Chapter - 02-204
Chapter - 02-204
Chapter - 02-204
Chapter
2
-
☯ General Consideration
☀ NFPA & OISD Standards
☀ Design of Storage Layout, Dyking requirements. Incompatibility Criteria
☯ Types and Safe Layout of Storages
☀ Tank layout of LPG, Chlorine, Ammonia, EO, Oleum
☀ Isolated storages
☀ Mounded storages
☀ Cryogenic storages
18
CHAPTER – 2
BULK STORAGES
CONTAINMENTS
• Properties – Physical, chemical
• Hazards – health, flammability, reactivity
• Compatibility with the container and environment
CONTAINERS
• Compatibility with the containment and environment
• Material of construction
• Shape
• Design – Codes, Standards
MOUNTINGS
• Nozzles orientation
• Drive
• Instruments – temperature, pressure, level, flow etc
SURROUNDINGS
• Environment – temperature, Humidity
• Protective means – fire protection, explosion barriers
• Spare container or blow – down tanks
• Flare
• Fencing
• Lighting – flameproof / non-flameproof
• Dyke
• Drainage
19
ADMINISTRATIVE FACTORS
• Fencing
• Restricted and authorized entry
• Training
• Appraisal
• Inspection & testing
NFPA is an internationally recognised body and their standards, codes and manuals
are followed by not only by American Government and industries but also by other
countries in the world.
The NFPA is the clearinghouse for information on the subject of Fire prevention,
Protection & Fire fighting. It is non-profit technical and educational organization with
a membership network of around 68,000 companies and individuals
The technical standards issued as a result of NFPA committee work are widely
accepted by federal, state and municipal governments as the basis of legislation
and used as a guideline of good practices.
More than 50 serve as OSHA regulations. More than 300 codes and standards are
currently issued by NFPA which are constantly reviewed and updated
The code indicates
Relative risk to health
Flammability
Instability
Possible specific hazards (symbol)
The first three aspects are assigned a value in range 0-4, the higher the value the
higher the risk.
Representative subject include
Air conditioning and Ventilation system
Brigades
Flammable Chemicals data
Industrial Fire Loss Prevention
Life safety code handbook
National electric code handbook
Portable fire extinguishers
Powered industrial trucks
Prevention of dust explosion in industries
20
Protection of records
Safeguarding building construction operations
Sprinkler system
Organization and training private fire brigades
Storage and handling of liquefied petroleum gases
Truck fire protection
Other publications of interest to safety professionals concern hazardous materials,
fire safety to health care facilities, and public fire safety.
In addition the fire protection handbook is an authoritative encyclopaedia of fire loss
control
21
There are different types of design of storage sheds. Some are open from all sides,
some are partially open and some are closed
Considerations are
➥ FLOORS
Depending upon the load and type of operations, the conditions of the floor
such as
• Cleanliness
• Absorptive qualities
• Marking
• Colour
• Non-sparking of static disseminating properties
• Durability will give great effect on material handling
Floor used for stacking should be of sound construction, well maintained,
levelled and facilitating drainage
Floor slope on one side or at centre for not allowing any liquid to accumulate
Shed should be adequately ventilated as per vapour requirement
Fire detectors at proper locations, surrounding open space for easy
movement
Sufficient head room for fire fighting, proper stacking, sufficient lighting,
proper ventilation etc
Sufficient room height and proper roof design according to ventilators
Alarm system in case of fire and leakages
Proper locking system for explosives, poisonous chemicals, radioactive etc.
Floor slope should be connected with the drain and collection pit
Sufficient doors and emergency exits to be provided
Sufficient lamps and tubes for sufficient illumination
Suitable space for truck parking during loading / unloading activities
Gangways must be at least 60 cm wide
Different sections with necessary partition for incompatible chemicals and for
liquid, solid and gases
As far as possible fire proof materials of construction and electrical fittings to
be used
FLAMMABLE LIQUIDS
Detached location should be preferred
Best location – open under non combustible weather canopies
Where detached location is not possible, fire resistant walls (a room cut off
from rest space), fire and pressure resisting construction is advisable
22
FLAMMABLE GASES
Gases are generally contained in cylinders in compressed, liquefied or
dissolved state
Cylinders are protected from sunlight, damage or deterioration and heat (so
proper roofing and room if required to be provided)
Safe cradle on platform with guard rails should be provided for lifting
Storage rooms should be dry, cool and adequately ventilated
Adequate illumination and lighting should be available
Non compatible cylinders should be stored separately using proper partition
Various gas detectors and fire detectors with alarming system is of first
importance
Auto sprinkler and other auto fire extinguishing system is preferable
Adequate fire extinguisher at particular places / distances
PURPOSE
Dyke walls are required to restrict the spread of the leaking material
To safely contain material (leaking) within its periphery and restrict the
surface area of leaking material
To reduce its evaporation (of leaked material)
For ease of fire fighting or other emergency control activity
23
24
ISOLATED STORAGE
“isolated storage’’ means storage where no other manufacturing process other than
storage, loading / unloading / pipe line transfer by pumping of hazardous chemical
is carried out and that storage involves at least the quantity of that chemical set out
in Schedule 2, but does not include storage associated with an installation specified
in Schedule 4 on the same site;
SCHEDULE - 2
[See rule 2(c) (ii), 4(l)(b), 4(2) (1) and 6(1) (b)]
MOUNDED STORAGE
A storage vessel which may sited above ground or partly buried and which is
completely covered by a mound of earth or similar inert material.
Mounded vessels should be covered by a suitable material which is inert, non-
corrosive, free from particles of abrasive materials likely to damage the vessel
coating and carefully consolidated to give a minimum cover of 500 mm.
The mound should protect the vessel from the effects of thermal radiation and
should be sufficiently robust to remain in place in the event of jet flame
impingement.
25
Mounded storage
Semi-Mounded
Mounded storage
26
CRYOGENIC STORAGE
A storage below —40 °C is referred as cryogenic sto rage. Extreme stresses should
be considered for design of such vessel. It is so low temperature and hence likely to
cause vacuum inside the vessel and likely to cause implosion by the external
environmental pressure. Vacuum breakers or relief systems should be provided on
such vessel.
After chlorine and Ammonia, the third chemical of major industrial use is LPG. It is
stored as liquid and transmitted by high pressure pipeline for industrial and
domestic uses. Fire and explosion is the main hazard associated with it.
PROPERTIES
Expansion ratio: liquid LPG when exposed to normal atmospheric condition rapidly
evaporates expanding 270 times its own volume of vapours
TLV: 1000 ppm
LPG is colourless & odourless; therefore, methyl mercaptant is added to facilitate
defect presence of LPG by its foul smell.
LPG is heavier than air & hence tends to settle at ground level
LPG tank is also called as Bullet
LPG tanks can be sited above or underground (mounded)
• Bullet — for pressure in the range of 7 to 10 kg/cm2
• Sphere For high pressure storage above 15 kg/cm2
• Fully Mounded — Inerting from all the sides of the tank
• Semi-mounded — Inerting is partly
27
28
Being a compressed gas, all installations and tank vehicles used for storage and
transport of liquid and gaseous chlorine have to be approved and licensed under
the Static and Mobile Pressure Vessel (unfired) Rule, 1981
For bulk storage it is also called as Bullets and for Tonne storage for transportation
it is called tonner
29
BULK STORAGE
Appropriate minimum safety distances as stipulated in the above mentioned
rules have to be maintained
The tank has to be installed entirely above the ground
The bulk storage tanks must be installed near waste-air system
At least two safety valves should be connected to the waste-air system
Pressure indicator with alarm should be available in the control room
If continuous supply is required, it is essential at least two tanks
Distance between adjacent storage tanks shall be adequate
All tanks shall be installed in a bund wall with sufficient floor slope
Area should be planned to provide facilities for good housekeeping
For vessel operating at low temperature lagging is required
Chlorine leak detector must be provided at various points in storage area
As an emergency measure, a perforated pipe, connected to blower suction
around storage tanks should be provided
It must be capable of handling 12 bar pressure and temp -35°C to +45°C
The storage tank capacity must be significantly greater that the capacity of
full load of liquid chlorine
The vessel supports should be designed in accordance with the design code
to permit thermal expansion or contraction over the design temperature
range
Branch dimensions should be limited to minimum required, particularly for
liquid line
Manhole access should be provided on the top of the tank
Following connections are permitted to the tank
• Liquid inlet
• Liquid outlet
• Vent lines & compressed gas lines
• Relief system
• Instrumentation and pressure gauges (fail safe instrumentation
recommended)
• The number of connections should be minimum & arrangements
should be made simple
• A back up isolation valves should be provided
30
PROPERTIES
Colourless gas, pungent smell, irritant
Melting point: -77.7°C, boiling point: -33.35°C
LEL: 16%, UEL: 25%, TLV: 25 ppm, STEL:35 ppm
Density: 0.771 g/l at 0°C
Fire hazard low, Explosion hazard moderate when exposed to flame, when heated
emits toxic fumes
To fight fire stop flow of gas
STORAGE CONDITIONS
Three methods of storages are currently used; the choice depends upon quality to
be stored
Storage at ambient temperature and equivalent pressure n cylindrical vessel.
This method is used when relatively small quantities are involved as practical
manufacture and transport consideration limit the size of vessel
31
INDOOR
Storage should be cool, dry, well ventilated and protected from external heat
sources
The building protected with automatic sprinklers, vapour tight electrical
equipment, good natural ventilation, good floor drainage and adequate
exposition venting
OUTDOOR
Each storage area should be protected at least by one standard fire hydrant
Area should be barricaded off from unauthorised entry
Vents of storage tanks must lead to a safe location (e.g. scrubber etc.)
Tanks must be located at least 15 meter away from buildings
Should be away from flammable material storages
Dyke of adequate capacity with slopping floor
Fire proof electrical fittings and equipments shall be provided
Sound foundation
Safe guarding against direct sunlight
32
PROPERTIES
Colourless gas
Melting point: -113°C, Boiling point: 10.7°C, Flash point: -17.8°C
LEL: 3%, UEL: 100%
Density: 0.8711 at 20°C
TLV: 1 ppm
LD50(rat): 330 mg/kg, LC50(rat): 1462 ppm for 4 hours
It is toxic, flammable and explosive
Fire and explosion hazard when exposed to heat or flame, vaporise rapidly at
ambient temperature, can cause cold burns and it is soluble in water
33
34
PROPERTIES
35
36