Near-miss: Dropped steel plate

A member has reported a near miss incident in which a steel plate weighing over 1kg fell at least 4.8m to the ground.  The incident occurred when a vessel main crane was being prepared to recover a work basket from the seabed.  A rigger (banksman) was assisting the crane movement by dogging the crane boom out of the crane crutch (boom rest) – in accordance with company lifting operations procedures.  As the crane boom rose, the rigger heard two distinct noises of a dropped object.

Upon investigation, a steel plate (1.38 kg), later identified as sea-fastening dog plate, had fallen from the crane crutch, struck an access platform and fell a further 4.82m to deck.  While there was no-one in the vicinity at the time, according to the Drops Calculator the falling steel plate had the potential to cause a serious injury.

Our members’ investigation noted the following:

• Following examination of the crane crutch along with records of recent dropped object inspections of the area, it was concluded that the dog plate had been placed on the crane crutch Teflon pad and the movement of the crane boom as it was raised and lowered out of the crane crutch over a period of time, had ‘rocked’ the plate aft to the edge of the pad until it fell;
• The dog plate did not originate from the project and was of an unknown origin.  The vessel had been in a shipyard for crane refurbishment work.  This had included scaffold work around the crane crutch immediately before mobilisation;
• The dog plate had been used by the scaffold team that worked on the crane crutch.  It was likely that the plate had been placed, inadvertently or otherwise on the crane crutch Teflon pad by one of the scaffold team;
• The root causes of this incident were an inadequate crane boom inspection process and inadequate control or supervision of the yard scaffold crew.

Conclusion and lessons learned:

• Dropped objects often can be attributed to a lack of access for proper dropped object inspection;
• Crane boom rests are a common source of dropped objects due to the dynamic nature of landing crane booms and the lack of easy access to the top of the crane boom rest for inspection of the pads and fittings;
• Crane boom rests and all items located on the rest should be subjected to regular and robust dropped object inspection through a planned maintenance system;
• Drops or Crane Boom Rest Inspections should be conducted in a manner where there is clear visual assess to boom pads either by direct access or other acceptable means;
• Drops inspection report sheets should provide clear instructions and guidance on conducting a robust drops inspection and should be added to Planned Maintenance Work Orders for completion;
• Supervisors controlling maintenance or refurbishment works of third party contractors should be satisfied that the worksite is safe and in good order upon completion of all works.

Dropped object incidents or near miss incidents comprise 12% of all the incidents reported to IMCA during 2016. Members attention is drawn to Near-miss: Dropped object from crane, which includes a summary and links to all the dropped object incidents reported in the last two years.