In March 1974, the Nypro plant in Flixborough detected a crack in a reactor. The plant is shut down, then the reactor is removed. To continue production, a bypass line is installed between the two neighboring equipment. This interim solution changes the actual operation of the plant.
On the 1st of June, the bypass broke. A large amount of cyclohexane escapes, forms a flammable mixture and finds a source of ignition. The explosion destroyed the site. Twenty-eight workers were killed, and the damage extended to nearby buildings.
The Health and Safety Executive’s assessment highlights what is missing before recommissioning: a full assessment of the consequences, sufficient calculations, a drawing of the proposed modification and a pressure test. The study also retains uncertainty about the precise triggering of the rupture.
Driving had to get around a known problem. Resumption of production did not prove that this interim change had retained the security of the system.
What we know
The initial mechanism of rupture retains uncertainty in the HSE study.
To go to the source
References accessed October 11, 2026. Linked pages may be in another language.
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