Piper Alpha significant event explosion
Piper Alpha was an oil platform located in the North Sea about 120 miles (190 km) north-east of Aberdeen, Scotland. It was operated by Occidental Petroleum (Caledonia) Limited (OPCAL) and began production in 1976, initially as an oil-only platform, but later converted to add gas production.
Piper Alpha exploded and sank on 6 July 1988, killing 165 of the men on board, 30 of whose bodies were never recovered, as well as a further two rescue workers after their rescue vessel, which had been trapped in debris and immobilised, was destroyed by the disintegrating rig. Sixty-one workers escaped and survived. The total insured loss was about £1.7 billion (£5 billion in 2021), making it one of the costliest man-made catastrophes ever. At the time of the disaster, the platform accounted for roughly 10% of North Sea oil and gas production. The accident is the world's worst offshore oil disaster in terms of lives lost and industry impact. The inquiry blamed it on inadequate maintenance and safety procedures by Occidental, though no charges were brought.
In Aberdeen, the Kirk of St Nicholas on Union Street has dedicated a chapel in memory of those who died, containing a Book of Remembrance listing them. A memorial sculpture is located in the Rose Garden of Hazlehead Park.First explosion and initial reactions
21:55: The first explosion occurred due to condensate leak from the PSV flange. Condensate pump A was switched on. Gas flowed into the pump, and because of the missing safety valve, produced an overpressure, which the loosely fitted metal disc did not withstand. Gas audibly leaked out at high pressure, drawing the attention of several men and triggering six gas alarms, including the high-level gas alarm. Before anyone could act, the gas ignited and exploded, blowing through the firewall made up of 2.5 by 1.5 m (8 by 5 ft) panels bolted together, which were not designed to withstand explosions. The explosion almost entirely destroyed the control room, killing key personnel responsible for coordination of the rig. Custodian Geoff Bollands, who had been in the room and witnessed the alarms going off, survived the blast and immediately activated the rig's emergency stop button before escaping, closing huge valves in the sea lines and ceasing all oil and gas extraction.Theoretically, the platform would then have been isolated from the flow of oil and gas and the fire contained. However, because the platform was originally built for oil, the firewalls were designed to resist fire rather than withstand explosions. The first explosion broke the firewall and dislodged panels around module (B). One of the flying panels ruptured a small condensate pipe, creating another fire.22:04: The control room of Piper Alpha was abandoned. A mayday call was signalled via radio by radio operator David Kinrade.  Piper Alpha's design made no allowances for the destruction of the control room, and the platform's organisation disintegrated. No attempt was made to use loudspeakers or to order an evacuation. Despite Bollands' activation of the emergency stop, no alarms warned workers of the unfolding disaster, as many of their systems had been destroyed by the initial blast.
22:05: The Search and Rescue station at RAF Lossiemouth received its first call notifying them of the possibility of an emergency, and a No. 202 Sqn Sea King helicopter, "Rescue 138", took off at the request of the Coastguard station at Aberdeen. The station at RAF Boulmer was also notified, and a Hawker Siddeley Nimrod maritime patrol aircraft from RAF Kinloss was sent to the area to act as "on-scene commander" using the designation "Rescue Zero-One".
22:06: The heat from the flames ruptured crude-oil storage tanks in module B, flooding the area with crude oil, which ignited almost instantaneously, creating a black plume of smoke characteristic of oil fires, visible from nearby ships. The burning oil later dripped onto a lower platform used by the rig for diving operations. The platform floor consisted of steel grates, and under normal circumstances would have allowed the burning oil to drip harmlessly into the sea, but divers on the previous shift had placed rubber matting on the metal grate (likely to cushion their bare feet from the sharp metal grates), allowing the oil to form a burning puddle on the platform.Subsequent explosions
22:20: The heat from the burning oil collecting on the diving platform caused the nearby Tartan pipeline, pressurised to 120 atmospheres, to rupture violently, releasing 15-30 tonnes (10,000 to 30,000 m3 (350,000 to 1,060,000 cu ft) per second of its highly flammable contents at immense pressure, which immediately ignited into a massive fireball, the heat and vibrations of which were felt by the crews in vessels as far away as 1 km from the rig. From that moment on, the platform's destruction was inevitable.
22:30: The Tharos, a large semi-submersible firefighting, diving/rescue, and accommodation vessel, drew alongside Piper Alpha. The Tharos used its water cannon where it could, but it was restricted, because the cannon was so powerful, it would injure or kill anyone hit by the water. Tharos was equipped with a hospital with an offshore medic assisted by diver paramedics from the Tharos saturation diving team.  A triage and reception area were set up on the vessel's helideck to receive injured casualties.
22:50: The MCP-01 pipeline failed and exploded, shooting huge flames over 300 ft (90 m) into the air. The Tharos was driven off by the heat, which began to melt the surrounding machinery and steelwork. Only after this explosion did the Claymore platform stop pumping oil. Personnel still left alive were either desperately sheltering in the scorched, smoke-filled accommodation block or leaping from the various deck levels, including the helideck, 175 ft (50 m) into the North Sea. The explosion destroyed a fast rescue boat launched from the standby vessel Sandhaven that had been trapped in debris during a rescue attempt, killing nearly all of the crewmen on board with the exception of driver Ian Letham, as well as the six Piper Alpha survivors whom they had rescued from the water. Sandhaven was the standby vessel for Santa Fe 135, several miles away.
23:18: The Claymore gas line ruptured and exploded, adding even more fuel to the already massive firestorm on board Piper Alpha. With thousands of cubic metres of highly volatile fuel burning every second, the 20,000-tonne steel platform melted over the next 80 minutes.