Soldering copper pipe, or "sweating" as they call it in the trades, relies on capillary action to create a well-sealed joint. By using a propane torch to heat up the two pieces you are joining, solder is "sucked" into the joint and spreads evenly between the pipe and fitting. Once it cools, you should have a solid, leak-free joint that will last for years.
- Always use lead-free solder and rosin flux for plumbing projects.
- Always use caution when using a torch near wood. Cover the wood with a piece of sheet metal to prevent direct exposure to the torch flame.
- Don't be in a hurry. If you don't properly prepare the pipes for soldering you may end up with leaks. Then you will need to completely drain the water out of the pipes you are working on. It is impossible to solder pipes with water in them.
- Before you solder the pipes together, assemble all the pieces to make sure your have a proper fit and no unforeseen problems.
- Pipes cannot be soldered if water is in them. Water prevents the pipes from reaching a hot enough temperature to melt solder. Use a piece of bread (without its crust) and shove it in the pipe to hold back a gradual flow of water. The bread will dissolve when the water is turned back on.