• Wide range of hull repairs in Europe and North America

    Wide range of hull repairs in Europe and North America

    31/08/2017

    During the last month our teams flew across Europe and the United States. to perform a wide range of hull repairs on different types of vessels. In this article we will give you a summary of some of these operations. They illustrate the diversity of shell plating operations our diver/technicians are trained for.

    Our class approved repairs combine both underwater mobdock installation and inside dry welding. Both parts of such an operation are performed by the same team of in-house trained diver/welders working at the highest technical standards.

    Our permanent welding repairs include the following operations:

    • Renewal of damaged hull plating, large or small areas
    • Crack repairs by use of mobdock
    • Pipe/flange repairs or replacements
    • Clad welding of cavitated areas
    • Inwater seachest installation
    • Installation of speed log or echo sounder housing

    These operations are carried out afloat with the use of an external mobdock. In most cases normal commercial activities can therefore continue without disruption. We have a wide range of standard mobdocks available at our offices, but a tailor-made mobdock can also be created to fit a specific hull shape or purpose. This was the case during the flat bottom plating repairs in Port of Santander, Spain and Palm Beach, United States.



    Mobdock designed to fit specific shape of hulls

    Port of Santander
    A 115-meter LPG tanker needed to have a new insert installed on a damaged section of its flat bottom. Because the vessel had just left drydock in Port of Santander when the damage was discovered, going back to dock was not a feasible option. Our technical department was contacted and asked to design and install a special mobdock. This would allow the shipyard to perform the repair underwater in drydocklike conditions while the ship was berthed outside the yard.

    A team of our diver/technicians traveled to Santander. First they performed a preliminary underwater inspection of the damage. This revealed that the required insert would be 400 x 300mm. Next they used a special frame to take the measurements needed to design the mobdock so that it would perfectly fit the rounded shape of the hull.

    The mobdock was constructed at the shipyard following the design plan provided by our R&D department. When it was finished, it was installed by our team. The shipyard could then perform the insert repair in the best possible conditions. Once the repair was finalized and approved by the representative of the classification society, our team removed the mobdock.

    The LPG tanker could continue its schedule without having to wait for a drydock space to become available, much to the satisfaction of both the owner and the shipyard that performed the repair.



    Palm Beach
    Besides designing and installing a tailor-made mobdock, our teams can also perform the actual insert repair. An excellent example of this was the operation performed in Palm Beach (U.S.A.) on a roro vessel.

    The ship suffered corrosion damage to the aft starboard side shell plating. Because the damage was situated in the turn of bilge it was again essential that the mobdock was modified to fit perfectly over the rounded shape of the hull.

    After the mobdock was installed, the frame covering the damage was removed. This allowed the team to cut away the damage and the surrounding area. A new insert plate was then positioned and welded following our class-approved procedure.

    An independent inspector carried out ultrasonic tests and the repair was approved by the classification surveyor who was present during the operation.

    Doubler plate installation on general cargo vessel and OSV

    Ostend
    On the rare occasions where the damage does not allow a permanent repair, a temporary doubler plate is installed over the affected area. This allows the owners to keep sailing until the next scheduled drydock visit when they can arrange a permanent repair.

    Such a repair was performed on an offshore supply vessel in Ostend (Belgium). A small hole situated on the starboard side of the flat bottom was covered. A minor repair like this can easily be carried out in less than a day without any interference to a ship’s schedule.

    Antwerp
    The operation required on a leaking 198-meter general cargo vessel berthed close to our main office in Antwerp was a lot less straightforward. A detailed inspection of the affected area revealed corrosion damage in the flat bottom. The inspection also showed that the shell plating surrounding the damage was not thick enough anymore for an insert repair and in poor general condition. Installing a new insert plate was therefore not an option. Our technical department proposed to install 4 large doubler plates on the inside of the hull to cover the damage and the parts of the flat bottom that were at risk.

    The plates had an average dimension of 1255 x 400 mm and were cut to size at our headquarter’s fast response center. They were then fitted and secured by our diver/technicians. To prevent any further leaks, additional welding work was performed by our team on the rest of the area.

    Detailed thickness measurements were requested by the attending classification surveyor to make sure the vessel could sail safely until the next drydock visit. As a result of our intervention the owner can now arrange this trip to drydock at a more convenient time and location.

    Conclusion
    We have the know-how and experience needed to find the best solution for any problem you might encounter with your vessel. This can be a simple routine repair or a unique complex one, as illustrated by these case studies. We can easily adapt a repair to your schedule. If required we can split up an operation and perform it in parts on different locations. Our goal is to keep you sailing with as little delay as possible.



     

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