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Zinc Plated carbon steel (gr 8) bolts to 304 sst

I am mounting a SST HVAC unit with Zinc plated carbon steel bolts. The unit will be mounted on top of a transit vehicle and will be expose to the outdoor environment. Grade 8 bolts are required for the isolation mounts. Does anyone know of a barrier that could be applied between the two dissimilar metals to prevent galvanic corrosion? My customer does not want to use a neoprene pad because of the potential for the neoprene to relax causing the bolts to loosen. Do I really have a problem between these two metals, is there any web page or reference material I could use to investigate the actual corrosion rate? Is there another finish I could us on the bolts besides zinc?

John Caruso
Engineer - Bath, New York
2004

There shouldn't be a problem even as-is. (Too bad that cadmium plating is getting rare because it would be better; the oxide of zinc eats aluminum and cad is compatible, but I digress) Against any common stainless steel, galvanized carbon steel should be OK. Even bare. If you really want to finesse the job, make the joints wet with any primer paint in the interface.

James David Hunter
fiberoptics - Jacksonville, Florida, USA
2004