Aug 242010

The crane pennant and the Flemish eye tails which have unravelled and pulled out of the ferruleA badly made Flemish eye crane pennant failed on an offshore installation dropping of a 9.5 tonne load causing what the UK’s Heath & Safety Executive calls “a serious incident. Inadequate testing by the manufacturer and incomplete technical information lead to the Flemish eye being manufactured with a mismatched ferrule/wire rope arrangement.

This incident occurred on an offshore installation during the lifting of a container weighing 9.5 tonnes. A 5 metre long, 15 tonne working load limit crane pennant was connected between the crane hook and the master link on the container sling set. The crane pennant had been manufactured from 36mm diameter wire rope and the eyes on each end had been formed by using the Flemish eye technique. Steel ferrules had been used as the termination and these had been pressed over the Flemish eye rope strand tails. During the lifting of the load the wire rope strands in the tails of the Flemish eye connected to the pennant hook became free inside the ferrule allowing the Flemish eye to unravel and the load to fall. A Flemish eye rope termination is an eye formed at the rope end by dividing the rope strands into two sections and then splicing these ends to form a loop. The ends of the loop, or tails, are secured by a metal ferrule that is swaged onto the main body of the rope in a press.

A crane pennant is the term used in the offshore industry for a single leg sling with a master link at one end and a hook at the other. The master link attaches to the crane hook block and this ensures personnel attaching and detaching loads on a potentially moving offshore installation or supply vessel are not exposed to the swinging, large mass, crane hook block.

Says the HSE alert: “The ferrule-secured system designers published instructions detailed the ferrules that should be used for particular rope diameters. However, 36mm diameter rope was not listed. The crane pennant manufacturer had selected a ferrule, 1.5″, and considered sufficient tests had been undertaken to verify this selection. This incident has highlighted that these tests did not fully replicate the dynamic, tensile and torsional, loading experienced by an offshore crane pennant.”

Wire rope slings and crane pennants with Flemish eye terminations have been used extensively in the offshore industry for a considerable number of years. They have proved to be very reliable but it is essential the ferrule-secured system designers published instructions are followed. HSE warns: …other manufacturers may have supplied Flemish Eye slings and crane pennants with rope diameters to ferrule combinations that are not listed in the ferrule-secured system designers published data, in the belief they have undertaken appropriate type testing to verify this change.”

Users are advised to:

  1. Check whether wire rope slings and crane pennants with Flemish eye terminations are in use.
  2. Verify with the supplier or manufacturer that the rope diameter to ferrule combinations used in the construction are in agreement with those published by the ferrule-secured system designer.
  3. In the case of combinations, which are not in agreement, obtain verification from the supplier or manufacturer they can satisfy point 2 below.
  4. Where such verification cannot be obtained, remove these slings from service.

Manufacturers and suppliers of Flemish eye wire rope terminations should:

  1. Only supply wire rope slings and crane pennants that adhere to the ferrule-secured system designers published combination of rope diameters to ferrule sizes.
  2. Any additions to these published combinations should only be undertaken with the agreement of the ferrule-secured system designer and verified by a range of type tests representative of the dynamic loadings that will be experienced in service. The results of these type tests should be made available to users if requested.
  3. Where slings and crane pennants have been supplied which do not meet the above criteria contact their customers and advise them to remove such items from service.

The HSE alert is available here.

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