Tank Piping

CONTENTS Page 0.0 Cover Sheet 1 List of illustrations 2 1.0 General 3 - 4 2.0 Key Words 4

3.0 Bund Area to Contain Spillage 4 - 5

4.0 Tank Details 5

5.0 Pump Location in Tankfarm 5

6.0 Piping Arrangement 6 Applicable Revision: Prepared: Date: Checked: Date: Approved: Date: First Edition: R0 Prepared: AKB Date: Checked: TNG Date: Approved: RUD Date:

LIST OF ILLUSTRATIONS

SR.NO. DWG.NO.

DESCRIPTION

1 TFP1 TYPICAL TYPE OF DYKES 2 TFP2 DRAINAGE FROM DYKE

3 TFP3 TYPICAL HORIZONTAL PRESSURE TANK (BULLET) 4 TFP4 TYPICAL VERTICAL TANK DETAILS

5 TFP5 VALVE ACCESS CATWALKS 6 TFP6 TYPICAL TANK HEATERS

7 TFP7 TYPICAL FLOATING ROOF TANK ACCESS

8 TFP8 LOW TEMPERATURE TANK FOUNDATION WITH ELEVATED CONCRETE BASE

9 TFP9 COMPACTED FILL TANK PAD 10 TFP10 TYPICAL RING WALL FOUNDATION 11 TFP11 PUMPS INSIDE DYKED AREA 12 TFP12 PUMPS OUTSIDE DYKED AREA

13 TFP13 PUMPS INSIDE CONCRETE DYKED AREA 14 TFP14 DYKE-PENETRATION SEAL

15 TFP15 FLEXIBLE DYKE SEAL

16 TFP16 ALTERNATE PIPING LAYOUTS 17 TFP17 TANK PIPING LAYOUT

18 TFP18 CROSS SECTION OF PIPE WAY AND PUMPING 19 TFP19 BULLET-TANK PIPING LAYOUT

20 TFP20 LIQUEFIED NATURAL GAS TANK LAYOUT 21 TFP21 LIQUEFIED NATURAL GAS TANK LAYOUT

22 TFP22 TYPICAL FIRE WATER SYSTEM IN TANKAGE AREA 23 TFP23 PROTECTION BERM

1.0 GENERAL

1.1 The study of the tankfarm consisting of a group of tanks shall be carried out keeping the following basic points in consideration.

1.2 Grouping of tanks,

Specification of the content. Capacity of tanks

Nature of hazard - fire - _toxic - _explosive - _corrosive

- _{bulk handling loading} unloading Statutory distance

Requirement of Dykewall or curbing Dykewall height or curb height calculation Location of Pumps - inside dyke area

- _{outside dyke area} Approach to tank nozzles with valve Approach to tank roof

Drainage of dyke area - Sump and pump Road around tankfarm

Fire hydrant / monitor requirement

Underground system connected to specific system of treatment / disposal

1.3 Storage tanks located in a safe area and grouped according to the contents are called tankfarm. Normally, in chemical plants, the storage shall be either input raw material or output products or intermediate chemicals storage.

Storage tanks may contain acids, alkalis, oil viz. petrol, diesel, naptha, fuel oil or benzene etc. Oil, acid, alkali are usually stored in vertical storage tanks designed as per API 650.

1.4 Tanks should be grouped or segregated according to the contents. Tanks containing hydrocarbons should be separated according to the flash point, CCE classification for space planning, dykewall and its height requirement.

Layout of the storage facility shall be based on the following considerations and systematic approach.

- _{Statutory Regulations viz. CCE} - _{TAC/NFPA recommendations}

- _{Safety requirements as per OISD, OSHA, HAZOP study}

- _{Valve access platform / ladders at the piping outlet nozzles of tank.} - _{Access to top of tanks and interconnecting walkway}

- _{Piping on sleepers or piperack inside dyke area.} - _{Pumps location outside dyke area}

1.5 The practical objective to prepare a most economical plot plan and piping arrangement for a tankfarm should be to keep provisions of operational ease, maintenance facility, safety arrangements and overall aesthetics.

The tankfarm shall also have provisions for efficient drainage and disposal facility as required for various kinds of fluid storage.

The tankfarm should be secured against unauthorised entry by fencing, security gates depending on the tank storage capacity or the type of hazards posed by the nature of contents.

2.0 Key Words

Atmospheric tank - The tank that operates at pressure levels ranging from atmospheric pressure to 0.5 psig.

Bullet - This is a high pressure horizontal storage vessel shaped like a bullet (Refer Fig.TFP3) Cone-roof tank - This is a low-pressure vertical storage tank with a cone-shaped fixed roof.

Fixed roof tank - This is a low pressure vertical storage tank with a roof welded to the shell irrespective of roof design or method of support.

Floating roof tank - A floating roof tank design is adopted to conserve vapour loss and minimise fire hazard. (Refer Fig.TFP7)

Double-wall storage tank - A double wall storage tank has an inner wall to contain a liquid, an annulus space usually filled with insulation and outerwall for containment of spillage.

Horton sphere - It is a spherical vessel used for storage of high pressure liquid and gases.

Dyke - A dyke is a barrier designed to contain liquid in the tank in case of emergency within the area for safety reasons. (Refer Fig.TFP1)

Diversion dyke - This is a barrier designed to divert spillage from other storage tanks. It uses natural terrain to direct liquids to the sump area.

Flame arrester - In the event of lightning or another source of vapour ignition, a flame arrester in the vent line of a storage tank prevents flames from flashing to the vapour inside the tank.

Breather valve - This is provided as a measure to protect the tank against collapse due to sudden creation of vacuum inside the tank during suction by pumps.

Foot valve - This valve is provided at the bottom of a riser in a tank where a submersible pump can be installed. During regular operation, foot valve remains open.

Sleeper - Sleepers are steel or concrete supports usually located within 450mm of grade of piping systems commonly found in offsites.

Sump - This is the low point basin within an area used for collection of liquid waste for disposal. Foam - This is a solution with a density lower than that of oil and water. It is used to form a blanket over dangerous vapours and reduce the risk of explosion.

3.0 BUND AREA TO CONTAIN SPILLAGE

3.1 The risk of failure of storage tanks and the primary piping systems is reduced to certain extent, if the fluid is contained within the bund wall and is not allowed to spread throughout the area resulting in various hazards like fire, toxic spread, pollution problem etc.

3.2 The dyke may be constructed of earth, concrete, solid masonary or steel. It may be square, rectangular, circular or irregular in shape, conforming to the natural terrain around the tank.

3.3 The containment dyke for tankfarm under the purview of chief controller of explosives (CCE) shall be planned according to the CCE rules and regulations. CCE rules are applicable to the fluids of petroleum and petroleum products classified as class A, B or C according to its flash point characteristics.

The rules of CCE can be followed for other hazardous / inflammable products as good guidelines of safety, even though the product is not classified as petroleum product.

3.4 One common method of dyke construction is by earth upto a height of 1.8m and with width of dyke on top to be about 600mm. The slope on the surface of dyke is usually 1:1.5 consistent with the angle of repose of earth.

In congested area or where space is limited, usually concrete dyke is made with varying height for different containment capacity.

3.5 The free volume of the bund area is sized to contain the contents of one largest tank plus a margin of 10 percent.

3.6 All drains from the dyke area should be equipped with a valve outside the dyke regardless of whether the drainage goes to disposal pit or sewer system. This prevents liquid spillage from entering the sewer or released from the dyke area.

These valves should be kept closed and blanked off except when withdrawing water.

The contamination of spillage with the natural rain water or wash water needs this drainage to be treated before disposal. Depending on the contamination, the valve can be used for diverting either to storm water system or to the Effluent Treatment Plant.

3.7 Access to the dyke area is usually provided by making vehicular ramp at one end and a stepped entry at the other end (Refer Fig. TFP2)

4.0 TANK DETAILS

4.1 A typical illustration on the top of a vertical storage tank is given in Fig.TFP4

4.2 Valve access catwalk (Fig.TFP 5), Tank heater installation (Fig.TFP6), Floating Roof Tank access (Fig.TFP7) are illustrated as typical examples.

4.3 A low temperature tank foundation with elevated concrete base is illustrated in Fig.TFP8

4.4 A tank located on compacted granular fill is illustrated in Fig.TFP9 and a tank on the ring wall foundation is illustrated in Fig.TFP10.

5.0 PUMP LOCATION IN TANKFARM

5.1 To determiine the optimum location of pumps, the potential hazards and client preferrence shall be considered.

Fig.TFP11 and TFP13 illustrates the location of pump within the dyke area with the curb wall height of approx. 400-500mm.

This design protects the pump from minor spillage within the dyke and enable the discharge piping to exit the dyke over the wall and there is no need to have dyke penetration seals.

The piping outside the dyke may run on a piperack or sleepers. 5.2 The pumps located outside the dyke area are illustrated in Fig.TFP12.

Tank outlet piping can either penetrate the dyke or pass over the dyke in case the minimum liquid level in the tank do cause cavitation in the pump.

5.3 Adequate maintenance area around the pump shall be the prime consideration for planning the piping arrangement at suction as well as discharge.

6.0 PIPING ARRANGEMENT

6.1 The Optimum piping arrangement in a tankfarm is the most direct route between two points allowing for normal line expansion and stresses.

Fig.TFP16 illustrates between tanks and pumps.

Fig.TFP17 shows how to accommodate line expansion between tank nozzles and a manifold header. Expansion loops may be added at the sleeper level.

6.2 Fig.TFP18 illustrates a cross-section of piping, pumps, dykes and a primary pipeway in a typical tankfarm.

6.3 A bullet tank piping arrangement is shown in Fig.TFP19.

Tanks are installed at the lowest possible elevation to satisfy the pump head requirements.

A catwalk is usually located across all the tanks in a row to provide access to the operating valves and instruments.

Liquid outlet piping to the suction of Pump shall allow for differential settlement and the flexibility of the piping.

6.4 A typical layout of liquefied natural gas (LNG) tanks is shown in Fig.TFP20 and TFP21. The secondary containment is a steel lined concrete structure.

There is heavy cryogenic insulation between primary and secondary containers. Submersible pumps are located at the bottom of the pump shaft.

The roof is steel and domed.

The operation platform, piping and jib crane structure are supported on the concrete containment wall.

6.5 In addition to the provisions for mobile fire-fighting equipment, permanent hydrants, monitors are used for protection against fire in the tankfarm areas.

The codes, regulations viz.CCE, TAC, NFPA shall be consulted to finalise the safety requirement of the tankfarm.

Fig.TFP22 shows a typical arrangement of firewater hydrants and monitors in a tankfarm. The fire water piping around the tankfarm area shall be provided with supply from two different sources. This is normally done by installation of an firewater pump with diesel engine drive in addition to the electric motor driven pumps.

6.6 When high pressure bullet tanks are located close to the process unit, a protection berm (Refer Fig.TFP23) is normally used. The berm length shall be slightly longer than the width of the tank area and the berm height will be equal to the height of tanks. These berms are provisions for protection against explosion.

6.7 The sump and sump pump shall be provided for disposal of water accumulation due to rain or fire-fighting.

6.8 The foam piping shall be arranged with the quick-coupling to the line supply to the foam chamber at the edge of the roof of the tank. The coupling shall be located outside the dyke wall.

VARIES 2'/600 MIN. TOE OF DYKE W H 3'-6'/900-1800

ABOVE INTERIOR GRADE

EARTHEN DYKE W : H = 1 1/2 : 1

AS REQUIRED

CONCRETE DYKE

DOUBLE CONTAINMENT DYKING METHOD

CONCRETE CONTAINMENT EARTHEN CONTAINMENT

EARTHEN AND CONCRETE COMBINATION DYKE

25'/7.6

EARTHEN DYKE CONCRETE DYKE

DIVERSION CANAL TO REMOTE AREA SUMP (TYP) DIVERSION CANAL VALVES USUALLY CLOSED

CONCRETE DIVERSION CANAL

PUMP AREA C PLANT ROAD

VEHICULAR RAMP

STAIRWAY

VEHICULAR AND PERSONNEL ACCESS

DRAINAGE FROM DYKE

DWG. NO.: TFP2

TYPICAL HORIZONTAL PRESSURE TANK (BULLET)

SLOPE

PRIMARY TRANSFER PIPING C LEVEL GAUGE_L

C LADDER_L

TANK ROOF MAINTENANCE ACCESS

ALTERNATE ACCESS MAINTENANCE ACCESS FOR CLEAN-OUT DOOR

STAIRWAY ENTRANCE AT GRADE

PROVIDE HANDRAIL ON BOTH SIDE OF ROOF ACCESS AREA

TYPICAL VERTICAL TANK DETAILS

DWG. NO.: TFP4

ROOF ACCESS AREA

PLAN

TANK

ELEVATION

VALVE

EXTENSION STEM

VALVE ACCESS CATWALKS

CATWALK

FINNED TUBES STEAM IN CONDENSATE OUT OUT CONDENSATE FINNED TUBES STEAM IN

TYPICAL TANK HEATERS

STRAIGHT STAIRWAY

ROOF ACCESS STAIRWAY

CIRCULAR STAIRWAY

15'-6" IN DIAMETER FOR TANKS LESS THAN NOT RECOMMENDED

PRIMARY CONTAINER

12"/300 MINIMUM COLUMNS CONCRETE SLAB

LOW TEMPERATURE TANK FOUNDATION WITH ELEVATED CONCRETE BASE

DWG. NO.: TFP8

SPREAD FOOTING SECONDARY CONTAINER

3'-0" 900 TANK BOTTOM HIGH POINT VARIES 12"/300 POINT OF SUPPORT 1"- THICK ASPHALTIC CONCRETE

COMPACTED GRANULAR FILL

COMPACTED FILL TANK PAD

12"/300 POINT OF SUPPORT RING WALL 12"/300 TANK BOTTOM 6"/150± GRANULAR CLASS I

COMPACTED STRUCTURAL FILL

TYPICAL RING WALL FOUNDATION

15"-18"/380-460 CURB

PUMPS INSIDE DYKED AREA

PIPE RACK OR SLEEPERS

CURBED AREA DYKE

ALTERNATE ROUTING

PUMPS OUTSIDE DYKED AREA

PIPE RACK

DYKE

PIPE RACK ALTERNATE LOCATION

SLEEPERS

PUMPS INSIDE CONCRETE DYKED AREA

CONCRETE DYKE

DYKE- PENETRATION SEAL

DWG. NO.: TFP14 PIPE SLEEVE SEAL PRODUCT LINE DYKE WALL

FLEXIBLE DYKE SEAL

PIPE SLEEVE INSULATION

PRODUCT LINE INSIDE DYKE WALL

STEEL STRAP

ALTERNATE PIPING LAYOUTS

DWG. NO.: TFP16 PUMPING ALTERNATIVE LAYOUT FOR FLEXIBILITY (TYPICAL ALTERNATIVES) TANK NOZZLE (TYPICAL) LAYOUT PREFERRED

TANK PIPING LAYOUT

ELEVATION SLEEPER PLAN TANK OPTIONAL EXPANSION LOOPS HEADERS SLEEPERS (TYP) B A C

(SEE VALVE ACCESS CATWALK TFP5)

CROSS SECTION OF PIPE WAY AND PUMPING TANKS PUMPING DEPRESSED SLEEPER ROADWAY PUMPING TANKS DYKE DYKE PIPE BRIDGE ALTERNATIVE PRIMARY TANK PIPE WAY

BURIED PUMP DISCHARGE ACCESS

BULLET-TANK PIPING LAYOUT

C PUMPS_L PRODUCT OUTLET CATWALK RELIFE VALVE

PLAN

ELEVATION

RELIFE VALVE TO ATMOSPHERE CATWALK LIQUID OUTLET

LIQUEFIED NATURAL GAS TANK LAYOUT

DWG. NO.: TFP20 VENT MAINTENANCE ACCESS _CATWALK RELIEF VALVE VACUUM BREAKERS CATWALK C PUMPS (4 NOS.)_L TANK ROOF JIB CRANE OPERATIONS PLATFORM PIPE TRESTLE STAIRWAY EARTHEN EMBANKMENT ACCESS ROAD PRESSURE TEMPERATURE INSTRUMENTS (TYP)

LIQUEFIED NATURAL GAS TANK

JIB CRANE OPERATIONS PLATFORM TRESTLE PROCESS PIPE BRIDGE SUPPORT PIPING UTILITY PIPING STEEL INNER TANK STEEL LINER PUMP FOOT VALVE INSULATION CONCRETE CONTAINMENT PUMP SHAFT STEEL ROOF EARTHEN EMBANKMENT

DWG. NO. : TFP22

TYPICAL FIRE WATER SYSTEM IN TANKAGE AREA

ROAD ROAD

ROAD ROAD

FIRE WATER SUPPLY

FIRE MONITOR

PROTECTION BERM

BULLET TANK BERM

PLAN

BERM BULLETS SLOPE

ELEVATION