Catalogue description Health and Safety Executive: Inquiry into the Disaster which Occurred at Nypro (UK) Ltd, Flixborough: Unregistered Records

At about 16:53 hours on Saturday 1 June 1974 the Nypro (UK) site at Flixborough was severely damaged by a large explosion. Twenty-eight workers were killed and a further 36 suffered injuries; the number of casualties would have been more if the incident had occurred on a weekday, as the main office block was not occupied. Prior to the explosion, on 27 March 1974, it was discovered that a vertical crack in reactor No.5 was leaking cyclohexane. The plant was subsequently shutdown for an investigation. It identified a serious problem with the reactor and the decision was taken to remove it and install a bypass assembly to connect reactors No.4 and No.6 so that the plant could continue production. During the late afternoon on 1 June 1974 a 20 inch bypass system ruptured, which may have been caused by a fire on a nearby 8 inch pipe. This resulted in the escape of a large quantity of cyclohexane. The cyclohexane formed a flammable mixture and subsequently found a source of ignition. At about 16:53 hours there was a massive vapour cloud explosion which caused extensive damage and started numerous fires on the site.

The Secretary of State for Employment, Michael Foot, set up a public inquiry to investigate the causes of the accident; the report of the inquiry was published by HMSO in 1975.