How To Sweat Copper Pipe Joints

Every homeowner should know how to sweat copper pipe joints. Straight copper pipes are connected by joint fittings that allow the pipes to turn corners or fit into the wood house framing. To sweat a copper pipe joint means to attach copper joint fittings to copper pipes or tubing and solder that area with a torch and solder.

To sweat copper pipe joints, you will need:

  • Emery cloth
  • Round wire brush
  • Flux Brush
  • Flux
  • Torch
  • Solder
  • Cloth
  1. Shut off the main water supply to the building. Open the faucet to drain the remaining water from the copper pipe. Dry fit (without flux) all the fittings on the copper pipe to make sure everything fits together correctly, make any necessary adjustments, then take the fittings off.

  2. Clean the ends of the straight pipes with emery cloth to remove dirt, debris, and grease (including fingerprints) from the copper. Clean the inside edges of the copper fitting with a round wire brush.

  3. Apply flux with a flux brush to the ends of the copper pipe and the inside edges of the copper fittings then assemble the fittings onto the copper pipe. Prepare the solder by unwinding 10 inches and bending the end into a 2 inch J shape.

  4. Light the torch and adjust the flame to 1 ½ inch. Hold the flame to the copper joint and heat the joint for 30 seconds. Touch the top (highest point) of the joint with the solder. The solder will seep into the joint and surround it. When solder drips from the bottom of the joint, the joint is filled with solder. Wipe the joint with a cloth to remove excess solder and to make the solder smooth on the joint. Note: Use caution because the joint is very hot.


  • Wear protective gloves and safety glasses when using a torch to avoid burns or injury.
  • Warnings
  • Before using the torch, cover anything flammable in the immediate area with sheet metal to avoid starting a fire.

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