On 6 July 1988, a massive leakage of gas condensate on Piper Alpha ignited, causing a series of catastrophic explosions and fires. The heat from the initial fires ruptured the riser of a gas pipeline fed to Piper Alpha from another installation, which produced a further massive explosion and fireball that engulfed the Piper Alpha platform. 

Investigators concluded that a release of light hydrocarbon condensate occurred when a pump was restarted after having been prepared for maintenance. Unknown to the workers starting the pump, a relief valve in the pump discharge had been removed for maintenance and a blank loosely installed in place of the relief valve. When the pump was started, this blank leaked, producing a flammable cloud that subsequently found an ignition source. The pump was started at about 10pm and by 1am the platform had been entirely destroyed.

Of the 226 people on the platform at the time of the event, 165 died, along with two emergency responders during the rescue attempt.

Root Causes:

Communications – Inadequate Handover:

• There was a lack of communication between maintenance staff and the platform's crew as to the current status of plant equipment.
• Handovers between shifts had degraded to informal communications between workers resulting in key information on the status of the relief valve being missed.

Management System Failures - System, Procedures and Administrative Controls Inadequacy

• Permit to Work: A failure to control work permit material associated with the pump resulted in key information relating to the relief valve being missed by night shift operations, who operated the condensate pump believing it was safe to do so.
• Quality Control and Auditing: No regular auditing of the permit to work system was conducted onboard, which allowed gross deficiencies in the system to go unchecked.

Equipment Difficulty – Engineering and Design Failings

• The proximity of the control room and accommodations to production modules coupled with an inadequate blast wall meant that the explosion had catastrophic impacts on the accommodations and provided little time for the crew to initiate emergency response and evacuation procedures.