Fifteen people were killed and almost 200 injured.
A distillation column and a blowdown tank had been overfilled with liquid hydrocarbons during a restart. This caused a major leak, followed by ignition and explosion of the gas cloud which formed.
In addition to the fatalities, the explosion and fire caused huge material damage in and around the refinery.
The accident helped to highlight the link between management and major accidents, after an inquiry found it was primarily caused by organisational and safety deficiencies at every level in BP.