Hydrocracker Explosion And Hearth At BP Oil, Grangemouth Refinery
The Hydrocracker Explosion and Hearth at BP Oil, Grangemouth Refinery. 22nd March 1987
On Saturday 21 March 1987 the hydrocracker unit was being recommissioned following a routine shut down. Throughout the recommissioning a plant c&n petroleum equipment internship 2017 trip occurred. This was thought to be a spurious trip and the plant operators started to deliver up the unit to normal coal operating circumstances. From then on till the time of the incident the plant was held in stand by condition with no fresh feed.
At 07:00 hours the following morning there was a violent explosion and subsequent hearth. The explosion could be heard and felt up to 30km away. The explosion centred on a low strain (LP) separator vessel, V306, which was fabricated from 18mm steel plate and weighed 20 tonnes.
The investigation of the accident prompt that an air operated management valve on the high pressure (HP) separator had been opened and closed on guide management no less than 3 times. Liquid stage within the LP separator fell and the valve was opened. This action allowed the remaining liquid within the HP separator to drain away c&n petroleum equipment internship 2017 and for high pressure gasoline to interrupt by means of into the LP separator. As the pressure relief on the LP separator had been designed for a fireplace relief case, not gas breakthrough the vessel subsequently exploded.
The control valve did not close mechanically as a result of the low low level journey on the HP separator had been disconnected a number of years earlier. The operators didn’t belief the main degree management reading and referred to a chart recorder for a again up level reading. There was an offset on this chart recorder which led them to assume that the extent within c&n petroleum equipment internship 2017 the HP separator was regular.
Failures in technical measures
– Operators did not trust the studying given by the float gauge within the HP separator and the nucleonic stage indication was misread due to an offset on the chart recorder.
Upkeep Procedures: fault reporting systems
Management Techniques: sensors
Working Procedures: provision of complete written operating procedures
– The low low stage journey on the HP separator had been disconnected a number of years earlier when a plant modification had been made.
Plant Modification / Change Procedures: HAZOP
Alarms / Trips / Interlocks: stage measurement
– The LP Separator strain relief had been sized for a hearth case, not a gas breakthrough from the HP separator.
Relief Techniques / Vent Methods: sizing of vents, relief valves
– There have been no means of isolating the HP separator following an incident within the LP separator.
Isolation: emergency isolation
Well being and Security Executive, ‘The fires and explosion at BP Oil (Grangemouth) Refinery Ltd. A report of the investigations by the Well being and Security Executive into the fires and explosion at Grangemouth and Dalmeny, Scotland, 13 March, 22 March and eleven June 1987’, ISBN zero eleven 885493 three, 1989.