Gas Detection On Off-Shore Platforms

By Geoff Wilson

Twenty years ago, fire swept through the Piper Alpha oil rig in the Scottish sector of the North Sea. Panic and confusion were the order of the day as the doomed installation buckled into the frigid water. One of the findings in a public inquiry into the disaster, headed by Lord Cullen, who is one of Scotland’s senior judges, was that the gas detection system alarmed before the explosion. The explosion cost the life of 167 men and insured loss of £1.7 billion (US$ 3.4 billion).

The disaster began with a routine maintenance procedure. On the morning of the 6th of July, 1988, a certain backup propane condensate pump in the processing area needed to have its pressure safety calve checked. The work could not be completed by 18.00 and the worker asked for and received permission to leave the rest of the work until the next day.

Later in the evening during the next work shift, the primary condensate pump failed. None of those present were aware that a vital part of the machine had been removed and decided to start the backup pump. Gas product escaped from the hole left by the valve.