Fire in a crude oil storage tank, BP oil Dalmeny, Scotland. 11th June 1987

Accident summary

On 11 June 1987 a team of four contractors was cleaning a crude oil storage tank at the Dalmeny Oil Storage Terminal. The tank was of the floating roof type and the roof had been lowered due to the tank being empty. It was resting on a series of 219 support pillars. Three of the contractors worked inside the tank with one on duty outside along with a BP employee.

The tank had been emptied of its contents and three roof manhole covers opened to allow natural ventilation. However, the evolution of a vapour with the risk of forming an explosive atmosphere was not considered sufficient to merit either mechanical ventilation or rigorous monitoring of the vapour concentrations within the tank. As a precaution though, the workers were required to wear airline-breathing apparatus supplied by a compressor located outside the tank bund.

At 13:20 hours the outside man looked in and saw a ring of fire surrounding the three men. Two of the employees managed to escape the fire but the third man died from the effects of asphyxiation and burns. The fire escalated rapidly with flames and smoke coming out of the open man ways.

The cause of the accident was one of the contractors smoking inside the oil tank. It was apparently common practice for the workers to remove their breathing apparatus while inside the tank, with some workers choosing to smoke while the supervisor was not looking. On this occasion one of the men working in the tank had dropped a lit cigarette on to the floor where it had ignited the crude oil.

Failures in technical measures

• Several workers disregarded basic safety procedures, resulting in a lit cigarette being dropped inside the storage tank.
  Terminal rules required all matches and lighters to be surrendered at the security gate, but this was not enforced.
• Maintenance Procedures^[17]: management / supervision
• Site Security^[18]: control of ignition sources brought onto site
• Hazardous Area Classification / Flameproofing^[19]: ignition sources identification and elimination
• No forced ventilation of the tank to reduce the flammable vapour concentration was considered necessary.
• Maintenance Procedures^[20]: isolation / draining / flushing
• The contracting staff working inside the storage tank had not been properly informed of the toxic risks of working without the appropriate breathing apparatus and the potential for a flammable vapour at the oil surface.
• Training^[21]: maintenance training
• The management of the contractors and the contracting company by both the contractor and BP could have been more thorough.
• Maintenance Procedures^[22]: management/supervision
• Isolation^[23]: emergency isolation

References

Health and Safety Executive, 'The fires and explosion at BP Oil (Grangemouth) Refinery Ltd. A report of the investigations by the Health and Safety Executive into the fires and explosion at Grangemouth and Dalmeny, Scotland, 13 March, 22 March and 11 June 1987', ISBN: 0 11 885493 3, 1989.