During any lifting operation, either from a supply vessel to the installation or from within the installation or plant itself, there is a potential risk when objects are being lifted for a dropped object accident to occur.
Some of the cases wherein large objects may be dropped during lifting operations are:
1. Construction, onshore, inshore or offshore, where large objects may be lifted over hydrocarbon equipment or piping and elevated structures holding hydrocarbon equipment / piping;
2. Offshore installation, where large integrated decks or topsides modules may be lifted into place by crane barges;
3. Unloading containers and drilling equipment from supply boats and back-loading waste skips etc using the platform cranes;
4. Transferring drill pipes, casing, conductors etc. from the pipe rack to the derrick and in to the well and back using the derrick draw-works;
5. Changing out BOPs and Xmas trees during drilling, completion and work over activities using the derrick draw-works;
6. Rigging up derricks for drilling or work over activities on wellhead platforms, using the crane from a drilling tender;
7. Replacing machinery or valves for breakdown maintenance;
8. Routine movements of loads around the platform using the platform cranes;
9. Mechanical failure of lifting components, boom lines or slings;
10. Failure of crane systems (e.g. electrical, hydraulic, pneumatic, braking system etc.);
11. Structural failures (e.g. Pad eyes, crane pedestal);
12. Use of non-certified lifting equipment;
13. Inappropriate/ Inadequate procedures;
14. Inadequate communication with crane operator during operations;
15. High winds and/or supply vessel motions increasing the likelihood of accidents during supply boat offload and loading operations;
16. Human error.
If the loads are accidentally dropped, the impacts may include:
1. Injuries or fatalities among personnel underneath. These are normally covered under the Occupational Risk in the QRA studies;
2. Damage to equipment containing hydrocarbons, either on the platform or on the seabed near it. This may result in hydrocarbon leaks or, in extreme cases, blowouts. The risks of this may be used to decide whether equipment needs to be isolated and depressurized.
3. Damage to the platform structure as a whole. This is particularly important for buoyant structures, which may sink after being punctured by dropped objects.
Subsea pipelines or facilities need protection from hazards due to dropped objects which may fall from a platform, crane or drilling vessel. The dropped objects are a potential hazard where the lifting activity is frequent, especially near the platform crane or in a shipping corridor with heavy traffic. These objects dropped onto a non-buried subsea pipeline may cause indentation, crack, rupture or even crushing of the pipeline. It is therefore important to analyze the effect of such potential during the design of subsea pipelines or facilities.
A Dropped Object & Swinging Load Analysis table shall be prepared for all identified hazards.