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Monday, January 4, 2021 

Hydrex has recently carried out repairs to scrubber overboard pipe on vessels in Belgium, France, the Netherlands and Spain, including cutting out and rewelding . two scrubber pipes on a 200m ro-ro vessel and replacement of six pipes on a 400m container ship.

According to Hydrex, the harmful toxins filtered out by scrubber systems from exhaust gasses can severely corrode the scrubber pipes, resulting in water ingress if repairs are bot carried out promptly.

The company’s diver/technicians can normally carry out necessary repairs or replacements with the vessels afloat, and are able to rapidly mobilise when needed. In the case of the ro-ro, corrosion was not yet severe, a full replacement of the pipes was not needed. After sealing off the outlets of both overboard pipes, the work of grinding away the affected area and re-welding to original thickness was undertaken within the engine room.

The container ship repair was more complex, with the work carried out in stages in different locations, enabling the ship to maintain its sailing schedule. The pipes needed to be replaced completely, so new outlets were constructed at the Hydrex warehouse in Antwerp. The repair included welding to the inside hull shell plating, so it was not possible to seal the outlets in the same way. So six custom cofferdams were designed and constructed at the company’s workshop based on customer drawings sent by the customer. The team installed the cofferdams over the outlets of the pipes, allowing the welders to work safely on the shell plating. All six pipes were removed and new pipework welded into place with a full penetration weld. The seams were NDT tested by an independent inspector.

In both cases, the pipework was protected against future corrosion by the application of Ecospeed coating from Hydrex's sister company Subsea Industries.

Ecospeed has also recently been applied on the scrubber overboard pipes and surrounding areas on two oil tankers, in China and Singapore. Ecospeed is highly chemically resistant, and can last the lifetime of a vessel. As it is biocide-free there is no negative effect on the water quality or the marine environment during application or use.

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