A reminder: Flixborough disaster

1
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

2
The damage
3
Temporary pipe connection that failed was between
these points
Pipe installed to bypass a reactor which was
removed for repairs.
4
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
5
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 (gt2 tons?)
• There were also bends in the pipe which would
  cause sideways forces due to the change in
  momentum

6
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