skip to Main Content
Slide 03
UK – HSE Releases Final Report Into Fatal 2011 Chevron Refinery Explosion

UK – HSE Releases Final Report Into Fatal 2011 Chevron Refinery Explosion


The HSE has released its report into the June 2011 explosion at Chevron’s Pembrokeshire refinery which killed four people. The report gives an overview of the incident and details the underlying causes behind the incident, as well as offering safety management lessons for industry.

In June 2019, Chevron paid a £5 million fine and court costs of £1 million as part of a deal it struck with Valero Energy UK Limited, which bought the site shortly after the disaster. Specialist tank cleaning firm B&A Contracts, which employed the four contractors who were killed, was fined £120,000 and ordered to pay £40,000 in legal costs. Other than the fatalities, a fifth worker caught in the fireball survived but with life-changing burns.

When passing sentence on the defendants at Swansea Crown Court on 6 June 2019, the Judge, the Honourable Mr Justice Lewis, stated: “The fact is that the serious nature of the failings, the number and range of failings, and the length of time over which certain of the failings occurred demonstrate serious errors and serious failures within the organisation to address the risks to health and safety. All major hazard industries should look carefully, both at their own operations and the control of contractors, in the light of the systematic failings that lay behind this tragic incident.

“I hope that this prosecution will serve as a reminder to those with a responsibility for employees and contractors, to actively monitor their safety management system arrangements to ensure they are effective in keeping workers safe.”

The HSE’s report details how on June 2, 2011, an atmospheric storage tank within the amine regeneration unit at the Chevron Pembroke Refinery exploded. The force of the explosion ejected the five-tonne steel tank roof over 55 metres through the air. After narrowly missing a multi-fuel pipe track, the roof crashed onto a pressurised storage sphere containing extremely flammable butane. Good fortune prevented the airborne roof from puncturing the butane storage vessel, which would have led to an uncontrolled release of liquified petroleum gas (LPG).

The explosion was caused by the unintended ignition of a flammable atmosphere within the tank (17T302), during what should have been a routine cleaning operation conducted in preparation for maintenance. The investigation revealed a longstanding and widespread failure to understand and control risks posed by the flammable atmosphere inside the tank. The explosion and the resulting fatalities were therefore avoidable. The incident was not merely the consequence of errors by individual employees, but because of the failure of safety management systems to ensure a safe place and safe systems of work.

The report is available in full on the HSE website:

Back To Top