SGLPG Technical Standard One Storage of LPG in Bulk (HSE-03-10)

8/18/2019 SGLPG Technical Standard One Storage of LPG in Bulk (HSE-03-10)

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© Shell International Petroleum Company Limited

The Storage of LPG

in Bulk at MarketingOperations and

Customers’ PremisesStandard 1

Version 2.0 March 2008

Uncontrolled When Printed


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The Storage of LPG in Bulk at MarketingOperations and Customers’ Premises

This document is an uncontrolled version of the Shell Gas (LPG) standard concerning the storage of LPG in bulk atmarketing operations and customers’ premises for use by all staff that prefer to print a copy than referring to thecontrolled version on the SWW. Readers are advised to consult the controlled SWW version to ensure they areusing the most recent edition of this document. The controlled version is on the Shell Gas (LPG) website at:

http://sww.shell.com/downstream/lpg/functions/hse/controlled_docs.html

AUTHORISATION FOR ISSUE

Approved by: Paul Merridan, Head of HSE and Technical, Shell Gas(LPG)

Authorised for issue by: Erwin Friederich, VP, Shell Gas (LPG)

Date: March 2008

REVISION HISTORY

September 1999 Version 1.0 Publication of the first version of the standard.

June 2002 Version 1.1 Re-issued with the SWW version as the controlleddocument. No changes introduced to the original text.

October 2002 Version 1.2 Re-issued as an “evergreen” document. No changesintroduced to the original text.

March 2008 Version 2.0 Separation distances now local regulatory withminimum distances compliant with NFPA 58. Mainrequirements for hazardous areas zoning now inStandard 7. Requirements for liquid withdrawal valvesadded. Changes to fire fighting requirements. Adviceon Written Schemes of Examination.

Significant changes made in this version appear in red, bold text and are further indicated by a line in theleft hand margin of the page. In addition, minor editorial changes may have been made, ither to correctgrammatical errors or to improve clarity; such changes are not highlighted.


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Contents 1. Introduction ........................................................................................................................................ 5

1.1 About this standard.................................................................................................................................... 5 1.2 Scope.......................................................................................................................................................... 5 1.3 LPG properties and hazards...................................................................................................................... 5

Chart 1: Propane & Butane Characteristics...................................................................................................... 6

1.4 Legal requirements.................................................................................................................................... 7 1.5 Basic principles.......................................................................................................................................... 7 1.6 Safety data sheets ..................................................................................................................................... 7

2. Tanks..................................................................................................................................................... 8 2.1 Location, grouping & separation................................................................................................................ 8

Chart 2 Separation Distance for Single Above-Ground Tanks......................................................................... 9 Chart 3: Separation distances - flammable liquids and LPG tanks .................................................................. 9 flammable liquids .............................................................................................................................................. 9 Chart 4:Separation distance - liquid oxygen and LPG tanks............................................................................ 9

2.2 Fire walls.................................................................................................................................................. 10 2.3 Design...................................................................................................................................................... 11

Chart 5: Developed pressure.........................................................................................................................12 2.4 Mounded & underground tanks ............................................................................................................... 12

2.5 Skid mounted and mobile tanks ..............................................................................................................13 2.6 Tanks on roofs ......................................................................................................................................... 13 2.7 Vacuum protection................................................................................................................................... 13 2.8 Identification and marking........................................................................................................................ 14 2.9 Destenched / odourless LPG................................................................................................................... 14

3. Tank fittings..................................................................................................................................15 3.1 General requirements.............................................................................................................................. 15 3.2 Pressure relief valves .............................................................................................................................. 15 3.3 Drain Connections ................................................................................................................................... 16 3.4 Liquid withdrawal connections................................................................................................................. 16 1.1 ....................................................................................................................................................................... 16 3.5 Contents gauges...................................................................................................................................... 16 3.6 Filling connections ................................................................................................................................... 17 3.7 Service valves.......................................................................................................................................... 17 3.8 Emergency shut down valves.................................................................................................................. 17 3.9 High and low pressure alarms................................................................................................................. 18 3.10 Electrostatic precautions...................................................................................................................... 18 3.11 Lightning protection.............................................................................................................................. 18

4. Pumps, compressors and vaporisers ........................................................... 19 4.1 Pumps...................................................................................................................................................... 19 4.2 Compressors ........................................................................................................................................... 19 4.3 Vaporisers................................................................................................................................................ 19

5. Pipework and pressure regulators ................................................................... 21 5.1 Pipework.................................................................................................................................................. 21 5.2 Pressure regulators ................................................................................................................................. 22 5.3 Identification and marking........................................................................................................................ 23

6.1 Zone classification ................................................................................................................................... 24 7. Security ............................................................................................................................................. 25

7.1 General .................................................................................................................................................... 25 7.2 Preventing damage by vehicles............................................................................................................... 25

8. Fire precautions ...................................................................................................................... 26 8.1 General .................................................................................................................................................... 26 8.2 Fire protection.......................................................................................................................................... 26 8.3 Other installations where fire protection is required ................................................................................ 27 8.4 Portable fire fighting equipment............................................................................................................... 28

Chart 7: Fire precautions summary ..............................................................................................................28


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THE STORAGE OF LPG IN BULK AT MARKETING OPERATIONS UNCONTROLLED WHEN PRINTEDAND CUSTOMERS’ PREMISESVERSION 2

DATE ISSUED: March 2008 Page 4 of 39

DOCUMENT REFERENCE: HSE-03-10 © Shell International Petroleum Company Limited

9. Transfer operations.......................................................................................................... 29 9.1 General.................................................................................................................................................. 29 9.2 Road tanker loading / unloading ........................................................................................................... 29 9.3 Rail tanker loading / unloading.............................................................................................................. 30

10. Commissioning and de-commissioning............................................... 32 10.1 General.................................................................................................................................................. 32 10.2 Commissioning...................................................................................................................................... 32 10.3 De-commissioning................................................................................................................................. 32 10.4 Certification ........................................................................................................................................... 32

11. Training ....................................................................................................................................... 33 11.1 General.................................................................................................................................................. 33 11.2 Fire instruction and training................................................................................................................... 33

12. Written operating and emergency procedures............................ 34 12.1 Operations............................................................................................................................................. 34 12.2 Customer sites ...................................................................................................................................... 34

13. Maintenance and examination ....................................................................... 35 13.1 General.................................................................................................................................................. 35

Appendix 1 – Written Scheme of Examination.......................................... 36 Appendix 2 - Definitions ........................................................................................................ 38 Appendix 3 – References.................................................................................................... 39


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1. Introduction

1.1 About this standard

1.1.1 This standard describes general safe practice inhandling and storing LPG (liquefied petroleum

gas) in bulk at fixed installations for Shell Groupmarketing operations who store and use LPG. Itis applicable to commercial, industrial anddomestic installations. The standard is designedfor marketing operations installations, and if theinstallation forms part of a shared facility such asa fuels depot or a refinery then additional factorsmay need to be considered.

This version of the standard replaces Version1, which in turn superseded the previous ShellLPG Manual, Section 6, of February 1995.

1.1.2 The majority of the requirements of this standardare mandatory, that is to say, the requirementsmust be complied with without exception. Wherethe words “must”, “shall”, “requires” or “required”are used they imply a mandatory requirement.Except in the particular circumstances describedin 1.1.5 below, mandatory requirements must beconsidered the minimum standard that is to beapplied.

1.1.3 The requirements of this standard are notretrospective. From the date of issue of thestandard all existing installations must either:

Comply with the previous version of thestandard, or.

Comply with local legislation as applied to LPGinstallations (if local legislation does not exist theprevious version of this standard must be

applied), or

Comply with this standard

1.1.4 A transitional period of 12 months from the dateof issue of this standard is permitted. During thatperiod all new installations must comply with1.1.3 above. After the transitional period all newinstallations must comply with this standard.

1.1.5 The standard also contains optionalrequirements and recommendations on goodpractice. Optional requirements andrecommendations must be applied whenassessed as necessary for operational reasonsor where deemed necessary as a result of a risk

assessment carried out by a competent person.In general, optional requirements are explicitlyidentified as such within this standard; inaddition, where the word “should” is used, itimplies an optional requirement orrecommendation.

1.1.6 Deviation from the mandatory requirements ofthis standard will be considered in exceptionalcircumstances, that is to say, where existingpractices are demonstrated by a documentedrisk assessment to ensure that risks are being

managed by current practices to a level that is aslow as reasonably practicable. In such cases aformal derogation must be obtained inaccordance with the process described in thedocument ‘Process for Issuing Derogations fromShell Gas (LPG) Standards’ (HSE-03-50).

1.2 Scope

1.2.1 What this standard covers - This guide coversLPG storage at ambient temperatures in fixedcylindrical tanks with over 150 litres and up to135,000 litres individual water capacity, atcylinder filling plants, bulk distribution depotsand customer premises. It applies whether ornot the LPG is temporarily stored or stored foruse on site. It covers design, construction andinspection of LPG storage tanks plusprecautions for loading and unloading of roadand rail tankers.

1.2.2 What is not covered – This guide does notcover LPG cylinders or cartridges, transportabletanks, spheres or larger scale LPG storage orrefrigerated storage.

For advice on refrigerated or larger scale LPGstorage contact the Regional Operations andTechnical Manager (ROTM) or DIG/3.

The general principles of this standard applyto autogas installations. For specific Autogassite guidance refer to the Autogas InstallationDesign Guide which can be found on theShell Gas (LPG) website at:

http://sww.shell.com/downstream/lpg/functions/hse/uncontrolled_docs.html orcontact your ROTM or DIG/3.

Advice on the storage and use of LPG incylinders at depots, distributors’, dealers’,retailers’ and customers’ premises can befound in SGLPG Standards 2 and 3:http://sww.shell.com/downstream/lpg/functions/hse/controlled_docs.html .

1.3 LPG properties and hazards

1.3.1 Composition – LPG comprises CommercialPropane, Commercial Butane and mixturesthereof. They are hydrocarbon gases that canbe changed into a liquid and changed back intoa gas by the simple application and release of

pressure. (See Chart 1 for Propane andButane Characteristics).

1.3.2 Density - LPG vapour is at least 50% heavier than air and does not dissipate well. Beingheavier than air, it sinks when released andgathers in drains, pits, cellars and otherdepressions. As a colourless liquid, LPGoccupies around 0.4% of its vapour volume, butis about half the density of water and will floaton water before vaporising.


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1.3.3 Cooling effect – LPG vaporises and coolsrapidly; it can therefore inflict severe cold burnsif spilt on the skin or if some types of LPGequipment are touched without protectivegloves and goggles being worn.

1.3.4 Risk to breathing – LPG has an anaestheticeffect when mixed in high concentrations withair. The greater the concentration (i.e. asavailable oxygen declines), the greater the riskof suffocation.

1.3.5 Smell - What people know and recognise asthe ‘LPG smell’ is usually added to LPG beforedistribution. This smell must be detectable ifthe LPG content of air is as little as 0.4% (or just 20% of the lower limit of flammability).However, odour is not the only means ofdetection. Large leaks will also be obviousthrough hissing, condensation or frostingaround the leak; small leaks will show up asbubbles if detergent mixed with water is applied

to the suspected leak area. NEVER try to

detect leaks with a naked flame or otherkinds of ignition!

1.3.6 Flammability – LPG can ignite when it formsbetween 2 and 10% of a vapour / air mixture,so the risks associated with poor handling,storage or usage should be obvious.Uncontrolled ignition of LPG can cause seriousfires or explosions (i.e. if ignited within aconfined space). A fire started some distancefrom an LPG leak can very quickly travel backto the source of the leak itself. An LPG tankinvolved in a fire may overheat and ruptureviolently. The power and intensity of an LPGfire or explosion should never beunderestimated.

1.3.7 Empty tank risk – LPG tanks can bedangerous when they are nominally empty.This is because air can seep into them via anopen or leaking valve and mix with an LPGresidue to form a flammable vapour and anexplosion risk. At the same time, if a valve isleaking, or has been left open, the residue ofLPG can diffuse out of the tank into theimmediate storage area.

1.3.8 Expansion – LPG liquid has a high coefficient ofthermal expansion. Storage tanks, pipelines andequipment must be protected against the highpressure resulting from liquid expansion withtemperature rise.

CHART 1: PROPANE & BUTANE CHARACTERISTICS

PHYSICAL PROPERTY COMMERCIALPROPANE

COMMERCIALBUTANE

Litres / tonne of liquid at 15.6oC 1,957 – 2,019 1,723 – 1,760

Relative density (to water) of liquid at 15.6oC 0.50 - 0.51 0.57 - 0.58

Ratio of gas to liquid volume at 15.6oC and 1015.9 mbar 274 233

Relative density (to air) of vapour at 15.6oC and 1015.9 mbar 1.40 - 1.55 1.90 - 2.10

Volumes of gas/air mixture at lower limit of flammability from 1 volume

of liquid at 15.6oC and 1015.9 mbar

12,450 12,900

Boiling point oC -45 -2

Vapour pressure at 50oC psi g 283 100

bar g 19.6 7

Vapour pressure at 20oC psi g 130 40

bar g 9 2.5

Upper limit of flammability % V/V 10.0 9.0

Lower limit of flammability % V/V 2.2 1.8

Source: LP Gas Association (UK).


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Issued: September 1999 7 © Shell International Petroleum Company Limited

1.4 Legal requirements

1.4.1 In many countries most aspects of LPG storageare governed by some kind of national or locallegislation. All LPG storage owned by ShellGas (LPG) must, as a minimum, comply withthe national regulations. It is a duty of any

operator / owner of an LPG storage site toresearch and maintain knowledge of thelegislation which applies in their country andthen communicate this information to thoseinvolved in the management and operation ofsuch sites. Where the requirements of thisstandard exceed the requirements of nationalregulations, this standard must be applied.

1.5 Basic principles

1.5.1 Principles - The underlying basic principles forall bulk storage and its safe operation are:

Sound design and construction.

Consideration of usage of adjacent land and

property.

Good housekeeping.

Minimum stocks held.

Trained staff.

Minimum number of joints and potential leakpaths

Clearly displayed work instructions.

Non-combustible construction materials.

Clear of other flammables and combustibles etc.

Easy access.

Adequately separated from residentialaccommodation, commercial and industrialdevelopment, vulnerable populations, etc.

No cellars, open drains etc.

Open area with good ventilation.

Good security (vandalism and theft).

Access to authorised personnel only.

Clearly visible hazard/warning notices.

Emergency procedure and telephone numberdisplayed.

Appropriate fire fighting equipment.

No smoking or naked lights.

Appropriate electrical equipment for hazardousareas..

Safeguarding and mitigation systems.

Rigorous asset integrity regime in place

1.5.2 All equipment used in LPG service must besuitable for use with LPG, preferably typeapproved, meeting recognised standards andsuitable for all operating conditions theequipment is likely to encounter during itsservice life. All fire safe, fail safe orelectrical equipment and pipework must be

procured with relevant material certificateswhich must be kept as a matter of record.

1.6 Safety data sheets

1.6.1 Information - Safety data sheets incorporatingthe following information must be madeavailable to employees covering the range ofsubstances used e.g. jointing compounds,paint, lubricants and cleaning materials etc.:

Identification.

Composition.

Hazards.

First aid measures.

Fire fighting measures.

Accidental release measures.

Handling and storage.

Exposure controls/Personal protection.

Physical and chemical properties.

Stability/Reactivity.

Toxicological information.

Ecological information.

Disposal considerations.

Transport information.

Regulatory information.

Other information.

1.6.2 Availability - The following Shell Group safetydata sheets are available from DIG/3:

Commercial propane – SDS No. DMC04022

Commercial butane – SDS No. DMC04023/24

Safety data sheets for other products must beobtained from the supplier.


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2. Tanks

2.1 Location, grouping & separation

2.1.1 General – In considering location and separationdistances the principle must be considered that a

well designed and operated installation isunlikely to create a hazard. Separationdistances are measured from the surface of thevessel to any building or property boundary.They are provided to reduce the impact of anincident and current research indicates that therisks to the immediate surroundings from an LPGtank are from a gas cloud or jet flame. Gooddesign can substantially reduce these risks byreducing the potential leak points and ensuringthat all leak sources can be rapidly shut down inthe event of an incident. The worst casescenario for an LPG tank is the BLEVE (BoilingLiquid Expanding Vapour Explosion) and this canonly occur when the tank has a jet flame directlyimpinging on it or when the tank is engulfed in a

pool fire. Again, good design, where nopipework joints or equipment are located where afailure could result in a jet flame impinging on thetank or a pool fire occurring under the tank, willachieve significant risk reduction. This standardprovides separation distances for LPG storagefrom boundaries and buildings (chart 2)flammable liquids storage (chart 3) and liquidoxygen storage (chart 4) for an LPG storagequantity up to 120 tonnes

2.1.2 Locate above ground tanks in the open airaccording to the separation distances required inlocal legislation, but with a minimum separationdistance as listed in Chart 2. If local legislationdoes not exist apply the separation distances inChart 2. Ensure that there is a good airflowaround the tank. Where more than one vessel isinstalled they must be separated by a distance of¼ of the sum of the diameters of adjacentvessels with a minimum distance of 1 metre.Locate mounded or underground tanks in a waythat maximises the ventilation around thepressure relief valves and manhole, according tothe separation distances required in locallegislation, but with a minimum separationdistance of 3 metres from any vessel fitting and aminimum distance of 1 metre between vessels. All separation distances in Chart 2 are based ontank installations that are fully compliant with thisstandard with the minimum of joints and flanges

in pipework and a rigorous asset integritymanagement regime applied.

2.1.3 The ground underneath or next to connectionsinto LPG tanks or LPG ancillary equipment mustbe concreted or compacted and free from

depressions, pits, culverts or drains. Never site LPG tanks on top of each other. If allconnections are grouped at one end of the tank,it may only be necessary to compact or concreteunder the connections

The ground inside the required separationdistances must be substantially level and as flatas possible (except under the tank where it mustbe sloped away approximately 1:50 such thatany spillage of LPG can evaporate and dispersesafely in an area not under the tank).

Care must be taken to avoid siting tanks inlocations where the surrounding ground slopestowards vulnerable features e.g. other tanks,buildings, houses, drains etc., even though thesemay be outside normal separation distances.

Adjacent tanks must be spaced according to

specific site conditions and what is necessary forsafe installation, testing, maintenance andremoval.

If the frequency of delivery to a customer’spremises is high e.g. autogas or fork lift truckinstallation, consideration must be given toincreasing the separation distances and/orproviding additional fire protection.

2.1.4 Screening – If trees or shrubs are planted toscreen LPG tanks, they must not obstructairflow, i.e. locate them only on one side of thetanks. See 2.1.3 for guidance on larger tanks.Take care to plan too for:

The eventual size of the trees/shrubs.

The capacity of tree roots to interfere withunderground pipes, foundations or concretefootings.

The chance of tree branches breaking off in highwinds and falling onto the tank or associatedpipes and fittings.

Access needs for maintenance purposes.

.

2.1.5 Flammable Material - Remove any long grass,weeds, deciduous trees or shrubs and trees plusany combustible material from within 3 m of any2,500 litre water capacity or smaller LPG tankand within 6m of larger tanks. Never use sodiumchlorate or other chemicals which present a fire

risk to clear weeds near LPG tanks


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CHART 2 SEPARATION DISTANCE FOR SINGLE ABOVE-GROUND TANKS

Tank Water Capacity (litres) Minimum SeparationDistance to a Building,Boundary orPermanent Source of

Ignition

Notes

0-7600 3.0 1,2

7601- 114000- 7.5 1,3

114001-265000 23 1

265001 upwards Perform full riskassessment

Note 1 Based on NFPA 58 Liquefied Petroleum Gas Code, by the National Fire Protection Association. This edition of NFPA58 wasapproved as an American National Standard on January 16, 2004. Table 6.3.1 refers to minimum separation distances and thecolumn for aboveground containers is used here.

Note 2 In NFPA 58 this separation distance is modified by par 6.3.3 to the distance shown in chart 2 where the tank is at least 7.6 metresfrom another tank, otherwise tanks from 1900-7600 litres capacity must have a separation distance of 7.6 metres from a

boundary etc.

Note 3 In NFPA 58 this separation distance is modified by par 6.3.2 to the distance shown in chart 2 where the integrity of the tank conformsto this standard

CHART 3: SEPARATION DISTANCES - FLAMMABLE LIQUIDS AND LPG TANKS

FLAMMABLE LIQUIDS MINIMUM SEPARATION DISTANCE

Flashpoint less than 32oC 6 m to bund wall

Flashpoint 32oC to 65oC

Tank size up to 3,000 litre

Separation distance for LPG tank or 3 m to the tank/bundwhich ever is the lesser.

Flashpoint 32oC to 65oC

Tank size over 3,000 litre

3 m to bund wall or diversion wall and 6 m to tank.

CHART 4:SEPARATION DISTANCE - LIQUID OXYGEN AND LPG TANKS

LPG TANK WATER CAPACITY LPG TANK NOMINALCAPACITY

LIQUID OXYGEN CAPACITY SEPARATION DISTANCE

up to 265,000 litres Up to 60 tonnes Up to 566,000 litres 6 m

up to 4,500 litres

from 4,500 to 265,000 litres

Up to 2 tonnes

2 to 120 tonnes

More than 566,000 litres

More than 566,000 litres

7.6 m

15 m

Above 265,000 litres Above 120 tonnes All capacities Perform full risk

assessment

Note: from NFPA 58 Table 6.4.5.8

.


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2.1.6 Spillage planning – LPG spillage containmente.g. evaporation areas) must be installed for:

Propane tanks of 56,250 litres water capacity orgreater, with connections below the liquid level,unless plugged or blanked off.

Butane tanks of 11,250 litres water capacity orgreater, with connections below the liquid level,

unless plugged or blanked off.

Spillage containment areas must be safelysited away from boundaries, occupied buildingsand ignition sources. The ground below thetank and its connections must slope and becompacted or concreted so as to avoid pools ofliquid building up and to direct escaping LPG tothe safe evaporation area which must never becloser to LPG tanks than 3 m. Low walls(usually 500 mm or less) can also act as aneffective channel.

2.1.7 Natural phenomena – Local rules must beapplied to safeguard against naturalphenomena, including:

Lightning – Protection is not usually needed intemperate countries, but may be required intropical countries or those with a high frequencyof lightning strikes.

Earthquakes – Supports and foundations mustmeet local design requirements.

Flooding – Try to avoid siting tanks where thereis a known flood risk. Prevent flotation bysecurely anchoring tanks. Underground tanksmust be securely anchored where there is a highwater table.

Hurricanes – Where prevalent, consideration must begiven to the effect of high wind loading.

2.1.8 Bunded enclosures – LPG tanks must not besited inside the bunded enclosure of tanksholding:

Any flammable liquid.

Heated liquids such as heavy fuel or bitumen.

Liquid oxygen or cryogenic substances.

Or any other hazardous substance.

2.1.9 Siting cylinders near to tanks – In general,LPG cylinders must not be stored close to bulktanks to avoid any unnecessary restrictions toaccess. However, if it is necessary for overridingsecurity reasons or a bulk reserve supply forshort-term use, then these conditions apply:

Less than 50 kg may be stored adjacent to thetank.

If storing cylinders with horizontally ventingPRVS with a total quantity in excess of 50 kg –separate by 7.5 m from tanks of over 5,000 litreswater capacity or 3 m from tanks below this size.

If storing vertically venting cylinders (e.g. forforklift trucks) – separate by at least 1m from thetank and do not exceed 300 kg stored this closeto the tank.

2.1.10 Separation from cylinder filling plant – WhenLPG or other flammable liquid cylinders are filledin structures or buildings close to LPG tanks thefollowing separation distances must apply:

10 m from above ground tanks

5 m from underground tanks.

These distances do not apply if the quantity ofLPG in cylinders is less than 300 kg (e.g. fork lifttruck supply).

2.1.11 Horizontal tank direction – Where possible,arrange horizontal LPG tanks so that they are inparallel and do not point towards other tankscontaining dangerous substances, nearbyoccupied buildings or important equipment

2.1.12 Tank numbers – Not more than 6 above groundLPG tanks must be in a single group. Any tank inone group must be separated from the nearesttank in another group by the separation distanceto a public place in Chart 2.1, unless a fire wall isbuilt between the two groups. Within a group oftanks the distance between adjacent tanks mustbe (D1 + D2)/4 where D is the diameter of thevessel, with a minimum separation distance of1.5 metres.

2.1.13 Overhead electric power cables – LPG tanks,vaporisers, pumps and gas/air mixing plant etc.must not be located directly beneath electricalpower cables. LPG tanks must be sited:

At least 1.5 m from a line drawn vertically downfrom a cable carrying less than 1 kV.

This distance must be increased to 7.5 m forcables carrying 1 kV or more.

Or a competent engineer, usually from the localelectricity supplier judges each installation on itsown merits.

2.1.14 Flammable Liquids – Tanks containinga

flammable liquid with a flashpoint of 65oC or lessmust be sited not less than the separationdistances given in Chart 3.

2.1.15 Liquid oxygen / other dangerous substances – LPG and liquid oxygen tanks must be sitedaccording to the separation distances in Chart 4.Separate LPG tanks from other tanks holdingtoxic or dangerous liquids stored under pressureby at least 15 m.

2.2 Fire walls

2.2.1 Purpose – Fire walls shield the public andother vulnerable equipment from thermalradiation caused by fire and ensure anadequate vapour dispersion distance toboundaries, buildings and sources of ignition inthe event of an LPG leak occurring. They alsoenable the use of shorter separation distancesthan would be normally possible.

2.2.2 Siting – Fire walls must not be used on more


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than two sides or where the ventilation wouldbe impaired and normally only be used on oneside of a tank or tank grouping. In exceptionalcircumstances fire walls may be used alongone long side and two short sides of a tankinstallation if a risk assessment shows thatmeasures have been taken to bring the risk to As Low As Reasonably Practicable (ALARP)

Also:

They must be sited no closer than 1.5m from thenearest point of the tank.

Separation distances may be reduced to thedistance around the ends of the fire wall to apublic place as defined in Chart 2.

A fire wall for a tank up to 2,500 lit re watercapacity may form part of a building.

2.2.3 Construction – Fire walls must be solid,without any openings and made of brick,concrete or other suitable non – combustiblematerial. They must also be:

Capable of resisting fire for 60 minutes.

Totally within the boundary of the LPG storagearea.

For tanks up to 2,500 litres water capacity, ashigh as the top of the tank or highest piece ofhigh pressure or liquid pipework or fittingconnected directly to the tank and may form partof a building or site boundary

For tanks over 2,500 litres water capacity, atleast 2 m high or as high as the top of the tank,or highest piece of high pressure or liquidpipework or fitting connected directly to the tank,whichever is the greater

2.3 Design

2.3.1 Standards – LPG tanks must be designed,

manufactured, inspected and tested inaccordance with a recognised design code.Specifically they must comply with or exceedthe following:

Where tanks will be used for both butane ,propane and mixtures thereof at different times,the standards shown for propane must befollowed EXCEPT for minimum safe operatingpressure, which must follow the butanerecommendation.

Welded steel construction. Cylindrical with semi-ellipsoidal or hemispherical ends.

A hinged, lockable hood on tanks up to 2,500litres water capacity to protect fittings.

There should be no thickness allowance for

corrosion.

Steel used for construction of the tank must haveproperties suitable, particularly with regard toimpact resistance for operation over a range oftemperatures between – 20

oC and 50

oC.

Designed to safely contain the vapour pressureof the contained product at the assessedtemperature for the location where the tank willbe installed, and dependent on the reflectivity ofthe tank.

Above ground tanks must be painted a light

colour, preferably white, to increase reflectionand minimise the temperature rise of thecontents from solar heat gain.

In determining the maximum design safeoperating pressure, the assessed temperaturewill either be established by national and/or localregulations or by the design code for the locationor Chart 5 can be used for guidance for tanks

which are painted white. If the product to be contained in the tank is

butane and the atmospheric temperature at itsintended site may fall below zero then the tankmust be capable of withstanding negativepressure. See 2.7 for protection against vacuumconditions.

2.3.2 Filling capacity - The maximum quantity ofLPG which must be filled into any tank must besuch that the tank will not become liquid fulldue to expansion of its contents to theassessed temperature.

2.3.3 Corrosion protection – The tank and tanksupports must be adequately protected against

corrosion by zinc metal spraying and painting,after suitable preparation such as grit blastingor chemical treatment. Any form of corrosionprotection must allow for tankexpansion/contraction occurring with changes intemperature and internal vapour pressure. Attention must be given to the protection of theinternal faces of flanges and flange studs/boltsagainst corrosion.

2.3.4 Tank supports – Design for tank supportsmust comply with the relevant tank constructioncode of practice. In particular, supports must:

Allow the tank to move within the range oftemperature change.

Permit the drainage of any water.

Located (for horizontal tanks) to give minimumdeflections and moments to the tank shell.

Be reinforced with extra supports whereappropriate.

Supports may not be necessary forunderground tanks, but may be required whereit is necessary to anchor the tank because ofpotential flotation.Tanks must be installed on structural steel,concrete or brick supports, with solidfoundations. Supports must be fire resistant toa standard of at least 2 hours (except 460mmhigh or smaller feet, tank saddles or skirts for

vertical tanks). The supports must be ofsufficient strength to support the tank when fullof water.

Vertical tanks must have an open supportstructure that encourages effective airflow andprovides explosion relief. Where cylindricalsupporting skirts are used, pipes from the tankwithin the skirt must have welded or weldedflanged joints.

If piers form part of the supports for horizontal


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tanks of over 5,000 litres water capacity, allowone end of the tank to be free to move – butsecure the end to which the main liquid andvapour pipework is joined. Supports such assaddles must be welded to and form an integralpart of the tank.

2.3.5 Documentation - Detailed records of all tanks

must be held indefinitely and include:

Design specification.

Test certificates.

Approvals.

As built drawings.

2.3.6 Summary –The mechanical integrity of an LPG

tank cannot be guaranteed unless it complieswith the approved design standards and reflectsthe intended usage i.e. environmental conditions,process needs, vacuum and low temperatureuse etc.

CHART 5: DEVELOPED PRESSURE

LOCATION TANK WATERCAPACITY LITRES

ASSESSEDTEMPERATURE

OC

DEVELOPED PRESSURE (WHITE TANKS)BAR GAUGE

Butane PropaneTemperate climates 7,000 5.5 15

Tropical climates 7,000 6.2 17

Desert climates 7,000 6 19

Note: In practice many tanks are manufactured to standard design pressures.

2.4 Mounded & underground tanks

2.4.1 Separation distances - Mounded (partiallyburied) and underground (totally buried) tanks,

may in certain circumstances have reducedseparation distances and relief valve capacity,due to their inherent safety.

2.4.2 Design – Horizontal, cylindrical tanks must beused, designed, fabricated, inspected andtested in accordance with a recognisedpressure vessel code. Consideration must begiven to the additional stress caused by thepressure of the covering and any othersuperimposed load such as differentialsettlement etc.The design of mounded and large undergroundtanks must reflect the installation and operatingconditions detailed in this Section. Specialrequirements for small (primarily domestic)

underground tanks are shown at the end of theSection.

2.4.3 Location – Mounded and underground tanksmust be located in ground that is well drainedand not prone to flooding.

2.4.4 Covering – Mounded tanks must be coveredand underground tanks back-filled with amaterial that is:

Inert and non-corrosive.

Non-abrasive and free of particles likely todamage the tank coating.

Resistant to thermal radiation.

A consistent minimum of 300 mm in depth (whencompacted) for tanks up to 13,000 litres watercapacity. For larger tanks this must be increasedto 500 mm.

Robust enough to resist jet flame impingement.

In the case of underground tanks protected by animpact resistant coating to a relevant standard,some of the earth removed to install the tankmay be used to back-fill the installation..

The area above the tank may be turfed orcovered in shingle.

2.4.5 Installation – This must include:

A solid foundation for the tank, protected fromscouring and erosion by storm waters and

flooding. Underground tanks may be placed inexcavated ground without additional addedfoundations where ground conditions areappropriate.

Measures to avoid flotation or movement.

Excavation large enough to allow for easyinstallation and a gap of at least 1m between thetank and the walls before back-filling.

2.4.6 Inspection – A manhole of minimum 575 mminternal diameter must be fitted to mounded


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and underground tanks to provide access forinspection. If this is not done, it may benecessary to excavate the tank wheninspection is due (when tank fittings areattached directly to the tank and not via amanhole).

2.4.7 Corrosion protection – This must include:

A suitable system of cathodic protection (typicallysacrificial anode for small installations andimpressed current for large installations. Appropriate current and voltage readings mustbe taken periodically, recorded and analysed toensure that the condition of the vessel iseffectively monitored

External surfaces of the tank suitably preparedand treated with a coating manufactured andapplied in accordance with a recognisedstandard, to both protect against chemical andmechanical damage and minimise cathodicprotection current drain..

Avoidance of damage to the tank coating duringinstallation, use of fault detection equipment tocheck that the coating is intact and rectification of

any damage before back-filling is completed.

2.4.8 Small tanks – Special requirements for tanksbelow 5,000 litres water capacity are asfollows:

Manhole to facilitate internal periodicinspection is not needed, provided acathodic protection system is fitted andthe effectiveness of the protection ismonitored and recorded at intervals nolonger than a year. If the effectiveness ofthe cathodic protection is proved tocontinue to be satisfactory themaintenance interval may extended andthe tank may remain in serviceunderground for up to 20 years.

Locate such that vehicular traffic does notpass over underground tanks, unless aload bearing structure has beenconstructed to prevent any load beingtransferred to the tank.

May be installed in open ground withoutsupports on a bed of sand or othersuitable material provided that account istaken of the need to avoid unevenstressing of the tank shell and flotationand movement.

Means of removing liquid product must belocated in the top section of the tank, withan internal pipe to the bottom of the tank.

Protective valve cover need not have ahole for relief valve discharge.

2.5 Skid mounted and mobile tanks

2.5.1 Skid mounted tanks - Normally fixed in astatic frame e.g. ISO frame, for ease oftransportation and installation.

2.5.2 Mobile tanks - Normally mounted on their ownwheels or a trailer and must be designed andoperated in accordance with road transportspecifications. In no circumstances must a

mobile tank incorporating a tank designed forstatic use be used for delivery operations.

2.5.3 Separation distances - Comply with the fixedtank separation distances in Chart 2 for all skidmounted and mobile tanks. Preference must begiven to fixed tank installations, as skidmounted and mobile tanks are not as safe,being temporary and uncontrolled in nature.

2.6 Tanks on roofs

2.6.1 Preclusion - This practice is not acceptablebecause of the inherent hazards/high risksassociated with fire, leakage and access.

2.7 Vacuum protection

2.7.1 Vacuum creation - In colder climates duringextended cold weather, the contents of an LPGtank can drop below 0

oC. In some tanks – e.g.

those holding an LPG composition such ascommercial butane – the vapour pressureinside the tank would then fall belowatmospheric pressure, creating a vacuum,which could cause the tank to fail unless it hadbeen designed for vacuum operation.

2.7.2 Vacuum prevention - Tanks must be designedto an appropriate vacuum rating (applicable tonew tanks), or the system must be such thatunacceptable vacuum conditions can not occurin the tank (applicable to existing tanks). Acompetent person must check existing tanks toensure compliance with these standards.

If deficiencies are found, the tanks affectedmust be modified, or one of the following

vacuum prevention systems adopted withadequate safeguards:

Propane vapour pressurisation - the tank’svapour space is linked with the vapour space inanother propane tank or propane cylinders (viaappropriate double stage regulators where thetank is butane pressure rated).

Hot vapour return – warm LPG vapour isrecycled from a vaporiser to the tanks vapourspace.

LPG composition modification – the LPG supplieragrees to modify the regulated composition ofthe butane so that the vapour pressure at thelowest operating temperature is above the tanksminimum safe operating pressure.


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2.8 Identification and marking

2.8.1 Purpose – Any identification and markingmust:

Highlight the hazard associated with theproduct.

Prevent confusion at any time during normaloperations or an emergency, which may eitherprecipitate or aggravate an incident.

To do so it must be clear and durable, usingtags or plates securely fixed to the part to whichit relates, or directly marked on it. Never usepaper labelling.

2.8.2 Stamping – Stamp markings onto tanks mustonly be permitted in accordance with the designcode. Any other stamping must be on tanksupports, providing their integrity will not be affected by the stamping process and if themarking will remain legible after over-paintingor general wear and tear.

2.8.3 Specific information – If not a design coderequirement already make sure the followingspecific information is:

Available in tank documentation:

− Maximum acceptable load on tanksupports.

− Maximum acceptable LPG contents.

Plated on the tank:

− Serial number.

− Manufacturing date.

− Manufacturer’s identity.

− Design code.

− Water capacity.

− Minimum safe operating pressure (If notatmospheric – assume atmospheric ifnothing marked).

− Maximum safe operating pressure.

− Test pressure.

− Date of pressure test.

− Minimum safe operating temperature.

− Maximum safe operating temperature.

− Inspection authority.

2.8.4 Signs – Mark the tank clearly with ‘LiquefiedPetroleum Gas’ or, if there is any risk ofconfusion, a more detailed description of tankcontents; the words ‘Highly Flammable’ or asuitable visual symbol must also be added.

Emergency contact telephone numbers mustbe displayed or readily available at customersites.

2.9 Destenched / odourless LPG

2.9.1 Special precautions - These are needed whenLPG is supplied or used after destenching orwith a low odour. e.g. For use in aerosols as apressurising agent.

2.9.2 Additional measures - The following additionalmeasures must be taken:

Clearly mark tanks to indicate contents aredestenched or odourless.

Fit pressure gauges to all tanks.

Identify pipework as carrying odourless products.

Where practicable pipework must be welded andflanged.

Provision of sampling points, drain connectionsand means of isolating plant sections wherequality is a consideration.

Filling connections on the tank installation anddelivery vehicle hose end must have left handscrew threads or alternative distinctly differentconnections to those used for stenched product,to prevent the delivery of odourless product intostenched storage or vice versa.

A competent person familiar with the productmust carry out regular visual inspections for

leaks. Gas detection.


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3. Tank fittings

3.1 General requirements

3.1.1 Every tank must have at least one of each ofthe following:

A pressure relief valve directly connected to thevapour space and usually used in conjunctionwith a suitable automatic shut-off valve to enableremoval for testing and servicing. No otherfittings to be positioned between the PRV andthe tank.

A drain connection, or some other way ofdraining liquid from the tank.

A maximum liquid level indicator and,normally, a contents gauge. Where both areinstalled they must be independent of each other.

A filling connection.

A service outlet connection(s) for vapourand/or liquid duty if required.

A vacuum prevention measure wherenecessary.

A pressure gauge connected directly to thetank’s vapour space for tanks over 5,000 litreswater capacity or valved tapping in the vapourspace or adjacent pipework for smaller tanks.

A temperature gauge may be required if stockreconciliation has to be carried out.

3.1.2 Suitability – Fittings used in LPG tanks mustbe designed to cope with the pressures andtemperatures that will occur in service.Minimising direct connections (ideally, only one,excluding drain lines) below liquid level to lowerthe risk of leaks. All other connections mustterminate in the vapour space.

3.2 Pressure relief valves

3.2.1 General – All above ground tanks must befitted with one or more pressure relief valves, incompliance with a recognised code of practice,which will protect the tank in the event of a fire.

The setting and sizing of the pressure reliefvalve(s) must protect the tank fromoverpressure of more than 120% of the designpressure, which could be generated under fireexposure conditions.

3.2.2 Markings – Permanently mark each valve

with:

The certified capacity in terms of air at 15.6oC

and 1 bar pressure.

The manufacturer’s name and reference (i.e.type or catalogue reference).

The pressure at which the relief valve starts todischarge.

The date when it was last set or inspected.

3.2.3 Underground tanks – On mounded or

underground tanks, the full flow capacity ofpressure relief valves may be reduced to avalue that can be shown to adequately protectthe tank. Calculation of this value must also

consider whether the relief valves are requiredto prevent overpressure of the tank byoverfilling and may therefore require a capacityto relieve liquid LPG at the maximum fillingrate.

3.2.4 Isolation check valves – Care must be takento ensure that the design and certifieddischarge capacity of pressure relief valves arenot restricted by the introduction of checkvalves etc. which may be used to facilitateexchange whilst the tank remains in service, i.e.the relief valve(s) may have to have morecapacity than that calculated without the check-valve in order to deliver the correct amount ofLPG when a check-valve is used (seek

manufacturer’s data for flow reduction).

Manual isolation valves must not be fittedbetween the tank vapour space and a singlepressure relief valve.

With single relief valves – Install an automaticshut-off valve to allow for the removal of the reliefvalve for servicing / testing to take place; thismust be fully ‘open’ when the relief valve is inplace and ‘closed’ before the relief valve isremoved. The tank must never be leftunprotected and a replacement relief valve mustbe fitted immediately.

Where multiple pressure relief valves are fittedwith provision to allow for the removal andservicing of individual pressure relief valves, the

remaining pressure relief valves must haveadequate capacity to provide full protection forthe tank.

3.2.5 Vent pipes – Vent pipes must be fitted to thepressure relief valves on above-ground tanksover 1,500 mm internal diameter and greaterthan 5,000 litre water capacity. Specifically:

Vent pipes must be designed to prevent ignitedLPG flames impinging on the tank, pipework,equipment or nearby tanks.

Vent pipes must be adequately supported, withoutlets at least 1.8 m above the tank to whichthey are fitted.

Vent pipes must be carefully designed to avoidthe risk of mechanical damage to the reliefvalve(s).

Vent pipes must be protected against corrosionand be fitted with loose-fit rain caps, withprovision for water drainage.

Vent pipes may need protection in high windareas.


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gauge in addition to the mandatory fixed liquidlevel device

3.5.4 Tanks above 5,000 litre water capacity - Willnormally be equipped with a contents gaugewhich may be a simple magnetic float gauge,capacitance gauge or rotary gauge etc., inaddition to a fixed liquid level gauge.

3.5.5 Slip tube gauges - These are notrecommended and must be replaced when thetank is next gas free..

3.5.6 Sight glasses - Must not be used as a methodof measuring LPG liquid level in tanks and mustbe withdrawn from service immediately if foundon an LPG vessel.

3.6 Filling connections

3.6.1 Direct connection - Tanks must be equippedwith a liquid fill connection, which connectsdirectly with the vapour space of the tank. The

filling connection must be positioned for easyaccess to connect the filling gun. It is preferableon larger vessels for the liquid fill connection toenter vessel at a convenient point for filling viaa welded boss and internal pipe to the vapourspace. This removes the need to drag a hoseup access steps.

3.6.2 Spray filling - The internal discharge from fillconnections must form a liquid spray in thevapour space of the tank to facilitate rapidtransfer. Such arrangements must be designedwith care to avoid liquid spray entering thevapour service connections.

3.6.3 Manual shut-off - The filling connection mustbe equipped with a manual shut- off valve andautomatic back check valve. On tanks below5000 litres capacity where a manual shut-offvalve is not fitted, the delivery tanker shall usea filling gun adaptor with an additional back-check valve. If the automatic filler valve on thevessel fails to close, the adaptor on the end ofthe filling gun can be left in place and capped toseal off the leakage until the valve on the tankcan be replaced. The road tanker musttherefore carry a spare adaptor if it is tocontinue making deliveries to similarly equippedtanks.

3.6.4 Thread type - The liquid fill coupling must

normally be Right Hand Acme threaded forcommercial grades of odorised LPG.

3.6.5 Vapour balance - Vapour balance connectionsare not recommended for metered customerdeliveries, but they may be used for internaldepot transfers etc.

3.6.6 Adapters - Filling systems must be designedand installed to avoid the use of adaptersduring normal operations.

3.7 Service valves

3.7.1 Requirement - All tank vapour and liquidservice outlet connections must have aservice/isolation valve, except where pressurerelief valves are fitted or tank connections are

less than 1.5 mm in diameter. They must besuitable for LPG and be fitted directly to thetank or immediately after the first flange.

3.7.2 Protection - Vapour connections greater than8 mm diameter and liquid connections(including drains) greater than 3 mm diametermust be protected with an excess flow valve,non return valve or a remotely operatedemergency shut down valve.

3.7.3 Multivalves - Vapour service valves on smalltanks (typically up to and including 9,000 litrewater capacity) may be incorporated in eitherindividual or combination brass multivalves.

3.7.4 Liquid service valves - Shall be fire safe,quick acting ball valves. For tanks up to andincluding 9,000 litre water capacity aspecifically designed LPG liquid offtake valveincorporating an excess flow valve may beused.

3.8 Emergency shut down valves

3.8.1 Type – Emergency shut down (ESD) valvesare remotely operated, positive, fail closed,shut-off valves, used to isolate tanks andsections of piping/equipment in emergencysituations.

3.8.2 Automatic operation - ESD valves shouldpreferably be actuated automatically, e.g. by afusible link in the energy supply to the actuator,by the plant alarm system and/or gas detectionsystem, or by manual control. They shouldpreferably be pneumatically actuated anddesigned to operate in a controlled manner (notsnap action) to avoid pressure surges whichcould lift hydrostatic relief valves, or on openingcause inadvertent operation of excess flowvalves etc.

3.8.3 Installation - ESD valves must be installed inall liquid service connections from tanks havinga nominal internal diameter greater than 25 mmand where:

There are routine LPG depot operations such ascylinder filling and tanker transfer activities, or

The public has unrestricted access to the activitye.g. hospitals or school, or

Where there are people not familiar with theemergency procedures and prompt evacuationwould be difficult e.g. retail autogas and fork lifttruck facilities.

Consideration must be given to installing ESD


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valves in smaller sized liquid services or evenvapour services at strategic points in criticallocations such as cylinder filling plants toensure overall emergency control.

3.8.4 Location - Careful attention must be given tothe location of the remote controls for ESDvalves, and to the number of ESD valvesincluded in a single shut-down system. Forexample, in a small depot or customerinstallation it may be considered safer toinclude all ESD valves in a single system, suchthat all ESD valves in the system are closedsimultaneously, whereas in other plants it maybe necessary to use several ESD systems.

3.8.5 The shutdown controls shall be located atvarious positions over the site and shall beclearly indicated with an appropriate notice. Thelocation of the controls for opening ESD valveswill depend on the manner in which the plant issupervised and operated, but the number ofpositions from which the ESD valves can be

activated shall be limited to the minimumrequired for safe operation.

3.8.6 Automatic trip - The shutdown system designmust include automatic trips on the LPG pumpsactivated by ESD valve closure. The closure ofESD valves must be automatically linked to theemergency alarm and water fire protectionsystem.

3.8.7 Manual override - ESD valves must not beprovided with hand wheels or operating levers,unless there are specific local requirements toprovide manual override. A notice warning ofremote actuation must be located on or nearany valve with a manual override facility.

3.9 High and low pressure alarms

3.9.1 Use - Alarms may be fitted to monitor:

Abnormally low tank pressure; possible fault inthe pressure control apparatus.

The effectiveness of a vacuum protectionsystem.

Abnormally high tank pressure.

3.9.2 Setting - Low-pressure alarms must be setabove the tank’s minimum safe operatingpressure.

High-pressure alarms must be set below thetank’s pressure relief valve setting. These areoften used to trigger integrated water sprays.

3.9.3 Sensor location - The pressure sensors inhigh and low-pressure alarms must measure atank’s vapour pressure. Using pressuresensors in pipework may not give a truereading of the tank pressure.

3.10 Electrostatic precautions

3.10.1 Provision must be made to ensure that noelectrostatic potential exists between the tankerdelivery connection and the static tank fillconnection which could generate a spark whenthe connection is made, or broken.

3.10.2 The following must apply:

All tanks except those whose capacity does notexceed 2,500 litres water capacity, must bepermanently bonded to an effective groundedearthing point to prevent any build up of anystatic electricity. The earthing point must besituated so that it is readily available for thetanker to discharge any static electricity bymeans of its earthing cable before the deliveryhose connection is made.

For tanks up to and including 2,500 litres watercapacity, a bonding connection may be providedon the tank to allow the direct attachment of thetanker earthing/bonding cable before making thedelivery hose connection.

Underground tanks which are not fitted withcathodic protection require an earthing rod.

Underground tanks which are fitted with cathodicprotection and do not require an earthing rodmust have a bonding connection on the tank toallow direct connection by the delivery vehicleearthing lead.

3.10.3 There must be electrical continuity between thetank transfer connection(s) and the earthingpoint or bonding connection, through the tank.Earthing or bonding connections must alwaysbe kept clean, unpainted and free fromcorrosion to ensure a good electricalconnection.

3.10.4 At LPG depots, the interlinking of a permissivesystem to tanker bonding, where transfer ofLPG can not take place until bonding iscontinuous, is recommended.

3.10.5 Earthing points must have low electricalresistance to earth and never greater than 1 x10

6ohms to ensure the satisfactory dissipation

of static electricity.

3.11 Lightning protection

3.11.1 Lightning protection is often not required onLPG tanks, but local requirements must bechecked and applied, particularly in respect of

vertical tanks.


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4.3.2 Types – There are five basic types ofvaporiser, all of which must be capable ofvaporising LPG at the maximum offtake rateneeded from the installation:

Low pressure steam-heated.

Hot water heated.

Electrically heated.

Direct gas fired (This type of vaporiser must notbe used and must be removed if present at thenext major inspection period for the installation).

Atmospheric.

4.3.3 Design and materials – Vaporisers mustcomply with the following requirements:

Heat exchangers must be designed andconstructed in accordance with an approvedpressure vessel code.

The design pressure must be not less than 17bar or the set pressure of the relief valvewhichever is the greater. In all cases the designpressure must be at least that of the LPG liquidinstallation.

Shell and tubes in contact with LPG must be ofsteel.

The design of hot water and steam units mustensure that there is no risk of water (or steamcondensate) freezing during periods of highofftake or low ambient temperature conditions.

The vaporiser capacity must be not less than thatrequired for the conversion of liquid to vapour ata temperature above dew point at the maximumfirst stage regulator inlet pressure and maximumofftake rate.

The vaporiser and all piping components andrelief valve up to and including the dischargevalve must be designed for the same conditionsas the inlet pipework.

4.3.4 Precautions – Precautions must be taken:

To prevent the accumulation of condensate in allpipelines carrying LPG vapour. This may take theform of insulation or heat tracing. Drain potsmust be provided and all horizontal pipe runsmust incline slightly rising away from thevaporiser so that any condensate runs back to a

drain pot.

To avoid freezing of the steam condensate orwater associated with steam or hot watervaporisers.

4.3.5 Markings – If not a design code requirementalready, the following information must bemarked on vaporisers (via metal plate orincluded in easily accessible documentation):

Minimum and maximum safe operatingtemperature.

Maximum safe operating pressure.

The serial number and manufacturer.

Year of manufacture.

The design code it complies with.

4.3.6 Location - Vaporisers must be sited such thatthe minimum distance from the nearestimportant building or line of property is asfollows:

3 m up to 36 kg/h capacity.

7.5 m from 37 to 227 kg/h capacity.

15 m over 227 kg/h capacity.

Vaporisers may be mounted on the wall of abuilding if it can be considered to be a fire wall,with a defined fire resistance and no openings.


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5. Pipework and pressure regulators

5.1 Pipework

5.1.1 Design – Pipework and fittings must complywith the relevant standards and be of a

material suitable for LPG, the proposedconditions of service and the extremes ofpressure and temperature likely to beencountered.The number of joints in pipework must beminimised. In steel pipework over 50mmnominal bore it is particularly important tominimise the number of flanges. Pipeworkmust be welded where possible and flangesmust never be orientated in a position wherethe failure of a gasket could result in an ignitedleakage causing a jet flame to impinge on anLPG tank or other pressurised equipment. Inaddition remember that one release if ignitedmay cause a cascade effect by impinging onanother fitting and eliminate this possibility by

good design.

5.1.2 Materials - Materials commonly in use are:

Carbon steel – Seamless pipe to an acceptablethickness or galvanised heavy/medium weightwelded seam pipe. All carbon steel pipeworkused at vapour pressure or in liquid service mustbe accompanied by a national certificate whichmust be retained with the installation records.Similarly, any welding must be carried out bycertified welders to an appropriate code andrecords maintained.

Copper - Half – hard or annealed solid drawncopper. The risks of work hardening must beconsidered. Not suitable for pipework carryingliquid LPG.

Polyethylene (PE) - This type of pipe, if to asuitable standard, can be used for LPG vapourand LPG/air mixtures, providing it is mostlyburied. In general, medium density PE is suitablefor use with LPG vapour at pressures up to 4 barand a temperature range of - 20

oC to 40

oC.

Corrugated Stainless Steel – Proprietarybrands of flexible stainless steel pipe may beused for underground liquid LPG service at Retailforecourts and similar installations.

5.1.3 Types of pipework – These include pipework:

To carry vapour below 5 bar. Carbon steel,copper up to 35 mm diameter or PE may be usedunderground.

To carry vapour at full tank pressure i.e. above 5bar. Seamless carbon steel to an acceptablethickness or copper up to 15 mm diameter maybe used.

To carry liquid. Seamless carbon steel to anacceptable thickness must be used.

Over 50 mm nominal bore. Seamless carbonsteel to an acceptable thickness must be used.

5.1.4 Types of fittings – These include:

Screwed joints may be used for pipework with anoutside diameter of 50mm or less.

Welded or flanged joints (except when attachingto equipment with screw fittings) must be used

for outside diameters greater than 50 mm andmust be of an appropriate class and be raisedface weld neck type.. Spiral wound graphite filledmetal gaskets (ASME B16.20) must be used forflanges in pipework carrying liquid LPG. It mustbe noted that on established installations gasketsmay be made of compressed asbestos fibres andappropriate PPE must be worn when breaking joints. Jointing compounds for screwedconnections, flanged gaskets and any othercomponent parts must be suitable for use withLPG.

Heat fusion or mechanically jointed fittings maybe used for copper or polyethylene pipe. Thelatter must be designed to resist the pipe pullingout.

5.1.5 Installation – Pipework must be routed aboveground and in the open air where practicable. Itmay be buried underground providing it isinherently resistant to corrosion. e.g.polyethylene or adequately protected bycathodic protection, bitumen/tar wraps,impregnated tape etc.

5.1.6 Supports - The design, spacing and fixing ofsupports must be:

Appropriate for the configuration of the pipes

Capable of resisting guide friction and anchorageforces.

5.1.7 Routing - The routing of piping must be

designed to minimise pipe contents andthereby reduce the potential hazard. Thechosen pipe route must:

Minimise risks of vehicle damage (e.g. avoid siteroads or protect with bollards).

Preferably run above ground.

Avoid or protect from extremes of cold or heat.

Avoid running through buildings if carrying liquidLPG or vapour pressure above the nationalstandard low-pressure. Where this is impractical,pipe length must be minimised, protected fromphysical damage and ventilation around the pipemaximised within the building.

5.1.8 Electrical continuity - Piping must be

electrically continuous so that the resistance to earth of the installation does not exceed 10

6

ohms in order to avoid the build-up of staticelectricity. Achieving a value of no more than100 ohms should not be difficult and, unless thepipes suffer significant corrosion, this is unlikelyto degrade over time to levels above 10

6 ohms.

It is not usually necessary to bridge flanges withbonding straps to achieve an acceptable levelof continuity, however it may be necessary tobridge certain types of valve with a bonding


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strap to obtain continuity.

Pipelines, fittings and hoses used for liquidphase LPG transfer must have electricalcontinuity and be reliably connected to earth. Itmay be necessary to fit electrical bondingstraps across connecting joints.

Ball valves must not disrupt electrical continuityin the pipeline.

More detailed information on static electricitymay be found in national standards, Institute ofPetroleum Codes, etc.

5.1.9 Flexible connections - Flexible connectionsmust be suitable for the required duty andcomply with a relevant design code. In addition:

They must also be as short as practicable andused only where necessary.

Where used for conveying liquid, the internalpressure in hoses must be restricted by ahydrostatic relief valve to the lower of the fixed

pipe operating pressure or the design maximumfor the hose.

Emergency isolation in the form of an excessflow valve, remotely operated valve or non –return valve must be fitted to prevent the risk ofLPG leaking from a failed hose.

5.1.10 Above ground PE pipework – Where PEterminals are brought above ground at tanks orpremises, the exposed pipework must beshielded from mechanical or ultra – violetdamage by sleeving, and normally limited to nomore than 2m and in any case as short aspracticable. Alternatively, a suitable fitting maybe used below ground to achieve the transitionto metal pipework on either or both terminal

transitions.

5.1.11 Underground pipework - Pipework buried inan open trench, which is back-filled with non-corrosive material must meet the followingrequirements:

Backfill must contain no abrasive and potentiallydamaging particles.

For metal pipes anti-corrosion measures mustbe used, e.g. cathodic protection, bitumen / taroverwraps, proprietary wax impregnated tapeetc.

In general underground liquid or tank pressurepipework must be avoided. Where this isunavoidable, pipework must be protected from

vehicular loading by installing either load-bearingcovers or exclusion fencing. Pipework must berun in a shallow brick or concrete lined trenchcovered with open grids where appropriate forsafe pedestrian access.

Design must compensate for any extra constraintor loading or constraint due to backfill orunderground siting.

Where any kind of superimposed load mayoccur, the pipe affected must be protected withcovers or well-supported load-bearing slabs.

Isolation valves must be fitted at both ends ofthe underground length of pipe.

Pipes carrying flammable or inert liquids may belaid in the same trench but NOT pipes carryingtoxic or corrosive materials.

Do not run in the same trench as electric cablesunless an outer sleeve or pipe insulates them.

Electrical cables must be separated at least 300mm from LPG pipework.

Where cathodic protection is used on LPGpipework seek specialist advice from DIG/5.

A plan must be made to record the pipe layoutand, if possible, permanently mark the routeabove ground

5.1.12 Pipework used to carry liquid or vapour attank pressure:

Must be well supported and installed.

Either load-bearing covers or exclusion fencingmust be installed. Pipework must be run in ashallow brick or concrete lined trench coveredwith open grids where appropriate for safe

pedestrian access. As an alternative to using a brick or concrete-

lined trench, liquid-containing pipe may be runinside an outer ‘sleeve’ pipe. Ensuring that this issealed at both ends (with at least one endaccessible for inspection) and the space betweeninner and outer pipes is monitored for leaks (e.g.by detecting pressure changes).

Hydrostatic relief valves must be fitted in anypipework in which liquid LPG may be trapped(e.g. between shut – off valves) to protect againstexcessive pressure. Where possible do not fitthese valves beneath tanks. Valves fitted undertanks must not allow LPG to escape across thetank surface or nearby access points. Atmospheric discharges must be to the open airand must not pose any danger to life or

equipment. Where possible hydrostatic reliefvalves must be orientated to discharge upwardsto maximise dispersion of the LPG vapour.

5.2 Pressure regulators

5.2.1 Specification – Pressure regulators controlwide variations in tank pressure and deliver therequired outlet pressure despite a variable gasflow caused by intermittent use.

5.2.2 Types – There are three basic types ofregulators:

First stage (high–pressure) – Designed toreduce vapour supply pressure to the required

intermediate high pressure. Used as a firststage regulator in a two-stage system or wherea high outlet pressure is required.

Second stage (low-pressure) - Designed toreduce intermediate pressure to the requiredfinal operating pressure.

Single-stage - Designed to reduce vapourpressure down to final operating pressure in asingle stage.

Although single-stage, low-pressure regulatorshave been used in some countries with bulk


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6. Hazardous area classification for electrical equipment

6.1 Zone classification

6.1.1 SGLPG Standard 7 covers the requirement tomanage potential explosion risk from LPG at:

Cylinder Filling Plants

Rail tanker loading and unloading.facilities

Ship and barge loading and unloading facilities

Road tranker loading and unloading facilities

Cylinder storage facilities such as dealers,distributors or stockists.

Terminals and depots including all storage andtransfer facilities

At all other sites including domesticinstallations, commercial installations such asrestaurants, hotels, factories and LPG fuellinglocations, local regulations will apply toinstallation of electrical equipment. Where localregulations do not exist, no electrical equipmentshall be installed within 2.5 metres of any LPGfilling point, connection point, fixed ullagegauge, pump, compressor, vaporiser or reliefvalve unless it complies with the requirementsof Standard 7 par. 4.1.3.1 for a zone 1.

Appropriate measures must be taken to ensurethat equipment that might provide a source ofignition is not within the hazardous zone duringconnection and disconnection of LPG supplies,or maintenance work involving the opening ofany part of the LPG system.


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8. Fire precautions

8.1 General

8.1.1 Principles – Minimise major fire risks(including escalation) through installation

design, layout and resourcing that bothcomplies with all relevant local legislation andcodes of practice, and specifically optimises:

Best practice in engineering.

The implementation and enforcement of sound operating procedures.

Emergency procedures.

Staff training (both routine and emergencyprocedures).

Location of water supplies.

Location and marking of shut-off valves.

Access, protection and equipment for firefighters.

Contingency plans and drills for fire incidents.

Arrangements to call fire brigade promptly in theevent of a fire.

Prevention or shutdown of any release of LPG isthe most effective way of controlling an incident

8.1.2 Responsibility – Where the local fire authorityis responsible for organising, equipping andmaintaining a fire brigade and managing firefighting operations, any fire which may threatenstored LPG must be attended by the firebrigade, who will take control of fire fightingoperations on arrival, even if they involve sitefire teams in their efforts.

8.1.3 Planning – The local fire authority may want to

be involved in the planning of any new LPGstorage facilities; if, during planning, furtherguidance on fire precautions is needed andcannot be found in this standard, consult theenforcing authority (see definitions).

8.1.4 Access – All sites must at all times beaccessible without hindrance to fire fighters.

8.2 Fire protection

8.2.1 General – The most effective form of fireprotection is for there to be no release of LPGor if a release occurs, to detect it immediatelyand shut it down. The use of gas and fire

detection and shutdown systems musttherefore be strongly considered where a riskassessment indicates that this approach wouldbring the risk to ALARP. It must be noted thatsuch systems can only be effective if a rigorousregime of maintenance and testing is in placeand their reliability can be demonstrated fromcomprehensive records.

8.2.2 Research and subsequent advice from ShellGlobal Solutions regarding fire protection of

LPG tanks once a fire is in progress has led tothe following conclusions:

The only sources of heat that threaten theintegrity of an LPG tank are jet flames or

pool fires

Water sprays are ineffective against a jetflame and only a suitably positioned firewater monitor will deflect the jet flame fromthe surface of a tank

Good design will significantly reduce theprobability of a pool fire engulfing a tank,by directing any LPG spillage away frombeneath the tank.

Fires adjacent to an LPG tank which do notengulf the tank in flames are unlikely tocause failure of the tank, however

increased pressure

SGLPG Technical Standard One Storage of LPG in Bulk (HSE-03-10)

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