Use of Stainless Steel Bolt onto the Galvanized Base Plate

Galvanic and Corrosion Compatibility Dissimilar Metal Corrosion

In most environments, stainless steel and galvanising won't suffer much additional corrosion due to them being in contact. It would be the galvanising that suffers if at all.

For corrosive environments (starting from marine environments upwards), the galvanising may suffer substantial additional corrosion and protective measures may be required depending on the life expectancy and usage of the object.

So if your situation is a simple factory situation (i.e. no corrosion around) or an inland rural or industrial situation, then the galvanising shouldn't be harmed and you would see it during the yearly inspection if it were to start rusting through.

A good standard I have used quite often is BS PD 6484:1979 Commentary on Corrosion at Bimetallic Contacts and its Alleviation. It is simple to use which is helpful in itself. You might be able to find it on the web somewhere.

This site was useful too for getting other articles: http://explorer.cekli.com/articles/pdf/bimetallic-corrosion