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Facing offshore dangers
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With a total of 167 fatalities and only 62 ºsurvivals, the Piper Alpha fire became the world’s worst-ever offshore oil disaster. Most of the victims suffocated in toxic fumes, which developed after a gas leak set off the blasts and sparked the fire.
The fire broke out on the evening of 6 July 1998. Pilots reported seeing an “inferno” up to 350ft (107m) high and a platform wrenched apart. A leakage of natural gas condensate, which had built up beneath the platform ignited, causing a massive explosion. The explosion ignited secondary oil fires, melting the riser of an upstream gas pipeline. The released gas caused a second, larger explosion which engulfed the entire platform. Approximately 225 men were working on the rig owned by Occidental Oil.
“What happened in the Piper Alpha is that many of the people who survived are the people who actually broke the rules,” said Perry. Under the established rules, personnel go to the accommodation module for safety in this kind of emergency.
“Most of those rescued said they survived by sliding down pipes or jumping hundreds of feet into the sea which was covered in burning oil.”
The immediate cause of the gas escape was the putting into service of a condensate pump, downstream from where a pressure relief valve had been removed for maintenance, Perry said. Liquefied flammable gas escaped under pressure from the site from which the valve had been removed. And those who brought the pump back into service were not aware of the work on the line downstream.
That there was insufficient time for evacuation is controversial, to say the least. People were still getting off the platform several hours after the initial fires and explosions.
Another contributing factor was that a nearby platform (the Tartan) continued to pump gas into the heart of the fire until its pipeline ruptured in the heat. The operations crew on the Tartan did not have authority to shut off production even though they could see that the Piper was burning.
“How you might ask, were they not aware of this major emergency that had such obvious, direct and significant effect on their own actions? There must have been serious health and safety management failures.
“One of the main lessons of this major emergency was that managers must be ready to override an emergency procedure when it is clear that is no longer the correct course of action. Therefore, we need managers who can use their initiative, such that if the original plan breaks down, they will improvise a better alternative. Every rule is made for a good reason, but there may be times when actions need to be taken, that are not in accordance with the plan.
“In other words, the people in charge must be ready to depart from the plan if it ceases to be feasible. EMP needs people who have enough intelligence and experience to know when to override the plan. Because when it is clearly not working, the plan needs to be overridden.
“One lasting effect of this disaster is that legislation was improved. A major reappraisal of emergency procedures both in plans and in safety systems in the Cullen report was undertaken. Though, it is a sad fact that a major disaster had to happen first before upgrade on safety standards were done,” Perry added.
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. Piper Alpha’s operator, Occidental, was found guilty of having inadequate maintenance procedures. A second phase of the inquiry made far-reaching safety recommendations, all of which were accepted by industry.
Common Lethal Mistake
The offshore industry faces many risks, coming from fire and explosion, hydrogen sulphide (H2s), oil spills, platform damage and terrorism. Crude oil, when it is in the underground reservoir, is a combination of many products – methane, commonly sold as natural gas or liquid natural gas (LNG); butane and propane, commonly sold as liquid petroleum gas (LPG), gasoline, kerosene and diesel.
When the oil is produced at the wellhead, it is taken to facilities either offshore or onshore that strip out the lighter gases, so that the oil can then be safely loaded into an oil tanker for transport to the refinery.
“At any stage in these process facilities, as all of these products are highly flammable, they are highly dangerous if released, which can lead to fire and explosion. The heavier fractions are less flammable, but if there is a platform fire, they also burn and contribute to the overall disaster,” Perry explained.
“Not only that. Many Middle East crude oils are sour, which means they contain sulphur. This manifests itself as hydrogen sulphide gas, which is highly toxic and has lethal concentrations that anaesthetise the sense of smell and this has resulted in many fatalities. “In my own experience in the North Sea, on one occasion an operator collapsed in a confined room due to this gas. Two other people, one of them the platform manager, rushed in to help. The next thing we knew, all these three people died.”
He emphasised that H2s, in low concentration smells like rotten eggs, but as the concentration increases, it anaesthetises the nose, and the presence of the gas can only be detected by special meters.
“H2s is a very common gas in the oil fields and precautionary measures and training in dealing with this gas are commonplace. If somebody collapses within a confined room, staff are trained to overcome their natural inclination to put on some breathing apparatus, and not just simply rush in.
“This common mistake has unfortunately happened on other occasions, as I am told of similar stories by other experts here in the region. The lesson is: for all emergencies, we should think first before we act. Always.”
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