Murphy's Law of Soldering

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by SH140, Jun 10, 2013.

  1. SH140

    SH140 New Member

    Jan 31, 2013
    Vallejo, Ca.
    After sweating new shower plumbing, (all new pipe & fittings), during leak test I discovered one joint with a very small leak. Somehow I missed it when soldering the rest of the joints. I turned off the water, drained the system, and soldered the connection. It doesn't leak now, but because the flux was exposed to water before it was soldered, will it be a problem in the future?

    Also, I had another joint that leaked. Naturally it was on the pipe that is behind everything else, is sweated to the mixing valve, and would be the biggest pain in the a** to replace. So I warmed it up a little, and added more flux, then heated up the connection and re-applied solder. Supprisingly this worked. Was this some lucky fluke, or does the previous solder re-flow when it gets hot and seal the leak?

    As I stated earlier, to remove & replace these joints will be a major hassle, but if I don't, what are the odds of a leak in the future? Definitely don't need that !!
    Will either of the 2 mentioned "do-overs" be OK to leave as-is?

    If it's recommended to replace connections, any recommendations on how to cut pipe when there's no room for a tubing cutter? Even a mini size won't fit. I can't pull connectors apart either after heating up, as I tried that already.

    Thanks !

    P.S. I did clean, brush & de-burr everything before installation. Repair was done late Sunday afternoon, so far no leaks under normal water pressure.
    Last edited: Jun 10, 2013
  2. Gary Swart

    Gary Swart In the Trades

    Sep 1, 2004
    Yakima WA
    Basic principle of soldering. Water contaminates (for the purpose of adding solder) the poor joint. You can not just reheat and gob more solder on. Sure, the glob may stop the leak temporarily, but it will not last. The only way to fix the joint is to disassemble it completely and start from square one. Cutting pipe is far easier with a tubing cutter, and better than sawing, but sometimes you gotta do what you gotta do. I've used a fine metal cutting blade in my jig saw. Sure it leave a nasty burr even with the fine blade, but it can be done so the cut is reasonably square. The burr has to be removed which will take some time and effort.
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  4. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona

    1. If the joint leaked the solder did not fill the gap 2. water flowing thrugh the poor joint, washed the flux away and contaminated the copper 3. Solder did not flow to repair the joint because of $1, and 2, above. So all you did was make a "fillet" joint on the surface of the fitting, and who knows how long that will last. It could last "forever", or it could start leaking tomorrow.
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