The Wolfson Centre for Bulk Solids Handling Technology

Hydrex repairs bulker scrubber overboard pipe

(Posted on 06/07/20)

Last month Hydrex diver/technicians carried out scrubber overboard pipe repairs in Belgium and the Netherlands. In Flushing the corroded overboard pipe of a 229-meter bulker was replaced. In Antwerp the same was done on a 200-meter roro vessel. In both cases the new pipe was protected with Ecospeed, a chemical resistant coating produced by Subsea Industries.

Exhaust scrubbers are systems that filter out all harmful toxins from exhaust gasses of marine diesel engines. These can severely corrode the pipes of the scrubber which can result in water ingress if not handled quickly enough.

A small team traveled to the location of the bulker to perform an inspection of the damaged pipe on both the waterside and the onboard side of the hull. This confirmed that the scrubber outlet was corroded. Replacing the affected part of the pipe in its entirety was the only option.

A cofferdam had been constructed at the Hydrex workshop based on the drawings sent by the customer. The team installed this cofferdam over the outlet of the pipe. This allowed them to perform work inside the engine room without water ingress.

Next the team cut away the old pipe. The shell plating was then prepared for the installation of the replacement part. The new pipe had also been constructed at the Hydrex warehouse in Antwerp with a diffuser and flange already in place. The pipe was then positioned and secured with a full penetration weld. Next and independent inspector carried out NDT testing of the welding work.

To prevent the new pipe from corroding, the inside was coated with Ecospeed. This product is produced by Hydrex sister company Subsea Industries. www.subind.net. Ecospeed is highly chemically resistant. Taking into account the nature of the process taking place inside a scrubber, this is essential for a lasting protection of the pipe. Ecospeed can also be used to protect a newly installed scrubber system from day one.

The same procedure was followed on the corroded starboard overboard scrubber pipe of the roro vessel in Antwerp. The portside overboard pipe of this vessel had been replaced eight months ago and had also been coated with Ecospeed at that point. An inspection of the portside pipe revealed that the pipe and the Ecospeed coating were still in perfect condition. No further action was needed for this pipe.