Piping Design Tank Farm

Tank Farm

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Doc. No : DG-PP-72002

Rev. 00

CONTENTS Page No.

1.0

Purpose

3

2.0

Scope

3

3.0

Reference Code / Standard

3

4.0

Terms and Definitions

3

5.0

Abbreviations

4

6.0

General requirements

4

7.0

Test / Inspection

14

8.0

Documentation

14

9.0

Annexure

15

Date: 31-12-2007

File Name: DG-PP-72002-00 Copyright BecRel-All rights reserved

BecRel Engineering Private Limited

Tank Farm

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1.0

Rev. 00

Purpose To provide general guidelines and requirement for development of Tank farm layout and its associated facilities.

2.0

Scope This work instruction describes the procedure and methods to be used for the preparation of Tank Farm layout and processing of the statutory drawings for the approval of the chief controller of explosives in India.

3.0

Reference Code / Standard CCOE Regulations TAC Rules OISD –118 / 116 OSHA SMPV Rules (unfired ) The Petroleum Act API 12F

4.0

Terms and Definitions Flame arrester: In the event of lighting or another source of vapor ignition a flame arrester in the vent line o a storage tank prevents flames from flashing to the vapor inside the tank. Floating roof tank: A floating-roof lank is designed to conserve vapor loss and minimize fire hazard. Foam: This is a solution with a density lower than that of oil and water It is used to form a blanket over dangerous vapors and thereby reduce the risk of explosion. Heaters: These are heat exchangers used inside large storage tanks. They heat viscous materials using steam, hot water, or gases at high pressure. Sphere: This spherical vessel is used to store liquids and gases at high pressure. Date: 31-12-2007



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Intermediate holding tank: This tank is used for temporarily storing a liquid until it reaches a specified state, at which time it is pumped downstream in a process. Sediment: This sludge accumulates in tank and piping. It consists of dirt, wax, and mill scale and must he disposed of periodically. Sleeper: sleepers are steel or concrete supports , located at grade for piping systems commonly found in off sites. Sump: This is the low point wit hin an area used to collect liquids for removal. Tank farm: A location with many storage tanks is often called a tank farm.

5.0

Abbreviations OISD CCOE TAC OSHA NFPA API

− − − − − −

Oil Industry Safety Directorate Chief Controller of Explosives, Nagpur Tariff Advisory Committee Occupational Safety and Health Act National Fire Protection Agency American Petroleum Institute

6.0

General requirements

6.1

Piping Arrangement For Storage Tanks Steel containers are used for storin g liquids in a process plant. Although many such vessels are found within the confines of a process unit, most vessels and tanks are located in area commonly referred to as off sites or tank farms. The two most important factors governing these layouts are safety and economics. Any comprehensive design must consider local codes and regulations, client specifications, topography, adjacent process units, and neighbouring commercial or residential property as well as maintenance, operation, and constructabilit y. This document discusses the most common types of storage vessels plot plan arrangements, safety considerations, spill containment, pumping and general piping layout

Date: 31-12-2007



Tank Farm

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6.2

Rev. 00

Codes And Regulations The plant layout designer should review codes and regulations of the National Fire Protection Association, the Occupational Safety and Health Act, and regulations of local jurisdictions, such as Oil Industry Safety Directorate, Chief Controller of Explosives etc. All NFPA codes are recommended as a basis for legal regulations. They are intended to reduce % potential hazards to public safety, but compliance does not eliminate-' such hazards as those that occur When .flammable and comb ustible liquids are stored in process facilities. Factory Act The main considerations in the layout of storage facilities that fall under Occupational Safety-and Health; Act (OSHA) regulations are personnel access ladders, and stairways and catwalks Local Codes and Regulations Any documents concerning local codes and regulations should be reviewed before any off site layout is begun

6.3

Types of Tanks Storage tank come in many shapes and sizes, according to the type of product to be stored, its potential for fire, and the amount to be held. This section discusses the most common types of vessels found in most process facilities. Cone —Roof Tank This low-pressure tank is used for countless products, including petroleum, chemicals, petrochemicals, food products and water Another low-pressure storage vessel is the fiatroof tank Floating —Roof Tank The roof of this tank rises and lowers with the stored contents, thereby reducing vapor loss Date: 31-12-2007



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and minimizing fire hazard It is commonly found in oil refineries. Low-Temperature Storage Tank This tank stores liquefied gases at there boiling point. Products found in such tanks include ammonia (-28° F), propane (-43 7° F). Horizontal Pressure Tank (Bullet) Bullet tanks are usually shop-fabricated vessels used to store products under high pressure The heads of these vessels are either elliptical or hemispherical the latter being used when higher pressures are required Sphere Pressure Vessel This sphere is used to store large quantities of liquids and gases under pressure Limited road access to a plant site may make it more advantageous to erect a sphere in the field to store products under pressure 6.4

Spill Containment Because of the real risk of failure of storage tanks and primary piping systems, means must be provided to contain the resulting spills Containment may be a second tank wall around the vessel holding the liquid or a continuous dyke designed to hold all of the liquid stored in the largest tank Dykes may be constructed of earth, steel, concrete or solid masonry They may be square, rectangular, circular or irregular in shapes confirming to the natural terrain around them. Dykes may hold one or many tanks. OISD-118 / Petroleum Act should be consulted for matters that concern the dyking of flammable and combustible liquids Another dyke design commonly found in restricted or tight areas is the concrete wall The location of storage tanks often must be within the battery limits of a process unit, and earthen dykes are not practical for this application Tanks are often located in sloped or hilly areas where square or rectangular dykes would be impractical The designer should consider using the natural terrain for a group of tanks In addition. roadways and pumping facilities must be located to suit the terrain

Date: 31-12-2007



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When the overall plot plan for a process facility is developed off site storage should be set at a lower eleva tion than the process unit whenever possible This approach provides an additional margin of safety in the event of a major rupture. Developing a layout for buried storage tanks in an existing chemical plant often poses special problems It may not be possible or practical to move existing underground obstructions in the area in which the tank must be located One solution to this problem is to bury the tank above grade in a concrete containment. Pumps, maintenance access, and all appurtenances must be installed in the roof of the tank. Spills that pose a high risk to adjacent facilities must be diverted to a remote holding area. One method would be to erect a concrete diversion canal. Drain valves that are located outside the dyked area usually would be closed but would be opened in the event of a critical spill Sump drain lines discharge into the concrete diversion canal and flow downward to a holding basin. Refer Annexure-8 for General arrangement fo r Catch pit, Annexure-18 for typical underground arrangement. 6.5

Dyke Access Consideration must be given to providing vehicular and personnel access into dyked areas Personnel access should be by stairways designed according to Factory Act standards A single stairway located at the pump area provides access to a catwalk located on top of the dyke. Two other sta irways provide service access to the dykes When initially trying to establish a tank farm 1ayout the designer should consult local codes and regulations Rules for spacing between tanks and all adjacent facilities usually can be found in the latest issue of the industrial risk Insurers “GE Insurance Solutions or in Oil Industry Safety Directorate Rules and Petroleum Act. OISD-118 / Petroleum act will indicate what the designer should consider when grouping several tanks within a single dyke or whether the tanks should be individually dyked because of large capacities There is no simple answer to this layout problem Each plant site is unique, with different products, tank capacities fire prevention requirements terrain and adjacent commercial or residential property. . After the dyking arrangement has been established, there are a few additional factors to plan for The grade sloping away from the tanks to a sump must be determined minor spills

Date: 31-12-2007



Tank Farm

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and rainwater may have to be pumped from the sump to a treating pond Dyke heights must also be established on the basis of inventories and available real estate 6.7

Sizing Tanks And Dykes Development of optimum sizes for tanks and dykes comes through trial and error. Considerations include the availability of real estate, the possible use of standard-sized tanks for smaller capacities, and the nature of potential foundation design problems caused by early tank-size selections. The designer should refer to API 12F for standardized shopfabricated tank sizes. Larger field-fabricated storage tanks must be sized to suit each sizes. Dykes containing multiple tanks are sized to hold the capacity of the largest tank for the dimensions of dykes containing more than one tank, it is necessary not only to subtract the volume of each tank from the dyke’s capacity but to subtract the volume of the soil in each berm (foundation).

6.8

Tank Details After primary liquid-transfer line connections have been located, roof access ladders (or stairways) and side shell and roof maintenance access connections should be located addresses these issues. Refer Annexure-7 for Nozzle Orientation Tank maintenance includes such activities as internal inspection, cleaning, and repairs roof supports, and level instruments, Setting entrances to stairway or ladder areas at grade is the most convenient choice for operations personnel. It should be noted that stairways are not recommended for tanks whose diameter is less than 4.5m & height less than 6m. For safety, handrails should be added also on the tank roof edge on both sides of the ladder or stairway. Level instruments with internal floats are usually located in this area, as are roof maintenance access openings, which are convenient for inspections, repairs, and cleaning of instruments. The standard, round opening is a minimum of 0.460m in diameter. The larger, oval-shaped, flat-bottom opening is more commonly used on. large tanks or those that use internal heaters The layout designer must keep the area immediately around access openings free of such obstructions as large pipe supports, piping, and light poles Valve access catwalks shall be provided It is of utmost Importance to give operations personnel adequate access to primary tank valves Consideration must be given to the

Date: 31-12-2007



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elevation of all valve hand wheels in relation to the catwalk Adding extension stems to smaller valves will facilitate opening or closing such valves Tank mixers: A tank mixer is another auxiliary piece of equipment found in tanks with highly viscous fluids Adequate area must be provided for removal of tank mixers Tank heater: The heaters co me in various sizes and shapes sufficient unobstructed space must be provided outside access openings to permit removal of heaters Interconnecting Walkways : For storage areas with many small or medium sized tanks, consideration should be given to designing interconnecting catwalks for operator convenience The limiting factor is catwalk length Travel distance to exists in high-hazard industrial occupancies shall not exceed 23m Additional length can be accommodated by adding ladders or stairways. Refer Annexure – 9. Tank Supports Three common tank support designs are Concrete ring wall, Compact soil, Concrete table The civil engineer is responsible for determining the most cost-effective design, on the basis of available data about soil conditions. Layout designers should understand the fundamental nature of each design to optimize piping, stairway and ladder locations without creating problems for cons truction or plant personnel. Refer Annexure – 11 for concrete ring wall. For a low-temperature tank foundation design concrete table design is used This particular design employs a concrete slab supported by columns, providing an air space under the slab This air space helps raise the temperature of the slab during a failure in the primary tank Pumps shall be located outside the dyke Tank outlet piping can either penetrate the dyke or pass over. The latter approach would usually be considered if the maximum dyke height were 1.8m and if the minimum liquid level in the tank would not cause damaging cavitation in the pump The designer must carefully examine each layout before employing this design The location of an elevated pipe rack or sleeper relative to the pumps should account for plant maintenance philosophy Sleepers permit unobstructed pump access when located between the pump and the dyke wall Pumps pipe racks support discharge piping

Date: 31-12-2007



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but limit access to pumps during maintenance. Prime consideration should be given to providing an ample maintenance area around and above pumps. Locating pumps inside a concrete dyked wall is common in many process plants. In this design the pump block set at the same elevation as the dyke. With this configuration, the pump would not be submersed during a spill inside the dyke This configuration enables a close-coupled piping arrangement Providing for differential settlement allows the discharge line to be run to the pipe rack over the dyke wall This approach should be approved by the client. Lines penetrating concrete dyke walls against leakage by using commonly available seals. The seal is used when an insulated line runs through a larger pipe sleeve that must be sealed on the inside of the dyke This design permits minor line movement A stress or support engineer should be consulted when the designer is planning its application. 6.9

Differential Settlement This concern must be addressed early in the layout of any process unit or tank farm The foundation of any process facility will eventually settle or sink to some extent depending on the weight it carries and the condition of the soil. To determine where pipes may be supported safely without imposing excessive stress on equipment nozzles, a civil engineer and soil exports must work together to determine how much the foundation is likely to settle. subtracting sleeper settlement from tank settlement yields the differential settlement between the two By figuring line size wall thickness, and allo wable stresses distance between tank and first line support can be established Differential settlement can also be caused by tilting of the tank by out-of-plane settlement or by dishing of the tank bottom (which is a result of greater settlement at the center of the tank than at the edge) The optimum piping arrangement in a tank farm, as elsewhere in a process facility, is the most direct route between two points allowing for normal line expansion and stresses Annexure-3.1 & 3.2 illustrates piping between tanks and pumps , or places where piping movement is restricted, must be established Tank nozzles are one such anchor point The second anchor point may be the pump nozzle if line growth is permitted through the dyke or it may be anywhere along the pip ing within the dyke or at the point dyke penetration To minimize the potential for tank spills, expansion joints should not be used. Annexure-3.1 & 3.2 shows how to accommodate line expansion between tank nozzles and

Date: 31-12-2007



Tank Farm

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a manifold header. Expansion loops may be added at the sleeper level, as shown In a cross section of piping, pumps, dykes, and a primary pipe way that is typical of what might be fo und with in a tank farm Because the primary pipe way is located to the left of the roadway, pump-discharge lines across the road must be routed to the headers in one of two ways by burying them under the road, making allowances for vehicular loads imposed on the pipe, or by placing them over the road on a pipe bridge Client preference should be considered in this design Adequate access to pumps on the side of the pipe way opposite the road must also be provided. Annexure-4 In a bullet-tank piping layout tanks are set at the lowest possible elevation to satisfy pump head requirements A catwalk is located across all tanks to provide sufficient access to operating valves and instruments Liquid outlet piping to the pumps should allow for differential settlement and line flexibility. A typical piping arrangement for a high-pressure sp here is shown in Annexure-5 & 6 Layout factors for spheres include Ÿ Ÿ Ÿ

Sphere elevation should be kept low but not less than 1.525 m above grade. Ideally, each sphere should have it own stairway Figure shows an acceptable arrangement of stairway Valves should be installed as close as possible to all nozzles

If an above-grade conventional layout is preferred for liquefied natural gas tanks. NPSH requirements usually necessitate locating the pumps in a pit when the tank is above grade. For underground tanks a submersible pump and its motor are Located within a containment vessel and supported on lugs An adequate clear area directly over the pumps must be maintained to allow pump removal for maintenance Motor-operated header valves are located at grade and made accessible by platforms. Individual suction and discharge valves are located near the nozzle connections in the pt Safety requires that a water-deluge firefighting system be included in this layout as well as a sump and sump pump to remove unwanted water When high-pressure bullet tanks are located close to a process unit, a protection berm (or explosion proof wall) is often used. Berm length is slightly longer than the width of the tank area, and the berm height is roughly equal to the height of the tanks. These berms offer some protection in the event of an explosion.

Date: 31-12-2007



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Although foam fire-fighting systems are often supplied by companies specializing in fire protection, a basic understanding of such system is beneficial to a layout specialist The piping usually has quick-connect coupling located outside the dyke The line is routed to the tank wall A foam maker- which essentially consists of a pressure gauge, an air strainer and a check valve- is located in the vertical riser The foam solution enters a foam chamber located at the edge of the tank roof and then discharges across the top of the liquid in the tank. In another way foam concentrate from a truck or tank is supplied to a foam maker located outside the dyke wall. The foam may be injected into the regular product transfer piping or routed directly to storage tank through a permanent line especially for that purpose. An alternative to mobile fire-fighting equipment permanent hydrants and monitors may be used for fighting fires in storage tank areas Local codes and regulations as well as the TAC rules must be consulted to establish the appropriate coverage of water for a given layout The fire water piping around this area must come from two supply sources should any part of the system fail. Refer Annexure – 17. In an effective overall layout of a process and off-site plot plan, the administration area is immediately inside the plant main entrance as are maintenance and fire- fighting equipment Process units and the utility plant are located in the central and side word section of the plot. Truck and allowances for future-expansion are made. Storage tanks are located in the other side sections of the plot. Truck and rail loading and unloading areas are located together with storage tanks in co rners of the plot. A flare stack, a cooling tower, and treating ponds are in the far most corner. 6.10

Guidelines For Preparation Of Drawings For ‘CCOE’ Approval Common Guidelines Following are the requirements, which should be followed in layouts falling under CCOE’s purview. Suitable notes should be added on the ‘CCOE’ drawings to take care of these requirements. Layouts should meet the requirements of applicable statutory / OISD and TAC rules, they should be incorporated to reduce insurance premium on the tank farms. This should be done in consultation with the client.

Date: 31-12-2007



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Layouts must be submitted to and approved by CCOE before starting construction work. All the equipment shall be supported on concrete columns. Steel supports, if provided, shall have concrete encasing. Encasing to extend upto the joint of support and the equipment. Tanker loading & unloading area shall have concrete paving. However, concrete paving may not be required if this area is located on proper road. Finished floor inside tankfarm shall be RCC paved / unpaved / compacted earth. Type of floor to be finalized in consultation with the client. Design and construction of tanks and bullets shall be in accordance with relevant Indian / International Standards & Codes and shall also meet the requirements laid down by applicable stat utory regulations. All fittings such as pressure relief valves, level gauges, emergency shut-off valves on the tanks and bullets shall be in accordance with Indian / International Standards & Codes and shall also meet the requirements of applicable statutory regulation. All valves shall be cast & forged steel construction and tested as per relevant Standards & Codes. Cast iron valves are not acceptable. The design of electrical apparatus such as earthing, lighting, motors, switches etc. shall be in accordance with Indian Standard & Codes and shall also meet the requirements of applicable stat utory regulations. All electrical equipment shall be suitable for the hazardous area classification as shown in hazardous area classification drawing for the project. All electrical equipment shall be earthed with two separate earth conductors. An earth bus shall be provided near tanker loading / unloading area to enable earthing of the tanker with flexible earth connections. Fire fighting scheme proposed for this tankfarm shall be shown in the layout drawings. This shall consist of water hydrants and monitors as required by TAC regulations.

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Medium velocity spray systems 1 fixed foam systems shall be provided for the tankfarm as required by Insurance requirements and as agreed with the client. Any building / shed inside the fence shall be of fireproof construction. Minimum two gates shall be provided for the fenced area. The layouts shall be reviewed with respect to the attached check list Annexure-1 before they are issued for approval to CCOE. The equipment layouts shall be processed as per Annexure-12 Records Drawings & documents for CCOE approva l shall be treated as Quality document. Drawings / documents with check prints shall be maintained.

7.0

Test / Inspection Not Applicable

8.0

Documentation Not Applicable

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Annexure Annexure 1 Annexure 2 Annexure 3 Annexure 4 Annexure 5 Annexure 6 Annexure 7 Annexure 8

− − − − − − − −

Annexure 9 Annexure 10 Annexure 11

Check points for CCOE layout Flow Diagram for CCOE Drawing 3.1 & 3.2 – General Arrangement of Tanks Sectional Detail of Tank Layout General arrangement of Sphere Layout Sectional Detail of Sphere Layout Nozzle Orientation of Storage Tank Typical arrangement plan of channel interceptor in Tank bund & connection to Manhole − General arrangement of Platform’s − General arrangement of Tank - Section − Tank Foundation Drawing

Annexure 12 Annexure 13 Annexure 14 Annexure 15

− − − −

Layout Drawing for CCOE Approval Typical Pump Piping Typical Manifold Piping Level Transmitter

Annexure 16 Annexure 17 Annexure 18

− − −

Culvert Drawings U21 Drawing for Fire Protection System Typical Underground arrangement for Tank Farm

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Annexure -1 Check points for CCOE Layouts 1. Drawings are prepared as per applicable statutory rules. (Petroleum rules, SMPV rules O.I.S .D. rules) (O.I.S .D. rules only f specifically required by the Client). 2. All dyke walls are minimum I m height. 3. All ‘CCOE’ tanks Containing class A’ or/& class B’ fluids & having diameters larger than 4 mts. are located In such a way that the spray water requirement is minimized, particularly In cases where spray water requirements govern the pump capacities. 4. The requirement in clause 3 above is met even though foam protection is specified initially. 5. The spheres & bullets containing flammable liquids shall be located at 15 m clear distance from each other as far as possible to reduce aggregate spray water requirements. This is essential for large spheres & bullets, where the spray water requirements govern the pump capacities. 6. Volume of dyke is 110% of the largest tank as required by TAC. 7. Interceptor if required is shown in the drawings. Interceptor capacity / size are as per process data sheet. 8. Standard notes are attached to the drawing, with a project document number added on the drawing. 9. Reference drawings indicated on the drawing include the following: a) Plot, plan b) P & I Diagram c) Mechanical drawings for. equipment d) Hazardous area classification drawing (if made for the concerned project).

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Annexure -2 Flow Diagram For CCOE Drawing

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Annexure-3.1 General Arrangement Of Tanks

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Annexure-3.2 General Arrangement Of Tanks

General Tank Layout For Utility Services.

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Annexure -4 Sectional Detail Of Tank Layout

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Annexure -5 General Arrangement of Sphere Layout

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Annexure -6 Sectional Detail Of Sphere Layout

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Annexure -7 Nozzle Orientation For Storage Tank

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Annexure -8 Typical Arrangement Plan Of Channel Interceptor In Tank Bund And Connection To Manhole

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Annexure -9 General Arra ngement of Platforms

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Annexure-10 General Arrangement of Tank Section

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Annexure-11 Tank Foundation Drawing

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Annexure-12 Layout Drawing For CCOE Approval

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Annexure-13 Typical Pump Piping

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Annexure-14 Typical Manifold Piping

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Annexure-15 Level Transmitter

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Annexure-16 Culvert Drawing

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Annexure -17 U21 Drawing for Fire Protection System

Annexure -18 Typical Underground Arrangement

Piping Design Tank Farm

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