Plumbing – Is it ok to unsolder an outdoor spigot and to solder back a new one without cutting the copper pipe

I wanted to post what I did to fix the problem in case it helps anyone. I did not have to do anything with the drywall or damage the outside of the house either. The most difficult thing to do was getting the solder into the wall to apply to the joint.

I purchased the following items from Home Depot.

1. Plumbing soldering kit that came with propane torch, solder, flux.

2. Copper 1/2" male adapter so that I could simply screw the new spigot on: http://www.homedepot.com/p/1-2-in-Copper-C-x-MPT-Adapter-C604HD12/204620255

3. Threaded 1/2" spigot: http://www.homedepot.com/p/1-2-in-Sillcock-Multi-Turn-Female-Thread-to-Pipe-Valve-UV65204/206827980

4. Thread tape

I fixed it as follows:

1. I tore up an old sock and stuffed it in the copper pipe to soak up the water.
2. I used some sand paper to clean off the old solder on the pipe.
3. Remove the sock.
4. Apply flux paste to the outside of the copper pipe coming out of the house.
5. Push the male adapter onto the copper pipe. Make sure the flux paste was applied to the correct length.
6. I had a very tight spot to work with, and the solder wire needed to reach back into the wall to where the joint was at, so I went ahead and straightened out a piece of solder about 7 inches long with a tiny bend at the very end. This is the only way I could apply the solder without removing material from the wall.
7. I used a water bottle to spray a good bit of water into the wall to dampen everything up.
8. Fire up the torch and apply heat to the male adapter. I couldn't apply heat directly to the joint since it was inside the wall and I didn't want to catch anything on fire. It took a while to heat the entire adapter up.
9. After the male adapter is sufficiently heated up, I poked the solder into the wall and applied it to the joint. I then pulled it back out, made another tiny bend at the end of it, and stuck it back in on the other side to make sure that it was soldered all the way around.
10. After letting it cool off, I applied the thread tape to the male adapter and screwed on the spigot. I turned on the water and made sure it works.

It seems to be fixed. It's been a few days and I haven't noticed any leaks.

There are several possibilities to consider.

1. If you had really cleaned the joint beforehand with emery cloth or steel wool (both parts of the mated joint) there there is a good chance of a decent joint. The cleaning action helps clear out any oxidation on the parts that prevents the solder from adhering to the copper. (Keep in mind though that the simple act of applying heat to the joint also brings on oxidation.

2. If you had happened to be using a rosin core silver solder that flux built into the solder wire may have been more than enough to clean the joint for proper soldering.

3. An improperly cleaned joint may appear to not leak because it is tight or a small amount of solder may have flowed into the joint but it is no substitute for a properly made joint. One way to understand the sweat process success is to carefully observe how the solder sucks into the joint just as the silver solder wire is touched to the joint and melts.

So if your situation is like #3 (and possibly #1) you will really probably want to take things back apart and re-do this work. Last thing you want is for the joint to come apart under mechanical stress on the pipe or start leaking after a year of so of thermal cycling of the joint.

It can be really be worth while to get a handfull of copper fittings and a length of copper tubing and practice a dozen or more test joints to get the techniques down. (Note that standing water in or on a pipe near where you are soldering can be a huge detriment to getting good sweat joints.