Sacrificial Anodes

[Glenn]

Has anyone ever use a sacrificial anode to prevent rust?

I have seen them attached to metal pipe lines, metal couplings on plastic pipe, ships, etc, but can they be used for ironwork such as gates, railings etc?

[Frosty]

They can but they only work under the right conditions. For instance, (IIRC) if there's a dry area between the zinc anode and damp or wet iron it won't work well if at all. Using individual zincs on iron work is usually reserved for special cases like where an iron gate enters water or damp soil.

The most effective general method is galvanizing then good paint.

Frosty

[metalliferous]

Isn't the zinc from galvanization technically a sacrificial anode itself?

[Frosty]

Isn't the zinc from galvanization technically a sacrificial anode itself?

Yes it is but it differs from zinc anodes (commonly called zincs) used for things like boat hulls in that it's a complete coating where zincs are spaced at intervals below the waterline of the vessel, dock, drill platform, etc.

Zincs work best when submerged or otherwise kept constantly wet where galvy protects till it's worn or electrolized away. (I think electrolized is the, or even A, word but I suffer a general case of CRS :confused: and won't swear to it.)

Frosty

[welder19]

That is what zincs in marine applications do is prevent electrolisis which is what causes corrosion.
I don't know how it would work for rust since that is more of an oxidation issue, even stuff on boats rust but they won't get eaten away from electroisis, if the zincs are properly maintained, not oxidation.

welder19