Stainless Bolts w/Galv Steel

[JKW05]

I have an SSINA Designer Handbook that suggests "the corrosion of the base metal may be markedly increased by the fastener material" when using stainless steel bolts with galvanized steel. Anybody have any experience with this?

 

[CoryPad]

Yes. Passive stainless will promote the rapid consumption of the zinc, followed by the iron underneath it. It is best to use zinc coated fasteners (hot dipped galvanizing, zinc electroplating, or multilayer zinc flake coating) to join galvanized structures.

Regards,

Cory

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

 

[btrueblood]

It's kinda neat, though, to see the pretty zinc crystals all over your stainless hardware (this is from fully immersed hardware).

 

[JKW05]

Thank you both for your replies...

My boss doesn't seem to think this is much of a problem. I have already cited the SSINA Designer Handbook; Would you know of any other references I can use to support my position? These are for immersed applications in sewage treatment tanks.

JW

 

[corrosionman]

JKW05 I am presently replacing several circular shells, 3 feet dia made from heavily Galvanised steel , each is in two halves and joined together with 3/8 stainless bolts - they have been totally immersed in Sewage liquor and are now in such condition as to need replacement ( now being made in GRP ) The corrosion was hastened because these shells were touching the stainless supply pipe ,also submerged .Cheers CM
(do you want a picture of the shell for your boss? )

 

[SteveWag]

corrosionman, how long were these is service?

Steve

 

[JKW05]

Corrosionman,

If there is a way of obtaining a picture, that may be useful; Thanks!

Also, I would also be interested in how long these were in service.

JKW