304 stainless fittings mixed with galvanized fittings - OK, or not smart?

[sklett]

Hello, first post and I decided to ask my question here because I'm going in circles and driving myself absolutely crazy.

My situation: Running a 700' long, 1-1/4" 200 PSI (SIDR9) polyflex (ADS) line from shop to my house. Along the way I want to install a non-freeze yard hydrant. I planned to use 304 stainless NPT barbed adapters on the poly line and galvanized fittings for the hydrant offset and connection. Picture galvanized tee with stainless barb adapters at both ends.

On a whim I googled "Mixing stainless and galvanized fittings" and found this useful page. I understand enough of that to take away that using dissimilar metals in an electrolytic environment (damp soil) is a bad idea... or is it? Is this one of those things where an engineer would say "Well, it IS possible that corrosion can be increased" but in practice, it's really not a concern? Like if this was a nuclear plant cooling system you would care, but for my application I wouldn't notice for 150 years?

I'm hoping that wise, experienced pros will tell me not to worry about it, that my plan is fine, that they've done it for 50 years, etc. On the other hand, if it's a bad idea, I'd like to avoid learning this the hard way.

So... hopefully some of you know and can set my mind at ease with a little guidance.
Thank you for reading my long post.

-Steve

 

[Reach4]

Use brass, or stainless, or bronze tees. Why are you considering galvanized? That rusts.

 

[Sponsor]

 

[sklett]

... Why are you considering galvanized? That rusts.

Good question. I was using galvanized because my local well and pump company uses galvanized for everything and they've been in business for several decades and have a good reputation. Basically I'm copying what I've seen others do, but I agree I've seen galv rust.

The hydrant appears to have a brass valve body. If I go all stainless with my fittings is it a problem connecting to the brass valve body of the hydrant?

 

[Jeff H Young]

I'd avoid Galvanized . of course it rusts but if the water is really good and the quality of material very high it might be fine for 40 years. but I can't tell quality on Gal as far as I'm concerned if its from the last 25 years its pretty much Crap. I do like the solidness of gal it doesn't damage easy and short sections aren't hard to change out, and you can save a few bucks on material. For like a 90 and a riser coming up out of ground for a hose bib its still a good way to run I have no problem with that and feel its pretty indestructible . but for other uses I frown

 

[Reach4]

The hydrant appears to have a brass valve body. If I go all stainless with my fittings is it a problem connecting to the brass valve body of the hydrant?

Not a problem.

There can be a problem connecting stainless to stainless, and then trying to get it apart later. To read about that, try this in a search engine stainless steel galling. There are ways to make them more removable later, but in this application, I don't see disassembly as likely.

Your link for the hydrant you are using did not work.

There are things like this:

https://www.homedepot.com/p/Hydrant...tee-and-2-M67127-SS-clamps-HIKTNL75/307718895

Those connect to SIDR pipe.

 

[sklett]

Thanks all for the input. While my original question is still unanswered, I think I'll change from stainless to a more simple setup using bronze fittings like Reach4 suggested.

I like that it has that standoff so I can set a small brick under it on the hole and it will be supported.

 

[John Gayewski]

The main problem with stainless is the leaks, and 304 a can't be burried by code. Gotta be 316. Whip out the wallet.