This is for beginners that have soldered a pipe but not been successful in soldering the joint correctly causing the joint to leak. It's an easy fix once you know how.
This is fine as long as the original fault is just insufficient solder or insufficient dwell time of the torch on the joint, resulting in solder not fully flowing before the joint cooled. But if the joint preparation wasn’t sound, i.e. the ends of the pipe weren’t cut cleanly, or the mating surfaces weren’t properly cleaned, or there wasn’t proper depth of insertion at an acceptable angle, this quick re-heating remedy may well not work.
Fry Power Flow solder. Contains Lead: Not to be used on potable water supplies. If you plan on soldering potable water supplies then don't practice with lead solder, use what you would use in the field... or practice with both types. Leaded solder flows much easier than non-lead solder and the sudden change in how it flows might trip you up at first and make you think you are doing something wrong. So practice with what you plan on using in the field or practice with both types to get a feel for the differences. Just my 2 cents worth.
The real problem is getting water out of the pipe and often the pipe must be cut to do that which means adding and sweating in a slip coupler where the pipe was cut to drain the line..
Sometimes if you don’t have any other fittings close by the one that’s leaking you can drill a small hole in the bottom of the pipe and then braze it once you get the water out
