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Monday, August 16, 2021 

Underwater repair specialist Hydrex has recently carried out temporary repairs to three corroded scrubber overboard pipes of a 292m long bulk carrier, which was prevented from sailing from Ijmuiden in the Netherlands to a drydock unless a temporary repair could be made.

Harmful toxins in the output of exhaust gas cleaning systems can severely corrode the outlet pipes and result in water ingress. For this reason the classification society requires thickness measurements to be performed on a regular basis. An inspection revealed that the three pipes were heavily corroded and needed to be repaired. The ship was sailing to drydock where the pipes would be replaced, so a fast temporary solution was required.

A Hydrex  team travelled to Ijmuiden and inspected the damaged areas on both the waterside and the onboard side of the hull. Diver/welders then sealed off the outlets of the overboard pipes with custom cofferdams designed and constructed at the Hydrex workshop. This allowed for work inside the engine room without water ingress.

The team ground away the affected area before rebuilding it back to its original thickness. To give extra protection during the trip to drydock they installed reinforcement shells around the pipes. When the welding was complete the surface was cleaned and an MPI was carried out by an independent inspector.

The inside of the pipes was then coated with Ecospeed, a chemically-resistant coating produced by Hydrex sister company Subsea Industries. Ecospeed will be used to coat the replacement pipes before they are installed in drydock to avoid a recurrence of the problem.

In this case a drydock visit had already been planned and a temporary repair was needed, but Hydrex teams can also replace a corroded outlet pipe as a permanent repair while the vessel stays afloat. Hydrex can replace pipes as a preventive measure before severe corrosion sets in, thus avoiding costly unscheduled repairs.

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