As part of its Safety Flashes, IMCA describes a fall of a part weighing 8.5kg over 15m from a pipelay tower to deck, while the tensioner pads were being changed out on a Tiltable Lay System (TLS). Investigation showed the change-out of tensioner pads was considered a routine task and did not require a designated Lift Plan.
The discarded pads were packed into two dedicated tensioner pad baskets on the TLS tower for transfer back to deck. The crane operator lifted a first basket and placed it in the landing zone on deck.
When lifting the second basket, a higher boom angle was needed in order to clear the TLS. As the basket cleared the TLS, it started swaying.
This movement was amplified after the basket hit the crane boom, causing a single tensioner pad to fall from the basket down to the main deck.
The displaced tensioner pad fell approximately 15 to 18 meters. There was no-one in the area at the time, and the area of the crane lift path had been barriered off as an exclusion zone.
-The dropped object (tensioner pad) resulted from the excessive movement of an unsecured load;
-The change-out of tensioner pads was considered a “routine lift” and did not require a designated Lift Plan (with a specific slew path identified);
-The operation took place at night and the sea conditions were not apparent to the crane operator or banksman when they started the lift;
- Although a risk assessment for routine lifts had been reviewed at the Toolbox Talk (TBT), the risk assessment specific to tensioner pad change-out (which includes the lifting of the baskets) was not reviewed before starting the task;
- The risk assessment specific to the tensioner pad changeout was inadequate – it did not specify a cover for the tensioner basket, nor did it take into account the effect of the sea state/swell on the swing of the load and how this should be factored into the chosen slew path;
- The locking mechanism on the side door of the tensioner pad basket was found to be inadequate and could have quite easily sprung open.
- An alternate slew path with a high boom angle would have avoided the basket striking the crane and cause increased swing;
- A cover or net fitted to the basket would have prevented the pad being displaced.
- Check all lifting appliances, supports and baskets to ensure they are fit for purpose including that doors have secure locking mechanisms;
- Never overfill and always secure the load in open top containers;
- Crane operators and banksman should work together to identify the best possible routes for moving equipment around the vessel taking sea state/swell into consideration;
- The vessel bridge should always be consulted before starting lifting operations, to ensure the sea state and vessel movements are within limits and where practical a heading to reduce vessel movement is taken.