High potential near-miss: SWL plate fell from crane auxiliary block

A member has reported a near miss incident in which an object – a steel SWL plate weighing 0.7 kg -fell from a crane block onto the deck. The incident occurred when a crane fast line was being used for loading operations from the quayside. A banksman and two riggers were on the quay in the process of choking off the lifting slings and connecting them to the crane fast line hook. During this task a steel SWL plate (0.7kg) fell from the Crane Auxiliary Block which was not being used at that time. The SWL plate fell from approximately 71m in height and landed at approximately 5m away from the working party. The DROPS calculator tells us that such an object falling from such a height could have caused a fatality had it hit someone.

An all stop was called immediately and the crane was taken out of service.

Our member noted the following:

• The SWL plate fell from the crane auxiliary block and there were similar plates still on this block and on the main block. Both these blocks, and the whip line block, had all been replaced during the re-fit period to enable the crane to operate subsea for a particular project;
• The means of securing the plates was of poor design – several plates including the one dropped were attached by four rivets of dissimilar metals (aluminium vs steel) promoting galvanic corrosion process and salt water corrosion;
• All plates showed signs of corrosion behind the plate – however deterioration of the rivets was not visible on the plate surface;
• All plates were flush against their fixings and looked secure to any visual inspection;
• There was no significant weather at the time of the incident.

The plates were removed. SWL and other identifying information was stencilled on the crane instead. There was an inspection of similar hook blocks elsewhere to verify that there were no loose objects or unsecured plates. The crane supplier/manufacturer was informed of the incident (lessons learnt to prevent further reoccurrence).

There had been a rash of similar incidents in recent years where objects not relating to the load have fallen from cranes. members may wish to refer to the following incidents (search words: crane, dropped):

• Crane boom dropped object
• Dropped object near-miss – Unsecured plastic box fell from load being lifted by mobile crane
• Dropped object near-miss: Falling crane block
• Near-miss: Dropped object fell from crane boom

Members are reminded of Guidelines for lifting operations.