110 likes | 836 Views
A reminder: Flixborough disaster. 1 June 1974, 35 Years ago…. An expansion bellows failed releasing 30 tons of flammable cyclohexane which formed a vapour cloud that ignited. The explosion killed 28 people and injured 89. The entire plant was destroyed and never restarted.
E N D
A reminder: Flixborough disaster 1 June 1974, 35 Years ago… • An expansion bellows failed • releasing 30 tons of flammable cyclohexane • which formed a vapour cloud that ignited. • The explosion killed 28 people and injured 89. • The entire plant was destroyed and never restarted. • 1821 homes were damaged
Temporary pipe connection that failed was between these points: Pipe installed to bypass a reactor which was removed for repairs.
The modification that failed… Bellows Bellows Scaffold installed for the temporary pipe to rest on Forces on pipe due to change of momentum around bend
Lessons learnt on bellows: • Bellows are designed to take internal pressure but cannot take any other strain! • Bellows require proper support on both ends! • Follow manufacturers recommendations! • In this case: • A 500 mm pipe, so significant weight (>2 tons?) • There were also bends in the pipe which would cause sideways forces due to the change in momentum
Management of change….. • No proper mechanical design review was done: Bellows manufacturer recommendations not followed. • A temporary MOC requires the same attention as a permanent one