Piper Alpha Oil Platform Inferno
An analysis of the fire and explosion on the Piper Alpha oil platform
At 6:00 PM on 6th July 1988 maintenance workers on the oil platform Piper Alpha sought permission to stop work on a backup propane condensate pump, leaving a hole in the pump where a valve had been.
Just before 10:00PM the primary propane condensate pump failed. Workers on the next shift were unaware that the backup pump was inoperative, and started the backup pump.
The first explosion was caused by gas escaping from the hole in the pump where the valve should have been, and was followed twenty minutes later by a larger explosion.
The failure of the firewalls separating different parts of the facility, a secondary failure since they were never designed to cope with an explosion, ignited the oil stores.
The automatic deluge system was turned off at the time of the incident, and otherwise may have prevented the fire from spreading. The decision had been taken that the the system would be turned off whenever divers were in the water in order to protect those divers if they neared the intakes.
At approximately 10:20PM the gas risers on the other platforms burst. These gas risers were pipes between 24 and 36 inches in diameter, carrying gas at 2000 pounds per square inch, creating the inferno.
The lack of inter-platform communication led to the other platforms continuing to pump gas through the risers on the assumption that a lack of communication meant that Piper Alpha was dealing with the problem, not providing a failsafe system. The gas risers were shut off approximately an hour after bursting.
The accommodation area was seen by many as the safest place to await rescue, due to some separation from the processing. While it may have been the furthest point from the fire, it was not smokeproof. For those who chose to stay, the decision proved fatal, and many personnel were saved after jumping into the sea.
The fire was visible from 85 miles and felt at 1 mile. Almost all of the platform was melted off or down to sea level. 167 personnel died, 165 out of the 226 onboard the platform, plus 2 from a rescue vessel.
Other factors seen as adding to the seriousness of the incident included: there had been no full safety drill in the last three years, the training and safety procedures were lacking, there were many new staff unfamiliar with the layout of the platform, and that problems raised by safety audits had not been fixed.
Fix?
If the permit to work system had been effective, the backup pump may not have been started or been able to be started.
Similar?
The Phillips 66 polyethylene explosion was also caused by faulty maintenance activities.
This case study is used in the training course "Safe Systems: Procure, Analyse, Develop, Operate"