At 22:16 on 7 January 2016, during normal operations, a gas leak was detected in the Statpipe receiving area at Kårstø.
A nearly complete fracture occurred in an instrument fitting with an interior tube diameter of 9.1 mm. When the leak started, the pressure in the affected system was around 140 bar.
The initial leak rate is estimated to be 1.3 kg/s. The gas leak lasted for 9.5 hours and the leaked volume is estimated to be approx. 22 metric tonnes.
The leak occurred due to a fatigue fracture in a free standing instrument fitting pipe branch. The fatigue fracture was due to bend stresses from wind loads in combination with lack of adequate pipe supports and coincidence between the system's natural frequencies and the vortex induced vibration frequencies at normal wind speeds.
The reason that the leak lasted as long as 9.5 hours was an absence of pressure relief opportunities from the control room for the processing segment where the leak occurred.
No-one was injured in the incident and the material damage was minor. However, the incident did have escalation potential relating to possible ignition of the gas leak, where parts of a gas-transporting pipe could have been exposed to jet fire and heat radiation.
If personnel had been in the proximity of the leak in the event of ignition, this could have caused serious personal injuries and potential fatalities.
The PSA's investigation of the incident has identified non-conformities linked to mechanical bracing of instruments, learning and improvements and deficient plans for pressure relief in an emergency situation.
Furthermore, improvement points were identified linked to assessments of manometers and associated instrument fittings, notification/summoning of 2nd line emergency response team, and faults in P&ID.
We have asked the operator to provide an account of how the non-conformities will be dealt with.
The Kårstø gas processing and condensate facility is in Tysvær in Rogaland county. The operator of the Kårstø facility is Gassco and Statoil is the technical services provider.