Valero Energy UK Ltd and B&A contracts Ltd have been fined after an explosion killed four workers and seriously injured another at an oil refinery in Pembrokeshire in 2011.
The Court heard that on 2 June 2011 five workers were emptying a tank in the Amine Recovery Unit using a vacuum tanker when the explosion and subsequent fire occurred. The explosion resulted in a fireball which severed the 5-tonne tank roof which was then projected 55 metres to hit a nearby butane storage sphere. The piece also narrowly missed a pipe track where a range of flammable materials were carried.
B&A Contracts, a long-term contractor at the refinery, was carrying out the work with the support from another contractor company, Hertel.
An investigation carried out by the Health and Safety Executive (HSE) found that the explosion was most likely to have been initiated by the ignition of a highly flammable atmosphere in the tank. Emptying the tank for further cleaning and maintenance should have been a routine task.
The investigation also found that there had been longstanding failures within the refinery safety management systems. As a result risks posed by flammable atmospheres within the Amine Recovery Unit were not controlled or understood. At the time of the incident, the refinery was operated by Chevron Ltd, but ownership changed in August 2011 upon completion of the sale to Valero.
Valero Energy UK Ltd pleaded guilty for breaching provisions of the Health and Safety at Work Act 1974. The Company was fined £5 million pounds and ordered to pay costs of £1 million.
B&A Contracts Ltd was fined £120,000 and ordered to pay costs of £40,000, for the same breaches of the Health and Safety at Work Act 1974.
Speaking after the hearing, HSE inspector Andrew Knowles said "this incident, which had devastating consequences for all those involved, was entirely preventable. Many opportunities to take action to control risk were missed, that would have prevented the incident from occurring. It is important to realise that the incident could have had even more serious consequences had the butane sphere or pipe track been damaged by the flying tank roof."
