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The dropping of a 9.5 tonne load on an offshore installation as a result of the incorrect manufacture of a 15 tonne Flemish eye crane pennant

Health and Safety Executive - Safety Notice
Department Name: Hazardous Installations Directorate (Offshore Division)
Bulletin No: OSD 6-2010
Issue Date: 10 August 2010
Target Audience: Offshore oil and gas industry, wire rope sling manufacturers
Key Issues: This safety notice describes a serious incident resulting from the incorrect manufacture of a Flemish eye crane pennant and outlines the actions that should be taken by users and wire rope sling manufacturers.

Introduction:

This safety notice describes a serious incident caused by the incorrect manufacture of a crane pennant. It outlines the actions that should be taken by both the users and the manufacturers of Flemish eye crane pennants and slings.

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 (tails) are secured by a metallic 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.

Background:

This incident occurred on an offshore installation during the lifting of a container weighing 9.5 tonnes. A 5m 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. The photograph shows the crane pennant and the Flemish eye tails which have unravelled and pulled out of the ferrule.

The ferrule-secured system designers1 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.

Action required:

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 considers that 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 (ferrule-secured termination manufacturer) 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.

Relevant legal documents:

References:

Note 1

To aid clarity, the following definitions are copied from BS EN 13411-3.

ferrule-secured system designer
person or organization that designs the ferrule-secured eye termination or ferrule-secured endless loop and assumes responsibility for type testing

ferrule manufacturer
person or organization that manufactures ferrules for a ferrule-secured eye termination or ferrule-secured endless loop system

ferrule-secured termination manufacturer
person or organization that manufactures the FSET and/or ferrule secured endless loop in accordance with the ferrule-secured termination system designer's instructions (i.e. the pennant manufacturer)

Further information:

Any offshore industry queries relating to this Safety Notice should be addressed to:

Team Leader - Mechanical Systems
Health and Safety Executive
Hazardous Installations Directorate
Offshore Division
5N.2 Redgrave Court
Merton Road
Bootle
Merseyside L20 7HS

General note:

Please pass this information to a colleague who may have this Product/Equipment or operate this type of system/process.

2011-07-28