Luck helped mitigate Texaco fire
15 Jan 2000
A catalogue of errors that led to a massive explosion and fire at Texaco's refinery in Pembroke, south Wales, was matched by an extraordinary series of fortunate coincidences that prevented any fatalities, according to an exhaustive report from the Health and Safety Executive.
The explosion, in June 1994, injured 26 people and virtually destroying the site, which was owned and operated by the Pembroke Cracking Company (PCC), a 50:50 joint venture between Texaco and Gulf Oil's UK subsidiary. It involved the ignition of a cloud of hydrocarbons, had the force of four tonnes of high explosive and was heard 30 miles away.
After a thunderstorm on the morning of 24 June, every unit at the site was shut down except for the fluid catalytic cracker. Hydrocarbon fluids were diverted into a vessel on the cracker, whose outlet valve closed to prevent product loss. Operators later tried to open this valve, but although the control system showed the valve to be open, it was in fact still shut. Eventually, the operators realised that there was a problem and tried to vent the excess fluid to a flare, but the flare system had become overloaded and a corroded pipe gave way, releasing about 20 tonnes of vapour and liquid.
It was lucky it was a Sunday; the plant was lightly staffed. It was even luckier that a van full of contractors wasn't going very quickly; it was just about to drive into an area that the fireball rolled through. Workers receiving permits to work were even luckier; they left a building just minutes before the explosion, which demolished the building's walls and collapsed its concrete ceiling.
The explosion had far-reaching consequences. Apart from the 26 injuries, the refinery cost some £48million to rebuild. The HSE later prosecuted both PCC partners; they were fined a total of £200 000 plus some £145 000.
According to the HSE, several lessons can be drawn from the incident. Control systems should be set up to display an overview of the conditions of the process, including mass balances to point up any flow problems; where these occur, it adds, operators should be able to check mass and volume balances wherever flow or level problems occur.
