Recently Hydrex teams of diver/technicians mobilized to a 164-meter roro vessel berthed in Antwerp, Belgium and a 235-meter bulker at anchor in Punta Del Este, Uruguay to perform underwater hull repairs. Despite the smaller scale of these operations they are nonetheless vital for shipowners if they want to avoid unscheduled drydock visits for their vessels.
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.
Hydrex diver/technician teams carry out these on-site hull repairs all over the world. In most cases the damaged area can be replaced with a permanent insert and no condition of class is imposed. On the rare occasions where the damage does not allow such a repair, as was the case in Uruguay, a temporary doubler plate is installed over the affected area. This allows the owners to keep to their schedule and have a permanent repair carried out during the next scheduled drydock visit.
Permanent insert repair in Antwerp
A cavitation hole needed to be repaired in the shell plating of a 164-meter roro during the ship’s stop in Antwerp. A Hydrex diver/technician team therefore carried out a detailed inspection of both the onboard as well as the water side of the shell plating, after which they installed a cofferdam over the affected area.
This allowed them to remove the frame covering the damage and cut away a round area with a diameter of 300 mm. Next they positioned a new insert plate of the same dimensions and secured it with a full penetration weld. An independent tester then carried out ultrasonic testing and the repair was approved by the Lloyd’s Register surveyor who was present during the operation. The diver/technicians then reinstalled the frame and removed the cofferdam, concluding the repair.
Afloat doubler plate installation in Uruguay
Hydrex was contacted to install a doubler plate over a grounding related crack located on the flat bottom area of the first port side ballast tank of a 235-meter bulker in Punta Del Este. After arriving in Uruguay, a diver/technician team set up a workstation on a workboat and sailed to the location of the vessel.
A detailed inspection revealed that the L-shaped crack was 480-mm long and between 4 and 8 mm wide. In the area of impact, a 250-mm deep and 25-meter long indent was also found. In the ballast tank, the team then removed the frames that had bent during the grounding. This allowed the diver/technicians to access the damage and make crack arrests on both sides to prevent the crack from spreading further. The team then installed a doubler plate over the crack on the water side as well as the in board side. The vessel could sail safely until the next scheduled drydocking where permanent repairs will be carried out.
Repairs of this kind can only be done rapidly and successfully by trained divers/technicians who are familiar with them 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 after which they are able to perform a wide range of operations. Throughout these operations they stayed in close communication with each other and with the technical department in the office. This allowed them to finish these jobs within the shortest possible time frame and this without any compromise of the high quality standards Hydrex is known for.
Press Release, October 01, 2012