- Enter the IMCA Awards 2024: We\'re looking for outstanding Safety, Sustainability, and GHG projects.
- IP Code: Mandatory Code enters into force on 1 July. Make sure your company is up to speed with the changes.
- Early Bird tickets available for the IMCA Global Summit 2024. 3-4 December, Utrecht, Netherlands. Members can save £400.
- Discover how we are helping Members reduce emissions: Explore the ProjectGHG hub now.
- Now booking. Join the Lifting and Rigging community at our Technical Seminar in Amsterdam. Thursday 12 September 2024
- Now booking. Underwater Ship Husbandry Seminar. 10 October 2024, Singapore.
Failure during lift bag operations
A member has reported a near-miss during a lift bag operation, which highlights the dangers of inadequate safe rigging practice and of lack of awareness of actual lifting capacity of bags in relation to stated capacity.
Saturation divers were operating at seabed level at 19 metres (62ft) and had to move a 600kg (1320lb) blind flange. They had attached a lift bag, nominally rated at 500kg, to the load, so that they could manhandle it more easily into position.
At some stage during the inflation process, the diver lost control and the lift bag, with attached flange, took off towards the surface. When the bag arrived at the surface, it lost some of its volume, resulting in partial deflation. Inevitably, the load fell back to the seabed, away from the dive site, and was later recovered, undamaged.
It was fortunate that there was no harm to the divers and that the bag did not become fouled in the support vessel’s thrusters as it rose to the surface.
The company involved has noted the following key issues:
- All involved in this type of operation need to be aware that there is a potential variance between the stated capacity and actual capacity of lift bags. In this case, the actual capacity was over 25% higher than the stated capacity;
- Rigging arrangements for lift bag operations should include an ‘inverter’ line, which must be connected between the top of the bag and a fixed anchor point on the seabed. The length of the inverter line should be such that there is sufficient length to conduct the operational task, but that would it prevent the bag and load from reaching the ship or surface in the event that the bag did over-lift the load and initial control was lost. When the restraint came on, the line would cause the bag to tip, spilling some air and returning the load to safety;
- When moving long spools, for example with multiple lift bags, it should be ensured that there are adequate anchoring points for each of the inverter lines, with the anchoring positions and lengths of ‘inverter’ lines suitably calculated to ensure a safe operation.
Safety Event
Published: 1 December 2002
Download: IMCA SF 11/02
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 (https://www.imca-int.com/legal-notices/terms/) 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.