The Piper Oil Field Engineering Essay
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On the night of June the 6th, 1988, an explosion took place on the Piper Alpha oil and gas production platform. It led to a series of fires that eventually melted the platform into the waters of the North Sea, killing a hundred and sixty seven men, and resulting in insurance losses of U.S. $3.4 billion. To date, it remains the worst offshore disaster in the history of the Petroleum industry, defined in terms of both human and financial loss. The images of horror broadcasted from the disaster site, the final tally of human lives lost, and the enormous financial loss shock Occidental Petroleum, the operator of the platform, violently. It has since become worthy of thorough examination, to fully assimilate the numerous lessons it has to offer. Ronin Advanced Systems investigated the events leading up to that night, pinpointing the deficiencies in the fragile Safety Matrix then applied by Occidental Petroleum, in order to provide viable recommendations that can help prevent such accidents from happening in the future and increase the overall Operational Safety of offshore installations.
Purpose and Scope
The impact of the Piper Alpha disaster on the Petroleum industry was huge. It was on such an unprecedented level that every oil company made it an absolute requirement to document it as a Case Study. The purpose of this research is to isolate the faults and errors carried out by both the management of Occidental Petroleum as well as the crew of Piper Alpha, which directly resulted in the disaster. This report will cover several topics regarding the Piper Alpha offshore production platform, including its location, construction, modification, Safety Matrix and Record, as well as the timeline of the disaster and its aftermath. Throughout the report, we do not include any on-site research from the Piper oil field.
Our recommendations are based on the assumption that the Piper Alpha disaster could have been completely avoided. This is in turn based on the fact that its management made a series of wrong decisions, which seriously compromised the safety level on board the platform and rendered its crew helpless in face of accidents. The failure of the crew to act appropriately with respect to the sequence of events of the disaster can only be attributed to the failure of Occidental's management.
The assumption is also based on the factual and documented deterioration of the safety level on board the platform after its modification to produce gas. Several gas leaks were recorded and a research commissioned by Occidental to investigate the newly installed Gas Lines - which found them of extreme risk - was ignored. At the end of this report, we will prove without a shred of doubt that the assumption holds; thus, deeming our recommendation worthy of being put into action as soon as possible.
The information in this report was compiled from various sources including Lord Cullen's Public Inquiry, numerous printed and electronic publications, video footage from the British Royal Air Force helicopters, as well as the numerous support vessels, that were present on site during rescue operations and the accounts of the survivors.
As mentioned earlier, this research is limited to materials and information available in the Public Domain via the Internet, various publications, and recorded video footage. In addition, Ronin Advanced Systems was not able to send any personnel to the disaster site to perform on-location examination due to the following main reasons:
The incident happened on July the 6th, 1988.
The Piper Alpha offshore production platform melted down to its core. Furthermore, its remains were later detonated and removed by Occidental Petroleum.
Piper oil field
A hundred and twenty miles from Aberdeen, beneath some of the fiercest waters of the North Sea, lies the Piper oilfield. A joint venture of four companies, known as the OPCAL (short for Occidental Petroleum - Caledonia) and led by Occidental Petroleum, obtained a license to explore those waters in 1972, after the British government allowed offshore exploration licenses in 1964 (Miller, 1991). The Piper oil field was discovered in the early months of 1973, prompting OPCAL to commission the construction of the Piper Alpha platform, as well as the pipelines and Onshore Support Installations. Oil production started in late 1976. At its peak, the Piper oilfield produced 30,000 tons of oil daily. Nearby, two more fields were discovered; those were the Tartan and the Claymore oilfields. Two more platforms were commissioned and named after the two fields respectively. The three vast oilfields Piper, Tartan and Claymore are usually referred to collectively as the Piper oilfield.
Figure 1: Location of Piper Oilfield with respect to Aberdeen and Flotta Oil Facility
As shown in Figure 1, OPCAL built the Flotta oil terminal on the Orkney Islands to collect and process oil from the three massive fields. As the development of the three platforms progressed, more oil and gas lines were laid, resulting in Piper being at the heart of a busy network of pipelines. Its platform acted as both a communication systems hub as well as an oil and gas collection point, before relaying it all onto shore on one main line, namely the Main Oil Line or MOL, which is the line seen connecting the Piper field and Flotta in Figure 1. This report will dedicate an entire subsection to further examine the pipeline network surrounding the Piper oilfield and its neighbouring counterparts. It will also discuss the impacts that network had on the level of Operational Safety on board the Piper Alpha platform and how it actively contributed to its tragic and total eradication off the waters of the North Sea.
Piper Alpha, the platform that exploited the Piper oilfield, stood tall at two hundred metres above seabed. Its sheer size made it seem almost indestructible. It was originally designed for oil production, but was later adapted to produce natural gas as well; a decision that proved to have tragic consequences. Producing almost ten percent of Britain's North Sea oil and gas in 1988, Piper Alpha was highly productive. It was deemed a lucrative investment for Occidental Petroleum, shoring millions of dollars annually. It is assumed that at the time of the accident, the platform was the heaviest offshore production rig operating in the North Sea.
Figure 2: Piper Alpha Offshore Oil & Gas Production Platform
Piper Alpha was a fixed platform constructed by McDermott Engineering at Ardesier and UIE at Cherbourg, with sections united at Ardersier during 1975 (Wikipedia, 2010). The platform consisted of four modules (A, B, C and D) separated by Fire-Proofed walls, and arranged such that the most dangerous works - such as drilling - were as far as possible from the Accommodation Block. At the time of the accident, the platform operated thirty-six well heads using various technologies that were then available. Figure 3, an East-side Elevation of the platform, illustrates its modular design and the locations of the areas of interest to the scope of this report, mainly Modules C, D and the Oil Separation Compartment in Module B.
Figure 3: East Elevation of Piper Alpha
the impacts of the 1980 Gas module fitting
Impact on the platform Layout
I - Production Level 84
In 1980, a Gas Recovery Module was installed on the Piper Alpha platform. This decision left an unfortunate legacy in its design, as some of the gas compression works had to be sited in Module C, which was later called the Gas Compression Module. Figure 4 illustrates the layout of Production Level 84. It clearly shows how the compression works in Module C were close to many sensitive areas in Module D, such as: the Control Room, the Electrical Power Gas Turbine Generators, the Emergency Diesel Generator, the Fire Pumps Manual Control Panel and some of the Electrical Switch Rooms. The Accommodation Block, where the crewmen lived, was located above Module D, with the Helicopter Pad (or Helideck) on top of it as shown in Figure 3.
Figure 4: Production Level 84 & Firewalls
Hazard: Blast-Proof Walls
Since Piper Alpha was initially designed to produce oil, only Fire-Proofed walls were installed to separate its four modules instead of Blast-Proof walls, which are installed on gas production platforms. Figure 4 shows the locations of the Fire-Proofed walls as well as their ratings. The B/C and the C/D walls did not withstand the first explosion. Their failure was the beginning of the end for the platform.
Hazard: Fire-Fighting System
Piper Alpha was equipped with a state-of-the-art Automatic Fire-Fighting System. It relied on two different sets of pumps for operation; electrically powered and diesel powered. They would suck in huge amounts of seawater - via underwater inlets - to douse any fires. However, the safety procedures on the platform dictated that the system would be switched over to manual control in case divers were in the water - regardless of their locations with respect to the inlets - so that they would not get sucked in. That procedure never considered the possibility of a fire or an explosion blocking access to the Manual Control Panel, preventing the crew from operating the pumps and eventually causing the fire to rage unchallenged.
ii - deck support frame: level 64
Two large gas pumps, designated A and B, were placed in Module C. Those were responsible for pressurizing the produced gas and sending it to the offshore Manifold Compression platform MCP-01, some thirty miles to the North West of Piper Alpha. They were also responsible for providing the gas required for generating Electrical Power that fed the entire platform. They operated in redundancy; i.e. one was operated and the other was put on standby in case the former stopped working. Those two pumps were present on level 68, sixteen levels below production level number 84.
Figure 5: Deck Support Frame of Level 68 & Location of Pumps A & B
A pipeline eighteen inches in diameter acted as the Main Gas Line (MGL), carrying the gas production of Piper Alpha to the Manifold Compression Platform, MCP-01. A year later, another eighteen-inch pipeline was extended from the Tartan platform to Piper Alpha, in order to collect gas production from both rigs before sending it on the Main Gas Line to MCP-01. Later on, another sixteen-inch pipeline was extended from Piper Alpha to the Claymore production platform, to feed its onboard Gas Lift System.
Hazard: Gas Lines
In Figure 5, all gas lines - also known as risers - were secured with automatic Emergency Safety Valves (ESVs) and Pig Traps to cut off gas flow in an out of the platform in case of emergencies and failures. However, there were no Remotely Operated Shutoff Valves (ROSOVs) on any of the lines that the neighbouring platforms could use in case the ESVs had failed or in case things on Piper Alpha had gone out of control. Moreover, two years prior to June the 6th 1988, Occidental Petroleum commissioned a report to investigate the safety of the platform after the added functionality and pipelines. The report portrayed a fearful image, clearly warning of the dangers of the gas lines. The findings stated that those gas lines would take hours to depressurize, mainly due to their capacities that was defined based on their lengths and diameters. The report went on to speculate that should anything happen to those lines, they could result in a High-Pressure Gas Fire that would be virtually impossible to fight. Thus, putting the entire platform at risk, and threatening the lives of its personnel.
Impact on the Pipeline network
Since the Piper oilfield was the first to be discovered, and Piper Alpha was the first platform to come online, its historic development and that of adjacent fields meant that the platform would become a centre for communication systems, as well as oil transfer, reaching land-based operations (Drysdale & Evans, 1998). The belated installation of the Gas Module, and the subsequent extension of Gas Lines, further complicated an already complex network of pipelines interconnecting the three platforms Claymore, Piper Alpha, and Tartan with one another as well as with MCP-01 and the Flotta oil processing facility.
Figure 6 shows this complex network of oil and Gas Lines connecting the four platforms and onshore installations. The Main Oil Line (MOL) carried oil from Piper to Flotta. Oil was routed from Tartan to Claymore, via a separate line, and from there it was sent onto the MOL, some thirty-five miles west of Piper. The MOL also carried the main communication cable (originating at Piper Alpha) between the three rigs and Occidental's Control Centre (OCC) on the Orkney Islands.
Hazard: Oil Back Pressure
The legacy of that design had not only reduced the level of Operational Safety on board of Piper Alpha significantly, but also it had put the entire communication system at risk. The design simply jeopardized losing all cable-based communications with OCC, in case an explosion or a massive rig fire took place. Furthermore, due to the lack of any Remotely Operated Shutoff Valves (ROSOVs) - which would prevent the back flow of oil because of pressure differences and/or major failures in the Emergency Safety Valves (ESVs) - the design exhibited a Back-Pressure nature that would allow oil from the Tartan and Claymore platforms to flow directly back into Piper Alpha - instead of going down the Main Oil Line to shore - should Piper Alpha stop pumping oil. That hazard was an important factor in fuelling the oil fire that started in the Oil Separation compartment in Module B on board of the platform in peril.
Figure 6: Claymore, Piper, & Tartan Pipeline Network
spiral to disaster
The common image of the disaster can be attributed to a single devastating explosion on board the Piper Alpha. In fact, once it took place, the catastrophe unfolded gradually. During one crucial hour, there were critical moments that it could have been averted. However, an unfortunate series of events led to the total destruction of the platform.
On the morning of July the 6th, Pump A was undergoing routine maintenance and its pressure valve was removed for inspection. Another maintenance overhaul, which would have taken two weeks, was scheduled for the same pump but had not begun then. The valve removed was placed between the pump and the gas pipe feeding it. The service crew sealed the pipe with a Blind Flange; a flat metallic disc used to temporarily cover pipes and risers during various routine maintenance jobs. When the Day Shift ended at 6:00 PM, the job was not done. The supervising engineer prepared a Permit-to-Work (PTW) stating that the pressure valve was removed and that the pump should not be started under any circumstance (Wikipedia, 2010).
The engineer then headed to the Control Room, where he found the platform's manager busy. He chose not to inform him that Pump A was out of order, and instead signed the new PTW, placed it on the manager's desk and left to the Accommodation Block. This was the first critical moment in the timeline of the accident. The failure of the engineer to inform the manager with the serious condition of the pump is nothing but a clear example of terrible lack of communication between colleagues. It showcases a superficial attitude and approach by Occidental's personnel towards Safety. This failure is one of the main reasons of the disaster, if not its main trigger.
An hour later, another maintenance job was taking place underwater; divers were carrying out a routine inspection and welding job on one of the pipes. Therefore, and as we explained previously, the Automatic Fire-Fighting System was switched to manual control. This was a safety practice to ensure that divers would not get sucked in through the underwater inlets of the powerful fire extinguishing pumps. It is worth noting that on other platforms Fire-Fighting systems were controlled manually only if divers were very close to the inlets. This practice, which was enforced to ensure the safety of the divers, reduced that of the platform drastically and deprived it from an automated response by the Fire-Fighting System that could have saved it from its fatal doom; yet another critical moment down the course of the horrible disaster.
At 9:45 PM, Pump B suddenly stopped and could not be restarted. The pumps were responsible for providing gas to the Gas Turbine Generators, which in turn provided the entire platform with Electrical Power. The sudden stop of Pump B, and the failure to restart it, threatened the total loss of Electrical Power during ongoing drilling operations. This meant that the drilling head could get stuck at enormous costs. The system provided fifteen minutes of backup power, via the Emergency Diesel Generator, during which the only two choices were either restarting Pump B or bringing Pump A online; a crossroads that sent the platform and its crewmen down the spiral to disaster.
Pressured as time went by with no success at restarting Pump B, the engineer who was sent down to inspect the pump was forced to consider bringing Pump A online. He returned to the Control Room on level 84 and searched through the PTWs, trying to determine whether Pump A could be started or not. He located the PTW for the General Overhaul that had not started then, yet failed to find the newer one that stated that the pump's pressure valve was removed. He signed off the General Overhaul PTW and returned to level 68 to start Pump A.
The reason why the engineer could not find the newer PTW is simple; the pressure valve was in a different location from the pump and therefore its permits were stored in a different box, as PTWs on board the platform were sorted by location. The engineer never checked the PTW box for the location where the pressure valve was. None of the personnel present in the Control Room then was aware that a vital piece of the pump had been removed. The platform's manager assumed from the existing documents that it would be safe to start Pump A (Wikipedia, 2010).
In fact, no one noticed that the pressure valve had been removed as it was placed several metres above the ground of level 64. Furthermore, it was blocked from line-of-sight by gas risers. Ten minutes later, Pump A was started, allowing gas to flow into it in the absence of the pressure valve, which quickly resulted in an overpressure the Blind Flange could not withstand. Gas started to leak at very high pressure and in great amounts, with audible sounds that took the crewmen on level 64 by surprise. The leak triggered several gas alarms. However, at exactly 9:50 PM, and before anyone could realize the situation and plan a response, the gas ignited and exploded, blowing through the Fire-Proofed walls.
In the initial blast, the Fire-Proofed walls B/C and C/D failed. Panels from the C/D wall were propelled into Module D, destroying the Control Room, the Emergency Diesel Generator, and the Gas Turbine Generators, starting a hydrocarbon fire - fed by a mixture of gas and diesel - and blocking access to both the Manual Control Panel of the Fire-Fighting System as well as the Lifeboat Entry Points. The platform's manager quickly pressed the Emergency Shutdown button, closing the Emergency Safety Valves (ESVs) on the sea lines and ceasing all oil and gas production, before ordering an evacuation of the Control Room. This should have isolated the platform entirely from the flow of oil and gas. However, Panels from the failing B/C Fire-Proofed wall flew into Module B, rupturing another gas pipe as well as the main oil separation manifolds, starting an oil fire in the Oil Separation compartment, which spread out to all of Module B within a few minutes.
Figure 7: The Initial Fire on Piper Alpha. Black smoke - indicating an Oil Fire - is seen rising from Module B
The manager headed to the Radio Room, where he ordered a Mayday call to be transmitted. The Radio Room was then evacuated and all personnel headed to the Fire-Proofed Accommodation Block awaiting further instructions or evacuation by helicopters.
Although Occidental's management was aware that a gas explosion on board Piper Alpha would be devastating, the managers on Claymore and Tartan never Shutdown oil production after they received the Mayday transmitted out of the burning platform. Even though black smoke could be seen on the horizon, which meant that there was an oil fire, the managers never suspected the failure of the Emergency Safety Valves (ESVs). The oil fire, fed by oil from Tartan and Claymore, heated up the Tartan Gas Line to the point it failed. The pipeline ruptured, releasing 15~30 tonnes of gas (pressurised to 120 ATM) per second. The gas burst into a massive fire ball that engulfed the entire Piper Alpha platform as well as a Fast Rescue Craft launched from the Multi-purpose Vessel Sandhaven. This situation was exactly what the report commissioned two years earlier had warned against; a High-Pressure Gas Fire that would be impossible to put out. At this critical moment, the fate of the platform had already been decided, with no viable means of reversing it. The massive fire ball can be seen in Figure 8, as it instantaneously contained the platform and darkened the clear blue sky above it.
Figure 8: Sequence of Images taken from a Video Footage captured by a Support Vessel showing the Explosion of the Tartan Gas Line. MV - Lowland Cavalier can be seen on the Right
As Figure 8 vividly illustrates, the wind was blowing in the direction of the Helideck, which in turn pushed fire and smoke towards it, making any helicopter landing absolutely impossible and an act of suicide. No further instructions were given to the trapped crewmen, who took shelter in the Accommodation Block, while smoke began to penetrate it. Some were seen jumping off the platform and into the water, against what their training instructed. Ironically, those were the ones who survived the tragic ordeal. The actions of two crewmen are worth noting. As the situation worsened, they donned Personal Protective Equipment (PPE) and tried to make their way to the Manual Control Panel of the Fire-Fighting System to start the diesel pumps. Those two men were never seen again and their bodies were never recovered.
Nearby, and as the situation rapidly escalated, the managers on Claymore and Tartan believed that they did not have the authority to order an Emergency Shutdown of production without first consulting their superiors. The initial explosion knocked off the main communication line with OCC; however, Tartan's manager somehow contacted his superior, and was instructed to stay online and continue pumping gas and oil. Meanwhile, Claymore's manager tried for more than twenty minutes to raise OCC by satellite phone, but to no avail. When he finally succeeded at contacting his manger, the MCP - 01 Gas Line failed and exploded, as they were speaking, at exactly 10:50 PM. It was not until that point that Claymore's manager finally ordered an Emergency Shutdown of production, after receiving instructions from his superior, who also instructed him to contact Tartan and tell them to shutdown as well.
Figure 9: Sequence of Images taken from a Video Footage captured by a Rescue Helicopter showing the Explosion of the MCP - 01 Gas Line. The MSV - Tharos can be seen on the Right
By the time both platforms had ordered an Emergency Shutdown, there was no turning back for Piper Alpha; the platform was destined to burn for hours more to come, until the pipelines were depressurised, and all the hydrocarbons they carried were depleted. The fearsome heat ate its way at the machinery and steelwork comprising the once gigantic platform in a tremendous scene that horrified everyone who saw it.
The final chapter in the disaster was inevitable and quite expectable. The gas line feeding Claymore finally failed and ruptured at 11:20 PM. The third explosion was the final nail in the platform's coffin. After withstanding the intense heat for more than an hour, the Generation and Utilities Module D, home to the Accommodation Block, finally slid into the sea. Most of the platform soon fell after it. Forty-five minutes past midnight, the entire platform was gone, and only Module A was all that remained.
Figure 10: Image from Video Footage taken by a Rescue Helicopter landing on the MSV-Tharos as the Final Explosion of Claymore's Gas Line take place
The Role of nearby Support vessels
The Multi-purpose vessel LowLand Cavalier (mv - lowland cavalier)
Although the Lowland Cavalier was the closest to Piper Alpha at the time of the initial explosion, she was only equipped as a Diving Support vessel then. She pulled away to safety immediately, after signalling the underwater divers to surface. Her role in the disaster was limited to reporting the first explosion.
Figure 11: Recent Photos of the MV - Lowland Cavalier
The Multi-purpose vessel Silver Pit (mv - silver pit)
The Fast Rescue Craft MV - Silver Pit was a converted fishing ship, with a small Landing Area (yellow circular area seen in Figure 9). It was the first support vessel to respond. The largest number of survivors - thirty-seven out of fifty-nine - was recovered by her crew. Her coxswain, James Clark, received the George Medal - a second level civil decoration of the United Kingdom & Commonwealth - in recognition of his tremendous efforts in the Search & Rescue operation (Scottish TV, 2010).
Figure 12: Image taken from a Video taken by a Rescue Helicopter during a Winch-Recovery of a Survivor picked up by the MV - Silver Pit
the Multi-purpose vessel sandhaven (mv - sandhaven)
Though her actions show obvious disregard for common logic and safe practices, the efforts exerted by the crew of the Sandhaven were remarkable; they raced against time to rescue Piper's oilmen from the raging inferno. In an insane act of bravery, and in defiance to every safety rule and procedure known in the world of Offshore Rescue Operations, she approached the burning platform to a very close distance, launching a fast rescue boat - with three men on board - that rescued six of Piper's crewmen. However, when the gas line from Tartan exploded, a massive fire ball engulfed the burning platform as well as that boat, killing two of its crewmen along with all of survivors. The lone survivor on board that boat, Ian Letham, was also awarded the George Medal in recognition of his participation in the relief efforts during the tragic ordeal.
Figure 13: The Tharos (Left Background) & Sandhaven (Small Red Boat) next to Piper Alpha just as Tartan's Gas line exploded
the Multi-purpose Support Vessel Tharos (msv - tharos)
The Tharos was a semi-submersible, multi-purpose support vessel. She comprised several roles such as Fire-Fighting, Construction, Accommodation and Diving Support. She also carried a fully operational hospital and was equipped with a massive Helideck. She was commissioned by Occidental Petroleum precisely to deal with emergencies on offshore platforms. On June the 6th, 1988, and by pure chance, she was anchored close to Piper Alpha. She should have been a Godsend; however, upon approaching the burning platform, her crew started her water cannons too fast, tripping the Fire-Fighting system and wasting ten long minutes before successfully restarting it. Furthermore, those cannons were deemed very powerful, thus restricting the Tharos to as where to use them; since the stream could seriously injure or even kill anyone it hits.
Figure 14: Images taken from Video Footage taken during the landing of a Rescue Helicopter on the Helideck on board the MSV-Tharos showing the Vessel's powerful cannons engaged in Fire-Fighting Operations
Figure 12 shows how close the Tharos was anchored to Piper as well as the locations of the MV -Lowland Cavalier and the MV - Silver Pit mentioned earlier in this section.
Figure 15: Locations of Support Vessels from Piper Alpha
Worse still, the Tharos was equipped with an extensible bridge that could have worked as an escape route for the personnel trapped onboard, but due to flaws in its design it proved useless. The extension mechanism was too slow, taking five minutes to move two feet; so to extend to its full thirty metres, it would have taken over an hour. At 10:50 PM, the Tharos ran out of time; the MCP-01 Gas Line ruptured and burst. A huge fireball burnt brightly in the dark sky over the North Sea, and to date is considered an icon of the Piper Alpha disaster. The gas burning was more than the entire consumption of the United Kingdom. The intense heat threw the Tharos back, forcing her to return the bridge into its storage position, and from then on, her crew could only witness as Piper slowly melted and collapsed (McGinty, 2009).
Figure 16: Screenshot from a Video Footage taken by a Surveillance Camera on board the MSV-Tharos showing the Extensible Bridge being extended towards Piper Alpha
Figure 17: The Tharos docked to Piper Alpha via its Extensible Bridge Weeks before the Disaster
Figure 10 shows the extensible bridge docked to Piper Alpha weeks before the disaster. Had the Tharos attempted to approach Piper to such a close distance, the situation would have turned into a nightmare, and the Tharos would have been engulfed in flames just like the Sandhaven. The Tharos continued fighting the fire from a safe distance until the morning of the following day.
Divers from the Tharos recovered many bodies from the sea bed and from the galley area of the Accommodation Block, where most of the crewmen onboard gathered awaiting extraction by helicopter. The vessel supported the Fire-Fighting and Well Kill operations that eventually led to the extinguishing of the burning well three weeks later (Wikipedia, 2010).
The Day After
With the break of light of the following day, the scale of the disaster was unravelled. The entire platform melted down to its core through the night and sank into the sea. Ironically, Module A, once considered the most dangerous section of the platform, remained fairly intact. That was attributed to the fact that the Fire-Proofed wall separating modules A and B did not fail. Of the massive platform, only what shows in Figures 15 and 16 was what was left.
Figure 18: Module A carrying a sign with the platform's number and name "Piper A"
Figure 19 : The Remains of Piper Alpha with the MSV-Tharos in the Background
A total of a hundred and sixty seven men lost their lives in the disaster; of which, a hundred and sixty five were Piper Alpha crewmen. A hundred and sixty four of them died on site and one died later in hospital. Two crewmen from the MV - Sandhaven died, along with six survivors from the platform, when their fast rescue craft was engulfed in flames after the explosion of Tartan's gas link.
Only sixty one men survived, almost all because they had decided to ignore what little training they had been given and jumped off the burning platform.
The total financial loss amounted to U.S. $3.4 billion. It was paid in full by insurance companies that insured the platform and the personnel against operational hazards. The insurance companies also covered the cost of the Clean-Up operation.
Damage to Public Image
Occidental Petroleum claimed that their Safety Record was impeccable, claiming that it was the first time in twelve years that they had had a causality in the North Sea. However, their statement was challenged when various sources revealed that an oilman died four years earlier on board Piper Alpha. That, coupled with the surfacing of the Risk Assessment Report commissioned two years before the disaster, proved that Occidental's management approached Safety rather superficially. The families of the victims went to court, suing Occidental for negligence. All lawsuits were settled out of court, with Occidental paying large sums to the afflicted families.
The burning remains of the Piper Alpha platform were eventually extinguished three weeks later by a team of experts led by the famous Fire-Fighter Red Adair in bad weather conditions of seventy-foot high waves and a hundred and thirty km/hour wind. A year later, Occidental commissioned a detonation of the remains, sold all of its interests in the North Sea and left Scotland.
The findings of our analysis are quite dramatic. The fragile Safety Matrix, then applied by Occidental, collapsed in less than twenty minutes. When the Tartan gas line exploded, the fate of Piper Alpha was very much decided already, and nothing could have salvaged it. The following are the main members of the Safety Matrix that failed catastrophically.
It was the decision to install a gas recovery module without taking the proper safety precautions into consideration that first compromised the operational safety on board Piper Alpha. Neither the condensate gas pressure pumps were placed in a safe location - far enough from sensitive areas - nor the platform's Fire-Proofed walls were replaced with Blast-Proof ones. The legacy of the design of the platform solely for oil production was a heavy burden that sank it into the North Sea.
The entire network of pipelines was not equipped with any Remotely Operated Shutoff Valves (ROSOVs). Thus, it exhibited a Back-Pressure nature that led to oil and gas flowing back into Piper Alpha even though its manager had activated the Emergency Shutdown switch, ceasing all oil and gas production. That action should have activated all the Emergency Safety Valves (ESVs) on the lines and isolated the platform from hydrocarbons. However, due to the failure of several ESVs, oil and gas were fed straight back to the platform, fuelling the fire to an unprecedented and catastrophic magnitude.
Fire Protection System
Though Piper Alpha was equipped with an automatic Fire-Fighting System, the presence of divers underwater at the time of the accident deprived the platform of yet another chance to escape its doom. Even though the electrical pumps were destroyed in the initial blast, the diesel pumps would have been sufficient to put out the initial fires in modules B and C.
Permit to Work (PTW) System
The Permit-to-Work (PTW) system failed miserably at providing the platform's manager with a clear condition of Pump A. It was the fact that PTWs were stored in separate boxes - according to the locations of their respective machines and parts - that prevented both the manager as well as the second maintenance engineer - who was called to inspect Pump B after its failure - from learning the condition of Pump A accurately.
Onboard Communication System
The design of the platform did not take into the consideration the possibility of the destruction of the Control Room. Right after the initial explosion, the manager had to evacuate the Control Room, and then later on the Radio Room was also abandoned after transmitting a Mayday (derived from the French phrase: "Venez m'aider" or come help me) call. There was no trial whatsoever to use the Loud Speakers system on board the platform to communicate with the crew and instruct them on what to do.
The crew of the Tharos wasted ten precious minutes in restarting the Fire-Fighting System, which they started too fast that it tripped. Furthermore, since the crew of Piper Alpha were not able to abandon the platform (no mass-evacuation whatsoever was attempted; except for the men who acted individually and jumped off the platform into the North Sea) the Tharos was restricted to as where it can aim its High-Pressure water cannons; as the water stream was powerful enough to injure or even kill anyone it might hit. Thus, the Tharos did not operate at its full capacity and Passive Fire-Fighting did not manage to salvage the platform from the burning inferno it became.
Delayed Decision Making
The network of pipelines feeding oil and gas in and out of Piper Alpha had the most catastrophic consequences of all, due to delayed decision making by the neighbouring platforms' managers. The managers could not reach OCC when the initial explosion knocked off the main communication line. They continued pumping oil and gas to the platform and on the Main Oil Line (MOL), fuelling the oil fire in Module B and maintaining pressure on the gas lines (risers). The oil fire heated up the gas lines, which later failed and exploded, resulting in the High-Pressure gas fire the report commissioned two years earlier by Occidental anticipated.
The managers feared the financial consequences of shutting production down, albeit seeing black smoke on the horizon clearly; an indicator of oil fire and the failure of the Emergency Safety Valves (ESVs). It would take days for a platform to come back online, and more to reach normal production level. Had the managers been empowered to make such decisions without fearing the consequences, the fate of Piper Alpha could have been averted or at least delayed.
In order to prevent such accidents from happening in the future, and ensure the safety of the personnel operating on offshore installations, several precautions are to be taken, of which we recommend applying the following as soon as possible:
Changing the Permit-to-Work (PTW) system. The Permit-to-Work system based on locations of machinery proved to be a failure. Hence, a PTW system based on the machinery itself, and all parts that are possibly related to it, is found to be much safer and is strongly advised.
Installing Blast-Proofed walls. The Fire-Proofed walls did not withstand the initial blast, which could have been contained if Blast-Proofed walls had been installed. That would have prevented the fire from spreading all over the platform and gave the personnel a better chance of handling the situation. Hence, installation of Blast-Proofed walls is advised on all offshore installations.
Securing Accommodation Blocks against Smoke. The majority of bodies recovered from the Accommodation Block of Piper Alpha died of smoke and gas suffocation. Therefore, all Accommodation Blocks should be secured against smoke, and provided with excellent ventilation to ensure the safety of its occupants until they can be evacuated safely.
Moving Lifeboat Entry Points to Accommodation Blocks. The fire on Piper Alpha prevented the crew from reaching the Lifeboat Entry Points, but not from reaching the Accommodation Block. Had the Lifeboat Entry Points been there, the trapped men could have escaped to safety. It is thus obvious that those points need to be moved to Accommodations Blocks, the farthest module from all dangerous zones.
Installing Remotely Operated Shutoff Valves (ROSOVs). The lack of Remotely Operated Shutoff Valves, combined with the failure in several Emergency Safety Valves (ESVs) provided the initial fires on Piper Alpha with the fuel they required. ROSOVs would have helped the managers of neighbouring platforms - Claymore & Tartan - secure the Main Oil Line (MOL) and prevent back-pressure from feeding oil back in the burning platform. It is thus recommended to install Remotely Operated Shutoff Valves on every stage and intersection of oil and gas pipeline.
Empowering platform Managers to Make Critical Decisions. The managers of the Claymore and Tartan production platforms believed they were not entitled to shutdown production on both rigs, albeit seeing the burning platform on the horizon. In fear of managerial and financial consequences, the managers instead tried to contact their superiors, wasting valuable time in the process, to seek advice. Had they been authorized to make such a decision without being in fear of further consequences, the managers of both platforms could have helped avert a disaster. Thus, it is crucial to empower platform managers to make critical decision during emergency situations.
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