IMCA Diving Division

Publication Details

Underwater Air Lift Bags

Underwater lift bags are major pieces of lifting equipment and should be treated with the respect that any such equipment warrants. This publication aims to provide clear guidance on six related topics: fitness for purpose; examination and testing criteria; maintenance; operational considerations; operational guidance; safety precautions during use.

The guidance is aimed at both closed and parachute-type bags that are used to lift submerged objects. It does not apply to water-filled bags that are used as water weights for testing other equipment.

Lift bags cannot normally lift loads that are greater than their designed safe working loads because they cannot be over-inflated. Parachute-type bags have an open bottom which spills out air when they are full, while closed bags have a relief valve. However, the rigging can be subjected to additional snatch loads in various ways, for example if the bag is incorrectly rigged. The guidance points out that these, and any other additional loads, should be accounted for in the 5:1 safety factor that is used.

Training of personnel is also addressed, and particular areas of required knowledge are highlighted that will ensure that personnel are aware of what can be accomplished and the potential dangers.

The latest (June 2007) updates reflect further experience gained in the use of underwater air lift bags, with changes to the operational guidance. Further examples of different types of lift are also included.

Contents

1. Scope
2. Objectives
3. Definitions
4. Background
5. New equipment
6. Initial and periodic examination, testing and certification
7. Operational considerations
8. Operational guidance
9. Maintenance
10. Training
11. References
12. Appendices
• Categories of competent person
• Examination, test and certification criteria
• Sample air lift bag pre-use checklist
• Sample underwater lifting bag repair checklist
• Examples of different lifting categories