IMCA has issued new Safety Flash including lessons learned from incidents related to equipment failure. One case refers to an incident in which a chain parted during the recovery of a hyperbaric lifeboat (HLB) during routine testing and maintenance.
On recovery of the HLB the vessel crane started the lift and when the weight on the crane load readout was approximately 7 tonnes, one leg of the chain set parted when two links split through their link ends. Since the HLB had not yet been fully lifted out of the water the drop was minimal and the parted chain dropped back onto the top of the HLB. There was no damage to the HLB shell due to the soft covering over the chain links.
The investigation noted the following:
- Periodic inspections of the chain were in date and on record;
- Significant corrosion was discovered on the chain, raising concern about the pass/fail criteria used on the
previous visual inspection; - The cross section of the failure locations revealed corrosion indicating the presence of cracks prior to failure;
- The protective covering is a potential obstruction to thorough and effective inspection of the individual chain
links; - Environmental conditions at the time of the incident were stable and could not have contributed to high impact
loads; - The chain set has been returned to the manufacturer for mechanical testing and analysis. The results of this
testing are pending.
The operator took the following immediate corrective actions:
- Stopped the job;
- Lifted the HLB back in its original position using the davit system;
- The chain set was removed and quarantined
The following remedial actions were suggested :
- All HLB lifting chain sets should be re-inspected by full removal of the protective covering to gain complete
access to each link for a thorough visual inspection; - The inspection should be conducted by an authorised authority against an acceptable industry standard of
acceptance criteria with emphasis on wear, cracks, pitting and corrosion.
NB Further remedial actions pending the outcome of the manufacturer’s investigation may be available in due
course.
Source & Image Credit: IMCA Safety Flash
