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Thread: how to get water out of copper pipe to solder it properly

  1. #1
    DIY Junior Member dy's Avatar
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    Default how to get water out of copper pipe to solder it properly

    All the soldering with the copper pipes has been going ok. But theres one pipe that seems to be giving us a problem. How do you solder the copper pipe with water in it. We have tried sucking the water out with a straw..but that didnt seem to work. It will not solder with even the slightest amount of water.
    Hope you can help,

    thanks
    Last edited by dy; 05-10-2010 at 04:38 PM.

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    As you've found, liquid water won't let the joint get above the boiling point which is not hot enough to melt solder. They make some plugs that dissolve that will give you awhile to solder the connection. In a pinch, people also use white sandwich bread (no crusts, no fancy stuff with seads), which will also disolve when flow is restored. It can leave bits around, but does work. There is also a tool called Jet-Sweat you may be able to rent (they're expensive to buy), and there are machines that will freeze the pipe to make a plug. Open a valve higher up to break the vacuum (think finger over a straw), and wait longer for it to drain off.

    Keep in mind that you must have an opening for the steam and super heated air to escape on the 'last' fitting, or you'll get a pinhole leak, causing the fitting to leak. You can do this by leaving a valve open in the line (preferably close).
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    DIY Junior Member dy's Avatar
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    Default pinhole leaks in copper pipes - soldering

    I have managed to clear the pipe of water, we are on the last fitting. I removed a piece of the old pipe and replaced it with new. I am trying to connect a new piece with the existing old pipe. Prior to doing this i did encounter a pinhole leak. just above the problem area, i had no problem achieving a good solder. I do not know why that on the pipe i am achieving differnet results. within a 2" area. I have opened up a valve on the bathroom sink, and the toilet, though the area we are working on is the shower and do not have ne valves. any suggestions would be greatly appreciated. thanks for your assistance.

  4. #4
    DIY Junior Member dy's Avatar
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    pinhole leaks in copper pipes - soldering
    I have managed to clear the pipe of water, we are on the last fitting. I removed a piece of the old pipe and replaced it with new. I am trying to connect a new piece with the existing old pipe. Prior to doing this i did encounter a pinhole leak. just above the problem area, i had no problem achieving a good solder. I do not know why that on the pipe i am achieving differnet results. within a 2" area. I have opened up a valve on the bathroom sink, and the toilet, though the area we are working on is the shower and do not have ne valves. any suggestions would be greatly appreciated. thanks for your assistance.

  5. #5
    Moderator & Master Plumber hj's Avatar
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    You suck it out, Blow it out. Or find a lower area where you can drain it out. IF there is ANY water in the joint you will spend all day heating it and it will NEVER solder.

  6. #6
    Retired Defense Industry Engineer jadnashua's Avatar
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    The pipe needs to be cleaned well along with the fitting. Then, you need a good coating of flux. Then, especially if it is the last fitting, you still need an opening to open air. There may be some water trapped between where you were working and those valves that are open. If so, the heated air will raise the pressure and can blow through the molton solder at the fitting. You need an opening closer. Was the shower valve in the open position?
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  7. #7
    DIY Junior Member K.'s Avatar
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    Try some tubing perhaps rather than a straw? Worked well for me since it was flexible to pass through one or two bends and thus reach farther down into the pipes, and get more of the water out.

    -Jonathan

  8. #8
    Forum Admin, Expert Plumber Terry's Avatar
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    The best way to drain down a house is to open every faucet in the house.
    That's how the plumbers are doing it.

    Sometimes the homeowner will start closing valves, I guess they don't like hear air sucking down the pipes.
    When they do that, it takes us longer.
    Longer means, it just upped the cost.

  9. #9
    In the Trades dwindle's Avatar
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    With the whole system open, suck the water out with a shop vac or blow it out with a compressor.
    If there is any closed valve, water will stay trapped in its pipe and dribble into the pipe your working with.

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