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Q & A

Fixing Corrosion

Fixing A; Brass Roof Vents to Steel Roof.
B; Steel Hinge to Aluminium Engine Cover.
Your Advice please

Asked by: Michael Clement  | 2.57pm, Wednesday 27 April

WW says:

As your question implies, the problem is that two dissimilar metals will corrode when exposed to an electrolyte - most commonly, water. The basic answer is to try to insulate one metal from the other and stop water getting to either of them.
Separating them could be done by using a suitable insulating gasket. Thin rubber might be stuck to one side or you could use the sealer tape that is used around weed hatches to stop water getting in. If the roof is well painted, this should prevent rain from acting as an electrolyte but you might improve it further by painting the lower frame of the roof vent as well. If this is brass, you will need to use a suitable non-ferrous primer. A good marine sealant around the edge of the roof vent should ensure that water does not find its way into the gap between the two metals.
The same applies to the engine cover - separate the two metals and ensure that the hinges and part of the cover are well painted, then seal the edge.

Graham Booth  | 3.59PM, Wednesday 27 April

If ordinary silicone sealant has been used to seal the joints, this gives off acetone during curing which wil promote corrosion if applied to bare steel. Better to paint the steel well before sealing as Mark says.

Rupert Smedley  | 4.43PM, Wednesday 27 April

Readers say:

Thank you Gentlemen.

Michael Clement  | 2.10PM, Thursday 28 April

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