Customer's Challenge

A leading winch manufacturer required a solution to enlarge and deepen the bolt holes on a turret riser winch to increase the allowable torque capacity. This modification was necessary as per the request from the turret designer. The winch was already installed on a floating production storage and offloading (FPSO) vessel operating in Brazil’s offshore oil field, presenting several challenges. No hot work, such as welding, gas cutting, or lashing, was permitted on the vessel, making the modification process highly intricate.

The technical requirements were stringent. The bolt holes on the drum body needed to be enlarged from M36 to M42 with a running fit tolerance of Ø43mm (+0.025/0.00). Due to the horizontal orientation of the bolt holes, ensuring both perpendicularity and straightness for the new thread holes was not feasible with conventional portable tooling. Additionally, the modification required enlarging the inner pipe shaft with a precise tolerance range between 0.00mm and 0.057mm.

Solution

Metal Machines was brought in by the turret designer to devise an engineering approach that met the restrictive conditions on-site and adhered to the exacting job tolerances. To validate the feasibility of the proposed solution, the team built a 1:1 test model. This involved using a customized jig and fixture, along with a Climax BB5000 portable boring machine, for precision drilling and boring operations.

The solution and results were reviewed and approved by representatives from both the winch manufacturer and the turret designer. A test and inspection plan was created in alignment with the engineering procedure to ensure full compliance with the required specifications.

Benefits

The on-site team from Metal Machines completed the winch modification within two weeks, despite the challenging environment and strict operational constraints. By working closely with the ship’s crew, the team ensured that operations on the FPSO were not disrupted during the modification process. Through meticulous planning and repeated process reviews, the project was successfully executed and received high praise from the client for its efficiency and precision.

This comprehensive approach ensured the winch’s performance was enhanced without compromising the FPSO’s operational integrity.