An incident occurred while performing a proof load test on a crane which resulted in 3 persons falling overboard (2 were rescued and the third was not recovered) and catastrophic structural failure of the crane. The incident occurred following failure of the boom foot pins which caused the boom to come off the chassis at the foot pins, hitting the cab, knocking it off its mountings and allowing it to fall over the side. Three persons who were in the cab at the time were thrown into the sea.
Observations Noted During the Investigation – Conditions / Inactions
Investigation has revealed that the cause of the boom foot pin failure was due to excessive side loading being applied during the load test. Underlying causes which led to the failure include:
- Load test procedures did not take vessel dynamics into account.
- Crane Load Indicator was not correctly calibrated prior to load testing. This resulted in the test load being held for more than 20 minutes while calibration was being performed.
- The API 2C 5th Edition standard does not give an adequate safety margin for static proof load testing in dynamic conditions on a floating vessel. Per API 2C 5th Edition, the proof load test was conducted using the Static (onboard lift) Load charts since the lifting was from the crane supporting structure. Since the test occurred in open water the vessel was subject to open sea and dynamic conditions. This issue is addressed later in the API 2C 6th Edition with the definition of onboard load charts at different sea states/dynamic conditions.
What Should We Do Now? – Corrective Opportunities
Rig Manager and OIM to ensure immediate Corrective Actions to verify:
That all Rig Managers, OIM’s, Maintenance Supervisors, Deck Foremen, Masters/Barge Supervisors and Crane Operators have read the following documents and understand the content:
- • HQS-OPS-EAL-CRN-010 – Crane Safe Load Indicator Operation / Calibration.
- • HQS-OPS-TIB-CRN-014 – Load Test Of Pedestal Crane
Corrective action items will be pushed to all installations in FOCUS by Corporate QHSE. Specific action plans to be developed, tracked and closed in FOCUS by September 15, 2011.