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Galvanically Speaking

M

Mulletwagon

Regular Contributor
The brass fittings that hold the pencil zincs on my heatexchangers and the associated bungs are showing accelerated external galvaniccorrosion. Is this because the exchangers are not grounded ? Would attaching a ground to the fittings slow(or increase) the corrosion ? Anyoneelse have this problem ?
FL Panhandle

 
You can allways add ground wires directly the the battery neg terminal on the battery to arrest electrolosis. Ground and negative earth are two different things. Electricity flows from neg to posative basically whats happening the water going out is slightly charged from negative earth is the water your floating on. You can arrest that voltage difference by adding ground wires from the battery to both of the risers going out if it is a V-8. It wouldnt hurt to add a ground to the raw water pump on the in side.
 
are you certain the source of the corrosion is what you think.....as a rule, you need an electrolyte between the dissimilar metals....
 
makomark said:
are you certain the source of the corrosion is what you think.....as a rule, you need an electrolyte between the dissimilar metals....
Click to expand...

Don’t know. The bungwhich surrounds the zinc plug has serious white and fuzzy uglies. The corrosion is radiating outward under thepaint on the heat exchanger. Easy toclean off but really want to stop it. Would like to know the science behind what is happening.
 
I'm sure its corrosion but not necessarily galvanic in nature....

I'd suspect some weeping in the pipe plug....I usually put them in with PST or perfect seal (permatex #3), whatever is handy. I've found that the mechanical interference when it come snug is enough to keep electrical contact so the zinc does its job while keeping the brine from leaking out...one of the few instances where I deviate from the manual....

as far as exactly what's going on...I'd suggest finding a good inorganic chemist.....
 
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