind Flanges on all vents and drains and other location. Proper diameter, length and material of studs, nuts, gaskets and the flanges at the entire flange joints. Drilling of 3/8” weep holes, if required as per specification. Completion of all utilities hoses stations with proper fittings and material. All valves are easily approachable and operable. All stud bolts and nuts are properly tightened on entire flanges. The compressor suction line is provided with low point drains. All valve traps are installed in correct direction as marked on the trap. All level gauges and level bridles are provided with drains and vents. All drains and vents are provided with blind flanges or caps or plugs. The flare drains are adequately restrained. Permanent Strainers to be installed during pre-commissioning after hydrostatic test and flushing of the line.
The vents have been provided on the line going to the heat exchanger having non-condensable gas. Man-way hinge is provided with suitable length of bolts. All flanges are of proper size, rating, and properly aligned and gap between the flanges is uniform around. All globes and check valves direction correct as per direction indicator. All piping components such as heavy valves, safety valves or control valves are provided with proper supports. The lines are properly and adequately restrained. Proper type of spectacle blinds is installed on the proper side of the valves. All valves are provided with the suitable hand wheels, hand levers or operating gears. All jack bolts are installed. All valves are installed correctly such as globe valve for globe valve and gate valve for gate valve. All tapping of gas, steam, air and vapour lines are taken on the top of the line header. Any additional component installed, though not shown in the drawing. The gland packing installed and bonnet of all valves is tight. The bleed between the two-block valves is provided with plug. All lines connected to compressor suction and discharge has a proper guides, stops, and supports. All highest points and lowest points in the line are provided with suitable vents and drains respectively. Surrounding area is clean. The suction and discharge lines of the pump are provided with suitable drains. All proper supports are installed at all support locations with proper guides. The temporary tacking provided during erection on sliding supports is removed by grinding and ensure it is free to slide. All temporary shims or temporary supports are removed. All anchor supports are welded properly and adequately as per the drawings. All spring supports are in locked position during leak testing and are properly unlocked after the leak test is over. Pipe Trunion are supported properly. The drain valves are minimum 50 mm above the ground finish level. Check all valves for free operation. The shoe support height is sufficient to accommodate the insulation thickness of the line. The steam lines are provided with steam traps at all expansion loops, all swage (reducing) points and all blinds. All threaded plugs are seal welded in high-pressure steam lines. Nitric acid test: In this process, we clean the surface to silver white. Then, a drop of the particular liquid is applied on the surface and watched carefully for the formation of the bubbles due to reaction of the chromium or molybdenum with the liquid. In case of carbon steel, there is no formation of bubble as there is no any chrome or molly present. Chrom-Moly Detection Method: In this method, there is a kit supplied by the vendor. The surface to be detected has to be cleaned to silver white. A drop of the particular liquid is applied on the pipe surface. Then a litmus paper is put on the surface. An electric current is passed through probe on the litmus paper and the metal. The litmus paper picks up the molecules of chromium or molybdenum,
when a drop of another liquid is applied on the litmus paper; it changes its colour to conform the presence of the particular element. Thus we confirm whether it is a carbon steel or alloy steel. All this activities are done in accordance with the procedure of the testing kit vendor. Electronic Metal Detector: Electronic Metal Detector along with the kit is used for detection of the material on the job without destruction of the job. Different kind of material is detected with the kit on the spot.
9.10
Radiographic Inspection (RT)
The Radiographic Testing (RT) is a non-destructive testing (NDT) method of inspecting weld for hidden flaws by using the ability of short wavelength electromagnetic radiation (high energy photons) to penetrate various materials, such as X-Rays and Gamma Rays. Radiography (X-ray) is one of the most important, versatile and widely accepted of all the non-destructive examination methods. The visibility of a flaw depends on the sharpness of its image and its contrast with the background. The Radiographic exposure is acceptable and gives good results when a gauge known as an “Image Quality Indicator” (IQI) is placed on the part so that its image will be produced on the radiograph. IQl used to determine radiographic quality. It is also called “Penetrameter”. A standard hole-type penetrameter is a rectangular piece of metal with three drilled holes of set diameters. The thickness of the piece of metal is a percentage of the thickness of the specimen being radiographed. The diameter of each hole is different and is a given multiple of the penetrameter thickness. Wire-type penetrameter is also widely used,. They consist of several pieces of wire, each of a different diameter. Sensitivity is determined by the smallest diameter of wire that can be clearly seen on the radiograph. A penetrameter is not an indicator or gauge to measure the size of a discontinuity or the minimum detectable flaw size. It is an indicator of the quality of the radiographic technique. Radiographic images are not always easy to interpret.
Figure: Weld Joint being x-rayed
Figure: Plate specimen being xrayed
Film handling marks and streaks, fog and spots caused by developing errors may make it difficult to identify defects. Such film artefacts may mask weld discontinuities. Radiography is the use of X-rays to view a non-uniformly composed material such as the human body. By using the physical properties of the ray an image can be developed which displays areas of different density and composition. The Electromagnetic Spectrum: Either an X-ray machine or strong gamma sources (> 2 Ci), such as Radioactive Source like Iridium-192 (Ir-192), Cobalt-60 (Co-60) or in rare cases Cs-137 is used as a source of photons. Neutron is also used for radiographic testing (RT), which is different than X-ray or Gamma-Ray. Neutrons too penetrate materials. Neutrons can see very different images from X-rays or Gamma-Ray, because Neutrons can pass with ease through lead too and steel but are stopped by plastics, water and oils. X-rays and gamma rays differ only in their source of origin. X-rays are produced by an x-ray generator and gamma rays are the product of radioactive atoms. Both of them are part of the electromagnetic spectrum. They are waveforms like the light rays, microwaves, and radio waves. X-rays and gamma rays cannot be seen, felt, or heard. They possess no charge and no mass and, therefore, are not influenced by electrical and magnetic fields and will generally travel in straight lines. However, they can be diffracted (bent) in a manner similar to light. Both X-rays and gamma rays can be characterized by frequency, wavelength, and velocity. They are described in terms of a stream of photons (mass less particles), each travelling in a wave-like pattern and moving at the
speed of light. Their wavelength is short. As they pass through matter, they are scattered and absorbed and the degree of penetration depends on the kind of matter and the energy of the rays. Equipment and Materials: Radiography can be done with one of the following equipment, X-ray Machine: following portable X-ray machine is available and can be used, ERESCO 200 MF Manufactured by SEIFERT & CO. The rated tube voltage is 200 kV and rated tube current is 5 mA. X-rays occur in the heavy atoms of tungsten. Tungsten is often the material chosen for the target or anode of the x-ray tube. X-ray tubes produce x-ray photons by accelerating a stream of electrons to energies of several hundred kilovolts with velocities of several hundred kilometres per hour and colliding them into a heavy target material. Properties of X-Rays and Gamma Rays: They are not detected by human senses (cannot be seen, heard or felt). They travel in straight lines at the speed of light. Their paths cannot be changed by electrical or magnetic fields. They can be diffracted to a small degree at interfaces between two different materials. They pass through matter until they have a chance encounter with an atomic particle. Their degree of penetration depends on their energy and the matter they are travelling through. They have enough energy to ionize matter and can damage or destroy living cells. Gamma Radiation: Gamma rays are natural radioactivity. Gamma rays are electromagnetic radiation like X-rays. Gamma rays are the most energetic form of electromagnetic radiation, with a very short wavelength of less than one-tenth of a nanometre. Gamma rays are the product of radioactive atoms. Depending upon the ratio of neutrons to protons within its nucleus, an isotope of a particular element may be stable or unstable. When the binding energy is not strong enough to hold the nucleus of an atom together, the atom is said to be unstable. Atoms with unstable nuclei are constantly changing as a result of the imbalance of energy within the nucleus. Over time, the nuclei of unstable isotopes spontaneously disintegrate, or transform, in a process known as radioactive decay. Various types of penetrating radiation may be emitted from the nucleus and/or its surrounding electrons. Nuclides which undergo radioactive decay are called radionuclide. Any material which contains measurable amounts of one or more radionuclide is a radioactive material. The four series represented are Th232, Ir192, Co60, Ga75, and C14. Carbon-14 is not used in radiography. Radio Isotope (Gamma) Sources: Two of the major gamma-ray sources used for industrial radiography is iridium-192 and cobalt-60. These isotopes emit radiation in a few discreet wavelengths. Cobalt-60 will emit a 1.33 and a 1.17 MeV gamma ray, and iridium-192 will emit 0.31, 0.47, and 0.60 MeV gamma rays. In comparison to an X-ray generator, cobalt-60 produces energies comparable to a 1.25 MeV X-ray system and iridium-192 to a 460 keV X-ray system. These high energies make it possible to penetrate thick materials with a relatively short exposure time. Gamma Rays sources are very portable and so are the main reasons that gamma sources are widely used for field radiography. Of course, the disadvantage of a radioactive source is that it can never be turned off and safely managing the source is a constant responsibility. Physical size of isotope materials varies between manufacturers, but generally an isotope material is a pellet that measures 1.5 mm x 1.5 mm. Depending on the level of activity desired, a pellet or pellets are loaded into a stainless steel capsule and sealed by welding. The capsule is attached to short flexible cable called a pigtail. Gamma-ray Source: Iridium 192 radioactive isotope or Cobalt-60 isotope is used for the radiography purpose. The thickness limitation for iridium, Ir-192 is as follow, Material
Minimum Thickness
Steel High Nickel Aluminium
19 mm 16.5 mm 63 mm
The source capsule and the pigtail are housed in a shielding device referred to as a exposure device or camera. Depleted uranium is often used as a shielding material for sources. The exposure device for iridium-192 and cobalt-60 sources will contain 45 pounds and 500 pounds of shielding materials, respectively. Cobalt cameras are often fixed to a trailer and transported to and from inspection sites. When the source is not being used to make an exposure, it is locked inside the exposure device. Gamma radiation sources, most commonly Iridium-192 and Cobalt-60, are used to inspect a variety of materials. The vast majority of radiography concerns the testing and grading of welds on pressurized piping, pressure vessels, high-capacity storage containers, pipelines, and some structural welds. For purposes of inspection of weld metal, there exist several exposure arrangements, such as, (i) Panoramic: Panoramic is one of the four single wall exposure/single wall view (SWE/SWV) arrangements. This exposure is created when the radiographer places the source of radiation at the centre of a sphere, cone, or cylinder like tanks, vessels, and piping. Depending upon client requirements, the radiographer would then place film cassettes on the outside of the surface to be examined. This exposure arrangement is ideal - when properly arranged and exposed, all portions of all exposed film will be of the same approximate density. It also has the advantage of taking less time than other arrangements since the source only penetrate the total wall thickness (WT) once and only travel the radius of the inspection item, not its full diameter. The major disadvantage of the panoramic is that it may be impractical to reach the centre of the item like enclosed pipe or the source may be too weak to perform in this arrangement in large vessels or tanks. (ii) The second SWE/SWV arrangement is an interior placement of the source in an enclosed inspection item without having the source cantered up. The source does not come in direct contact with the item, but is placed a distance away, depending on client requirements. (iii) The third is an exterior placement with similar characteristics. (iv) The fourth is reserved for flat objects, such as plate metal, and is also radiographed without the source coming in direct contact with the item. In each case, the radiographic film is located on the opposite side of the inspection object from the source. In all four cases, only one wall is exposed, and only one wall is viewed on the radiograph. (v) The fifth is the contact shot, which has the source located on the inspection object. This type of radiograph exposes both walls, but only resolves the image on the wall nearest the film. This exposure arrangement takes more time than a panoramic, as the source must penetrate the WT twice and travel the entire outside diameter of the pipe or vessel to reach the film on the opposite side. This is a double wall exposure/single wall view DWE/SWV arrangement. (vi) The sixth is the superimpose arrangement, wherein the source is placed on one side of the object, not in direct contact with it, with the film on the opposite side. This arrangement is usually reserved for very small diameter piping or parts and (vii) the last seventh is DWE/SWV exposure arrangement is the elliptical, in which the source is offset from the plane of the inspection object (usually a weld in pipe) and the elliptical image of the weld furthest from the source is cast onto the film.
Before commencing a radiographic examination, it is always advisable to examine the component with one's own eyes, to eliminate any possible external defects. If the surface of a weld is too irregular, it may be desirable to grind it to obtain a smooth finish, but this is likely to be limited to those cases in which the surface irregularities (which will be visible on the radiograph) may make detecting internal defects difficult. After this visual examination, the operator will have a clear idea of the possibilities of access to the two faces of the weld, which is important both for the setting up of the equipment and for the choice of the most appropriate technique. Radiographic Film: X-ray films for general radiography consist of emulsion-gelatine containing radiation sensitive silver halide crystals, such as silver bromide or silver chloride, and a flexible, transparent, blue-tinted base. The emulsion is different from those used in other types of photography films to account for the distinct characteristics of gamma rays and x-rays, but X-ray films are sensitive to light. Usually, the emulsion is coated on both sides of the base in layers about 0.0005 inches thick. Putting emulsion on both sides of the base doubles the amount of radiation-sensitive silver halide, and thus increases the film speed. The emulsion layers are thin enough so developing, fixing, and drying can be accomplished in a reasonable time. A few of the films used for radiography only have emulsion on one side which produces the greatest detail in the image. When x-rays, gamma rays, or light strike the grains of the sensitive silver halide in the emulsion, some of the Br- ions are liberated and captured by the Ag+ ions. This change is of such a small nature that it cannot be detected by ordinary physical methods and is called a "latent (hidden) image." However, the exposed grains are now more sensitive to the reduction process when exposed to a chemical solution (developer), and the reaction results in the formation of black, metallic silver. It is this silver, suspended in the gelatine on both sides of the base that creates an image. Film Selection: The selection of a film for radio graphing depends on a number of different factors. Listed below are some of the factors that must be considered when selecting a film and developing a radiographic technique. (i) It is Composition, shape, and size of the part being examined and, in some cases, its weight and location. (ii) Type of radiation used, whether x-rays from an x-ray generator or gamma rays from a radioactive source. (iii) Kilovolt available with the x-ray equipment or the intensity of the gamma radiation. And (iv) It is relative importance of high radiographic detail or quick and economical results. Selecting the proper film and developing the optimal radiographic technique usually involves arriving at a balance between a numbers of opposing factors. For example, if high resolution and contrast sensitivity is of overall importance, a slower and finer grained film should be used in place of a faster film. Film Handling: X-ray film should always be handled carefully to avoid physical strains, such as pressure, creasing, buckling or friction. Whenever films are loaded in semi-flexible holders and external clamping devices are used, care should be taken to be sure pressure is uniform. If a film holder bears against a few high spots, such as on an un-ground weld, the pressure may be great enough to produce desensitized areas in the radiograph. This precaution is particularly important when using envelope-packed films. Moisture or contamination with processing chemicals should be avoided and films should be grasped by the edges and allowed to hang free. A supply of clean towels should be kept close at hand as an incentive to dry the hands often and well. Another important precaution is to avoid drawing film rapidly from cartons, exposure holders, or cassettes. Such care will help to eliminate circular or treelike black markings in the radiograph that sometimes result due to static electric discharges. Radiographic Film Contrast: Radiographic contrast describes the differences in photographic density in a radiograph. The contrast between different parts of the image is what forms the image and
the greater the contrast; the more visible features become easy. Radiographic contrast has two main contributors: (i) Subject contrast: Subject contrast is the ratio of radiation intensities transmitted through different areas of the component being evaluated. It is dependent on the absorption differences in the component, the wavelength of the primary radiation, and intensity and distribution of secondary radiation due to scattering. (ii) Detector (Film) Contrast: Film contrast refers to density differences that result due to the type of film used, how it was exposed, and how it was processed. Since there are other detectors besides film, this could be called detector contrast, but the focus here will be on film. Exposing a film to produce higher film densities will generally increase the contrast in the radiograph. Film Exposure Technique: The beam of radiation is directed to the middle of the weld under examination and is normal to the weld surface at that point, except in special techniques where known defects are best revealed by a different alignment of the beam. The length of weld under examination for each exposure shall be such that the thickness of the weld at the diagnostic extremities, measured in the direction of the incident beam, does not exceed the actual thickness at that point by more than 6%. The weld metal is placed between the source of radiation and the detecting device (film) in a tight holder or cassette, and the radiation is allowed to penetrate the part for the required length of time to be adequately recorded. The result is a two-dimensional projection of the part onto the film, producing a latent image of varying densities according to the amount of radiation reaching each area. It is known as a radiograph, as distinct from a photograph produced by light. Because film is cumulative in its response (more exposure absorbs more radiation), relatively weak radiation can be detected by prolonging the exposure film until the film can record an image visible after development. The radiograph is examined as a negative, without printing as a positive as in photography. This is because, in printing, some of the detail is always lost and no useful purpose is served. Before commencing a radiographic examination, it is always advisable to examine the component with one's own eyes, to eliminate any possible external defects. If the surface of a weld is too irregular, it may be desirable to grind it to obtain a smooth finish, but this is likely to be limited to those cases in which the surface irregularities (which will be visible on the radiograph) may make detecting internal defects difficult. Defects such as de-laminations and planar cracks are difficult to detect using radiography, which is why penetrant are often used to enhance the contrast in the detection of such defects. Penetrant used include silver nitrate, zinc iodide, chloroform and diazomethane. Choice of the penetrant is determined by the ease with which it can penetrate the cracks and also with which it can be removed. Diazomethane has the advantages of high opacity, ease of penetration, and ease of removal because it evaporates relatively quickly. Film Length: Kodak Mx or equivalent can be for industrial radiography. The number of Radiography film per one circumferential weld should be as per the following Pipe Nominal Size 2” to 3’ 4” to 6” 8” to 12”
Film Length No. of Radiography Films (mm) 150 300 300
2 3 4
14” to 16” 18” 20” 24” 26” & Above
300 300 300 300 300
5 6 7 8 9 or Actual Number (The film should be overlapped by a minimum of 25 mm at both ends)
Radiographic Safety: Industrial radiographers are in many locations required by governing authorities to use certain types of safety equipment and to work in pairs. Depending on location industrial radiographers may have been required to obtain permits, licences and/or undertake special training. Prior to conducting any testing the nearby area should always first be cleared of all other persons and measures taken to ensure that people do not accidentally enter into an area that may expose them to a large dose of radiation. The safety equipment usually includes four basic items, such as, (i) a radiation survey meter such as a Geiger/Mueller counter, (ii) an alarming dosimeter or rate meter, (iii) a gas-charged dosimeter, and (iv) a film badge or thermo luminescent dosimeter (TLD). (i) The survey meter is used to prevent the radiographer from being overexposed to the radioactive source, as well as for verifying the boundary that radiographers are required to maintain around the exposed source during radiographic operations. (ii) The alarming dosimeter alarms when the radiographer "redlines" or is exposed to too much radiation. It will emit an alarm when the meter measures a radiation level in excess of a preset threshold. This device is intended to prevent the radiographer from inadvertently walking up on an exposed source. (iii) The gas-charged dosimeter measures the total radiation received, but can be reset. It is designed to help the radiographer measure his/her total periodic dose of radiation. It can tell the radiographer at a glance how much radiation to which the device has been exposed since it was last recharged. Radiographers in many states are required to log their radiation exposures and generate an exposure report. (iv) The film badge or TLD is a specialized piece of radiographic film in a rugged container. It measures the radiographer's total exposure over time (usually a month) and is used by regulating authorities to monitor the total exposure of certified radiographers in a certain jurisdiction. At the end of the month, the film badge is turned in and is processed. A report of the radiographer's total dose is generated and is kept on file. When these safety devices are properly calibrated, maintained, and used, it is virtually impossible for a radiographer to be injured by a radioactive overexposure. Sadly, the elimination of just one of these devices can jeopardize the safety of the radiographer and all those who are nearby. A suitable area around the radiation source based on the nature and strength of the source should be cordoned off during field radiography so that radiation levels outside the area do exceed the minimum permissible radiation limit, as per the following table: Strength of source (Curies) 5 Ci 8 Ci 10 Ci
Cordon off distance in meters in full occupancy for a work load of 10 hrs/wk 52 65 74
Personnel qualification: All personnel involved in radiography of weld, interpretation and writing of reports, and in the film processing should be qualified in level II or III in accordance with ASNT Recommended Practice SNT - TC – 1A or equal. Surface preparation: The surface of the butt-welded joint should be finished to remove irregularities on both the inside (where accessible) or outside by any suitable process to such a degree that the resulting radiographic image must not mask or confuse with the image of any discontinuity. The finished surface should have reasonably uniform crowns with the reinforcement not greater than as specified in the code. Intensifying Screens: Lead Foil Screens 0.20 mm in thickness can be used. Fluorescent screens should not be used under any circumstances. Viewing Technique of Radiograph Film: Radiographs are a developed film exposed to x-ray or gamma radiation and are viewed on a light-box. However, it is becoming increasingly common to digitize radiographs and view them on a high resolution monitor. Proper viewing conditions are very important when interpreting a radiograph. The viewing conditions can enhance or degrade the subtle details of radiographs. Figure: Interpretation of “Density” while Viewing Radiographs Ambient light levels should be low. Ambient light levels of less than 2 fc are often recommended, but subdued lighting (rather than total darkness) is preferable in the viewing room. A film having a measured density of 2.0 will allow only 1% of the incident light to pass. A film containing a density of 4.0 will allow only 0.01% of the incident light to pass. With such low levels of light passing through the radiograph, the delivery of a good light source is important. Radiographic film quality and acceptability should first be determined. The correct density on the required film type, correct identification information, proper image quality indicator, sensitivity level, and processing and handling artefacts on the film should be verified. Film Viewer: The illuminator must provide light of an intensity that will illuminate the average density areas of the radiograph without glare essential pentameter hold or designated wire to be visible for specified density range. It must diffuse the light evenly over the viewing area. Identification of Radiograph: a Location Marker identifies the radiographs. Location markers are in the form of letter and number made of lead and placed at space at an intervals corresponding to the number of film required for complete coverage of the weld. They are placed on item to be radiograph. The spacing should not exceed 343 mm. For an example, it is 1, 2, and 3, equally spaced at 120 deg. around the pipe. The datum should be taken at the top dead centre or 0 deg. of the pipe. The location marker should be placed so that they will appear correctly oriented (right side up) on the developed radiograph. The location marker should be placed such that they are in ascending order in a clockwise direction when viewed from the datum point, markers. Each radiograph should be marked sufficiently to uniquely identify it with the weld radiograph. The following should appear on each radiograph, in addition to the location markers and penetrameter, such as, 1) Thickness of the specimen; 2) Job No.; 3) Project Name; 4) Date of radiograph; 5) Joint number; 6) Welder number; 7) Line number; 8) Pipe size; and 9) Repair number, if any.
Dark Room and Processing: The unexposed films should be stored in such a manner that they are protected from effect of light, pressure, excessive heat, excessive humidity, damaging fumes or vapours or penetrating radiation. The film should be used on a “first come” “first out” basis. The film should not be exposed to a light more than safelight conditions as per ANSI PH-2.22, which is used to determine the adequacy of the safelight condition of the darkroom. Quality of the radiographs: All radiographs should be free from mechanical, chemical, or other blemishes such as fogging, processing defects, as streaks, water marks or chemical stains, scratches, finger marks, crimps, dirt, static marks, smudges, tears, or false indications to mask or confuse with the image of discontinuity in the interest of object. Density locations: The transmitted film density through the radiographic image of the body of the appropriate penetrameter or adjacent to the designed wire if a wire penetrameter and the area of interest should be 1.8 minimum for a single film viewing for radiographs made with an x-ray source. It should be 2.0 minimums for radiographs made with a gamma-ray source. There is a tolerance of 0.05 in density allowed for variations between Densitometry readings. Step Wedge Film and Densitometer: The density of step wedge comparison films and Densitometer calibration should be verified by comparison with a calibrated step wedge film traceable to a national standard. The Densitometer shall be calibrated in accordance with paragraph 5 of SE-1079, Calibration of Transmission Densitometer. IQI Image Quality Indicators: The penetrameter should be either the hole-type or the wire type and should be manufactured and identified in accordance with the requirement or the alternate allowed in SE-1025 and SE 747. ASME standard penetrameter should consist of those in Table T-233.1 of ASME Section V for the hole type and Table T233.2 of ASME Section V for wire type. IQI Selection: IQI’s should be selected from either the same alloy material group or grade as identified in SE-1025 or from an alloy material group or grade with less radiation absorption than the material be radiograph. IQI selection should be based on subject material thickness. Table T-276 of ASME Section V, Article 2, should be used to determine which IQI is required. The designated hole with essential holes or designated wire diameter should also be as specified in Table T-276. A smaller hole in a thicker penetrameter or a larger hole in a thinner penetrameter may be substituted for any section thickness listed in Table T-276, provided Equivalent Penetrameter Sensitivity (EPS) is maintained and all other requirements for radiography are met. The thickness on which the penetrameter is based is the nominal single wall thickness plus the estimated weld reinforcement not to exceed the maximum permitted by the referencing code. Backing ring or strips should not be considered as part of the thickness in penetrameter selection. The actual measurement of the weld reinforcement is not required. Placement of IQI, Penetrameter: The penetrameter should be placed, generally, on the source side of the part being examined, on the weld or adjacent to the weld. When the configuration or size prevents placing the penetrameter on the part or weld, it may be placed on a separate block made of the same radio graphically similar material or on the film side in contact with the part being examined. The wire type penetrameter should be placed on the weld so that the length of the wire is perpendicular to the length of the weld. At least one pentameter should be placed on each radiograph. IQI Sensitivity: The radiography should be performed with a sufficient sensitive technique to display the whole penetrameter image and the specified holes, or the designated wire of a wire penetrameter, which are essential indications of the image quality of the radiograph.
Backscatter Radiation: A lead symbol “B” with minimum dimensions of 12 mm in height and 1.5 mm thick lettering should be attached to the back of each film holder during each exposure to determine Backscatter radiation on the exposing film. The lead sheets can be placed behind the film holders to reduce the effect of Backscatter. If a light image off “B” appears on a darker background of the radiograph, protection from Backscatter is insufficient and the radiograph should be unacceptable. A dark image of “B” on a lighter background is acceptable. Examination: A single-wall exposure technique is used for radiography whenever it is possible. In other case a double-wall exposure technique is used. In a single-wall technique, the radiation passes through only one wall of the weld (Material), which is viewed for acceptance on the radiograph. Double-wall exposure technique are of three types, such as, Single-wall Viewing: It is a technique in which the radiation passes through two walls and only one weld (material) on the film sidewall that is viewed for the acceptance on the radiograph. For complete coverage of the circumferential welds (material), minimum three exposures are taken at 120 deg. to each other. Double-wall Viewing: It is a technique in which the radiation passes through two walls and the weld (material) in both walls, which is viewed for the acceptance on the same radiograph. Only one penetrameter is used for double-wall technique. Double-wall technique is used for materials and for welds in a pipe or piping components of size 76 mm or less in nominal outside diameter. Elliptical Technique: It is a technique in which the radiation beam is put in offset from the plane of the weld at an angle sufficient to separate the images of the source side film side portions of the weld so that there is no overlap of the areas to be interpreted. Minimum two exposures are taken at 90 deg. to each other for each joint to ensure complete coverage. Geometric Sharpness: The geometric Sharpness of the radiograph should be determined in accordance with the following formula, Ug = Fd/D Where, Ug = Geometric Sharpness; F = Source size; D = Distance from the source of radiation to the weld or Object; d = Distance from source side of weld to the film. The geometric Sharpness of the radiograph should not exceed the following: Material Thickness 2” and less 2” through 3” 3” through 4” 4” and more
Geometric Sharpness Max. in “in” 0.020” 0.030” 0.040” 0.070”
Weld’s Radiograph Interpretation: Interpretation of weld radiographs takes place in three basic steps: (1) detection, (2) interpretation, and (3) evaluation. All of these steps make use of the Inspector’s visual acuity. Visual acuity is the ability to resolve a spatial pattern in an image. The ability of an individual to detect discontinuities in radiography is also affected by the lighting condition in the place of viewing, and the experience level for recognizing various features in the image. The following are the defects found in weldments and how they appear in a radiograph. Discontinuities (Defects) Types: Discontinuities are interruptions in the typical structure of a material. These interruptions may occur in the base metal, weld material or "heat affected" zones. Discontinuities, which do not meet the requirements of the codes or specifications, are referred to as defects. The General Welding discontinuities present in typical of all types of welding are the
following: (i) Cold Lap: Cold lap is a condition where the weld filler metal does not properly fuse with the base metal or the previous weld pass material (interpass cold lap). The arc does not melt the base metal sufficiently and causes the slightly molten puddle to flow into the base material without bonding.
Figure: Cold Lap (ii) Porosity: Porosity is a series of rounded gas pockets or voids in the weld metal, and is generally cylindrical or elliptical in shape. Porosity is the result of gas entrapment in the solidifying metal. Porosity can take many shapes on a radiograph but often appears as dark round or irregular spots or specks appearing singularly, in clusters, or in rows. Sometimes, porosity is elongated and may appear to have a tail. This is the result of gas attempting to escape while the metal is still in a liquid state and is called wormhole porosity. All porosity is a void in the material and it will have a higher radiographic density than the surrounding area.
. Figure: Porosity (iii) Cluster of Porosity: Cluster of porosity is caused when flux coated electrodes are contaminated with moisture. The moisture turns into a gas when heated and becomes trapped in the weld during the welding process. Cluster of porosity appear just like regular porosity in the radiograph but the indications will be grouped close together.
Figure: Cluster of Porosity (iv) Slag Inclusions: Slag is a non-metallic solid material entrapped in weld metal or between weld
material and base metal. Radiographically, slag may appear in various shapes, from long narrow indications to short wide indications, and in various densities, from grey to very dark. In a radiograph, dark, jagged asymmetrical shapes within the weld or along the weld joint areas are indicative of slag inclusions.
Figure: Figure: Cluster of Porosity (v) Incomplete Penetration (IP) or Lack of Penetration (LOP): Incomplete penetration (IP) or lack of penetration (LOP) is a lack of weld penetration through the thickness of the joint or penetration less than specified. It is located at the centre of a weld and is a wide, linear indication. Incomplete penetration or lack of penetration occurs when the weld metal fails to penetrate the joint. It is one of the most objectionable weld discontinuities. Lack of penetration allows a natural stress riser from which a crack may propagate. The appearance on a radiograph is a dark area with welldefined, straight edges that follows the land or root face down the centre of the weldment.
Figure: Incomplete Penetration (IP) or Lack of Penetration (LOP) (vi) Incomplete Fusion: Incomplete fusion is lack of complete fusion of some portions of the metal in a weld joint with adjacent metal either at base or previously deposited weld metal. Incomplete fusion is a condition where the weld filler metal does not properly fuse with the base metal. On a radiograph, this appears as a long, sharp linear indication, occurring at the centreline of the weld joint or at the fusion line and usually appears as a dark line or lines oriented in the direction of the weld seam along the weld preparation or joining area.
Figure: Incomplete Fusion (vii) Internal Concavity or Suck Back: Internal concavity or suck back is a condition where the
weld metal has contracted as it cools and has been drawn up into the root of the weld. On a radiograph it looks similar to a lack of penetration but the line has irregular edges and it is often quite wide in the centre of the weld image.
Figure: Internal Concavity or Suck Back: (viii) Undercut: Undercut is a joint base metal groove melted at the edge of a weld and left unfilled by weld metal at external surface (External or crown undercut) or at Root(Internal or Root). It is an erosion of the base metal next to the crown or Root of the weld. It represents a stress concentration that often must be corrected. In the radiograph, External or crown undercut appears as a dark irregular line along the outside edge of the weld area and Internal or Root undercut appears as a dark indication at the toe of a weld. The undercut is an erosion of the base metal next to the root or outer surface of the weld. In the radiographic image it appears as a dark irregular line offset from the centreline of the weldment. Undercutting is not as straight edged as LOP because it does not follow a ground edge. Undercut appears as an intermittent or continuous groove in the internal surface of the base metal, backing ring or strip along the edge of the weld root.
Figure: Internal or Root Undercut
Figure: External or Crown Undercut (ix) Offset or Mismatch: Offset or mismatch is terms associated with a condition where two pieces being welded together are not properly aligned. The radiographic image shows a noticeable difference in density between the two pieces. The difference in density is caused by the difference in material thickness. The dark, straight line is caused by the failure of the weld metal to fuse with the
land area.
Figure: Offset or Mismatch (x) Inadequate Weld Reinforcement: Inadequate weld reinforcement is an area of a weld where the thickness of weld metal deposited is less than the thickness of the base material. It is very easy to determine by radiograph if the weld has inadequate reinforcement, because the image density in the area of suspected inadequacy will be higher (darker) than the image density of the surrounding base material.
Figure: Inadequate Weld Reinforcement (xi) Excess weld reinforcement: Excess weld reinforcement is an area of a weld that has weld metal added in excess of that specified by engineering drawings and codes. The appearance on a radiograph is a localized, lighter area in the weld. A visual inspection will easily determine if the weld reinforcement is in excess of that specified by the engineering requirements.
Figure: Excess weld reinforcement (xii) Cracks: Cracks can be detected in a radiograph only when they are propagating in a direction that produces a change in thickness that is parallel to the x-ray beam. Cracks will appear as jagged and often very faint irregular lines. Cracks can sometimes appear as "tails" on inclusions or porosity.
Figure: Cracks (xiii) Tungsten inclusions: Tungsten is a brittle and inherently dense material used in the electrode in tungsten inert gas welding. If improper welding procedures are used, tungsten may be entrapped in the weld metal. Radio graphically, tungsten is denser than aluminium or steel, therefore it shows up as a lighter area with a bright white distinct outline on the radiograph. This is a unique defect to the TIG welding process. These discontinuities occur in most metals welded by the process, including aluminium and stainless steels. The TIG welding produces a clean homogeneous weld. It is easily interpreted in radiograph. Tungsten inclusion is usually denser than base-metal particles. Accept/reject decisions for this defect are generally based on the slag criteria.
Figure: Tungsten inclusions (xiv) Oxide inclusions: Oxidation is the condition of a surface which is heated during welding, resulting in oxide formation on the surface, due to partial or complete lack of purge of the weld atmosphere. The condition is also called sugaring. Oxide inclusions are usually visible on the surface of the welded metal (especially Oxide of aluminium). Oxide inclusions are less dense than the surrounding material and, therefore, appear as dark irregularly shaped discontinuities in the radiograph.
Figure: Oxide inclusions (xv) Whiskers: Whiskers are short lengths of weld electrode wire, visible on the top or bottom surface of the weld or contained within the weld. On a radiograph they appear as light, "wire like" indications. These discontinuities are most commonly found in GMAW welds.
(xvi) Burn-Through: Burn-through: Burn-through is a void or open hole in a backing ring, strip, fused root or adjacent base metal. It results when too much heat causes excessive weld metal to penetrate the weld zone. Often lumps of metal sag through the weld, creating a thick globular condition on the back of the weld. These globs of metal are referred to as icicles. On a radiograph, burn-through appears as dark spots, which are often surrounded by light globular areas (icicles).
Figure: Burn-Through Acceptance Criteria: The acceptance criteria for the evaluation of radiographs should be as per ASME Section VIII, UW-51 and UW-52, ASME B31.3, QW191.2, for welder qualifications and ASME B31.3, Table 341.3.2 for piping items and API 1104 for cross country pipelines and IBR Rules for IBR piping which minimum is as given below: a) 10% of the weld made by each welder or minimum two welds per welder should be examined by radiography for piping over 4” NB pipe. b) 2% of the welds made by each welder or minimum one weld per welder should be examined by radiography for piping 1.5” NB and over but below 4” NB pipe. Acceptance of the Repaired joint: Any defect found in the weld should be repaired and reexamined for acceptance. The number or times of repair is to be restricted as follow: a) Any unacceptable weld joint should be repaired in case of 100% examination. b) In case of Random Examination, Two additional weld joints of the same type, same welder and same welding procedure as a penalty, if possible, have to be marked for repair. These two joints should be acceptable, then no further penalty should be given and the entire three joint are acceptable. c) In case of the two additional weld joints as marked above vide (b), any of the weld reveals any unacceptable defect requiring repair, then further two additional weld joints of the same type, same welder and same welding procedure as a penalty, if possible, have to be marked for repair for each defective joint. If all these joints are acceptable, then all the above five joints are acceptable. d) In case of the above two additional weld joints as marked above vide (c), any of the weld reveals any unacceptable defect requiring repair, then all the above defective joints have to be cut and replaced and re-examined for acceptability. Dissimilar Metals: The radiography of dissimilar materials weld should be done by a more stringent requirement of the dissimilar metals weld together. Wherever, a random radiography is called for, the radiography of the dissimilar metals weld joints should be done first. Reports: The radiographic examination report should be maintained in the format approved. Table: Acceptance Criteria for Weld Imperfections Depth of Incomplete Penetration Cumulative length of Incomplete Penetration Depth of Lack of Fusion
1 mm or 0.2 Tw 38 mm in any weld length of 152 mm 0.2 Tw
Cumulative length of Lack of Fusion Size and distribution of Internal Porosity Slag Inclusion (Individual length)
38 mm in any weld length of 152 mm 1.25D 0.2 Tw/3 2.5 mm or
0.2 Tw
(Individual width) Tw in any weld length of (Cumulative length) 12T Depth of Undercut 1 mm or 0.25 Tw Surface Roughness 500 min. Ra per ASME B46.1 Depth of Root Surface Total joint thickness, Concavity including weld reinforcement Tw Height of Reinforcement or 0.24 Tw Internal Protrusion Crack Not Allowed
9.11
Magnetic Particle Examination
Magnetic particle inspection (MPI) is a non-destructive testing (NDT) process or method of locating and defining discontinuities in magnetic materials such as iron, nickel, cobalt, and some of their alloys. The magnetic particle method is limited to use with ferromagnetic materials and cannot be used with austenitic steels. Magnetic Particle test is done to detect the surface defects such as Porosity, Slag Inclusion, and Crack etc. by creating a magnetic field and by spreading the iron powder on and around the weld. Magnetic Particle test should be carried out on all materials, which are magnetic materials. This test should be carried out within a temperature limit of 150 to 500 C, whenever such tests are specified; the tests shall be carried out on joints chosen by the Owner’s inspector. Magnetic particle testing is not a substitute for radiography or ultrasonic for subsurface evaluations, still it is used with an advantage over their methods in detecting tight cracks and surface discontinuities. Magnetic particle examination of welds and components should be performed in accordance with ASME, Section V-Article 6, 7 and Article 25; ASME Section VIII, Division I-Appendix 6; ASME B31.3; API 650 and API 1104. However, the MPE procedure is described here: Equipment and materials required for MPT are 1) “Portable AC Magnetic Yoke”, 2) Cleaning solvent like ‘Chlorethan, Dub-Check DR-60 Isopropyl l” or equivalent; 3) Ferromagnetic particles- Magnetic Ink for wet non-fluorescent Method- “Magnaflux No. 7 HF Black” and magnetic powder for dry method-“Magnaflux 8A Red or equal” and 4) Colour Contrast- White contrast paint for wet nonfluorescent method- “Magnaflux MX-WCP white contrast” or equal.
Figure: Magnetic particle testing is being used to inspect any defect at plate edges as well as weld. Choice of method: Magnetic powders may be applied dry or wet. The dry powder method is popular for inspecting heavy weldments, while the wet method is often used in inspecting aircraft components. Dry powder is dusted uniformly over the work with a spray gun, dusting bag or atomizer, but the temperature of the surface in this case should not exceed 3150C. The finely divided magnetic particles are coated to increase their mobility and are available in grey, black and red colours to improve visibility. The wet method is more sensitive than the dry method, because it allows the use of finer particles that can detect exceedingly fine defects. If an area of flux leakage is present the particles will be attracted to this area. The particles will build up at the area of leakage and form what is known as an indication. The indication can then be evaluated to determine what it is, what may have caused it, and what action should be taken, if any. Alternating current (AC) is commonly used to detect surface discontinuities. The frequency of the alternating current determines how deep the penetration. Direct current (DC) is used to detect subsurface discontinuities where AC cannot penetrate deep enough to magnetize the part at the depth needed. The amount of magnetic penetration depends on the amount of current through the part. DC is also limited on very large cross-sectional
parts how effective it will magnetize the part. Half wave DC (HWDC or pulsating DC) work similar to full wave DC, but allows for detection of surface breaking indications. HWDC is advantageous for inspection process because it actually helps move the magnetic particles over the test object so that they have the opportunity to come in contact with areas of magnetic flux leakage. The increase in particle mobility is caused by the pulsating current, which vibrates the test piece and particles. Each method of magnetizing has its pros and cons. AC is generally always best for discontinuities open to the surface and some form of DC for subsurface. This requires special equipment that works the opposite of magnetizing equipment. Magnetizing is normally done with high current pulse that very quickly reaches a peak current and instantaneously turns off leaving the part magnetized. To demagnetize a part the current or magnetic field needed, has to be equal or greater than the current or magnetic field used to magnetized the part, the current or magnetic field then is slowly reduced to zero leaving the part demagnetized. Verification of Electromagnetic Strength of Yoke: The magnetizing force of yokes should be checked at least once in a year, or whenever yoke has been damaged. The alternating current electromagnetic power of the yoke should be a lifting of at least 4.5 kg at the maximum pole spacing that will be used. Similarly, the direct current electromagnetic power of yoke should be for lifting of at least 18 kg at the maximum pole spacing that will be used. Qualification of personnel: Personnel performing the MPT test should be to a level Ii, or III qualified by ASNT-TC IA. Magnetic particle powder: It is iron oxide for both dry and wet systems. Wet particles range in size from 0.5 to 10 micrometers for use with water or oil carriers. Particles used in wet systems have pigments applied that fluoresce at 365 nm. Dry particle powders range in size from 5 to 170 micrometers, designed to be seen in white light conditions. Examination procedure: This is the Yoke Technique. The weld and all adjacent area within 25 mm on either side of the weld should be dried, cleaned by any suitable method or by solvents so that it should be free from any slag, dust, oil, grease, scale, spatter etc. White colour contrast paint should be applied on the surface to be tested to provide adequate contrast for wet non-fluorescent method only. The yoke poles are placed on the surface to be examined and the current is switch “ON” after the pole is in contact with the surface of the metal to be tested. The magnetic particle is sprayed by spraying nozzle for wet method and by the mechanical powder blowing or by rubber spray bulb or by manual shaker for dry method over the surface being examined. The Particle Pattern for indications of discontinuities is observed. Then a second examination of the same area is performed by positioning the yoke poles at approximately 900 or perpendicular to the position of yoke poles during the first examination. After each examination is performed, the current should be switched “OFF” before removing the yoke poles from the surface of the metals. While repositioning of the yoke poles for the examination of the next area, the overlapping of the surface is done sufficiently to assure 100% coverage of the area requiring examination. After test is completed, demagnetisation is not required. All MPT test materials or residue should be removed from the surface already tested. Evaluation of defects: The evaluation of defect is done in sufficient light. The intensity of visible light at the surface of the work piece should be from 500 to 1,000 Lux for testing. Acceptance Criteria: The defects should be accepted in accordance with the codes.
9.12
Eddy current
Eddy currents are electric currents, which is induced in conductors when a conductor is exposed to a changing magnetic field. It is induced due to relative motion of the field source and conductor and due to variations of the field with time. This causes a circulating flow of electrons (current), within the body of the conductor. These circulating eddies of current have inductance and thus induce magnetic fields. These fields can cause repulsive, attractive, propulsion and drag effects. The greater currents and hence the greater fields are produced due to stronger magnetic field applied or greater electrical conductivity of the conductor or faster the field changes. Eddy currents generate heat as well as electromagnetic forces. The heat is used for induction heating. The electromagnetic forces are used for levitation, creating movement, or to give a strong braking effect. Self-induced eddy currents are responsible for the skin effect in conductors, which is used for non-destructive testing of materials for geometry features, like micro-cracks. A similar effect is the proximity effect, which is caused by externally-induced eddy currents.
As the circular plate moves down through a small region of constant magnetic field directed into the page, eddy currents are induced in the plate. The direction of those currents is given by Lenz's law, i.e. so that the plate's movement is hindered. When a conductor moves relative to the field generated by a source, electromotive forces (EMFs) can be generated around loops within the conductor. These EMFs acting on the resistivity of the material generate a current around the loop, in accordance with Faraday's law of induction. These currents dissipate energy, and create a magnetic field that tends to oppose changes in the current- they have inductance. Eddy currents are created when a conductor experiences changes in the magnetic field. If either the conductor is moving through a steady magnetic field, or the magnetic field is changing around a stationary conductor, eddy currents will occur in the conductor. Applications: Eddy current techniques are commonly used for the non-destructive examination (NDE) and condition monitoring of a large variety of metallic structures, including heat exchanger tubes, aircraft fuselage, and aircraft structural components. Eddy currents are the root cause of the skin effect in conductors carrying AC current. Similarly, in magnetic materials of finite conductivity eddy currents cause the confinement of the majority of the magnetic fields to only a couple skin depths of the surface of the material. This effect limits the flux linkage in inductors and transformers having magnetic cores.
M AGNETIC FLUX LEAKAGE Magnetic flux leakage (MFL) is a magnetic method of non-destructive testing that is used to detect corrosion and pitting in pipe, steel structures, pipelines and storage tanks. The basic principle is that a powerful magnet is used to magnetize the steel. At areas where there is corrosion or missing metal, the magnetic field "leaks" from the steel. In an MFL tool, a magnetic detector is placed between the poles of the magnet to detect the leakage field. Analysts interpret the chart recording of the leakage
field to identify damaged areas and hopefully to estimate the depth of metal loss. This article currently focuses mainly on the pipeline application of MFL, but links to tank floor examination are provided at the end. The primary purpose of an MFL tool is to detect corrosion in a pipeline. To more accurately predict the dimensions (length, width and depth) of a corrosion feature, extensive testing is performed before the tool enters an operational pipeline. Defects can be simulated using a variety of methods. There are cases where large non-axial oriented cracks have been found in a pipeline that was inspected by a magnetic flux leakage tool. What is not easily identifiable to an MFL tool is the signature that a crack leaves. MFL technology has evolved to a state that makes it an integral part of any cost effective pipeline integrity program. Although high-resolution MFL tools are designed to successfully detect, locate and characterize corrosion, a pipeline operator should not dismiss the ability of an MFL tool to identify and characterize dents, wrinkles, corrosion growth, mechanical damage and even some cracks.
9.13 Dye penetrant Test (DPT / LPT) Surface porosity, slag Inclusion cracks and pinholes are located by liquid penetrant inspection in welds in austenitic steels and nonferrous materials where magnetic particle inspection is useless. Dye Penetration test should be carried out on all kind of materials (both ferrous and non-ferrous) including Austenitic stainless steels and nonmagnetic materials. This test is carried out within a temperature limit of 150 to 500 C. The liquid Penetration examination also termed as Dye Penetration Test. The liquid Penetration examination should be done as per ASME Section V, Article 6 & 24, NonDestructive Examination.
Figure: Dye penetrant Test is being used to detect the defect in a Fillet Weld Test Materials: Two types of penetrating liquids are used, (i) fluorescent and (ii) visible dye. A white developer creates a sharply contrasting background to the vivid dye colour. Dye Penetrant Test (DPT) is low-cost inspection method. Penetrant are typically red in colour, and represent the lowest sensitivity. When selecting a sensitivity level one must consider many factors, including the environment under which the test will be performed, the surface finish of the specimen, and the size of defects sought. Penetrant materials: All materials are selected in accordance with ASME Section V, T-631. Typical penetrant materials to be used for DPT are: Manufacture : MAGNAFLUX or ARDROX Trade name : Spot-check or ARDROX Dye Penetrant : SLK- HF/s or 996 P2 Liquid Developer : SKD-NF/Z.9 or 996.9 D1 Cleaner / Remover : SKC-NF/ZC-7 or 9 PR5 Method : Solvent- Removable colour penetration. Procedure: The surface to be examined and all adjacent area within 25 mm should be cleaned thoroughly by the cleaning agents such as detergent, organic solvent, de-scaling solution, paint remover or Penetrant cleaner. All dirt, scale, weld flux, spatter, paint, grease, oil films, water or other materials should be remove that could obstruct the entrance of the Penetrant into discontinuity. The cleaned surface is dried by forced warm air or with the natural atmosphere air to ensure that no trace of cleaning agent remains on the surface. The surrounding light intensity should be between 500 to 1000 Lux. The temperature of the surface to be examined should be between 160C to 520c. If required, the surface should be heated or cooled to bring the surface temperature as specified above The Penetrant is applied either by spraying or brushing. The penetration time should be minimum 10 minutes or as specified by the manufacture. After 10 minute, the excess Penetrant is removed from the surface by spraying the cleaning agent material on cloth and wiping with cloth. Then spraying the
cleaning agent on cloth and wiping the surface until the trace of the Penetrant is removed. Spraying cleaner directly on the part to remove the excess Penetrant is prohibited. The developer should be applied as soon as possible after the removal of the Penetrant to prevent any bleed out from drying on the surface. The developer is applied in a thin layer, ass a coating, by spraying. The overlapping or running developer is avoided to prevent masking the indications. The developer is allowed to dry for sufficient time. Then the surface is observed to detect the nature of defects, which bleed excessively after 7 to 15 minutes after application of the developer. The main steps of Liquid Penetrant Test are mentioned below: Inspection: The inspector will use visible light with adequate intensity (100 foot-candles or 1100 lux is typical) for visible dye penetrant. Ultraviolet (UV-A) radiation of adequate intensity (1,000 microwatts per centimetre squared is common), along with low ambient light levels (less than 2 footcandles) for fluorescent penetrant examinations. Inspection of the test surface should take place after a 10 minute development time. This time delay allows the blotting action to occur. The inspector may observe the sample for indication formation when using visible dye. It is also good practice to observe indications as they form because the characteristics of the bleed out are a significant part of interpretation characterization of flaws. Post Cleaning: The test surface is often cleaned after inspection and recording of defects, especially if post-inspection coating processes are scheduled.
9.14
Ultrasonic Test (UT)
ASME B31.3; ASTM E164; ASME Section V, Article 5; API 1104, Section 6; and ASNT SNT – TC - 1A codes are followed for Ultrasonic Examination. Ultrasonic Inspection is a method of detecting discontinuities by directing a high-frequency sound beam through the base plate and weld on a predictable path. When the sound beam's path strikes an interruption in the material continuity, some of the sound is reflected back. The sound is collected by the instrument, amplified and displayed as a vertical trace on a video screen.
Figure: Ultrasonic sound is being shown how it detects discontinuities of the weld or parent metal up to full depth. Ultrasonic Testing (UT) launches very short ultrasonic sound pulse-waves with centre frequencies ranging from 0.1-15 MHz and occasionally up to 50 MHz into materials to detect internal flaws or to characterize materials. The sound waves, depending on their frequency can be divided into three categories, such as, Audible Frequency Range. Radio Frequency Range. Ultrasonic Frequency Range. Ultrasonic Sound is used in many industrial uses like tyre moulding, metal mixing, and cleaning, nondestructive testing. (A) Piezoelectric Transducers (Contact UT): This is a method of in-contact UT, where the ultrasonic sound pulse-waves are passed over the object being inspected by contact through Couplant. The transducer is typically separated from the test object by a Couplant (oil or grease) or water (in immersion testing). This is called piezoelectric transducers. In contact UT using piezoelectric transducers, the test surface has to be machined smooth to ensure coupling. The Piezo, Electric Crystals can convert electrical impulses to mechanical vibrations. These vibrations, depending on their frequency can travel through different media. They follow the general rules of sound and light, such as, They travel in a straight line. The angle of incident is equal to the angle of reflection. Their intensity is proportional to the squire of the distance (Inverse Square Law). Angle of reflection when they travel from one medium to another is determined by SNELL’S Law. (B) Electromagnetic acoustic transducer (Non-Contact UT): Electromagnetic acoustic transducer (EMAT) is a transducer for non-contact sound generation and reception using electromagnetic mechanisms. EMAT is an ultrasonic non-destructive testing (NDT) method where couplant is not needed since the sound is directly generated in the material underneath the transducer. EMAT is useful
for the NDT applications of automated inspection, hot and cold environments. EMAT is an ideal transducer to generate Shear Horizontal (SH) Bulk Wave mode, Surface Wave, Lamb Wave and all sorts of other guided wave modes in metallic and/or ferromagnetic materials. As an emerging UT technique, EMAT can be used for Thickness measurement, Flaw detection, and Material Property characterization. EMAT has found its applications recently in many industries such as primary metal manufacturing and processing, automotive, rail road, pipeline, boilers and pressure vessel industries. Type of Piezoelectric Transducers (Contact UT): Depending on the type of transmission, the Ultrasonic Examination is divided into two types as below: Normal Probe Testing (Longitudinal Wave Probe Testing): In Normal Probe Testing method, the ultrasonic beam enters the testing object at 90 deg. Normal probe testing is used for thickness measurement, corrosion survey, testing of castings, testing of plates, machined items etc. In this method, the screen is calibrated to a known range by using a calibration block. For example, if the screen is to be calibrated to 250 mm range using a 100 mm-block machine is to be adjusted to get echoes at 2 and 4 as shown in the sketch-A, below. These echoes are called “back wall echoes”
The travel of sound in test block is shown in sketch-B. When the machine is in this setting, each division corresponds to 50 mm. Let us consider a 100 mm block with a defect is being tested with the same set up. As ultrasonic beam is a cone, part of the cone may be obstructed by the defect and the balance will travel to the side. Thus between each back-wall echoes, multiple defect echoes will appear. By seeing the position of these echoes on the screen, depth of defect can be calculated.
Angular Probe Testing (Shear Waves Probe Testing): In Angular probe Testing method, the ultrasonic beam enters the testing object at different pre-set angles. The angle probes methods are used when ultrasonic beam cannot be transmitted normal to the plane of anticipated surface like in welding. Probes of 450, 600, 700 and 800 are used. It is to be observed that the final angle Ø at which the beam enters the medium, on which all calculations are made, Depends on the followings: Mounting of crystal. Type of acrylic wedge through which it will pass before entry. Curvature of wedge. Curvature of testing surface that decides the beam path distance. This distance changes on the trigonometrically calculations for locating the defects. The trigonometrically relations and the corresponding terms used are as below, S = Skip Distance = 2 times the base of triangle made by the incident beam when travelling from testing surface to opposite side. S = 2 x Tan Ø x T Where, S = Skip Distance; T = Thickness of material under testing; Ø = Angle made by the incident UT beam with the normal at the emission point. W = Beam Path Distance- Actual Distance travelled by the UT Beam inside the material in reaching opposite side. W = t x 1/Cos Ø, Where, 45 deg. =1.44 x T 60 deg. =2.00 x T 70 deg. =2.92 x T 80 deg. =5.75 x T In case of a defect, the beam path to the defect can be found out from the calibrated time base. Direct distance (Base of the triangle) is taken from the centre of the weld. Knowing the angle of the probe and thickness, the depth of defect can be calculated.
The probe beam angles are selected on the basis of weld preparation, thickness and curvature. The beam angles most commonly used are as given below: 6 mm to 15 mm = 80 degree, 15 mm to 35 mm = 70 degree, 35 mm to 60 mm = 60 degree to 45 degree, The speed of ultrasonic waves in steel is 5990 meter per second for normal probes and 3230 meter per second for angular probes. Effect of Probe Frequency: High Frequency produces stray echoes (grass traces). High Frequency on coarse structures like cast iron causes greater attenuation losses. High Frequency is more sensitive to smaller flaws. Higher Frequency gives clear echoes, as the solid angle of the beam cone is lesser. The flaw location in UT testing is basically done by calculating the distance travelled = Speed X Time taken. The ultrasonic Examination of the welded joints is done using a Straight and an Angle beam contact method. Personnel Qualification: Personnel performing the UT testing should be qualified and certified in level II or III in accordance with the requirement of code ASNT, SNT-TC-1A. Surface Preparation: All surfaces of contact of the probe on each side of the weld should be made free from spatters, roughness or irregularities that would interfere with the free movement of the probe. All surface coatings should be removed and sufficiently finished to prevent giving the false indications or interfering with the evaluation of the discontinuities. Equipment and Material: Following Equipment and materials are requiring for UT testing: Probes (Piezo-Electrical Crystal): The probe should be capable of generating frequencies over the range of at least 1 MHz to 5 MHz. This may be either, (1) Straight-Beam Search unit or (2) AngleBeam Search unit. Screen: The UT testing Screen should be suitable to provide linear vertical presentation within ± 5% of the full screen height for at least 80% of the calibrated height. Amplitude Controller: The amplitude controller should be capable to control the amplitude accurate over its useful range to ± 20% of the nominal amplitude ratio, to allow the measurement of indications beyond the linear range of vertical display on the screen. Calibration Blocks: The standard reference blocks are as followings: (a) STB - A1 (II W Type 1 or Type 2), or (b) II W Miniature Block or STB-A3 block, Or, (c) ASME Basic Calibration Block. Materials: Suitable couplants such as glycerine or oil with good wetting characteristics for use on the surface to be examined and for use for calibration purpose. Calibration: Prior to UT testing, the probe is calibrated on IIW calibration. The angle Beam probes are calibrated for (i) sound Entry Point (Index Point), (ii) Sound Path Angle such as 45 deg. or 75-deg. etc., (iii) Sweep Range and (iv) Distant Amplitude Correction (DAC)
Curves. The Straight Beam probes are calibrated for (I) Sweep Range and (ii) Distance Amplitude Correction (DAC) Curves. Distance Amplitude Correction Curves (DAC Curves): The intensity of ultrasonic beam is inversely proportion to the square of the distance travelled. This means that a defect, which is away from the testing side, will give a smaller echo in comparison to an echo of the defect on the testing wall side. Further depending on the internal condition of the testing material, U/T energy may get “Scattered” inside the material These attenuation losses will be more as the distance travelled increases. In order to account for these losses, a Distance Amplitude Correction (DAC) Curve is drawn. From a standard hole of, say, 1.6 mm dia., echoes received at 1/8, 3/8, 5/8, 7/8 and 9/8 with same amplitude are marked on the screen or on additional reticule placed on the screen. The amplitude is adjusted such that first echo at 1/8 will say, 75% of the screen. The amplitude will not be changed for further positions. Five points will be marked and these points will be joined by a curve. This curve will act a reference for acceptance. Diameter of the hole will be decided on the basis of severity of inspection required and thickness. Generally, this is decided as per the code or requirement. Examination Procedure: The angle beam probe is used for the examination of the pipe weld. For butt weld, the examination is done from both sides of the weld axis on the parent metal surface. Method-I: (Reflectors Oriented Parallel to the Weld): The angle beam is directed at approximately at right angles to the weld axis from two directions. The probe is manipulated so that the ultrasonic energy passes through the required volume of weld and adjacent base metal. The scanning should be performed at again setting at least two times the primary reference level. The evaluation is done with respect to the primary reference level. Method-II: (Reflectors Oriented Transverse to the weld): The probe should be directed parallel or angular to the weld axis. The probe is manipulated so that the angle beam passes through the 100% of the weld being inspected. The scanning should be performed at a gain setting at two times the primary reference level, or 20 dB, whichever is greater. Evaluation is performed with respect to the primary reference level. The probe should be rotated at 180 deg. and the examination is repeated. Acceptance: All linear indications that produce a response greater than 20% of the reference level should be investigated to determine the location, shape, extent and type of reflectors and should be accepted based on the following criteria, Linear indications such as shallow crater cracks or star cracks, located at the weld surface, with a length less than 3.96 mm are acceptable. Linear indications, other than cracks, such as open to the surface are unacceptable if they exceed 25.4 mm in total length in a continuous 305 mm length of weld or 8% of the weld length. Linear indications are unacceptable if they exceed 50.8 mm in total length in a continuous length of 305 mm length of weld or 8% of the weld length. The surfaces should be thoroughly cleaned with a suitable method after completion of the U/T. Advantages of U/T: The main advantages of UT are the High penetrating power, which allows the detection of flaws deep in the part; High sensitivity, permitting the detection of extremely small flaws; Greater accuracy than other non-destructive methods in determining the depth of internal flaws; capability of estimating the size, orientation, shape and nature of defects; non-hazardous to operations or to nearby personnel and has no effect on equipment and materials in the vicinity; and capable of portable or highly automated operation. The result of U/T is available immediately in comparison to radiography where exposure, processing, drying and interpretation times are required. In U/T, much
higher thickness can be examined as compared to the radiography where thickness is restricted to less than 76 mm in most cases. The critical defects like cracks and lack of fusion can be examined prominently where as in the radiography it can be missed. The planer defects like Lamination cannot be detected by radiography where as it can be detected by U/T distinctly. The expenses are less in U/T than radiography. Disadvantages of U/T: The main disadvantages of UT are the Manual operation requires careful attention by experienced technicians; Extensive technical knowledge is required for the development of inspection procedures; It is difficult to inspect the Parts that are rough, irregular in shape, very small or thin, or not homogeneous and so has to ground finish; Surface must be prepared by cleaning and removing loose scale, paint, although paint that is properly bonded to a surface need not be removed; Couplant are needed to provide effective transfer of ultrasonic wave energy between transducers and parts being inspected unless a non-contact technique is used (Non-contact techniques include Laser and Electro Magnetic Acoustic Transducers (EMAT); and Inspected items must be water resistant, when using water based couplant that do not contain rust inhibitors. Skill of the personnel is required more than radiography. In U/T, the testing is dependent on the skill of the operator. Reproduction of the test results is often difficult. There is no test result record. In radiography, permanent records are maintained as a proof of the quality of work. In radiography, a defects can be shown and explain to the operator who intern can take corrective methods.
9.15
Hardness Test
During welding, the weld joint becomes harder which is not desired at high temperature as well as in cyclic fluid service condition. So, the hardness of the weld is checked after completion of the weld. Standards: ASTM E10 and ISO 6506-1 codes are used for Indentation hardness test. Hardness is the measure of how resistant a solid matter is to various kinds of permanent shape change when a force is applied. Hardness is dependent on ductility, elastic stiffness; plasticity, strain, strength, toughness, visco-elasticity, and viscosity. There are different measurements of hardness, such as, scratch hardness, indentation hardness, and rebound hardness. Scratch hardness: Scratch hardness is the measure of how resistant a sample is to fracture or plastic (permanent) deformation due to friction from a sharp object. The principle is that an object made of a hard material will scratch an object made of a softer material. The most common test is Mohs scale, which is used in mineralogy. Sclerometer makes this measurement. Indentation hardness: Indentation hardness measures the resistance of material to permanent plastic deformation due to a constant compression load from a sharp object. This is primarily used in engineering and metallurgy fields. The tests work on the basic premise of measuring the critical dimensions of an indentation left by a specifically dimensioned and loaded indenter. Common indentation hardness scales are Rockwell, Vickers, Shore and Brinell. Indentation hardness tests are used to determine the hardness of a material to deformation. Macro indentation (Macro hardness) tests are applied to tests with a larger test load, such as 1 kgf or more. The Micro indentation (Micro hardness) tests are widely employed in the hardness testing of materials with low applied loads. In micro indentation hardness testing, a diamond indenter of specific geometry is impressed into the surface of the test material using a known applied force (commonly called a "load" or "test load") of 1 to 1000 gf. Micro indentation tests typically have forces of 2 N (roughly 200 gf or 0.45 lbf) and produce indentations of about 50 μm. Brinell Hardness Test: The Brinell Hardness scale characterizes the indentation hardness of materials through the scale of penetration of an indenter, spring loaded on an instrument. The typical test uses a 10 millimetres (0.39 in) diameter steel ball as an indenter with a 3,000 kgf (29 kN or 6,600 lbf) force. For softer materials, a smaller force is used; for harder materials, a tungsten carbide ball is substituted for the steel ball.
The indentation is measured and hardness calculated as:
Where, P = applied force (kgf); D = diameter of indenter (mm); d = diameter of indentation (mm). BHN is designated by the most commonly used test standards (ASTM E10-08 and ISO 6506-1:2005) as HBW (H for hardness, B for brinell and W for the material of the indenter, tungsten carbide). HBW is calculated in both standards using the SI units as,
Where: F = applied force (N), D = diameter of indenter (mm), d = diameter of indentation (mm). The hardness is shown as XXX HB YYD^2. The XXX is the force to apply (in kgf) on a material of type YY (5 for aluminium alloys, 10 for copper alloys, 30 for steels). Thus a typical steel hardness could be written: 250 HB 30D^2. It could be a maximum or a minimum. Table: Brinell Hardness Numbers Material Lead
Hardness 5.0 HB (pure lead; alloyed lead typically can range from 5.0 HB to values in excess of 22.0 HB) 15 HB 35 HB 120 HB
Aluminium Copper Mild Steel 18-8 (304) stainless steel 200 HB[4] annealed Hardened tool steel 1500–1900 HB
9.16
Hydrostatic Test
The leakages include puncture, a crack, hole, gash, corrosion hole, pincushion, porosity or other opening. The pressure difference between both sides of the leakage point can affect the movement of material through the leak. Fluids will commonly move from the higher pressure side to the lower pressure side. The larger the pressure difference, there will be the more leakage. A hydrostatic test is a way in which leaks can be found in pressure piping or pipelines or vessels. The test involves placing water in the pipe or vessel at the required pressure to ensure that there is no pressure drop in the piping system under test or there is no leak. It is the most common method employed for leak testing of pipes and vessels. This test helps maintain safety standards and durability of a vessel over time. Hydrotest Test Procedure Approval: A written “Hydrostatic Test Procedure” is specified and utilized to perform a leak test. The procedure should prescribe standards for reporting results and implementing corrective actions, if necessary. With the exclusion of instrumentation, piping systems fabricated or assembled in the field shall be tested irrespective of whether or not they have been pressure tested prior to site welding of fabrication. Vessels and other equipments, to facilitate the testing of piping systems, are excluded from the system with the prior approval of Engineer-inCharge. Pumps, compressors and other rotary equipments shall not be subjected to field test pressure. Lines which are directly open to atmosphere such as vents, drains, safety valves discharge need not be tested. All weld joints shall be visually inspected with full of water in the pipe or wherever possible, such lines shall be tested by continuous flow of fluid to eliminate the possibility of blockade. However, such lines, if provided with block valve, shall be pressure tested up to the first block valve. Hydrotest Test Preparation: Each weld joint shall be cleaned by wire brush to free it from rust and any other foreign matter before pressuring the lines. A blank shall be inserted between the companion flanges where a system is to be isolated at a pair of companion flanges. Minimum thickness of the blank shall be designed in accordance with applicable design code. Open ends of piping system where blanks cannot be used, such as pumps, compressors, turbines or wherever equipment or pipe spools have been recovered or disconnected prior to hydrostatic testing, shall be blinded off by using standard blind flanges of same rating as the piping system being tested. Flushing: Flushing shall be done by fresh potable or drinking water or dry compressed air, wherever water flushing is not desirable, to clean the pipe of all dirt, debris or loose foreign material lying inside the pipe. The required pressure for water flushing shall be minimum the fire hydrant pressure or utility water pressure at 10.5 kg/cm2. For air flushing, the Plant Air line, the piping system, or a compressor should be used at the required pressure, which shall be 50 psi maximum. The pressure shall then be released by quick opening of a valve, already in line or installed temporarily for this purpose. This procedure shall be repeated as many times as required till the inside of the pipe is fully cleaned. In line, the instruments like Control Valves, Orifice Plates, Rota meter, Safety Valves and other instruments like thermo wells which may interfere with flushing, shall not be included in flushing circuit during flushing operation. The screens or meshes from all permanent strainers shall be removed before flushing. Screens or meshes shall be reinstalled after flushing but before testing. During flushing temporary strainers shall be retained. Permanent Strainers shall be reinstalled after flushing but before testing. In case, the equipment such as column, vessel, and exchanger form a part of a piping circuit during flushing, the equipments thus included in the circuit shall be completely drained and dried with
compressed air after flushing is completed. During flushing, water or air shall be drained to the safe place directed by the Engineer-in-Charge. If necessary, proper temporary drainage shall be provided by the contractor. Care shall be taken during flushing so as not to damage or spoil work of other agencies. Precautions also shall be taken to prevent entry of water or foreign matter into equipment, electric motors, instruments etc. The valves, specials, distance pieces, inline instruments and other piping part, which is dropped off before flushing, should be reinstalled. The flanges, disengaged for flushing, shall be envisaged by the contractor and approved by the Engineer-in-Charge. These flanges shall be provided with temporary gaskets at the time of flushing. After flushing is completed and approved, the contractor shall reinstall permanent gaskets between the flange joints of the valve, distance pieces and piping specials. However, flanges at equipment nozzles and other places where isolation during testing has been done, only temporary gaskets shall be provided. Records for flushing, in triplicate, shall be prepared and submitted by the contractor for each piping system for the flushing done in the standard Performa. Pressure gauges used in testing shall be installed as close as possible to the lowest point in the piping system to be tested, to avoid overstressing of any of the lower portion of the system. Two or more pressure gauges shall be installed at locations decided by the Engineer-in-Charge for longer lines and vertical lines. Any of the following alternatives shall be adopted for pressure testing for lines containing check valves: Whenever possible, pressurize up-stream side of valve. Replace the valve by a temporary spool and reinstall the valve after testing. Provide blind on valve flanges, test the upstream and downstream of the line separately, and remove the blind after testing. At these flanges, temporary gaskets shall be provided during testing and shall be replaced by permanent gaskets subsequently Flapper or seat shall be removed during testing (if possible), for check valves in lines 1 1/2” and below, after completion of testing the flapper or seat shall be refitted. Gas lines when hydrostatically tested shall be provided with additional temporary supports during testing. Piping which is spring or counter-weight supported shall be temporarily supported with the help of temporary support, where the weight of the fluid would overload the support. Retaining pins for spring supports shall be removed only after testing is completed and test fluid is completely drained. When testing any piping system, air or steam of approximately 2 kg / cm2g may be used as preliminary test to detect missing gaskets etc. as this avoids the necessity of draining the line to make repairs. However, steam shall not be used for this purpose, if the steam temperature is more than the design temperature of the line. Testing of core pipes, for jacketed pipes, shall be done on individual pieces where the pipe is continuously jacketed, before it is jacketed. The outer jacket shall be tested separately as a system. The core pipe and the jacket shall be tested as separate continuous systems for piping with discontinuous jacketing. Hydrotest Test Media: In general, all pressure tests shall be hydrostatic using iron free water, which is potable, clean and free of silt. Maximum chlorine content in water for hydrostatic testing for SS piping shall be 15-20 ppm. Air shall be used for testing only if water would cause corrosion of the system or overloading of supports etc. in special cases. Where air/water tests are undesirable, substitute fluids such as gas oil, kerosene, methanol etc. shall be used as the testing medium, with due consideration to the hazards involved. These test fluids shall be specified in the line list given to the
contractor. Hydrotest Test Pressure: The hydrostatic or pneumatic test pressure shall be as indicated in the line list or as per the instruction of Engineer-in-Charge. The selection of the piping system for one individual test shall be based on Test pressure required as per line design and Maximum allowable pressure for the material of construction of piping, whichever is higher. Pressure Gauges: All gauges used for field-testing shall have suitable range so that the test pressure of the various systems falls in 40 % to 80% of gauge scale range. Gauge shall be of a good quality and in first class working condition and calibrated within six months period. Prior to the start of any test or periodically, during the field test programmed, all test gauges shall be calibrated using a standard dead weight gauge tester or other suitable approved testing apparatus. Any gauge showing an incorrect zero reading or error of more than + 2 % of full-scale range shall be rejected. The Engineer-in-Charge shall check the accuracy of master pressure gauge used for calibration. Precautions: All expansion joints should be tested without temporary restraint at the lesser of the required test pressure or 1.5 times the design pressure. A metallic bellows expansion joint should not be subjected to any pressure excess of its shop test pressure. The Hydrostatic test pressure of a metallic piping is always done at a pressure equal to 1.5 times the designed pressure or at the specified test pressure as per the design requirements. Some time, the hydrostatic testing of piping system has to be done along with the vessels included in the system. In this case, the piping has to be tested at the lower pressure of the two. Hydrotest Test Witness: Hydrostatic tests are conducted under the supervision of Inspector as per the customer's specifications. The vessel is filled with incompressible liquid, usually water and examined for leaks. The test pressure is always considerably higher than the operating pressure to give a margin for safety and is typically 166.66% or 150% of the designed pressure, depending on the regulations that apply. API RP 1130 and ASME B31.3 section 345 codes are used. Test pressures need not exceed a value that would produce a stress higher than yield stress at test temperature. All vents and other connections used as vents shall be left open while filling the line with test fluid for complete removal of air. Temporary isolating valves shall be provided if valve vents, drains do not exists in the system in all lines for pressurizing and depressurizing the system. Pressure shall be applied only after the system or line is ready and approved by the engineer-in-Charge for testing. Pressure shall be applied by means of a suitable test pump or other pressure source, which shall be isolated from the system as soon as test pressure is reached and stabilized in the system. A pressure gauge shall be provided at the pump discharge for guidance in bringing the system to the required pressure. An authorized person shall attend the pump constantly during the test. The pump shall be isolated from the system whenever the pump is to be left unattended. Test pressure shall be maintained for a sufficient length of time to permit thorough inspection of all joints for leakage or signs of failure. Any joint found leaking during a pressure test should be retested to the specified pressure after repair. Test period shall be maintained for a minimum of three hours. The pump and the piping system to be tested are to be provided with separate pressure indicating test gauges. These are to be checked by the standard test gauge before each pressure test. Care shall be taken to avoid increase in the pressure due to temperature variation during the test. After the hydrostatic test has been completed, pressure shall be released in a manner and at a rate so as not to endanger personnel or damage equipments. All vents and drains shall be opened before the system is to be drained and shall remain open till all draining is complete, so as to prevent formation of vacuum in the system. After draining, lines or systems shall be dried by air. After testing is completed the test blinds shall be removed and equipment or piping isolated during testing shall be
connected using the specified gaskets, bolts and nuts. These connections shall be checked for tightness in subsequent pneumatic tests to be carried out by the contractor for complete loop or circuit including equipments (except rotary equipments). Pressure test shall be considered complete only after approved by the Engineer-in-Charge. Defects, if any, noticed during testing shall be rectified immediately and the contractor at his cost shall do retesting of the system or line. Seats of all valves shall not be subjected to a pressure in excess of the maximum cold working pressure of the valve. Test pressure applied to valves shall not be greater than the manufacturer’s recommendation nor less than that required by the applicable code. Where allowable seat pressure is less than test pressure, test shall be made through an open valve. Instruments in the system to be tested shall be excluded from the test by isolation or removals of the same. Restrictions, which interfere with filling, venting and draining such as Check Valve, Orifice plates etc., shall not be installed unless testing is complete. Control valves shall not be included in the test system. Where bypasses are provided test shall be performed through the bypass or necessary spool shall be used in place of the control valve. Pressure gauges, which are part of the finished system, but cannot withstand test pressure, shall not be installed until the system has been tested. Where piping systems to be tested are directly connected at the battery limits to piping for which the responsibility rests with other agencies, the piping to be tested shall be isolated from such piping by physical disconnection such as valve or blinds. (1) Determination of the test fluid. (2) Comparison of the probable test fluid temperature relative to the brittle fracture toughness of the piping materials (heating the test fluid may be a solution). (3) Depending upon the test fluid, placement of temporary supports where permanent supports were not designed to take the additional weight of the test fluid. (4) Depending upon the test fluid, location of a relief valve to prevent excessive over-pressure from test fluid thermal expansion. No part of the system will exceed 90% of its yield strength. (5) Isolation of restraints on expansion joints. (6) Isolation of vessels, pumps, and other equipment, which may be over stressed at test pressure. (7) Location of the test pump and the need for additional pressure gauges. (8) Accessibility to joints for inspection (some codes require that the weld joints be left exposed until after the test). All joints in the pipe system must be exposed for inspection. (9) Prior to beginning a leak test, the pipeline should be inspected for defects, errors, and omissions. Testing of piping systems is limited by pressure. The pressure used to test a system shall not produce stresses at the test temperature that exceed the yield strength of the pipe material. In addition, if thermal expansion of the test fluid in the system could occur during testing, precautions are taken to avoid extensive stress. Testing of piping systems is also limited by temperature. The ductile-brittle transition temperature should be noted and temperatures outside the design range avoided. Heat treatment of piping systems is performed prior to leak testing. The piping system is returned to its ambient temperature prior to leak testing. In general, piping systems should be re-tested after repairs or additions are made to the system. If a leak is detected during testing and then repaired, the system should be re-tested. If a system passes a leak test, and a component is added to the system, the system should be re-tested to ensure that no leaks are associated with the new component. The documented test records required for each leak test are specified. The records are required to be standardized, completed by qualified, trained test personnel, and retained for a period of at least 5
years. Test records include: - Date of the test; - Personnel performing the test and test location; - Identification of the piping system tested; - Test method, fluid/gas, pressure, and temperature; and - Certified results. Flushing of a piping system prior to leak testing should be performed if there is evidence or suspicion of contaminants, such as dirt or grit, in the pipeline. These contaminants could damage valves, meters, nozzles, jets, ports, or other fittings. The flushing medium shall not react adversely or otherwise contaminate the pipeline, testing fluid, or service fluid. Flushing should be of sufficient time to thoroughly clean contaminants from every part of the pipeline.
9.17
Pneumatic Test
Pneumatic leak tests are not recommended for liquid process piping systems and are only used when the liquid residue left from a hydrostatic test has a hazard potential. The test fluid for a pneumatic leak test is a gas. The gas shall be non-flammable and non-toxic. The hazard of released energy stored in a compressed gas shall be considered when specifying a pneumatic leak test. Safety must be considered when recommending a gas for use in this test. The test temperature is a crucial consideration for the pneumatic leak test. Test temperature shall be considered when selecting the pipe material. Brittle failure is a consideration in extremely low temperatures for some materials. The energy stored in a compressed gas, combined with the possibility of brittle failure, is an essential safety consideration of the pneumatic leak test. A pressure relief device shall be specified when recommending the pneumatic leak test. The pressure relief device allows for the release of pressure in the piping system that exceeds a set maximum pressure. The set pressure for the pressure relief device shall be 110% of the test pressure, or 345 kPa (50 psi) above test pressure, whichever is lower. The test pressure for a pneumatic leak test is 110% of the design pressure. The pressure shall gradually increase to 50% of the test pressure or 170 kPa (25 psig), whichever is lower, at which time the piping system is checked. Any leaks found are then fixed before retesting. The test shall then proceed up to the test pressure before examining for leakage. In general, air is used for the pneumatic leak test. Pneumatic leak test involves the hazard of released energy stored in compressed air. Therefore, sufficient care must be taken to minimize the chance of brittle failure during the pneumatic test. The test temperature is also very important in the case of pneumatic test and must be checked frequently during the pneumatic testing of the system. When testing with air, pressure shall be supplied by means of a compressor. The compressor shall be portable type with a receiver, after cooler and oil separator. Piping to be tested by air shall have joints covered with a soap and water solution so that the joints can be examined for leaks. All other details shall be same as per Hydro testing procedure (specified above) Safety: A pressure relief device should be provided in the piping system, having a set pressure not higher than the pneumatic test pressure plus 50 psi or 10% of the test pressures whichever is less. The safety device must be installed to release the excess pressure increase due to rise in temperature during the test. The test pressure should be 110% of the design pressure or the specified in the design. Procedure: The pressure should be, gradually, increased to 50% of the test pressure or 25 psi, whichever is less. Then a preliminary check should be done for leaks through the joints. The system is left to stabilize. Thereafter, the pressure should gradually increase in steps, in the range of above requirement, till the test pressure is reached. In every step, the piping system is kept in hold for sufficient time to equalize the piping strains and to stabilize the system. Then, the complete piping system is checked with a soap solution for the leaks as specified in BHP code, Section V, Article 10.
9.18
Hydrostatic-Pneumatic Test
Generally, the Hydrostatic- Pneumatic Test is not done in the piping system. This test is sometimes done on the piping in operation. In this case also the pressure is gradually increased in steps in the same manner as in the case of Pneumatic Test to the operating pressure. AT the operating pressure, the checking of all the joints and flange joints are done as per pneumatic test.
9.19
Sensitive Leak Test
A sensitive leak test is required for all Category M fluids (optional for Category D fluids) using the Gas and Bubble Test Method of the ASME Boiler and Pressure Vessel Code, Section V, Article 10, or equivalent. The test pressure for the sensitive leak test is 25% of the design pressure or 105 kPa (15 psig), whichever is lower. Category M fluid service is one in which the potential for personnel exposure is judged to be possible, and in which a single exposure to a small quantity of the fluid (caused by leakage) can produce serious and irreversible personnel health damage upon either contact or breathing. The sensitive leak test is done for large size Gas Line or during operation or commissioning of the piping system with the Gas and Bubble Formation testing, Vacuum Testing, Halogen Diode Detector, Helium Mass Spectrometer Reverse Probe (Snuffer) or Helium Mass Spectrometer Hood Method. The most commonly used method is the Gas and Bubble Formation testing. This test is done as per BHP Code, Section V, Article 10 and the sensitivity of the test should not be less than 10-3 atm. ml/sec under test conditions. The test pressure should not be more than 15 psi or 25% of the design pressure, whichever is less unless, or otherwise it is specified. The areas to be tested should be dry and free from oil, grease, paint and other contaminants, which might mask a leak. All openings should be sealed using plugs, coves, sealing wax, cement, or other suitable materials, which can be readily and completely removed after test is over. The sealing compound should be free from reacting agent with the halogen or testing agent.
9.20
Gas and Bubble Solution Test
The objective of Gas and Bubble Solution Testing is to detect gas escaping from a pressurized component by the application of a solution, which will form bubbles as the gas passes through the defective portion of the weld. The testing gas is generally air unless or otherwise it is specified; however, other gas such as nitrogen or helium may be used. The soap or detergent solution is generally used for leak testing, unless or otherwise it is specified. The pressure is continuously maintained during testing and the soap or detergent solution is applied with help of clean cloth and pouring the solution on the surface to be tested. If there are bubbles continuously forming and bulging out on the surface, it indicates the leak through that location of the weld.
9.21
Vacuum Box Test
The vacuum Box method of testing uses an airtight box of convenient size, such as 30” long and 6” wide, which contain a glass window on its top and the open bottom. The open bottom of the box is placed on the surface with help of suitable sealing gasket and vacuum is developed within the void space of the box. The soap or detergent solution is applied with help of clean cloth and pouring the solution on the surface to be tested and vacuum is continuously maintained during testing. If there are bubbles continuously forming and bulging out on the surface, which can be seen through the glass window, it indicates the leak through that location of the weld.
9.22
Alternative Leak Test
Sometimes, there are few weld joints, which are not subjected to hydrostatic or pneumatic tests during the piping system test. Such joints are examined or tested with Alternative Leak Test method. All circumferential longitudinal or other weld joints should be 100% radiographic and checked for defects as per radiography test requirements. Other welds, where the radiography is not possible, should be examined by Liquid Penetration or Magnetic Particle Methods and fulfils those requirements.
9.23
Repair of Weld
The process of chipping and grinding shall remove defects, ascertained through the inspection methods, which are beyond acceptable limits. When the entire joint is judged and found unacceptable, the welding joint shall be completely cut. The joint edges should be suitably prepared a per required alignment tolerances and welded and shall again be examined by the standard practices adopted earlier. Repairs and / or work of defective welds should be done in time to avoid difficulties in meeting the construction schedules.
9.24
Documentation and Records
Flushing and Test Records in triplicate shall be prepared and submitted by the contractor for each piping system, for the flushing and pressure test done and accepted in the standard Performa. The following records should be completed minimum: Electrode and welding consumable Qualification Record. Tested and approved Records of Consumables for the work. Batch Test Certificates for the electrodes used, obtained from the electrode manufactures. Proposed Heat Treatment Procedure. Heat Treatment Charts. Weld joint hardness test results. Welding Procedure Specifications as per Exhibit-above, immediately after receipt of the order. Welding Procedure Qualification records as per Exhibit-above. Welder Performance Qualification records as per Exhibit-above, immediately after conducting Welder qualification. Qualification Tests. Radiography Procedure and other NDT procedures. Radiographic Test Report along with Radiographs and other NDT reports. Piping sketch (Isometric) giving all the details regarding the Piping Specifications, Welded Joints, Joints Radiographic, Magnetic Particle Tested, Ultrasonic Tested, Penetration Tested, Joints Heat Treated, WPS-used, and Welders Identification Number.
10 Piping Heat Tracing 10.1
General
Heat Tracing is a procedure of heating a process liquid line with the help of (i ) hot steam passing through ½ “ to ¾ “ diameter line mounted all around the main process liquid line or (ii) heating with Electrical Induction Coil wrapped all-round the line. The main purpose of the Heat Tracing is to heat and prevent the fluid passing through the process line from freezing. It also keeps the temperature of the fluid high enough for free flow of the fluid and maintains proper viscosity required for the smooth operation of the pump busy in pumping the liquid. Heat tracing may also be accomplished through the use of fluids such as steam, organic/synthetic liquids, and glycol mixtures, or through electrical systems such as self regulating parallel resistance cable, zone parallel resistance cable, continuouswattage cables and other methods. For the purposes of process piping, heat tracing is the continuous or intermittent application of heat to the piping system, including pipe and associated equipment, to
replace heat loss. As with insulation, heat tracing is used when the process cannot tolerate potential heat loss from the piping or when freezing potential exists.
10.2
Steam Tracing Applications
Heat Tracing System Selection: The selection criteria for determining the most suitable heat tracing methods include: cost, availability of utilities such as steam or electricity, amount of heat to be provided, area hazardous classification as defined by the National Electric Code (NFPA 70), temperature control requirements and consequence of failure. Economics generally favour electrical heat tracing systems when the piping is less than 300 mm (12 in) in diameter and the temperature to be maintained is 120 0C or lower. The steam tracing is most appropriate and being commonly used. Typical inputs are piping size and geometry; ambient, process and desired maintenance temperature; control requirements; labour costs and utility rates. Outputs are typically worst-case heat loss; a bill of materials for the heat tracing system; and capital, installation and operating costs. Steam Tracing: The supply of the steam, for steam tracing purpose is taken from the permanent, undisrupted, independent and continuous supply process steam line, exhaust/ bleeds steam line so that the tracing line should always get the steam, even the other unit or steam lines are under shut down and under maintenance. The main header line supplying steam to the tracer lines are laid down up to the nearest point of the Manifold of the tracing lines. The material of the steam tracing line is API 5L grade B. The steam pressure available at the manifold should be between minimum 1.5 to maximum 3.5 kg/cm2g and the temperature should be minimum the steam saturation temperature of a given temperature. The steam tracing lines are not covered by the IBR; because of its operating the pressure. Hence all other piping Standards and Codes of Refinery piping are applicable. The Steam tracing systems Manifolds include steam distribution and condensate collection. Steam tracing systems bring together all the necessary components like steam traps, manifolds and valves. This costs less and has a compact, easily accessible, centrally located assembly. This is especially important in tracer applications, where steam lines are used to "trace" a pipe to keep the fluid inside at a uniform temperature. The Steam Trapping and Tracing Equipment category consists of three groups of products, such as, (i) Steam Distribution Manifolds (ii) automatic differential condensate controllers (DC) and (iii) steam traps. The process lines to be steam traced are given in the Line schedule. The drawing of steam tracing lines is prepared in accordance with the standards and Line schedules with the following limitations: The steam tracing lines mainly consists of the steam supply main line, sub-line, manifolds, condensate headers, condensate recovery manifolds, and steam traps. The Isometric drawings of the steam supply line and the condensate line return manifolds should be separately indicating the size, number of various supplies and the return leads to and from the designated steam traced lines. One single block valve must be provided at the manifold to take care of the entire connected lines to the manifold. The manifold should be located very near to the steam tracing lines to minimize the length of the supply leads to the tracing lines. The manifold size should be 3” NB. The size of the tracing line should be ½ “ and the numbers of the tracing lines per process line should be as given below:
main line
Size of Number of Tracing Position of tracer process lines line
Up to 4” NB 1 Process Line
Top of Process Line
6” to 16” NB 2 Line 18” and larger Line 3
Top of Process Line 120 apart,
degree
The length of the tracing lines should be as specified below: Open system tracing line: 38 meters maximum length. Closed system tracing line: 24 meters maximum length. The tracer lines should run along with the main process line sticking to it or tied with it with the help of 14 to 16 SWG Soft Annealed Galvanized Wire at a spacing of 0.9 to 1.1 meter. Each tracing line should be connected to one supply lead line and it should be drained through separate Steam Trap connected to each tracing lines. The tracing line should be started from the highest point level in the system and should be routed continuously in a slope towards the steam trap, i.e. towards the condensate drain point. In general, no pocket is allowed in normal case. However, the maximum of 3.0 meter pocket can be allowed with a differential steam pressure of 3.5 kg/ cm2 under vertical plane. The Tracing line pocket is defined as the depth of the vertical travel or rises in the direction of the flow from the low point, i.e. Steam Trap, to the high point of the tracing line. The total depth of the pocket is the sum of all the pockets in the tracing line, which should not exceed the above limit of the maximum of 3.0 meter. The low point in the tracing line should not be provided with any drain as in the case of normal piping low point drain. More than 12 tracing lines should not be connected to a single supply or Condensate collection manifold. There is no need of providing the expansion loop in the tracing line. However, the tracer line should be anchored at the middle of the length of the line and both ends should be provided with sufficient space to compensate the expansion in the tracing line, if required. Each tracing line should be provided with a Steam trap separately. If there are more than one tracing lines are connected to a single condensate collection header, each tracing line should be provided with the check valve. However, there is no need of providing the check valve, if the tracing line is going to discharge the condensate in open OWS drain system. The size of the condensate manifold should be 3” NB. The location of the condensate collection manifold should be at the lowest point or lowest elevation to allow the gravity flow of the condensate from all connected tracing lines to the manifold. (i) Steam Distribution Manifolds: The Steam Distribution Manifold places all steam supply valves in one assembly. Standardizing components and centralizing their location simplify installation, cutting costs from the beginning. Routine maintenance is faster, and you get the peace of mind of a three-year guarantee. It reduces design specification costs, lowers installation costs due to prefabrication, reduces shipping and field handling costs, lowers long-term maintenance and operating costs, has design flexibility, dimensional consistency, and space savings. The Steam Distribution and Condensate Collection Manifolds simplify the tracing applications by bringing all the components like steam traps, steam tracing manifolds and valves together to reduce installation costs and provide a compact, easily accessible assembly that’s centrally located. All of the manifolds use the piston valve because of its excellent performance in steam tracing systems. With piston valve in the system ensures that the leakage to atmosphere is extremely rare, even without any
maintenance. The elastic contact between piston and valve sealing rings provides perfect tightness, both in-line and to atmosphere. The piston valve is a seat less valve that includes two graphite and stainless steel valve sealing rings that seal the stem and function as a seat. This combination provides long-term protection against leaks to the atmosphere and downstream piping. (ii) Automatic differential condensate controllers: Automatic differential condensate controllers are designed for applications where condensate must be lifted from a drain point or in gravity drainage applications where increased velocity will aid drainage. (iii) Steam traps: The steam traps get condensate, air and CO2 out of the steam-tracing system as quickly as they accumulate. Steam traps are key components in any steam- tracing system and have the advantages, such as, minimal steam loss, long life and dependable service, corrosion resistance, air venting, CO2 venting, operation against back pressure and freedom from dirt problems.
Steam Distribution Steam traps Manifolds
Float Steam Traps
Steam Traps minimizes the operational cost for energy and more attention to the environment. An efficient steam trap wastes less energy and hence burns less fuel and reduces emissions. The results are energy savings and a cleaner, healthier environment. The Modulating pressures mean widely varying loads, thermal cycling and high air and non-condensable gas loads. Trap failures on modulating pressure may lead to water hammer, corrosion and even damage to heat exchangers. Material: It is high quality ASTM A48 Class 30 cast iron or ASTM A216 WCB cast steel-normally found in pressure vessels rated to 250 psi (17 bar) or 465 psi (32 bar). Internal mechanisms are made from stainless steel and are heavily reinforced. There are no brass cotter pins in it. Valves and seats are stainless steel, hardened, ground and lapped to withstand the erosive forces of flashing condensate. (a) Float & Thermostatic Steam Traps: Float and thermostatic traps are mechanical units that operate on both density and temperature principles. The float valve operates on the density principle. A level connects the ball float to the valve and seat. Once condensate reaches a certain level in the trap, the float rises, opening the orifice and draining condensate. A water seal formed by the condensate prevents live steam loss. Since the discharge valve is under water, it is not capable of venting air and non-condensable. When the accumulation of air and con-condensable gases causes a significant temperature drop, a thermostatic air vent in the top of the trap discharges them. The thermostatic vent opens at a temperature a few degrees below saturation, so it's able to handle a large volume of air-through an entirely separate orifice-but at a slightly reduced temperature. (b) Disc Steam Traps: The Controlled Disc (CD) Steam Trap is a time-delayed device that operates on the velocity principle. It contains only one moving part, the disc itself. Because it is very light in weight and compact, the CD trap meets the needs of many applications where space is limited. Disc trap is simple and small size. It offers advantages such as resistance to hydraulic shock, the complete discharge of all condensate when open and intermittent operation for a steady purging action.
Operation of controlled disc traps depends on the changes in pressures in the chamber where the disc operates. The CD trap will be open as long as cold condensate is flowing. As soon as steam or flash steam reaches the inlet orifice, the velocity of flow increases, which pulls the disc toward the seat. Increasing pressure in the control chambers snaps the disc closed. The subsequent pressure reduction is necessary for the trap to open. The heating chamber in the cap and a finite machine bleed groove in the disc control the pressure reduction. Once the system is up to temperature, the bleed groove controls the trap cycle rate. (c) Unique heating chamber: The unique heating chamber in Disc Trap surrounds the disc body and control chamber. A controlled bleed from the chamber to the tap outlet controls the cycle rate. That means that the trap design, which is not ambient conditions, controls the cycle rate. Without this controlling feature, rain, snow and cold ambient conditions would upset the cycle rate of the trap. (d) Inverted Bucket Steam Traps: Inverted Bucket Steam Traps is Energy efficient. The inverted bucket is the most reliable steam trap operating principle known. The simple design is a unique leverage system that multiplies the force provided by the bucket to open the valve against pressure. Since the bucket is open at the bottom, it resists damage from water hammer, and wear points are heavily reinforced for long life. The inverted bucket has only two moving parts, such as, the valve lever assembly and the bucket. That means no fixed points, no complicated linkage. Nothing to stick, bind or clog. The inverted bucket steam traps open and close based on the difference in density between condensate and steam on the inverted bucket principle. They open and close gently, minimizing the wear. This simple fact means that inverted buckets are subject to less wear than some other types of traps. In fact, the inverted bucket trap wears actually improves its tight seal. The valve and seat of the trap provide essentially line contact-resulting in a tight seal because the entire closing force is concentrated on one narrow seating ring. An inverted bucket steam trap continues to operate efficiently with use. Gradual wear slightly increases the diameter of the seat and alters the shape and diameter of the valve. But, as this occurs, a tight seal is still preserved-the ball merely seats itself more deeply. The stainless steel valve and seat of the inverted bucket steam trap are individually ground and lapped together in matched sets.
Inverted Bucket Steam Traps
Thermostatic Traps
Steam
All other working parts are wear and corrosion resistant stainless steel. The inverted bucket provides continuous automatic air and CO2 venting with no cooling lag or threat of air binding. The inverted bucket has excellent performance against back pressure. It has no adverse effect on inverted bucket operation other than to reduce its capacity by the low differential. The bucket simply requires less force to pull the valve open and cycle the trap. The inverted bucket is always vertical and so is virtually free of dirt problems. The valve and seat are at the top of the trap, far away from the larger particles of dirt, which fall to the bottom. Here, the up and down action of the bucket pulverizes them. Since the valve of an inverted bucket is either fully closed or open, dirt particles pass freely. And the swift flow of condensate from under the bucket's edge creates a unique self-scrubbing action that sweeps dirt out of the trap. (e) Thermostatic Steam Traps: Thermostatic Steam Traps are available with balanced pressure bellows or wafer-type elements and are constructed in a variety of materials, including stainless steel, carbon steel and bronze. These traps are used on applications with very light condensate loads. Thermostatic steam traps operate on steam’s temperature difference from cooled condensate and air. Steam increases the pressure inside the thermostatic element, causing the trap to close. As condensate and non-condensable gases back up in the cooling leg, the temperature begins to drop and the thermostatic element contracts and opens the valve. The amount of condensate backed up ahead of the trap depends on the load conditions, steam pressure and size of the piping. It is important to note that an accumulation of non-condensable gases can occur behind the condensate backup. Thermostatic traps can also be used for venting air from a steam system. When air collects, the temperature drops and the thermostatic air vent automatically discharges the air at slightly below steam temperature throughout the entire operating pressure range. Hose Stations:
Hose Stations & Wash down Equipment: Hose Stations & Wash Down Equipments have super safe steam & water Hose Stations. The Hose Stations will not pass live steam in the event of a significant cold water pressure reduction or a complete failure of the cold water supply or mechanical failure of its primary operating component. Hose Stations are designed to improve efficiency and reduce risk when mixing steam and water for wash down. When the process demands high wash down temperatures, adjusting the mix of steam and water becomes much easier and safe. With the older style of Hose Stations, dual globe valve Mixing “Y,” it was introducing too much steam, which was providing dangerous consequences for working personnel. Hose Stations are available in bronze and Type 304 stainless steel. The Hot & Cold Water Hose Stations are supplied with an integral Rada 320 Thermostatic Mixing Valve, which full range temperature control from full cold to a field adjustable maximum temperature limit stop in a single
handle rotation and a single temperature lock out, which will hold outlet temperatures +/- 2°F (1°C) in the event of inlet pressure and/or temperature change. Thermal shutdown capability to protect the operator in the event of an inlet supply failure. It is available in bronze or with a heavy duty industrial nickel plate finish. The Single Temperature Hose Stations are supplied with a heavy duty wash down hose and a self closing industrial quality spray nozzle. They are ideal for installation in hot water systems which do not require a secondary point of use water temperature adjustment. Wash down Accessories: There is full range of accessory items, such as, Detergent-injection systems, Wash down Hose, Hose reels/racks, Spray nozzles and Flow indicators along with Liquid Drainers like Compressed air drains, Condensate drainers, Air traps, Water traps, Dump valves, Float traps and Compressed air traps all assembled in a automatic drainage system. It is possible to discharge liquid manually through a valve that has been cracked open. However, an open drain also continuously wastes air or gas. Periodically opening a valve by hand and leaving it until it blows freely will also drain a system. Frequently, however, an operator will delay or forget to close a valve, thereby wasting precious air or gas. Liquid drainers installed at appropriate points will remove liquid continuously and automatically without wasting air or gas. In addition to drainage of the system, liquid drainers should provide: Trouble-free operation with minimal need for adjustment or maintenance, Reliable operation even in the presence of dirt, grit and oil, A long operating life, Minimal air loss and Ease of repair. Condensate Recovery Equipment: Condensate recovery allows reusing all of the valuable Btu within the steam system. Depending on the pressure, condensate leaving a trap contains approximately 20% of the heat energy transferred at the boiler in the form of sensible heat. Condensate recovery systems help to reduce three tangible costs of producing steam: Fuel/energy costs, Boiler water makeup and sewage treatment, and Boiler water chemical treatment. The workhorses in any condensate recovery system are condensate pumps. Their job is to move condensate or other liquids from low points, low pressures or vacuum spaces to an area of higher elevation or pressure. Single pump capacities range from 158 kg/hr to 33112 kg/hr, depending on application conditions.
10.3
Inspection and Testing:
The inspection and Testing of the tracing lines should be exactly in the same way as in case of the steam piping.
11 Lined Piping 11.1
General
When properly utilized, a lined piping system is an effective means by which to protect metallic piping from internal corrosion while maintaining system strength and external impact resistance. Cathode protection is still required for buried applications to address external corrosion. Manufacturing standard options for the outer piping material are usually Schedule 40 or 80-carbon steel. Lined piping systems are not double containment piping systems. a. Design Parameters: Design factors that must be taken into account for the engineering of lined piping systems include: pressure, temperature and flow considerations; liner selection factors of permeation, absorption, and stress cracking; and heat tracing, venting and other installation requirements. b. Operating Pressures and Temperatures: The requirements for addressing pressure and temperature conditions for lined piping systems are summarized in the following paragraphs. Lined piping systems are used primarily for handling corrosive fluids in applications where the operating pressures and temperatures require the mechanical strength of metallic pipe. Therefore, the determination of maximum steady state design pressure is based on the same procedure and requirements as metallic pipe shell, and the design temperature is based on similar procedures and requirements as thermoplastic pipe. Following Table lists recommended temperature limits of thermoplastic used as liners. The temperatures limits are based on material tests and do not necessarily reflect evidence of successful use as piping component linings in specific fluid serviced at the temperatures listed. The manufacturer is consulted for specific application limitations. c. Liner Selection: Liner selection for piping systems must consider the materials being carried, the operating conditions, and external situations. As discussed in Chapter 3-design, metallic material compatibility should consider the type and concentration of chemicals in the liquid, liquid temperature and total stress of the piping system. An engineer experienced in corrosion or similar applications should make the selection of materials of construction. Thermoplastic materials do not display corrosion rates and are, therefore, either completely resistant to a chemical or will rapidly deteriorate. Plastic lined piping system material failure occurs primarily by the following mechanisms: Absorption, Permeation, Environmental-stress cracking, and Combinations of the above mechanisms.
Permeation of chemicals may not affect the liner but may cause corrosion of the outer metallic piping. The main design factors that affect the rate of permeation include absorption, temperature, pressure, concentration, and liner density and thickness. As temperature, pressure, and concentration of the chemical in the liquid increase, the rate of permeation is likely to increase. On the other hand, as liner material density and thickness increase, permeation rates tend to decrease. Liners should not be affected by erosion with liquid velocities of less than or equal to 3.66 m/s (12 ft/s) when abrasives are not present. If slurries are to be handled, lined piping is best used with a 50% or greater solids content and liquid velocities in the range of 0.61 to 1.22 m/s (2 to 4 ft/s). Particle size also has an effect on erosion. Significant erosion occurs at >100 mesh; some erosion occurs at >250 but <100 mesh; and little erosion occurs at <250 mesh. Recommended liners for slurry applications are PVDF and PTFE, and soft rubber; by comparison, in a corrosive slurry application, PP erodes 2 times as fast and carbon steel erodes 6.5 times as fast. Table: Thermoplastic Liner Temperature Limits for Continuous Duty MATERI ALS
Recommended Temperature Limits Minimum Maximum 0 0 0 0 F C F C ECTFE -325 -198 340 171 ETFE -325 -198 300 149 FEP -325 -198 400 204 PFA -325 -198 500 260 PP 0 -18 225 107 PTFE -325 -198 500 260 PVDC 0 -18 175 79 PFDF 0 -18 275 135 Note: Temperature compatibility should be confirmed with manufacturers before use is specified. Source: ASME B31.3, d. Joining: Two available methods for joining lined pipe are flanged joints and mechanical couplings. Thermoplastic spacers are used for making connections between lined steel pipe and other types of pipe and equipment. The spacer provides a positive seal. The bore of the spacer is the same as the internal diameter (D) of the lined pipe. Often, a gasket is added between the spacer and a dissimilar material to assist in providing a good seal and to protect the spacer. When connecting lined pipe to an unlined flat face flange, a 12.7 mm (½ in) thick plastic spacer of the same material as the pipe line is used. A gasket and a spacer will connect to an unlined raised face flange. Both a gasket and a spacer are recommended to connect to glass and lined equipment nozzles. Install a 12.7 mm (½ in) thick spacer between lined pipe or fittings and other plastic hand lined components, particularly valves, if the diameters of the raised plastic faces are different. For small angle direction changes, tapered face spacers may be used. It is not recommended to exceed a five-degree directional change using a tapered face spacer. For directional changes greater than five degrees, precision-bent fabricated pipe sections are available from lined pipe manufacturers.
Gaskets are not necessary to attain a good seal between sections of thermoplastic lined pipe, if recommended fabrication and installation practices are followed. Often, leaks result from using insufficient torque when trying to seal a joint. The addition of a gasket provides a softer material, which seals under the lesser stress developed by low torque. When gaskets or any dissimilar materials are used in the pipe joint, the lowest recommended torque for the materials in the joint is always used. Gaskets are put in when previously used lined pipe is reinstalled following maintenance. Gaskets are also used between plastic spacers and non-plastic-lined pipe, valves, or fittings. The recommended bolt torque values for thermoplastic lined piping systems are shown on Tables given below. Excessive torque causes damage to the plastic sealing surfaces. When bolting together dissimilar materials, the lowest recommended torque of the components in the joint is used. Bolting torque is rechecked approximately 24 hours after the initial installation or after the first thermal cycle. This is required to reseat the plastic and allow for relaxation of the bolts. Bolting is performed only on the system in the ambient, cooled state, and never while the process is at elevated temperature or excessive force could result upon cooling. e. Thermal Expansion: Thermal expansion design for lined piping systems can be handled in a similar manner as metallic piping. Expansion joints have been used to compensate for thermal expansion. However, expansion joints are usually considered the weakest component in a piping system and are usually eliminated through good engineering practices. Due to the bonding between the liner and the metallic pipe casing, pre-manufactured sections of pipe designed to allow for changes in movement of the piping system are available from manufacturers. On long straight pipe runs, lined pipe is treated similarly to carbon steel piping. Changes in direction in pipe runs are introduced wherever possible to allow thermal expansion. A common problem is the installation of lined piping between a pump and another piece of equipment. On new installations, equipment can be laid out such that there are no direct piping runs. Where a constricted layout is required or a piping loop would not be practical, the solution is to allow the pump to "float”. The pump- motor base assemblies are mounted on a platform with legs. These bases are available from several manufacturers or can be constructed. These bases allow movement in order to relieve the stresses in the piping system. f. Heat Tracing and Insulation: Heat tracing, insulation, and cladding can be installed in the same way as discussed above on lined piping systems when required. The key for the design is to not exceed the maximum allowable temperature of the lining. Manufacturer’s recommendations on electrical heat tracing design should be followed to avoid localized hot spots. Steam heat tracing should not be used with most plastic lined piping systems due to the high temperature potential. Venting is required on many lined piping systems to allow for permeating vapour release. If insulation or cladding is to be mounted on the piping system, vent extenders should be specified to extend past the potential blockage. g. Piping Support and Burial: Design of support systems for lined piping systems follows the same guidelines as for the outer piping material. Spans for systems consisting of the material used in the outer pipe may be used. Supports should permit the pipe to move freely with thermal expansion and contraction. The design requirements for buried lined piping systems are the same as those for the outer piping material. That is, a buried plastic lined carbon steel pipe should be treated the same way
as a carbon steel pipe without a liner.
11.2 Plastic Lined Piping Systems Thermoplastic lined piping systems are commonly used and widely available commercially under a variety of trade names. Following Tables presents a summary of some of the material properties for plastic liners, and some of the liner thickness used for the protection of oil production equipment when applied as a liquid coating. Standard liner thickness is 3.3 to 8.6 mm (0.130 to 0.340 inches). a. Common Plastic Liners: Most thermoplastics can be used as liner material. However, the more common and commercially available plastic liners include polyvinylidene chloride, perfluoroalkoxyl, polypropylene, polytetrafluoroethylene, and polyvinylidene fluoride. Polytetrafluoroethylene (PTFE) is a fully fluorinated polymer. Although PTFE is chemically inert to most materials, some chemicals will permeate through the liner. Therefore, venting of the joint area between the liner and outer casing is required. PTFE materials are produced in accordance with ASTM D 1457 with material parameters specified by the designation of type (I through VIII) and class. The manufacture of PTFE lined pipe and materials are in accordance with ASTM F 423. Polyvinylidene fluoride (PVDF) is similar to PTFE but is not fully fluorinated. PVDF liners can be produced with sufficient thickness to prevent permeation of gases so that liner venting is not required. PVDF resins are produced in accordance with ASTM D 3222 with material parameters specified by the designation of either type 1 (class 1 or 2) or type 2. PVDF lined pipe and fittings are manufactured to conform to ASTM F 491. Polyvinylidene chloride (PVDC) is a proprietary product of Dow Chemical (trade name Saran). PVDC is often used in applications where purity protection is critical. PFA resins are manufactured according to ASTM D 729, and lined piping and fittings are manufactured to conform to ASTM F 599. Polypropylene (PP) lined pipe is typically inexpensive compared to other lined plastic piping systems. In addition, PP does not allow permeation; therefore, liner venting is not required. Physical parameters (e.g., density, tensile strength, flexural modulus) of PP materials are specified by cell classification pursuant to ASTM D 4101. Additional material requirements may be added using the ASTM D 4000 suffixes; for example, W = weather resistant. The manufacture of PP lined pipe and materials are in accordance with ASTM F 492. Perfluoroalkoxyl (PFA) is a fully fluorinated polymer that is not affected by chemicals commonly found in chemical processes. Depending upon process conditions PFA will absorb some liquids, however, including benzaldehyde, carbon tetrachloride, toluene, ferric chloride, hydrochloric acid, and other liquids. PFA lacks the physical strength of PTFE at higher temperatures and fails at 1/4 of the life of PTFE under flexibility tests. PFA resins are manufactured according to ASTM D 3307, and lined piping and fittings are manufactured to conform to ASTM F 781.
Table: ANSI Class 125 and Class 150 Systems for Lightly Oiled Bolting Pipe Size, mm (in) 25 (1) 40 (1½) 50 (2)
Number of Bolts 4 4 4
Bolt Bolt Torque, N-m (ft-lb) Diameter PVDC PP PVDF PTFE mm (in) 14 (½) 41 (30) 37 (35) 75 (55) 34 (25) 14 (½) 54 (40) 102 (75) 81 (60) 75 (55) 16 (5/8) 61 (45) 149 169 102 (110) (125) (75) 65 (2½) 4 16 (5/8) 75 (55) 169 N.A. N.A. (125) 80 (3) 4 16 (5/8) 95 (70) 169 169 149 (125) (125) (110) 100 (4) 8 16 (5/8) 68 (50) 190 169 129 (140) (125) (95) 150 (6) 8 20 (3/4) 129 (95) 305 305 169 (225) (225) (125) 200 (8) 8 20 (3/4) 217 305 305 258 (160) (225) (225) (190) 250 12 24 (7/8) N.A. 468 N.A. 271 (10) (345) (200) Notes: This torques is only valid for lightly oiled ASTM A 193 bolts and nuts. Lightly oiled is considered WD-40, (WD-40 is a registered trademark of WD-40 Company, San Diego, CA) or equivalent. N.A. = Part is not available from source. Source: Crane/Resistoflex, “Plastic Lined Piping Products Engineering Manual,” p. 54. Table: ANSI Class 300 Systems for Lightly Oiled Bolting Pipe Number Diameter Bolt Torque, N-m (ft-lb) Size of mm (in) PVDC PP PVDF PTFE mm (in) Bolts Bolt 25 (1) 4 16 (5/8) 37 (35) 61 (45) 95 (70) 41 (30) 40 (1½) 4 16 (5/8) 81 (60) 149 230 108 (110) (170) (80) 50 (2) 8 16 (5/8) 34 (25) 75 (55) 115 (85) 54 (40) 80 (3) 8 20 (3/4) 54 (40) 136 210 88 (65) (100) (155) 100 (4) 8 20 (3/4) 81 (60) 230 305 149 (170) (225) (110)
150 (6) 12
20 (3/4)
88 (65)
224 305 115 (85) (165) (225) 200 (8) 12 24 (7/8) 169 441 495 203 (125) (325) (365) (150) Note: This torques is only valid for lightly oiled ASTM A 193, B7 bolts and ASTM A 194, 2H nuts. Lightly oiled is considered WD-40 (WD-40 is a registered trademark of WD-40 Company, San Diego, CA) or equivalent. Source: Crane/Resistoflex, “Plastic Lined Piping Products Engineering Manual,” p. 54.
Table: ANSI Class 125 and Class 150 Systems for Teflon - Coated Bolting Pipe Size mm (in) 25 (1) 40 (1½) 50 (2) 65 (2½) 80 (3) 100 (4) 150 (6) 200 (8)
Number of Bolts 4 4 4 4 4 8 8 8
Diameter mm (in) Bolt 14 (½) 14 (½) 16 (5/8) 16 (5/8) 16 (5/8) 16 (5/8) 20 (3/4) 20 (3/4)
Bolt Torque, N-m (ft-lb) PVDC PP PVDF PTFE 27 (20) 41 (30) 41 (30) 37 (35) 68 (50) 37 (35) 41 (30) 75 (55)
34 (25) 75 (55) 95 (70) 122 (90) 122 (90) 122 (90) 102 (75) 102 (75)
54 (40) 61 (45) 122 (90) N.A. 122 (90) 122 (90) 102 (75) 102 (75)
20 (15) 54 (40) 68 (50) N.A. 95 (70) 81 (60) 68 (50) 102 (75) 250 12 24 (7/8) N.A. 339 N.A. 203 (10) (250) (150) 300 12 24 (7/8) N.A. 339 271 (12) (250) (200) Notes: This torques is valid only for Teflon-coated ASTM A 193, B7 bolts and ASTM A 194, 2H nuts. N.A. = Part is not available from source. Source: Crane/Resistoflex, “Plastic Lined Piping Products Engineering Manual,” p. 55.
Table: ANSI Class 300 Systems for Teflon - Coated Bolting
Pipe Size mm (in) 25 (1) 40 (1½) 50 (2) 80 (3) 100 (4) 150 (6) 200 (8)
Number of Bolts 4 4 8 8 8 12 12
Diameter mm (in) Bolt 16 (5/8) 20 (3/4) 16 (5/8) 20 (3/4) 20 (3/4) 20 (3/4) 24 (7/8)
Bolt Torque, N-m (ft-lb) PVDC PP PVDF PTFE 41 (30) 34 (25) 27 (20) 34 (25) 41 (30) 41 (30) 129 (95)
37 (35) 61 (45) 27 (20) 61 (45) 95 (70) 41 (30) 61 (45) 95 (70) 41 (30) 61 (45) 81 (60) 34 (25) 95 (70) 102 (75) 61 (45) 95 (70) 102 (75) 37 (35) 312 346 163 (230) (255) (120) Notes: This torques is valid only for Teflon-coated ASTM A 193, B7 bolts and ASTM A 194, 2H nuts. Source: Crane/Resistoflex, “Plastic Lined Piping Products Engineering Manual,” p. 55. Table: Plastic Liner Material Properties Liner Material
Shell Material
PVC
--
PVDC
Carbon steel Carbon steel, Aluminium Carbon steel Carbon steel, TP304L Stainless steel Carbon steel Carbon steel Carbon steel Carbon
PE
PP PTFE
FEP PFA ETFE PVDF
Specific Tensile Gravity Strength, MPa (psi) 1.45 41.4 (6,000) 1.75 18.6 (2,700) 0.94 8.27 (1,200)
Available Maximum Size Temperature, Range, C (F) mm (in) -82 (180)
0.91
31.0 (4,500) 17.2 (2,500)
25 to 300 107 (225) (1 to 12) 25 to 300 232 (450) (1 to 12)
23.4 (3,400) 24.8 (3,600) 44.8 (6,500) 31.0
25 to 750 (1 to 30) 25 to 750 (1 to 30) as required* 25 to 200
2.17
2.15 2.15 1.7 1.78
25 to 200 79 (175) (1 to 8) 50 to 200 66 (150) (2 to 8)
204 (400) 260 (500) 150 (300) 135 (275)
steel (4,500) (1 to 8) ECTFE Carbon 1.68 48.3 25 to 200 150 (300) steel, (7,000) (1 to 8) Stainless steel Note: *Typically liquid applied; availability based upon shell piping availability.
Table: Liquid-Applied Coating Thickness Material
Total Dry Film Thickness Range (ETFE, 50 to 125 µm (2 to 5 mils)
Fluoropolymers ECTFE) PVDF 500 to 1,500 µm (20 to 60 mils) Source: NACE, RP 0181-94, p. 3. Table: Typical PVDF Liner Thickness Required to Prevent Permeation Nominal Pipe Size, Liner Thickness, mm (in) mm (in) 25 (1) 3.81 (0.150) 40 (1 ½) 4.07 (0.160) 50 (2) 4.37 (0.172) 80 (3) 4.45 (0.175) 100 (4) 5.26 (0.207) 150 (6) 5.54 (0.218) 200 (8) 5.54 (0.218) Source: Reprinted from Schweitzer, Corrosion-Resistant Piping Systems, p. 182, by courtesy of Marcel Dekker, Inc. b. Plastic Lined Piping Construction The plastic lined pipe piping is joined using flanges or mechanical couplings and fittings that are normally flanged. Some manufacturers can provide pre-bent pipe sections to avoid the use of flanged elbows. Use of pre-bent pipe sections requires that the design take into account the manufacturer’s standard bend radius, which is often larger than the bend radius for conventional elbows.
11.3 Other Lined Piping Systems The elastomeric and rubber materials most commonly used as liner materials include natural rubber, neoprene, butyl, chlorobutyl, nitrile, and EPDM, which tend to be less expensive than other liners. Design criteria that need to be considered before selecting elastomeric and rubber lined piping systems include: corrosion resistance, abrasion resistance, maximum operating temperature, and potential contamination of conveyed material. Elastomeric and rubber linings vary in thickness from 3.2 to 6.4 mm (1/8 to 1/4 in). Lined pipe is available from 40 to 250 mm (1½ to 10 in), standard, at ratings of 1.03 MPa (150 psi) or 2.06 MPa (300 psi). Joining is typically accomplished through the use of flanges. Glass-lined piping systems are commercially available with carbon steel outer piping in sizes of 25 to 300 mm (1 to 12 in), standard. Joining is accomplished using class 150 split flanges, although class 300 split flanges are also available as options. A PTFE envelope gasket is recommended. Stress is to be avoided; expansion joints should be used to isolate vibration and other stresses from the piping system. Sudden changes in process temperatures should also be avoided. Nickel-lined piping systems are available in sizes from 40 to 600 mm (1½ to 24 in) with liner thickness of 0.0008 to 0.015 inches. Joining is accomplished either by welding or flanging, with welding the preferred method.
12 Jacketed Piping 12.1. General Jacketed piping system design has not been standardized. If possible, the use of double containment piping should be deferred until design and construction standards are published by a national standards organization, such as ASTM. Due to the nature of the fluids transported in jacketed piping systems, the primary standard for the design of these systems is the ASME B31.3, Chemical Plant, and Petroleum Refinery Piping Code. a. Regulatory Basis: Double wall piping systems are available to provide secondary containment. The double containment piping system is composed of an outer pipe that completely encloses an inner carrier pipe. b. Design Requirements: Many options seem to exist for the combination of different primary and secondary piping systems based on physical dimensions. However, the commercial availability of components must be carefully reviewed for the selected materials of construction. Availability of piping sizes, both diameter and wall thickness; joining methods; and pressure ratings may preclude the combination of certain primary and secondary piping system materials. Some of these systems may have been conceptualized without detailed engineering of system components. c. Material Selection: Material compatibility should consider the type and concentration of chemicals in the liquid, liquid temperature, and total stress of the piping system. However, it must be remembered that cracking, such as stress corrosion cracking and environmental stress cracking, is a potentially significant failure mechanism in jacketed piping systems. Differential expansion of inner and outer piping can cause reaction loads at interconnecting components. These loads can produce tensile stresses that approach yield strengths and induce stress cracking at the interconnection areas. Material combinations may be classified into three main categories: (1) The primary and secondary piping materials are identical except for size, for example, ASTM A 53 carbon steel and A 53 carbon steel, respectively; (2) The primary and secondary piping are the same type of materials but not identical, for example, 316L stainless steel and A 53 carbon steel; and (3) Different types of materials are used, for example, PVDF as primary and A 53 carbon steel as secondary. Following Table provides a further breakdown and description of these three groups. d. Thermal Expansion: As discussed in the previous chapters, when a piping system is subjected to a temperature change, it expands or contracts accordingly. Jacketed piping systems have additional considerations, including expansion-contraction forces occurring between two potentially different, interconnected piping systems. Thermal stresses can be significant when flexibility is not taken into account in the design. For a double containment piping system, the primary and secondary piping systems must be analyzed both as individual systems and as parts of the whole. The basic correlations
between the systems are: (1) the primary piping system has a greater temperature change; and (2) the secondary piping system has a greater temperature change. Because of the insulating effect of the secondary piping system, the primary piping system usually only exhibits a larger temperature induced change when the process dictates, for example, when a hot liquid enters the piping system. In both above grade and buried systems, secondary piping system expansions are typically compensated for with expansion loops, changes in direction, or a totally restrained system. Expansion joints are not recommended for this use due to potential leaks, replacement and maintenance, unless they can be located in a tank or vault. To accommodate the dimensional changes of the primary piping system in expansion loops and change of direction elbows, secondary piping systems are often increased in size. Another alternative is to fully restrain the primary piping system. Figure demonstrates the result of differential movement between the piping systems without full restraint, and following Figure depicts an expansion loop with an increase to the secondary piping diameter. Totally restrained systems are complex. Stresses are induced at points of interconnection, at interstitial supports, and at other areas of contact. For rigid piping systems, restraints are placed at the ends of straight pipe lengths and before and after complex fittings to relieve thermal stress and prevent fitting failure. Plastic piping systems relieve themselves through deformation and wall relaxation, potentially leading to failure. Totally restrained systems should undergo a stress analysis and a flexibility analysis as part of the design. The combined stress on the secondary piping system is the result of bending, as well as torsion, internal hydrostatic and thermal expansion induced axial stresses.
Table: Double Containment Piping Material Combinations Category Primary Secondary Comments 1
M
M
Used with elevated temperatures and pressures. Good structural strength and impact resistant. May be required by fire or building codes. Cathode protection required if
Common Materials CS, 304 SS, 304L SS, 316 SS, 316L SS, 410 SS, Ni 200, Ni 201, Cu/Ni alloys
1
TS
TS
1
TP
TP
2
M
M
2
TS
TS
buried. Common for above grade and buried use for organic, inorganic, and acid wastes/chemicals. Good chemical resistance and structural strength. Conductive to field fabrication. Easily joined and fabricated. Resistant to soil corrosion and many chemicals. May be restricted by fire/building codes. Impact safety may require safeguards. May be required by fire codes or mechanical properties. Galvanic actions must be controlled at crevices and Interconnections. Cathode protection required if buried. Not advisable to combine resin grades. Epoxy and polyester resins are most economical.
Polyester resin, epoxy resin, Vinyl ester resin, furan resin
PVC, CPVC, HDPE, PP, PVDF, ECTFE, ETFE, PFA
CS-SS, Cu/Ni alloy CS, CSNi, CS-410 SS
Polyesterepoxy, vinyl esterepoxy, Vinyl ester-
polyester 2
TP
TP
3
M
TS
3
M
TP
3
M
O
3
TS
M
Common for above grade and buried acid/caustic use. Economical many commercial systems are available. Common and economical. Practical interconnections have been developed. Good for buried use, may eliminate cathode protection requirements. Common and economical. Good for buried use, may eliminate cathode protection requirements. May be limited by fire or building codes. Limited practical use except for concrete trench. Ability for leak detection is a concern. Common for above grade systems requiring thermo set chemical resistance and metallic mechanical
Many PVDF-PP, PVDFHDPE, PP- DPE
Epoxy-M (CS, SS, Ni, Cu), PolyesterM (CS, SS, Ni, Cu)
HDPE M (CS, SS), PVDF- M (CS, SS), PP-M (CS, SS)
Concrete trench M
Many
properties. Can meet category “M” service per ASME code. 3
TS
TP
3
TS
O
3
TP
M
3
TP
TS
3
TP
O
Economical. Epoxy-TP Good for buried (HDPE, applications. PVC, PP), PolyesterTP (HDPE, PVC, PP) Limited practical Concrete use except for trench concrete trench. TS Ability for leak detection is a concern. Common for Many above grade systems requiring thermo set chemical resistance and metallic mechanical properties. Can meet category “M” service per ASME code. Limited in use - Limited thermoplastic chemical resistance needed with thermo set mechanical properties. May not meet UL acceptance standards. Limited practical Concrete use except for trench concrete trench or TP, pipe. Ability for Concrete leak detection is a pipe -
3
O
M
concern. PVC Interconnections CS-glass, may be difficult. CS-clay Good for protection of brittle materials.
Notes: The primary piping material is listed first on primarysecondary combinations. Legend: M - metallic materials; TS - thermo set materials; TP - thermoplastic materials; and O - other non-metallic materials Source: Compiled by SAIC, 1998.
a. Before Thermal Expansion
b. After Thermal Expansion
Figure: Primary Piping Thermal Expansion
Dire ction of Move me nt Figure : Double Containme nt Piping Expansion Loop Configuration If the value of the combined stress, Sc, is less than the design stress rating of the secondary piping material, then the totally restrained design can be used. When double containment piping systems are buried, and the secondary piping system has a larger temperature change than the primary system, the ground will generally provide enough friction to prevent movement of the outer pipe. However, if extreme temperature differentials are expected, it may be necessary to install vaults or trenches to accommodate expansion joints and loops. For double containment systems located above grade, with secondary piping systems that have a larger temperature differential than primary systems, two common solutions are used. First, expansion joints in the outer piping can accommodate the movement. Second, the secondary piping can be insulated and heat traced to reduce the potential expansion-contraction changes. The latter would be particularly effective with processes that produce constant temperature liquids; therefore, the primary piping is relatively constant. Piping Support: Support design for double containment piping systems heeds the same guidelines as for the piping material used to construct the containment system. The support design is also based on the outside pipe size. Spans for single piping systems of the same material as the outer pipe may be used. The same recommendations may be applied for burial of double containment piping systems as for the outer containment pipe material. The following equation approximates the maximum spacing of the secondary piping system guides, or interstitial supports. The maximum guide spacing should be compared to the maximum hanger spacing (at maximum operating temperature) and the lesser distance used. However, the flexibility of the system should still be analyzed using piping stress calculations to demonstrate that elastic parameters are satisfied.
12.2
Piping Sizing
The method for sizing of the carrier pipe is identical to the methods required for single wall piping systems as explained in previous chapters. a. Secondary Pipe: Secondary piping systems have more factors that must be considered during sizing. These factors include secondary piping function, such as drain or holding, pressurized or nonpressurized requirements, fabrication requirements, and type of leak detection system. The assumption has to be made that at some point the primary piping system will leak and have to be repaired, thus requiring the capability to drain and vent the secondary piping system. Most systems drain material collected by the secondary piping system into a collection vessel. Pressurized systems, if used, are generally only used with continuous leak detection methods, due to the required compartmentalization of the other leak detection systems. Friction loss due to liquid flow in pressurized secondary piping systems is determined using the standard equations for flow in pipes with the exception that the hydraulic diameter is used, and friction losses due to the primary piping system supports have to be estimated.
12.3 Jacketed Piping Testing Testing requirements, methods, and recommendations for double containment and lined piping systems are identical to those pertaining to the outer pipe material. The design of lined piping systems includes the provision for pressure testing both the primary and secondary systems. Testing is specified in the same manner as other process piping systems. The design of each piping system contains the necessary devices required for safe and proper operation including pressure relief, air vents, and drains. Pressurized secondary piping systems are equipped with pressure relief devices, one per compartment, as appropriate. Care should be taken with the placement of these devices to avoid spills to the environment or hazards to operators. Low points of the secondary piping system should be equipped with drains, and high points should be equipped with vents. If compartmentalized, each compartment must be equipped with at least one drain and one vent. Drains and vents need to be sized to allow total drainage of liquid from the annular space that may result from leaks or flushing. Table: Common Orifice Coefficients Condition Cc Cv Short tube with no separation of fluid flow from 0.82 1.00 walls Short tube with rounded entrance 0.98 0.99 Source: Reprinted from Schweitzer, Corrosion-Resistant Piping Systems, p. 414, by courtesy of Marcel Dekker, Inc.
12.4 Leak Test Leak test is one of the main principles of lined piping systems. Any fluid leakage is to be contained by the secondary piping until the secondary piping can be drained, flushed, and cleaned; and the primary piping system failure can be repaired. Without leak detection, the potential exists to compromise the secondary piping system and release a hazardous substance into the environment. Early in the design of a double containment piping system, the objectives of leak detection are established in order to determine the best methods to achieve the objectives. Objectives include the following: - Need to locate leaks; - Required response time; - System reliability demands; and - Operation and maintenance requirements. The Leak is detected properly and correctly by measuring the conductance or impedance of the Cable, called Cable Leak Detection Systems, by measuring conductivity, pH, liquid level, moisture, specific ion concentrations etc. by a Probe called Probe Systems and by Visual Inspection as mentioned in detail below: a. Cable Leak Detection Systems: Cable detection systems are a continuous monitoring method. The purpose of this method is to measure the electrical properties, i.e. conductance or impedance of a cable; when properties change, a leak has occurred. These systems are relatively expensive compared to the other methods of leak detection. Many of the commercially available systems can determine when a leak has occurred, and can also define the location of the leak. Conductance cable systems can detect the immediate presence of small leaks, and impedance systems can detect multiple leaks. However, it must be remembered that these types of systems are sophisticated electronic systems and that there may be problems with false alarms, power outages, and corroded cables. Design requirements for these systems include: access, control panel uninterruptible power supply (UPS), and installation requirements. Access ports should be provided in the secondary piping system for installation and maintenance purposes. The ports should be spaced similar to any other electrical wiring: - At the cable entry into and exit from each pipe run; - After every two changes in direction; - At tee branches and lateral connections; - At splices or cable branch connections; and - After every 30.5 m (100 feet) of straight run. Power surges or temporary outages will set off alarms. To avoid such occurrences, consideration should be given to UPS. Installation requirements for a cable system include the completing of testing and thorough cleaning and drying of the secondary piping system prior to installation to avoid false alarms. In addition, a minimum annular clearance of 18 mm (3/4 in) for conductance cables and 38 to 50 mm (1-1/2 to 2 inches) for impedance cables is required to allow installation. These values may vary between manufacturers. b. Probe Systems: Probes that measure the presence of liquids through conductivity, pH, liquid level, moisture, specific ion concentrations, pressure, and other methods are used as sensing elements in leak test. The double containment piping systems are separated into compartments with each
compartment containing a probe with probe systems. Leaks can only be located to the extent to which the compartment senses liquid in the secondary containment piping. c. Visual Inspection: Visual systems include the use of sumps and traps; installation of sight glasses into the secondary piping system; equipping the secondary piping system with clear traps; and use of a clear secondary piping material. Some manufacturers offer clear PVC. Visual systems are often used in addition to other leak detection methods.
13 Piping Painting 13.0
General
The integrity and life of a piping system is dependent upon corrosion control. The internal corrosion of piping systems is controlled by the selection of appropriate materials of construction, wall thickness, and linings and by the addition of treatment chemicals. The external surfaces of all uninsulated Carbon Steel, Low Alloy Steel & Alloy Steel piping, working temperature from 800C to 4000C, installed above ground exhibits corrosion, which is developed by the presence of moisture, particulates, sulphur compounds, nitrogen-based compounds, and salt. This type of corrosion is uniform and common. Besides selecting a material of construction that is appropriate for the ambient environment, the primary method of corrosion control in above grade piping system is the application of painting as protective coatings. However, a stray current survey must be performed to ensure that electrical currents have not been created through the piping support system. The external corrosion is controlled through proper materials of construction. However, Painting is required for corrosion control when metallic piping systems are applied
13.1
Painting Applicable Codes
Applicable Codes: ASTM D344 IS 101 IS 161 IS 2074 IS 2379 IS 2932
: Testing Method for painting coverage of the surface. ASTM D1640 : The Testing method for primer. : Test Methods for ready mixed paints and enamels. : Heat Resisting Paints. : Indian Standard for ready mixed paint, Red Oxide Zinc Chromate Primer. : Aluminium Paint for general purpose in two pack of Dry Powder and Liquid and colour Coding. : Indian Standard Specification for Enamel, Synthetic, and Exterior Primer and Finish Coat. NACE No.5 : National Association of Corrosion Engineers,
U.S.A (NACE) SIS-05 5900 SSPC SP-1
: Swedish Institution’s Standard for Surface Preparation before Painting of steel. : Steel Structure Painting Council for surface preparation with Solvent for painting before Tape
Coating. SSPC SP-2
: Steel Structures Painting Council, U.S.A, Surface Preparation Specifications for Manual or Hand Tool Cleaning. : Steel Structure Painting Council for surface preparation with Power Tool SSPC SSPC SP-5 : Steel Structures Painting Council, U.S.A Surface Preparation Specifications by Blast cleaning to White metal (First Quality) SSPC SP-6 : Surface Preparation Specifications by Blast
SSPC SP-3
cleaning SSPC SP-7
to commercial Blast (Third Quality) : Surface Preparation Specifications by Blast
SSPC SP-10
to Brush-Off Blast cleaning (fourth Quality) : Surface Preparation Specifications near White
cleaning
Metal SSPC SP-12
(Second Quality) : Steel Structures Painting Council, U.S.A Surface Preparation
13.2
Painting Materials
Paint Materials: Paint is a liquid or liquefiable or mastic composition, which is converted to an opaque solid film after application to a surface or substrate in a thin layer. It is most commonly used to protect rusting, corrosion or provide colour or texture to the objects. (i) Pigment: Pigments are granular solids incorporated into the paint to contribute colour, toughness, texture, and to give the paint some special properties like to protect the substrate from the harmful effects of ultraviolet light or simply to reduce the cost of the paint. Alternatively, some paints contain dyes instead of or in combination with pigments. Pigments by chemical composition are, such as, Cadmium pigments; Carbon pigments; Chromium pigments; Cobalt pigments; Copper pigments; Iron oxide pigments; Clay earth pigments (iron oxides); Lead pigments; Mercury pigments (vermilion); Titanium pigments; Ultramarine pigments; and Zinc pigments. (ii) Binder or Resins: The binder (Resins) is the actual film forming component of paint, which must be present in the paint. Other components are optional, depending on the desired properties of the cured film of the paint. The binder imparts adhesion, binds the pigments together, and strongly influences such properties as gloss potential, exterior durability, flexibility, and toughness. Binders include synthetic or natural resins such as cement, alkyds, acrylics, vinyl-acrylics, vinyl acetate/ethylene (VAE), polyurethanes, polyesters, melamine resins, epoxy, or oils. Binders can be categorized according to drying, or curing mechanism. The four most common are (i) simple solvent evaporation, (ii) oxidative cross linking, (iii) catalyzed/cross linked polymerization, and (iv) coalescence. Note that drying and curing are two different processes. Drying generally refers to evaporation of the solvent or thinner, whereas curing refers to polymerization of the binder. Paints that dry by simple solvent evaporation and contain a solid binder dissolved in a solvent are known as lacquers. A solid film forms when the solvent evaporates, and because the film can re-dissolve in solvent, lacquers are not suitable for applications where chemical resistance is important. Classic nitrocellulose lacquers fall into this category. Lacquers have better UV resistance and lower corrosion resistance. Paints that cure by "catalyzed" polymerization are generally two package coatings that polymerize by way of a chemical reaction initiated by mixing resin and curing agent/hardener, and which cure by forming a hard plastic structure. Depending on composition they may need to dry first, by evaporation of solvent. Classic two package epoxies or polyurethanes would fall into this category. (III) Solvent: The main purposes of the solvent are to adjust the curing properties and viscosity of the paint. It is volatile and does not become part of the paint film. It also controls flow and application properties, and affects the stability of the paint while in liquid state. In order to spread heavier oils (i.e. linseed) as in oil-based interior house paint, thinner oil is required. These volatile substances impart their properties temporarily and once the solvent has evaporated or disintegrated, the remaining paint is fixed to the surface. (IV) Additives: Paint can have a wide variety of miscellaneous additives, which are usually added in very small amounts and yet give a very significant effect on the product. Additives modify surface tension, improve flow properties, improve the finished appearance, increase wet edge, improve pigment stability, impart antifreeze properties, control foaming, and control skinning. Additives normally do not significantly alter the percentages of individual components in a formulation.
13.3 Primer Paint Materials Selections Primer Materials: All steel piping should be protected with a coating (painting) system, which has been proven acceptable in a normal or marine environment. Among the generic types, the following Paint Materials are currently in use: Wash Primer-Vinyl or Chlorinated Rubber Zinc Phosphate Primer: It is a chlorinated rubber medium elasticised with un-saphonifiable plastics pigmented with zinc phosphate and is available in a single pack. It contains solid by 30-40% by volume and provides a thickness of 50 microns per coat on the surface. It covers 6-8 square meter of surface per litre per coat. Zinc rich epoxy (Zinc Phosphate) Primer: It is a Polyamide cured epoxy resin medium pigmented with zinc chromate and is available in two packs. It contains solid by 35-40% by volume and provides a thickness of 35 microns per coat on the surface. It covers 12—13 square meter of surface per litre per coat. Zinc silicate inorganic Primer: It is a Polyamide cured Epoxy Resin medium pigmented with zinc Phosphate and is available in two packs. It contains solid by 35-40% by volume and provides a thickness of 35 microns per coat on the surface. It covers 12—13 square meter of surface per litre per coat. Red Oxide Zinc Chromate Primer: It is a modified phenol alkyd medium pigmented with red oxide and zinc chromate and is available in a single pack. It contains solid by 30-35% by volume and provides a thickness of 25 microns per coat on the surface. It covers 12—14 square meter of surface per litre per coat. Epoxy Red Oxide Zinc Phosphate Primer: It is a Polyamide cured Epoxy Resin medium pigmented with micaceous iron oxide and is available in two packs. It contains solid by 50% by volume and provides a thickness of 100 microns per coat on the surface. It covers 5-6 square meter of surface per litre per coat. Epoxy based tie coat Primer: It is a conventional alkyd based coating to be applied before application of acrylic Polyurethane and contains Polyamide cured epoxy resin medium and suitably pigmented and is available in two packs. It contains solid by 50-60% by volume and provides a thickness of 50 microns per coat on the surface. It covers 10—13 square meter of surface per litre per coat.
13.4 Finish Paint Materials Selections Synthetic Enamel: It is a Alkyd medium pigmented with superior quality water and weather resistant pigments and is available in single pack. It contains solid by 30-40% by volume and provides a thickness of 25 microns per coat on the surface. It covers 15-18 square meter of surface per litre per coat. This paint is suitable for application up to 80 0C. Acrylic – Polyurethane finish paint: It is an Acrylic resin and isocyanate hardener suitably pigmented and is available in two packs. It contains solid by 40% by volume and provides a thickness of 30-40 microns per coat on the surface. It covers 10-13 square meter of surface per litre per coat. This paint is suitable for application up to 80 0C. Chlorinated Rubber Finish Paint: It is a Plasticized chlorinated rubber medium pigmented with chemical and weather resistant pigments and is available in single pack. It contains solid by 30% by volume and provides a thickness of 30 microns per coat on the surface. It covers 10-12 square meter of surface per litre per coat. This paint is suitable for application up to 80 0C. High Build Epoxy finish coating: It is a Polyamide cured epoxy resin medium pigmented and is available in two packs. It contains solid by 60-65% by volume and provides a thickness of 100 microns per coat on the surface. It covers 6-7 square meter of surface per litre per coat. High build coal Tar epoxy coating: It is a Polyamine cured epoxy resin blended with Coal tar and is available in two packs. It contains solid by 65% by volume and provides a thickness of 100-125 microns per coat on the surface. It covers 6-7 square meter of surface per litre per coat. This paint is suitable for application up to 120 0C. Self-Priming Surface Tolerant High Build Epoxy coating: It is a Polyamide-amine cured epoxy resin suitably pigmented and is available in two packs. It contains solid by 65-80% by volume and provides a thickness of 125-150 microns per coat on the surface. It covers 4-5 square meter of surface per litre per coat. This paint is suitable for application up to 120 0C. Inorganic Zinc Silicate coating: It is a self-cured Ethyl silicate solvent-based Inorganic zinc coating and is available in two packs. It contains solid by 60% by volume and provides a thickness of 65-75 microns per coat on the surface. It covers 8-10 square meter of surface per litre per coat. This paint is suitable for application up to 120 0C. Heat resistant medium based Aluminium paint: It is a Heat Resistant Enamel varnish medium combined with Aluminium flakes and is available in two packs. It contains solid by 20-25% by volume and provides a thickness of 20 microns per coat on the surface. It covers 10-12 square meter of surface per litre per coat. This paint is suitable for application up to 250 0C. Heat resistant Silicone Aluminium paint: It is a Silicon resin pigmented aluminium flakes and is available in two packs. It contains solid by 20-25% by volume and provides a thickness of 20 microns per coat on the surface. It covers 10-12 square meter of surface per litre per coat. This paint is suitable for application up to 400 0C. Specially formulated polyamine cured coal for Epoxy coating: This paint is suitable for application up to 80 0C. Epoxy phenol coating: This paint is suitable for application up to 120 0C. Epoxy Siloxane coating: This paint is suitable for application up to 120 0C. The paint material should vary with type of environment envisaged in and around the plants. Three types of environment are considered for selection of paint system. The paint system is also given for
specific requirements. Table-1: Normal Environment-Paint. Primer Paint
Finish Paint
Temp. Range Red Oxide Zinc Chromate Synthetic Enamel 650C Epoxy Zinc Chromate Acrylic Polyurethane 800C Epoxy Red Oxide Zinc High Build Coal Tar 800C phosphate Epoxy Table-2: Corrosive Industrial Environment-Paint. Primer Paint
Finish Paint
Epoxy Zinc Chromate
Temp. Range Build 800C
Epoxy High Coating Epoxy Red Oxide Zinc High Build Coal Tar 800C phosphate Epoxy High Build Chlorinated Chlorinated Rubber 800C Rubber Zinc Phosphate
Table-3: Highly Corrosive Environment (Coastal and Marine Environment)-Paint. Primer Paint Epoxy Zinc Chromate
Finish Paint
Temp. Range Build 800C
Epoxy High Coating Epoxy Zinc Phosphate Epoxy High Build 800C Coating High Build Chlorinated Chlorinated Rubber 800C Rubber Zinc Phosphate Epoxy Red Oxide Zinc High Build Coal Tar 800C phosphate Epoxy
The following points should be considered important factors affecting the quality of painting in case of application of paint: Surface preparation. Temperature ranges (maximum-minimum) expected. Dry and/or wet surfaces. Chemical contamination expected. Location of equipment under consideration. Abrasion expected.
Application of coating system.
13.5
Painting
In the liquid application, paint can be applied by direct application using brushes, paint rollers, or compressed air. Paint application by spray is the most popular method in industry. In this, paint is atomized by the force of compressed air or by the action of high pressure compression of the paint itself, which results in the paint being turned into small droplets which travel to the article which is to be painted. Alternate methods are airless spray, hot spray, hot airless spray, and any of these with an electrostatic spray included. The opacity and the film thickness of paint may be measured using a drawdown card. After liquid paint is applied, there is an interval during which it can be blended with additional painted regions (at the "wet edge") called "open time." Primer: Primer is a preparatory coating put on materials before painting. Priming ensures better adhesion of paint to the surface, increases paint durability, and provides additional protection for the material being painted. It can also be used to block and seal stains. Primer is a paint product that allows finishing paint to adhere much better than if it was used alone. Primer is designed to adhere to surfaces and to form a binding layer that is better prepared to receive the paint. Paint Application Defects: The main reasons of paint failure after application on surface are the applicator and improper treatment of surface. Application Defects are attributed to: (i) Dilution: This usually occurs when the dilution of the paint is not done as per manufacturer’s recommendation. There can be a case of over dilution and under dilution, as well as dilution with the incorrect diluents. (ii) Contamination: Foreign contaminants added without the manufacturers consent which results in various film defects. (iii) Peeling/Blistering: Most commonly due to improper surface treatment before application and inherent moisture/dampness being present in the substrate. (iv) Chalking: Chalking is the progressive powdering of the paint film on the painted surface. The primary reason for the problem is polymer degradation of the paint matrix caused by attack by UV radiation in sunshine. (v) Cracking: Cracking of paint film is due to the unequal expansion or contraction of paint coats. It usually happens when the coats of the paint are not allowed to cure/dry completely before the next coat is applied. (vi) Erosion: Erosion is very quick chalking. It occurs due to external agents like air, water etc. (vii) Blistering: Blistering is due to improper surface exposure of paint to strong sunshine.
13.6
Surface Preparation
Adhesion of the paint film depends largely on to the surface preparation of the metal surfaces. If proper quality of surface preparation is maintained, the protective coating life will be more. In order to achieve the maximum durability of the paint, one or more of following methods should be followed for surface preparations: Manual or hand tool cleaning Mechanical or power tool cleaning. Blast Cleaning. Mill scale, rust, scale and foreign matter shall be removed fully to ensure that a clean and dry surface is obtained. The minimum acceptable standard in case of manual or hand tool cleaning should be St -.2 or equivalent, in case of mechanical or power tool cleaning, it should be St.-3 or equivalent, in case of blast cleaning it should be Sa 2½ or equivalent as per Swedish Standard SIS-055900 / ISO8501-1. Where highly corrosive conditions exist, and then blast cleaning should be Sa -3 as per Swedish Standards. Remove all other contaminants, oil, grease etc. by use of an aromatic solvent prior to surface cleaning. Blast cleaning should not be performed where dust can contaminate surfaces undergoing such cleaning or during humid weather conditions having humidity exceeding 85%. Irrespective of the method of surface preparation, the first coat of primer must be applied on dry surface within two hours. This should be done immediately and in any case it should not exceed 4 hours of cleaning of surface. In general, during unfavourable weather conditions, blasting and painting shall be avoided as far as practicable. Blast Cleaning: Air Blast Cleaning: The surface should be blast cleaned using one of the abrasives: A12 O3 particles chilled cast iron or malleable iron and steel at pressure of 7 kg/cm2 at appropriate distance and angle depending on nozzle size maintaining constant velocity and pressure. Chilled cast iron, malleable iron and steel should be in the form of shot or grit of size not greater than 0.055” maximum in case of steel and malleable iron and 0.04” maximum in case of chilled iron. Compressed air shall be free from moisture and oil. The blasting nozzles should be venture style with tungsten carbide or boron carbide or boron carbide as the materials for liners. Nozzles orifice may vary from 3/16” to 3/4”. On completion of blasting operation, the blasted surface shall be clean and free from any scale or rust and must show a grey white metallic lustre. Blast cleaning should not be done outdoors in bad weather without adequate protection or when there is dew on the metal, which is to be cleaned. Surface profile should be 35 to 50 micron depth with uniform to provide good key to the paint adhesion. If possible vacuum collector should be installed for collecting the abrasives and recycling. Water Blast Cleaning: Environmental, health and safety problems associated with abrasive blast cleaning restrict the application of Air Blast Cleaning in many installations. In such case, Water Blast Cleaning can be applied with or without abrasive and high pressure water blasting. The water used should be inhibited with sodium chromate or phosphate. The blast-cleaned surface should be washed thoroughly with detergents and wiped with solvent and dried with compressed Air. For effective cleaning abrasives are used. The most commonly used pressure for high pressure water blast cleaning for maintenance surface preparation is 3000 to 6000 psi at 35-45 litters per minute, which provides maximum cleaning. The water blast cleaned surface should be comparable to SSPC – SP 12 or NACE No. 5. The operation should be carried out as per SSPC guidelines for water Blast cleaning. The indicative values for sand injection is,
Air : 300 to 400 Cu. Ft/min. Water : 5-10 Litres/min. with corrosion inhibitor Sand : 200-400 lbs/hr. Nozzle : 0.5 to 1” dia Mechanical or Power tool cleaning: Power tool cleaning should be done by mechanical striking tools, chipping hammers, grinding wheels or rotating steel wire-brushes or buffing wheel. Excessive burnish of surface shall be avoided as it can reduce paint adhesion. On completion of cleaning, the detached rust mill scale etc. should be removed by clean rags or washed by water or steam and thoroughly dried with compressed air jet before application of paint. Manual or hand tool cleaning: Manual or hand tool cleaning is used only where safety problems restrict the application of other surface preparation procedure and hence, it does not appear in the specifications of paint systems. Hand tool cleaning normally consists of the following: Hand descaling and or hammering; Hand scraping; and Hand wire brushing. Rust, mill scale spatters, old coatings and other foreign matter should be removed by hammering, chipping, scrapping tools, emery paper cleaning, wire brushing or combination of the above methods. Equipments: All tools, brushes, rollers spray guns, abrasive material, hand or power tools for cleaning and all equipments, scaffolding materials, shot or wet abrasive blasting, water blasting equipments & air compressors etc. require to be used should be suitable for the work and all in good order and should be arranged by the contractor at site and in sufficient quantity. Mechanical mixing only should be used for paint mixing operations in case of two pack systems except that mixing of small quantities.
13.7
Paint Application
Surface should not be coated in rain, wind or in environment where injurious air borne elements exists, or when the steel surface temperature is less than 50 F above dew point, or when the relative humidity is greater than 85% or when the atmospheric temperature is below 400 F. Air spray application: Air spray application shall be in accordance with the following: The equipment used should be suitable for the intended purpose and shall be capable of properly atomising the paint to be applied. This shall be equipped with suitable pressure regulators and gauges. Traps or separators should be provided to remove oil and condensed water from the air. The Pressure on the material in the pot and of the air at the gun shall be adjusted for optimum spraying effectiveness. The atomising air pressure at the gun should be high enough to properly atomise the paint but not so high as to cause excessive evaporation of solvent, or loss by over spray. Airless spray application: Airless spray application should be in accordance with “Steel Structure Paint Manual” Vol. 1 & Vol. 2, or SSPC. Air less spray relies on hydraulic pressure rather than air atomisation procedure to the desired spray. An air compressor or electric motor is used to operate a pump to produce pressures of 1,000 to 6,000 psi. Paint is delivered to the spray gun at this pressure through a single hose within the gun; a single paint stream is divided into separate streams, which are forced through a small orifice resulting in atomisation of paint without the use of air. This results in more rapid coverage with less over spray. Airless spray usually is faster, cheaper, more economical and easier to use than conventional airs pray. In case of High Build epoxy coatings (two packs), pump with 30:1 ratio and 0.020-0.023” tip size will provide a good spray pattern. Ideally fluid hoses should not be less than 3/8” ID and not longer than 50 ft to obtain optimum results. Manual Application: Manual Application is carried out manually with the help of paintbrush. Where 6 O’ Clock position of pipe is not approachable for painting, a canvas strip or alternatively a tinplate strip, about 450 mm wide and 1.5m long is held under the pipe by two men, one each on either side of the pipe. The third man at side of the pipe pours liquid paint or coating paint on the sling. The men, holding this sling, move it up and down and walk slowly forward while fresh coating is poured on the pipe or canvas and they manipulate the sling so that an even coating is obtained all round the bottom of the pipe. Dryness of coated Surface: Another coat of paint shall be applied only after the preceding coat is dried. The material shall be considered dry for re-coating only after the minimum drying time given by the paint manufacturer. Another coat, then, can be applied without the development of any film irregularities such as lifting or loss of adhesion of undercoats. No paint shall be force dried under any conditions; otherwise, it will cause checking, and wrinkling, blistering formation of pores, or detrimentally affects the condition of the paint. No drier shall be added to paint on the job unless specifically called for in the manufacture’s specification for the paint. Paint shall be protected from rain, condensation, contamination, snow and freezing until it dries to the fullest extent practicable. Repair of damaged paint surface: Where painting has been damaged in handling and in transportation of pipe, the repair of damaged coating of erected or fabricated pipe shall be done as given below: Remove the primer from damaged area by mechanical scrapping and emery paper to expose the white metal or blast cleans the surface if possible. Feather the primer over the intact adjacent surface surrounding the damaged area by emery paper slowly. Apply fresh paint with the method as explain above to the cleaned area of damaged pre-erection and
shop priming.
13.8
Colour Coding
The colour code scheme is intended for identification of the individual piping. The System of colour coding consists of a ground colour and colour bands superimposed on it. Colour band shall be applied at the following location to At battery limit points Intersection points & change of direction points in piping ways. Other points, such as midway of each piping way, near valves, junction joints of service appliances, walls, on either side of pipe culverts. For long stretch / yard piping at 50M interval. At start and terminating points. As a rule minimum width of colour band shall conform to the following table:
Nominal pipe size
Width: L (mm)
3” NB and below Above 3” NB up to 6” NB Above 8” NB up to 12” OD Above 12” OD
25 mm 50 mm 75 mm 100
Equipment number shall be stencilled in black or white on each vessel, column, equipment & machinery (insulated or un-insulated) after painting. Line number in black or white shall be stencilled on all the pipe lines of more than of more than one location as directed by Engineer-inCharge, size of letter printed shall be as below: Column & vessels 150 mm (high) Pump, compressor and other machinery 50 mm (high) Piping 40-150 mm Storage tanks The storage tanks shall be marked as detailed in the drawing. Colour code for Defence Requirement: Following items shall be painted for camouflaging, if required by the client. All columns All tanks in offsite. Large Vessel. Spheres Two coats of selected finishing paint as per specification requirement shall be applied. Method of camouflaging: Disruptive painting for camouflaging shall be done in three colours in the ratio of 5:3:2 (all matt finish), SUCH AS, Dark Green - 5;Light Green - 3;Dark Medium - 2 Brown; Respectively The patches should be asymmetrical and irregular. The patches should be inclined at 30 degree to 60 degree to the horizontal. The patches should be continuous where two surfaces meet at an angle. The patches should not coincide with corners.
Slits and holes shall be painted in dark shades. Width of patches should be 1 to 2 meters.
13.9
Painting Inspection
All painting materials including primers and thinners brought to site by contractor for application shall be procured directly from manufactures as per specifications and shall be accompanied by manufacture’s test certificates. Paint formulations without certificates are not acceptable. The painting work shall be subject to inspection at all times. In particular, following stage wise inspection should be performed and contractor shall offer the work for inspection and approval of the same at every stage before proceeding with the next stage. The record of inspection shall be maintained in the registers. Stages of inspection are as follows: a. Material Testing: Manufacturer’s Test Certificate should be correlated with the requirement of characteristics of the paint with the codes, Standards and Specifications for confirmation of the same. If required, the samples should be sent to the laboratory for testing of the paint materials. The test required for evaluation of acceptance of painting materials for offshore application with reference to following Codes and Standards: Testing of Paint Materials Test Type ASTM Test Methods Density D 1475 Dipping properties D 823 Film Characteristics D1640 Drying time D 1737 / D 522 Flexibility D 3363 Adhesion D 2197 Abrasion resistance D968 / D1044 DFT per Coat As Per SSPC Guide Lines Storage Stability D 1849 Resistance to Humidity for 2000 D 2247 hrs Salt Spray for 2000 hrs B 117 Accelerated Weathering D 822 % Zn in DFT G 53
b. Surface preparation: The cleaning of the surface should be checked with the help of the photo comparator for maintaining the quality. c. Primer Coating: The thickness of each coat of the primer should be checked for Dry Film Thickness (DFT) to match with the requirement of the specification with the help of digital thickness measuring instrument, i.e. Elko meter. If the thickness is found less than the required thickness, the additional coat of the primer should be applied to obtain the required thickness. The thickness variation within 10% of the total thickness is within the acceptable limit. d. Finish Paint: The thickness of each coat of the finish paint should be checked for Dry Film Thickness (DFT) to match with the requirement of the specification with the help of digital thickness measuring instrument, i.e. Elko meter. If the thickness is found less than the required
thickness, the additional coat of the finish paint should be applied to obtain the required thickness. The thickness variation within 10% of the total thickness is within the acceptable limit. Maintenance: The consulting engineering firm for specific recommendations, specifications, and inspection services does the selection of paint. Tapes and extruded coatings should generally not be used on plant piping. Experience has shown that severe corrosion can occur beneath these protective materials without any visible evidence. Riser’s pipe should be protected in the seawater splash zone by providing another layer of pipe. The most commonly used methods to protect Risers pipe include: Steel doublers (1/2 inch or more additional metal thickness) and one of the paint systems. Vulcanised, shop applied neoprene rubber compounds ¼ inches to ½ inch thick. Monel sheathing. Epoxy sand coating. Moisture may be trapped at the top juncture of the vulcanised rubber with the painted steel, causing accelerated deterioration. This juncture should be periodically inspected visually and, if deemed necessary, by radiography. The top junction of the steel doublers should be seal welded. Passivation for Corrosion Control: Passivation is the spontaneous formation of an ultra-thin film of corrosion products known as passive film, on the metals surface that act as a barrier to further oxidation. The chemical composition and microstructure of a passive film are different from the underlying metal. Typical passive film thickness on aluminium, stainless steels and alloys is within 10 nanometres. The passive film is different from oxide layer or scale that is frequently formed at high temperatures and is in the micrometer thickness range. The passive film has the unique property of self-healing while the oxide layer or oxide scale does not. For example, when you scratch the surface of a stainless steel, the damaged passive film will be healed spontaneously by the instantaneous oxidation of chromium from the underlying metal. Passivation in natural environments such as air, water and soil at moderate pH is seen in such materials as aluminium, stainless steel, titanium, and silicon. Passivation is primarily determined by metallurgical and environmental factors. The effect of pH is recorded using Pourbaix diagrams, but many other factors are influential. Some conditions that inhibit passivation include: high pH for aluminium and zinc, low pH or the presence of chloride ions for stainless steel, high temperature for titanium (in which case the oxide dissolves into the metal, rather than the electrolyte) and fluoride ions for silicon. On the other hand, sometimes unusual conditions can bring on passivation in materials that are normally unprotected, as the alkaline environment of concrete does for steel rebar. Exposure to a liquid metal such as mercury or hot solder can often circumvent passivation mechanisms. Passivation is extremely useful in mitigating corrosion damage, however even a high-quality alloy will corrode if its ability to form a passivation film is hindered. Proper selection of the right grade of material for the specific environment is important for the long-lasting performance of this group of materials. If breakdown occurs in the passive film due to chemical or mechanical factors, the resulting major modes of corrosion may include (i) pitting corrosion, (ii) crevice corrosion and (iii) stress corrosion cracking. Inhibitors Reactive Coatings: The corrosive environment is controlled by inhibitors, which can often be added to it. These form an electrically insulating and/or chemically impermeable coating on exposed metal surfaces, to suppress electrochemical reactions. Such methods obviously make the system less sensitive to scratches or defects in the coating, since extra inhibitors can be made available wherever metal becomes exposed. Chemicals that inhibit corrosion include some of the salts in hard water (Roman water systems are famous for their mineral deposits), chromates, phosphates, polyaniline, other conducting polymers and a wide range of specially-designed chemicals
that resemble surfactants (i.e. long-chain organic molecules with ionic end groups).
14 Coating and Wrapping 14.1
General
In buried installations, leaks due to corrosion in metallic piping systems can cause environmental damage. Protective Coating on the external surface of pipe works well. The bases of selection for an exterior pipe coating involve chemical inertness, adhesiveness, electrical resistance, imperviousness, and flexibility to adjust to pipe deformation, thermal expansion/contraction and environmentally induced stress such as, wind induced shear. Obviously, the coating must be applied without holidays and remain undamaged, without cracks or pinholes.
14.2
Applicable Codes
AS 3894.1; ASTM D 4787; ASTM G 6;ASTM D 5162; BS 1344-11; ISO 2746; NACE RP0274; NACE RP0490; NACE RP0188; IEC 52ASTM D93; IS-3624; AWWA C203 and SSPC SP-7.
14.3
Coating & Wrapping Materials
Coal-tar Enamel: The Specification AWWA C203 provides the coal-tar enamel materials and the methods for application of coal-tar coating on the outer surface of the pipe, the thickness required and inspection of the coating. But the coal-tar enamel coating may develops a crack in the coating at low temperature under –200F and also gets adversely affected by prolonged pre-installation exposure to open and fluctuating atmospheric condition of heat and cold. To save the coating while storage for a prolonged period, a heat-reflective coating of whitewash, or red lead or aluminium paint over the coal-tar enamel coating is, usually, helpful. The enamel coating is imperfect method and sometimes develops imperfections and hence loss of the pipe thickness or pitting due to corrosion of the pipe. Wetting and drying of the soil cause the destruction of the coal-tar enamel coating. Rocks in the back filled material and chemical constituent of the earth because the destruction of the coal-tar enamels coating. The earth adheres to the coating tightly, and on drying, exerts a powerful stress which shears and tears the coating from the pipe surface. However, the Coal-tar enamel or Polyethylene coating is still applied on the outside surface of the pipe. Now days, the Polyethylene coating from 3 mm to 7 mm is applied on the full length of the pipe in the mill or some coating yard, specially meant for providing the coating on the full length of pipe, before dispatch of the pipe to the site for use in underground piping. Polyethylene Tape: Vinyl, polyethylene or polyvinyl chloride-butyl rubber tapes are spirally wound around the outside surface of pipe. But in case of the single layer of the coating, it is very difficult to obtain the water seal coating because of the bounding of overlap spiral joint and coating with the pipe surface. So, before application of the layer, a suitable bounding primer is applied on the pipe surface to provide perfect bound between the pipe surface and the coating layer. The application of double layers of the tape coating provides a satisfactory and perfect coating of the pipe. Primer: The primer should be fast drying, synthetic or chlorinated rubber synthetic plasticizersolvent based primer. The drying time should be at minimum. The flash point of volatile matter at 105-110 0C should be 75%. The following Primer materials are used in corrosion coating of underground piping. The primer should have the following properties: Drying Time Flash Point Volatile Matter (105 0C to 110 0 C) Viscosity Dry Film Thickness Coverage Adhesion Test
5 to 20 minutes > 230C, 75 % by Mass 35-60 seconds 25 microns/coat 6-10 M2/litre/coat Satisfactory
Coal-tar Tapes: The Tape consists of coal tar material supported on the fabric of the organic or Inorganic fibres. The fabric should be thin (0.3 mm) and weight 40 g/m 2, flexible, uniform mat, or tissue composed of glass fibres in an open structure bonded with a suitable coal tar. Heating Value
13000 BTU/LB (Minimum)
Softening Point Specific Gravity Ash Content Physical state Service Temperature Tape Thickness Weight Average Breaking Strength Adhesion Insoluble Content
23 0C-1210C 1.30 ± 0.05 0.5 Maximum Solid at atmospheric temperature 60-65 0C, 2.0 mm-2.5 mm 1.25 kg/m 2/mm 0.7 kN/m Satisfactory 95 % by weight in Petroleum Ether.
Rubber Tapes: The Tape consists of rubber material supported on the fabric of the organic or Inorganic fibres. Polyvinyl Chloride tapes: The Tape consists of Polyvinyl Chloride material supported on the fabric of the organic or Inorganic fibres. Polyethylene Tapes: The Tape consists of Polyethylene material supported on the fabric of the organic or Inorganic fibres. Vinyl Tapes: The Tape consists of Vinyl material supported on the fabric of the organic or Inorganic fibres. Butyl Rubber Tapes: The Tape consists of Butyl Rubber material supported on the fabric of the organic or Inorganic fibres. The manufacturers Test certificates, batch wise, should be submitted and correlated for all materials to be used on corrosion coating for the confirmation of the materials quality requirement. In absence of the manufacturers Test certificates, the sample of the materials should be sent to the approved laboratory for testing and acceptance of the same.
14.4
Surface Preparation
Surface Preparation (Manual cleaning): Wire brush, Emery Papers or hand tool should be used for cleaning the pipe surface properly. Hand tool cleaning normally consists of the following: Hand de-scaling or hammering Hand scraping Hand wire brushing Oil, Grease on the surface should be cleaned from the surface by flushing with a suitable solvent such as Xylene or 1:1:1 of Trichloroethylene and wiping with rugs. If required, the surface should be cleaned with the detergent after solvent cleaning. Rust, mill scale spatters, old coatings and other foreign matter should be removed by hammering, chipping, scrapping tools, emery paper cleaning, wire brushing or combination of the above methods. Surface Preparation (Power tool cleaning): If required, power tool cleaning should be done by mechanical striking tools, chipping hammers, grinding wheels or rotating steel wire-brushes or buffing wheel. Excessive burnish of surface shall be avoided as it can reduce paint adhesion. On completion of cleaning, the detached rust mill scale etc. should be removed by clean rags or washed by water or steam and thoroughly dried with compressed air jet before application of paint. Surface Preparation (Shot Blast Cleaning): The metal surface should be cleaned with shot blast to Sa 2 ½ with a surface profile of 30-50 micron depth and primer should be applied within 4 hours of completion of the shot blasting. Surface shall not be coated in rain, wind or in environment where injurious air borne elements exists, or when the steel surface temperature is less than 50 F above dew point, or when the relative humidity is greater than 85% or when the temperature is below 400 F.
14.5
Application
Primer Coating: Before application of the casting and wrapping, one coat of the suitable primer should be applied on the cleaned surface and should be made touch dry prior to the Tape application for the perfect bounding of the coating on the pipe surface. Coal Tar Coating Application: The Coal Tar Coating Application is carried out manually with the help of sling placed at 6 O’ Clock position of pipe. A canvas strip or tinplate strip about 450 mm wide and two men hold 1.5m long under the pipe. Liquid paint or liquid Coal Tar coating is poured on the sling at the top of the pipe. The men, holding this sling, move it up and down and walk slowly forward rubbing with the half of circumference of the pipe at bottom while fresh coating is poured on the pipe or canvas and they manipulate the sling so that an even coating is obtained all round the bottom of the pipe. Tape Coating Application: One layer of Tape Coating of 2.5 mm thickness is applied on dried primer on the pipe surface with 15 mm minimum overlap at the edge of the Tape per single wrap. The second coat of the primer is applied on the first layer of the tape Coating and let it be touch dry. Then, the second layer of the Tape Coat of 2.5 mm thickness is applied on the primed and touch dry surface. The primed surface should not be left exposed to the atmospheric condition for a long time, otherwise the bonding strength of the primer is reduced because of the dust deposition on the primed surface. While applying the Tape, it should be pulled out to take care that there is no air pockets or the air bubbles beneath the Tape and the Tape is in intimate contact with the primed surface. Cleaned Surface Inspection: During the surface preparation, the nozzle type, size, safety gauges, air pressure of the blast cleaning equipment should be checked. After the surface cleaning, the surface profile and cleanliness of the surface is checked visually as well as with the photo comparator of ISO 8501. Primer coating Inspection: After application of the primer, the primer dryness by touch dry method and the Dry Film Thickness are checked before application of the Tape Coating.
14.6
Inspection
Wrapped Coating Inspection: The following inspection should be carried out minimum for the coating/ tape Coating work: (i) Visual Inspection: The visual inspection of the coating is carried out for the cracks, trapped air, any damages, uniformity, any wrinkles, 15 mm overlapping width at the edge and irregularities. (ii) Tape Thickness Test: The thickness of the Tape should be measured with the calliper on the surfaces of pipe at 20 meter interval of the pipe length or on 5 to 6 tape pieces taken from the different coils of the tape at a pressure of 0.5 N/m2. The thickness with ± 0.1 mm is acceptable. (iii) Adhesion Test: The Adhesion Test should be carried out on each layer of the Tape Coating to determine the proper bonding between the tape and the primed surface. The adhesion test should be carried out at the atmospheric temperature between 10 0C to 27 0C. The tape should be cut 150 mm in length and 50 mm in width. The width of the tape should be pried up to 50 mm in length wise with the help of a flat blade and should be grasped firmly with the help of tool and should be pulled with a quick motion in the direction of the remaining 100 mm of the full 150 mm cut length of the tape. The adhesion test is satisfactory, when (i) the tape tears at the point of stripping or (ii) the fabric strips from the underlying tar component, leaving not more than 10% or less of the primer or bare metal exposed. After the adhesion test is over satisfactory, the total pilled out area with 25 mm minimum overlap should be repaired with the new Tape Coating. (iv) High Voltage Holiday Test: A High Voltage (1000 Volts) Holiday Detector is used to inspect the pinholes in the coating and wrapping of the pipe. Holiday Detector is portable with solid state, circuitry for the inspection of coating and wrapping on pipelines, (underground piping). (a) Trailing ground wire, 8” to 16” rolling spring electrodes wrapped around the pipe over the Coating, (b) Crest voltmeters to measure the voltage at which the inspection of coating is to be done, (c) Sealed lead oxide battery where fluid is not needed and nothing will spill out, (d) Spring pusher handle of high impact PVC with double vinyl covered air craft cable for high strength and (e) shock protection cable has positive lock to detector, and cannot slip out, and would not break, Spring Electrode is a plated square spring steel wire, sealed ball bearing in ends permits electrode to roll free, flat surface provides more bearing area, will not damage soft coatings and (f) High Voltage Holiday Detector with fully transistorised, loud, high-pitched signal horn, easily heard above the job noise. Each model can be set on one of six-voltage range. Recessed “on-off” push button prevents accidental activation. It is packed in a moulded, high impact shockproof ABS plastic case. Defect Detection: The detection is done by producing a spark near the electrode. The spark indicates a pinhole in the coating and wrapping which the technician repairs immediately. After repair work, the repaired coating is inspected again with the holiday detector. Holiday Detector test detects pinhole, porosity or flaws in insulated coatings It is essential that any pinhole, porosity or flaws which will eventually lead to corrosion are detected at the earliest possible stage, preferably immediately after the coating application. Holiday detector is suitable for all types of coatings like Fusion bonded epoxy, coal tar epoxy, paints, polyester, polyurethane, pipeline tapes, Heat shrinks and Asphalt. This versatile unit can be used to inspect protective coatings applied to pipelines, tanks, pilings, fire lines or buried pipelines of conductive surface.
The value of the test voltage is achieved by the dielectric or voltage strength of the coating thickness. Therefore 1000 micron would by approx 3kv to 5kv test voltage. Accurate voltage setting is achieved by adjusting a knob to desire voltage is displayed on a digital display with accuracy of ± 1% or in the step of 2KV. Holiday detectors with automatic fault detection feature installed which ensures that are detected at any voltage setting. The Instrument has low voltage battery indication for safeguard the batteries and ensures desired voltage all the time. The holiday detector is lightweight and overall weight with handle is approx 1.6 kg the test voltage is of low power and does not damage or cause burn marks on the coating. When the using holiday detector, there are a number of important safety features in-build to test voltage with high impedance and drops to zero when a fault is detected, earth cable is lockable to prevent accidental disconnection. There is a probe discharge path incorporated to prevent any static charge being maintained will allow coatings on concrete as well as steel and iron substrates to be tested. In view of the many different holiday testing applications there is an extensive range of accessories available including circular brushes for pipe work internal, rolling springs for pipe work externals, broad brushes to allow for quicker measurement of large surface areas and insulated extension rods. The holiday detector is supplied in a carrying case complete with high voltage prone handle, conductive rubber brush, neck strap, earth cable and batteries fitted. Other special size circular brushes and external rolling spring electrodes are supplied as per requirements. Caltechindia also supply high voltage measuring device generally called as Jeep Meter, PRM Meter to verify voltage of holiday detectors. Holiday detectors are a non-destructive detection method of testing. The Instrument can be used as per AS 3894.1, ASTM D 4787, ASTM G 6, ASTM D 5162, BS 1344-11, ISO 2746, NACE RP0274, NACE RP0490, NACE RP0188-88 standards.
15 Cathode Protection General: Cathode protection shall be provided for the following buried/submerged ferrous metallic structures and piping, regardless of soil or water resistivity: Natural gas propane piping; Liquid fuel piping; Oxygen piping; Underground storage tanks; Fire protection piping; Ductile iron pressurized piping under floor (slab on grade) in soil; Underground heat distribution and chilled water piping. Furthermore, certain types of processes pose safety problems if cathode protection is not properly installed and maintained. The Applicable Codes for Cathode Protection is NACE No.5. The galvanic series: The galvanic series (or electro potential series) determines the nobility of metals and semi-metals. When two metals are submerged in an electrolyte, while electrically connected, the less noble (base/cathode) will experience galvanic corrosion. The rate of corrosion is determined by the electrolyte and the difference in nobility. In a given environment (Aerated medium, Seawater), one metal will be either more noble or more active than the second metal, based on how strongly its ions are bound to the surface. Two metals in electrical contact share the same electrons, so that the "tug-of-war" at each surface is analogous to competition for free electrons between the two materials. Using the electrolyte as a host for the flow of ions in the same direction; the noble metal will take electrons from the active one. The resulting mass flow or electrical current can be measured to establish a hierarchy of materials in the medium of interest. The difference can be measured as a difference in voltage potential. Galvanic reaction is the principle upon which batteries are based. In Galvanic series, most noble metal is at top and the less noble (base/cathode) metal is at bottom. The order may change in different environments. The galvanic series of metals are given here is Copper at top to Stainless steel 316 (passive) Stainless Steel 304 (passive); Stainless Steel 316 (active); Nickel; Cast iron; Steel; Aluminium; and Zinc at bottom of the list. So, Zinc is the best metal to use as cathode. This hierarchy is called a Galvanic Series, and can be a very useful in predicting and understanding corrosion. The following is the galvanic series for seawater. Table: Galvanic Series of Metals Copper Stainless Steel (passive) Nickel (passive) Nickel-copper alloys Hastelloy A 4) Stainless Steel 316 1) Stainless Steel 430 2) Stainless Steel 410 3) Cast Iron Low-carbon Steel Cadmium
Aluminium Alloys Aluminium Zinc Anodic Protection: Anodic protection impresses anodic current on the structure to be protected (opposite to the cathode protection). It is appropriate for metals that exhibit passivity (e.g., stainless steel) and suitably small passive current over a wide range of potentials. Aluminium alloys often undergo a surface treatment. Electrochemical conditions in the bath are carefully adjusted so that uniform pores several manometers wide appear in the metal's oxide film. These pores allow the oxide to grow much thicker than passivation conditions would allow. At the end of the treatment, the pores are allowed to seal, forming a harder-than-usual surface layer. If this coating is scratched, normal passivation processes take over to protect the damaged area. Anodizing is very resilient to weathering and corrosion, so it is commonly used for building facades and other areas that the surface will come into regular contact with the elements. Whilst being resilient, it must be cleaned frequently. If left without cleaning Panel Edge Staining will naturally occur. It is used in aggressive environments, e.g., solutions of sulphuric acid. Cathode Protection: Cathode protection (CP) is a technique to control the corrosion of a metal surface by making that surface the cathode of an electrochemical cell. It is a galvanic corrosion of aluminium, such as, if a 5 mm thick aluminium alloy plate is physically (electrically) connected to a 10 mm thick mild steel structural support or pipe, Galvanic Corrosion occurred on the aluminium plate along the joint with the mild steel. Perforation of aluminium plate occurred within 2 years due to the large acceleration factor in galvanic corrosion. Factors such as relative size of anode, types of metal, and operating conditions (temperature, humidity and salinity) affect galvanic corrosion. The surface area ratio of the anode and cathode directly affects the corrosion rates of the materials.
Figure: Cathode for Corrosion protection Galvanic corrosion is often utilized in sacrificial anodes. Cathode protection systems are most commonly used to protect steel pipelines and tanks; steel pier piles, ships, and offshore oil platforms. It is sacrificial anode in the hull of a ship. For effective CP, the potential of the steel surface is polarized (pushed) more negative until the metal surface has a uniform potential. With a uniform potential, the driving force for the corrosion reaction is halted. For galvanic CP systems, the anode material corrodes under the influence of the steel, and eventually it must be replaced. The polarization is caused by the current flow from the anode to the cathode, driven by the difference in electrochemical potential between the anode and the cathode. A cathode is an electrode through which electric current flows out of a polarized electrical device. The direction of electric current is, by convention, opposite to the direction of electron flow. Impressed current cathode protection: For larger structures, galvanic anodes cannot economically
deliver enough current to provide complete protection. Impressed Current Cathode Protection (ICCP) systems use anodes connected to a DC power source (such as a cathode protection rectifier). Anodes for ICCP systems are tubular and solid rod shapes of various specialized materials. These include high silicon cast iron, RUST, mixed metal oxide or platinum coated titanium or niobium coated rod and wires. a. Cathode Protection Requirements: The comment of the consultant shall govern the application of cathode protection and protective coatings for buried piping systems, regardless of soil resistivity. The Electrical Design and Cathode Protection Codes provide the criteria for the design of cathode protection for aboveground, buried, and submerged metallic structures including piping. Cathode protection is mandatory for underground gas distribution lines or underground water storage tanks and underground piping systems located within 3 m (10 ft) of steel reinforced concrete. Unbounded coatings are defined in AWWA C105. b. Cathode Protection Methods: The galvanic corrosion is an electrochemical process in which a current leaves the pipe at the anode site, passes through an electrolyte, and re-enters the pipe at the cathode site. Cathode protection reduces corrosion by minimizing the difference in potential between the anode and cathode. The two main types of cathode protection systems, galvanic or sacrificial and impressed current are depicted. A galvanic system makes use of the different corrosive potentials that are exhibited by different materials, whereas an external current is applied in an impressed current system. The difference between the two methods is that the galvanic system relies on the difference in potential between the anode and the pipe, and the impressed current system uses an external power source to drive the electrical cell. c. Isolation Joints: When piping components such as pipe segments, fittings, valves, or other equipment coming out of underground, dissimilar materials are connected; an electrical insulator must be used between the components to eliminate electrical current flow. Complete prevention of metalto-metal contact must be achieved. Specification is made for dielectric unions between threaded dissimilar metallic components; isolation flanged joints between non-threaded dissimilar metallic components; flexible couplings for plain end pipe sections, and under special aboveground situations. For the flanged isolation joints complete isolation is required; additional non- metallic bolt isolation washers and full length bolt isolation sleeves are required. Dielectric isolation shall conform to NACE RP-0286. Copper water service lines will be dielectrically isolated from ferrous pipe. d. Installation Proper installation of isolation joints is critical. Installation procedures should follow the manufacturer's recommendations exactly. e. Isolation from Concrete A ferrous metallic pipe passing through concrete shall not be in contact with the concrete. A nonmetallic sleeve with waterproof dielectric insulation between the pipe and the sleeve shall separate the ferrous metal pipe. Ferrous metal piping passing through a concrete thrust block or concrete anchor block shall be insulated from the concrete or cathode protected.
a. Galvanic Anode System b. Impressed Figure: Current System of Cathode Protection Methods
16 Piping Insulation
16.0
General
The basic fundamental of the thermal insulation in the industrial engineering is the conservation of the energy. All engineering operations are based on this fundamental principle. The heat insulation of piping contributes a major role in the operation and proper functioning of the miscellaneous operation in the industries. The insulation, basically, reduces the heat transfer and heat loss from the bare heated surface of the pipe, which is a big amount in a plant. It cannot stop the heat loss but certainly reduces it to the negligible amount. Followings are the two rules of the heat loss from the bare pipe: (1) the heat loss from the bare pipe surface is due to the temperature difference of the pipe surface and the surrounding air around the pipe. And the rate of heat loss increases with decrease of the temperature gradient between the two; (2) the heat loss from the bare pipe surface is due to the air circulation around the pipe and the rate of heat loss from a surface, maintained at the constant temperature, is greatly increased by increase in the rate of air circulation around the bare pipe surface.
16.1
Applicable Codes
ASTM C302 ASTM C335 ASTM C355 ASTM C534 ASTM C552 ASTM C534 ASTM C591 IS 661
: Testing Methods for Insulating Materials. : Testing Methods for Insulating Materials thermal conductivity. : Testing Methods for Insulating Materials. : Preformed Flexible Elastomeric Cellular Thermal Insulation. : Cellular Glass Thermal Insulation. : Un-faced Preformed Rigid Cellular Polyurethane Thermal Insulation. : Insulation Material and its application. : Testing Methods for Insulating Materials. IS 702 : Insulation Ancillary Material and its application. IS 1322 : Insulation Ancillary Material and its application. IS 4671 : Standard Specification for Insulation Material and its application.
16.2 Properties of Thermal Insulation The insulation Materials should be inflammable and self-extinguishing type and non-corrosive to the surface of insulation, chemically inert, moisture free, rot and vermin proof such as expanded Polystyrene foam prepared from styrene homo-polymer or copolymer containing an expanding agent, rigid Polyurethane foam, mattresses of resin bonded Mineral Wool or Glass Wool. The insulating materials should not disintegrate, settle, and change its form of composition in the detrimental service conditions. The water vapour permeance of the insulating materials should not be more than 0.4 gm/m2 /per day/ mm of Hg as per IS 661 or 3 per inch as per ASTM C355, desiccant method. The thermal conductivity of the insulating materials varies with the density of slab, thickness of the slab, the temperature gradient, and the time. The insulation Materials should be free from leachable chlorides. Durability of insulation materials is a very important environmental consideration. Ancillary of Insulation Installation: The following ancillary Insulating Materials are widely used in industrial insulation work: Wire Netting of 24 SWG x 20 mm mesh size, galvanized to secure the insulating material. The lacing and stitching wire of 20 SWG, galvanized to secure the wire net. The Band Aluminium strip of 20 mm width and 14 SWG. The Adhesive material for Polyurethane (Foster Fire Resistive Adhesive), type 81-83 or Blown Bitumen, type 85/25. The Adhesive material for Polystyrene and Mineral Wool (Blown Bitumen), type 85/25 conforming to IS 702. The Vapour Seal or Vapour Barrier for Polyurethane (Foster Fire Retardant Mastic), type 60-30 or Bitumen Emulsion Mastic, “Insulkote”, grade T-12 or equivalent Material. The Vapour Seal or vapour barrier for Polystyrene and Mineral Wool (Bitumen Emulsion Mastic) “Insulkote”, grade T-12 or Equivalent Materials. The Filler Materials for Polyurethane (Polyurethane Foam Dust) or Mineral Wool mixed with specified adhesive, packed tightly so that it can fill all the irregular voids and all contraction joints. The Filler Materials for Polystyrene (Polystyrene beads mixed with Blown Bitumen), packed tightly so that it can fill all the irregular voids and all contraction joints. The Filler Materials for Mineral Wool (loose Mineral Wool), packed tightly so that it can fill all the irregular voids and all contraction joints. The Joint Sealer material to seal the insulation work joints and at flashing of Polyurethane insulation work (Foster Foam Sealer), type 30-45. The Joint Sealer material to seal the insulation work joints and at flashing of Polystyrene and mineral wool insulation work (Blown Bitumen), type 85/25 conforming to IS 702. The glass Cloth used for vapour barrier reinforcement should be open weave of 10 mesh glass cloth having glass fibre thickness of 5 mils. The Anticorrosive paint single pack, air drying, water resistant, Phenol Resin Medium Pigmented with Zinc Chromate Red Oxide. It should be applied with brush, should get dried up in 4 – 5 hours, and should provide 25 microns thickness. The Bituminized Self-Finishing Roofing felt conforming to IS 1322, type 3, grade 1. The Aluminium Sheet for cladding the insulation work over the vapour barrier shall be as below: Size of Insulation
Thickness of Aluminium Sheet
Up to 500 mm nominal diameter -------------------Above 500 mm nominal diameter ------------------Over valve, flange joints and removable area --------
26 SWG 24 SWG 22 SWG
Effect of Thermal Insulation; Thermal insulation provides a means to maintain a gradient of temperature, by providing a region of insulation in which heat flow is reduced or thermal radiation is reflected rather than absorbed. Thermal conductivity (K), density and specific heat (C) are the main factors, which influence insulation efficiency. Process piping often has to be insulated against potential heat loss under conditions of the process requirement, protection from freezing the fluid, or protection of personnel from hot piping burning. Thermal Insulation for piping Systems is used for engineering reasons. The Insulation Specification provides guidance on insulation thickness based on pipe size, insulation thermal conductivity or material, and range of temperature service. Site engineer coordinates with the process piping specification and contract drawings while executing the Insulation work. Insulation Material shall have flexibility, flame resistance, abrasion resistance, and water and oil resistance. Product features include molten splash resistance and resistance to water, moisture, and hydraulic oils at high temperatures. Pipe Insulation is thermal or acoustic insulation used on pipe work. Insulation of pipes using pipe insulation reduces energy and prevents pipe freezing and condensation from occurring on cold and chilled pipe work. a) Process Control Insulation: The piping, which requires insulation are indicated in the piping line schedule and data sheets of the equipment/ vessels/ heat exchanger etc are to be insulated. However, the Bonnet of the Valve above the packing glands, Name Plates, Stamping, and the Code Inspection Plated on the Vessels and Equipment should not be insulated at all. b) Condensation control: When pipes operate at below-ambient temperatures, there is potential for water vapour to condense on the pipe surface, which contributes pipe corrosion. Pipe Insulation prevents the formation of condensation on pipe work, which is considered important. c) Pipe freezing: When water pipes are located in cold area, where the ambient temperature may occasionally drop below the freezing point of water, then any water in the pipe work may potentially freeze. When water freezes, it expands due to negative thermal expansion, and this expansion can cause failure of a pipe system and also stop the piping operation. Pipe insulation can prevent the freezing of water in pipe work and reduces the risk of the water in the pipes freezing. A smaller-bore pipe holds a smaller volume of water than a larger-bore pipe, and therefore water in a smaller-bore pipe will freeze more easily and more quickly than water in a larger-bore pipe. d) Energy saving: When pipe work operates at high temperatures, the rate of heat flow from a high temperature pipe is related to the temperature differential between the pipe and the surrounding ambient air and so the heat flow from pipe work is considerable. In many situations, this heat flow is undesirable. The application of thermal pipe insulation introduces thermal resistance and reduces the heat flow. e) Personnel Safety: When pipe work is operating at extremely high or low temperatures, the potential exists for personnel injury to occur should any person come into physical contact with the pipe surface. The International standards have set recommended touch temperature limits. Pipe insulation has a "less extreme" temperature, where surface touch temperatures is in a safe range. In any industry, the operators or the officers move around in the plant to operate the different valves and also for maintenance of the plant during breakdown. At the same time, there are many steam lines or the heated process pipe around the operating platform or the surrounding area. Most of the time there
is maximum chance of skin burn due touching to the hot pipe. As a safety precaution, the insulation of the pipe has to be done. This type of insulation is called Personnel Safety Insulation. Thermal insulation should be used on plant piping for personnel protection, prevention of moisture or ice on piping too. For personnel protection, all readily accessible surfaces operating above 160 0F should be insulated. Surfaces with a temperature in excess of 400 0F should be protected from liquid hydrocarbon spillage and surfaces in excess of 900 0F should be protected from combustible gasses. (f) Control of noise: Pipe work can operate as a conduit for noise to travel from one part to another part. Acoustic insulation can prevent this noise transfer by acting to damp the pipe wall and performing an acoustic decoupling function wherever the pipe passes through a fixed wall or floor and wherever the pipe is mechanically fixed. Pipe work can also radiate mechanical noise. In such circumstances, the breakout of noise from the pipe wall is achieved by acoustic insulation incorporating a high-density sound barrier. Pipe Insulation is thermal or acoustic insulation used on pipe work. Factors affecting selection of insulation Materials: Insulation performance is influenced by many factors, such as; Thermal Conductivity ("k" or "λ" value); Surface Emissivity ("ε" value); Insulation Thickness; Density; Specific Heat Capacity and Thermal bridging. It is important to note that the factors influencing performance may vary over time as material ages or environmental conditions change. Thermal conductivity: Thermal Conductivity, k, is the property of a material's ability to conduct heat. Heat transfer across materials of high thermal conductivity occurs at a faster rate than across materials of low thermal conductivity. Correspondingly materials of low thermal conductivity are used as thermal insulation. Thermal conductivity of materials is temperature dependent. In general, materials become more conductive to heat as the average temperature increases. The reciprocal of thermal conductivity is Thermal Resistivity. This is a list of approximate values of thermal conductivity, k, for some common materials. Please consult the list of thermal conductivities for more accurate values, references and detailed information. Units of thermal conductivity: Thermal Conductivity is measured in watts per meter Kelvin (W/(m·K)) in the International System of Units (SI). In the imperial system of measurement, Thermal Conductivity is measured in Btu/(hr·ft ⋅ F) where 1 Btu/(hr·ft ⋅ F) = 1.730735 W/(m·K). The construction industry makes use of units such as the R-Value (Resistance Value) and the U-Value (Thermal Transmittance Value). R and U-values are dependent on the thickness of a product. Thermal Conductance: Thermal Conductance is the quantity of heat that passes in unit time through a plate of particular area and thickness with a temperature difference of one Kelvin. With the thermal conductivity k, area A and thickness L, Thermal Conductance is kA/L, which is measured in W·K−1 = W/°C. Heat Transfer Coefficient: The quantity of heat that passes in unit time through unit area and a particular thickness with a temperature difference by one Kelvin. The heat transfer coefficient is also known as Thermal Admittance. The reciprocal of Heat Transfer Coefficient is Thermal Insulance . Thermal Conductance = kA/L, measured in W·K−1 = W/ °C Thermal Resistance = L /(kA), measured in K·W−1 = °C/W Heat Transfer Coefficient = k/L, measured in W·K−1·m−2. Thermal Insulance = L /k, measured in K·m²·W−1.
Thermal Resistance: It is a thermal-property offered by a material to resist the flow of heat. Lesser the Thermal Resistance better will be the heat conduction and vice versa. Working in units of thermal resistance greatly simplifies the design calculation. The following formula can be used to estimate the performance:
Where: Rhs is the maximum Thermal Resistance of the material, in °C/W = K/W.; ΔT is the temperature difference (temperature drop), in °C; Pth is the thermal power (heat flow), in watts; Rs is the thermal resistance of the heat source, in °C/W . Thermal Transmittance: Thermal Transmittance incorporates the thermal conductance of a structure along with heat transfer due to convection and radiation. The influencing factors are: (i) Temperature: The effect of temperature on thermal conductivity is different for metals and nonmetals. In metals conductivity is primarily due to lattice vibrations and free electron, however, free electrons play a dominant role. Therefore any increase in temperature increases the lattice vibrations but affects the movement of free electrons adversely thereby decreasing the conductivity. Thermal Conductivity in non-metals is only due to lattice vibrations which increase with increasing temperature, and so the conductivity of non-metals increases with increasing temperature. Thermal Conductivity in Air and other gases is due to convection. Air and other gases are generally good insulators, in the absence of convection. Therefore, many insulating materials function simply by having a large number of gas-filled pockets which prevent large-scale convection. (ii) Emissivity: The Emissivity of a material (ε or e) is the relative ability of its surface to emit energy by radiation. It is the ratio of energy radiated by a particular material to energy radiated by a black body at the same temperature. A true black body would have a ε = 1 while any real object would have ε < 1. Emissivity is a dimensionless quantity. (iii) Density: The mass density or density of a material (ρ) is defined as its mass per unit volume. (iv) Heat capacity: Heat capacity or Thermal capacity (C), is the measurable physical quantity that characterizes the amount of heat required to change a substance's temperature by a given amount. In the International System of Units (SI), heat capacity is expressed in units of joule(s) (J) per Kelvin (K). An object's heat capacity (symbol C) is defined as the ratio of the amount of heat energy transferred to an object to the resulting increase in temperature of the object,
16.3
Theory of Heat Loss
Theory of Heat Loss: According to Newton’s Law of Cooling heat transfer rate is related to the instantaneous temperature difference between a hot and a cold media in a heat transfer process, the temperature difference vary with position and time Mean Temperature Difference: The determination of the mean temperature difference in a heat transfer process depends upon the direction of fluid flow involved in the process. With saturation of steam the primary fluid temperature can be taken as a constant because heat is transferred as a result of a change of phase only. The temperature profile in the primary fluid is not dependent on the direction of flow. When the secondary fluid passes over the heat transfer surface, the highest rate of heat transfer occurs at the inlet and progressively decays with higher secondary fluid temperature along its way to the outlet.
16.4
Theory of Heat Transfer
When a temperature gradient exists in solid, heat transfer take place as conduction. Energy is transferred from the more energetic to the less energetic molecules when neighbouring molecules collide. Conductive heat flow occurs in the direction of decreasing temperature because higher temperature is associated with higher molecular energy. The equation used to express heat transfer by conduction is known as Fourier’s Law and is expressed as: q = k A dT / s ----------------------------------------------------------------------
(4)
Where, q = heat transferred per unit time (W); A = heat transfer area (m²); K = thermal; Conductivity of Material (W/m.k or w/m. °C); dT = Temperature difference across the material (K or °C); and s = material thickness (m). The heat transfer rate through the insulation material depends on the thermal conductivity (k), also called the internal resistance of the material, the thickness of the insulating material layer applied on the pipe surface and the temperature of the hot pipe surface. Hence, the heat transfer varies directly to the thickness of the insulating layer and inversely to the thermal conductivity (k) of the insulating material. It is represented by the following equation: H = UA (t1 – t2) 1 U= x/ k+1/ f
---------------------------------------------------
(5)
------------------------------------------------------------
(6)
Where, H = total heat transfer, Btu/hr.; A = area of pipe surface, sq. ft.; t1 = temperature of hot pipe surface, 0 F; and t2 = temperature of surrounding air, 0 F. The area of the path through which the heat transfer takes place is different on the flat surface, the outside area of flat surface being the same as the inside area, as compared to the curved (pipe) surface. On cylindrical surface, the area of the internal surface of the pipe is less for a given out side area of the pipe. But, in normal case, for all practical purposes, we consider or measure the outside surface area of the pipe for calculation of heat transfer. The third formulae for the heat transfer through insulation on a flat surface can be calculated by the following formula too: Q q= A (tp – ta) = (R + Rs)
------------------------------------------------------------------(7)
-------------------------------------------------------------------(8)
Where, q = Heat flux or quantity of heat transfer per unit area.; Q = Total heat transferred.; A = Total area of insulation.; tp = Process fluid temperature.; ta = Ambient temperature.; R = Thermal resistance
of the insulation.; and Rs = Thermal resistance of the insulation’s cladding material
16.5
Insulation Materials
Pipe insulation materials come in a large variety of forms, but most materials fall into one of the following categories: a) Hot Insulation: The hot insulation materials consist of Mineral fibre wool in the blanket of different thickness (2500F to 12000F), Flexible (4000F), Industrial bat (12000F), or Felt in blanket form or in loose form of different thickness (4000F); Calcium Silicate in the form of block and boards of different thickness (12000F); Asbestos (12000F), or Cement (12000F) of different thickness, Cellular Silica in the form of block of different thickness (16000F to 22000F), Diatomaceous Silica and 85% Magnesia (6000F). The above hot insulating materials are used for the hot pipe, the temperature varying from 2500F to 22000F. b) Cold Insulation: The cold as well as cryogenic insulation materials consist of Foam glass, Polyurethane, Mineral Wool, Polystyrene foam Magnesia, vermiculite and Perlite. Magnesia and Perlite powder is frequently used in cold box of cryogenic service insulation, such as air separation plant for manufacturing Oxygen, Nitrogen and Argon: Methane purification plant; low temperature gas treating plant. Air Krete: Air Krete (TM) is inorganic foam produced from magnesium oxide (derived from sea water). It is foamed under pressure with a microscopic cell generator and compressed air; no CFCs or HCFCs are used. Because of its inorganic composition, Air Krete has very low VOC emissions, is totally inert, and non-combustible. It is foamed in place in closed wall or masonry block cavities, or behind mesh in open cavities to form lightweight and rigid, but very friable, foam. Cellulose: Cellulose is perhaps the best insulation material out of recycled material use in insulation. Most cellulose insulation material is produced by approximately 80% post-consumer recycled newspaper by weight. The rest is comprised of fire retardant chemicals and, in some products, acrylic binders. The cellulose industry used approximately 450 million kg of recycled newspaper. Now, the cellulose insulation material is produced by new technologies. There is increasing use of lower-density cellulose produced by "fibre zing" process, because it results in a better product, cleaner, less dust, slightly higher R-value and, most important, because it stretches the resource base. The newspaper is breaking down into individual fibres that are fluffier. The industry is switching to this process from the older technologies known as “hammer mill” process. Cotton Insulation: Greenwood Cotton insulation is the new kid on the block in the fibre insulation industry. A small West Texas company using virgin cotton originally developed Cotton insulation as “Insulcot (TM)”. Promoted initially as a non-irritating alternative to fibreglass, early market research revealed an interest in use of recycled fibre, and the company switched to mill scraps from denim and T-shirt mills. The present product is approximately 95% post-industrial recycled fibre, 25% of which is polyester fibre. The polyester improves tear strength and recoil characteristics. The biggest concern with cotton insulation has been fire safety. The fire retardants for cellulose insulation were used in Insulcot, and different chemicals are used today, but he would not be more specific about the chemicals that are used. Expanded polystyrene: Expanded polystyrene (EPS) is the only common rigid foam board stock insulation made with neither CFCs nor HCFCs. During manufacture, polystyrene beads are expanded with pentane, a hydrocarbon that contributes to smog but is not implicated in ozone depletion or global warming; the pentane quickly leaks out of the insulation and is replaced by air. To meet strict air pollution standards in California, several EPS manufacturers have redesigned their plants to
recover up to 95% of the pentane used in production. And one of the largest polystyrene bead producers, BASF, has shifted to a low-pentane formulation. Fibreglass: Mainly, for the fibreglass insulation, at least 20% recycled glass cullet is used in insulation products to comply with the EPA recycled-content procurement guidelines. Fibreglass contains 25% recycled glass (18% post-consumer bottles and 7% post-industrial cullet). Recycled glass content in excess of 90% is feasible. Obtaining a consistent supply of quality, clear glass cullet has been a problem. Each percent of glass cullet (over 10%) substituted for raw sand reduces energy use by about 1%. The companies have plants using 40% recycled glass, but they claim a 20% average among all their plants. Most fibreglass insulation is produced using a phenol formaldehyde (PF) binder to hold the fibres together. Though exact quantities of binder used in manufacture of fibreglass are not known. A new type of fibreglass known as “Mira flex” (TM) that does not require a binder is being introduced in the market. Because there are no binders or other chemicals such as colorants in this product, pollution-control equipment is not required, and pollution emissions during manufacturing will be much less of a concern. Flexible Elastomeric Foams: Flexible elastomeric foams are flexible, closed-cell, rubber foams based on NBR or EPDM rubber. Flexible elastomeric foams exhibit such a high resistance to the passage of water vapour that they do not generally require additional water-vapour barriers. Such high vapour resistance, combined with the high surface emissivity of rubber, allows flexible elastomeric foams to prevent surface condensation formation with comparatively small thicknesses. As a result, flexible elastomeric foams are widely used on refrigeration and air-conditioning pipe work. Flexible elastomeric foams are also used on heating and hot-water systems. Glass Wool: Glass wool is a high-temperature fibrous insulation material, similar to mineral wool, where inorganic strands of glass fibre are bound together using a binder. As with other forms of mineral wool, glass-wool insulation can be used for thermal and acoustic applications. Icynene: Icynene (TM) is a product developed and introduced is introduced in the market. The foaming agent is a mixture of carbon dioxide and water. This eliminates polyurethane's HCFC-related environmental problems but also means a lower R-value. Like polyurethane, Icynene is foamed into wall cavities, but the resultant open-cell foam is soft, not rigid. In fact, it is marketed as much for its air sealing characteristics as its insulation properties. A recent development with Icynene is a second formulation that can be foamed into closed cavities. Mineral Wool: Mineral wool is a high-temperature insulation material and is the most common type of insulating materials. Its market share is large in the market. There are currently several manufacturers of mineral wool in India and in the U.S. "Mineral wool" actually refers to three different materials, such as (i) slag wool and (ii) rock wool and (iii) Slag Wools. Slag wool is produced primarily from iron ore blast furnace slag, an industrial waste product. Rock wool is produced from natural rocks, such as basalt and debase. Slag wool accounts for roughly 80% of the mineral wool industry, compared with 20% for rock wool. Given the relative use of these two materials, mineral wool has, on average, 75% post-industrial recycled content. According to the survey, over 500 million kg of blast furnace slag are used to produce slag wool. Mineral wools, including Rock wool and Slag Wools, are inorganic strands of mineral fibre bonded together using organic binders. Mineral wools are capable of operating at high temperatures and exhibit good fire performance ratings when tested. Mineral wools are used on all types of pipe work, particularly industrial pipe work operating at higher temperatures. Mineral wool Insulation, 1600 dpi scans with the grain. Perlite: It is used above -150 deg. F, for cryogenic storage tanks and cold box.
Polyethylene: Polyethylene is a semi-flexible plastic foamed insulation that is widely used to prevent freezing of domestic water supply pipes and to reduce heat loss from domestic heating pipes. The fire performance of Polyethylene usually prohibits its use in commercial buildings. The heat that the material can withstand is: Polyisocyanurate: The Polyisocyanurate foam insulation material uses recycled material in its products. EPA procurement guidelines call for a minimum 9% recycled content. Rather than using recycled foam, however, manufacturers buy polyol chemical components with recycled content. The industry is using some 15 million kg of recycled post-consumer chemicals. In addition to the raw chemicals having recycled content, the foil facings used on polyiso are typically 70-80% recycled aluminium. Polystyrene: Recycled plastic resin is used in manufacturing of some extruded and expanded polystyrene. Expanded polystyrene (EPS) can also be made out of recycled polystyrene. The simplest recycling involves crumbling the old EPS into small pieces and re-moulding them into usable shapes. Any polystyrene can be recycled into building insulation, but because of fire retardants, old building insulation cannot usually be recycled into non-building applications. Rigid Foam: Rigid foam is rigid Phenolic, PIR, or PUR foam insulation, which has minimal acoustic performance but can exhibit low thermal-conductivity values of 0.021 W/(m·K) or lower, allowing energy-saving legislation to be met whilst using reduced insulation thicknesses. Silica Aerogel: Silica Aerogel insulation has the lowest thermal conductivity of any commercially produced insulation. Although no manufacturer currently manufactures Aerogel pipe sections, it is possible to wrap Aerogel blanket around pipe work, allowing it to function as pipe insulation. The usage of Aerogel for pipe insulation is currently limited. Aerogels, micro porous silica and ceramic fibre insulation are three best performing insulators for applications between 200 Celsius and 2000 Celsius. Tri-Polymer Foam: Tri-Polymer Foam is a non-CFC, non-HCFC, and cavity-fill insulation used primarily in masonry block walls. It is essentially phenol foam and was developed as an alternative to urea formaldehyde foam insulation. It has very good fire resistance properties but does exhibit some shrinkage over time, which degrades its thermal performance. Water-Blown Polyurethane: Polyurethane insulation products that do not require HCFCs, but these materials have not yet been released to the building industry. They have both a closed-cell waterblown polyurethane (RT-2050) with an installed density of about 2 lbs/ft3 (32 kg/m3), and an opencell water-blown polyurethane with an installed density of .5-.8 lb/ft3 (8-12.8 kg/m3). The latter is probably quite similar to Icynene. Zirconium Fibres: Zirconium fibres have the lowest thermal conductivity of all ceramic fibre products and are used in applications up to 2000 Celsius. Material Mineral Wool/Glass wool Stone wool Ceramic fibre wool
Application Temperature 230 - 250 °C 700 - 850 °C 1200 °C Table: Thermal conductivity
Thermal
Thermal
Material
conductivity [W/(m·K)]
Material
conductivity [W/(m·K)]
Silica Aerogel
0.004 - 0.04
Air
0.025
Wood Hollow Fill Fibre Insulation Polypropylene Mineral oil Rubber Cement, Portland
0.04 - 0.4
Epoxy 0.12 - 0.177 (unfilled) Epoxy (silica0.30 filled) Thermal grease 0.7 - 3
0.042
Thermal epoxy
1-7
0.25 0.138 0.16
Glass Soil Concrete, stone
1.1 1.5 1.7
0.29
Sandstone
2.4
16.6
Application of Cold Insulation
Piping should be properly cleaned and primed prior to insulating. Some commonly used insulating materials are calcium silicate, mineral wool, glass fibre and cellular glass. A vapour barrier should be applied to the outer surface of the insulation on cold piping. Insulation should be protected by sheet metal jacketing from weather, oil spillage, mechanical wear, or other damage. If aluminium sheet metal is used for this purpose, an internal moisture barrier should protect it. To prevent H2 S from concentrating around the bolts, flanges should not be insulated in H2 S Service. Certain heating fluids are not compatible with some insulating materials and auto ignition may occur. Caution should be exercised in selecting materials. Certain insulation materials may be flammable. Surface Preparation: The surface of the pipe to be cold insulated should be cleaned in such a way that it is free from dust and loose paint and should be shot blasted, if required, before application of the primer. The primer coat of Phenolic Resin Medium Pigmented with Zinc Chromate Red Oxide should be applied on all the Carbon Steel and Alloy Steel surfaces before application of the cold insulating material. The Stainless Steel and other non-ferrous alloy surfaces should not be painted with the paint but should be wrapped with 0.1 mm Aluminium Foil with an overlap of minimum 50 mm having Barium Chromate Sealer interposed in the joint before application of the insulation on the surface. The Aluminium Foils should be secured in the position on the surface with the help of Aluminium Bands without making any pinhole or crack in the foils. Special care should be taken for the insulation of stainless steel pipe because of the possibility of Chloride Stress Cracking of the stainless steel pipe. After insulation, the material with a chloride content of very little amount as low as 0.05% by weight can cause the chloride concentration of 2% to 5% at the point of stress corrosion on the pipe surface because of the leaching out of chlorides in wet insulating material. To avoid the problem of chloride concentration on stainless steel pipe, Sodium Silicate should be used as insulation binder and as coating or 0.1 mm Aluminium Foil should be wrapped around before application of the insulation on the surface of stainless steel or non-ferrous alloy pipe before application of the insulation. Insulation Work: The insulation material such as radial lags or performed sections of the handling sizes and proper thickness and adhering to each other with applicable joint sealer as specified in the piping or equipment specification should be installed on the insulating surfaces as per the laid down and approved procedure. The insulating lags or sections should be secured on the surface in the position with the help of G.I. Wire Netting and Aluminium Bands at an interval of 250 mm to 300 mm. All the layers of the insulation should be secured with the help of Aluminium bands. The subsequent layers of insulation should be bonded to the preceding layers with the adhesive and the circumferential as well as the longitudinal joints should be staggered on each layer with reference to the preceding layers. Wire Netting: All the insulating layers, in case of higher thickness & multiplayer insulation, should be secured in the position on the metallic surface with the help of Aluminium Bands or Metallic Bands at the same interval of 250 to 300 mm before installation of the succeeding layer except the final layer. The Aluminium or the Metallic Bands should secure with G.I. Wire Netting and the final layer of the insulation at the same interval as above by staggering in lengthwise. The insulation should be stopped 250 mm away from the flange joint to allow their opening during the maintenance of the plant. Vapour Barrier: The 3.0 mm thick wet coating of Vapour Seal or Vapour Barrier, i.e. Foster Fire
Retardant Mastic, type 60-30 or Bitumen Emulsion Mastic, “Insulkote”, grade T-12 or equivalent Material should be applied over the insulation layer immediately after the completion of the insulation work to reduce the time of exposes of insulation material to the atmospheric weather conditions. Then, the Glass Cloth embedded in the Mastic should be laid wrinkle free, without air pocket and smooth over the vapour barrier. The second layer of 3.0 mm thick layer of the vapour barrier, i.e. mastic should be installed after sufficient time, i.e. after 12 hours approximately. While wrapping the glass cloth as vapour barrier, the care should be taken to provide a minimum 75 mm overlap at the edge of the glass cloth. The mastic coat thickness should not be more than 3.0 mm otherwise, it may develop a crack in the layer and at the same time, the dried film thickness of the mastic coat should not be less than 2.5 mm. Aluminium Cladding: The Aluminium Sheet, thickness as per the specification requirement, for cladding the insulation work over the completely dried vapour barrier, should be applied over the vapour barrier with a grooved joint and minimum overlap of 25 mm at the joint, with the sheet longitudinal joints suitably staggering and sealed with the Foster Foam Sealer, type 30-45 or Blown Bitumen, type 85/25 conforming to IS 702. The Self-Tapping screw should not be used to secure the Aluminium cladding as it can puncture the vapour barrier. Aluminium Band: The Aluminium Bands/ Clips should be used for cladding the insulation work over the Aluminium Cladding at the interval of 225 to 300 mm to secure the Aluminium Cladding. The Stainless Steel Bands/ Clips in place of Aluminium Bands should be used for cladding the insulation work in the corrosive environment where Sulphur Dioxide or other corrosive media is likely to be present. Expansion/Contraction Joints: The contraction/expansion joints with a gap of 12 mm and to a depth of 6 mm less than the adjacent thickness of the insulation,, loosely packed with filler insulating material as per specification at an suitable of 4.0 to 6.0 meter on pipe line or specified intervals, should be provided on the pipeline or the vessels, if necessary to allow the movement, i.e. expansion or contraction on the pipe surface without producing any crack in the insulation layer. The balance 6.0 mm gap of the expansion/contraction joints should be filled with an approve non-setting compound such as Foster Foam Seal 30-45 sealer or equivalent materials and should be flash finished with the surface of insulation.
16.7
Application of Hot Insulation
The insulation of the steel surface above 800C is considered as hot Insulation. For the pipe temperature 6000F and above, the double layer of hot insulation, with overlapping on the construction joint of insulation, is recommended because of the considerable expansion of the pipe at 6000F to 22000F and the single layer of insulation will crack and deteriorate. Insulation Work: The insulation material such as Slag Wool or Glass wool or performed sections of the handling sizes and proper thickness as specified in the piping or equipment specification should be installed on the insulating surfaces as per the laid down and approved procedure. The insulating lags or sections should be secured on the surface in the position with the help of G.I. Wire Netting and Aluminium Bands at an interval of 250 mm to 300 mm. All the layers of the insulation should be secured with the help of Aluminium bands. The subsequent layers of insulation should be bonded to the preceding layers with the adhesive and the circumferential as well as the longitudinal joints should be staggered on each layer with reference to the preceding layers. Wire Netting: All the insulating layers, in case of higher thickness & multiplayer insulation, should be secured in the position on the metallic surface with the help of Aluminium Bands or Metallic Bands at the same interval of 250 to 300 mm before installation of the succeeding layer except the final layer. The Aluminium or the Metallic Bands should secure with G.I. Wire Netting and the final layer of the insulation at the same interval as above by staggering in lengthwise. The insulation should be stopped 250 mm away from the flange joint to allow their opening during the maintenance of the plant. Aluminium Cladding: The Aluminium Sheet, thickness as per the specification requirement, for cladding the insulation work over the completed insulation, should be applied with a grooved joint and minimum overlap of 25 mm at the joint, with the sheet longitudinal joints suitably staggered. The Self-Tapping screw should be used to secure the Aluminium cladding. Aluminium Band: The Aluminium Bands/ Clips should be used for cladding the insulation work over the Aluminium Cladding at the interval of 225 to 300 mm to secure the Aluminium Cladding. The Stainless Steel Bands/ Clips in place of Aluminium Bands should be used for cladding the insulation work in the corrosive environment where Sulphur Dioxide or other corrosive media is likely to be present. Expansion/Contraction Joints: The contraction/expansion joints with a gap of 12 mm and to a depth of 6 mm less than the adjacent thickness of the insulation,, loosely packed with filler insulating material as per specification at an suitable of 4.0 to 6.0 meter on pipe line or specified intervals, should be provided on the pipeline or the vessels, if necessary to allow the movement, i.e. expansion or contraction on the pipe surface without producing any crack in the insulation layer. The balance 6.0 mm gap of the expansion/contraction joints should be filled with approved equivalent materials and should be flash finished with the surface of insulation.
16.8
Insulation Inspection
The sample of the insulating materials should be sent in the approved laboratory for the testing before application on the pipe. The test result should be compared with the properties of the insulation material to conform the specification requirements. The thickness of the ready-made mat should be checked by a standard engineering method. The continuous vigilance and visual inspection shall be carried out for the correct installation of the insulation.
17 Non-Metallic Piping 17.1
Plastic Piping Systems
Thermoplastic piping systems, commonly referred to as plastic piping systems, are composed of various additives to a base resin or composition. Thermoplastics are characterized by their ability to be softened and reshaped repeatedly by the application of heat. Following is the list and the chemical names and abbreviations for a number of plastic piping materials. Properties of plastic piping materials, such as, polyvinyl chloride-PVC, may vary from manufacturer to manufacturer because of the slightly different formulations. Therefore, designs and specifications need to consider specific material requirements on a type or grade basis as mentioned below: a. Deterioration of Plastic Piping: Unlike metallic piping, thermoplastic materials do not display corrosion rates. That is, the deterioration of thermoplastic materials, which is dependent totally on the material’s chemical resistance rather than an oxide layer. So the material is either completely resistant to a chemical or it deteriorates. Plastic piping system corrosion is indicated by material softening, discoloration, charring, embrittlement, stress cracking, blistering, swelling, dissolving, and other effects. Corrosion of plastics occurs by the following mechanisms: - Absorption; - Salvation; - Chemical reactions such as oxidation (affects chemical bonds), hydrolysis (affects ester linkages), radiation, dehydration, alkylation, reduction, and halogenations (chlorination); - Thermal degradation, which may result in either depolymerization or plasticization; - Environmental-stress cracking (ESC) which is essentially the same as stress-corrosion cracking in metals; - UV degradation; and - Combinations of the above mechanisms. If reinforcing is used as part of the piping system, the reinforcement is also a material that is resistant to the fluid being transported. Material selection and compatibility review should consider the type and concentration of chemicals in the liquid, liquid temperature, duration of contact, total stress of the piping system, and the contact surface quality of the piping system. b. Operating Pressures and Temperatures: The determination of maximum steady state design pressure and temperature is similar to that described for metallic piping systems. However, a key issue that must be addressed relative to plastic piping systems is the impact of both minimum and maximum temperature limits of the materials of construction. c. Sizing: The sizing for plastic piping systems is performed consistent with the procedures of
metallic piping systems. However, one of the basic principles of designing and specifying thermoplastic piping systems for liquid process piping pressure applications is that the short and long term strength of thermoplastic pipe decreases as the temperature of the pipe material increases and its deterioration. Thermoplastic pipe is pressure rated by using the International Standards Organization (ISO) rating equation using the Hydrostatic Design Basis (HDB) as contained in ASTM standards and Design Factors (DFs). The use of DFs is based on the specific material being used and specific application requirements such as temperature and pressure surges The minimum pipe wall thickness can also be determined using the requirements of ASME B31.3 as described in Paragraph Design. This procedure is not directly applicable to thermoplastic pipe fittings, particularly in cyclic pressure operations due to material fatigue. Therefore, it should not be assumed that thermoplastic fittings labelled with a pipe schedule designation would have the same pressure rating as pipe of the same designation. A good example of this is contained in ASTM D 2466 and D 2467, which specify pressure ratings for PVC schedule 40 and 80 fittings. These ratings are significantly lower than the rating for PVC pipe of the same designation. For thermoplastic pipe fittings that do not have published pressure ratings information similar to ASTM standards, the fitting manufacturer shall be consulted for fitting pressure-rating recommendations. d. Joining: Common methods for the joining of thermoplastic pipe for liquid process waste treatment and storage systems are contained in following table. In selecting a joining method for liquid process piping systems, the advantages and disadvantages of each method are evaluated and the manner by which the joining is accomplished for each liquid service is specified. Recommended procedures and specification for these joining methods are found in codes, standards, and manufacturer procedures for joining thermoplastic pipe. Following lists the applicable references for joining thermoplastic pipe. Table: Thermoplastic Joining Methods Joining Method ABS PVC CPVC PE PP PVDF Solvent X X X Cementing Heat Fusion X X X Threading * X X X X X X Flanged X X X X X X Connectors ** Grooved Joints X X X X X X *** Mechanical X X X X X X Compression **** Elastomeric seal X X X X X X Flaring X Notes: X = applicable method; Threading requires a minimum pipe wall thickness (Schedule 80); Flanged adapters are fastened to pipe by heat fusion, solvent, cementing, or threading; Grooving requires a minimum pipe wall thickness (material dependent) and Internal stiffeners are required.
Table: Thermoplastic Joining Standards Reference ASTM 2657 ASTM 2855 ASTM 3139 ASTM 1290
Key Aspects of Reference D Recommended practice for heat fusion. D Standard practice for solvent cementing PVC pipe and fittings. D Elastomeric gasket connections for pressure applications. F Recommended practice for electro fusion.
e. Thermal Expansion: When designing a piping system where thermal expansion of the piping is restrained at supports, anchors, equipment nozzles and penetrations, large thermal stresses, and loads must be analyzed and accounted for within the design. The system PFDs and P&IDs are analyzed to determine the thermal conditions or modes to which the piping system will be subjected during operation. Based on this analysis, the design and material specification requirements from an applicable standard or design reference are followed in the design. A basic approach to assess the need for additional thermal stress analysis for piping systems includes identifying operating conditions that will expose the piping to the most severe thermal loading conditions. Once these conditions have been established, a free or unrestrained thermal analysis of the piping can be performed to establish location, sizing, and arrangement of expansion loops, or expansion joints, generally, bellows or slip types. f. Piping Support and Burial: Support for thermoplastic pipe follows the same basic principles as metallic piping. Spacing of supports is crucial for plastic pipe. Plastic pipe will deflect under load more than metallic pipe. Excessive deflection will lead to structural failure. Therefore, spacing for plastic pipe is closer than for metallic pipe. Valves, meters, and fittings should be supported independently in plastic pipe systems, as in metallic systems. In addition, plastic pipe systems are not located near sources of excessive heat. The nature of thermoplastic pipe is that it is capable of being repeatedly softened by increasing temperature, and hardened by decreasing temperature. If the pipe is exposed to higher than design value ambient temperatures, the integrity of the system could be compromised. Contact with supports should be such that the plastic pipe material is not damaged or excessively stressed. Point contact or sharp surfaces are avoided as they may impose excessive stress on the pipe or otherwise damage it. Support hangers are designed to minimize stress concentrations in plastic pipe systems. Spacing of supports should be such that clusters of fittings or concentrated loads are adequately supported. Valves, meters, and other miscellaneous fittings should be supported exclusive of pipe sections. Supports for plastic pipe and various valves, meters, and fittings, should allow for axial movement caused by thermal expansion and contraction. In addition, external stresses should not be transferred to the pipe system through the support members. Supports should allow for axial movement, but not lateral movement. When a pipeline changes direction, such as through a 90E elbow, the plastic pipe should be rigidly anchored near the elbow.
Plastic pipe systems should be isolated from sources of vibration, such as pumps and motors. Vibrations can negatively influence the integrity of the piping system, particularly at joints. Support spacing for several types of plastic pipe are found in following Tables. Spacing is dependent upon the temperature of the fluid being carried by the pipe. The determining factor to consider in designing buried thermoplastic piping is the maximum allowable deflection in the pipe. The deflection is a function of the bedding conditions and the load on the pipe. Proper excavation, placement, and backfill of buried plastic pipe are crucial to the structural integrity of the system. It is also the riskiest operation, as a leak in the system may not be detected before contamination has occurred. A proper bed, or trench, for the pipe is the initial step in the process. In cold weather areas, underground pipelines should be placed no less than one foot below the frost line. The trench bottom should be relatively flat, and smooth, with no sharp rocks that could damage the pipe material. The pipe should be bedded with a uniformly graded material that will protect the pipe during backfill. Typical installations use an American Association of State Highway Transportation Officials (AASHTO) aggregate, or pea-gravel for six inches below and above the pipe. These materials can be dumped in the trench at approximately 90-95% Proctor without mechanical compaction. The remainder of the trench should be backfilled with earth, or other material appropriate for surface construction, and compacted according to the design specifications. Table: Support Spacing for Schedule 80 PVC Pipe Nominal Pipe Size, mm (in)
25 (1) 40 (1.5) 50 (2) 80 (3) 100 (4) 150 (6)
Maximum Support Spacing, m (ft) at Various Temperatures 16C (60F) 16C (60F) 38C (100F)
49C (120F)
60C (140F)*
1.83 (6.0) 1.68 (5.5) 1.52 (5.0) 1.07 (3.5) 0.91 (3.0) 1.98 (6.5) 1.83 (6.0) 1.68 (5.5) 1.07 (3.5) 1.07 (3.5) 2.13 (7.0) 1.98 (6.5) 1.83 (6.0) 1.22 (4.0) 1.07 (3.5) 2.44 (8.0) 2.29 (7.5) 2.13 (7.0) 1.37 (4.5) 1.22 (4.0) 2.74 (9.0) 2.59 (8.5) 2.29 (7.5) 1.52 (5.0) 1.37 (4.5) 3.05 2.90 (9.5) 2.74 (9.0) 1.83 (6.0) 1.52 (5.0) (10.0) 200 (8) 3.35 3.2 (10.5) 2.90 (9.5) 1.98 (6.5) 1.68 (5.5) (11.0) 250 (10) 3.66 3.35 3.05 2.13 (7.0) 1.83 (6.0) (12.0) (11.0) (10.0) 300 (12) 3.96 3.66 3.2 (10.5) 2.29 (7.5) 1.98 (6.5) (13.0) (12.0) 350 (14) 4.11 3.96 3.35 2.44 (8.0) 2.13 (7.0) (13.5) (13.0) (11.0) Note: The above spacing values are based on test data developed by the manufacturer for the specific product and continuous spans. The piping
is insulated and is full of liquid that has a specific gravity of 1.0.; The use of continuous supports or a change of material (e.g., to CPVC) is recommended at 60EC (140EF). Source: Harvel Plastics, Product Bulletin Table: Support Spacing for Schedule 80 PVDF Pipe Nominal Maximum Support Spacing, m (ft) at Various Pipe Temperatures Size, mm (in) 20C (68F) 40C (104F) 60C (140F) 80C (176F) 25 (1) 1.07 (3.5) 0.91 (3.0) 0.91 (3.0) 0.76 (2.5) 40 (1.5) 1.22 (4.0) 0.91 (3.0) 0.91 (3.0) 0.91 (3.0) 50 (2) 1.37 (4.5) 1.22 (4.0) 0.91 (3.0) 0.91 (3.0) 80 (3) 1.68 (5.5) 1.22 (4.0) 1.22 (4.0) 1.07 (3.5) 100 (4) 1.83 (6.0) 1.52 (5.0) 1.22 (4.0) 1.22 (4.0) 150 (6) 2.13 (7.0) 1.83 (6.0) 1.52 (5.0) 1.37 (4.5) Note: The above spacing values are based on test data developed by the manufacturer for the specific product and continuous spans. The piping is insulated and is full of liquid that has a specific gravity of 1.0. Source: Asahi/America, Piping Systems Product Bullet
Table: Support Spacing for Schedule 80 PVDF Pipe Nominal Maximum Support Spacing, m (ft) at Various Pipe Temperatures Size, 23C 38C 49C 60C 71C 82C mm (in) (73F) (100F) (120F) (140F) (160F) (180F) 25 (1) 40 (1.5) 50 (2) 80 (3) 100 (4) 150 (6) 200 (8)
1.83 (6.0) 2.13 (7.0) 2.13 (7.0) 2.44 (8.0) 2 59 (8.5) 3.05 (10.0) 3.35
1.83 1.68 1.52 (6.0) (5.5) (5.0) 1.98 1.83 1.68 (6.5) (6.0) (5.5) 2.13 1.98 1.83 (7.0) (6.5) (6.0) 2.44 2.29 2.13 (8.0) (7.5) (7.0) 2 59 2 59 2.29 (8.5) (8.5) (7.5) 2.90 2.74 2.44 (9.5) (9.0) (8.0) 3.20 3.05 2.74
1.07 (3.5) 1.07 (3.5) 1.22 (4.0) 1.37 (4.5) 1.52 (5.0) 1.68 (5.5) 1.83
0.91 (3.0) 0.91 (3.0) 1.07 (3.5) 1.22 (4.0) 1.37 (4.5) 1.52 (5.0) 1.68
(11.0) (10.5) (10.0) (9.0) (6.0) (5.5) 250 (10) 3.51 3.35 3.20 2.90 1.98 1.83 (11.5) (11.0) (10.5) (9.5) (6.5) (6.0) 300 (12) 3.81 3.66 3.51 3.20 2.29 1.98 (12.5) (12.0) (11.5) (10.5) (7.5) (6.5) Note: The above spacing values are based on test data developed by the manufacturer for the specific product and continuous spans. The piping is insulated and is full of liquid that has a specific gravity of 1.0. Source: Harvel Plastics, Product Bulletin Polyvinyl Chloride (PVC) Piping Polyvinyl chloride (PVC) is the most widely used thermoplastic piping system. PVC is stronger and more rigid than the other thermoplastic materials. When specifying PVC thermoplastic piping systems particular attention must be paid to the high coefficient of expansion-contraction for these materials in addition to effects of temperature extremes on pressure rating, visco-elasticity, tensile creep, ductility, and brittleness. a. PVC Specifications PVC pipe is available in sizes ranging from 8 to 400 mm (1/4 to 16 in), in Schedules 40 and 80. Piping shall conform to ASTM D 2464 for Schedule 80 threaded type; ASTM D 2466 for Schedule 40 socket type; or ASTM D 2467 for Schedule 80 socket type. Maximum allowable pressure ratings decrease with increasing diameter size. To maintain pressures ratings at standard temperatures, PVC is also available in Standard Dimension Ratio (SDR). SDR changes the dimensions of the piping in order to maintain the maximum allowable pressure rating. b. PVC Installation For piping larger than 100 mm (4 in) in diameter, threaded fittings should not be used. Instead socket welded or flanged fittings should be specified. If a threaded PVC piping system is used, two choices are available, either uses all Schedule 80 piping and fittings, or use Schedule 40 pipe and Schedule 80 threaded fittings. Schedule 40 pipe will not be threaded. Schedule 80 pipe would be specified typically for larger diameter pipes, elevated temperatures, or longer support span spacing. The system is selected based upon the application and design calculations. The ranking of PVC piping systems from highest to lowest maximum operating pressure is as follows: Schedule 80 pipe socketwelded; Schedule 40 pipe with Schedule 80 fittings, socket-welded; and Schedule 80 pipe threaded. Schedule 40 pipes provide equal pressure rating to thread Schedule 80, making Schedule 80 threaded uneconomical. In addition, the maximum allowable working pressure of PVC valves is lower than a Schedule 80 threaded piping system. Polytetrafluoroethylene (PTFE) Piping Polytetrafluoroethylene (PTFE) is a very common thermoplastic material used in many other applications in addition to piping systems. PTFE is chemically resistant and has a relatively wide allowable temperature range of -260EC (-436EF) to 260EC (500EF). Furthermore, PTFE has a high impact resistance and a low coefficient of friction and is often considered “self-lubricating”. The most common trade name for PTFE is Teflon, registered trademark of E.I Dupont Company. Acrylonitrile-Butadiene-Styrene (ABS) Piping Acrylonitrile-Butadiene-Styrene (ABS) is a thermoplastic material made with virgin ABS compounds meeting the ASTM requirements of Cell Classification 4-2-2-2-2 (pipe) and 3-2-2-2-2 (fittings). Pipe
is available in both solid wall and cellular core wall. Pipe and fittings are available in size 32 mm (1-1/4 in) through 300 mm (12 in) in diameter. The pipe can be installed above or below grade. a. ABS Standards ASTM D 2282 specifies requirements for solid wall ABS pipe. ASTM D 2661 specifies requirements for solid wall pipe for drain, waste, and vents. ASTM F 628 specifies requirements for drain, waste, and vent pipe and fittings with a cellular core. Solid wall ABS fittings conform to ASTM D 2661. ASTM D 3311 specifies the drainage pattern for fittings. ABS compounds have many different formulations that vary by manufacturer. The properties of the different formulations also vary extensively. ABS shall be specified very carefully and thoroughly because the acceptable use of one compound does not mean that all ABS piping systems are acceptable. Similarly, ABS compositions that are designed for air or gas handling may not be acceptable for liquids handling. b. ABS Limitations Pigments are added to the ABS to make pipe and fittings resistant to ultraviolet (UV) radiation degradation. Pipe and fittings specified for buried installations may be exposed to sunlight during construction, however, and prolonged exposure is not advised. ABS pipe and fittings are combustible materials; however, they may be installed in non-combustible buildings. Most building codes have determined that ABS must be protected at penetrations of walls, floors, ceilings, and fire resistance rated assemblies. The method of protecting the pipe penetration is using a through-penetration protection assembly that has been tested and rated in accordance with ASTM E 814. The important rating is the "F" rating for the through penetration protection assembly. The "F" rating must be a minimum of the hourly rating of the fire resistance rated assembly that the ABS plastic pipe penetrates. Local code interpretations related to through penetrations are verified with the jurisdiction having authority. Chlorinated Polyvinyl Chloride (CPVC) Piping Chlorinated polyvinyl chloride (CPVC) is more highly chlorinated than PVC. CPVC is commonly used for chemical or corrosive services and hot water above 60EC (140EF) and up to 99EC (210EF). CPVC is commercially available in sizes of 8 to 300 mm (1/4 to 12 in) for Schedule 40 and Schedule 80. Exposed CPVC piping should not be pneumatically tested, at any pressure, due to the possibility of personal injury from fragments in the event of pipe failure; see Paragraph 3-8d for further information. ASTM specifications for CPVC include: ASTM F 437 for Schedule 80 threaded type; ASTM F 439 for Schedule 80 socket type; and ASTM F 438 for Schedule 40 socket type. However, note that Schedule 40 socket may be difficult to procure. Polyethylene (PE) Piping Polyethylene (PE) piping material properties vary with manufacturing processes. Table 5-10 lists the common types of PE, although an ultra high molecular weight type also exists. PE should be protected from ultraviolet radiation by the addition of carbon black as a stabilizer; other types of stabilizers do not protect adequately. PE piping systems are available in sizes ranging from 15 to 750 mm (½ to 30 in). Like PVC, PE piping is available in SDR dimensions to maintain maximum allowable pressure ratings. Polypropylene (PP) Piping Polypropylene (PP) piping materials are similar to PE, containing no chlorine or fluorine. PP piping systems are available in Schedule 40, Schedule 80, and SDR dimensions. With a specific gravity of 0.91, PP piping systems are one of the lightest thermoplastic piping systems. Polyvinylidene Fluoride (PVDF) Piping Polyvinylidene fluoride (PVDF) pipe is available in a diameter range of 15 to 150 mm (½ to 6 in);
Schedules 40 and 80; and pressure ratings of 1.03 MPa (150 psig) and 1.59 MPa (230 psig). Use of PVDF with liquids above 490C (1200F) requires continuous support. Care must be taken in using PVDF piping under suction. PVDF does not degrade in sunlight; therefore, PVDF does not require UV stabilizers or antioxidants. PVDF pipe is chemically resistant to most acids; bases and organics; and can transport liquid or powdered halogens such as chlorine or bromine. PVDF should not be used with strong alkalis, fuming acids, polar solvents, amines, ketones or esters. Trade names for PVDF pipe include Kynar by Elf Atochem, Solef by Solvay, Hylar by Ausimont USA, and Super Pro 230 by Asahi America. Fusion welding is the preferred method for joining PVDF pipe. Threading can only be accomplished on Schedule 80 pipe. Table: Polyethylene Designations Type Low (LDPE) Medium (MDPE) High (HDPE)
Standard Density ASTM D 3350, Type I Density ASTM D 3350, Type II Density ASTM D 3350, Type III and ASTM D 1248 Type IV Source: Compiled by SAIC, 1998
Specific Gravity 0.91 to 0.925 0.926 to 0.940 0.941 to 0.959
17.2
Rubber and Elastomeric Piping
General The diverse nature of the chemical and physical characteristics of rubber and elastomeric materials makes these materials suited for many chemical handling and waste treatment applications. The most common elastomeric piping systems are comprised of hoses. These hoses are constructed of three components: the tube, the reinforcement, and the cover. The tube is most commonly an elastomeric and must be suitable for the chemical, temperature, and pressure conditions that a particular application involves. Following lists several elastomeric used in piping systems and the chemical identifications of the polymers. Physical and chemical characteristics of elastomeric used in hose manufacturing are specified in ASTM D 2000. Hose reinforcement is designed to provide protection from internal forces, external forces, or both. Reinforcement usually consists of a layer of textile, plastic, metal or a combination o f these materials. Hose covers are designed to provide hoses with protection from negative impacts resulting from the environment in which the hose is used. Covers are also typically composed of textile, plastic, metal, or a combination of these materials. Design Factors In selecting and sizing a rubber or elastomeric piping system, four factors must be considered: service conditions, such as pressure and temperature; operating conditions, such as indoor/outdoor use, vibration resistance, intermittent of continuous service, etc); end connections; and environment requirements, such as flame resistance, material conductivity, labelling requirements, etc.. a. Service Conditions For applications requiring pressure or vacuum service reinforcement can improve the mechanical properties of the hose. The maximum recommended operating pressure in industrial applications utilizing Society of Automotive Engineers (SAE) standards hose designations is approximately 25% of the rated bursting pressure of the specific hose. Following are the lists of common SAE hose standards. In determining the maximum operating conditions, special consideration must be given to the operating temperatures. Rubber and elastomeric materials are temperature sensitive, and both the mechanical qualities and chemical resistance properties of the materials are affected by temperature. Table: Common Materials Used in Rubber/Elastomeric Piping Systems Elastomeric
Class ASTM D 1418
Common / Trade Name
Fluoroelastomer Isobutylene Isoprene Acrylonitrile Butadiene Polychloroprene
FKM
FKM, Viton, -230C (-100F) 2600C Fluorel (5000F) Butyl -460C (-500F) 1480C (3000F) Buna-N, -510C (-600F) 1480C Nitrile (3000F) Neoprene -400C (-400F) 1150C
IIR NBR CR
Minimum Maximum Service Service Temperature Temperature
Natural Rubber NR or Gum or SBR Rubber; Styrene Butadiene Source: Compiled by SAIC,
(2400F) -510C (-600F) 820C (1800F)
Table: Rubber and Elastomeric Hose Standards SAE Tube Designation 100R1A 100RIT 100R2A 100R2B 100R2AT 100R2BT 100R3 100R5 100R7 Thermoplastic 100R8 Thermoplastic 100R9 100R9T
Reinforcement
Cover
One-wire-braid One-wire-braid Two-wire-braid Two spiral wire plus one wire-braid Two-wire-braid Two spiral wire plus one wire-braid Two rayon-braided One textile braid plus one wire-braid Synthetic-fibre Synthetic-fibre Four-ply, light-spiralwire Four-ply, light-spiralwire
Syntheticrubber Thin, nonskive Synthetic rubber Synthetic rubber Thin, nonskive Thin, nonskive Synthetic rubber Textile braid Thermoplastic Thermoplastic Syntheticrubber Thin, nonskive
Source: Compiled by SAIC, As the operating temperature increases, the use of jacketed or reinforced hose should be considered to accommodate lower pressure ratings of the elastomeric materials. Like plastic piping systems, rubber and elastomeric systems do not display corrosion rates, as corrosion is totally dependent on the material's resistance to environmental factors rather than on the formation of an oxide layer. Material softening, discolouring, charring, embrittlement, stress cracking, blistering, swelling, and dissolving indicate the corrosion of rubbers and elastomeric. Corrosion of rubber and elastomeric occurs through one or more of the following mechanisms: absorption, salvation, chemical reactions, thermal degradation, and environmental stress cracking. General compatibility information for common elastomeric is listed in following table. In addition, standards for resistance to oil and
gasoline exposure have been developed by the Rubber Manufacturer’s Association (RMA). These standards are related to the effects of oil or gasoline exposure for 70 hours at 100 0C (ASTM D 471) on the physical/mechanical properties of the material. Table 6-4 summarizes the requirements of the RMA oil and gasoline resistance classes. b. Operating Conditions In most cases, the flexible nature of elastomeric will compensate for vibration and thermal expansion and contraction in extreme cases. However, designs should incorporate a sufficient length of hose to compensate for the mechanical effects of vibration and temperature. Table: General Chemical Compatibility Characteristics of Common Elastomeric Material Good Resistance Fluoroelastomer Oxidizing acids and oxidizers, fuels containing <30% aromatics Isobutylene Dilute mineral acids, Isoprene alkalis, some concentrated acids, oxygenated solvents Acrylonitrile Oils, water, and Butadiene solvents
Poor Resistance Aromatics; fuels containing >30% aromatics
Hydrocarbons and oils, most solvents, concentrated nitric and sulphuric acids Strong oxidizing agents, polar solvents, chlorinated hydrocarbons Polychloroprene Aliphatic solvents, Strong oxidizing acids, dilute mineral acids, chlorinated and salts, alkalis aromatic hydrocarbons Natural Rubber Non-oxidizing acids, Hydrocarbons, oils, or Styrene alkalis, and salts and oxidizing agents Butadiene Notes: See Appendix B for more chemical resistance information. Source: Compiled by SAIC,
Table: RMA Oil and Gasoline Resistance Classifications RMA Designation
Maximum Change Class A (High oil +25% resistance) Class B (Medium- +65% High oil resistance) Class C (Medium oil +100%
Volume Tensile Retained 80% 50% 40%
Strength
resistance) Source: RMA, "The Hose Handbook," c. End Connections Hose couplings are used to connect hoses to a process discharge or input point. Methods for joining elastomeric hose include banding/clamping, flanged joints, and threaded and mechanical coupling systems. These methods are typically divided into reusable and non - reusable couplings. Following lists common types of couplings for hoses. Selection of the proper coupling should take into account the operating conditions and procedures that will be employed. d. Environmental Requirements Hose is also manufactured with conductive, non - conductive, and uncontrolled electrical properties. Critical applications such as transferring aircraft hose or transferring liquids around high-voltage lines require the electrical properties of hose to be controlled. Unless the hose is designated as conducting or non-conducting, the electrical properties are uncontrolled. Standards do not currently exist for the prevention and safe dissipation of static charge from hoses. Methods used to control electrical properties include designing contact between a body reinforcing wire and a metal coupling to provide electrical continuity for the hose or using a conductive hose cover. ASTM D 380 describes standard test methods for the conductivity of elastomeric hoses. For a hose to be considered nonconductive, it should be tested using these methods. Sizing The primary considerations in determining the minimum acceptable diameter of any elastomeric hose is design flow rate and pressure drop. The design flow rate is based on system demands that are normally established in the process design phase of a project and which should be fully defined by this stage of the system design. Table: Typical Hose Couplings Class Reusable clamps
Description with 1. Short Shank Coupling 2. Long Shank Coupling 3. Interlocking Type 4. Compression Ring Type Reusable without 1. Screw Type clamps 2. Push-on Type Non-reusable 1. Swaged-on couplings 2. Crimped-on 3. Internally Expanded Full Flow Type 4. Built-in Fittings Specialty 1. Sand Blast Sleeves couplings 2. Radiator and Heater Clamps 3. Gasoline Pump Hose Couplings 4. Coaxial Gasoline Pump Couplings 5. Welding Hose Couplings 6. Fire Hose Couplings
Source: Compiled by SAIC.
Pressure drop through the elastomeric hose must be designed to provide an optimum balance between installed costs and operating costs. Primary factors that will impact these costs and system operating performance are internal diameter and the resulting fluid velocity, materials of construction and length of hose. Support and Burial Support for rubber and elastomeric-piping systems should follow similar principles as metallic and plastic pipe. However, continuous pi ping support is recommended for most applications due to the flexible nature of these materials. Also due to its flexible nature, elastomeric piping is not used in buried service because the piping is unable to support the loads required for buried service. When routing elastomeric hose, change in piping direction can be achieved through bending the hose rather than using fittings. When designing a rubber or elastomeric piping system, it is important to make sure that the bend radius used does not exceed the maximum bend radius for the hose used. If the maximum bend radius is exceeded, the hose may collapse and constricted flow or material failure could occur. As a rule of thumb, the bend radius should be six times the diameter of a hard wall hose or twelve times the diameter of a soft wall hose. Fluoroelastomer Fluoroelastomer (FKM) is a class of materials, which includes several fluoropolymers used for hose products. Trade names of these materials include Viton and Fluorel. Fluoroelastomers provide excellent high temperature resistance, with the maximum allowable operating temperatures for fluoroelastomer varying from 232 to 3150C (450 to 6000F), depending upon the manufacturer. Fluoroelastomers also provide very good chemical resistance to a wide variety of chemical classes. Sobutylene Isoprene Isobutylene isoprene (Butyl or II R) has excellent abrasion resistance and excellent flexing properties. These characteristics combine to give isobutylene isoprene very good weathering and aging resistance. Isobutylene isoprene is impermeable to most gases, but provides poor resistance to petroleum-based fluids. Isobutylene isoprene is also not flame resistant.
Acrylonitrile Butadiene Acrylonitrile butadiene (nitrile, Buna-N or NBR) offers excellent resistance to petroleum oils, aromatic hydrocarbons, and many acids. NBR also has good elongation properties. However, NBR does not provide good resistance to weathering. Polychloroprene Polychloroprene (neoprene or CR) is one of the oldest synthetic rubbers. It is a good all-purpose elastomeric that is resistant to ozone, ultraviolet radiation, and oxidation. Neoprene is also heat and flame resistant. These characteristics give neoprene excellent resistance to aging and weathering. Neoprene also provides good chemical resistance to many petroleum based products and aliphatic hydrocarbons. However, neoprene is vulnerable to chlorinated solvents, polar solvents, and strong mineral acids. Natural Rubber Natural rubber (styrene butadiene, gum rubber, Buna-S, NR, or SBR) has high resilience, good tear
resistance, and good tensile strength. I t also exhibits wear resistance and is flexible at low temperatures. These characteristics make natural rubber suitable for general service outdoor use. However, natural rubber is not flame resistant and does not provide resistance to petroleum-based fluids.
17.3
Thermoset Piping
Thermoset piping systems are composed of plastic materials and are identified by being permanently set cured or hardened into shape during the manufacturing process. Thermoset piping system materials are a combination of resins and reinforcing. The four primary Thermoset resins are epoxies, vinyl esters, polyesters, and furans. Other resins are available. a. Thermoset Piping Characteristics Advantages of Thermoset piping systems are a high strength-to-weight ratio; low installation costs; ease of repair and maintenance; hydraulic smoothness with a typical surface roughness of 0.005 mm (0.0002 in); flexibility, since low axial modulus of elasticity allows lightweight restraints and reduces the need for expansion loops; and low thermal and electrical conductivity. Disadvantages of thermo Set piping systems are low temperature limits; vulnerability to impact failure; increased support requirements, a drawback of the low modulus of elasticity; lack of dimensional standards including joints since pipe, fittings, joints and adhesives are generally not interchangeable between manufacturers; and susceptibility to movement with pressure surges, such as water hammer. Following Table lists applicable standards for Thermoset piping systems. b. Corrosion Resistance Like other plastic materials, Thermoset piping systems provide both internal and external corrosion resistance. For compatibility of Thermoset plastic material with various chemicals, see Appendix B. Due to the different formulations of the resin groups, manufacturers are contacted to confirm material compatibility. For applications that have limited data relating liquid services and resins, ASTM C 581 provides a procedure to evaluate the chemical resistance of thermosetting resins. c. Materials of Construction Fibreglass is the most common reinforcing material used in Thermoset piping systems because of its low cost, high tensile strength, lightweight, and good corrosion resistance. Other types of commercially available reinforcement include graphite fibres for use with fluorinated chemicals such as hydrofluoric acid; aramid; polyester; and polyethylene. The types of fibreglass used are E-glass; Sglass for higher temperature and tensile strength requirements; and C-glass for extremely corrosive applications. Most Thermo Set piping systems is manufactured using a filament winding process for adding reinforcement. This process accurately orients and uniformly places tension on the reinforcing fibres for use in pressure applications. It also provides the best strength-to-weight ratio as compared to other production methods. The other main method of manufacturing is centrifugal casting, particularly using the more reactive resins. Thermo Set piping can be provided with a resin-rich layer (liner) to protect the reinforcing fibres. The use of liners is recommended for chemical and corrosive applications. Liners for filament wound pipe generally range in thickness from 0.25 to 1.25 mm (0.01 to 0.05 in), but can be custom fabricated as thick as 2.8 mm (0.110 in) and are often reinforced. Liner thickness for centrifugally cast Thermoset piping generally ranges from 1.25 to 2.0 mm (0.05 to 0.08 in); these liners are not reinforced. If not reinforced, liners may become brittle when exposed to low temperatures. Impacts or harsh abrasion may cause failure under these conditions. Fittings are manufactured using compression moulding, filament winding and spray-up, contact moulding, and metered processes. Compression moulding is typically used for smaller diameter fittings, and filament winding is used for larger, 200 to 400 mm (8 to 16 in), fittings. The spray-up, contact moulding and mitered processes are used for complex or custom fittings. The mitered process is typically used for on-site modifications.
d. Operating Pressures and Temperatures Loads; service conditions; materials; design codes and standards; and system operational pressures and temperatures are established as described in Chapters 2 and 3 for plastic piping systems. Table 7-2 lists recommended temperature limits for reinforced thermosetting resin pipe. Table: Thermo Set Piping Systems Standards Standard ASTM D 2310 ASTM D 2996 ASTM D 2997 ASTM D 3517 ASTM D 3754 ASTM D 4024 ASTM D 4161 ASTM F 1173 AWWA C950 API 15LR
Application Machine-made reinforced thermosetting pipe. Filament wound fibreglass reinforced Thermoset pipe. Centrifugally cast reinforced Thermoset pipe. Fibreglass reinforced Thermoset pipe conveying water. Fibreglass reinforced Thermoset pipe conveying industrial process liquids and wastes. Reinforced Thermoset flanges.
Fibreglass reinforced Thermoset pipe joints using elastomeric seals. Epoxy Thermoset pipe conveying seawater and chemicals in a marine environment. Fibreglass reinforced Thermoset pipe conveying water. Low-pressure fibreglass reinforced Thermoset pipe. Source: Compiled by SAIC, Table: Recommended Temperature Limits for Reinforced Thermosetting Resin Pipe Materials Recommended Temperature Limits Resin Reinforcing Minimum Maximum 0 0 0 0 F C F C Epoxy Glass -20 -29 300 149 Fibber Furan Carbon -20 -29 200 93 Furan Glass -20 -29 200 93 Fibber Phenolic Glass -20 -29 300 149 Fibber Polyester Glass -20 -29 200 93
Fibber Vinyl Ester
Vinyl -20 -29 200 93 Ester Source: ASME B31.3, p. 96, Reprinted by permission of ASME. e. Thermoset Piping Support Support for Thermoset piping systems follow similar principles as thermoplastic piping systems. Physical properties of the materials are similar enough that the same general recommendations apply. Spacing of supports is crucial to the structural integrity of the piping system. Valves, meters, and other miscellaneous fittings are supported independently of pipe sections. Separate supports are provided on either side of flanged connections. Additionally, anchor points, such as where the pipeline changes direction, are built-up with a rubber sleeve at least the thickness of the pipe wall. This provides protection for the pipe material on either side of the anchor. Reinforced polyester pipe requires a wide support surface on the hanger. It also calls for a rubber or elastomeric cushion between the hanger and the pipe to isolate the pipe from point loads. This cushion is approximately 3 mm (1/8 in) thick. Following Table summarizes the maximum support spacing at various system pressures for reinforced epoxy pipe.120 0 Table: Support spacing for Reinforced Epoxy Pipe Nominal Pipe Size, mm (in) 25 (1)
MAXI MUM S UPPORT S PACI NG, TEMPERATURES 240C 660C 790C (750F) (1500F) (1750F) 3.20 2.99 2.96 (9.9) (9.8) (9.7) 40 (1.5) 3.54 3.47 3.44 (11.6) (11.4) (11.3) 50 (2) 3.99 3.93 3.90 (13.1) (12.9) (12.8) 80 (3) 4.57 4.51 4.45 (15.0) (14.8) (14.6) 100 (4) 5.09 5.03 4.97 (16.7) (16.5) (16.3) 150 (6) 5.76 5.67 5.61 (18.9) (18.6) (18.4) 200 (8) 6.10 6.10 6.04 (20.0) (20.0) (19.8) 250 (10) 6.10 6.10 6.10 (20.0) (20.0) (20.0) 300 (12) 6.10 6.10 6.10 (20.0) (20.0) (20.0) 350 (14) 6.10 6.10 6.10
M ( FT) AT
VARI OUS
930C (2000F) 2.87 (9.4) 3.35 (11.0) 3.78 (12.4) 4.33 (14.2) 4.82 (15.8) 5.46 (17.9) 5.88 (19.3) 6.10 (20.0) 6.10 (20.0) 6.10
1070C (2250F) 2.83 (9.3) 3.29 (10.8) 3.72 (12.2) 4.27 (14.0) 4.75 (15.6) 5.36 (17.6) 5.79 (19.0) 6.10 (20.0) 6.10 (20.0) 6.10
1210C (2500F) 2.65 (8.7) 3.08 (10.1) 3.47 (11.4) 3.96 (13.0) 4.42 (14.5) 5.00 (16.4) 5.39 (17.7) 5.73 (18.8) 6.00 (19.7) 6.10
(20.0) (20.0) (20.0) (20.0) (20.0) (20.0) Note: Te manufacturer for the specific product developed spacing values on long-term elevated temperature test data basis. The above spacing is based on a 3-span continuous beam with maximum rated pressure and 12.7 mm (0.5 in) deflection. The piping is assumed to be centrifugally cast and is full of liquid that has a specific gravity of 1.00. Source: Fibber cast, Plus RB-2530, The same principles for pipe support for reinforced polyester apply to reinforce vinyl ester and reinforced epoxy Thermoset pipe. Span distances for supports vary from manufacturer to manufacturer. The design of piping systems utilizing reinforced vinyl ester or reinforced epoxy pipe reference the manufacturer’s recommendations for support spacing. Each section of Thermoset piping has at least one support. Additionally, valves, meters, flanges, expansion joints, and other miscellaneous fittings are supported independently. Supports are not attached to flanges or expansion joints. Supports allow axial movement of the pipe. f. Thermoset Piping Burial Reinforced polyester, vinyl ester, and epoxy pipe may be buried. The same basic principles, which apply to burying plastic pipe, also apply for Thermoset pipe regarding frost line, trench excavation, pipe installation, and backfill. For operating pressures greater than 689 kPa (100 psi), the internal pressure determines the required wall thickness. For operating pressures less than 689 kPa (100 psi), the vertical pressure on the pipe from ground cover and wheel load dictates the required wall thickness of the pipe. g. Joining Common methods for the joining of Thermoset pipe for liquid process waste treatment and storage systems include the use of adhesive bonded joints, over wrapped joints, and mechanical joining systems. The application requirements and material specification for these fittings are found in various codes, standards, and manufacturer procedures and specifications, including: - ASME B31.3 Chapter VII; - ASME B31.1 Power Piping Code; - The Piping Handbook, - Fibber cast Company Piping Design Manual. h. Thermal Expansion When designing a piping system in which thermal expansion of the piping is restrained at supports, anchors, equipment nozzles, and penetrations, thermal stresses and loads must be analyzed and accounted for within the design. The system PFDs and P&IDs are analyzed to determine the thermal conditions or modes to which the piping system will be subjected during operation. Based on this analysis, the design and material specification requirements are determined from an applicable standard or design reference. The primary objective of the analysis is to identify operating conditions that will expose the piping to the most severe thermal loading conditions. Once these conditions have been established, a free or unrestrained thermal analysis of the piping can be performed to establish location, sizing, and arrangement of expansion joints or loops. Due to the cost of Thermoset piping, the use of loops is not normally cost-effective. The following procedure can be used to design expansion joints in fibreglass piping systems. The expansion joint must be selected and installed to accommodate the maximum axial motion in both
expansion and contraction. This typically requires that some amount of preset compression be provided in the expansion joint to accommodate for all operating conditions. In addition, suitable anchors must be provided to restrain the expansion joint; guides must be installed to assure that the pipe will move directly into the expansion joint in accordance with manufacturer requirements; and pipe supports, which allow axial movement, prevent lateral movement, and provide sufficient support to prevent buckling, must be included in the design. Table: Loop Leg Sizing Chart for Fibber cast RB-2530 Pipe Do mm (in)
Thermal Expansion, mm (in), versus Minimum Leg Length, m (ft) 25.4 mm 50.8 mm 76.2 mm 127 mm 178 mm 229 mm (1 in) (2 in) (3 in) (5 in) (7 in) (9 in) 33.40 1.22 m 1.52 m 1.83 m 2.44 m 2.74 m 3.05 m (1.315) (4 ft) (5 ft) (6 ft) (8 ft) (9 ft) (10 ft) 48.26 1.83 m 2.44 m 2.74 m 3.66 m 4.27 m 4.88 m (1.900) (6 ft) (8 ft) (9 ft) (12 ft) (14 ft) (16 ft) 60.33 2.13 m 3.05 m 3.66 m 4.88 m 5.79 m 6.40 m (2.375) (7 ft) (10 ft) (12 ft) (16 ft) (19 ft) (21 ft) 88.90 2.74 m 3.96 m 4.88 m 6.10 m 7.32 m 8.23 m (3.500) (9 ft) (13 ft) (16 ft) (20 ft) (24 ft) (27 ft) 114.3 3.66 m 4.88 m 6.10 m 7.62 m 9.14 m 10.4 m (4.500) (12 ft) (16 ft) (20 ft) (25 ft) (30 ft) (34 ft) 168.3 4.57 m 6.40 m 7.62 m 9.75 m 11.6 m 13.1 m (6.625) (15 ft) (21 ft) (25 ft) (32 ft) (38 ft) (43 ft) 219.1 5.18 m 7.01 m 8.84 m 11.3 m 13.1 m 14.9 m (8.625) (17 ft) (23 ft) (29 ft) (37 ft) (43 ft) (49 ft) 273.1 5.79 m 7.92 m 9.75 m 12.5 m 14.6 m 16.8 m (10.75) (19 ft) (26 ft) (32 ft) (41 ft) (48 ft) (55 ft) 323.9 6.10 m 8.53 m 10.4 m 13.4 m 15.8 m 18.0 m (12.75) (20 ft) (28 ft) (34 ft) (44 ft) (52 ft) (59 ft) 355.6 5.79 m 7.92 m 9.75 m 12.5 m 14.9 m 16.8 m (14.00) (19 ft) (26 ft) (32 ft) (41 ft) (49 ft) (55 ft) Notes: Do = outside diameter of standard Fibber cast pipe. Do may be different for other manufacturers. Thermal expansion characteristics and required loop lengths will vary between manufacturers. Source: Fibber cast, Piping Design Manual, FC-680, Reinforced Epoxies Although epoxies cure without the need for additional heat, almost all pipes are manufactured with heat-cure. Reinforced epoxy piping systems are not manufactured to dimensional or pressure standards. Therefore, considerable variation between manufacturers exists in regard to available size,
maximum pressure rating and maximum temperature rating. Performance requirements, including manufacturing, conform to ASTM standards in order to not sole-source the piping system. Reinforced Polyesters Reinforced polyester Thermoset piping systems are the most widely used due to affordability and versatility. The maximum continuous operating temperature for optimum chemical resistance is 710 C (1600 F). Like the epoxies, reinforced polyester piping systems are not manufactured to dimensional or pressure standards. Variation of available piping sizes, maximum pressure rating, and maximum temperature ratings exist between manufacturers. Performance requirements, including manufacturing, conform to ASTM standards in order to not sole-source the piping system. Reinforced Vinyl Esters The vinyl ester generally used for chemical process piping systems is biphenyl-A fumarate due to good corrosion resistance. Reinforced vinyl ester piping systems vary by manufacturer for allowable pressures and temperatures. Performance requirements, including manufacturing, conform to ASTM standards in order to not sole-source the piping system. Reinforced Furans The advantage of furan resins is their resistance to solvents in combination with acids or bases. Furans are difficult to work with and should not be used for oxidizing applications. Maximum operating temperatures for furan resins can be 189C (300F). Furan resin piping is commercially available in sizes ranging from 15 to 300 mm (½ to 12 in) standard. Testing of Non-Metallic Piping Systems Testing requirements, methods, and recommendations for plastic, rubber and elastomeric, and Thermoset piping systems are the same as those for metallic piping systems, with the following exceptions. The hydrostatic leak test method is recommended. The test pressure shall not be less than 1.5 times the system design pressure. However, the test pressure is less than the lowest rated pressure of any component in the system. PT = 1.5 P; and, PT < Pmin Where: PT = test pressure, MPa (psi); P = system design pressure, MPa (psi); Pmin = lowest component rating, MPa (psi). The documents should be prepared in the same way as in case on the metallic piping system testing.
