Plumber how-to
How to Sweat a Copper Pipe Joint
Soldering (sweating) copper is a fundamental plumbing skill. Work in a ventilated area and keep a fire extinguisher nearby.
Soldering (sweating) copper is a fundamental plumbing skill. Work in a ventilated area and keep a fire extinguisher nearby. In short: shut; cut; clean, then complete the remaining steps below.
Step by step
Shut off and drain the water line.
Cut the pipe square with a tubing cutter and ream the inside burr.
Clean the outside of the pipe and inside of the fitting with emery cloth or a fitting brush until shiny.
Apply a thin layer of flux to both surfaces and assemble the joint.
Heat the fitting (not the solder) evenly with the torch until the flux sizzles.
Touch lead-free solder to the joint opposite the flame; capillary action will draw it in around the joint.
Wipe excess flux, let the joint cool naturally, then turn the water on and check for leaks.
Safety reminders for plumbers
- Use ventilation and respirators when required for fumes and chemicals
- Follow confined-space and trench safety rules
- Wear eye protection when cutting, soldering or using drain machines
- Wash thoroughly after exposure to sewage and get recommended vaccinations
Key terms
DWV · P-trap · Vent stack · Cleanout · Backflow preventer · PEX: see the full plumber glossary.