The whole "dissimilar metals" thing is confusing. Can someone tell me if galvanized steel and brass can be intermingled?

Im hooking up a water heater and I need a "close nipple" to make the connection between the brass fitting on the heater and the supply line which is braided stainless with a brass fitting. Can I slap a $1 galvanized nipple in there or do I need to use the $6 brass nip?

This, you could use galvanized, but brass would be preferable.

Look up galvanic corrosion. Dissimilar metals when they have water through them, the less noble metal will actually get eaten or sacrificed by the more noble metal.

Use brass.

You should stick with the same kind of metal...

That being said.

It's a water heater. They live typically 9 years. That nipple will last longer.

[batman] Do it [/batman]

thumperfbc, please check your email

quote:

Originally posted by sjp:
thumperfbc, please check your email

You've got a reply, sir. Sorry for the delay.

Regarding the plumbing.... I figured after dropping $1000 on the tankless water heater and several hundred on new 1" gas line and the various water lines to move the plumbing a little that another $6 in parts wasn't worth stressing about, so I got the brass.

When I disconnected the old tank heater I discovered that whoever put in the last unit (we've been here about 9 years and this is the first time I've dealt with the WH) used copper corrugated flex lines to connect the tank to the supply pipe. Both the pipe in the tank
And the pipe in the wall are/were galvanized. The wall pipe has SIGNIFICANT corrosion inside and out. I was afraid it would break while I was wrenching on it, but it held.

For now I cleaned up the threads with a small wire disc on my drill and it's good, no leaks, but should I plan on removing the bad pipe and just screwing a new one in? It should be threaded into a joint of some kind right behind the drywall, correct? That would make it very easy to just thread it out, go buy s new galv nipple the same length, and put it in there, right?

If it's heavily corroded, I would change it. It's a heck of a lot easier to change it before it fails than deal with a major water leak and have to change it anyways.

As the experts would say

Galvanic corrosion is caused by self-induced current created by electrical potential of two dissimilar metals in contact with an electrolyte. It can occur when two dissimilar metals (such as copper tube and steel pipe) are connected in the presence of an electrolyte. Fresh potable water is a weak electrolyte.

In 2001, I installed a sweat 3/4F x ½"M tee on a cold water header in my basement. The ½" male was plugged for future use, but I didn't have a brass plug so "temporarily" used a galvanized plug. Within a few years it was dripping. When I finally shut off the water to remove the plug, in 2016, there was nothing to unscrew. The top of the plug literally sheared off, leaving the cavity of the tee filled with the decomposed remains of the threaded portion. Which I had to dig out from an awkward angle. And flush from the line, so as not to foul up the laundry tub faucet or the washing machine sediment filters.

A total flubbard I made of it. To save a couple bucks. And this is what I profess to do for a living.

Good luck with your project!

quote:

Originally posted by Woodman:
As the experts would say

Galvanic corrosion is caused by self-induced current created by electrical potential of two dissimilar metals in contact with an electrolyte. It can occur when two dissimilar metals (such as copper tube and steel pipe) are connected in the presence of an electrolyte. Fresh potable water is a weak electrolyte.

In 2001, I installed a sweat 3/4F x ½"M tee on a cold water header in my basement. The ½" male was plugged for future use, but I didn't have a brass plug so "temporarily" used a galvanized plug. Within a few years it was dripping. When I finally shut off the water to remove the plug, in 2016, there was nothing to unscrew. The top of the plug literally sheared off, leaving the cavity of the tee filled with the decomposed remains of the threaded portion. Which I had to dig out from an awkward angle. And flush from the line, so as not to foul up the laundry tub faucet or the washing machine sediment filters.

A total flubbard I made of it. To save a couple bucks. And this is what I profess to do for a living.

Good luck with your project!

I can't really see in the wall to confirm but there should be some sort of fitting right behind the drywall where the pipe enters, right? It should be as easy as using the pipe wrench to spin the bad pipe out and then secure a new one in? The copper flex line has been replaced with a stainless line so I think I should be good there.

Am I correct in assuming the corrosion will be worst where the incorrect junction was made and that the rest of the hot water pipes aren't necessarily as bad?

quote:

Originally posted by thumperfbc:

quote:

Originally posted by Woodman:
As the experts would say

Galvanic corrosion is caused by self-induced current created by electrical potential of two dissimilar metals in contact with an electrolyte. It can occur when two dissimilar metals (such as copper tube and steel pipe) are connected in the presence of an electrolyte. Fresh potable water is a weak electrolyte.

In 2001, I installed a sweat 3/4F x ½"M tee on a cold water header in my basement. The ½" male was plugged for future use, but I didn't have a brass plug so "temporarily" used a galvanized plug. Within a few years it was dripping. When I finally shut off the water to remove the plug, in 2016, there was nothing to unscrew. The top of the plug literally sheared off, leaving the cavity of the tee filled with the decomposed remains of the threaded portion. Which I had to dig out from an awkward angle. And flush from the line, so as not to foul up the laundry tub faucet or the washing machine sediment filters.

A total flubbard I made of it. To save a couple bucks. And this is what I profess to do for a living.

Good luck with your project!

I can't really see in the wall to confirm but there should be some sort of fitting right behind the drywall where the pipe enters, right? It should be as easy as using the pipe wrench to spin the bad pipe out and then secure a new one in? The copper flex line has been replaced with a stainless line so I think I should be good there.

Am I correct in assuming the corrosion will be worst where the incorrect junction was made and that the rest of the hot water pipes aren't necessarily as bad?

It's too hard to say. You could either poke a larger hole in the drywall or buy a cheap borescope camera at harbor freight to look in the walls. At this point your best bet would be to hire a licensed plumber most likely.

The Woodman thinks your entire house is either all galvanized or more likely, a combination of copper and galvanized. Perhaps a little PEX thrown in for good measure. I'd not touch the nipple thru the wall, for now.

How about shooting me a picture of the water service entering the building, the meter, and the pipe leading to the water distribution piping for the house? I can catch all three at my house. ¾" copper coming in, a standard ⅝" meter, then I switched to 1" for the cold water header thru the house, for no particular reason.

I've done plumbing just a few miles to the east, in ranchers for ranchers. Galvanized was the pipe of the 1950s homes. And that last pic you emailed? Looks, smells, and bet it tastes like 1950s galvanized.

Not sure. I just ran copper tube and used two of those dielectric unions.

quote:

Originally posted by Woodman:
The Woodman thinks your entire house is either all galvanized or more likely, a combination of copper and galvanized. Perhaps a little PEX thrown in for good measure. I'd not touch the nipple thru the wall, for now.

How about shooting me a picture of the water service entering the building, the meter, and the pipe leading to the water distribution piping for the house? I can catch all three at my house. ¾" copper coming in, a standard ⅝" meter, then I switched to 1" for the cold water header thru the house, for no particular reason.

I've done plumbing just a few miles to the east, in ranchers for ranchers. Galvanized was the pipe of the 1950s homes. And that last pic you emailed? Looks, smells, and bet it tastes like 1950s galvanized.

It appears that most of the pipes are in fact copper. The reason I dove into this is the old water heater (in the garage) sprung a leak that we didn't catch until mold started showing up on the other side of the wall in our living space. The pedestal the heater was on was soaked and moldy, so after I installed the tankless (I put in 1" gas lines to accomdate it) I tore out the old tank pedestal and was able to get a look in the wall. I'll post pictures if Photobucket lets me.

So, prior to this project I had no plumbing knowledge but I learned enough to get the gas line pipes in and the tankless installed and working (surprised myself with that one.... the venting wasn't fun). It looks like I get to learn about drywall patching next.

Oh, the house was built in 1984. No pictures handy right now but I'm pretty sure the pipevat the meter is galvanized and I KNOW the pipe where it enters the house (where the shut off is) is also galvanized but the pipes in the wall are copper.

So, here is the pedestal the old tank heater was on before I deconstructed it:



Here it is after I removed the pedestal and a little drywall on either side. It looks like the water didn't travel to the right but it did left. Will have to open up more wall. Note the copper pipes.


Here is the corroded hot water line that was connected to the heater output by a corrugated copper line. I'd like to change this if I can.


And finally, this is the cold water supply line... where should the other end of this ground wire be attached? It apparently hasn't been attached to anything since at least 2009 when we bought the house.

A couple of those risers and T look REALLY bad in the pics. If you slide the decorative chrome wall plate back (where the pipe goes into the wall) you should be able to see if they're threaded into copper there. I think you should call a professional plumber at this time.

Also, there are some risers for sale in various places marked CHINA on them that are JUNK. They're a pinkish/reddish hue and total garbage steer clear of them. Real brass should be a yellowish/goldish hue. Here is a pic of a 6 month old Chinese riser that failed on a yacht I manage. The pump, pumps 1200 gph or salt water through 6 air conditioning units to cool off the condensing heat and could have flooded or sunk the yacht or at the very least shorted out the $1100 air conditioning pump. I noticed it because I was in that bilge doing something else, and saw a coffee pot drip from it. So a 2 hour job for a $10 riser. I hate anything made in China!!!!!!! BUT, this is a good example of what galvanic corrossion will do. Note how clean everything looks on the exterior- the pump, the riser, even the hose clamps.

Wow, what a project you have on your hands.

You should be able to spin the galv nipple out but you may want to know what it is screwed into first. And possibly hold back on it as the nipple is being unscrewed.

It may seem like the worse that can happen is that the galvanized nipple could break off in the copper or brass fitting, but the worse that can happen is that brittle solder joints further up the line will be compromised.

Tread with caution, my friend.

What you ground to is going to depend on what's available. If your house is wired with BX, you can ground the plumbing to the nearest junction box. If the wiring is Romex you will have to run the ground back to your grounding point or maybe a sewer line. I had a similar problem and went through two water heaters before I figured out that my piping was not grounded for dielectric current.

As to that nipple, I would open the wall so I could hold back on that fitting. I've had several nipples snap off on me while I was shutting an under sink stop valve because the threads rotted from the inside out.

Also, you neet to take a look at the copper pipes for corrosion. If you see bright blue/green or pink spots on the pipes you need to replace those sections because that's trouble waiting to happen.

And yes, use a brass nipple. Galvanized pipe belongs on a farm, not in a house.

quote:

Originally posted by Woodman:
Wow, what a project you have on your hands.

You should be able to spin the galv nipple out but you may want to know what it is screwed into first. And possibly hold back on it as the nipple is being unscrewed.

It may seem like the worse that can happen is that the galvanized nipple could break off in the copper or brass fitting, but the worse that can happen is that brittle solder joints further up the line will be compromised.

Tread with caution, my friend.

I agree, you HAVE to secure whatever the nipple is screwed into inside the wall so you don't snap the female end inside of the wall off, or you'll have an even bigger problem.