Piper Alpha disaster is world’s deadliest offshore tragedy which claimed the lives of 167 people

It's been over 35 years since the world's deadliest offshore tragedy took place - 120 miles from the Scottish coast.

The Piper Alpha tragedy took place on July 6 1988 and cost 167 lives.

It took place on board an oil platform named the Piper Alpha, which began construction in 1976.

The North Sea construction was in operation between 1980 and its destruction in 1988, when it exploded and sank.

But what actually happened on that tragic day?

Wikimedia Commons/BBC

Late in the evening, a series of explosions ripped through the platform.

The men in the control room were knocked off their feet, whilst the men sleeping in their beds in the accommodation block were thrown to the ground.

The initial explosion in the gas compressor module caused a rupture in the oil separation module.

Witnesses reported a second flash and bang as a huge fireball exploded into the sky.

Ruptures throughout the rest of the structure caused further damage, even wiping out a rescue craft that had been sent to retrieve the workers.

Just over an hour after the first explosion, the platform began collapsing.

The main accommodation bunker, which was four floors high, fell into the sea, killing all 81 men sheltering inside.

By the next morning, three quarters of the construction had been destroyed and lay on the floor of the North Sea.

It took over three weeks for the fires to be extinguished.

Just under a year later on 26 March 1989, the remains of the Piper Alpha were toppled into the sea.

Of the 226 people on board that night, only 61 survived. Of those who perished, 109 died from smoke inhalation, 13 by drowning, with severe burns killing 11 people.

In four cases, no cause of death could be determined, and 30 bodies were never recovered.

STV

A public inquiry was set up shortly after the disaster, with the report's findings being published in November 1990.

Most evidence was collected from survivors giving testimony and from expert opinion.

With most of the Piper Alpha under the sea, it was difficult to determine what caused the initial explosion.

The inquiry concluded that the most likely cause of the first explosion was the release of as little as 30 kg of condensate (mainly propane) over thirty seconds through an unsecured blind flange.

In the years after the disaster, it became apparent how traumatising it had been for those who had survived.

Of the 36 survivors who were interviewed by a professor in 1998, it was found that more than 70% displayed symptoms of PTSD.