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CathFlow® antifouling system (MGPS/ICAF)

CathFlow® electrolytic antifouling supresses corrosion and prevents mussels, barnacles and similar organisms from establishing in seawater systems.

The CathFlow® system works by releasing antifoulants (ions) in the seawater, forming an environment that mitigates corrosion and discourages organisms to adhere, grow and start breeding.

CathFlow® antifouling

The CathFlow® package for antifouling treatment consists usually of control panels and anodes in seawater intakes and filter houses.

CathFlow MGPS and ICAF item package for rig

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Seawater inlet with flange anodes

Copper and aluminium/iron anodes in pair are installed in the sea chests to treat the seawater before entering the seawater piping. As the antifouling effect gradually decreases through the the piping system, complementary anodes may be required in separate dosing tanks or in mud boxes for larger seawater systems.

MGPS and ICAF mounted in in seachests to prevent fouling and corrosion
MGPS and ICAF mounted in in seachests to prevent fouling and corrosion

How to change MGPS/ICAF anodes in sewater inlet?

In dry dock the replacement is straightforward. Whilst afloat, it can be more challenging. Some modern semisubs have access to sealing covers for the sea chest gratings, which can be installed inshore by the assistance of divers. This makes it possible to release the water pressure in the sea chest, and MGPS anodes can easily be changed.

Even if the rig is not equipped with prefabricated covers, some diving companies can arrange proper sealing of the seachest on demand. Two barriers will normally be required. It is common to combine the replacement of MGPS anodes in sea chests with survey and repair of sea water direct and over board valves and piping.

Anodes in mud box

Anodes can be mounted at the strainer lids as shown in the illustration below. This arrangement will treat the water against fouling in the mud boxes and inwards the pipes

MGPS/ICAF antifouling anodes mounted at strainer lid
MGPS/ICAF antifouling anodes mounted at strainer lid

Effect of cathodic protection in pipings

It should be noted that remote installed anodes (sacrificial and antifouling anodes) located in sea chest or mud boxes, do not prevent galvanic corrosion caused by poor material quality or incorrect material combinations in the pipes. Such anodes can, however, be expected to provide local corrosion protection nearby the anodes. As rule of thumb, anodes installed in pipes can be assumed to provide cathodic protection five times the pipe diameter inward the pipe.