Kindly advise the emergency procedures if a 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?
Answers
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11/08/2015
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Sudhakara Babu Marpudi, Dangote Oil Refinery Company, m_sudhakarababu@yahoo.com
Most refineries / LPG terminals will have the equipment for offloading the toppled tanker material into another tanker. Contact the nearest Refinery / LPG terminal for this. Leak or no leak the toppled tanker must be cordoned off till the tanker is emptied. In case there is a large leak, some turbulence must be created to avoid formation of vapor cloud. Water from a fire tender truck can be used for this. Small / minute leaks will evaporate themselves. Check and eliminate the ignition sources (kitchen fires etc.,) in the down wind side of the LPG leak.
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29/05/2015
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keith bowers, B and B Consulting, kebowers47@gmail.com
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 vapor clouds which will DETONATE with very high 'over-pressure. Mixed butanes will form a vapor 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 vapor clouds.
IF a tanker is not leaking , the contents should be removed (pumped out) before anything is done to move or upright the tanker. Small leaks must be evaluated to determine if they can safely be reduced or stopped. A big 'fan' should be used to dissipate any vapor cloud before approching 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 vapors. 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 vapor 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 mobil equipment away from the danger zone.
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