Problem sweating second joint on a fitting

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by camner, Jul 22, 2009.

  1. camner

    camner New Member

    Jan 10, 2009
    It's been a while since I've sweated copper pipe, and I'm running into a new (for me, anyway) problem...

    I assembled the whole thing, cleaned and fluxed, and started sweating the joints. I noticed that the first joint on a fitting typically went very well, but the second one often didn't. The solder just wouldn't flow right.

    I think what was happening was that the flux in the second joint of the fitting was just getting oxidized out while I was sweating the first joint.

    How does one avoid that, especially on smaller joints such as couplers?

    And a second likely is it that a joint that passes muster when first put under pressure will fail sometime later? Can I be fairly certain that a joint passing the initial pressure test will remain good?
  2. Cass

    Cass Plumber

    Nov 12, 2005
    Ohio the tubing open to the air some where so that your not trying to solder a closed system...?

    You are most likely getting the fitting to hot....try heating the whole fitting at the same time..
  3. Sponsor

    Sponsor Paid Advertisement

  4. Jay Mpls

    Jay Mpls Master plumber

    Sep 29, 2008
    Master Plumber /Sewer rat
    It is always my luck after the house has drained down I have to outlast or outwit water from something.Kind of sounds as though you *may* hae been fighting water.
    Every now and again I have expansion from the water heater to contend with.
    On a short closed system you may have been fighting pressure from your own heat.
    Beyond that, it's all in the preperation!
  5. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona

    Do not stop after each joint. Do one, usually the largest, then the next, and so on. For a vertical line do the lower joints first and then work upward.
  6. camner

    camner New Member

    Jan 10, 2009
    Thanks all for your help.

    It turns out the issue was flux. I originally bought a "kit" containing some solder, some flux, and a flux brush, and the flux was obviously not very good. I ran out, went to the store to get some more, and the guy there said "don't use that junk..try this!". And "this" worked wonders. Every joint I sweated after that worked perfectly (and I don't think my technique had miraculously improved, either!).
Similar Threads: Problem sweating
Forum Title Date
Plumbing Forum, Professional & DIY Advice Problem sweating a shut off valve Jun 9, 2008
Plumbing Forum, Professional & DIY Advice Sweating copper pipe problem Jan 2, 2008
Plumbing Forum, Professional & DIY Advice Sweating problem... Jul 28, 2006
Plumbing Forum, Professional & DIY Advice Mixing valve it me or the valve(s) Oct 12, 2017
Plumbing Forum, Professional & DIY Advice Tankless water heater flow switch problems Sep 29, 2017

Share This Page