Hazard analysis for a storage sphere of pressurised liquefied flammable gas

An analysis has been carried out on the fire and explosion risk associated with a storage sphere holding some 600 tons of liquefied flammable gas under pressure and protected by a spray system. Fault trees leading to (i) a large leakage followed by a catastrophic explosion of a flammable vapour cloud in the open, and (ii) a fire causing sudden rupture of the tank and a large fireball, have been constructed. Special attention is paid to the life risk to firemen who may be dealing with a fire incident at the sphere. Data for insertion in the fault trees are discussed and a cost benefit analysis of treevarious fire defence methods is carried out.