Interpretation of Damage Caused By a Vapour Cloud Explosion

Research over a period of forty years has provided a large amount of data on flame acceleration and pressure generation resulting from ignition of a vapour cloud engulfing a region of congested process pipework. More recently, research conducted following the Buncefield incident in 2005, the most extensive for any Vapour Cloud Explosion (VCE), led to the conclusion that the incident involved a transition from a deflagration to a detonation (DDT). In reaching this conclusion, several possibilities were considered and dismissed, including a speculative explosion mechanism not previously observed that involved ignition by radiation of dust particles ahead of the flame. An important element in reaching this conclusion was the evidence, in terms of damage and directional indicators, observed following the incident and two subsequent VCEs. It is important that the implications of forensic evidence observed in future investigations of VCEs are understood. The paper reviews the results obtained from the research and also provides structural response analysis for the pressure profiles that could be generated in a VCE involving a DDT.