The Petroleum Safety Authority Norway (PSA) has completed its investigation of a fire on Petrojarl Knarr FPSO, located offshore Norway, during March 24, 2015. The safety watchdog has identified design errors and faulty operations of the HVAC system as a direct cause of the fire.
Petrojarl Knarr is a floating production, storage and offloading (FPSO) facility on the Knarr field that lies in the Norwegian North Sea. The field has been developed with Petrojarl Knarr and two subsea templates for production and injection tied back to a seabed manifold.
Teekay Petrojarl Production is the FPSO’s owner, responsible for operating it, while BG Norge Limited is the operator of the field.
A fire broke out during the early morning on March 24 in the ventilation system on the Petrojarl Knarr on the Knarr field. The unit concerned supplied air to the engine room beneath the living quarters.
According to the PSA, this event had been preceded by a power cut which shut down the fans in the HVAC unit. However, steam continued to be supplied to its heat exchanger and that caused high temperatures to develop in the unit, and air filter cassettes ignited eight hours later.
Technical investigations by the vessel’s owner have been unable to identify the direct cause of the filter ignition with any certainty. Had the fire damper valves failed to operate, smoke could have spread into the living quarters and it could also have disseminated via other rooms, the safety authority said.
The PSA stated the filter cassettes ignited in air handling unit A (AHU-A) for the forward engine room as a result of design errors and faulty operation of the system.
The incident led only to material damage that was limited due to response of the fire-fighting personnel. Without their efforts, this would probably have been greater for both AHU-A and AHU-B, the PSA said.
A number of nonconformities and improvement items have been identified by the PSA’s investigation covering both technical conditions and areas related to emergency response.
They include nonconformities concerning the use of and knowledge about the start-up procedure for the HVAC unit after a power cut, and inadequate testing of the system before start-up. Namely, the yard which built the FPSO (Samsung) was responsible for commissioning the system before start-up but, according to the PSA, a verification of the commissioning documentation shows that the steam valve and associated temperature control functions were not tested.
Nonconformities and improvement points were also identified with regard to unclear division of responsibility for day-to-day operation and follow-up of the HVAC system; emergency preparedness, including deficiencies related to analyses; and to training of the emergency response team.
The PSA has asked Teekay Petrojarl Production AS to respond to the nonconformities identified in this report, including any follow-up actions.
The Knarr field lies in the Norwegian North Sea, about 50 kilometres north-east of Snorre, and has been developed with Petrojarl Knarr and two subsea templates for production and injection tied back to a seabed manifold.
Petrojarl Knarr was installed on the field in the fourth quarter of 2014, and came on stream on March 18, 2015.
Offshore Energy Today Staff