Hydrogen-rich gas escaped on 25 October 2017 during work on a petrol plant at the Mongstad refinery. The leak occurred when an operator, after gas had been detected in the area, attempted to operate a valve. That caused the pipe end carrying the valve to break off so that the gas could freely escape. The pipe had rusted through owing to corrosion under insulation (CUI).
Emergency shutdown and manual blowdown were initiated, and personnel evacuated the plant.
Known
CUI is a known problem at Mongstad. Another serious incident caused by CUI, involving a steam leak, occurred at Mongstad in 2012. This incident was investigated by both Statoil and the PSA. Other and less serious leaks have occurred in the meantime.
Potential
Under slightly different circumstances, the gas leak could have caused loss of human life.
Nonconformities
Serious breaches of the regulations have been identified by the investigation.
- The plant has not been maintained to an acceptable standard.
- Risk assessment before commencing an activity has been inadequate.
On the basis of the findings from its investigation, the PSA has given Statoil the following orders:
Pursuant to section 69 of the framework regulations on administrative decisions, see section 58 of the technical and operational regulations on maintenance, we order Statoil to establish robust plans for the surface protection programme at the plant in terms of resources and time. The plans must ensure that the plant at Mongstad is maintained to an acceptable standard. See section 7.1.1 of the report.
Pursuant to section 69 of the framework regulations on administrative decisions, see section 55 of the technical and operational regulations on planning, we order Statoil to establish measures which ensure that risk related to further planning and execution of the surface protection programme at the plant is assessed and dealt with in an acceptable manner. See section 7.1.2 of the report.