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I have a copper T joint that is leaking on one side, what is the best way to repair this joint that does not involve cutting the joint out and starting over?

-- Update --

The pipe in question is for hot water and is soldered together.

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If the copper pipe is for water not gas, you can drain the pipe so that at least a couple of feet below the joint is free of water, then clean the joint, apply flux, protect adjacent walls and fitting, heat the joint with a blowtorch and apply solder. There's a chance you'll make the situation better rather than worse. –  RedGrittyBrick Apr 22 at 11:23
The proper solution is the cut out the joint and start over. If you're not able to fix the problem correctly the first time, will you be able to fix it correctly the second time you have to fix the same issue? –  BMitch Apr 22 at 14:00

4 Answers 4

up vote 1 down vote accepted

Nothing needs to be cut, barring a very strange installation. Unions in soldered copper pipe sytems are extremely rare, and there's good reason for that.

Applying more solder and flux without disassembly (note: not cutting) is unlikley to work.

Assess your ability to use a torch without burning the house down - a plumber is a lot cheaper than even a small fire. If you pass that test, drain the pipe, leaving the nearest taps open (don't want any steam pressure to build up) apply flux, apply heat, and pull on the pipes. There is nearly always enough give in the piping system to allow joint disassembly. If present, a few clamps of the "hold pipe to wall" type may need to be loosened to provide that give.

With the pipes apart, clean the joint surfaces inside and out throughly. Start with a damp rag in a gloved hand to wipe off as much solder as possible when the solder is still molten from heating to pull it apart. It may be worth using a new Tee, but even on new fittings, clean the surfaces throughly - it's essential to getting a good solder joint. Apply flux, reassemble. Apply heat to the joint GENTLY and dab with the solder (not in the flame - to the pipe/socket interface) watching for the point where the pipe/fitting melt the solder and pull it into the joint. Excessive heat is BAD, and can only be solved by disassembling and cleaning again.

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I've never had luck pulling a poorly soldered joint apart. Between the cramped locations I'm working in, the tight connections that barely move without solder, and the high heat required to melt the solder, I usually end up warping the pipes with the pliers while attempting to separate them. Any time I see professional plumbers repairing a problem, they usually start by cutting the pipe, it's a lot easier and quicker. –  BMitch Apr 22 at 14:05
Plus the water in the undrained pipe sucking all the heat out as it boils. –  Fiasco Labs Apr 22 at 14:54
@FiascoLabs - Missed the "drain the pipe" step? I consider it so blindingly obvious I didn't have it in my first draft, but it was there before your comment was written. –  Ecnerwal Apr 22 at 18:47
@Ecnerwal - it was more a comment on what BMitch said, having attempted it once early on in my plumbing endeavors. The gloop, gloop noises with nothing happening, priceless! –  Fiasco Labs Apr 23 at 0:46
Trying to re-use already soldered copper fittings is foolish in my estimation considering that new fittings are not very expensive. You'll spend more time, gas and misery trying to pull the old fittings apart than to cut and start anew. –  Michael Karas Apr 23 at 3:16

If this is soldered copper slip joint fittings there really is no other choice other than cutting out the faulty parts and starting over.

Sometimes when undertaking a repair like this it can be advantageous to incorporate a UNION fitting into the line to permit the last connections to be joined together. A union fitting looks like this.

enter image description here

When assembling the union into the piping system do not forget to slide the brass nut part onto the pipe before soldering the unthreaded coupling part onto the pipe end.

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I am assuming you have a pin hole leak and the pipe is holding water. Not gas.

If the leak is small, a drip, and it's located on one of the arms of the T, you could potentially wrap the arm with gasket rubber and put a hose clamp around the gasket material. This is a temporary fix and the only correct way to fix this is to replace the T. But since your requirement is to do it without cutting the pipe either do it this way or via the method described in the first comment (drain and solder). Make sure you cut a piece of gasket rubber large enough to wrap the entire circumference of the pipe and wider than the hose clamp you're using. If the pin hole is directly opposite the intersection of the T, you might have to drain and solder as you won't be able to apply pressure with the hose clamp.

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Thanks for your input, not interested in a bandage, just wanted to know if I could fix it properly without removing the joint altogether –  iamkrillin Apr 22 at 15:50

If the real reason you don't want to cut it out is because you don't want to solder anything back in, consider something like Sharkbite connectors. These connectors are snap-on fittings for copper pipe. You just cut out the bad section of your copper pipe and replace it with equivalent Sharkbite fittings. It's almost as easy as Legos.

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