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Underwater repairs facilitated by flexible repair methodology

Shiprepair & Maintenance: 2nd Quarter 2019Hydrex

In a recent demonstration of its capabilities, Hydrex diver/technicians carried out underwater stern tube seal repairs on a 225m bulk carrier during the vessel’s stop in Ghent. The ship’s stern tube was suffering an oil leak, making a quick on-site repair necessary.


Once the repairs were approved, the diver/technicians were dispatched to the ship with one of the company’s workboats, which have been equipped as dive support stations. During the operation the team removed the damaged seals and replaced them with new ones, using original spare parts.


Taking advantage of the Hydrex flexible mobdock technique, the team was able to carry out the entire repair in situ and underwater.


“Because all the required material is ready to be transported at all times, no time is lost making preparations,” said company spokesperson, Christophe Verhoeven. “As a result, the owner of the bulk carrier did not have to delay the ship’s schedule unnecessarily, let alone arrange a costly and unwelcome trip to drydock.”


In other recent operations, Hydrex divers carried out six stern tube seal operations in various locations across Europe, all within a very short time span. In Flushing, UK, four damaged seals on a 268m container vessel were replaced underwater using the flexible mobdock technique, while in Antwerp a seal operation was performed on a 185m general cargo ship.


“Both of these operations are good examples of how Hydrex uses its experience and know-how to offer the best solution for a specific situation,” said Verhoeven. “In the first example an underwater seal replacement using our flexible mobdock technique was the only option, but for the second vessel trimming was more efficient.”


Demonstrating the benefits of the in-house developed cofferdam technique, Hydrex carried out a pipe repair on a 238m cruise ship while at Punta Del Este, Uruguay earlier this year. The vessel was suffering a leak as a result of corrosion damage to the pipe and a swift on-site solution was suggested by the company’s technical department. The repairs were performed afloat using the Hydrex cofferdam technique, which gave the owner a cost-effective alternative to drydocking.


While preparations for the welding work were taking place inside the engine room, a mobdock was installed and secured underwater over the outlet of the damaged pipe. The Hydrex team then disconnected the old overboard pipe and the surrounding support frames as the hull plating and new piping were prepared for fitting. Once the pipe was positioned, welding to connect it to the hull was carried out according to Hydrex class approved welding procedures. The support frames were then reinstalled and the remaining piping and valve were reconnected.


Hydrex has also been called upon to install the additional sea chests required for the intakes and outlets of exhaust gas scrubbers.