I installed a new kitchen faucet over the weekend. In the process of putting in new supply valves I ran into some really bad corrosion - not in the old valves, but in the end of the stubout nipples. It was advanced to the degree that some of the pipe thread was gone and I only had 1 to 1-1/2 turns of engagement for the new valves. I was unable to get them on so they wouldn't drip - albeit very slowly - so I'm doing the best I can to minimize damage until a more permanent solution is in place.

Our supply lines under the house are all copper except inside the walls, where it appears to be the original (1967 build date) galvanized pipe. I'm hopeful that simply replacing the stubouts would suffice for a while, but I'm concerned about it being just one patch on a tire full of holes.

Could this be an isolated incidence of corrosion because of its proximity to a valve, or are the odds fairly high that the problem is systemic and would call for all the galvanized [in-wall] plumbing to be replaced?

If the house has galvanized and copper together, you are probably looking at a problem throughout the system.

its hard to say what condition the behind the wall piping is in ??
if the threads are gone on the inside end of the stubouts, you don't have much choice but to back them out and replace them. the ends inside the wall should be much better since they are iron to iron rather than iron to brass.

I planned to attempt that first, but the ends are basically flush with the wall so any attempt to remove the stubouts with a pipe wrench would definitely destroy what little is left of the thread. I wanted to understand my options for a contingency plan better before moving ahead.

I'm guessing the problem is systemic to a degree, but if I thought swapping out the stubouts would for sure buy me a couple years, I'd take the chance. If I thought it was just a short term (a few months or less) fix, I'd save the few bucks and the pain of possibly having to remove the garbage disposal and apply the resources to replacing as many galvanized risers as I can with high quality PEX risers.

Your response makes me think there's hope in replacing the stubouts.

Thanks!

The only galvanized should be the stub outs, so it you unscrew them and replace them with brass nipples your troubles will be over.

"High quality PEX risers"

Why not just use type-L copper instead of some Chinese plastics which probably cause cancer?

Copper is amicrobial.

Or maybe I'm just being paranoid, pros please correct me if I'm off base here.

if pex causes cancer, we are all in trouble. there must be millions of miles of pex installed throughout the world.
it is one thing to tell the people who frequent this site for advice that the tub is not installed correctly or they should not throw grease in their kitchen sink. BUT to give them the impression that they will get cancer from pex (which the vast majority of us install) is not a good idea.

As for PEX causing cancer, I don't see how it would be any worse than what's inside all our pipes already. As much as we can help it, we don't drink ANY water that comes straight out of the pipe.

"The only galvanized should be the stub outs, so it you unscrew them and replace them with brass nipples your troubles will be over."

So you're saying brass nipples will hold up better than galvanized? Wouldn't that move the galvanic potential behind the wall? It seems it would be better to have it exposed so it could be monitored.

Anybody?



Edited 1 times.

There may be brass drop eared ells behind the wall.

If they used copper under the house they probably used copper in the walls as well. The nipple coming out of the wall is probably done just as your shower arm is, copper to a brass drop ear ell and then a threaded nipple. Why would someone want to install threaded piping while copper was available and cheap?