Valero Energy UK and B&A Contracts have been fined £5 million after a storage tank explosion killed four workers and seriously injured another at a Pembrokeshire oil refinery in 2011.
Dennis Riley, 52, Robert Broome, 48, Andrew Jenkins, 33, and Julie Jones, 54, died after the tank exploded at the site. Andrew Philips also sustained major injuries.
Swansea Crown Court heard how on June 2, 2011, the five workers were emptying a tank in the amine recovery unit using a vacuum tanker when the explosion and subsequent fire took place. B&A Contracts, which was a long-term contractor at the refinery, was carrying out the work, with support from another contractor, Hertel.
The explosion resulted in a fireball that severed the five-tonne tank roof, and this was projected 55 meters to impact against a butane storage sphere. The roof narrowly missed a pipe track where a range of flammable materials were carried.
At the time of the incident the refinery was operated by Chevron, but ownership changed in August 2011 when the sale to Valero was completed. Chevron will pay the fine and court costs after coming to an agreement with Valero Energy.
A Health and Safety Executive investigation found the explosion was most likely to have been initiated by the ignition of a highly flammable atmosphere within the tank, during what should have been a routine emptying operation in preparation for further cleaning and maintenance.
The investigation found there has been longstanding failures within the refinery safety management systems and as a result the risks posed by flammable atmospheres within the amine recovery unit were not understood or controlled.
Valero Energy UK pleaded guilty to breaching sections 2(1) and 3(1) of the Health and Safety at Work Act 1974. The company has been fined £5 million and ordered to pay costs of £1 million.
B & A Contracts in Pembrokeshire pleaded guilty to sections 2(1) and 3(1) of the Health and Safety at Work Act 1974. They have been fined £120,000 and ordered to pay costs of £40,000.
HSE inspector Andrew Knowles says: ‘This incident, which had devastating consequences for all of 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.’