The transit flap of a 225-meter drill ship in Dakar came loose and started swinging dangerously. This caused damage in the aft bulkhead and a leak in the ballast tank situated behind the moonpool hull. A fast solution was needed to prevent further damage.

Hydrex mobilized a team of diver/technicians. After an inspection of the damage, they disconnected the transit flap. It was then brought to shore, cut in three pieces and taken away. The divers also took all the measurements needed to design a repair plan for the second phase. Because of the instable condition of the flap, it was essential to keep to the highest safety standards, especially during this first part of the operation.

The second part of the operation consisted of the installation of six doubler plates over the damaged areas in the aft bulkhead. Constructed with the exact measurements taken during a detailed inspection, they were positioned and secured underwater by our certified diver/welders. All water was then emptied from the damaged ballast tank. The crew performed an inspection of the tank and confirmed that the compromised hull was once again fully sealed.

Thanks to the installation of the doubler plates the ship could safely start its contract. A permanent solution can now be planned at a more opportune time.

This case study is part of a larger article on underwater welding repairs, including a brief history and additional case studies.