ConocoPhillips UK’s prosecution followed three gas leaks in two days on the Lincolnshire Offshore Gas Gathering System (LOGGS) in the North Sea, which threatened the lives of more than 70 staff.
The LOGGS complex comprises five interlinked platforms. It has its own wells and also feeds natural gas from other platforms to the Theddlethorpe terminal on the Lincolnshire coast.
On 30 November 2012, two gas releases took place during maintenance work to refit a Hale Hamilton fuel pressure control valve on one of three gas turbine electricity generators that provide LOGGS’ electrical supply.
Two fitters operating under a permit to work had ensured the gas feed to the control valve was isolated, but as part of the refit they also removed a pressure safety valve above the Hamilton Hale valve, along with a 10 cm flexible hose. The hose connected the safety valve to a high pressure venting system, which releases excess gas from equipment on the platform.
Having reinstalled the Hale Hamilton valve but not the pressure safety valve or hose, the fitters left the turbine hall for a tea break with other workers in the adjacent platform, which housed the accommodation block.
Elsewhere in the complex, LOGGS workers were depressurising a sphere launcher, used to project a ball under pressure through pipelines to clean them. On another part of the installation a compressor was being powered up. The exhaust from this operation and gas released from the sphere launcher flowed into the high pressure vent which would normally have diverted it tens of metres up the platform’s vent stack to be dispersed harmlessly into the air.
The missing hose caused methane to vent directly into the turbine hall, triggering an alarm. Since multiple gas detectors registered the release, the system went into an automatic “blowdown”, a safety measure that reduces the hazard by venting all LOGGS’ stored gas. But the venting gas also had to pass through the high-pressure vent, so though almost 8.5 tonnes vented through the stack, 603 kg filled the turbine hall.
HSE inspector John Hawkins said if the gas in the hall had ignited it could have threatened the 66 employees in the accom¬modation unit metres away and those passing the hall on their way to the muster station.
Immediately after the blowdown, the installation manager was not able to assess the status of the complex without leaving the accommodation block because of a fault in the emergency monitoring system.
“Effectively, they didn’t know where the incident had occurred,” said Hawkins. Another system fault led the manager to believe all the gas had vented from the platform, whereas the blowdown was only partial. Seven workers were sent out at high risk with gas detectors. They vented the turbine hall by propping the door open.
When the night shift operator, Geoffrey Robinson, came on duty, he traced the problem to the missing hose and valve and closed an adjacent valve, VH217.
The safety system triggered a second blowdown the next day, releasing the residual gas, when the batteries of LOGGS’ uninter¬ruptible power supply ran down. Only Robinson’s closure of VH217 prevented another release in the turbine hall.
“It could have happened earlier,” said Hawkins of the power loss and blowdown, “and if there had been people in the turbine hall it could have been awful.”
He said there was nothing wrong with ConocoPhillips’ procedures, “other than that they weren’t being followed.
“The planning was awry,” he added. “Some of the permits weren’t filled in properly and some of the risk assessments hadn’t been completed properly.
“If someone who was associated with the permit had actually gone out to the workplace and looked for themselves they would have seen that it wasn’t just a case of taking the Hale Hamilton valve out and putting it in again. There was more to it.”
He said no one consulted the system’s installation drawings before the work started.
A review of permits showed that valves had been replaced on the other two turbines during the year without full isolation of the gas supply, risking similar releases.
The HSE served ConocoPhillips with a prohibition notice on 13 December 2012 and on 21 December confirmed that LOGGS’ incident command system had been modified to prevent similar incidents.
The company pleaded guilty at Lincoln Crown Court to three breaches of the Offshore Installations (Prevention of Fire and Explo¬sion, and Emergency Response) Regulations 1995 for failing to prevent uncontrolled hydrocarbon releases. On 8 February it was fined £3m plus £159,457 in costs.
Judge Pini said: “A company the size of ConocoPhillips with its vast resources really has no excuse for failure in this regard.”
Since the sentencing hearing had begun on 22 January, before the new sentencing guidelines came into force, he noted he was not bound by their terms. He weighed the firm’s early guilty plea, cooperation with the HSE and the fact it had not ignored previous warnings or put profit before safety, but said the penalty had to “bring the message home” to shareholders. He said if Conoco- Phillips had contested the case he would
have set the fine at £5m.