SOLUTIONS TO LPG GAS TANKER
EXPLOSIONS
1. LPG
stations should be located away from habitable areas and should be located in
open grounds and well-ventilated areas.
2. LPG
stations should be located along the main roads, which are considered safe for
LPG transport, or locations, which can easily be reached from the main road
without passing through populated areas.
3. Compliance
with fire safety requirements
4. Train staff (drivers and LPG
station personnel)
5. The
road tanker should be equipped with a RELIEF
VALVE to control or limit the pressure in the system. All tanks should be fitted with one or more PRESSURE RELIEF VALVE. The PRESSURE RELIEF
VALVE prevents explosion. Spring-loaded pressure relief valve type is
preferred.
·
ASME / ANSI PTC 25.3 standards,
Pressure relief
valve – (This is a general term, which includes safety valves, relief
valves and safety relief valves.)
A spring-loaded pressure relief valve which is
designed to open to relieve excess pressure and to reclose and prevent the
further flow of fluid after normal conditions have been restored. It is characterized
by a rapid-opening 'pop' action or by opening in a manner generally
proportional to the increase in pressure over the opening pressure. It may be
used for either compressible or incompressible fluids, depending on design, adjustment,
or application.
Safety valve - A pressure relief valve
actuated by inlet static pressure and characterized by rapid opening or pop
action.
Relief valve - A pressure relief device
actuated by inlet static pressure having a gradual lift generally proportional
to the increase in pressure over opening pressure.
Safety relief valve - A pressure relief
valve characterized by rapid opening or pop action, or by opening in proportion
to the increase in pressure over the opening pressure, depending on the application,
and which may be used either for liquid or compressible fluid.
European standard EN ISO 4126-1
Safety valve - A valve which
automatically, without the assistance of any energy other than that of the
fluid concerned, discharges a quantity of the fluid so as to prevent a
predetermined safe pressure being exceeded, and which is designed to re-close
and prevent further flow of fluid after normal pressure conditions of service
have been restored.
 |
| Figure: A Gas Tanker Truck with a SAFETY VALVE |
6. Regular leak check with soap water solution or a gas leak
detector.
7. If you have
a small leak on your gas tanker (steel tank), you can quite often do a
"get you out of trouble" repair by rubbing a bar of soap over the split/hole. This fills the gap with
soap and may give you a little more time to cope with the problem. This is not by any means a permanent fix but
may stem the flow of gas until a fire service arrive whiles you pump the gas
into another tank.
8. If
an oil
tanker is leaking:
The first step should
be to contact fire service and police so that they can arrange to visit you and
contain the leak. They will have the expertise to determine what course
of action is necessary and who to contact in case of an emergency. Once
you have called fire service, you can take basic steps to contain the leak and
reduce any possible impact by doing the following:
a) Wear
protective gloves before handling any items covered in fuel oil
b) If
possible, place a container under the leak to catch the oil
c) If there is a small crack in the tank from
which fuel is leaking, a bar of soap can be rubbed into the crack can
temporarily restrict the flow of oil.
9. Fire
protection materials such as “DETONATION SUPPRESSION SYSTEM (DSS™) OR EXPLOSION
SUPPRESSION SYSTEM” can be inserted into all types
of fuel storage tanks. It prevent or suppress explosions, alleviate blasts and
spread of fires in any fuel storage system caused by flammable weapons,
conventional explosives, fire or even other means such as sparking, maintenance
error, electrostatic discharge, crashes, or other type of accident. DSS™ enables
repair of fuel tanks (i.e., welding), even when the fuel tank is filled with
fuel.
10. Train
drivers and LPG station personnel on
the emergency response procedures. For example if an LPG road tanker is toppled
on the road. What is the procedure for salvage if it does not leak? What is to
be done if it leaks and catch or does not catch fire? What is to be done if it
forms a vapour cloud?
LPG is a non-specific term for a range of
light petroleum molecules, ranging from ethylene to pentane. Normally 'LPG'
tankers are transporting 95% propane of propane and butanes with some C-5's,
Propane will form vapour clouds which will DETONATE with very high
'over-pressure. Mixed butanes will form a vapour cloud that deflagrates with a
'woof' and low over-pressure. Both ambient temperature and product temperature
are important variables to consider in estimating how fast the material will
evaporate and form such vapour clouds.
The general actions to be followed are:
To stop the car engine
and notify the fire service and police as soon as possible.
IF a tanker is not leaking, the contents
should be removed (pumped out) before anything is done to move or upright the
tanker. Most LPG terminals will have the equipment for offloading the toppled
tanker material into another tanker. Contact the nearest LPG terminal for this.
Small leaks must be evaluated to determine if they can safely be reduced or
stopped (for example by rubbing a bar of
soap on the hole or using a sealant to seal the hole to stop the leak). A
big 'fan' should be used to dissipate any vapour cloud before approaching the
leak source and SBA equipment and appropriate PPE used in approaching the leak.
Minimal drips should be ventilated by
fans rather than any attempt to stop the leak, and the tanker contents removed.
Leaks large enough to create a liquid pool are best allowed to evaporate, with
fans dispersing the vapours. If a small leak has ignited and the flame is
confined to a small area, cooling the metal with water and then using CO2 to
extinguish the flame is appropriate.
If a leak has ignited, and the flame size is too large to approach for
extinguishing as above, prudence and personnel safety dictate clearing a safety
zone around the fire and drenching the metal exposed to the flame to keep its
temperature as low as possible to prevent tank rupture. Stationary fire
monitors should be setup to keep the fire water where needed and keep personnel
well removed. A safety zone of at least 300' is appropriate for Propane leaks
and fires, remembering a propane vapour cloud will often DETONATE with enough force to destroy nearby buildings and injure
or kill people.
Because the risk of tanker rupture is unknown, it is unreasonable to expose
personnel to that risk in attempting to slow or stop the leak or connect hoses
to pump out the contents. The unknowns of metal damage caused by the accident,
metal damage caused by the fire, and actual metal temperatures in the flame-affected
area, make it impossible to assess or evaluate the risk of tank rupture with
ANY reasonable level of confidence. Prudence dictates one must prepare for
tanker rupture at any moment and move people and mobile equipment away from the
danger zone.
11. Refer
to “Guide to Good Industry Practices - LP Gas Bulk Road Tanker Management by
WLPGA”
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