Piper Alpha

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Piper Alpha was a North Sea oil production platform operated by Occidental Petroleum (Caledonia) Ltd.[1] The platform began production in 1976,[2] first as an oil platform and then later converted to gas production. An explosion and resulting fire destroyed it on 6 Jul 1988, killing 168 men,[3] with only 61 survivors. The death toll includes two crewmen of a rescue vessel.[4] Total insured loss was about £1.7 billion (US$3.4 billion). At the time of the disaster the platform accounted for approximately ten percent of North Sea oil and gas production, and was the worst offshore oil disaster in terms of lives lost and industry impact.[5]

The Kirk of St Nicholas in Union Street, Aberdeen has dedicated a chapel in memory of those who perished and there is a memorial sculpture in the Rose Garden of Hazlehead Park in Aberdeen. Thirty bodies were not recovered.

Contents

Piper oil field

Four companies that later transformed into the OPCAL joint venture obtained an oil exploration licence in 1972 and discovered the Piper oilfield located at 58°28′N 0°15′E / 58.467°N 0.25°E / 58.467; 0.25{{#coordinates:58|28|N|0|15|E||| | |name= }} in early 1973 and commenced fabrication of the platform, pipelines and onshore support structures. Oil production started in 1976 with about 250,000 barrels of oil per day increasing to 300,000 barrels (48,000 m3). A gas recovery module was installed by 1980. Production declined to 125,000 barrels (19,900 m3) by 1988. OPCAL built the Flotta oil terminal in the Orkney Islands to receive and process oil from the fields Piper, Claymore and Tartan, each with its own platform. One thirty inch (0.762 m) diameter main oil pipeline ran 128 miles (206 kilometres) from Piper Alpha to Flotta, with a short oil pipeline from the Claymore platform joining it some twenty miles (32 km) to the west. The Tartan field also fed oil to Claymore and then onto the main line to Flotta.[6] Separate 46 cm diameter gas pipelines run from Piper to the Tartan platform, and from Piper to the gas compressing platform MCP-01 some 30 miles (48 km) to the northwest.

Construction

A large fixed platform, Piper Alpha was situated on the Piper oilfield, approximately 120 miles (193 km) northeast of Aberdeen in 474 feet (144 m) of water, and comprised four modules separated by firewalls.[7] The platform was constructed by McDermott Engineering at Ardersier and UIE at Cherbourg, with the sections united at Ardersier before tow out during 1975, with production commencing in late 1976. For safety reasons the modules were organised so that the most dangerous operations were distant from the personnel areas. The conversion from oil to gas broke this safety concept, with the result that sensitive areas were brought together, for example, the gas compression next to the control room, which played a role in the accident. It produced crude oil and natural gas from 24 wells for delivery to the Flotta oil terminal on Orkney and to other installations by three separate pipelines. It has been said[by whom?] that at the time of the disaster, Piper was one of the heaviest platforms (along with Magnus and Brae B) operating in the North Sea.

Timeline of the incident

A new gas pipeline was built in the weeks before the 6 July explosion, and while this work disrupted the normal routine, the platform was operating as normal. The discovery of a small gas leak was not unusual and no cause for concern. Because the platform was completely destroyed, and many of those involved died, analysis of events can only suggest a possible chain of events based on known facts. Some witnesses to the events question the official timeline.[8]

12:00 p.m. Two condensate pumps, designated A and B, displaced the platform's condensate for transport to the coast. On the morning of July 6, Pump A's pressure safety valve (PSV #504) was removed for routine maintenance. The pump's fortnightly overhaul was planned but had not started. The open condensate pipe was temporarily sealed with a blind flange (flat metal disc). Because the work could not be completed by 6:00 p.m., the blind flange remained in place. The on-duty engineer filled out a permit which stated that Pump A was not ready and must not be switched on under any circumstances.

6:00 p.m. The day shift ended, and the night shift started with 62 men running Piper Alpha. As he found the on-duty custodian busy, the engineer neglected to inform him of the condition of Pump A. Instead he placed the permit in the control centre and left. This permit disappeared and was not found. Coincidentally there was another permit issued for the general overhaul of Pump A that had not yet begun.

7:00 p.m. Like many other offshore platforms, Piper Alpha had an automatic fire-fighting system, driven by both diesel and electric pumps (the latter were disabled by the initial explosions). The diesel pumps were designed to suck in large amounts of sea water for fire fighting; the pumps had an automatic control to start them in case of fire. However, the fire-fighting system was under manual control on the evening of 6 July: Piper Alpha procedures required manual control of the pumps whenever divers were in the water (as they were for approximately 12 hours a day during summer) regardless of their location, to prevent divers from being sucked in with the sea water (fire pumps on other platforms were switched to manual control only if the divers were close to the inlet).

9:45 p.m. Condensate (natural gas liquids NGL) Pump B stopped suddenly and could not be restarted. As the entire power supply of the offshore construction work depended on this pump, the manager had only a few minutes to bring the pump back online, otherwise the power supply would fail completely. A search was made through the documents to determine whether Condensate Pump A could be started.

9:52 p.m. The permit for the overhaul was found, but not the other permit stating that the pump must not be started under any circumstances due to the missing safety valve. The valve was in a different location from the pump and therefore the permits were stored in different boxes, as they were sorted by location. None of those present was aware that a vital part of the machine had been removed. The manager assumed from the existing documents that it would be safe to start Pump A. The missing valve was not noticed by anyone, particularly as the metal disc replacing the safety valve was several metres above ground level and obscured by machinery.

9:55 p.m. 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.[9]

Gas audibly leaked out at high pressure, drawing the attention of several men and triggering six gas alarms including the high level gas alarm, but before anyone could act, the gas ignited and exploded, blowing through the firewall made up of 2.5 x 1.5 metre panels bolted together, which were not designed to withstand explosions. The custodian pressed the emergency stop button, closing huge valves in the sea lines and ceasing all oil and gas production.

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.

10:04 p.m. The control room was abandoned. 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.

Emergency procedures instructed personnel to make their way to lifeboat stations, but the fire prevented them from doing so. Instead the men moved to the fireproofed accommodation block beneath the helicopter deck to await further instructions. Wind, fire and smoke prevented helicopter landings and no further instructions were given, with smoke beginning to penetrate the personnel block.

As the crisis mounted, two men donned protective gear in an attempt to reach the diesel pumping machinery below decks and activate the firefighting system. They were never seen again.

The fire would have burnt out were it not being fed with oil from both Tartan and the Claymore platforms, the resulting back pressure forcing fresh fuel out of ruptured pipework on Piper, directly into the heart of the fire. The Claymore continued pumping until the second explosion because the manager had no permission from the Occidental control centre to shut down. Also, the connecting pipeline to Tartan continued to pump, as its manager had been directed by his superior. The reason for this procedure was the exorbitant cost of such a shut down. It would have taken several days to restart production after a stop, with substantial financial consequences.

Gas lines of 140 to 146 cm in diameter ran to Piper Alpha. Two years earlier Occidental management ordered a study, the results of which warned of the dangers of these gas lines. Due to their length and diameter it would have taken several hours to reduce their pressure, so that it would not have been possible to fight a fire fuelled by them. Although the management admitted how devastating a gas explosion would be, Claymore and Tartan were not switched off with the first emergency call.

10:20 p.m. Tartan's gas line (pressurised to 120 Atmospheres) melted and burst, releasing 15-30 tonnes of gas every second, which immediately ignited. A massive fireball 150 metres in diameter engulfed Piper Alpha, killing two crewmen on a fast rescue boat launched from the standby vessel Sandhaven and the six Piper Alpha crewmen they had rescued from the water.[4] From that moment on, the platform's destruction was assured.

10:30 p.m. The Tharos, a large semi-submersible fire fighting, rescue and accommodation vessel, drew alongside Piper Alpha. The Tharos used its water cannons where it could, but it was restricted, because the cannons were so powerful they would injure or kill anyone hit by the water.

10:50 p.m. The second gas line ruptured, spilling millions of litres of gas into the conflagration. Huge flames shot over 300 ft (90 m) in the air. The Tharos was driven off by the fearsome heat, which began to melt the surrounding machinery and steelwork. It was only after this second explosion that the Claymore stopped pumping oil. Personnel still left alive were either desperately sheltering in the scorched, smoke-filled accommodation block or leaping from the deck some 200 ft (60 m) into the North Sea.

11:20 p.m. The pipeline connecting Piper Alpha to the Claymore Platform burst.

11:50 p.m. The generation and utilities Module (D), which included the fireproofed accommodation block, slipped into the sea. The largest part of the platform followed it.

12:45 a.m., 7 July The entire platform had gone. Module (A) was all that remained of Piper Alpha.

At the time of the disaster 224 people were on the platform; 165 died and 59 survived.[10] Two men from the Standby Vessel Sandhaven were also killed.

Aftermath

There is controversy about whether there was sufficient time for more effective emergency evacuation. The main problem was that most of the personnel who had the authority to order evacuation had been killed when the first explosion destroyed the control room. This was a consequence of the platform design, including the absence of blast walls. Another contributing factor was that the nearby connected platforms Tartan and Claymore continued to pump gas and oil to Piper Alpha until its pipeline ruptured in the heat in the second explosion. Their operations crews did not believe they had authority to shut off production, even though they could see that Piper Alpha was burning.[11]

The nearby diving support vessel Lowland Cavalier reported the initial explosion just before 22:00, and the second explosion occurred twenty two minutes later. By the time civil and military rescue helicopters reached the scene, flames over one hundred metres in height and visible as far as one hundred km (120 km from the Maersk Highlander) away prevented safe approach. Tharos, a specialist firefighting vessel, was able to approach the platform, but could not prevent the rupture of the Tartan pipeline, about two hours after the start of the disaster, and it was forced to retreat due to the intensity of the fire. Two crewmen from the standby vessel MV Sandhaven Fast Rescue Craft were killed when an explosion on the platform destroyed their Fast Rescue Craft; the survivor Ian Letham later received the George Medal. The largest number of survivors (37 out of 59) were recovered by the Fast Rescue Craft MV Silver Pit; coxswain James Clark later received the George Medal. Others awarded the George Medal were Charles Haffey from Methil, Andrew Kiloh from Aberdeen, and James McNeill from Oban.

The blazing remains of the platform were eventually extinguished three weeks later by a team led by famed firefighter Red Adair, despite reported conditions of 80 mph (130 km/h) winds and 70-foot (20 m) waves.[12]

The part of the platform which contained the galley where about 100 victims had taken refuge was recovered in late 1988 from the sea bed, and the bodies of 87 men were found inside [4].

Legacy of accident

Memorial to the disaster in Hazlehead Park, Aberdeen.

The Cullen Inquiry was set up in November 1988 to establish the cause of the disaster. In November 1990, it concluded that the initial condensate leak was the result of maintenance work being carried out simultaneously on a pump and related safety valve. The enquiry was critical of Piper Alpha's operator, Occidental, which was found guilty of having inadequate maintenance and safety procedures. But no criminal charges were ever brought against it.[4]

The second phase of the enquiry made 106 recommendations for changes to North Sea safety procedures, all of which were accepted by industry.[13] Most significant of these recommendations was that the responsibility for enforcing safety in the North Sea should be moved from the Department of Energy to the Health and Safety Executive, as having both production and safety overseen by the same agency was a conflict of interest.[14]

The disaster led to insurance claims of around US$ 1.4 billion, making it at that time the largest insured man-made catastrophe. The insurance and reinsurance claims process revealed serious weaknesses in the way insurers at Lloyd's of London and elsewhere kept track of their potential exposures, and led to their procedures being reformed.[15]

Survivors and relatives of those who died went on to form the Piper Alpha Families and Survivors Association, which campaigns on North Sea safety issues.[16]

The wreck buoy marking the remains of the Piper is approximately 120 metres from the south-east corner of the replacement Piper Bravo platform. A lasting effect of the Piper Alpha disaster was the establishment of Britain's first "post-Margaret Thatcher" trade union, the Offshore Industry Liaison Committee.

A memorial sculpture, showing three oil workers, can be found in the Rose Garden within Hazlehead Park in Aberdeen.[17] The sculptor is Sue Jane Taylor, the Scottish artist who had visited the Piper platform the previous year, and based much of her work around what she saw in and around the oil industry.

In 2008, to mark the 20th anniversary of the disaster, a stage play, Lest We Forget was commissioned by Aberdeen Performing Arts and written by playwright Mike Gibb . It was performed in Aberdeen, Scotland in the week leading up to the anniversary with the final performance on 6 July 2008, twenty years to the day.[18]

Beginning in 1998, one month after the tenth anniversary, Professor David Alexander, director of the Aberdeen Centre for Trauma Research at Robert Gordon University carried out a study into the long-term psychological and social effects of Piper Alpha. He managed to find thirty-six survivors who agreed to give interviews or complete questionnaires. Almost all of this group reported psychological problems. More than 70% of those interviewed reported psychological and behavioral symptoms of post traumatic stress disorder. Twenty-eight said they had difficulty in finding employment following the disaster; it appears that some offshore employers regarded Piper Alpha survivors as Jonahs – bringers of bad luck, who would not be welcome on other rigs and platforms. The family members of the dead and survived victims also reported various psychological and social problems. Alexander also wrote that "some of these lads are stronger than before Piper. They've learned things about themselves, changed their values, some relationships became stronger. People realised they have strengths they didn't know they had. There was a lot of heroism took place." [4]

See also

References

  1. OPCAL’s share 36.5%, Texaco’s share 23.5%, Union Texas Petroleum’s share 20%, and Thomson’s share 20%. CAPLAN, section 1.2
  2. by the end of 1976 and Claymore by the end of 1977, CAPLAN 1.2
  3. http://flickr.com/photos/84214100@N00/2643251484/
  4. 4.0 4.1 4.2 4.3 4.4 Peter Ross (15 June 2008). "The night the sea caught fire: Remembering Piper Alpha". http://scotlandonsunday.scotsman.com/spectrum/The-night-the-sea-caught.4184800.jp. Retrieved 3 June 2010.
  5. Steven Duff (2008-06-06). "Remembering Piper Alpha disaster". BBC News. http://news.bbc.co.uk/1/hi/scotland/7438774.stm. Retrieved 2009-07-25.
  6. http://www.dbd-data.co.uk/bb1998/append11.htm pipeline dimensions
  7. were not designed as blast protection walls and their function was to localise fire CAPLAN 2.6.1
  8. http://news.bbc.co.uk/1/hi/uk/215866.stm Piper Alpha pair 'wrongly blamed'
  9. leakage of condensate from a blind flange assembly at the site of a pressure safety valve CAPLAN volume 2 chapter 5 Causation 1
  10. Hull AM, Alexander DA, and Klein S. Survivors of the Piper Alpha oil platform disaster: long-term follow-up study. The British Journal of Psychiatry (2002) 181: 433-438.
  11. http://home.versatel.nl/the_sims/rig/pipera.htm Piper Alpha
  12. BBC news
  13. http://www.timesonline.co.uk/tol/news/uk/scotland/article4272717.ece Twenty years on, Piper Alpha survivor tells of fleeing fireball
  14. http://media.newscientist.com/article/mg12817431.100-piper-alpha-rewrites-the-rules-on-offshore-safety-.html Piper Alpha rewrites the rules on offshore safety
  15. http://www.lloyds.com/News-and-Insight/News-and-Features/Archive/2008/07/Twenty_years_on_Piper_Alphas_legacy_23072008
  16. http://news.bbc.co.uk/1/hi/scotland/north_east/7483428.stm Widows hope deaths not in vain
  17. http://www.timesonline.co.uk/tol/news/uk/article4282147.ece Piper Alpha North Sea oil rig disaster remembered 20 years on
  18. http://www.hamepages.com/theatre_works_lest_we_forget.html Lest We Forget

External links

Coordinates: 58°27′35″N 0°15′04″E / 58.45972°N 0.25111°E / 58.45972; 0.25111{{#coordinates:58|27|35|N|0|15|04|E|type:landmark_scale:5000000 |primary |name= }}de:Piper Alpha es:Piper Alpha fr:Piper Alpha it:Piper Alpha ms:Piper Alpha nl:Piper Alpha ja:パイパー・アルファ no:Piper Alpha pt:Piper Alpha ru:Piper Alpha sv:Piper Alpha