Thursday, January 13, 2011


Galvanic Corrosion Thoughts…To avoid or reduce wastage -

Thoroughly and carefully coat or paint metals especially in galvanic cells.

If a coating is used, then use it on the cathode (the metal which is not going to corrode) because coating the zinc anodes will reduce their surface area. Reduce the area of the cathode not the anode.

If dissimilar metals are causing unwanted corrosion – then one or more of the following should be done –

Electrically isolate dissimilar metals.

Select metals that are close to each other on the galvanic series.

Change the potential between metals (anodes – impressed current systems).

Properly wire vessels to ABYC standards – no ground and neutral lines connected.

Use galvanic isolator – transformer.

Anode Selection

Zinc – Salt Water (make sure to use Military Spec M 18001J zinc anodes).

Activated Aluminum – an alternative to zinc in sea or brackish waters. Both zinc and activated aluminum do not work well in fresh water unless cleaned monthly.

Magnesium – Freshwater, potential excessive protection in seawater (short life).

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