Alert 22-06 Semi-submersible MODU Total Failure During Severe Weather Event

WHAT HAPPENED:

On a semi-submersible MODU during a severe weather event, the chain lifter on Anchor Winch #1 experienced total failure. The chain lifter was split into two halves by tension exerted on the anchor chain via the fairlead and over the chain lifter. This resulted in loss of both the anchor chain and tail chain to the seabed.

Metallurgical analysis identified that the chain lifter had a manufacturing defect consisting of a significant cavity extending over approximately 1/3 of the cross-sectional circumference and thus reducing the wall thickness to around half in comparison to the solid unaffected portion…