Copper Pipe Sweating Question

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by crosby1, Feb 24, 2008.

  1. crosby1

    crosby1 New Member

    Messages:
    28
    Location:
    Virginia
    i'm getting ready to install a shower rough-in valve and all associated plumbing connections.

    i need to attach a few elbows to the valve before installing it.

    question: if i sweat the elbows to the valve and then come back to sweat the pipe to the elbows, how do i prevent the 1st solder joint from breaking down and coming apart when i reheat the connections?

    thanks.
  2. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    If you can solder some pipe to the 90s at the same time and cut it back to the right length later that will take care of the problem.
  3. crosby1

    crosby1 New Member

    Messages:
    28
    Location:
    Virginia
    thanks cass,

    so really, all fittings have to be sweated both sides at the same time?

    no way to do one side of a fitting then come back to do the other without screwing up the first one?

    one more (stupid) question: when sweating a vertical fitting (like a straight connector), how does the solder go "up" into the bottom part of the connector? is it just capillary action?

    thanks again.
  4. seaneys

    seaneys New Member

    Messages:
    192
    Location:
    Chicago Suburbs
    Could you also use wet towels in a pinch? I'm curious..

    Thanks,
    Steve
  5. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    Not really... I'd do both at the same time.
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,006
    Location:
    New England
    You really should do both sides of an elbow at the same time. If other connections are close, then a damp rag should keep the ones you've done intact. If you dry fit everything, then solder, it can work out well.
  7. frenchie

    frenchie Jack of all trades

    Yeah, pretty much. Solder's drawn in by the flux.

    I've never heard of anyone successfully soldering one side of an elbow, then the other.

    Sweat on a short length of pipe, then use straight couplings to connect to the roughed-in pipes.
  8. Lakee911

    Lakee911 I&C Engineer (mostly WWTP)

    Messages:
    1,328
    Location:
    Columbus, OH
    Really? I've sweated a lot of one side of connections on the bench and then brought it in the field and soldered in the other half. Elbows and 45s included.
    Then again, I don't just hang the whole contraption from the elbow while I heat is. Is that the issue?
  9. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    Any movement of the original joint could yield a cold solder joint.
  10. frenchie

    frenchie Jack of all trades

    Okay, I've never heard of anyone doing it... until now!:D
  11. plumbingskool

    plumbingskool Retired Tradesman

    Messages:
    49
    Location:
    NY

    No?

    I do it all the time,

    If you know how to work with solder and flux it can be done easily , But if you are a beginner I would advise to listen to the others :)
  12. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    I always do one then the other... A couple of seconds apart!

    I'd like to do them both at once but its just to hard to apply the solder to 2 joints at once... Sorry I'm not that good!
  13. shag_fu

    shag_fu New Member

    Messages:
    31
    Location:
    Illinois
    When I solder 2 side of an elbow at dif time I always reclean and flux the unsoldered connection. Ive had no problems. I run into that situation alot with male/fem adapters. Put the first piece into the adapter, dope and tape, screw into whatever, wet towel on the joint and solder away.
  14. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    Its more common than most people think. You may have a scenario where the one side of the 90 is right at the egde of the drywall or combustable area where you do not want to put direct flame. I find it reassuring that the joint has solder around it and you can visually see it as apposed to guessing.

    I don't recommend that inexperienced folks try this, you may end up cursing a blue streak.
  15. frenchie

    frenchie Jack of all trades

    Well, I be...

    ...learn something new every day!

    I'd have thought for sure the old joint would let go when you re-heated the fitting.
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