Fixing threads in an old steam pipe elbow.

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by DIYJP, Oct 30, 2008.

  1. DIYJP

    DIYJP New Member

    Messages:
    2
    I am fixing up some 1937 Warren-Webster in wall radiator valves that are leaking. These were converted from steam to hot water years ago. In the process, I came across a badly rusted 3/4" supply nipple that extended down into the floor that I felt needed to be replaced. I was unable to loosen it so I cut it off and dug the nipple end out of the elbow. As I have done before, I used a dremel to cut the inside of the bad nipple so I could collapse it for removal.

    Unfortunately, this time one of my cuts went completely through the threads perpendicular, top to bottom and I ruined the fitting. I have searched this and other places on the web and find that attempting twist off the old elbow will certainly only make matters worse.

    I found that a product like Harvey's Plumber Epoxy Putty supposedly can be used to repair threads and pipes but see mixed reveiws on how permanent it might be but none addressed my situation specifically. I got some and played around with it by using my dremel skills on a new fitting I made a new ruined fitting to test it. I then applied the epoxy and ran a tap through it once it hardened. It seems OK visually but I would like some expert opinons from those that have used this stuff. Perhaps this is the perfect application as it must be good for something.

    Lastly, I have just read a thread here (Steam Pipe Removal) that mentions cracking the old elbow off and replacing it verses trying to twist it off. Perhaps that is a better option but short of using a nut splitter I would have no idea how it is supposed to be done.
  2. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    Two hammers. one backing, one striking. Be carefull. When you see the crack, stop hitting and twist it off.
  3. hj

    hj Moderator & Master Plumber Staff Member

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    Location:
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    elbow

    It has to be a cast iron elbow to crack it off.
  4. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    If its an old steam system, it will be a cast iron fitting
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,631
    Location:
    Cave Creek, Arizona
    elbow

    99% of the time, but they could have used malleable on the smaller sizes.
  6. DIYJP

    DIYJP New Member

    Messages:
    2
    Thanks for your responses.

    Am I striking the end that is attached to the pipe or the open end? I do not want to damage the pipe threads. Will this break easily? I do not have much swing room because this fitting is down in the floor. I might be able to hold a 3 lb mallet under it and hit it with a small hammer. I like the idea of breaking the old elbow off but is the epoxy thread repair I described totally out of the question?
  7. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    Epoxy won't hold for long. Be carefull and take your time. When you see a small crack you should be able to spin the broken fitting off without damaging the nipple.

    May the force be with you.
  8. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    Hit the hub of the cast iron elbow that is attached to the pipe , with the mallet firm up against the opposite side that you are going to be hitting.
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