Crane wire failure

A member has alerted IMCA of a failure of a crane wire during the recovery of an ROV. As the ROV was being swung inboard by the ROV system, the crane wire snapped just as the ROV was above the platform rail causing the ROV to hit the rail and fall inboard on its side.

Fortunately no-one was injured and no major damage was sustained by the ROV. The investigation has shown that the crane wire was weakened by the hook being drawn fully up into the sheave at the end of the crane, then the crane articulated sections operated in a manner that over stressed the wire. This caused it to weaken. The wire, outwardly, was in very good condition and had only been offshore in service for five weeks.

The contractor has issued the following instructions to its personnel as a result of the incident:

1. Keep all personnel well clear of loads being manoeuvred by lifting equipment.
2. Persons operating cranes or A-frames should ensure that enough slack is maintained in a wire to allow for changes in the crane/A-frame geometry.
3. If, by inspection of the ferrule on the hard eye of the crane wire, there is evidence of distortion or damage that could have been caused by pulling the hard eye into the crane end sheave, or it is known that the crane wire has been overstressed in the above manner, then the crane wire should be changed at the earliest opportunity.