Connecting 1/2" copper to old 3/4" brass pipe

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by sean farrell, Jun 5, 2012.

  1. sean farrell

    sean farrell New Member

    Messages:
    5
    Location:
    Boston
    Hello,

    I am doing my bathroom over. There is still some old pipe in the walls that looks to be 3/4" threaded brass. In some places the 3/4" brass has been connected to copper. It looks like the 1/2" copper was just inserted into the cut 3/4" brass and then soldered.

    I have to do something similar and I am wondering if this is the correct approach. If yes, is there any trick to doing it? If no, what is the correct way?

    Thanks
    Sean
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,062
    Location:
    Cave Creek, Arizona
    IF your description is correct and it is really brass pipe, then the proper connection is to thread it and use copper to IPS adapters.
  3. sean farrell

    sean farrell New Member

    Messages:
    5
    Location:
    Boston
    Thanks HJ, I am pretty sure it is brass based on the fact that if I scrape away at it the metal is yellow and the age of the house (about 80 years).

    I don't have the kit to cut threads and would like to avoid buying it for two joins. I do have access to existing joins (elbow fittings). What are my chances of unscrewing the pipe at these joins and ending up with clean reusable threads that I can then attach the IPS adapters to? I have heard that old brass is brittle to work with. Can I muscle it and expect good results?

    Thanks.
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,062
    Location:
    Cave Creek, Arizona
    Old brass is seldom "brittle" and almost always unscrews fairly easily.
  5. sean farrell

    sean farrell New Member

    Messages:
    5
    Location:
    Boston
    Hello HJ, I'm not familiar with plumbing terminology. Does IPS mean Iron Pipe Standard, in which case are these the standard sized couplings I can get at the big box stores. I have purchased a 1/2" NIBCO coupling, with a 1/2 female one side and threaded on the other. The threaded side looks about the right side but just wanted to check this is what you meant before cross threading it or something.

    Sean
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,062
    Location:
    Cave Creek, Arizona
    IPS is "iron pipe size" which is the ONLY size you will find at hardware and plumbing stores. Couplings should be threaded female pipe on BOTH sides.
  7. sean farrell

    sean farrell New Member

    Messages:
    5
    Location:
    Boston
    Well, it did not go well. First joint I tried to unscrew, the pipe at the next joint snapped off from the torque even though I was holding the pipe above with a clamp.

    The joint was corroded. Where the pipe snapped the metal is light pink and easy to scrape all the way through on the break line. Next I cut the brass pipe below and tried to insert and solder the copper. It leaked. It is horizontal and difficult to get at to solder.

    So now we have no hot water...
  8. Terry

    Terry Administrator Staff Member

    Messages:
    15,316
    Location:
    Bothell, Washington
    It can help to apply some heat to the female fittings only when unthreading. It makes the fitting larger for a moment.

    Holding the pipe above with a clamp?
    I don't know what that means, but I like to use pipe wrenches on both the fitting and the pipe.
    It's one of the rare times as a plumber that I use a pipe wrench. Most of the time I get by with pliers or my hands.
    Last edited: Jun 7, 2012
  9. sean farrell

    sean farrell New Member

    Messages:
    5
    Location:
    Boston
    Thanks Terry,

    That's pretty much what I did, except for the heating part. I have decided that the best course of action is to remove all the old brass pipe. I see similar corrosion on many of the joints, so I don't think it is to be trusted. I managed to isolate the broken line, so now we have water in the rest of the house. Next job is to try to fish PEX from the second floor to the basement by pulling it down behind the old pipe! Hope that goes better.
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