304 with Galvanized Steel 1

[SteveWag]

For years I have specified 304/316 fasteners for use in plants treating domestic sewage, in submerged and exposed conditions, with no issues that I know of. I recently specified some galvanized clairifier arms and 304 fasteners. A co-worker pointed out to me that this may result in damage to the zinc. Does anyone have any experiance with this?

Thanks
Steve

 

[CoryPad]

thread338-29393

thread1135-197190

thread338-178957

Regards,

Cory

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

 

[rconner]

I am not going to claim expertise in nor presume to offer recommendations for this specific application; however, I sometimes wonder in reading some responses to these threads if it sometimes may be too easy to say (based on textbook knowledge of galvanic series and Faraday's law etc. only) that any dissimilar metal couple will cause meaningful failure (of course only in an environment where all the necessary elements for same are present). Maybe one could even thereby say that carbon steel will result in "damage to the zinc"??
However, is it possible that there might be some degree of (practical?) utility to galvanizing, or for that matter this specific material choice of (cathodic) material fasteners (at least if one neglects ”galling”, as some SS may be prone to do), in this or some other environments/applications? After all at least with regard to galvanizing, I happened to notice the quote at

http://en.wikipedia.org/wiki/Galvanization,

“Hot-dip galvanized steel has been effectively used for more than 150 years” (and then there may be the apparent “no news is good news” experience of the present inquirer in this application).
Now if one were to on the other hand choose (a small area of) highly stressed (anodic) carbon steel fasteners to join a large area of (e.g. stainless) steel plates, that is another matter and I would certainly agree meaningful problems might well rather quickly ensue!