I removed a coupling I soldered on so that I can solder a new one on the way I had originally intended. The pipe is now coated with solder. Do I need to sand all of it down to the copper again before applying more flux? I would just cut the pipe, but it is situated in such a way that cutting even an inch off of it would require enormous amounts of extra work.
Just get it hot, add some flux and wipe clean with a wet rag (just be careful to avoid getting burned!). From this point, rough it up a bit with sandpaper, and as long as you can insert the new fitting, you should be OK to continue on.
^What he said, except I use a dry rag for that, as a wet rag will cool the solder a lot quicker and you will get less of it off. Generally, as long as the fitting will slide on to the pipe all the way, the new solder will bond with the old.
Phish is absolutely correct. Use a dry rag, it works better. I was just thinking "wet" to clean freshly soldered pipes...not to clean up. Thanks for the correction Phish!
So one of the pipes didn't look completely round and the coupling didn't fit quite right, but it was too close to the drywall to cut. I cut part of the drywall away and found a metal plate behind the drywall. The pipe goes through this plate. There is less than 3 inches of pipe coming out from the plate, but I only need to cut off about a centimeter. I assume it won't hurt anything to solder a coupling on that close to the plate, and that it won't hurt anything that I removed the drywall and exposed it.
I would think you will be fine. That plate is also soldiered to the pipe and is there to keep it from moving around. I did the same thing when replacing my water heater and just patched the drywall back.
re-soldering
Linear Mode
