Skip to content

Offshore tank container rigging failure

A member has reported two incidents in which the rigging of an offshore tank container failed as a result of a cold fracture. In both cases a tank container was rearranged on deck and damage was observed prior to actually lifting the container. There was no other damage than to the link itself.

An approved offshore container is outfitted with an associated rigging set that stays attached for handling. The container and sling are re-certified on an annual basis. For both sets of failed rigging the certification was found to be in order.

  • Both containers were lifted in static conditions (deck to deck) in good weather conditions;
  • Both containers were full at the time of lifting and the weight of the container did not exceed the safe working load;
  • There was no deformation in the link or chain observed in either case; they were so-called cold fractures;
  • In both cases it was the master link in a corner fitting of the container that failed.

Following the first incident, the chain link was sent to a laboratory to establish the cause of the failure. It was, at the time, concluded that the most likely scenario that caused the fast sudden fracture was a forging defect in the master link.

Following the second incident some seven months later, the similarities between the two incidents were apparen’t and it was established that both rigging sets were purchased from a single batch. With reference to similar incidents in the industry, hydrogen induced cracking or manufacturing process errors could not be ruled out. As this failure mechanism could not be determined by non-destructive examination methods, it was decided to replace all rigging sets from this batch (32 of) with new rigging sets.

Laboratory results are awaited on these quarantined rigging sets and the broken link for further action as appropriate.

Failed chain link
Failed chain link
Failed chain link
Failed chain link
Failed chain link
Failed chain link
Failed chain link
Failed chain link

Safety Event

Published: 1 November 2011
Download: IMCA SF 12/11

IMCA Safety Flashes
Submit a Report

IMCA Safety Flashes summarise key safety matters and incidents, allowing lessons to be more easily learnt for the benefit of all. The effectiveness of the IMCA Safety Flash system depends on Members sharing information and so avoiding repeat incidents. Please consider adding [email protected] to your internal distribution list for safety alerts or manually submitting information on incidents you consider may be relevant. All information is anonymised or sanitised, as appropriate.

IMCA’s store terms and conditions ( apply to all downloads from IMCA’s website, including this document.

IMCA makes every effort to ensure the accuracy and reliability of the data contained in the documents it publishes, but IMCA shall 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.