• Permanent underwater hull repairs keep tanker out of drydock

    Permanent underwater hull repairs keep tanker out of drydock

    14/06/2013

    Last month a Hydrex team mobilized to a 100-meter tanker vessel berthed in Rotterdam to perform underwater hull repairs. Despite the relative small scale of this operation, it was nonetheless vital for the shipowner. It allowed him to keep his vessel out of drydock and avoid having to go off hire.

    Hydrex on-site hull repair services include the renewal of both small and large areas of damaged hull plating. These repairs can be carried out above or below water, according to the circumstances, with tailor-made mobdocks. Normal commercial activities can therefore continue without disruption. These operations follow the Hydrex procedure for welding cracks and inserts in the vessel's shell plating and they are approved by the major classification societies.

    Permanent insert repair in Rotterdam

    A cavitation hole needed to be repaired in the bottom plating of the tanker. A Hydrex diver/technician team therefore carried out a detailed inspection of both the onboard as well as the water side of the affected plating.

    Next the team installed a cofferdam over the area.  This cofferdam was modified to fit perfectly over the rounded shape of the hull.

    This allowed them to remove the frames covering the damage. The diver/technicians could then cut away the damage and the surrounding area, including the speedlog. Next they positioned a new insert plate, measuring 500 mm x 450 mm, with a new speedlog. The insert was then secured following the Hydrex class approved procedure for insert plates, using a full penetration weld.

    An independent tester carried out ultrasonic testing and the repair was approved by the classification surveyor who was present during the operation. The diver/technicians then refitted the frames. They then removed the cofferdam, concluding the repair.

    Conclusion
    Repairs of this kind can only be done rapidly and successfully by trained divers/technicians who are familiar with the procedures and who have the relevant know-how to resolve all of the technical difficulties encountered during underwater operations. This is why all Hydrex technical staff from all offices undergo stringent training, enabling them to perform a wide range of operations. Hydrex diver/technician teams carry out these on-site hull repairs all over the world.

    Throughout this operation diver/technicians stayed in close communication with each other and with the technical department in the office. This allowed them to finish this job within the shortest possible time frame without any compromise of the high quality standards Hydrex is known for.   

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