My house is 1920s, New England. its been upgraded and added onto a few times.

2nd floor toilet shut off was leaking.

I cut off the valve as I was unable to safely get a torch on it to un-solder it.

I shut off hot and cold water to the 2nd floor as the faucet and tub have mixing vales.

The supply ID is 1/2" so I got this 1/2 in. Nominal Compression Inlet x 3/8 in. O.D. Compression Outlet 1/4-Turn Angle Valve

To my horror, the OD of the pipe is 11/16 (maybe brass? older copper?)

As I understand, 1/2" copper is 5/8 OD so my part doesn't fit.


What part(s) do I need to button this back up?

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  • Not answer to your question but about the size, I wonder if newer pipes have thinner walls due material cost, better manufacturing etc
    – Ack
    Apr 11, 2020 at 22:37
  • Photo of the pipe cleaned up might help.
    – Alaska Man
    Apr 11, 2020 at 22:38
  • I'll try to get a photo in here, but really it's just a few inches of pipe coming out of the wall. 11/16 OD, 1/2 ID. Can't find adapters or valves to get there.
    – Zipper1365
    Apr 11, 2020 at 22:51
  • You can not get the nut and compression ferrule over the pipe ? Have you cleaned it by sanding it with emery cloth ?
    – Alaska Man
    Apr 11, 2020 at 23:04
  • @AlaskaMan exactly. Pipe OD is too big. I haven't fully cleaned it up yet wit. but it's very clearly too big. I mean I could sand it down, but I would have to remove so much, I doubt I'd be able to keep it uniform enough to trust putting a fitting on.
    – Zipper1365
    Apr 11, 2020 at 23:10

3 Answers 3


Here is what I determined after some research

Some (many) people seemed to think that this was caused by water freezing in the pipe and expanding the tubing but others debunked that because it tends to split the pipe and there would be other evidence of the freezing. I also don't believe that it was a freeze cycle.

Pipe and tubing sizes were set in the early 1900's BUT apparently Westinghouse supplied an 11/16" pipe which was more commonly installed on the west coast but can also be found throughout the country. Some plumbing supply houses carried fittings through the 1980's until they were considered obsolete and unnecessary.

The problem was solved in a couple of ways:

  1. use a swage tool to sweg it out to receive a 1/2" pipe soldered on to it
  2. have couplers made out of copper stock on a lathe
  • 1
    Thanks for looking into that a bit for me! I suspect that this bathroom was redone in the late 80s or early 90s so that explains the source of the current (now removed) valve and the lack of availability of a direct replacement. I'm going to wait a bit to accept an answer in case there are other options out there, though. I'm hoping for a more or less off the shelf solution.
    – Zipper1365
    Apr 12, 2020 at 1:12
  • 1
    I accepted your answer since it addressed the question as it was posed. however. I've since discovered that there's a lot I don't know! turns out that this was/is standard 1/2 copper that had a sleeve over it. the valve and the sleeve were a packaged deal. that's why the walls appeared thicker and that's why noting fit it to do what I wanted. I have since been able to painstaking remove the sleeve and and attach a standard compression shut off to the stub
    – Zipper1365
    Apr 30, 2020 at 2:05
  • Thanks for the answer accepted and especially for checking back in to fill in the rest of the story, that will surely help others at some point. I'm glad that it worked out
    – Ack
    Apr 30, 2020 at 3:26
  • 1
    I ran into a very similar situation yesterday. I believe I have a BrassCraft valve with a 5 inch extension (model CS41/ CS41B/ CS47) that is soldered/sweated onto a standard 5/8 OD tube. So the inner diameter of the extension tube of the valve assembly is sufficient to accommodate the outer diameter of the copper tubing. I hate soldering so I am trying to get a plumber to come out and do the repair. For the future, if I encounter a valve like this that does not turn off, I will simply put in a repair value that has 3/8 inch for both input and output. Jul 23, 2021 at 14:52
  • 1
    @Zipper1365 - it would be good of you to write that up in an answer. Certainly leave your up vote & check mark here, since Ack helped you out so much, but because your answer is buried in a comment, others might not read all the comments and see your answer.
    – FreeMan
    Aug 22, 2021 at 15:32

After more investigation, it turns out that this was/is standard 1/2" copper that had a solder-lined sleeve over it. The valve and the sleeve were a packaged deal. That's why the walls appeared thicker and that's why nothing fit it to do what I wanted.

The photos in this question show the sleeve quite well. In my case, unfortunately, the end of the sleeve was in the wall and not visible for my initial assessment.

The pipe cutter obscured the two layers in the cross section and likely also added an internal lip that gave me an incorrect inside diameter reading.

I have since been able to get heat and pliers on it and was able to painstakingly remove the sleeve peeling back bit by bit like a bad tin can lid. After peeling back enough of it, I was able to attach a standard compression shut off to the stub.

Soon after adding the compression shut off, I realized that in my heavy heating to de-solder the sleeve as I peeled it back, I may have melted an upstream fitting. Not knowing how far away that might be tucked in the wall, I opened the wall and found a questionable looking upstream elbow joint just behind the drywall.

I replaced the elbow and stub like I should have just done in the first place.

New elbow and stub sweated on

Finished product


I have the same issue-in New England this was common into the 1990s. This is a chrome plated copper tubing used for toilet water feeds. 11/16” OD is correct. Only solution is to call a plumber. Not something you can get at a Home Depot/Lowe’s.

  • 3
    Not sure that "call a plumber" is "the only solution", since the OP had another solution noted in the comments on the accepted answer. Of course, that points to putting answers in comments as a Bad Idea™, since people miss information when that's the only location for it.
    – FreeMan
    Aug 22, 2021 at 15:26

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