I have a need to use a "deep" nut, preferably about 1" to 1-1/2" in depth, to receive three 5/16" size stainless steel bolts to anchor down a clean out cover on the driveway. I think the coupling nuts used for connecting threaded rods are very close to what I need. However it will be exposed to the elements so I want the coupling nuts to be stainless steel.

I went to HD and Lowes, and even though they have stainless steel bolts, they do not have stainless steel coupling nuts, they are all "Zinc Plated". Are zinc plated hardware stainless and corrosion resistant? If not where can I find what I need? I searched on the web and did see some companies that make stainless steel coupling nuts, but they sell through resellers and you can't get them unless you are ordering thousands of them. I need like 6 of them.

Thanks,

 

I googled stainless steel coupling nuts (no quotes) and came up with several retailers. I assume you'll epoxy them into a hole?

 

Yes it will be epoxied to a larger hole.