The disaster began with a routine maintenance procedure. On the morning of the 6th of July, a certain backup propane condensate pump in the processing area needed to have its pressure safety valve checked. The work could not be completed by 18.00 and the workers asked for and received permission to leave the rest of the work until the next day. The tube was sealed with a plate.
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 products escaped from the hole left by the valve.
Gas audibly leaked out at high pressure, ignited and exploded, blowing through the firewalls. The fire spread through the damaged firewalls, destroyed some oil lines and soon large quantities of stored oil were burning out of control. The automatic deluge system, which was designed to spray water on such a fire in order to contain it or put it out, was never activated because it had been turned off.
About twenty minutes after the initial explosion, at 10:20, the fire had spread and become hot enough to weaken and then burst the gas risers from the other platforms. These were steel pipes of a diameter from 24 to 36 inches, containing flammable gas products at two thousand pounds per square inch of pressure. When these risers burst, the resulting jet of fuel dramatically increased the size of the fire.
The accommodations were not smoke-proofed, and the lack of training that caused people to repeatedly open and shut doors only worsened the problem. Conditions got so bad in the accommodations area that some people realized that the only way to survive would be to escape the station immediately. They, however, found that all routes to lifeboats were blocked by smoke and flames, and in the lack of any other instructions, they made the jump into the sea hoping to be rescued by boat. Sixty-two men were saved in this fashion; most of the other 167 who died suffocated on carbon monoxide and fumes in the accommodations area.
The generation and utilities module, which included the fireproofed accommodation block, slipped into the sea. The largest part of the platform followed it.
The whole accident took place in 22 minutes.
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