Coatings for carbon fasteners 1

[jaydigs]

I was wondering if anyone could recommend a spray coating I could use to protect Grade 8 carbon steel fasteners that will be installed in an indoor swimming pool? I'm aware of the issues surrounding chloramines and their effects on typical stainless steels, but the Duplex and 6%Mo alloys are cost prohibitive for this application. I've found several paints that seem perfect for structural members, and plenty of rust inhibitors sold at popular industrial supply companies, but I don't have any experience with these in this type of application. If anyone could recommend a product they think would be useful I would greatly appreciate it. Thanks in advance.

 

[CoryPad]

The best coatings probably would be multilayer fluorocarbon coatings like Xylan.

Having said that, this is a terrible idea. Imperfections always exist, which can lead to localized attack, which can lead to premature failure. It would be better for you to use lower strength fasteners (coated) that are less susceptible to stress-corrosion cracking, hydrogen-assisted stress cracking, etc.

 

[jaydigs]

Thanks for the quick reply CoryPad. You think lower strength than the Grade 8? Grade 8 is our company standard although it's overkill. Maybe a Grade 2 or 5? Our fasteners are Zinc plated but I was concerned about the imperfections or abrasions that could remove the Zn and invite corrosion as you mentioned. Thanks again.

 

[CoryPad]

I recommend Grade 5. Electroplated zinc by itself will not be sufficient - you will need a high-quality topcoat for improved corrosion resistance.

 

[jaydigs]

Good deal, thanks for your help.