Norwegian offshore safety body, the Petroleum Safety Authority (PSA), has identified weaknesses in crane design as an underlying cause of a crane incident from March on Statoil’s Gullfaks B platform offshore Norway.
The PSA said on Thursday it had finished its investigation of the incident on Gullfaks B from March 7, 2017, when the boom of the pipehandling crane fell to the pipe deck. Several breaches of the regulations have been identified by the regulator.
According to the agency, while transferring materials from the pipe deck to the drill floor on the Statoil-operated installation in the North Sea, the boom dropped 10 meters without warning to the pipe deck after a steel rope failed. The boom weighed about 14.4 tonnes.
The horizontal to vertical (HTV) Eagle crane is used, as its designation suggests, to lift drill pipe from a horizontal position on the pipe deck catwalk to a vertical position on the drill floor.
Two people had adjusted the gripper on the crane’s gripper yoke down on the pipe deck immediately before the incident.
Actual and potential consequences
The safety body said in its report that the actual consequence of the crane boom falling onto the pipe deck was substantial material damage to the crane and to the cable tray for the traverse crane on this deck. In addition, the incident caused a halt to activity on Gullfaks B. No personnel were injured in the incident.
Under slightly different circumstances, the incident could have caused serious personal injuries or loss of human life. In other circumstances, it could have given rise to even greater material damage, the offshore safety watchdog said.
Direct & underlying causes
Further according to the report, the direct cause of the boom falling to the pipe deck was fatigue in the steel rope. The underlying cause was weaknesses in the design of the crane’s hoisting system, which gave rise to wear and fatigue in the rope over time. Fatigue in the steel rope was not assessed as a relevant problem for this design.
Nonconformities from the regulations
The investigation has identified several nonconformities from the regulations, including: Risk assessment of equipment – inadequate identification of risk; Investigation of and improvement measures following earlier incidents – inadequate identification, investigation and follow-up of previous hazards and accidents; Utilization of expertise – insufficient use of mechanical handling expertise when specifying crane requirements; Responsibility for acceptance and operation of equipment – inadequate follow-up and checks when taking delivery of and operating machinery and equipment; Maintenance – deficiencies in the maintenance program for the steel rope.
Statoil has been asked to explain to the PSA by September 20, 2017 how it intends to deal with these nonconformities.
The main Gullfaks field lies in block 34/10 in the northern part of the Norwegian North Sea. It has been developed with three large concrete production platforms. The Gullfaks A platform began production in December 1986, with Gullfaks B following in February 1988, and the C platform in November 1989.
The A platform is also used for storing and exporting stabilised crude from the Vigdis and Visund fields. Oil and gas from Gullfaks B is transferred to the A and C platforms for processing, storage and export.