UNIVERSITY OF PETROLEUM & ENERGY STUDIES
HINDUSTAN PETROLEUM CORPORATION LIMITED
MANGALUR–HASSANBANGALORE/MYSORE LPG PIPELINE Summer Internship Report
Mahesh .V SAP ID 500026333 ROLL NO : 18 MTECH Pipe Line UPES Dehradun
Contents 1.0 Introduction: ........................................................................................................................................... 3 2.0 PIPELINE DESIGNING ............................................................................................................................... 4 2.1 Key parameters ....................................................................................................................................... 4 2.1.1 Main pipeline ....................................................................................................................................... 4 2.1.2 Spur Pipe Line.................................................................................................................................. 5 2.2 CODES AND STANDERDS ......................................................................................................................... 5 2.2.1ASME Standards .................................................................................................................................... 5 2.2.2ASTM Standards .................................................................................................................................... 6 2.2.3API Standards ........................................................................................................................................ 6 2.2.4 MSS Standards ..................................................................................................................................... 7 2.2.5 DIN/EN Standards ................................................................................................................................ 7 2.2.6 ISO Standards ....................................................................................................................................... 7 2.2.7 NACE Standards ................................................................................................................................... 8 2.2.8 Oil Industry Safety Directorate (OISD Standards) ................................................................................ 8 2.3 Pipeline and Associated Facilities Design................................................................................................ 9 2.3.1 Pipeline................................................................................................................................................. 9 2.3.2 Materials .............................................................................................................................................. 9 2.3.3 External Corrosion Coating .................................................................................................................. 9 2.3.4 Internal Corrosion Monitoring ........................................................................................................... 10 2.3.5 Insulating Joints ................................................................................................................................. 10 2.3.6 Pipe Wall Thickness ............................................................................................................................ 10 2.3.7 Sizing of Pipeline ................................................................................................................................ 11 2.3.8 Welding .............................................................................................................................................. 11 2.4 Basic Design Formulas........................................................................................................................... 12 2.4.1General Flow Equation........................................................................................................................ 12 2.4.1.1Effect of pipe elevation: ................................................................................................................... 12 2.4.2 Velocity of Gas in a Pipeline ............................................................................................................... 13 2.4.3 Reynolds No. ...................................................................................................................................... 14 2.4.4 Friction Factor .................................................................................................................................... 14 1
2.4.5 Compressibility Factor ....................................................................................................................... 15 2.4.6 Design Pressure.................................................................................................................................. 15 2.4.7 Pipe Weight ........................................................................................................................................ 16 2.4.8 Line Pipe Thickness ............................................................................................................................ 17 3.0 PIPELINE CONSTRUCTION PROCEDURE ................................................................................................ 19 3.1 Statuary Permission .............................................................................................................................. 19 3.2 Pipe Laying Activities:............................................................................................................................ 20 3.2.1 Movement and Staging of Pipeline Components and Construction Equipment: .............................. 20 3.2.2 Clearing and Grading.......................................................................................................................... 20 3.2.3Stringing .............................................................................................................................................. 21 3.2.4 Trench Excavation .............................................................................................................................. 21 3.2.5Cold Field Bending .............................................................................................................................. 22 3.2.6 Welding procedure ............................................................................................................................ 22 3.2.7 Weld Joint Numbering ....................................................................................................................... 23 3.2.8 Cleaning of Edges and Bevel Inspection ............................................................................................ 24 3.2.9 Lowering and Backfilling of Pipe Section ........................................................................................... 24 3.2.10 Hydro Testing ................................................................................................................................... 25 3.2.11 Final Grading and Reclamation ........................................................................................................ 26 4.0 PRECOMMISSIONING ............................................................................................................................ 27 4.1Precommissioning activities................................................................................................................... 27 4.1.1 System Check ..................................................................................................................................... 27 4.1.2 Checking of Field Instruments ........................................................................................................... 27 4.1.3 Survey of the Pipeline ........................................................................................................................ 28 4.1.4 Checking of Communication System ................................................................................................. 28 4.1.5 Checking of Electrical Distribution System ........................................................................................ 28 4.1.6 Checking of Instruments, Control & Interlock ................................................................................... 28 4.1.7 Checking of Utilities ........................................................................................................................... 28 4.2 Dewatering ............................................................................................................................................ 29 4.3 Swabbing ............................................................................................................................................... 29
2
1.0 Introduction: HPCL intend to build a LPG Pipeline from its LPG import facilities at Mangalore to receipt at Bangalore via Hassan and subsequently provided a spur to mysore via Kalibadi. The pipeline is proposed through the existing Mangalore-Bangalore pipeline corridor
The proposed HPCL LPG pipeline will starts from HPCL Mangalore LPG import facilities (MLIF) to receipt terminal at Devangudi , Bangalore via Hassan. The proposed LPG pipeline has a mainline length of 362km from Mangalore to Bangalore .The pipeline has tap-off for Hassan at chainage 164 km and is further extended to Mysore Terminal (106 km via Hassan).The proposed pipeline has 8.4 km length spurline to Yediyuru at chainage 294.45 km on mainline and 3.2 km length spurline to Solur at chainage 287.79 km on mainline .The pipeline has a further tap-off provision at Handanhalli village for extending the pipeline to Coimbatore.
The estimated Flow Rate of the proposed pipeline is 1.12MMTA (330.66 cum/h) & The operation hours of 16 hr. per day to be considered
3
2.0 PIPELINE DESIGNING 2.1 Key parameters
Pipeline Operating Life
: 35 years
Operating hours
: 16 hours per day (365 days/year)
Pigging
:
Facilities
.
Permanent pigging facilities suitable for Intelligent pigging” to all mainline and spur line
Subsoil Temperature
: 200C through the entire length of the pipeline (1.2 m below ground)
Pipeline Laying
Sectionalizing Valve
Pressure Control Valves Remote Operated Valves Pipeline Corrosion Protection
: Buried Station Premises SV: Under Ground Dispatch/Receiving Station/IP/Pump station Above ground : Sectionalizing valves have been proposed at maximum distance of 12km as per ASME B31.4 &OISD-24 and as per evaluation profile requirement : 1 PCV at each pump and receiving station : 1 ROV at each receiving station : External coating and impressed current Cathodic protection
2.1.1 Main pipeline
Main Pipeline Diameter Main Pipeline Length Material of construction Material Grade of Line pipe Pipeline Corrosion Allowance Design Pressure Design Temperature Thickness Pipeline Roughness
: 16”, 14”,10” &8” for Mangalore to Bangalore : 362.3kms : Carbon Steel : API5L Gr.X60 PSL 2 : 0.5 mm per cl.402.4 of ASME B 31.4 : 99.9 kg/cm2 : -20 to 650C : 7.9mm, 6.4mm (variance with dia.) : 45 microns
4
2.1.2 Spur Pipe Line
Spur Line Length
: 1) Hassan to Mysore (106km) 2) Intermediate dispatch station for Banglore to receiving Station Yadiyuru (8.40kms) 3) Tap-off Solour to receiving station solor(3.20) Spur pipeline Diameter : 10” (106kms) ,8”(8.40kms), 6”(3.20kms) Material of Construction : Carbon steel Material Grade of Line pipe : API 5L Gr.X60 PSL2 Pipeline Corrosion Allowance : 0.5 mm per cl,402.4 of ASME B 31.4 Design Pressure : 99.9kg/cm2 Design Temperature : -20 to 650 C Thickness : 6.4 mm of 10 inch ,8 inch & inch Pipeline Roughness : 45 microns
2.2 CODES AND STANDERDS The following codes and standards are used for the design of pipeline
2.2.1ASME Standards ASME B31.4
Pipeline transportation systems for liquid hydrocarbon & other fluids
ASME B16.47
Large diameter steel flanges (NPS 26 through NPS 60)
ASME B16.48
Steel line blanks
ASME B16.34
Valves- flanged, threaded and butt welding end
ASME B16.25
Butt welding ends
ASME B16.5
Pipe flanges and flanged fittings
5
ASME SEC VIII, DIV-1
Boiler and Pressure Vessel code
ASME SEC IX
Qualification slandered for welding and brazing
ASME B16.9
Factory-made wrought steel butt welding fittings
ASME B16.10
Face to face and end to end dimension of valves
ASME B16.20
Metallic Gaskets for pipe Flanges-Ring-Joint
ASME B31.3
Process Pipeline
ASME B36.10
Welded and seamless wrought steel pipe
2.2.2ASTM Standards ASTM A 53
Pipe, Steel, black and hot-dipped zinc coated welded and seamless
ASTM A 105/A 105 M
Carbon steel Forgings for pipe components
ASTM A 106
Seamless carbon steel pipe for high temperature service
ASTM A 320/A 194 M
Carbon and alloy steel nuts for bolts for high temperature service
ASTM A 320/A 320 M
Alloy steel bolting materials for low temperature service
ASTM A 330/A 333 M
Seamless and welded steel pipe for low temperature service
ASTM A 370
Mechanical testing of steel products
ASTM A 381
Metal-arc-welded steel pipe for use with high-pressure transmission System
ASTM E 112
Standard methods for determining the average grain size
2.2.3API Standards API 5L
Specification for line pipe
API 520
Sizing selection and installation of pressure relieving devices in refinery 6
API 540
Electrical installation of petroleum processing units
API 1104
Welding of pipeline and relative facilities
API 6D
Pipeline valves
API RP 1102
Steel pipeline crossing Railroad & highways
API 6 FA
Specification for fire test for valves
API 607
Fire test for soft-seated quarter turn valve
API 610
Centrifugal Pump for general refinery service
2.2.4 MSS Standards MSS SP 25
Standards marking system for valves, fittings, flanges and union
MMS SP 44
Steel pipeline flanges
MSS SP 75
Specification for high test wrought butt welding fittings
2.2.5 DIN/EN Standards EN 10204
Metallic products: types of inspection documents
EN 10045/1
Metallic products: Charpoy impact test-test methods(V &U notches)
DIN 30670
Polyethylene coatings for steel pipe and fittings
2.2.6 ISO Standards ISO 148
Determine the impact strength of steel and energy absorbed by charpy V-notch
ISO 15590- 1
Induction bends, fittings and flanges for pipeline transportation
7
ISO 9001
Quality Management Standards
2.2.7 NACE Standards MR0175
Sulphide Stress Cracking Resistant Metallic Material for Oilfield Equipment
2.2.8 Oil Industry Safety Directorate (OISD Standards) OSID –Stanadard-214
Cross country LPG pipeline
OSID–Standard-114
Hazardous chemical and their handling
OSID-Standard-113
Classification of areas for electrical installation
OSID-Standard-118
Layout for Oil and Gas Installation
OSID-Standard-119
Inspection of Pumps
OSID-Standard-141
Design and Construction requirement for Cross Country Hydrocarbon Pipelines
OSID-Standard-138
Inspection of Cross Country Pipeline Onshore
OSID-Standard-114
Liquid Petroleum Gas (LPG) installation
OSID-Standard-150
Design and safety requirement for LPG mounted Storage facility
OSID-Standard-163
Process Control Room Safety
8
2.3 Pipeline and Associated Facilities Design Pipeline and pipeline stations to be installed as a part of this project shall be designed and engineered in accordance with the standards/codes.
2.3.1 Pipeline Pipeline shall be designed in accordance with requirements of ASME B31.4 & OISD 214. The pipeline thickness shall be calculated using a design factor of 0.72. Higher wall thickness shall be used at river crossings, NH, SH, Railways, MDR & between NERIYA & SV06. For all other locations a design factor of 0.72 will be considered. At cased crossings higher wall thickness pipes may be used based on the requirements of concerned authorities. Pipeline shall withstand all installation, testing and operating conditions/loads. All necessary calculations should be carried out to verify structural integrity and stability of the pipeline for the combined effect of pressure, temperature, bending, soil/pipe interaction, external loads and other environmental parameters as applicable during all phases of work from installation to operation.
2.3.2 Materials Line pipe shall conform to latest edition of API 5L. Additional dimensional, NDT and other requirements over and above API 5L, shall be identified taking into account the construction, quality control and other aspects. Type of line pipe to be used shall be Seamless / LSAW / HSAW / ERW. Line pipe material grade shall be X65 for 406.4 mm (16”) OD & 355.6 mm (14”) OD and X52 for 273.05 mm (10”) OD & 219.85 mm (8”) OD pipelines.
2.3.3 External Corrosion Coating Pipeline to be installed below ground shall be protected against external corrosion by a combination of high integrity externally applied coatings and permanent impressed cathodic protection system. The selected corrosion protection coating will be suitable for the temperature range of + 70°C, In addition to the following properties: High integrity, Resistant to ageing and degradation , Resistant to attack by micro-organisms, Resistant to soil stresses , Ease of application, Resistant
9
to impact and mechanical damage during transportations. 3 Layer side extruded polyethylene coating will be provided on external surface of pipe confirming to DIN30670
2.3.4 Internal Corrosion Monitoring The corrosion monitoring system will be used to establish the internal corrosion profile of the pipeline using Electrical Resistance (ER) corrosion probes and Corrosion Coupons in conjunction with inspection technology. ER Probes and Coupons shall be located between the Barred Tee and the By-pass Valve. The ER probes and Coupons shall be retrievable type from the line under pressure. The ER Probe shall receive 4-20 mA signal proportional to corrosion rate from the transmitter through a two wire cable and provide digital display of corrosion rate through the same two wire cable. 4-20 mA signal shall also be available from the transmitter-corrosion meter for nterfacing with SCADA for online monitoring
2.3.5 Insulating Joints A monolithic insulating joint is needed for electrical isolation of over ground portion of the pipeline from buried portion. Insulating joints shall be monolithic type and shall allow smooth passage of pigs. The temperature and pressure range of insulating joint shall be in accordance with the indicated values on the relevant pipeline design condition and insulating joint data sheet. Wherever pressure / temperature transmitters are used on cathodically protected pipeline the same shall be electrically isolated by providing insulating fittings / flanges.
2.3.6 Pipe Wall Thickness Pipe wall thickness calculations shall be carried out in compliance with ASME B31.4 and OISD 214 and a corrosion allowance of 0.5 mm shall be added to the calculated thickness. Pipe thickness shall be checked and revised as required to minimize the no. of field hydro-testing sections, considering combined testing of pipes. In addition the selected thickness shall also be checked to ensure that the d/t ratio does not exceed 96, to avoid damage to pipe during handling and transportation. Additional requirement of higher wall thickness, if required, as per seismic analysis in the specific areas shall be provided
10
2.3.7 Sizing of Pipeline Description
Size (inch)
Length
Flow rate (MMTPA)
14
78.5
1.78
16
86.5
1.78
IP Hassan to Intermediate 10 Dispatch station for Bangalore Intermediate Despatch 8 station for Bangalore to Solur TOP Solur TOP to Devangudi 8 Bangalore
84.5
0.803
38.34
0.966
74.51
0.6179
Mainlines
Mangalore IP Station Neriya IP Station to IP Hassan
Spur lines
IP Hassan to Mysore
10
106.01
0.335
Solur TOP to Solur
6
3.20
0.282
IntermediateDispatch for Bangalore to Yediyuru
8
8.40
0.348
2.3.8 Welding Welding of pipeline section shall be carried out in accordance with API 1104 and OISD 214, specification for welding and welding charts. Butt welds shall be 100 % radio graphed for all pipelines. Welding and jointing qualifications shall be carried out in accordance with ASMEB31.4 and API 1104. In Plant Piping for tie-ins, hook-up of the pipeline launcher/receiver and other process facilities should be in accordance with P&ID’s. The electrode used in the welding is E7010 and E6010 having 3.2mm and 4mm respectively. The flux coated E6010 electrode is used for root pass and other is used for the further process. 80-110 A, 30-40 V direct current is used for this process.
11
2.4 Basic Design Formulas
2.4.1General Flow Equation
( )(
)
Q = gas flow rate measured at slandered condition ft3/day (SCFD) f = frictional factor ,dimensionless Pb = base pressure ,psia Tb = base tempaeture ,0R(460+F) P1 =upstream pressure , psia P2 = downstream pressure, psia G = gas gravity (air =1) Tf = average gas flowing tempreture , 0R (460+0F) L = pipe segment length, mi Z = gas compressibility factor at the flowing tempareture, dimensionless D = pipe inside diameter ,in
2.4.1.1Effect of pipe elevation: Case 1 (Single slope)
(
)(
)
12
Where:
(
)
s = elevation adjustment parameter, dimensionless H1 = upstream elevation ,ft H2 = downstream elevation , ft e = base of natural logarithms (e = 2.718…..)
Case 2: Multiple slopes
2.4.2 Velocity of Gas in a Pipeline
(
)(
)(
)
u1 = upstream gas velocity, ft/s Q = gas flow rate measured at slandered condition ft3/day (SCFD Pb = base pressure ,psia Tb = base temperature ,0R(460+F) Z = gas compressibility factor at the flowing temperature, dimensionless D = pipe inside diameter ,in
13
2.4.3 Reynolds No. ( )( )
Pb = base pressure, psia Tb = base temperature ,0R G = specific gravity of air (1.00) Q = gas flow rate, standard ft3/day D = pipe inside diameter , in µ = viscocity of gas , lb/ft-s
2.4.4 Friction Factor
i, Laminar Flow:
ii, Transition Flow:
√
(
√
)
Re > 4000
14
Where f = friction factor, dimensionless D = pipe inside diameter ,in e = absolute pipe roughness, in Re = Reynolds number of flow, dimensionless
2.4.5 Compressibility Factor
(
(
))
(
)
Pavg = Average pressure ,psig Tf Z
= Average temperature = compressibility factor
2.4.6 Design Pressure
15
Where: P = internal pipe design pressure D =pipe outside diameter, in t = pipe wall thickness, in S = specified minimum yield strength (SYMS) of pipe material E = seam joint factor,1.0 for seamless & submerged arc welded pipes F = design factor Usually 0.72 for cross country gas pipelines, but can be also low as 0.4 depending on class location and type of construction T = temperature deration factor=1.00 for temperature below 2500F
2.4.7 Pipe Weight
Where: w =pipe weight D = pipe outside diameter, in t = pipe wall thickness, in
t = (Pi D)/2s Pi : internal design pressure, psi(bar) D : outside diameter of the pipe in (mm) S
: minimum yield strength of pipe,psi (MPa)
16
2.4.8 Line Pipe Thickness The standard wall thickness is calculated in accordance with ASME B31.4,404.1.1;
tn = t+ A where tn : nominal wall thickness (mm) t : pressure design wall thickness as calculated in accordance with ASMEB 31.4 for internal pressure A : sum of allowance, in (mm)
t
Pi : internal design pressure, psi(bar) D : outside diameter of the pipe in (mm) S : minimum yield strength of pipe,psi (MPa) E : weld joint factor 0.72 : design factor of nominal wall thickness S = 0.72 * E* specified allowable stress value
For API 5L grade X60 pipe SMYS : 60,000 psi E
: 1.00
17
The calculated wall thickness ( tn) and slandered wall thickness (t selected) for the different Outer Diameter of pipes are as follows S.No.
OD(inches)
t(mm)
A(mm)
tm(mm)
t selected(mm)
1
18
7.52
0.5
8.02
8.7
2
16
6.68
0.5
7.9
7.9
3
14
5.84
0.5
6.34
6.4
4
12.75
5.53
0.5
5.83
6.4
5
10.75
4.49
0.5
4.99
6.4
6
8.625
3.60
0.5
4.10
6.4
7
6.625
2.77
0.5
3.27
6.4
18
3.0 PIPELINE CONSTRUCTION PROCEDURE 3.1 Statuary Permission
The Company shall obtain a general permission from the various authorities having jurisdiction over the area as necessary for construction of the pipeline. The responsibility of the Company ends with providing in principle approvals. Contractor shall obtain the necessary permits like work permit/ excavation permit/ trench opening permit etc. for all works from the authorities having jurisdiction before the actual execution of various phases of the works and all stipulations/ conditions/ recommendations of the said authorities shall be strictly complied with no extra cost to Company. Contractor shall also obtain all necessary permissions from the concerned authorities for installation of pipeline at railways, roads, water crossings and local authorities including places where blasting is required. Company may, however, assist Contractor in obtaining such permissions, wherever required, by issuing recommendation letters etc. In case of damage to other utilities/infrastructure, Contractor shall be responsible and the required compensation as per the directions of concerned authorities/ Company shall be paid by the Contractor. After completion of work, Contractor shall obtain a certificate from the concerned authorities that the job has been completed as per their requirement and the area/land has been restored to their satisfaction. Liasioning with the Mining authorities, if required, prior to laying of pipeline in the mining area to be undertaken by the Contractor and also the completion certification in respect to their satisfaction to be obtained. The conditions mentioned in the in principle approvals from statutory Authorities already obtained by the Company are enclosed with bid. All such requirements shall be shall be binding on the contractor.
19
3.2 Pipe Laying Activities: 3.2.1 Movement and Staging of Pipeline Components and Construction
Equipment: Pipe segments are normally delivered from their point of manufacture by rail to a rail offloading yard conveniently located to the construction ROW. From there, pipe segments are loaded onto flatbed trucks and taken to a material laydown yard that is temporarily maintained in an area close to the construction site. Numerous laydown yards may be constructed to support individual pipe construction spreads. A truck typically carries a maximum of 20 pipe segments at a time; however, this varies by pipeline diameter, wall thickness, weight, and pipe stacking method. Trucks will make round-trips all day between rail off-loading areas and material laydown areas until all of the materials assigned to the laydown areas have been delivered. The primary purpose is temporary storage of pipeline materials, laydown yards are also sometimes used for “double joining” two pipe segments before their delivery to the ROW. Laydown and staging areas could be in use from 3 to 12 weeks.
3.2.2 Clearing and Grading The survey crew will carefully survey and stake the construction ROW to ensure that only the preapproved construction workspace is cleared. The clearing and grading crew leads the construction spread. This crew is responsible for removing trees, boulders, and debris from the construction ROW and preparing a level working surface for the heavy construction equipment that follows. Depending on existing soil conditions, this may require bringing in additional materials such as stone and sand to create a temporary work road adjacent to the pipeline. The clearing and grading crew is also responsible for installation of silt fences along the edges of streams and wetlands as necessary to prevent erosion of disturbed soil. Trees inside the ROW are cut down, roots are excavated; and timber is stacked along the side of the ROW for later removal. In virtually all circumstances, topsoils and subsoils are separately stockpiled adjacent to the trench. The subsoil can be used to backfill the trench once appropriate bedding materials have been placed at the bottom of the trench and the pipe has been installed
20
3.2.3Stringing Pipes shall be unloaded from the trailers and lowered on to the ground by means of crane or other suitable equipment, using suitable lifting devices viz. lifting hooks and the bevel of pipe ends. Cranes shall be taken to avoid dragging and sliding. All stringing shall be carried out during daytime in light. An overlap of about 25mm shall be kept between adjacent pipes. No pipe shall be string before the trench is excavated to full depth and accepted by the client/MMPL to meet the requirement of the specification. Pipes of different wall thickness shall be strung separately. Pipe shall be strung with the use of two guide-ropes. Pipe shall be strung on sand bags in such a way so as to match the grade profile and trench profile. The sand bag shall be provided by the ACE.
3.2.4 Trench Excavation Pipeline trench shall be dug by any method that may be necessary or director on the cleared and graded right –of –way according to the routes as stated and approved by engineer in charge. In cumulative land and other areas specifically designed by the COMPANY, top 300mm of the arable soil on the pipeline trench top width shall be excavated and stored separately, to be replaced in original position after backfilling and compacting of the trench. The trench shall be made wide enough where slack loops are lowered into the trench so that no coating is rubbed or abraded at the sides. Normal cover and trench dimensions LOCATION a) Normal Terrain b) Industrial, Commercial and Residential area c) Rocky terrain d) Minor water crossing / canal / drain e) Drainage, ditches at roads/railway crossings f) Cased / Uncased road crossings g) Cased Railway Crossings h) Major River Crossings (Below scour level)
MINIMUM COVER (m) 1.2 1.5 1.5 1.5 1.5 1.5 1.7 2.5
i) Major River Crossings (Below scour level) Open Cut j) Marshy areas/areas prone to flooding
2.5 (Normal Soil) / 1.5 (Rocky) 1.5
21
3.2.5Cold Field Bending The machineries which are used in the bending process are Hydraulic Pipe Bending Machine with Lined Bending Die sets, Hydra Crane, Lifting/ Choker Belts, Holiday Testing Machine, D meter. The Pads, Dies and Rolls of the bending equipment shall have relatively soft surface to avoid damage to the pipe coating, wherever applicable, fully retaining bending shoe shall be used. The ends of the each bend length shall be not involved anyway in the bending. The length of the straight section shall permit easy joining .In no event shall the end of the bend be closer than 1.5m from the end of the pipe. For 10” OD Pipeline and smaller the radius of cold field shall not be less than 18D.Where D is the Outer Diameter of the Pipeline. Bending will be performed with machines that ensure continuous bending without wrinkles or undulation in the curved / pipe section. A bending mandrel is compulsory if D/t ≥50(outside diameter/ thickness) A bending mandrel must be used if, during bending, wrinkles or undulations occur or if the ovalisation tolerances cannot be respected. When the ambient temperature is less than 0 0C it is forbidden to bend P.E – coated pipes. The thickness of the pipe wall on the outside of the bend must remain within the tolerance limit given in the pipes
3.2.6 Welding procedure Welding procedure qualification can be carried out in accordance with the relevant requirement of API 1104 latest edition and Client’s specification .Welding shall be carried out by manual shielded Metal Arc Welding (SMAW).The proposed Welding Procedure Specification for the mainline welding is appended to this document for MMPL/HPCL review and approval, subsequent to approval of which the procedure Qualification Tests shall be carried out at site. The procedure qualification test shall be carried out by ACE under field conditions and shall be witnessed by MMPL/HPCL. Once welded specimens are visually cleared .It shall be subjected to Radiographic testing .Destructive testing shall be done as per API 1104 standard and MMPL Specification.
22
Shielded Metal Arc Welding (SMAW): The heat for this process is provided by an electric arc that melts a consumable electrode, with some of the metal being welded. When the weld metal cools, it hardens to form the weld. It having four process. a)Preheating b)Root pass c)Hot pass d) Filler 1 e)Filler 2 f) Tapping
A complete set of test results in the specified format shall be submitted to MMPL/HPCL for the approval immediately after format completing the procedure qualification tests. Standard tests as specified in the code shall be carried out in all class. In addition the change in filter metal from a different Supplier will require new qualification of applicable WPS. Visual inspection Company/ Consultant shall carry out inspection of all welds as per the latest edition of API 1104.All finished welds shall be visually inspected foe parallel alignment of the work, excessive reinforcement, concavity ,shrinkage ,cracks ,undercuts, dimensions, surface not exceed th limit specified in the applicable cod/standards Non Destructive Examination The girth weld of the coupons welded for Welding Procedure Qualification shall be subjected to 100% examination by X-ray Radiographic examination and manual Ultrasonic Testing. Welds shall meet the standards of acceptably as set forth in API 1104 latest edition as well as the requirement in MMPL specification. Destructive Testing Having passed the visual and the non-destructive testing, the test weld shall be subjected to mechanical test. Test shall be carried out at laboratory approved by HPCL/MMPL
3.2.7 Weld Joint Numbering Each of the welded joints in the pipeline shall be assigned with a unique joint number as described below:
Weld joint number shall be put on the adjacent factory coated portion of the pipe The weld joint numbering shall be done in the direction of flow
23
In each kilometer joint number shall starts from 0.1(example k00 MJ 01 to 82 or etc., K01 MJ 01 The joint numbering shall be as indicated below KXXX/ MYYY/W A ǀ B Where KXXX - Chainage in Kms MYYY - For main pipeline joint no. MYYYRW - Where cut outs are given, the first joint is defined by RW MYYYA - Additional joint shall be identified by suffix a, b, c, d
3.2.8 Cleaning of Edges and Bevel Inspection The edges to be welded shall be properly cleaned. In particular, ant oil, bitumen, grease and paint shall be removed by flame or solvent. Earth ,oxide, rust, sand and any other material, which could be determined to the weld, shall be removed by means of grinding and/ or a wire brush. This shall be effected inside and outside and for a minimum distance of 25mm from the edge of the weld bevel. The bevel shall be thoroughly inspected at the stage. Once pipe which have been cut back, a zone extending 25mm back from the new field bevel, shall be ultrasonically tested to the requirement of the line pipe specification to ensure freedom from laminations. The new bevel shall be subjected to 100% visual and 100 dye penetrant/MPI tests.
3.2.9 Lowering and Backfilling of Pipe Section Lowering Pipe in to Trench The pipeline section shall be lowered after inspection and wrapping of the welded pipeline section and clearance obtained for lowering from HPCL/MMPL. After satisfactory completion of the trench, bottom level shall be checked to get the required minimum cover. The pipe shall fit in the trench without being forced to remain in place until the backfilling operation is completed. Any extra excavation that may be required for this purpose shall be done. Before lowering in, a complete check by a calibrated full circle holiday detector for pipe coating (PE Coating) and for field joint coating shall be carried out using at 25 KV with a calibrated holiday detector. The examination shall the repaired as per the approved procedure and reholiday shall be done. In lowering the line vertical slack loops shall be placed at regular intervals. Slack loops shall move horizontally from side to side of the trench after lowering. Until
24
enough lowered line is securely anchored by back fill , slack loops shall be suspended above the trench on padded support of sufficient strength to prevent collapsing of the trench and in sufficient number as that the pressure at the points of support will not damage the coating and wrapping.
The bottom of the trench shall be pre-padded with a minimum of 0.15 M of loose earth/ sand in accordance with the specification given herein for rock trenching which might damage the protective coating and wrapping of pipe. Backfilling and Dressing the Trench Backfilling may in principle be started after the measurement like a) positioning of the pipe b) covering of the pipeline c) location of the welded joints, concrete slabs, ballast, connection of the telemetry cable, cable and connection boxes of the potential measuring points etc. d) Determination of the angles and the position of each change direction. These measurement s have been completed and the results communicated to the Owner and/or the Engineer.
Backfilling and bedding must be provided in a manner that will offer firm support for the pipeline and not damage either the pipe or the pipe coating by the type of backfill material used or subsequent surface activities. If the backfill material contains rocks or hard lumps that could damage the coating, care must be taken to protect the pipe and pipe coating from damage by such means as the use of mechanical shield material; backfilling procedures must not cause a distortion of the pipe cross section that would be detrimental to the operation of the piping and the passage of cleaning or internal inspection devices
3.2.10 Hydro Testing The section of the pipelines shall be tested as a single string. All welded joint shall be exposed and should be cleaned properly from rust and other foreign materials. The section of the pipeline section for the crossings shall be tested as a single string. The minimum hydrostatic test pressure shall be 1.4 times of the design pressure for gas pipeline. The combined equivalent stress in the pipeline due to bending and test pressure shall not exceed 90% of the SMYS of the pipe material. The test section shall be visually examined for leaks/ defects etc.
25
After the temperature has been stabilized, the pressure shall be maintained in the pipeline for at least 6 hours and recorded, “calibrated 6” dial pressure gauge one at pressure gauge one at pressurization point and at other highest point shall be installed during testing. Pressure gauge range should be 1.5 times of the test pressure. The accuracy of the pressure gauge to be used is ±0.1% of the full scale value. Before filling water in the pipe section all NDT, pipe log book part A except joint coating shall be completed. For testing of pipe section clean construction portable water shall be used. During filling of the water proper venting shall be done at the highest point to remove all the entrapped air.
Pipeline shall be gradually pressurized to the test pressure and intermediate checks shall be done for any possible leakage. During pressurization warning sign board shall be displayed as “ KEEP AWAY – SYSTEM UNDER PRESSURE”
3.2.11 Final Grading and Reclamation Once backfill has been placed and properly compacted, the original topsoil is returned to its original location and final grading and contouring are performed. Depending on the vegetation reclamation plan that has been approved, reclamation of the disturbed area above the pipeline can begin at this time. Also at this time, as all construction work is completed for each spread, construction equipment is removed and the construction ROW is reclaimed. However, depending on access constraints, the construction road may remain in place until adjacent spreads are completed, if it provides the only access to those spreads
26
4.0 PRECOMMISSIONING
Pre-commissioning checks shall be carried out for the pipeline system to ascertain that the pipeline system has been mechanically completed in all respect. These checks shall cover all the facilities of the main cross-country pipeline (starting from Mangalore Dispatch Station to Soluru Receipt Station and Spur Line from Hassan to Mysore as per the Scope of Work of individual Section Contractor)
4.1Precommissioning activities 4.1.1 System Check The entire facilities shall be checked against the latest P&ID’s, Engineering and Vendor drawings/ documents and other design specifications. Any shortcomings observed shall be listed down in the form of punch lists and these should be duly attended for liquidation and resolution. The Pipeline contractor should check the station systems from the angle of precommissioning and commissioning and spell out any additional requirement of vents/drains, temporary arrangement/modification etc. that may be required during the pre-commissioning and commissioning activities and arrange for the same in consultation with the Company representative.
4.1.2 Checking of Field Instruments All the field instruments/equipment like actuated valves, shutdown valves, transmitters ,solenoid valves, shut down switches, alarms etc. shall be checked physically and also for their intended application by simulating the actual conditions. It will also include checking of different meters, gauges, action of actuated valves, control valves, shutdown valves etc.
27
4.1.3 Survey of the Pipeline This shall be performed to confirm that proper fittings/supports, Cathodic protection system ,route markers, warning signs, fencing around SV stations, etc. have been installed along the pipeline.
4.1.4 Checking of Communication System This is to check that there is proper communication with adequate back-up power to ensure uninterrupted communication.
4.1.5 Checking of Electrical Distribution System This is to ensure safety and also to ensure an uninterrupted power supply during startup and normal pipeline operation.
4.1.6 Checking of Instruments, Control & Interlock This is to check that instrument controls and interlocks are functional as per the normal operating conditions.
4.1.7 Checking of Utilities This is to check that utilities like power, UPS system, CCTV/LPG/Diesel generator instrument air etc. are available prior to start-up.
28
4.2 Dewatering
Dewatering of a pipeline section shall be done subsequent to the hydro-test. During the dewatering operation, the major quantity of hydro-test water shall be removed from the main pipeline. It is the responsibility of the contractor to develop a suitable dewatering procedure and submit the same for Company's approval. The disposal of the water shall be performed such that no harm is done to the environment and the dewatering procedure should indicate this safe disposal methodology
4.3 Swabbing The swabbing operation shall consist of running several suitable foam pig trains using air as propellant through the pipeline. During swabbing operation, the residual free water content in the pipeline shall be reduced to an acceptable lower value
29
