The incident occurred during repairs to the port drag chain on the jack-up drilling facility, which is operated by Odfjell Technology (Odfjell).
A drag chain is a linked cable/pipe tray carrying power cables and hoses to supply water, drilling mud and air to the cantilevered drilling rig when the latter is skidded between various well slots.
Measuring 115 centimetres wide, the port drag chain on Linus comprises two cable trays, one atop the other. One of its outer plates was damaged (bent), and a two-member team comprising the injured person with assistant were to look at this and consider what to do.
The injured person had undone the nuts on a damaged side plate in one of the drag chain links. He was lying between the upper and lower drag chain when the upper section collapsed. Parts of the chain dropped and compressed his arm and head.
The weight of the collapsed structure was considerable, with the load cell on the offshore crane showing about two tonnes when the police came to secure the injury site for their investigation.
Actual and potential consequences
The injured person’s head and left arm were compressed. Crushing injuries meant his arm had to be amputated between shoulder and elbow.
His assistant suffered no physical injury during the incident.
The drilling operation was halted for 48 hours from the time of the injury.
In minimally different circumstances, this incident could have had a fatal outcome for both the injured person and his assistant.
Direct and underlying causes
The most important direct cause was the collapse of the drag chain over the injured person. This occurred after he had undone several nuts on a damaged side plate for workshop repair. The job was not registered, planned or risk-assessed in accordance with the requirements in the company’s governing systems.
Underlying causes were a lack of control and management of technical condition, lack of job control, deficiencies in governing documents and procedures, and inadequate handover routines and clarification of roles and responsibilities.
The incident occurred the day after a swing shift from night to day work. It is unclear whether this might have affected the assessment of risk posed by the repair work.
Seven nonconformities and one improvement point were identified.
- registration and classification
- procedures and work description for the drag chain
- roles and responsibilities
- decision basis and safety clearance
- compliance with governing documents
- information at shift and crew changes.
- mustering and POB.
What happens now
The investigation has been completed.
The PSA has given Odfjell until 23 March 2023 to explain how the nonconformities will be handled, and to provide its assessment of the improvement point observed by the investigation.