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Identical letter on danger of using flat-braided steel slings

The Petroleum Safety Authority Norway has informed manufacturers, importers and suppliers in identical letters about the danger of using flat-braided steel slings.


Information on the hazard posed by this product emerged from the PSA’s investigation of the lifting incident on Maersk Interceptor. This accident on 7 December 2017 caused the death of one person and serious injuries to another.

The letter was sent on January 29, 2018, while the investigation was still ongoing. The investigation was completed in April 2018.
Read: Report after the investigation of the fatal accident at Maersk Interceptor (3 May 2018)

The PSA investigation has revealed that one of the causes of the incident was the failure of a flat-braided steel sling with a working load limit (WLL) of 4.8 tonnes. This sling was used for a U/V lift where both its loops were attached to the load with the aid of shackles.

Tests with the same type of sling from five different manufacturers have shown that they lack the necessary rupture strength in relation to the requirements specified in Norway’s FOR-2009-05-20-544 machinery regulations, which demand a safety factor of five, or the SDFor 1978-01-17-04 regulations from the Norwegian Maritime Authority, where the safety factor is set at six.

In addition to testing under vertical traction, a number of slings have been tested in a U lift configuration. The results again confirm that the values provided in tables from the manufacturers fail to meet the safety factor required for steel slings. This factor will also be lower for a U lift configuration than when testing with vertical traction.

The investigation has revealed that the description of the usage range given in the user manual for the steel sling is deficient.

On this basis, the PSA has requested that manufacturers, importers and suppliers of flat-braided steel slings review their products in order to assure themselves that the slings put on sale comply with the requirements specified in the machinery regulations. This means that the user manuals accompanying the slings must contain the information required to ensure prudent use.

The PSA has also requested that manufacturers, importers and suppliers contact those of their customers who have received this type of sling in order to prevent the use of slings with and inadequate built-in safety factor in relation to the load to be lifted.