Valero fined £5m following fatal Pembroke refinery explosion in 2011

Article by Amanda Doyle

The remains of the tank after the explosion

VALERO Energy has been fined £5m (US$6.4m) following an explosion at its Pembroke refinery in Wales in 2011, which killed four people and seriously injured another.

On 2 June 2011, B&A Contracts was carrying out what was supposed to be a routine operation along with support from another contractor, Hertel. Five workers were emptying tank 302 in the Amine Recovery Unit using a vacuum tanker in preparation for cleaning and maintenance. An explosion occurred at 18:19, killing Dennis Riley, Robert Broome, Andrew Jenkins, and Julie Jones. Andrew Philips sustained major life-changing burns.

The explosion caused a fireball that severed the 5 t roof of the tank, projecting it 55 m away where it impacted with a butane storage sphere. The roof narrowly missed a pipe track where flammable materials were carried. Jenkins had been standing on top of the tank and Jones was on a platform between tanks 302 and 303, according to reporting of the Swansea Crown Court proceedings by local news site The Milford Mercury. Phillips and Broome were on the ground, and Riley was sitting on a kerb making notes. According to BBC coverage of the proceedings, Phillips described how he was standing further back than his colleagues when the explosion occurred, and how he remembered being covered in flames as he ran through the fire.

The HSE investigation found that the explosion was most likely triggered when a flammable atmosphere within the tank ignited. The court heard how an unearthed hosepipe was likely to have caused the spark. The HSE found that the risk posed by flammable atmospheres within the Amine Recovery Unit were not understood or controlled. It also found that there had been longstanding failures with safety management systems. According to BBC, the court heard that the flammable gas levels in the tank had been checked a few days prior to the incident, but that the results were either not communicated or understood.

Chevron owned the refinery at the time of the incident, but ownership changed to Valero in August 2011. The sale deal had been agreed before the accident occurred. Valero and B&A Contracts both pleaded guilty to breaching HSE regulations on ensuring the health and safety of employees. Valero has been fined £5m and ordered to pay prosecution costs of £1m. However, the fine and the costs will be paid by Chevron.  B&A contracts has been fined £120,000 and ordered to pay costs of £40,000.

HSE inspector Andrew Knowles said: “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.”

Detective Superintendent Anthony Griffiths said: “Officers from Dyfed-Powys Police worked closely with the Health and Safety Executive to support them in the very complex investigation to establish the cause of this tragic incident. We hope that the lessons learned ensure that a tragedy of this nature doesn’t happen again. Our thoughts remain with all the families involved.”

Article by Amanda Doyle

Staff Reporter, The Chemical Engineer

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