Parting of slings causing fall of heavy object onto seabed

  • Safety Flash
  • Published on 18 September 2006
  • Generated on 3 April 2025
  • IMCA SF 11/06
  • 2 minute read

A diving support vessel was installing a 24 tonne metallic cover onto a subsea valve. 

What happened?

When this large object was deployed over the side of the vessel into the water, the four 15 tonne round slings used in the rigging arrangement parted and the object fell into the seabed. There were no injuries or damage to equipment or seabed infrastructure as, in accordance with the company’s procedures, the lift was made over a seabed area free of any field infrastructure.

24 tonne metallic cover

Our Member’s investigation revealed the following:

Investigation revealed that the four round slings obtained from a local supplier had been modified incorrectly and without due authorisation from the original manufacturer.

  • Close examination of the slings revealed that the fibre had been cut and re-spliced using numerous knots, hidden under the protective fabric (this could not have be spotted without dismantling the sling)
  • Whereas 6 metre (working length) slings had been procured from the local supplier, the manufacturer advised that the serial number on the round slings actually corresponded to 12 metre (working length) round slings. The manufacturer also advised that it did not fabricate 6 m (working length) round slings of 15 tonne SWL
  • There was no manufacturer certificate for the slings available from the supplier
  • The blue label showing SWL was stitched to the sling, when it normally should slide around it.
Sling
parted sling fibres
parted sling fibres
parted sling fibres

The company noted the following actions:

  • Rigging equipment shall in future only be procured from approved and recognised suppliers
  • Rigging materials are to be always subject to testing and inspection as required by the applicable international standards and company rules
  • Exceptions to the above should be subject to a rigorous and thoroughly documented management of change process covering all aspects of the rigging operation.

Latest Safety Flashes:

LTI: rope under tension moved and hit person’s hand

A member of the crew suffered a serious hand injury when struck by a rope under tension.

Read more
Injuries during lifting operations

A member reports two separate lifting activities involving failure of lifting equipment and resulting in minor injuries to nearby personnel.

Read more
Finger injury during manual handling

An IMCA’s members’ utilities supplier in the United States reports a serious finger injury during manual handling

Read more
Acetylene gas explosion

There was a small explosion and fire when crew were working on an oxy-acetylene system.

Read more
Crane cab fire caused by fridge

On a vessel alongside, there was a fire in the cab of a crane.

Read more

IMCA Safety Flashes summarise key safety matters and incidents, allowing lessons to be more easily learnt for the benefit of the entire offshore industry.

The effectiveness of the IMCA Safety Flash system depends on the industry sharing information and so avoiding repeat incidents. Incidents are classified according to IOGP's Life Saving Rules.

All information is anonymised or sanitised, as appropriate, and warnings for graphic content included where possible.

IMCA makes every effort to ensure both the accuracy and reliability of the information shared, but is not be liable for any guidance and/or recommendation and/or statement herein contained.

The information contained in this document does not fulfil or replace any individual's or Member's legal, regulatory or other duties or obligations in respect of their operations. Individuals and Members remain solely responsible for the safe, lawful and proper conduct of their operations.

Share your safety incidents with IMCA online. Sign-up to receive Safety Flashes straight to your email.