How to Connect Soft Copper Tubing

Due to its resistance to corrosion, copper tubing serves many purposes in all types of plumbing systems. Copper tubing provides an excellent means of supplying hot and cold water in the home and is also used in heating systems, particularly forced or gravity hot-water systems. Installation of soft copper tubing is not as labor-intensive as rigid copper, so it can be easily routed around obstacles and connected in a variety of ways.

Sweat Solder Method

  1. Cut the length of soft copper tubing with the circular tubing cutter.
  2. Remove any ridges formed by the cut from the inner wall of the tubing using the reamer.
  3. Clean the end of the tubing with emery paper. Place the connection onto the copper tubing cold, to be sure the end is cleaned as far back as the connector requires. The end must be shiny and scratched from the emery paper, to ensure a well-connected joint.
  4. Apply water-soluble flux to the end of the copper tubing with a small applicator brush. Flux provides additional cleaning and prevents the joint from oxidizing when it is heated. The flux also helps draw the solder into the joint.
  5. Apply heat to both the tube and the fitting using a propane torch, initially heating evenly around the joint. As the joint approaches the temperature at which the solder melts, concentrate the heat more on the socket of the sweat joint, to help draw the solder in. Apply lead-free solder all the way around the joint, allowing it to sweat into the seat joint.
  6. Remove the heat and allow the joint to cool.

Push-Connect Joints

  1. Cut the length of soft copper tubing with the circular tubing cutter. Remove any ridges formed by the cut from the inner wall of the tubing with the reamer.
  2. Chamfer the end of the tubing with the chamfering tool. Chamfering the tubing end reduces the possibility of gasket damage inside the press-connect joint, when inserting the copper tubing.
  3. Clean the chamfered end with 500-grit emery paper, to ensure that no sharp edges or nicks are present.
  4. Place the chamfered end of the soft copper tubing fully into the slot of the push-connector depth gauge that corresponds to the tubing outer diameter (O.D). Mark a line on the tubing with a metal scribe at the end of the gauge, to ensure the tubing will seat fully to the back of the connector fitting socket.
  5. Align the copper tube so that it is straight and in-line with the push-connector fitting.
  6. Apply a firm pushing and twisting motion, as the copper tubing enters the connector fitting. Push the copper tubing and fitting together -- until the tube is seated at the back of the fitting cup. Ensure the tubing is fully seated in the fitting up to the marked depth line.

Compression Coupler Fittings

  1. Cut the lengths of soft copper tubing, using the circular tubing cutter.
  2. Remove any ridges formed by the cut from the inner wall of the tubing with the reamer.
  3. Clean the end of the copper tubing with 500-grit emery paper.
  4. Slide a compression fitting nut onto one length of the tubing. The threaded open end of the nut must face the end of the tubing.
  5. Place a compression ring onto the tubing, in front of the open end threaded nut.
  6. Repeat Steps 3, 4 and 5 on the second length of copper tubing.
  7. Insert one end of the soft copper tubing into the end of the compression union fitting, until it is fully seated.
  8. Slide the compression ring, forward to the mouth of the union, followed by the nut. Hand-tighten the nut onto the union -- turning in a clockwise direction.
  9. Repeat Steps 7 and 8 on the second length of tubing.
  10. Tighten each of the compression fitting nuts -- clockwise, an additional one and a half turns -- using an adjustable wrench.

Things You Will Need

  • Circular tubing cutter
  • Reamer
  • Emery paper, 500-grit
  • Water-soluble soldering flux
  • Flux applicator brush
  • Propane torch
  • Lead-free solder
  • Chamfering tool
  • Push-connector depth gauge
  • Metal scribe
  • Adjustable wrench


  • Be aware of your surroundings when sweating copper tubing with a torch.
  • Wear safety glasses when soldering and avoid breathing fumes. Be sure to work with proper ventilation.
  • Always use lead-free solder on water pipes.

About the Author

Max Stout began writing in 2000 and started focusing primarily on non-fiction articles in 2008. Now retired, Stout writes technical articles with a focus on home improvement and maintenance. Previously, he has worked in the vocational trades such as automotive, home construction, residential plumbing and electric, and industrial wire and cable. Max also earned a degree of biblical metaphysician from Trinity Seminars Ministry Academy.