Project Guide

How To Solder Copper Pipes

Prepare Inside of Fitting
A person preparing the inside of a pipe fitting

Ream the inside of each fitting with a wire brush.

Clean Outside Of Pipe
A person cleaning the outside of a pipe fitting
  • Use emery cloth or steel wool to clean the outside of the pipe. 
  • Use a deburring tool or the handle of a pair of pliers to deburr the inside of the pipe.
Apply Flux to Pipe
A person applying flux to a pipe fitting
  • Apply a thin layer of lead-free soldering paste (flux) to the end of the pipe using a flux brush. The paste should cover about 1 inch of pipe.
  • Insert the pipe into the fitting, making sure it is tight against the bottom of the fitting.
  • Twist the fitting slightly to spread the flux.
Unwind Solder Wire
A person holding a copper pipe

You will need 8 to 10 inches of the wire extended from the spool. Bend the first 2 inches to a 90-degree angle.

Heat the Fitting to Sweat the Copper Pipe
A torch being used to sweat a copper pipe
  • Light the propane torch.
  • Hold the tip of the flame against the middle of the fitting for 4 to 5 seconds or until the soldering paste begins to sizzle.
  • Heat the opposite side of the fitting to ensure the heat is evenly distributed.
Touch the Solder to the Pipe
A torch being used to solder a copper pipe
  • When soldering copper pipe, first touch the solder wire to the pipe. 
  • If the solder melts, the pipe is ready to solder.
Remove Flame from Fitting
A copper pipe featuring a solder joint

Quickly insert ½- to ¾-inches of solder into the joint.

Clean the Fitting
A person cleaning a copper pipe fitting
  • Wipe away the excess solder with a rag.
  • After the pipe and fitting have cooled, install the pipe, turn on the water and check for leaks.
  • If the joint leaks, take it apart and re-solder it.