Buncefield: A Survey of the Extent and Significance of Blast Damage

Synopsis

In the early morning on 11th December 2005 CCTV cameras in the Buncefield Oil Terminal and in the surrounding industrial estates captured remarkable images showing the spread of a low lying dense cloud of petrol vapour. After 25 minutes the cloud was 2-3 metres deep and covered an area up to 500 metres across. A devastating vapour cloud explosion then occurred which caused damage in excess of £1 billion. Buildings, storage tanks and other plant on the site itself were completely destroyed by fire and blast damage. All other buildings in the area that the cloud reached were catastrophically damaged and the remains of several large reinforced concrete office and factory buildings had to be demolished. Further away from the site there was significant damage to the cladding of scores of other commercial properties. Many were not usable and had to be completely reclad. The economy of the whole area was blighted for several years. Fortunately there were no fatalities.

Unfortunately Buncefield was not a one-off. There have been two further explosions in low lying vapour clouds around petrochemical sites since 2005. In these cases the cloud spread further causing damage similar to Buncefield but over a much wider area. Around 70 people were killed – mostly members of the public. Graham Atkinson’s talk will include a brief survey of the damage to buildings and other objects in and around the sites focussing on the strong correlation between the degree of damage and the distance to the edge of the cloud. The structural damage caused is clearly of use in assessing the likely impact of further incidents but also plays an important part in advancing fundamental understanding of the mechanism of explosion. This is still a subject of active research effort.

A great deal of work was carried out on collecting and analysing available evidence from the incident in order to understand the explosion mechanism and estimate the overpressure levels within the gas cloud that formed. This included field objects which could be used as overpressure indicators on the site located within the area covered by the vapour cloud which suffered varying degrees of damage. A series of tests were commissioned after the event in order to compare the damage of the field objects with controlled static and dynamic tests on similar objects. The second part of the presentation reports on numerical studies of the damaged objects, particularly switch boxes, subjected to both detonation and deflagration scenarios and the assessment of the response of those objects in order to aid the investigation of the explosion. The study has also been extended to the response of a portal frame structures outside the gas cloud which suffered varying degrees of damage in order to try and provide some guidance on the safe siting of industrial type structures from oil storage facilities.

About the speakers

Dr Graham Atkinson

Graham Atkinson has worked for HSE for 23 years. His responsibilities include investigation of industrial fires and explosions and experimental research in the area of industrial fire and process safety. In 2010 he won the Hutchison medal (IChemE) for forensic work done at the site of the Buncefield vapour cloud explosion.

Dr Luke Louca

Luke Louca is a Reader at Imperial College London. His main research interests lie in the behaviour of structures and materials subjected to impact and explosions. His work has been funded by EPSRC, Dstl (MoD), US Office of Naval Research (ONR), HSE, UK Offshore Operators Association, Shell, BP and British Gas.

Further information

This evening meeting is organised by SECED and chaired by Prof Ahmed Elghazouli (Imperial College London). Non-members of the society are welcome to attend. Attendance at this meeting is free. Seats are allocated on a first-come-first-served basis. For further information, please contact Greg James (tel. 020 7665 2229).