Wire inserts in anchor line parted

A member has reported an incident in which wire inserts parted in two anchor lines of a semi-submersible accommodation unit connected to a fixed platform during extreme weather conditions (9 m seas, 70 knot winds). Non-essential personnel were taken off the semi-submersible accommodation unit until the mooring system could be safely recovered and replaced.

During recovery of the mooring system it was discovered that the wire inserts in both the affected mooring lines had slipped out of the socket at the rig end. The wire inserts were taken ashore for investigation.

Following investigation the following was noted:

• the failed wire inserts had not been moulded on to the sockets using proper procedures;
• the supplier of the failed wire inserts was not aware of the procedure and its personnel were not formally trained in the moulding operation;
• the supplier of the wire inserts and other contract-specific anchoring equipment had not been audited by this or any other customer;
• similar incidents regarding wires slipping out of sockets had occurred but had not been brought to public attention;
• there was a detailed investigation of the design of the mooring system. The system used mooring lines supported by buoys, but it was not possible to ascertain that this was directly causative.

The company recommended the following:

• higher awareness of procedures for moulding sockets on to wires and increased training for personnel engaged in such work to ensure that personnel involved are properly qualified for the work;
• audit of suppliers of contract specific mooring equipment for appropriate quality management system;
• free sharing of similar incidents to prevent recurrence of incident;
• research into testing wires with moulded sockets.