By Captain Chandra Godakanda Arachchi

Master Mariner, Gladstone LNG Australia

S. S. Titanic was said to be unsinkable. Similarly the oil platform, Piper Alpha, owned by Occidental Petroleum, 110 miles from the Port of Aberdeen, operated in extreme weather conditions for most part of the year and, therefore, was considered indestructible. The sheer size of the structure also contributed to this view. The sinking of Titanic has been the maritime disaster of all time and the Piper Alpha disaster where 70 percent of the 226-member crew on board, in the North Sea, is said to be the worst off-shore oil platform tragedy of all time. A series of explosions caused some sections of 300-foot tall structure to collapse within three hours. It became a flaming ball of twisted metal.

Piper Alpha was producing 30,000 tonnes of oil per day, 10 percent of the British North Sea oil production. The shipping industry witnessed an unprecedented regulatory regime post the grounding of Exxon Valdez, in Alaska, in 1989, causing a massive crude oil spill; similarly Piper Alpha disaster led to the introduction of significant regulatory changes in the oil and gas industry in terms of safety improvement and managing “Permit to work” system.

Piper Alpha, which operated 12 years from 1976, was first built for oil production but modified for gas production as well. Piper Alpha was connected to a network of oil platforms (Claymore and Tartan).

Almost all survivors from Piper Alpha were those who jumped into the burning sea from a height about three hundred feet which required a lot of courage.

What really happed on 06th July 1988. Here is the story in brief!

It was just another summer night in North Sea, 06 July, 1988. Some 226 crew on board Piper Alpha were having another night shift with usual problems the control room had to deal with.

Piper Alpha had two gas pumps (centrifugal compressors), A & B, to boost gas pressure for delivering gas to Flotta, an island terminal off Scotland. There had been two work permits issued during the day shift, one for pressure safety valve (PSV) servicing and the other for overhauling compressor A; the work would have taken two weeks. The crew had removed the PSV for servicing and taken compressor A out of service only by isolating power, which is illegal. The industry now requires full isolation, key common lockout by workers, permit holder and permit authority so that everyone involved in work has to unlock before being able to start the compressor. Crew could not complete servicing PSV as expected by 1800 hrs and the engineers decided to postpone reinstating the PSV until morning and fitted a blind flange (metal plate) where the PSV had been removed. (It was probably not a pressure rated flange). The overhauling of the compressor A had not begun during the day shift, and this was noted in the work permit form. When the engineer concerned arrived in the control room to hand over the permits, the supervisor was busy and therefore he failed to inform the latter that the PSV was out of service. He, however, made notes on the permit form, returned two permits and knocked off for the day. Unfortunately, two permits got separated in the control room. There could have been many permits on that day due to a new gas line being installed during weeks. Piper Alpha was not shut down for gas line installation as the installation could be managed with control measures as stipulated. A critical aspect to note here is that nobody in the control room had an update of incomplete PSV work. In the mean time, the diesel fire-fighting pumps had been switched to ‘manual from ‘auto’ as a control measure to prevent divers who were at work being sucked in case the fire pumps started in ‘auto’ mode.

At 2145 hrs, the compressor B tripped and failed to restart despite repeated attempts by the control room. Now, there was another risk looming due to tripping the compressor. In case of failure to get the compressor started within a certain period of time, the platform runs the risk of losing gas pressure, which is required to run the gas generator. The consequence of shutting down the gas generator is huge with platform shutting down including drilling. There is also the likelihood of the drill head getting stuck. Getting everything back online is a time consuming and that involves a huge cost. Therefore with this scenario in mind, the shift engineer traced the permit for compressor A and noticed that overhaul work had not begun but failed to realise PSV was out of service due to the unfortunate separation of permits. At 2155 hrs, the supervisor assumed it was safe to start the compressor A and ordered reinstating power and got it online. As the PSV was located about five metres above the compressor, the crew failed to notice the missing PSV. As the compressor started at 2157 hrs due to the sudden rise in pressure, gas started to leak from the temporary blind flange. A huge amount of gas leaked and alarms were going off in the control room continuously; this was followed by an explosion. The supervisor immediately activated the emergency shutdown (ESD), which shut off safety valves (XVs) of the huge oil and gas production risers of Piper Alpha from sea bed, isolating Piper Alpha, but it appears that it did not shut down the connections to other network oil platforms. The explosion did rupture the fire walls in oil separator area, which caused an oil fire to erupt.

It was believed that at 2204 hrs only two crew members had been killed due to the blast. There had been similar fires in certain other rigs but they had been doused. When the fire started, fire fighting pumps should have started, but unfortunately pumps had been switched to ‘manual’ as was said previously. Two brave members tried to and start the pumps manually, but they failed and were never seen again. At this stage, emergency procedures simply collapsed and the Rig Manager who was supposed to coordinate the emergency from radio room sent a distress message, which was heard by the two nearby rigs, Claymore and Tartan. No attempt was made to announce the distress message over the public address system. No one told the crew what to do. Workers were supposed to gather at life boat deck and wait for instructions in case of emergency, but the fire prevented them from reaching the muster point and, therefore over 100 crew members waited in fireproof accommodation block beneath the helicopter pad and waited for helicopter rescue. However, the wind was blowing the heavy smoke over the helicopter pad and it was impossible for the helicopter to land. Accommodation block too gradually started to fill with smoke and even at this there was no attempt whatsoever to evacuate the crew to safety.

ESD had shut down oil and gas production, but oil in the separator continued to burn, and it eventually burnt itself out with the fire extinguishing itself, but Claymore continued to pump oil even though Claymore heard the May Day, and witnessed the flames of Piper Alpha from a distance. It was waiting instruction from on shore Occidental control room to shut down. Claymore repeatedly attempted to contact the shore control room for a long time but without success. Therefore the discharge pressure of Claymore and Tartan oil pumping fed oil through a damaged pipework to fire on Piper Alpha, adding more and more fuel to fire. Both Claymore and Tartan knew it was costly to restart the production from platform post ESD, and that perhaps led them to wait for instructions to shut down rather than taking decisions on their own.

There was another huge problem looming at 2218 hrs with oil fire heating the high pressure gas risers (on Piper Alpha) from Titan. Heat eventually damaged the pipe work of high pressure gas riser from Tartan, adding three tonnes of gas per second to already burning Piper Alpha. Most crew members were still alive. Some of them decided to jump into the burning sea from a ten-storey-high Piper Alpha prior to the second explosion. Those are the people who survived and 167 crew members were killed. More than 75% of the Piper Alpha facility was destroyed although it had been considered indestructible. Emergency response vessel Faros by luck happened to be there anchored closer to Piper Alpha. It attempted to start the fire pumps in a hurry, causing them to trip and this led to a 10-minute delay in operating them. The extendable gangway was unusually extremely slow and it took more than an hour to reach the deck with crew. It was too late. After the second explosion, Faros could not get closer to Piper Alpha due to intense heat and it manoeuvred away from Piper Alpha for its own safety.

Occidental Petroleum later destroyed the remains of Piper Alpha within a year, closed down the operation never to operate in the North Sea ever again. Investigators found that the safety culture on Piper Alpha had been superficial. CEO of Occidental Petroleum at a post-disaster press conference said that 06 July 06 was the first incident in twelve years since the commencement of operations, but the fact remains that a crew member had been killed in an accident four year prior to the Piper Alpha tragedy. That could have been an ideal opportunity for the company to review safety procedures on Piper Alpha. Had Occidental Petroleum been seriously committed to safety, the incident probably would not have occurred and 167 crew would not have been killed.

It is extremely important to comply with safety standards in oil and gas industry.

(The writer has nearly 25 years of experience in oil and gas industry in Australia)