Detonations in industrial vapour cloud explosions

Not all accidental releases of flammable gases and vapours create explosions; most releases do not find an ignition source and of those that do ignite, most of them generate low or moderate overpressure only (deflagrative combustion). However, when certain conditions are satisfied, deflagration to detonation transition (DDT) can occur followed by stable detonation. Although a detonation is a rare event, it is a worst-case accidental event. Items within the detonating cloud are destroyed or rendered unusable. An intense vapour cloud explosion (VCE) occurred at the Buncefield fuel storage site in 2005. Extensive research into this incident revealed that detonation had taken place in the vapour cloud and had propagated over a large unconfined and uncongested area. Unique data were collected on the impact of blast on items of industrial plant, vegetation and vehicles. Combined with advances in fundamental knowledge of detonation science and large-scale tests on detonations, these new insights have allowed a comprehensive interpretation of the multitude of previous accidents involving intense vapour cloud explosions. The review identifies beyond reasonable doubt that in several past industrial accidents detonation was the cause of major destruction and loss of life. To our knowledge, a review of this kind is timely and is primarily designed for the awareness of engineers who may not be familiar with the investigation and its implications for previous accidental events. Some ideas are presented for safety management procedures to minimise the detonation risk.