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The next major hazard challenge: controlling the onset of detonation - Hazardex 2016

Author : Vincent H Y Tam and Mike D Johnson, DNV GL

29 October 2015

**This paper will be presented at Hazardex 2016. Contact us for details of delegate packages & offers**

The development trend of offshore oil and gas production is towards deeper water and further to the north.  In practice, this translates to large facilities in deep water and more enclosed construction in the Artic regions.  For example, the sizes of recent FPSOs are larger than those a decade ago.  This change brings about an explosion hazards which hitherto not been considered in safety studies, namely detonation.

There are two types of gas explosion mechanisms that can generate overpressures and blast, e.g.  in the “unconfined” gas clouds on an FPSO.  Detonation is an energetic form which converts more of the energy of a flammable gas cloud to damaging overpressures and blast effects than the second type, a deflagration, which converts less of the energy to blast and only in the volumes of gas cloud occupied by congestion such as equipment and pipework.  The damage potential of a detonation is more severe and more extensive than that of a deflagration.

Current engineering design and risk assessment methods assume deflagration and for most hydrocarbons ignore detonation on the grounds that it has not been observed in industrial accidents.  This assumption works well for small facilities in shallower part of the North Sea Continental Shelf and in the Mediterranean Sea. 

However, there is mounting evidence from recent onshore incidents that detonation has occurred in accidents in the industry.  In addition to lessons from incidents, this paper describes potential options that could prevent the onset of a detonations, recent large scale explosion tests and current research programme that are underway at Spadeadam Testing and Research Centre which could provide the industry with better understanding of this detonation hazards and suggestions for tools to assess this risk.

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