During a lifting operation on board one of our members’ ships, when an 82.5 te riser anchor was to be installed on the seabed, the main crane wire parted after the load had been swung away from the deck, causing the anchor to drop to the seabed. Fortunately no one was injured.
The cause of the crane wire separation appears to have been due to slack being paid out during hook up whereby the wire over ran the sheave’s flange. When the load was raised, the wire slipped over the sheave and ended up bearing on the sheave pin rather than the sheave itself. As a result the wire’s lifting capability was severely degraded since it was subject to the sharp bend radius and as a consequence parted.
The contractor involved as implemented the following:
- Checks to be made on all cranes to ensure that the lift wire cannot come out of the sheave(s) either on the jib or lifting block during lift operations.
- A viewing arrangement has been installed to ensure that the crane operator can see that the wire fits centrally in the sheave(s) during lifting operations.
- As an additional precaution, just prior to raising the load, when the full load comes onto the crane wire, the person directing crane operations on deck should view the sheaves, if practical, to ensure that the lift wire is correctly located.