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Monday, March 18, 2019 

According to Hydrex, retrofitting scrubbers ready for the 2020 fuel sulphur regulations will usually involve drydocking to install sea chests.

Often however, going to drydock is not an option, if the scrubber equipment is not available yet during docking or if the scrubber system needs to be installed before the next scheduled docking.

Hydrex is able to carry out the installation of sea chests with the vessel stays and in some cases during cargo operations, depending on the ship’s schedule. This was demonstrated by a recent project involving installation of sea chests on two sister vessels. The Hydrex team installed overboard discharge boxes in the hull plating of these tankers during stops in Rijeka, Croatia. The same procedure was followed on both occasions.

First the double bottom tank had to be declared gas free. Once this was done Hydrex divers installed a cofferdam on the outside of the hull. The tailor-made cofferdam was designed and constructed by the company’s R&D department. The exact measurements of the area where the sea chest was to be installed were taken in advance. This was done to be sure the cofferdam would fit perfectly over the rounded shape of the hull.

The team cropped an opening in the shell plating where the sea chest needed to be installed. Hydrex certified welders then installed the sides of the box. Next the discharge pipe and valve were connected to the side of the box and the top of the chest was fitted. This concluded the interior part of the operation.

The cofferdam was then removed and an inlet/outlet grid was installed in the hull. This can also be done from the inside, before closing the sea chest if required.

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