acetic acidbulk storage of

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1. INTRODUCTION 2

2. COMMERCIAL ASPECTS OF BULK STORAGE 2

3. TECHNICAL ASPECTS OF BULK STORAGE 3

4. LOCATION OF STORAGE TANKS 3

5. TANKER DISCHARGE 3

6. DESIGN AND CONSTRUCTION OF TANKS 4

7. LEVEL MEASUREMENT 4

8. PIPEWORK 5

9. VALVES 6

10. PUMPS 6

11. HEATING FACILITIES 6

12. PRE-COMMISSIONING 7

13. ACID DILUTION 7

14. LABELLING AND SAFETY PRECAUTIONS 8

15. PRODUCT TRAINING 8

16. OPERATING PROCEDURES 9

17. FURTHER TECHNICAL LITERATURE 9

Appendix 1 Key Safety and Environmental Data of Acetic Acid 10

Appendix 2 Typical Weights and Dimensions of Fully Laden Road Tankers 10

Appendix 3 Diagram of Typical Above Ground Storage Installation 11

Appendix 4 Diagram of Typical Above Ground Fixed Roof Storage Installation 12

Appendix 5 Diagram of Typical Under Ground Storage Installation 13

Appendix 6 Suitable Fittings for Tank Inlet Connections 14

Appendix 7 Suitable Materials for Seals, Gaskets and Hoses 14

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1. INTRODUCTION

1.1 This technical booklet has been produced forthe guidance of customers who are interested ininstalling bulk storage facilities for acetic acid. Itdescribes in general terms the requirements for asuitable installation.

1.2 Our experience has shown that the design andconstruction of each bulk storage installationrequires individual consideration, because of thenature of the site, the users specific requirementsand the impact on any existing facilities in thevicinity. BP offers a Technical Advisory Service, freeof charge, to customers who wish to make use of it.We consider that our Technical Advisory Service ismost useful to a customer when discussions areheld at the earliest possible stage and certainlybefore the design of the unit has been finalised. Ourlocal Sales Representative will be pleased to makethe necessary arrangements.

1.3 The storage and handling of corrosive andflammable liquids is subject to legislative controls inmany countries. Customers are recommended toobtain and make themselves familiar with anyrelevant regulations and keep abreast of newregulations, as and when these apply. Informationcontained in this booklet is not intended to replaceany legal requirements which may be applicable tothe storage and handling of acetic acid in particularcircumstances. It is recommended however, that theguidance outlined in this technical booklet isfollowed, provided that it does not conflict with anyspecific legal obligations.

1.4 A Material Safety Data Sheet has been issueddescribing the health, safety and environmentalproperties of acetic acid, identifying the potentialhazards and giving advice on handling precautionsand emergency procedures. This must be consultedand fully understood before handling, storage or use.Key safety and environmental data are listed inAppendix 1.

2. COMMERCIAL ASPECTS OF BULKSTORAGE

2.1 Although acetic acid can be supplied inpackages, for example nominal 210 litre drums, it isoften more convenient for the customer to receivebulk supplies. Bulk storage is more compact thanstorage in drums and therefore releases space andhandling equipment for other duties. Stock control isalso made easier and deliveries can be received lessfrequently. There may be cost savings from reducedhandling. The time taken to recover the capital cost

of the bulk installation will depend upon its size andthe rate at which the acetic acid is used.

2.2 Acetic acid is available in bulk from BP in fourgrades as follows: Chemically Pure Acetic Acid,99.5% Technical, 80% Pure, and 80% Technical.

2.3 When small quantities of aqueous acetic acidare required, it is usual to buy the appropriate dilutegrade, which is more convenient for handling.However, where large quantities are used,consideration should be given to the purchase of fullstrength acid in bulk which can be diluted to therequired strength following receipt. The initial capitaloutlay is higher, because of the additionalrequirement to provide mixing equipment, but this isoffset by the saving resulting from the lowerpurchase cost of the acid.

2.4 Bulk deliveries of BP’s acetic acid are normallymade by road tankers. Customers should carefullyconsider the optimum storage capacity for theinstallation, bearing in mind delivery load sizes aswell as current and estimated future usage.Adequate capacity should be provided to allow adelivery to be taken well before the previous supplyis exhausted and also to hold sufficient stock tomeet contingencies.

3. TECHNICAL ASPECTS OF BULKSTORAGE

3.1 Acetic acid is a corrosive and flammable andthus certain precautions are necessary if it is to bestored and handled safely. This can be achieved byensuring that the storage and handling facilities arecorrectly designed and constructed and that safeoperating procedures are followed.

3.2 Information on the design, construction andlocation of storage installations for acetic acidcontained in this booklet is applicable only if thetemperature of the liquid remains below 30°C. Athigher temperatures, different materials ofconstruction may be required.

3.3 The following aspects need to be considered forthe safe and efficient receipt and storage of aceticacid:

• Location of storage tanks

• Tanker discharge

• Design and construction of tanks

• Level measurement

• Pipework

• Valves

bulk storage of acetic acid

• Pumps

• Heating facilities

• Pre-commissioning

• Acid dilution

• Labelling and safety precautions

• Product training

• Operating procedures

3.4 These aspects are considered in detail in thefollowing sections.

4. LOCATION OF STORAGE TANKS

4.1 The arrangement and any grouping of tanksrequires careful consideration. It is important toconsider access not only for normal operations butalso for emergency evacuation.

4.2 The design of the tank farm should takeaccount of the likely consequences of anyaccidental spillage or fire. Products which reactchemically with acetic acid should be kept in totallysegregated storage.

4.3 Storage at ground level and in the open air ispreferable because in the unlikely event that a leakoccurs, it is more likely to be detected.Examination, modifications and repairs are alsoeasier and corrosion can be more readily identifiedand controlled. An exception to an outsideinstallation is where a small tank for glacial aceticacid can be conveniently installed in a buildingwhich is already heated thus removing the need forheating and insulating the tank.

4.4 Storage tanks should not be located:

a) on the roof of a building,

b) in an elevated position,

c) on top of each other,

4.5 Storage tanks should be discharged by pump.Horizontal tanks should be positioned just highenough above ground level to provide clearance forconvenient operation and maintenance of valves.

4.6 All tanks should be surrounded by a bund wall.The required capacity of the bund may be subject tolocal regulations. It should be equivalent to at least110% of the capacity of the largest tank within thebund. The walls and floor of the bund should beimpervious to liquid and designed to withstand a fullhydrostatic head. Bund walls should not be higherthan 1.5 metres in order to ensure adequate naturalventilation of the bunded areas, ready access forfire fighting and a good means of escape.

4.7 Intermediate lower bund walls arerecommended to divide tanks into groups to contain

small spillages and to minimise the surface area ofany spillage.

4.8 The floor of the bund should be sloped toprevent minor spillages remaining below any tank.Provision should be made for the removal ordrainage of surface water from the area within thebund. Surface water should preferably be pumpedout of bunds. If bund drains are used they shouldbe provided with valves outside the bund walls,with procedures in force to ensure these valvesremain closed, and preferably locked, except whendrainings are being removed.

5. TANKER DISCHARGE

5.1 The provision of vehicle access needs to betaken into account when selecting the site for thestorage installation. The following aspects need tobe considered:

a) a clear, safe access for the vehicle withsufficient room to manoeuvre to and from thedischarge point (this must allow the vehicle tobe driven forward from the unloading point inan emergency rather than being reversed),

b) the width, corners, type of surface and load-bearing capacities of the approach road,

c) headroom under any overhead gantries,

d) any bridge or other restrictions.

5.2 Typical weights of fully laden vehicles withdimensions and turning circle are shown in Appendix 2.

5.3 A trial run with an empty tanker may beappropriate if the access is doubtful.

The unloading point should be located facing thetanker’s outlet connection to avoid the need to runflexible hoses under or to the rear of the tankerwhen discharging. Ideally, only one short length offlexible hose should be used for the dischargeoperation.

5.4 Vehicles must not stand on a road or path usedby the public while being discharged and must be atleast 6 metres from a right of way. It is preferable ifthe immediate area surrounding the discharge pointis closed to all except those directly concerned withthe operation while tanker discharge is being carriedout.

5.5 It is good practice to provide an earthing pointnear the discharge point for connection to theearthing point on the road tanker.

5.6 The rate at which the discharge takes place isnormally about 600 litres per minute whether by thevehicle’s pump or compressor. This depends to

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some degree on the configuration of the pipework tothe storage tank. When the customer’s own pump isto be used, a similar rate should be planned.

5.7 Road tankers are fully insulated to prevent aceticacid freezing in cold weather.

5.8 During the road tanker discharge operation acidvapour will normally be displaced from the storagetank vent. If the presence of acid vapour in thedischarge area is unacceptable, the installation of asystem to return the vapour to the road tanker canbe considered. Further details can be obtained fromBP’s Technical Advisory Service.

6. DESIGN AND CONSTRUCTION OFTANKS

6.1 The storage tank must be of adequate strengthand capacity for the proposed duty.

The tank and its supports should be designed andconstructed in accordance with an appropriaterecognised standard of good engineering practice.

The choice of construction material for storage tanksdepends upon the grade of acid, and also on cost.

6.2 Tanks constructed from the following materialsare suitable for storing 80% acetic acid.

a) Stainless steel grades 304, 316 and 321

b) High density polyethylene (HDPE)

c) Polypropylene (PP)

d) Glass reinforced plastic (GRP) with either aHDPE or PP lining

e) Rubber lined carbon steel.

Increase in temperature can affect the mechanicalproperties of some plastics and care should be takento avoid overheating the tank contents.

6.3 Stainless steel of ASTM 316 or 321 grade orequivalent is suitable for the storage of all grades ofacetic acid.

6.4 Aluminium of minimum 99.5% purity is suitablefor the storage of glacial acetic acid, but any dilutionof the acid should not be allowed as this willaccelerate corrosion of the tank. The temperaturecontrol of the acid must be more precise whenaluminium is used rather than stainless steel, sinceabove 30°C the corrosion rate increases sharply, withthe formation of aluminium acetate.

6.5 The materials of construction described aboveare only suitable for acetic acid as delivered. Whereany process material is recycled to the storage tank,trace quantities of impurities may cause oraccelerate corrosion. Corrosion tests should becarried out using the recycle material.

7. LEVEL MEASUREMENT

7.1 Every tank should be provided with a suitablemeans of determining the volume of the contents. Acontents indicator is preferred to manual dipping.

The following types of contents indicator may beused:

a) Gauge glass

Gauge glasses of the reflex type may be used with80% acid.

They should be suitably protected on all sidesagainst shock damage and fitted with top andbottom isolating cocks. They are not suitable forglacial acid because of the difficulty of preventingfreezing in the gauge glass.

b) Hydrostatic gauge

Hydrostatic gauges provide a level measurementsystem requiring no external power source oradjustment. They are simple but robust inconstruction and require little maintenance. All metalparts of these instruments should be fabricated instainless steel of a suitable grade.

c) Pneumacator

This is a simple type of level indicator which isrelatively cheap but effective. Care should be takenthat all parts of the system are compatible withacetic acid. All metal parts of these instrumentsshould be fabricated in stainless steel of a suitablegrade.

d) Ultrasonic and radar level indicators

For higher accuracy in level measurement, ultrasonicand radar level indicators are available for use withacetic acid. Care should be taken to ensure that theyare intrinsically safe to BASEEFA (British ApprovalsService for Electrical Equipment in FlammableAtmospheres) standard SFA 3012 for Zone ‘O’ withcertified ‘Ex’ head units and probes, or to anequivalent standard.

7.2 Where manual dipping is necessary thefollowing precautions should be applied:

a) the tank should be fitted with a dip tubeextending down close to the bottom of the tank,with a wear pad welded to the tank bottombeneath the dip tube.

b) the top of the dip tube should have a vapourtight cap which should always be in positionexcept when gauging is actually taking place.

c) dip roads should be substantially smaller indiameter than the dip tube to reduce anyinaccuracy in measurement. Wooden orstainless steel dip rods can be used.

d) dipping should never take place through openmanholes.

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7.3 It is recommended that each tank should befitted with a high level alarm, the measuring elementof which should be independent from level indicator.An alarm operated from a float switch is suitable forthis purpose.

8. PIPEWORK

8.1 The general layout of pipelines directlyconnected to the tank is shown in Appendices 3, 4and 5. These should normally be of the samematerial as the tank, except for plastic tanks, whichshould have the inlet pipeline fabricated from asuitable grade of stainless steel.

8.2 The tanker hose connecting point (inletconnection) should be provided with a suitable fittingto connect to the delivery hose. Suitable fittings aredescribed in Appendix 6. The inlet connection shouldbe positioned as near as possible to where thevehicle will stand during discharge, and should beprotected from accidental damage. The inletconnection should be located at a convenient height,i.e., not more than 1 metre above ground level,facing outwards, for hose coupling. The inlet lineshould be fitted with an isolation valve as close aspossible to the inlet connection. When a number ofdifferent products are stored, each inlet connectionshould be clearly marked with the name of theproduct to which it relates. An inlet line of 80mmnominal bore is a suitable size for transferring aceticacid from the road tanker to the tank. The lineshould enter the top of the tank. The inlet should besloped towards the tank as shown in Appendix 3. Adrain cock should be fitted at the lowest point in theinlet line so that the line can be drained at thecompletion of tanker discharge. Space for a smallreceptacle (20 litres capacity) should be left underthis drain cock.

8.3 A tank discharge line should be provided whichshould be a minimum of 50mm nominal bore. Thedischarge line is usually taken through the bottom orthe side of the tank to an isolating valve.

This isolating valve should be located as close aspossible to the tank. In all cases, discharge shouldbe by pump. The pump and controls should be sitedoutside the bund.

8.4 If the tank discharge line is not located at thelowest point of the tank, a facility should be providedfor draining the tank. A 25mm nominal bore branchfitted at the lowest point of the tank is suggested.The branch should be fitted with a suitable isolatingvalve and blanked off when not in use.

8.5 A vent line needs to be provided, leading fromthe vapour space at the top of the tank, for thedispersion of vapour. This vent line should beconnected to the highest point of the tank and be as

far removed as possible from the inlet line. Toprevent possible damage to the tank, the vent lineshould not be smaller in diameter than either theinlet or the discharge lines.

It is good practice to connect the vent line to ascrubbing system. However, if no such system isavailable, it is recommended that the tank vent isextended down into the tank bund to within 200mmof the floor, to prevent injury to personnel fromwindborne droplets of acetic acid at the end of thedischarge. Free circulation of air around this vent isessential to disperse vapours, particularly while thattank is being filled. A vacuum break should beprovided on this vent line. This may be in the formof a tun dish, or be a small hole (6mm) drilled in thevent line above the level of the bund wall.

8.6 In order to reduce vapour emissions to theatmosphere it is possible that legislation will infuture require that bulk deliveries of acetic acid aremade using a vapour return system or a tank with avent scrubber. A typical vapour return system isshown in outline in Appendices 3 and 4. Vapoursdisplaced from the storage tank during deliverywould be transferred to the vapour space of thedelivering tanker.

8.7 Wherever possible, continuously weldedpipework should be used. However, where pipeworkmay have to be disconnected for maintenance orinspection, flanged joints should be fitted. Flangesconforming to the American National StandardsInstitute (ANSI) 150lb and PTFE envelope gasketsare recommended. Other suitable gasket materialsare shown in Appendix 7. Graphitised jointing pasteshould not be used with stainless steel.

8.8 A vapour tight manhole should be provided onall tanks to allow for internal inspection and cleaning.

8.9 An earthing point should be fitted on tankscontaining pure acetic acid, and this should beconnected to a good earth. The resistance to earthat any point of the installation should be less than 10ohms. This also applies to the tanker earthing pointwhich preferably should be connected to the sameearth, or if independent should have minimalresistance between this and the tank-pipeworksystem. It is good practice to fit an earthing point ontanks containing 80% acetic acid.

8.10 The pipework system should be designed suchthat liquid cannot be trapped between closed valveswithout some form of pressure relieving device. Thisapplies especially to heated pipework (see section11).

8.11 Joints in pipework should not be located overdoorways, windows or close to possible sources ofignition.

8.12 Pipework should be routed to minimise thepossibility of accidental damage.

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9. VALVES

9.1 Stainless steel ball or gate valves with PTFEseats are recommended for use with acetic acid andare suitable for all applications.

9.2 Plug or diaphragm valves can also be used withacetic acid. However, diaphragm valves should notbe used on the bottom outlets of tanks.

9.3 PVC or polypropylene ball valves can be usedfor 80% acetic acid.

10. PUMPS

10.1 Pumps should be located outside tank bunds,on an impervious base, in an open space, and not inwalled or confined spaces.

10.2 Pumps for 99.5% acetic acid should befabricated from a suitable grade of stainless steel,i.e. ASTM 316. Polypropylene may be used for 80%acetic acid.

10.3 Self-priming centrifugal pumps should be usedwherever possible. Mechanical seals with PTFEwedges (Crane Type 109 or equivalent) arerecommended for this duty but these seals mustnot be run dry. If packed glands are used, braidedPTFE should be used. If metering or otherreciprocating pumps are used, PTFE packing ispreferred. Glandless centrifugal pumps withmagnetic coupling may also be used.

10.4 Arrangements should be made to collect anyleakage from glands. Connections at the pumpshould be flanged to ANSI 150lb. Threaded jointsmust not be used.

10.5 When glacial acetic acid is being handled, it isnormal practice to drain a pump after use and toclose the isolating valves until it is required again.

10.6 If pumps can be remotely controlled, a stopbutton should be provided both at the pump, and atthe delivery point.

10.7 Suitable materials for use as seals and hosesare shown in Appendix 7.

11. HEATING FACILITIES

Introduction

11.1 In most situations it is necessary to takeprecautions, such as the provision of heating and/orinsulation, to prevent glacial grades of acetic acidfrom freezing in tanks and pipelines. These gradesfreeze at temperatures between 14°C and 16°C.

11.2 For 80% grades, the need for precautions tobe taken to prevent freezing of the acid will dependupon the location of the tank and local ambienttemperature conditions. 80% grades of acetic acidfreeze at -7°C. Consequently, in many cases specialprecautions are unnecessary.

Temperature control

11.3 If heating is provided, thermostatic temperaturecontrol is strongly recommended to ensure that thetemperature of the acetic acid does not exceed30°C. At higher temperatures the rate of corrosionof stainless steel by acetic acid increases andflammable mixtures of air and acetic acid arepossible. The fitting of low and high temperaturealarms is recommended.

11.4 Thermostatic control also ensures economy inthe usage of the heating medium and minimisesvent loses. The temperature sensing element for thetank should be installed in a 40 mm nominal borepocket at the side of the tank and which extendstowards the bottom of the tank at a point remotefrom the heating element. The thermometer pocketshould be of stainless steel, filled with oil. If heatingis by hot water or steam and instrument air isavailable, a simple pneumatic temperature indicatingcontroller will be adequate. If instrument air is notavailable a direct-acting controller must be used, anda direct reading temperature indicator should beinstalled.

11.5 With electric heating, a simple on/offthermostatic control switch will be adequate.

Heating of the storage tank

11.6 For glacial grades, the storage installationshould be designed to maintain the tank contents ata temperature of 25°C ± 5°C. If the tank is installedinside a building, provided the ambient temperatureis not allowed to fall below 20°C, no additionalmeans of heating is required. Precautions will stillhave to be taken to avoid freezing of the inlet andvent pipes if these pass outside the building.

11.7 If the tank is installed outside, an internalstainless steel (ASTM 316L) heating coil isrecommended. This may be heated by either hotwater or low pressure steam. Electric heating padscan be used but these should be designed so thatoverheating of the surface of the tank does notoccur.

11.8 In all cases where storage tanks are heated,they must also be effectively insulated.

Heating of pipework

11.9 The ratio of heating surface to liquid volume ismuch higher in pipework than in the storage tank.This means that acid in a pipe is much moresusceptible to overheating, if heat is applied, or tofreezing if the insulation is faulty. In view of this,some system of thermostatically controlled heatingon the pipework is recommended. Care must betaken to avoid high surface temperatures, as thesemight cause an increased rate of corrosion and

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consequent contamination of the acid.

11.10 Pipelines may be heated electrically or by hotwater. Electric heating tapes wrapped around thepipe or electric heating elements running along theunderside of the pipe may be used. When hot wateris available, a 15mm nominal bore mild steel traceline can be run directly below the acid line. Thetracing is supported by the acid line but smallspacing pads prevent direct contact. Maintenance issimplified if the trace line is jointed adjacent to theacid line joints. For pipelines in continuous serviceautomatic control must be used to avoidoverheating.

For occasional duties, such as the inlet line, steamheating may be used. The installation should besimilar to hot water heating, with steam traps at alllow points. The line should be drained after use andthe heating properly shut off. To ensure completedrainage the slope of the line should be increased to1 in 50.

It is most important that the vent line is fully traceheated and insulated to avoid blockage bycrystallised acetic acid vapour during cold weather.

Heating of pumps

11.11 Steam/water-jacketed pumps can be obtainedbut are not usually necessary. It is normally sufficientprotection if the pump is sited inside a warm buildingor if the heating element or tracing line is continuedaround the base of the pump.

Heating of valves

11.12 Steam/water-jacketed valves are expensiveand not readily available. It is normally adequate tocontinue the heating element or tracing line close tothe valve body.

Thermal insulation of tanks and lines

11.13 Heated tanks, pumps and pipelines should beinsulated to prevent heat losses and reduce heatingcosts. In addition, if the installation is sited outdoors,the insulation must be weatherproofed.

11.14 Preformed types of insulation arerecommended. Preformed slabs or mattresses maybe used with tanks, and preformed sections ofadequate bore for the pipelines plus heating devices.All flanges, valve bodies and pumps should beinsulated.

11.15 For tanks and pipework in stainless steel,chloride-free insulation must be used or corrosionwill result.

12. PRE-COMMISSIONING

12.1 When the bulk installation is completed it isnormal practice flush the whole system throughwith water to remove any debris. When this is doneit is advisable to:

a) fit fine wire mesh strainers at the inlets ofpumps and meters to prevent them beingdamaged by solids,

b) use water with a low chloride content i.e. below30ppm, to avoid any possibility of chloridecorrosion of the stainless steel.

12.2 Where a stainless steel tank is to be used, andthe iron content of the product is important, it isadvisable to condition the tank before use, toremove iron. BP will be pleased to advise onsuitable conditioning procedures.

13. ACID DILUTION

Introduction

13.1 Reference to price schedules will showwhether it is economic to buy glacial acid and diluteit with water down to the required strength. Thereare no major process difficulties and personnel soonbecome accustomed to the method of dilution andits control.

Water quality

13.2 All town water contain soluble salts, althoughsome waters are of a better, or softer, quality thanothers.

13.3 The quality of the diluted acid depends uponthe quality of the water used. For this reason, it isrecommended that for high grade 80% acetic aciddemineralised water or distillate is used as diluent.Filtered steam condensate may be used only if ithas not been in contact with mild steel equipment.However, not all customers require such a highgrade product. In such cases, ordinary towns watermay be used as diluent. However, it should be notedthat contaminants, e.g. chloride, can causeincreased corrosion in subsequent processing.

Dilution equipment

13.4 The dilution is normally carried out in the bulkstorage tank. The tank should be sized, therefore, tocontain the required delivery of acetic acid, plus thedilution water, plus any residue of diluted acid whichhad not been utilised. Acid and water are intimatelymixed using either a top entry agitator or a jet mixernozzle and pump. Jet mixing is normally the moreconvenient method. It is favoured by the basicgeometry of a storage tank and the cost can be less,particularly as a pump is usually required for otherpurposes.

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13.5 Jet mixing is simply the circulation of acid fromthe tank into a pump and back into the tank throughan inclined nozzle at the tank base. The jet of liquidfrom the nozzle produces the stirring action in thetank.

13.6 The nozzle design is critical, depending on thegeometry of the tank and the pump rating. OurTechnical Advisory Service engineers will, onrequest, advise on a jet mixing system for theproposed duty.

The nozzle should not be used until there is about1.5 metres of liquid above it. Mixing time is so shortthat this is not at all a serious disadvantage. Thetank should not be filled through the nozzle.

The inlet delivery line should be heat traced andinsulated.

Demineralised water

13.7 Where demineralised water is used for thedilution of acid, a tank should be installed for thestorage of the treated water. The economics ofwater treatment are such that it is cheaper to installa small capacity demineralising unit feeding over aprolonged period of time into a water storage tankrather than a large capacity unit feeding into the acidtank over a short period. Alternatively, the acid tankcan be filled slowly with water if not requiredcontinuously.

13.8 Demineralising equipment is supplied bymanufacturers specialising in this field and theiradvice should be sought regarding the most suitableunit for a specific application.

13.9 Demineralised water is corrosive to somematerials. Equipment such as the treated waterstorage tank should be of corrosion resistantmaterial. Stainless steel, ebonite-lined carbon steel,polyethylene or polypropylene may be used.

Method of dilution

13.10 It is recommended that initially up to 80% ofthe water required for dilution is added before theacid delivery. After the delivery, the tank can be jetmixed and the contents sampled. Measurement ofthe relative density of the liquid and its assay willgive the quantity of acid in the tank.

It is a simple matter to calculate the additional waterand to add the quantity required accurately. The tankis again jet mixed and the assay checked. As theoperator becomes more skilful in the technique ofdilution, the initial charge of water may be increasedto say 90%.

Calculation of dilution

13.11 For the dilution of 99.5% by mass acetic acidto 80% by mass:

W = 244.1 M

where W is the amount of water to be added inlitres and M is the amount of 99.5% acid in tonnes.

For different strengths the following equation maybe used:

W = M x (X - 80) x 125.2410

where X is the initial concentration of acetic acid,mass per cent, W is the amount of water to beadded in litres and M is the amount of acid intonnes. Thus, for X = 99% m/m

W = 1 x (99 - 80) x 125.24 litres per tonne10

= 19 x 125.2410

= 238.0 litres per tonne

14. LABELLING AND SAFETYPRECAUTIONS

14.1 The words:

ACETIC ACID – CORROSIVE TO SKIN

should be painted on all acetic acid bulk tanks.Emergency instructions, in case of splashing, shouldbe shown at the main places of work. An adequatenumber of eye baths or wash bottles containingwater (for use until a source of running water can beused) should be kept in the working area. Buckets ofsodium bicarbonate may also be kept in the workingarea for skin use only.

14.2 In addition, safety showers with a quick actingvalve, adequately protected against frost, or a waterbath should be installed on site. There should be anadequate supply of water for hosing down the areain the event of an acid spillage.

14.3 Buildings in which acetic acid is stored orhandled should be well ventilated.

15. PRODUCT TRAINING

All personnel associated with the handling of aceticacid should be fully trained to enable them tounderstand:

a) the nature of the potential hazards associatedwith the handling of acetic acid,

b) the appropriate storage and handlingprecautions including personal protectionmeasures,

c) the appropriate action to be taken in the eventof an emergency.

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16. OPERATING PROCEDURES

Written operating instructions should be available forthe receipt of acetic acid, and operating personnelshould be fully trained in their implementation. Theinstructions should take account of the specifichazards, and ensure the correct operation ofequipment in both normal and emergency situations.Key points of a typical discharge operation for bulkroad tankers are:

a) the customer's representative must ensure thatthere is sufficient ullage available in thereceiving tank to accept the nominated delivery.

b) prior to discharge, all appropriate safetyequipment must be checked and suitablypositioned.

c) only those personnel directly concerned withthe discharge operation should be in the area,with appropriate protective clothing being worn.

d) a customer’s representative must identify thedischarging point to be used, and the earthingpoint, and must supervise all connections to thevehicle.

e) the road tanker should be connected to theearthing point before the delivery hose isconnected. This earth must be maintainedthroughout the operation and not be brokenuntil after the hose is disconnected, oncompletion of product transfer.

f) during discharge, regular checks should becarried out to ensure that the load is beingreceived into the appropriate storage tank. Thecustomer's representative must remain inattendance throughout the discharge operation.

g) on completion of discharge, the pump (if used)should be stopped and the valves in the pipeline

closed. The drain cock adjacent to the inletvalve should then be opened carefully, to allowany product remaining in the inlet pipe to draininto a receptacle. Next, the hose should bedrained through the inlet valve and drain cockinto a receptacle (5 to 10 litres of drainings maybe expected). It is the customer’s responsibilityto provide adequate facilities for disposal ofthese hose drainings.

h) the delivery hose should be thoroughly washedthrough with water.

i) all equipment must be properly stowed beforethe road tanker is given authorisation to departfrom the discharge point.

j) finally, the quantity in the tank should bechecked against the amount expected. Dippingthe tank or removal of a sample for testingshould not take place until at least 30 secondsafter completion of discharge. This is to allowfor the relaxation of any electro-static chargewhich may have been generated in the transfer.

17. FURTHER TECHNICAL LITERATURE

17.1 Further technical literature on acetic acid isavailable from BP as follows:

a) BP Acetic Acid Product Specification andPhysical Properties.

b) Material Safety Data Sheet, giving health, safetyand environmental data.

Copies of Material Safety Data Sheets are normallysupplied automatically by our Sales Offices. Furthercopies are available either by direct request to theSales Office or by asking our local salesrepresentative to arrange for copies from the SalesOffice.

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APPENDIX 1 KEY SAFETY AND ENVIRONMENTAL DATA OF ACETIC ACID

Flash point (closed cup) Acetic acid chemically pure 39°C

Acetic acid 80% pure 65°C

Autoignition temperature 463°C

Freezing points Acetic acid chemically pure 16.6°C

Acetic acid 80% pure -7.0°C

Flammable limits in air lower 4.0% volume

upper 19.9% volume

Acetic acid is readily biodegradable in both fresh and salt water. It is slightly toxic to aquatic species, i.e. TLm96 10-100 ppm, but is unlikely to bio-accumulate.

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APPENDIX 2 TYPICAL WEIGHTS AND DIMENSIONS OF FULLY LADEN ROAD TANKERS

Nett weight 22 – 25 tonnes

Gross weight 38 – 44 tonnes

Overall length 13.5 – 15.5 metres

Overall height 4 metres

Overall width 2.5 metres

Turning circle 14 – 17 metres

Actual values will depend upon the vehicle design and construction regulations currently in force in the countryconcerned.

return to contents

11

APPENDIX 3 DIAGRAM OF TYPICAL ABOVE GROUND STORAGE INSTALLATION

Sin

gle

shor

t len

gth

of fl

exib

le h

ose

Pip

es to

be

seal

ed in

bund

wal

l

Tan

ker

eart

hing

with

bulld

og c

lipB

und

wal

lIm

perv

ious

bas

e

1 M

ax b

und

heig

ht 1

.5m

2 T

ank

heat

ing

will

be

requ

ired

for

glac

ial g

rade

s of

ace

tic a

cid

750

mm

appr

ox.

25m

mdr

ain

valv

e

65m

min

take

valv

e2½

" B

SP

mal

ein

let c

onne

ctio

n

prot

ectiv

eca

p an

dch

ain

Inta

ke p

oint

for

road

tank

er d

eliv

ery

Bun

d w

all

Sum

p

80m

m m

inim

umve

nt p

ipe

Fix

ed a

cces

sla

dder

Tan

k co

nten

ts to

be c

lear

lym

arke

d on

tank

Tan

kea

rthi

ng

Tan

k su

ppor

tsst

eel o

r co

ncre

te

1 m

min

600m

m m

anho

lew

ith b

olte

d co

ver Slo

pe

Slo

pe

LI

50m

mdr

ain

bran

ch

80m

m in

let l

ine

Slo

pe to

tank

Pro

duct

s to

be

clea

rly m

arke

dat

del

iver

y po

int

To

pum

p

50 m

mde

liver

y lin

e

50m

m b

all

valv

e

1 m

min

2m lo

ng c

omm

onco

pper

ear

thin

g ro

d

Pre

ssur

e/va

cuum

valv

e

LAH T

ank

insu

latio

n(g

laci

al g

rade

s)

Wat

er

Ven

tsc

rubb

er(a

ltern

ate

desi

gn)

38m

m v

apou

r re

turn

(whe

re fi

tted)

TI

Sho

wer

loca

ted

adja

cent

to s

tora

ge in

stal

latio

nin

corp

orat

ing

quic

k ac

ting

valv

e an

d ey

e-ba

th

Tow

n's

wat

er s

uppl

y

Wat

er h

ose

for

was

hing

dow

n

return to contents

LAH

150m

m m

in

Han

drai

ls

600m

m m

anho

le fi

tted

with

hing

ed e

mer

genc

y re

lief

hatc

h

pres

sure

/va

cuum

valv

e

50m

m d

ip p

ipe

with

scr

ewed

cap

loca

l to

stai

rs

Fix

ed a

cces

sst

airs

Tan

k co

nten

ts to

be c

lear

ly m

arke

don

tank

Pip

es to

be

seal

ed in

bund

wal

l

To

pum

p

Pum

p re

cycl

e

Mix

ing

nozz

le

Wea

rpl

ate

Slo

pe

Tan

kea

rthi

ng

Man

hole

38m

m v

apou

rre

turn

(w

here

fitte

d)

Pro

duct

to b

ecl

early

mar

ked

atde

liver

y po

int

Non

-ret

urn

valv

e

TI

Tan

ker

eart

hing

with

bulld

og c

lipB

und

wal

lS

umpSlo

pe

50m

mdr

ain

80m

m in

let l

ine

Sam

ple

poin

tB

und

wal

lC

omm

on e

arth

sys

tem

Impe

rvio

us b

ase

750m

map

prox

.

25m

mdr

ain

valv

e

65m

min

take

valv

e2½

inch

BS

Pm

ale

prot

ectiv

eca

p an

dch

ain

Inta

ke p

oint

for

road

tank

er d

eliv

ery

1 M

ax b

und

heig

ht 1

.5m

2 M

in b

und

wal

l to

tank

1m

3 T

ank

heat

ing

will

be

requ

ired

for

glac

ial g

rade

s of

ace

tic a

cid

Sin

gle

shor

t len

gths

of fl

exib

le h

ose

\`

Wat

er

Ven

tsc

rubb

er

LI

Tan

k in

sula

tion

(gla

cial

gra

des)

12

APPENDIX 4 DIAGRAM OF TYPICAL ABOVE GROUND FIXED ROOF STORAGEINSTALLATION

return to contents

13

Tan

ker

eart

hing

lead

with

bul

ldog

clip

Sin

gle

shor

t len

gths

of fl

exib

le h

ose

80m

m m

inim

um v

ent p

ipe

to s

afe

loca

tion

(to

be fi

tted

with

apr

essu

re r

elie

f sys

tem

if a

vap

our

retu

rn s

yste

m is

use

d)

50m

m s

uctio

n lin

e

To

pum

p

Tan

k an

d pi

pes

belo

w g

roun

d to

be

prot

ecte

d ag

ains

t ext

erna

l cor

rosi

on

Pit

back

fille

d w

ith d

rysa

nd

Tan

k su

ppor

tsst

eel o

r co

ncre

teW

ear

plat

e

Inle

t con

nect

ion

for

road

tank

er d

eliv

ery

80m

m fi

ll an

d di

p pi

pefit

ted

with

lock

able

cap

Pro

duct

and

vap

our

retu

rn, w

here

fitte

d, to

be

clea

rly m

arke

d at

del

iver

ypo

int

38m

m v

apou

rre

turn

(w

here

fitte

d)

Sea

led

to k

eep

out

wat

er Rei

nfor

ced

conc

rete

2m lo

ng c

omm

onco

pper

ear

thin

g ro

d

LI

Not

e: T

ank

reci

rcul

atio

n sy

stem

not

sho

wn

Fla

me

arre

stor

Tan

k ea

rthi

ng

APPENDIX 5 DIAGRAM OF TYPICAL UNDER GROUND STORAGE INSTALLATION

return to contents

14

UK: 2.5 inch BSP parallel threaded male connection

France: symmetric coupling NF-E 29.572, 80 mm nominaldiameter (type ‘Guillemin’ or equivalent)

Germany: quick coupling DIN 28450, 3 inch male connection

APPENDIX 6 SUITABLE FITTINGS FOR TANK INLET CONNECTIONS

APPENDIX 7 SUITABLE MATERIALS FOR SEALS, GASKETS AND HOSES

Seals Ethylene propylene rubber (EPDM)

‘Kalrez’

Butyl rubber

PTFE encapsulated

Gaskets PTFE envelope

EPDM

Butyl rubber

Hoses Polyethylene

Polypropylene

Stainless steel (316)

EPDM

Butyl rubber

PTFE

EXCLUSION OF LIABILITY

Information contained in this publication is accurate to the best of theknowledge of BP p.l.c.

Any information or advice obtained from BP otherwise than by means ofthis publication and whether relating to BP materials or other materials, isalso given in good faith. However, it remains at all times, the responsibilityof the customer to ensure that BP materials are suitable for the particularpurpose intended.

Insofar as materials not manufactured or supplied by BP are used inconjunction with or instead of BP materials, the customer should ensurethat he has received from the manufacturer or supplier all the technicaldata and other information relating to such materials.

BP accepts no liability whatsoever (except as otherwise expresslyprovided by law) arising out of the use of information supplied, theapplication or processing of the products described herein, the use ofother materials in lieu of BP materials in conjunction with such othermaterials.

Published by BP p.l.c. © BP p.l.c. February 2002

bp, and the Helios mark are trade marks of BP p.l.c.

Designed by LTD Design ConsultantsPrinted by Clement & Foster

20–8b/2001/1000GB

www.bpchemicals.com

For further information

BP

Logistics Technical & Safety Unit

Building A

Chertsey Road

Sunbury-on-Thames

Middlesex

TW16 7LL

UK