I've done lots of repairs on stuff like this. I've plumbed houses and done lots of retrofitting. You have no choice but to cut it off and retrofit a new piece in. You'll never get that apart no matter what you do. Attach a length of pipe to make up for the cut pipe.
You might want to get a plumber if you've never done any soldering. It may save you a lot of heartache and hassle. But if you do want to DIY, this is what I'd do....
- I'd cut the pipe and leave it as long as possible but at least 3/4" away from any fittings, longer if you can. Sometimes solder can end up inside the pipe when they originally soldered it and you'd like to avoid that.
- In order to resolder to that pipe, you have to to clean it up so it's shiny copper again where you are going to fit the new pipe. Solder won't stick to oxidized copper. You clean it up with wire brushes or sandpaper. That pipe is pretty heavily oxidized so it is going to take some effort. You might be able to get a wire brush in a drill and clean it - that'd be my first and preferred approach. In fact, depending on the situation, you may want to clean the pipe up before you cut it.
- To cut it, you might be able to use a short pipe cutter like this
because its up against the wall. It you have one, you could also use a powered multitool like this
to cut it. Virtually every manufacturer offers these. Cordered versions are less expensive than cordless tho the Ryobi is pretty cheap.
- Now your ready to put a coupling and the new hose bib on that pipe. There's lots of Youtube videos on soldering copper pipe. Get some spare fittings some extra pipe to practice before doing it. You have to get a small wire brush designed to fit into the fittings to clean its inner surface. The key to soldering is to make sure you use flux on all parts of the pipe and fitting that will be soldered. When you apply the torch, apply it only to the fitting and let it heat the pipe. Apply the torch to the far side of the fitting away from where the pipe enters. It doesn't take too much solder but most people apply too. That won't hurt, you just get a glob of solder on the fitting. Don't worry about it, it won't hurt. When your done, wipe the residual flux off the pipe and fitting with a rag.
- I suggest putting the hose bib on last. You don't want to melt any non metal parts that might be inside it. I don't know anything about cold-weather hose bibs and special prep for them.
In fact, maybe a better idea is to sell the house and move to a place that is more habitable where you don't have to worry about freezing😎.
Hope all that helps! Don't hesitate to ask if you have Qs.
Last edited by Miguel on Tue, 22 Jun 2021 12:28:47 +0000; edited 1 time