An investigation by Statoil found that a recent leak at its Gudrun platform could have been fatal if workers had been exposed to the released gas.
A condensate leak was first detected at the platform on February 18 during normal operations in the Norwegian North Sea and triggered a shutdown.
No injuries were reported and no personnel were present in the affected area when the leak occurred.
Statoil investigators found a 2 mm wide crack extending across 90 percent of the circumference of a two-inch pipeline that was caused by “fatigue and overload.”
The report found that an under-dimensioned level valve caused vibrations in the valve and surrounding piping system during regular plant operation, eventually leading to a loss of level valve control.
The loss of valve control caused “repeating powerful vibrations and strokes in the piping system which exceeded the design capacity,” Norway’s Statoil said.
No material defects, metallurgical irregularities or welding defects were found.
Condensate leaked from the pipeline and resulted in gas distribution at a rate of about 8 kilograms per second.
The volume of condensate released during the leak is estimated to 4 cubic meters.
Gudrun’s deluge system, pressure relief system and emergency shutdown system all started automatically once the leak was detected.
“When the leak occurred, the emergency response system functioned as intended,” Statoil senior vice president of the operations south cluster of Development and Production Norway Bente Aleksandersen said.
The investigation team said it was “pure chance” that a full pipeline break was prevented and that the outcome could have been fatal if anybody had been exposed to the leaked gas.
The company added that a gas leak of this size “represents a major incident potential if ignited.”
“Statoil is working systematically on gas leak prevention, and the learnings from this incident shall be translated into specific actions. We must ensure that these efforts help prevent future incidents,” Statoil senior vice president of safety and sustainability of Development and Production Norway Øystein Arvid Håland said.