bulk storage of
acetic acid
contents
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
1
bulk storage of acetic acid
1. INTRODUCTION
of the bulk installation will depend upon its size and
the rate at which the acetic acid is used.
1.1 This technical booklet has been produced for
the guidance of customers who are interested in
installing bulk storage facilities for acetic acid. It
describes in general terms the requirements for a
suitable installation.
2.2 Acetic acid is available in bulk from BP in four
grades as follows: Chemically Pure Acetic Acid,
99.5% Technical, 80% Pure, and 80% Technical.
2.3 When small quantities of aqueous acetic acid
are required, it is usual to buy the appropriate dilute
grade, which is more convenient for handling.
However, where large quantities are used,
consideration should be given to the purchase of full
strength acid in bulk which can be diluted to the
required strength following receipt. The initial capital
outlay is higher, because of the additional
requirement to provide mixing equipment, but this is
offset by the saving resulting from the lower
purchase cost of the acid.
1.2 Our experience has shown that the design and
construction of each bulk storage installation
requires individual consideration, because of the
nature of the site, the users specific requirements
and the impact on any existing facilities in the
vicinity. BP offers a Technical Advisory Service, free
of charge, to customers who wish to make use of it.
We consider that our Technical Advisory Service is
most useful to a customer when discussions are
held at the earliest possible stage and certainly
before the design of the unit has been finalised. Our
local Sales Representative will be pleased to make
the necessary arrangements.
2.4 Bulk deliveries of BP’s acetic acid are normally
made by road tankers. Customers should carefully
consider the optimum storage capacity for the
installation, bearing in mind delivery load sizes as
well as current and estimated future usage.
Adequate capacity should be provided to allow a
delivery to be taken well before the previous supply
is exhausted and also to hold sufficient stock to
meet contingencies.
The storage and handling of corrosive and
flammable liquids is subject to legislative controls in
many countries. Customers are recommended to
obtain and make themselves familiar with any
relevant regulations and keep abreast of new
regulations, as and when these apply. Information
contained in this booklet is not intended to replace
any legal requirements which may be applicable to
the storage and handling of acetic acid in particular
circumstances. It is recommended however, that the
guidance outlined in this technical booklet is
followed, provided that it does not conflict with any
specific legal obligations.
1.3
3. TECHNICAL ASPECTS OF BULK
STORAGE
3.1 Acetic acid is a corrosive and flammable and
thus certain precautions are necessary if it is to be
stored and handled safely. This can be achieved by
ensuring that the storage and handling facilities are
correctly designed and constructed and that safe
operating procedures are followed.
1.4 A Material Safety Data Sheet has been issued
describing the health, safety and environmental
properties of acetic acid, identifying the potential
hazards and giving advice on handling precautions
and emergency procedures. This must be consulted
and fully understood before handling, storage or use.
Key safety and environmental data are listed in
Appendix 1.
3.2 Information on the design, construction and
location of storage installations for acetic acid
contained in this booklet is applicable only if the
temperature of the liquid remains below 30°C. At
higher temperatures, different materials of
construction may be required.
3.3 The following aspects need to be considered for
the safe and efficient receipt and storage of acetic
acid:
2. COMMERCIAL ASPECTS OF BULK
STORAGE
2.1 Although acetic acid can be supplied in
packages, for example nominal 210 litre drums, it is
often more convenient for the customer to receive
bulk supplies. Bulk storage is more compact than
storage in drums and therefore releases space and
handling equipment for other duties. Stock control is
also made easier and deliveries can be received less
frequently. There may be cost savings from reduced
handling. The time taken to recover the capital cost
2
•
Location of storage tanks
•
Tanker discharge
•
Design and construction of tanks
•
Level measurement
•
Pipework
•
Valves
return to contents
•
Pumps
•
Heating facilities
•
Pre-commissioning
•
Acid dilution
•
Labelling and safety precautions
•
Product training
•
Operating procedures
small spillages and to minimise the surface area of
any spillage.
3.4 These aspects are considered in detail in the
following sections.
4.8 The floor of the bund should be sloped to
prevent minor spillages remaining below any tank.
Provision should be made for the removal or
drainage of surface water from the area within the
bund. Surface water should preferably be pumped
out of bunds. If bund drains are used they should
be provided with valves outside the bund walls,
with procedures in force to ensure these valves
remain closed, and preferably locked, except when
drainings are being removed.
4. LOCATION OF STORAGE TANKS
5. TANKER DISCHARGE
4.1 The arrangement and any grouping of tanks
requires careful consideration. It is important to
consider access not only for normal operations but
also for emergency evacuation.
5.1 The provision of vehicle access needs to be
taken into account when selecting the site for the
storage installation. The following aspects need to
be considered:
4.2 The design of the tank farm should take
account of the likely consequences of any
accidental spillage or fire. Products which react
chemically with acetic acid should be kept in totally
segregated storage.
a)
a clear, safe access for the vehicle with
sufficient room to manoeuvre to and from the
discharge point (this must allow the vehicle to
be driven forward from the unloading point in
an emergency rather than being reversed),
4.3 Storage at ground level and in the open air is
preferable because in the unlikely event that a leak
occurs, it is more likely to be detected.
Examination, modifications and repairs are also
easier and corrosion can be more readily identified
and controlled. An exception to an outside
installation is where a small tank for glacial acetic
acid can be conveniently installed in a building
which is already heated thus removing the need for
heating and insulating the tank.
b)
the width, corners, type of surface and loadbearing capacities of the approach road,
c)
headroom under any overhead gantries,
d)
any bridge or other restrictions.
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,
5.2 Typical weights of fully laden vehicles with
dimensions and turning circle are shown in
Appendix 2.
5.3 A trial run with an empty tanker may be
appropriate if the access is doubtful.
The unloading point should be located facing the
tanker’s outlet connection to avoid the need to run
flexible hoses under or to the rear of the tanker
when discharging. Ideally, only one short length of
flexible hose should be used for the discharge
operation.
4.5 Storage tanks should be discharged by pump.
Horizontal tanks should be positioned just high
enough above ground level to provide clearance for
convenient operation and maintenance of valves.
Vehicles must not stand on a road or path used
by the public while being discharged and must be at
least 6 metres from a right of way. It is preferable if
the immediate area surrounding the discharge point
is closed to all except those directly concerned with
the operation while tanker discharge is being carried
out.
5.4
4.6 All tanks should be surrounded by a bund wall.
The required capacity of the bund may be subject to
local regulations. It should be equivalent to at least
110% of the capacity of the largest tank within the
bund. The walls and floor of the bund should be
impervious to liquid and designed to withstand a full
hydrostatic head. Bund walls should not be higher
than 1.5 metres in order to ensure adequate natural
ventilation of the bunded areas, ready access for
fire fighting and a good means of escape.
5.5 It is good practice to provide an earthing point
near the discharge point for connection to the
earthing point on the road tanker.
5.6 The rate at which the discharge takes place is
normally about 600 litres per minute whether by the
vehicle’s pump or compressor. This depends to
4.7 Intermediate lower bund walls are
recommended to divide tanks into groups to contain
3
return to contents
some degree on the configuration of the pipework to
the storage tank. When the customer’s own pump is
to be used, a similar rate should be planned.
7. LEVEL MEASUREMENT
7.1 Every tank should be provided with a suitable
means of determining the volume of the contents. A
contents indicator is preferred to manual dipping.
5.7 Road tankers are fully insulated to prevent acetic
acid freezing in cold weather.
The following types of contents indicator may be
used:
During the road tanker discharge operation acid
vapour will normally be displaced from the storage
tank vent. If the presence of acid vapour in the
discharge area is unacceptable, the installation of a
system to return the vapour to the road tanker can
be considered. Further details can be obtained from
BP’s Technical Advisory Service.
5.8
a)
Gauge glasses of the reflex type may be used with
80% acid.
They should be suitably protected on all sides
against shock damage and fitted with top and
bottom isolating cocks. They are not suitable for
glacial acid because of the difficulty of preventing
freezing in the gauge glass.
6. DESIGN AND CONSTRUCTION OF
TANKS
6.1 The storage tank must be of adequate strength
and capacity for the proposed duty.
b)
The choice of construction material for storage tanks
depends upon the grade of acid, and also on cost.
c)
Tanks constructed from the following materials
are suitable for storing 80% acetic acid.
6.2
Stainless steel grades 304, 316 and 321
b)
High density polyethylene (HDPE)
c)
Polypropylene (PP)
d)
Glass reinforced plastic (GRP) with either a
HDPE or PP lining
e)
Hydrostatic gauge
Hydrostatic gauges provide a level measurement
system requiring no external power source or
adjustment. They are simple but robust in
construction and require little maintenance. All metal
parts of these instruments should be fabricated in
stainless steel of a suitable grade.
The tank and its supports should be designed and
constructed in accordance with an appropriate
recognised standard of good engineering practice.
a)
Gauge glass
Pneumacator
This is a simple type of level indicator which is
relatively cheap but effective. Care should be taken
that all parts of the system are compatible with
acetic acid. All metal parts of these instruments
should be fabricated in stainless steel of a suitable
grade.
d)
Ultrasonic and radar level indicators
For higher accuracy in level measurement, ultrasonic
and radar level indicators are available for use with
acetic acid. Care should be taken to ensure that they
are intrinsically safe to BASEEFA (British Approvals
Service for Electrical Equipment in Flammable
Atmospheres) standard SFA 3012 for Zone ‘O’ with
certified ‘Ex’ head units and probes, or to an
equivalent standard.
Rubber lined carbon steel.
Increase in temperature can affect the mechanical
properties of some plastics and care should be taken
to avoid overheating the tank contents.
6.3 Stainless steel of ASTM 316 or 321 grade or
equivalent is suitable for the storage of all grades of
acetic acid.
Where manual dipping is necessary the
following precautions should be applied:
7.2
6.4 Aluminium of minimum 99.5% purity is suitable
for the storage of glacial acetic acid, but any dilution
of the acid should not be allowed as this will
accelerate corrosion of the tank. The temperature
control of the acid must be more precise when
aluminium is used rather than stainless steel, since
above 30°C the corrosion rate increases sharply, with
the formation of aluminium acetate.
6.5 The materials of construction described above
are only suitable for acetic acid as delivered. Where
any process material is recycled to the storage tank,
trace quantities of impurities may cause or
accelerate corrosion. Corrosion tests should be
carried out using the recycle material.
4
a)
the tank should be fitted with a dip tube
extending down close to the bottom of the tank,
with a wear pad welded to the tank bottom
beneath the dip tube.
b)
the top of the dip tube should have a vapour
tight cap which should always be in position
except when gauging is actually taking place.
c)
dip roads should be substantially smaller in
diameter than the dip tube to reduce any
inaccuracy in measurement. Wooden or
stainless steel dip rods can be used.
d)
dipping should never take place through open
manholes.
return to contents
It is recommended that each tank should be
fitted with a high level alarm, the measuring element
of which should be independent from level indicator.
An alarm operated from a float switch is suitable for
this purpose.
far removed as possible from the inlet line. To
prevent possible damage to the tank, the vent line
should not be smaller in diameter than either the
inlet or the discharge lines.
7.3
It is good practice to connect the vent line to a
scrubbing system. However, if no such system is
available, it is recommended that the tank vent is
extended down into the tank bund to within 200mm
of the floor, to prevent injury to personnel from
windborne droplets of acetic acid at the end of the
discharge. Free circulation of air around this vent is
essential to disperse vapours, particularly while that
tank is being filled. A vacuum break should be
provided on this vent line. This may be in the form
of a tun dish, or be a small hole (6mm) drilled in the
vent line above the level of the bund wall.
8. PIPEWORK
8.1 The general layout of pipelines directly
connected to the tank is shown in Appendices 3, 4
and 5. These should normally be of the same
material as the tank, except for plastic tanks, which
should have the inlet pipeline fabricated from a
suitable grade of stainless steel.
8.2 The tanker hose connecting point (inlet
connection) should be provided with a suitable fitting
to connect to the delivery hose. Suitable fittings are
described in Appendix 6. The inlet connection should
be positioned as near as possible to where the
vehicle will stand during discharge, and should be
protected from accidental damage. The inlet
connection should be located at a convenient height,
i.e., not more than 1 metre above ground level,
facing outwards, for hose coupling. The inlet line
should be fitted with an isolation valve as close as
possible to the inlet connection. When a number of
different products are stored, each inlet connection
should be clearly marked with the name of the
product to which it relates. An inlet line of 80mm
nominal bore is a suitable size for transferring acetic
acid from the road tanker to the tank. The line
should enter the top of the tank. The inlet should be
sloped towards the tank as shown in Appendix 3. A
drain cock should be fitted at the lowest point in the
inlet line so that the line can be drained at the
completion of tanker discharge. Space for a small
receptacle (20 litres capacity) should be left under
this drain cock.
8.6 In order to reduce vapour emissions to the
atmosphere it is possible that legislation will in
future require that bulk deliveries of acetic acid are
made using a vapour return system or a tank with a
vent scrubber. A typical vapour return system is
shown in outline in Appendices 3 and 4. Vapours
displaced from the storage tank during delivery
would be transferred to the vapour space of the
delivering tanker.
8.7 Wherever possible, continuously welded
pipework should be used. However, where pipework
may have to be disconnected for maintenance or
inspection, flanged joints should be fitted. Flanges
conforming to the American National Standards
Institute (ANSI) 150lb and PTFE envelope gaskets
are recommended. Other suitable gasket materials
are shown in Appendix 7. Graphitised jointing paste
should not be used with stainless steel.
8.8 A vapour tight manhole should be provided on
all tanks to allow for internal inspection and cleaning.
8.9 An earthing point should be fitted on tanks
containing pure acetic acid, and this should be
connected to a good earth. The resistance to earth
at any point of the installation should be less than 10
ohms. This also applies to the tanker earthing point
which preferably should be connected to the same
earth, or if independent should have minimal
resistance between this and the tank-pipework
system. It is good practice to fit an earthing point on
tanks containing 80% acetic acid.
A tank discharge line should be provided which
should be a minimum of 50mm nominal bore. The
discharge line is usually taken through the bottom or
the side of the tank to an isolating valve.
8.3
This isolating valve should be located as close as
possible to the tank. In all cases, discharge should
be by pump. The pump and controls should be sited
outside the bund.
8.4 If the tank discharge line is not located at the
lowest point of the tank, a facility should be provided
for draining the tank. A 25mm nominal bore branch
fitted at the lowest point of the tank is suggested.
The branch should be fitted with a suitable isolating
valve and blanked off when not in use.
8.10 The pipework system should be designed such
that liquid cannot be trapped between closed valves
without some form of pressure relieving device. This
applies especially to heated pipework (see section
11).
A vent line needs to be provided, leading from
the vapour space at the top of the tank, for the
dispersion of vapour. This vent line should be
connected to the highest point of the tank and be as
8.11 Joints in pipework should not be located over
doorways, windows or close to possible sources of
ignition.
8.5
Pipework should be routed to minimise the
possibility of accidental damage.
8.12
5
return to contents
9. VALVES
Temperature control
Stainless steel ball or gate valves with PTFE
seats are recommended for use with acetic acid and
are suitable for all applications.
11.3 If heating is provided, thermostatic temperature
control is strongly recommended to ensure that the
temperature of the acetic acid does not exceed
30°C. At higher temperatures the rate of corrosion
of stainless steel by acetic acid increases and
flammable mixtures of air and acetic acid are
possible. The fitting of low and high temperature
alarms is recommended.
9.1
9.2 Plug or diaphragm valves can also be used with
acetic acid. However, diaphragm valves should not
be used on the bottom outlets of tanks.
9.3 PVC or polypropylene ball valves can be used
for 80% acetic acid.
11.4 Thermostatic control also ensures economy in
the usage of the heating medium and minimises
vent loses. The temperature sensing element for the
tank should be installed in a 40 mm nominal bore
pocket at the side of the tank and which extends
towards the bottom of the tank at a point remote
from the heating element. The thermometer pocket
should be of stainless steel, filled with oil. If heating
is by hot water or steam and instrument air is
available, a simple pneumatic temperature indicating
controller will be adequate. If instrument air is not
available a direct-acting controller must be used, and
a direct reading temperature indicator should be
installed.
10. PUMPS
10.1 Pumps should be located outside tank bunds,
on an impervious base, in an open space, and not in
walled or confined spaces.
10.2 Pumps for 99.5% acetic acid should be
fabricated from a suitable grade of stainless steel,
i.e. ASTM 316. Polypropylene may be used for 80%
acetic acid.
Self-priming centrifugal pumps should be used
wherever possible. Mechanical seals with PTFE
wedges (Crane Type 109 or equivalent) are
recommended for this duty but these seals must
not be run dry. If packed glands are used, braided
PTFE should be used. If metering or other
reciprocating pumps are used, PTFE packing is
preferred. Glandless centrifugal pumps with
magnetic coupling may also be used.
10.3
With electric heating, a simple on/off
thermostatic control switch will be adequate.
11.5
Heating of the storage tank
For glacial grades, the storage installation
should be designed to maintain the tank contents at
a temperature of 25°C ± 5°C. If the tank is installed
inside a building, provided the ambient temperature
is not allowed to fall below 20°C, no additional
means of heating is required. Precautions will still
have to be taken to avoid freezing of the inlet and
vent pipes if these pass outside the building.
11.6
Arrangements should be made to collect any
leakage from glands. Connections at the pump
should be flanged to ANSI 150lb. Threaded joints
must not be used.
10.4
10.5 When glacial acetic acid is being handled, it is
normal practice to drain a pump after use and to
close the isolating valves until it is required again.
If the tank is installed outside, an internal
stainless steel (ASTM 316L) heating coil is
recommended. This may be heated by either hot
water or low pressure steam. Electric heating pads
can be used but these should be designed so that
overheating of the surface of the tank does not
occur.
11.7
10.6 If pumps can be remotely controlled, a stop
button should be provided both at the pump, and at
the delivery point.
10.7 Suitable materials for use as seals and hoses
are shown in Appendix 7.
11.8 In all cases where storage tanks are heated,
they must also be effectively insulated.
11. HEATING FACILITIES
Heating of pipework
Introduction
11.9 The ratio of heating surface to liquid volume is
much higher in pipework than in the storage tank.
This means that acid in a pipe is much more
susceptible to overheating, if heat is applied, or to
freezing if the insulation is faulty. In view of this,
some system of thermostatically controlled heating
on the pipework is recommended. Care must be
taken to avoid high surface temperatures, as these
might cause an increased rate of corrosion and
In most situations it is necessary to take
precautions, such as the provision of heating and/or
insulation, to prevent glacial grades of acetic acid
from freezing in tanks and pipelines. These grades
freeze at temperatures between 14°C and 16°C.
11.1
For 80% grades, the need for precautions to
be taken to prevent freezing of the acid will depend
upon the location of the tank and local ambient
temperature conditions. 80% grades of acetic acid
freeze at -7°C. Consequently, in many cases special
precautions are unnecessary.
11.2
6
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consequent contamination of the acid.
12. PRE-COMMISSIONING
11.10 Pipelines may be heated electrically or by hot
water. Electric heating tapes wrapped around the
pipe or electric heating elements running along the
underside of the pipe may be used. When hot water
is available, a 15mm nominal bore mild steel trace
line can be run directly below the acid line. The
tracing is supported by the acid line but small
spacing pads prevent direct contact. Maintenance is
simplified if the trace line is jointed adjacent to the
acid line joints. For pipelines in continuous service
automatic control must be used to avoid
overheating.
12.1 When the bulk installation is completed it is
normal practice flush the whole system through
with water to remove any debris. When this is done
it is advisable to:
a)
fit fine wire mesh strainers at the inlets of
pumps and meters to prevent them being
damaged by solids,
b)
use water with a low chloride content i.e. below
30ppm, to avoid any possibility of chloride
corrosion of the stainless steel.
Where a stainless steel tank is to be used, and
the iron content of the product is important, it is
advisable to condition the tank before use, to
remove iron. BP will be pleased to advise on
suitable conditioning procedures.
12.2
For occasional duties, such as the inlet line, steam
heating may be used. The installation should be
similar to hot water heating, with steam traps at all
low points. The line should be drained after use and
the heating properly shut off. To ensure complete
drainage the slope of the line should be increased to
1 in 50.
13. ACID DILUTION
Introduction
It is most important that the vent line is fully trace
heated and insulated to avoid blockage by
crystallised acetic acid vapour during cold weather.
13.1 Reference to price schedules will show
whether it is economic to buy glacial acid and dilute
it with water down to the required strength. There
are no major process difficulties and personnel soon
become accustomed to the method of dilution and
its control.
Heating of pumps
Steam/water-jacketed pumps can be obtained
but are not usually necessary. It is normally sufficient
protection if the pump is sited inside a warm building
or if the heating element or tracing line is continued
around the base of the pump.
11.11
Water quality
13.2 All town water contain soluble salts, although
some waters are of a better, or softer, quality than
others.
Heating of valves
Steam/water-jacketed valves are expensive
and not readily available. It is normally adequate to
continue the heating element or tracing line close to
the valve body.
11.12
13.3 The quality of the diluted acid depends upon
the quality of the water used. For this reason, it is
recommended that for high grade 80% acetic acid
demineralised water or distillate is used as diluent.
Filtered steam condensate may be used only if it
has not been in contact with mild steel equipment.
However, not all customers require such a high
grade product. In such cases, ordinary towns water
may be used as diluent. However, it should be noted
that contaminants, e.g. chloride, can cause
increased corrosion in subsequent processing.
Thermal insulation of tanks and lines
11.13 Heated tanks, pumps and pipelines should be
insulated to prevent heat losses and reduce heating
costs. In addition, if the installation is sited outdoors,
the insulation must be weatherproofed.
11.14 Preformed types of insulation are
recommended. Preformed slabs or mattresses may
be used with tanks, and preformed sections of
adequate bore for the pipelines plus heating devices.
All flanges, valve bodies and pumps should be
insulated.
Dilution equipment
13.4 The dilution is normally carried out in the bulk
storage tank. The tank should be sized, therefore, to
contain the required delivery of acetic acid, plus the
dilution water, plus any residue of diluted acid which
had not been utilised. Acid and water are intimately
mixed using either a top entry agitator or a jet mixer
nozzle and pump. Jet mixing is normally the more
convenient method. It is favoured by the basic
geometry of a storage tank and the cost can be less,
particularly as a pump is usually required for other
purposes.
11.15 For tanks and pipework in stainless steel,
chloride-free insulation must be used or corrosion
will result.
7
return to contents
where W is the amount of water to be added in
litres and M is the amount of 99.5% acid in tonnes.
13.5 Jet mixing is simply the circulation of acid from
the tank into a pump and back into the tank through
an inclined nozzle at the tank base. The jet of liquid
from the nozzle produces the stirring action in the
tank.
For different strengths the following equation may
be used:
W = M x (X - 80) x 125.24
10
The nozzle design is critical, depending on the
geometry of the tank and the pump rating. Our
Technical Advisory Service engineers will, on
request, advise on a jet mixing system for the
proposed duty.
13.6
where X is the initial concentration of acetic acid,
mass per cent, W is the amount of water to be
added in litres and M is the amount of acid in
tonnes. Thus, for X = 99% m/m
The nozzle should not be used until there is about
1.5 metres of liquid above it. Mixing time is so short
that this is not at all a serious disadvantage. The
tank should not be filled through the nozzle.
W = 1 x (99 - 80) x 125.24 litres per tonne
10
= 19 x 125.24
10
= 238.0 litres per tonne
The inlet delivery line should be heat traced and
insulated.
Demineralised water
14. LABELLING AND SAFETY
PRECAUTIONS
Where demineralised water is used for the
dilution of acid, a tank should be installed for the
storage of the treated water. The economics of
water treatment are such that it is cheaper to install
a small capacity demineralising unit feeding over a
prolonged period of time into a water storage tank
rather than a large capacity unit feeding into the acid
tank over a short period. Alternatively, the acid tank
can be filled slowly with water if not required
continuously.
13.7
14.1
The words:
ACETIC ACID – CORROSIVE TO SKIN
should be painted on all acetic acid bulk tanks.
Emergency instructions, in case of splashing, should
be shown at the main places of work. An adequate
number of eye baths or wash bottles containing
water (for use until a source of running water can be
used) should be kept in the working area. Buckets of
sodium bicarbonate may also be kept in the working
area for skin use only.
13.8 Demineralising equipment is supplied by
manufacturers specialising in this field and their
advice should be sought regarding the most suitable
unit for a specific application.
In addition, safety showers with a quick acting
valve, adequately protected against frost, or a water
bath should be installed on site. There should be an
adequate supply of water for hosing down the area
in the event of an acid spillage.
14.2
Demineralised water is corrosive to some
materials. Equipment such as the treated water
storage tank should be of corrosion resistant
material. Stainless steel, ebonite-lined carbon steel,
polyethylene or polypropylene may be used.
13.9
14.3 Buildings in which acetic acid is stored or
handled should be well ventilated.
Method of dilution
15. PRODUCT TRAINING
It is recommended that initially up to 80% of
the water required for dilution is added before the
acid delivery. After the delivery, the tank can be jet
mixed and the contents sampled. Measurement of
the relative density of the liquid and its assay will
give the quantity of acid in the tank.
13.10
All personnel associated with the handling of acetic
acid should be fully trained to enable them to
understand:
It is a simple matter to calculate the additional water
and to add the quantity required accurately. The tank
is again jet mixed and the assay checked. As the
operator becomes more skilful in the technique of
dilution, the initial charge of water may be increased
to say 90%.
Calculation of dilution
13.11 For the dilution of 99.5% by mass acetic acid
to 80% by mass:
W = 244.1 M
8
a)
the nature of the potential hazards associated
with the handling of acetic acid,
b)
the appropriate storage and handling
precautions including personal protection
measures,
c)
the appropriate action to be taken in the event
of an emergency.
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16. OPERATING PROCEDURES
closed. The drain cock adjacent to the inlet
valve should then be opened carefully, to allow
any product remaining in the inlet pipe to drain
into a receptacle. Next, the hose should be
drained through the inlet valve and drain cock
into a receptacle (5 to 10 litres of drainings may
be expected). It is the customer’s responsibility
to provide adequate facilities for disposal of
these hose drainings.
Written operating instructions should be available for
the receipt of acetic acid, and operating personnel
should be fully trained in their implementation. The
instructions should take account of the specific
hazards, and ensure the correct operation of
equipment in both normal and emergency situations.
Key points of a typical discharge operation for bulk
road tankers are:
a)
b)
h)
the customer's representative must ensure that
there is sufficient ullage available in the
receiving tank to accept the nominated delivery.
the delivery hose should be thoroughly washed
through with water.
i)
prior to discharge, all appropriate safety
equipment must be checked and suitably
positioned.
all equipment must be properly stowed before
the road tanker is given authorisation to depart
from the discharge point.
j)
finally, the quantity in the tank should be
checked against the amount expected. Dipping
the tank or removal of a sample for testing
should not take place until at least 30 seconds
after completion of discharge. This is to allow
for the relaxation of any electro-static charge
which may have been generated in the transfer.
c)
only those personnel directly concerned with
the discharge operation should be in the area,
with appropriate protective clothing being worn.
d)
a customer’s representative must identify the
discharging point to be used, and the earthing
point, and must supervise all connections to the
vehicle.
e)
f)
g)
17. FURTHER TECHNICAL LITERATURE
the road tanker should be connected to the
earthing point before the delivery hose is
connected. This earth must be maintained
throughout the operation and not be broken
until after the hose is disconnected, on
completion of product transfer.
Further technical literature on acetic acid is
available from BP as follows:
17.1
during discharge, regular checks should be
carried out to ensure that the load is being
received into the appropriate storage tank. The
customer's representative must remain in
attendance throughout the discharge operation.
a)
BP Acetic Acid Product Specification and
Physical Properties.
b)
Material Safety Data Sheet, giving health, safety
and environmental data.
Copies of Material Safety Data Sheets are normally
supplied automatically by our Sales Offices. Further
copies are available either by direct request to the
Sales Office or by asking our local sales
representative to arrange for copies from the Sales
Office.
on completion of discharge, the pump (if used)
should be stopped and the valves in the pipeline
9
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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
Freezing points
Flammable limits in air
463°C
Acetic acid chemically pure
16.6°C
Acetic acid 80% pure
-7.0°C
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.
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
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Actual values will depend upon the vehicle design and construction regulations currently in force in the country
concerned.
10
750 mm
approx.
protective
cap and
chain
65mm
intake
valve
11
Tanker earthing with
bulldog clip
Single short length
of flexible hose
2½" BSP male
inlet connection
Intake point for
road tanker delivery
50mm
drain
branch
Tank
earthing
1 m min
Sump
LI
38mm vapour return
(where fitted)
Tank contents to
be clearly
marked on tank
Slope to
tank
Products to be
clearly marked
at delivery point
Bund wall
80mm inlet line
2m long common
copper earthing rod
25mm
drain
valve
1 Max bund height 1.5m
2 Tank heating will be required for glacial grades of acetic acid
Slope
Tank supports
steel or concrete
Slope
TI
Bund wall
50mm ball
valve
1m
min
Vent
scrubber
(alternate
design)
Fixed access
ladder
Impervious base
80mm minimum
vent pipe
Tank insulation
(glacial grades)
LAH
600mm manhole
with bolted cover
Pressure/vacuum
valve
Town's water supply
Shower located adjacent
to storage installation
incorporating quick acting
valve and eye-bath
50 mm
delivery line
To pump
Pipes to be
sealed in
bund wall
Water
Water hose for
washing down
APPENDIX 3
DIAGRAM OF TYPICAL ABOVE GROUND STORAGE INSTALLATION
return to contents
750mm
approx.
protective
cap and
chain
12
\`
65mm
intake
valve
Tanker earthing with
bulldog clip
Single short lengths
of flexible hose
2½ inch BSP
male
Intake point for
road tanker delivery
25mm
drain
valve
38mm vapour
return (where
fitted)
Bund wall
Product to be
clearly marked at
delivery point
1 Max bund height 1.5m
2 Min bund wall to tank 1m
3 Tank heating will be required for glacial grades of acetic acid
Sump
Slope
80mm inlet line
Non-return
valve
Handrails
50mm
drain
Slope
Wear
plate
Mixing nozzle
Tank contents to
be clearly marked
on tank
Tank
earthing
LI
Common earth system
Manhole
Tank insulation
(glacial grades)
LAH
150mm min
600mm manhole fitted with
hinged emergency relief
hatch
pressure/
vacuum
valve
Impervious base
TI
Bund wall
To pump
Pipes to be
sealed in
bund wall
Water
Vent
scrubber
Sample point
Fixed access
stairs
Pump recycle
50mm dip pipe
with screwed cap
local to stairs
APPENDIX 4
DIAGRAM OF TYPICAL ABOVE GROUND FIXED ROOF STORAGE
INSTALLATION
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13
Reinforced
concrete
Sealed to keep out
water
2m long common
copper earthing rod
Tanker earthing
lead with bulldog
clip
Note: Tank recirculation system not shown
Tank earthing
Inlet connection for
road tanker delivery
Single short lengths
of flexible hose
80mm fill and dip pipe
fitted with lockable cap
Wear plate
Product and vapour
return, where fitted, to be
clearly marked at delivery
point
38mm vapour
return (where
fitted)
To pump
Tank supports
steel or concrete
Pit back filled with dry
sand
Tank and pipes below ground to be
protected against external corrosion
50mm suction line
LI
80mm minimum vent pipe to safe
location (to be fitted with a
pressure relief system if a vapour
return system is used)
Flame arrestor
APPENDIX 5
DIAGRAM OF TYPICAL UNDER GROUND STORAGE INSTALLATION
return to contents
APPENDIX 6
SUITABLE FITTINGS FOR TANK INLET CONNECTIONS
UK:
2.5 inch BSP parallel threaded male connection
France:
symmetric coupling NF-E 29.572, 80 mm nominal
diameter (type ‘Guillemin’ or equivalent)
Germany:
quick coupling DIN 28450, 3 inch male connection
APPENDIX 7
Seals
SUITABLE MATERIALS FOR SEALS, GASKETS AND HOSES
Ethylene propylene rubber (EPDM)
‘Kalrez’
Butyl rubber
PTFE encapsulated
Gaskets
PTFE envelope
EPDM
return to contents
Butyl rubber
Hoses
Polyethylene
Polypropylene
Stainless steel (316)
EPDM
Butyl rubber
PTFE
14
For further information
BP
Logistics Technical & Safety Unit
Building A
Chertsey Road
Sunbury-on-Thames
Middlesex
TW16 7LL
UK
www.bpchemicals.com
EXCLUSION OF LIABILITY
Information contained in this publication is accurate to the best of the
knowledge of BP p.l.c.
Any information or advice obtained from BP otherwise than by means of
this publication and whether relating to BP materials or other materials, is
also given in good faith. However, it remains at all times, the responsibility
of the customer to ensure that BP materials are suitable for the particular
purpose intended.
Insofar as materials not manufactured or supplied by BP are used in
conjunction with or instead of BP materials, the customer should ensure
that he has received from the manufacturer or supplier all the technical
data and other information relating to such materials.
BP accepts no liability whatsoever (except as otherwise expressly
provided by law) arising out of the use of information supplied, the
application or processing of the products described herein, the use of
other materials in lieu of BP materials in conjunction with such other
materials.
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 Consultants
Printed by Clement & Foster
20–8b/2001/1000GB