Lessons Learned from 40 Years of Accident Investigations

Over the last 40 years, GexCon has been involved in some important gas release, fire  and explosion experiments which were largely carried out on our test facility on the Norwegian island of Sotra and were aimed at increasing our understanding of dispersion, fire and explosion phenomena, providing validation of the predictive capability of explosion modelling, and understanding consequences of event sequences leading to major accidents. GexCon has also investigated many explosion accidents across both onshore and offshore around the world including some well-known accidents such as Piper Alpha, Buncefield, and many others, recently including some in the Middle East.

This paper discusses gas releases, explosions, how they eventuate in major hazard facilities both onshore and offshore, how they escalate and how consequences are evaluated. We then review two of the major accident investigations carried out by GexCon: one involving a gas explosion onshore and the other involving an oil mist explosion inside a large tank.

The paper goes through the often convoluted sequence of events and failures that lead to the two  accidents focussing on issues relevant to explosions. We discuss how these investigations were supported with computational fluid dynamics simulations (CFD). We review some of the most important lessons learned from each of these accidents as well as common factors with other previous accidents investigated, including the effect of congestion and confinement on gas explosions, the effect of the  type of fuel, and some effective and ineffective mitigation measures, the response of materials in structures to loads arising from explosions as well as some unexpected outcomes of some design safety features.