Home>Discussions>PLUMBING>Re-sweating leaky joint on copper?
5 posts / 0 new
Last post
John in Manhatt...
Re-sweating leaky joint on copper?

New problem..
I have a leaky joint and want to know if I can re-sweat it with new solder... or... do I have to take it all apart, clean and re-sweat?
It's a 2" inline sleeve connector that is spewing from the top. The corrosion around the top of the sleeve is moderate and the leaking isa small spray. I'd like to clean it up(externally) and sweat some new solder into it. Yes?

Re: Re-sweating leaky joint on copper?

You have to take the old joint apart, clean every thing & sweat.
I would toss the old joint(elbow, Tee, etc.) & use new, but the old can be used if thoroughly cleaned. Use a wire brush as well as emery.
One reason you can't resweat without taking it apart is because of water in the line.

Re: Re-sweating leaky joint on copper?

To add to what Ed mention you need to take it apart to clean and add flux to the joint. The flux sucks the solder into and around the connection. Just soldering the outside of the joint does not provide a good seal. Also as Ed mentioned if you don't get all the water out you will never get the joint soldered properly. Hope this helps you out.


Re: Re-sweating leaky joint on copper?

If your joint currently has a small hole/leak...you won't be able to simply apply a torch to it and get it hot enough to take the joint apart. That because the water inside will wick the heat away and you'll never get it hot enough to melt the solder.

Consequently, you'll almost certainly have to cut the pipe again a couple inches from the leak to let ALL the water out. Take you time and get it all out. Then you'll be able to heat the bad joint enough to remove the fitting and then you'll be sweating two new couplings. Make sure when you sweat these joints that you have a faucet or similar open on this line or the steam/air pressure that develops inside the pipe can/will push the solder you're trying to apply right out of the last seam...leaving you with yet another leak. Don't forget the flux on all surfaces and make sure you have those surfaces shiny bright (brush, steel wool or fine grit sandpaper or emory cloth).

*If* there is some slope to this pipe AND a faucet or similar on the downhill side of the slope that would allow you to completely drain the line as it is...you *might* get away with an external patch over the leak. The patch piece would be made from a short length of the same diameter pipe which is then split lengthwise so you end up with (more or less) a cap of sorts to lay over the leak. It will likely have to be tweaked some to nestle down nicely on top of your pipe. Again, clean all surfaces till they are shiny bright (including the edges of the patch piece), apply a thin-ish layer flux to all surfaces, heat and apply solder around the perimeter of the patch piece. Cross your fingers.

(Always wipe off all surfaces a couple minutes after you're done soldering to remove any excess flux. It's acidic and will eat into the copper if left where it is.)

Re: Re-sweating leaky joint on copper?

It sounds to me like you have a leaking coupling.

Here's what I'd do: first, I'd go and buy a replacement coupling, a repair coupling, and a short length of copper pipe, about 6". (A repair coupling is nearly identical to a standard coupling, except that it doesn't have a should inside. This allows the repair coupling to completely slide over the pipe, instead of stopping halfway.)

SAFETY EQUIPMENT: gloves and eye protection recommended.

Shut off the water to the line with the faulty joint or to the whole house. Turn off the power or set the control to "pilot" on the water heater. Close the supply valve to the water heater. Open up all the faucets in the house to relieve pressure and drain the lines.

Using a tubing cutter, cut out a 6" section of pipe (or however long your short length is) around the existing coupling. Toss this in your recycling bin.

Drain the pipe as best you can. Ball up some white bread minus the crust and stuff this a couple inches into the pipe (both ends) to hold back any remaining water. Do not use other types of bread; the white bread will dissolve.

Using sandpaper or emery cloth, polish all four ends of the pipe. With a wire fitting brush, polish the insides of the new fittings. Apply flux completely inside the fittings and outside of the pipe.

Slide the standard coupling on one of the existing pipes. Slide the repair coupling completely over the other existing pipe. Install the short piece, then slide the repair coupling back so it's centered over the joint (use a tape measure).

With a propane torch, heat the joint until solder melts when it is touched to the joint. Keep applying solder until solder drips from the joint. Repeat the procedure for the other three joints.

Wipe the joints with a cotton cloth. This will remove excess flux and solder.

After the solder solidifies in a few minutes, close all the faucets. Open the main valve and the water heater valve. Remove the aerators from the faucets and flush out the lines. Replace the aerators then turn on the water heater.


You'll notice that I opted not to try and remove the existing fitting. For a coupling, this can be difficult. You also risk overheating and burning the pipe when you try to desolder a joint. If the pipe or fitting is burnt, it can be nearly impossible to solder.

EDIT: I re-read the post and noticed this is a 2" fitting. That's probably on the main line. Because of the size, the bread trick isn't going to work.

Sponsored Stories

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.