CORROSION IN FERTILIZER AND SALT

[LARRYNELSON]

I need to attach non conductive rubber to large steel bars using 0.25" case hardener zinc plated screws. What material should a flat washer be to minimize corrosion with the screw head in a damp salt and fertilizer environment? The washer will only touch the rubber and the screw. Zinc plated rivets with out washers currently work successfully in this application, but they need to be replaced with the screw and washer combination. I have 409ss, 304ss and galvanized washers currently available.

 

[CoryPad]

Galvanized would be best, since it would avoid galvanic attack between the screw and washer.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[EdStainless]

I go with Cory, either use both galv, or both 409SS.
The 409 will start corroding right away, but the rate will be fairly slow.
The galv parts wil look OK until the galv is consumed or warn off, and then they will corrode quickly.
You might want to use a sealer to prevent material and moisture from getting trapped under the screw head. You could also use a dab of Zn rich primer for this sealant.

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