The release of over two tonnes of high pressure, high temperature natural gas would ‘almost certainly’ have killed workers who had been celebrating away from the blast on the day of the incident, 26 December 2015.
It was heard at Aberdeen Sherriff Court how 100 personnel on board the Brae Alpha platform had been enjoying a Boxing Day buffet meal and games when they heard a loud bang, which occurred at 16:30 hours. The lights went out, gas alarms were triggered and emergency response teams called. There were no deaths or injuries thanks to workers being away from the blast in the 'refuge area'.
The full realities of the near miss of the blast however were conveyed to court at sentencing on 20 May.
The incident occurred in Module 14, containing electrical equipment, and where staff had been working that morning. Staff on board also described Module 14 as being a “thoroughfare”. Three staff had been about to take their normal route through Module 14 after the blast, but one of the more experienced crew member prevented them from entering and they used an alternative route.
The explosion’s force had been sufficient to bend metal hand rails and industrial cables, heard the court. Anyone within several metres of it could have been killed or injured.
According to the Crown narrative obtained by Safety Management staff could have also suffered from narcotic effects of breathing in the methane and the risk of asphyxiation from depleted oxygen levels in the area. "Personnel in the vicinity of the release could also have been exposed to injuries by flying metal debris," it read.
HSE calculated that the mass of gas released was 2,148 kilograms. The release lasted a total of 25 seconds with every single second releasing an average of 86 kilograms of gas.
HSE’s investigation had found that the pipe had ruptured as it had become corroded over a lengthy period of time. The corroded area had been hidden from view as the pipe was covered by insulation and cladding, known as Corrosion under insulation (COI).
A risk assessment had undertaken in 2010 which recognised that CUI posed a risk to insulated pipework and in fact it identified Module 14 as a vulnerable location. This is because the area contained a sprinkler system that uses sea water to extinguish flames in the event of a fire. When the system was tested it exposed the module to sea water. “The water entered the pipework’s insulation and the process of corrosion was allowed to begin,” read the statement.
A Marathon ‘strategy’ document was found which noted that ‘all pipework should be visually inspected on a 36 month interval and minus its insulation at least once every 144 months (12 years).’
But the pipework that failed had been in service for 26 years and Marathon had failed to implement it. There had never been a close visual examination of the pipework. This did not stop Marathon reviewing their risk assessment in 2014 and approving the pipework as being suitable for continued use.
Marathon is a foreign company with an overseas address of Wilmington, Delaware, USA. Marathon has registered addresses in both London and Aberdeen with their European operations headquartered in the latter.
The company is headquarted in Texas and globally reported a turnover of US$ 5.522 billion in 2015.
Marathon pleaded guilty to breaching Regulation 4 (1) of the Offshore Installations (Prevention of Fire and Explosion, and Emergency Response) Regulations 1995 and Section 33(1) of the Health and Safety at Work Act 1974, at Aberdeen Sheriff Court. It was fined £1,160,000.
Marathon Oil was jointly prosecuted by HSE and Crown Office and Procurator Fiscal Service in Scotland.
Investigating HSE inspector, Ahmedur Rezwan, said: “This incident is a further reminder of the ever-present hazards in oil and gas production, that if not rigorously managed can easily result in a potentially life-threatening event.”
“Corrosion Under Insulation (CUI) is a well-known risk and this incident should not have occurred. During any normal period of operations personnel could easily have been working in, or transiting through Module 14, and they would almost certainly have been killed or suffered serious injury. The timing of the incident and fact that the gas did not ignite was fortuitous.”
Alistair Duncan, Head of Health and Safety Investigation Unit at the Crown Office and Procurator Fiscal Service said: “Corrosion under insulation is a well-known issue in the petrochemical industry. “This incident could have been prevented had suitable and sufficient measures been put in place. By failing to take these measures in respect of the failed pipeline Marathon exposed Brae Alpha personnel to risk of fire and explosion.
“Hopefully this prosecution and the sentence will remind other employers that failure to fulfil their obligations can have potentially very serious consequences and that they will be held to account for their failings."