OT Plumbing / copper corrosion fix - advice sought

[Mcgyver]

Awhile I ago I put in a new kitchen. The old sink had copper running up a solid brick wall and then elbowing under the counter. I decided for my drain for the install, to tie into it the copper stub with an MJ clamp and then ABS to the sink. Going down the drain is the kitchen sink and dishwasher - No chemicals other than soaps. Soft city water. Copper would have been installed in the 50's

A leak developed some time ago, very small and at the time I assumed it was a crack the pipe coming beack from the end as all I could see was a thin line beside where the MJ ended. I fixed it by clamping a piece of silicon rubber around it. I know, I'm a bad man for not doing it properly, but its horrendously awkward to get into and the wood cabinets are there so solder made me nervous. The leak came back after a while so we started putting a bowl under the leak. (Now I am a really horrible man, but its still a bloody awkward repair and I don't squirm under sinks as easily as I used to)

Very recently, like 5:00 a.m. today making coffee, it started gushing. time to face music. Pull all the ABS and garborator out so I can get in there. Was prepared to cut out the back panel if I needed to do solder.

Took a picture, wholly crow!! I have never seen a gaping hole like that in copper . The photo is directly looking up from the bottom so it looks like the area of corrosion forms a line at where the liquid would sit along the bottom of the pipe. But its soft water only, kitchen stuff is going down the drain...I thought copper was pretty bullet proof in that situation. There is the tie in to the cast iron stack but thats a ways away. Can't think of anything else that would cause galvanic corrosion.

What do you guys think, and whats the solution? First thought is to cut past the bad section and connect there with the MJ....but the corrosion has broken through there, its like;y bad all along the bottom. We're not going to be here forever and almost for sure given whats going my nice old home will knocked down...so I'm not stiffing the next guy if a do a quick and dirty repair. Still....thinking the right way is cut out the back panel, soak all the strapping with water and desolder this corroded pipe at the elbow and replace it

thoughts? ideas?

[brian Rupnow]

It looks like it may have plugged up at sometime in the past, and some well intentioned soul has put a bunch of Draino in there and left it to set overnight. that stuff will, given enough time, eat holes thru copper like that.

[Fasttrack]

Cut it back and slip a Fernco over what's left to adapt it to a PVC P-trap?

Does your dishwasher use the copper pipe as a ground connection (common in older houses when the nearest outlet is only 2-prong)?

I've seen that kind of corrosion in a few cases:

1) Galvanic corrosion
2) High pH (>8) and chlorinated water or Draino left too long (again, high pH + chloride ions)

[rickyb]

Opening is too straight for corrosion. Looking more like a seam that opened up.. yes copper is “seamless” but that’s what I looks like. Possibly a ridge or groove formed in the pipe during mfg. if so it’s limited to that piece. Cut it out and you have a good repair.

[kev74]

If this is an invitation for improper bandaids, I'm in!

You could cut out the bad part and replace it with some hose and hose clamps.

You could clean the pipe and solder a patch over the crack.

Those Flex seal commercials make me think it can fix anything!

Or you could cut it out and replace it properly.

[Mcgyver]

thanks guys....could have been drano once upon a time, except that doesn't explain why it progressed the last several years (I would hear about it and be expected do deal with a clog, which has happened...fixed via an ugly messy cleanout in the ceiling the room underneath).

Fastrack, there is nothing I've connect to the copper except the rubber MJ, an nothing I'm aware of touch it. wiring for the dishwasher comes up from the basement and is bx - in the next cabinet carcass over

[wmgeorge]

As corroded as that is un-soldering is not a option. Cut back the pipe, (saw) clean it up and slip a Fernco coupling and re-pipe to the sink with PVC or chromed brass if you wish.

[Bob Engelhardt]

Cut it off where the crack ends, so that you can inspect farther down. If it's not all rotten too, use a no-hub coupler (is that what an "MJ" is?) to connect to PVC. E.g.:
https://www.supplyhouse.com/Bluefin-...o-Hub-Coupling

If it is rotten, then do the right thing & remove it back to the elbow. Actually, it shouldn't be an elbow, but a sanitary tee for a vent. But that horse has left the barn.

[Mcgyver]

Cut it off where the crack ends, so that you can inspect farther down. If it's not all rotten too, use a no-hub coupler (is that what an "MJ" is?) to connect to PVC. E.g.:

If it is rotten, then do the right thing & remove it back to the elbow. Actually, it shouldn't be an elbow, but a sanitary tee for a vent. But that horse has left the barn.

right on. reading that twigged my brain - and I found a photo of when I had it apart. Should have thought of that earlier. You are right it ties into the vent. I really hope I'm not unsoldering at the T, it'll take a bunch heat into a closed in area where there is old wood and I can't get at If a fire starts

Everything after the MJ, my work, is ABS. I going to cut back the copper past the hole, extend the ABS to it, and MJ camp them together. Bonus, I've got enough ABS stuff in stock





This is what gets called an MJ clamp around here

[wierdscience]

Last One of those I fixed involved four wraps of inner tube rubber and four spiral hose clamps....35 years ago and it hasn't leaked a drop.

[A.K. Boomer]

I'll tell you what got the copper pipe ----------------- 70+ years is what got the copper pipe!!!

That's pretty good service so glad to see your sacking up and doing it right. lifes to short to live in a leaking stinky house...

[Dan Dubeau]

You could cut it off shorter, then desolder it at the elbow by running the torch around the inside of the pipe to keep the surrounding area flame safe using the pipe stub as a shield. Then do the same in reverse with a short stub and then solder on a copper-abs connector.

I faced almost that exact same problem about 12 years ago on our condo bathroom reno, and that's what I did. I think I even still have the extra copper-abs adapter as i bought 2 because I couldn't remember what size it was when i was at home depot and it was cheaper than a 2nd trip.

Best of luck. I hate plumbing repairs more than working on cars.

[JoeLee]

Plumbing repairs are not fun, especially under a kitchen sink. I've done a lot of soldering in close quarters and when I'm close to a wood panel I slip a piece or two of sheet metal behind the pipe.
And yeah, some drain cleaners will eventually eat through the copper. A drain pipe usually clogs in the same spot all the time so that can amount to years of drain cleaners soaking a clog in the same area.
I had a section of cast iron at a Y where the kitchen drain met the laundry room drain pipe. Had to ream it at least once a year. My father used all kinds of drain cleaner over the years.
One day when I was sending the snake down the pipe it suddenly wouldn't go any more. I pulled it out and the spring on the end was packed with brown dirt. It poked through the pipe and was burrowing into the ground. Had to cut a section out of the garage floor to repair it.

JL.................

[true temper]

Clean it up good and fiberglass it.

[J Tiers]

From the position of the hole, it does seem like something that would happen from years of the same corrosive stuff going down the pipe and sitting at that spot. Does not look right for erosion by water and grit, etc.

My surmise (not a guess, and not really an informed opinion) is that the rest of that pipe may look similar, it just has not quite been penetrated yet. Looks like you may need to cut quite a bit off. I'd do a bit at a time, until you get to sound pipe, (if you do at any place). Then use your connector and put in PVC from there up.

If there is no sound pipe, then you have a problem. I would assume that has already occurred to you.

Since you seem to have put in the pipe, the damage seems to have happened whil you have been living there. Any reasons come to mind?

I have seen drain cleaners eat up brass pipe, but have not seen copper get eaten up. Usually the zinc in the brass is eaten away, and the porous copper remnant is left. Sulfur compounds can do that to copper, though.

Gas company found that out after they installed a lot of copper service lines, using coal ash and clinker as gravel for backfill. Houses kept exploding when the pipes leaked and the gas got into the house through the hole the line went through. The clinker was both acidic, and had sulfur compounds.

..............................
I had a section of cast iron at a Y where the kitchen drain met the laundry room drain pipe. Had to ream it at least once a year. My father used all kinds of drain cleaner over the years.
One day when I was sending the snake down the pipe it suddenly wouldn't go any more. I pulled it out and the spring on the end was packed with brown dirt. It poked through the pipe and was burrowing into the ground. Had to cut a section out of the garage floor to repair it.

JL.................

We had roots like crazy. Every year they needed cleared. That happened to our pipes one time they were being "rooted". Took the guy over an hour to get the snake back out. The cutter had bounced off a big root and gone out through the ancient pipe.

We had the pipes lined after that. They had to dig up that part to remove the root mass, though. After lining, no more root problems.