LNG handling |||
LPG handling||| Other Gas products|||
Fire & Safety|||
Emergency response |||
Fire involving LNG & LPG cargo - various fire fighting agents & safety aspects
Natural gas contains numerous component gases but by far the greater
percentage is methane (CH4), which represents between 60 and 95 per cent
of the total volume. This fact is important when considering the safety
aspects for fire-fighters tackling an LNG fire.
During the initial period of vaporisation of the gas, ignition may be
accompanied by a flash of varying proportions.However, because the velocity
of propagation of a flame is lower in methane than in other hydro-carbon
gases, it is unlikely that future ignition will have flash effect.
The fire-fighting plan should be well thought out in advance and a
concentrated effort made rather than ‘hit and run’ tactics, as these will only
consume the vessel’s extinguishing facilities without extinguishing the fire.
Before attempting to tackle a large fire, you should seriously consider
allowing the fire to burn itself out.
Should an attempt to extinguish the fire be made, extensive use of ‘dry
powder’ should be employed from as many dispensers as can be brought to
bear. Fire-fighters should be well protected against heat radiation and possible
flash burns, and approach the fire from an upwind direction. Power
dispensers should sweep the entire area of the fire, but direct pressure of
powder jets on to the surface of the liquid should be avoided.
Should dry powder guns be used, fire-fighters should be well practised
in their use and be prepared for some kick-back effect.They should also be
made aware that there is no cooling effect from the use of dry powder, and
that re-ignition after a fire has been extinguished is a distinct possibility.
In the initial stages it is always preferable to isolate the fire by shutting
off the source of fuel.This may not, however, always be possible.
A final warning when tackling an LNG fire is that water should not be
used directly, as this will accelerate vaporisation of the liquid.This is not to
say that surrounding bulkheads and decks cannot be cooled down with
water sprays, provided that water running off is not allowed to mix with
Dry powder :
Dry powder is provided both in large fixed installations and portable extinguishers.
Any part of the deck can be reached by at least two hoses from the fixed installations.
Water extinguishing :
Water is not a suitable medium for fighting an LNG fire directly as it will cause a massive expansion
of the fire, through an increase in the rate of vaporisation of the liquid to gaseous state.
Water is however essential as a cooling medium for the area surrounding an LNG fire and to
protect personnel who may need to approach the site.
Water is also essential for protecting steel work from the effects of extreme cold in the event of a
A CO2 extinguisher system is available for cargo compressor rooms, electric motor rooms, inert gas
dryer room and on some ships cargo control room.
Ships plans should be consulted for what is applicable to the concerned vessel.
How to tackle LNG fire ?
The rapid vaporisation of any exposed LNG prevents any ignition of the liquid itself and an LNG fire
is thus a cold vapour fire.
Ignition of a flammable mixture of natural gas vapour requires a spark of similar ignition energy as
would ignite other hydrocarbon vapours. The auto-ignition temperature of methane in air (650°C)
is higher than other hydrocarbons.
Electrostatic ignition of LNG is not a hazard during normal operations. This is because the
permanent, positive pressure in LNG tanks maintained by gas boil-off prevents air entering these
spaces to form flammable mixtures in tanks or lines.
The velocity of propagation of a flame is lower in methane than nearly all other hydrocarbons.
Unless ignition occurs during the initial rapid vaporisation period, it is most unlikely that any flash
will accompany an ignition. The term ‘lazy flame’ has been aptly used to describe the spreading
characteristics of an LNG fire.
Burning of LNG vapours produces a similar flame size and heat radiation to other hydrocarbon
fires, but little smoke is produced.
From a fire fighting viewpoint, LNG/cold vapour fires have the characteristics of both liquid and
gaseous hydrocarbon fires.
The procedure for fighting these fires is:
The exact procedure will depend upon the nature of the incident.
Before attempting to fight large fires, thought should be given to the desirability of letting a fire
burn itself out. Such strategy runs the risk of the fire spreading and greater damage being caused,
but other factors to take into account are:
- Isolate the source of leak, stop loading/discharging, and shut all manifold valves.
- Sound the alarm.
- Provide protection for adjacent equipment and for fire-fighters.
- Attack fire with a maximum rate of application of dry powder. Do not agitate the surface of
any pool of LNG.
- Remain on guard against possible re-ignition.
- The possibility that the dry powder capacity may be exhausted before the fire is
extinguished, or, if the fire is extinguished, reserves have been run so low that any reignition
could not be contained.
- The risk of damage to life and property if an un-ignited flammable mixture drifted in light
wind conditions to an area of high ignition risk.
The following fire fighting agents may be used:
Water spray systems
It is a requirement that a series of water spray nozzles are located at each tank liquid and vapour
dome, at the midships manifold, on the compressor house, on the forward bulkhead of the
accommodation block and around the midships cargo control room if applicable. The water for the
operation of these nozzles is fed from a pump and line system independent from, but crossconnected
with, the ship's fire main. In addition to the above system, the sides of the
accommodation block may be protected by spray nozzles supplied with water from the fire main
via isolating valves.
Water should NOT be used to extinguish LNG fires as it increases the vaporisation rate and hence
the burning rate. However a water spray or fog should be used to protect personnel and to cool
areas adjacent to the fire. The qualities that make water unsuitable for fighting LNG fires make it
an ideal medium for spraying LNG spillages to increase evaporation rate and prevent re-ignition,
provided that the LNG is not actually burning.
Care is necessary to avoid water running off adjacent structures and aggravating burning LNG, or
splashing into spill trays which may contain LNG, thus causing it to overflow onto unprotected
steelwork. Spill trays and areas under manifolds are in any case floodable with water to protect
hull steelwork from damage due to exposure to the intense cold of LNG.
Water jets can be used to deflect burning jets from impinging on other tanks. Care should be taken
to avoid extinguishing the fire with the consequent danger of re-ignition of large volumes of
Dry chemical powder
Dry chemical fixed installations are provided on Gas Carriers. Manufacturer’s instructions should be
referred to for details of operation and maintenance procedures. Whenever a dry powder hose has
been in use, it should be blown clear with nitrogen to prevent any possibility of blockage.
The extinguishing power of dry chemical powders depends on the chemical reaction of the small
particles when exposed to flame. They are flame inhibiting agents and have been widely proven in
LNG fire tests.
The maximum possible rate of application of dry powder is desirable. As many high velocity jets as
possible should be brought to bear at once, preferably in a down wind direction. Jets should be
aimed with the objective of reducing boil-off rate by sweeping over the whole fire area and on no
account must the surface of an LNG pool be agitated. Possible re-ignition must be guarded against.
Correct use of dry chemical powder equipment is essential if reserves are not to be wasted and the
fire is to be successfully extinguished. Extinction with dry powder is obtained by maximising the
rate of application and minimising any agitation of pools of LNG. This may be achieved by coordinating
a simultaneous attack with all available applicators. A first-aid shot with only one hose
or monitor may be warranted with small fires, but continuous individual efforts can never be as
successful as a simultaneous attack with as many applicators as possible being brought to bear.
Operators must be adequately protected and positioned to obtain down wind line-of-sight
application, with the powder jet slightly depressed below the horizontal. Powder jets should be
swept rapidly back and forth over the entire fire area. The direct impact of powder jets on pool
surfaces or leaks should be avoided. Where possible, powder should be aimed at vertical surfaces
immediately behind the seat of the fire.
The high discharge rate hoses are as much as one man can handle and the reaction force and
consequences of wasting or misdirecting powder requires that great care be taken in their use.
If the above techniques are adopted, tests have shown that LNG fires can be readily extinguished.
In fact extinction has often proved unexpectedly easy.
Re-ignition of LNG and vapour by burning paintwork, or other sources, must be expected. Water
sprays should be activated as soon as possible to cool steel work and speed vaporisation.
Gas smothering systems
Although CO2 and nitrogen smothering systems are not suitable for use in exposed open air
applications, they are otherwise the most efficient agent for fighting liquid and vapour fires. By
diffusing in a burning mixture, they lower the oxygen content and render the mixture inert. If the
flames can be separated from the liquid, the boil-off rate will also be reduced.
Nitrogen is more effective and less dangerous to personnel than CO2 but CO2 is more easily
How to tackle LPG fires ?
The highest priority of action must be given to stopping the gas flow to limit the amount of flammable
material available, and contain the fire in as small an area as possible. This may happen automatically
with the operation of the Emergency Shut Down System. Fire fighters must wear protective clothing
and self-contained compressed air breathing apparatus. Tackling the fire requires the use of two
media, water and dry powder.
Large quantities of water spray are to be used:
- To protect fire fighters and those assisting the rescue of trapped personnel from spaces.
- To cool surfaces exposed to heat.
- To prevent heat radiation through steel bulkheads.
The normal extinguishing medium for LPG fires is dry powder, which is propelled by nitrogen. The
Master is to ensure that all Officers are familiar with the operation of this equipment, and the technique
to be used in fighting a LPG fire.
The best results are achieved by applying dry powder at a maximum rate by using as many guns as
possible from upwind. The guns must sweep rapidly backwards and forwards over the fire area. If a
liquid spillage is involved, the surface of the spillage must not be disturbed by direct impact.
Dry powder guns discharge at not less than 4 kilos per second. The initial recoil and subsequent force
exerted by discharge means that in order to avoid the wastage of dry powder, a second person may be
needed to help the operator maintain control of the gun.
If it is judged preferable to allow a flame to burn from a controlled leak, such as a pipe fracture, water
spray is to be used to contain the fire without extinguishing the flame.
Either CO2 or Halon are fitted to the Cargo Control Room, Compressor Room and Motor Room on LPG
General precautions and instructions for gas carrier
- Fire fighting procedure for gas carrier
- Sources of ignition - portable electrical equipment
- Ship / shore insulating, earthing and bonding requirement
- Various fire extinguishing agents for LPG carriers
- Cargo machinery room precautions
- Fire fighting plan for LNG cargo
- LNG spill risk during marine transportation
Safety equipment for gas carriers
Training requirement for gas carriers
Fire fighting plan for gas carriers
Cargo emergency shutdown procedure for LNG carriers
Liquefied natural gases (LNG) -marine transport & accidents in LNG tankers
Liquefied gas carrier safety training
// Home page///
LNG handling ///
Sea transport ///
///Emergency response ///
Copyright © Liquefied Gas Carrier.com All rights reserved.
The content published in this website are for general reference only. We have endeavoured to make the information
as accurate as possible but cannot take responsibility for any errors. For latest information please visit www.imo.org .
Any suggestions, please Contact us !
///Links &Resources //