How to Connect Pex

Since its introduction into the U.

PEX connections do not require solder or glue.PEX connections do not require solder or glue.
S. plumbing market in the 1980s, cross-linked polyethylene pipe (PEX) has gained wide acceptance as a viable alternative to copper tubing. PEX has a long life expectancy and high temperature and pressure ratings. PEX is flexible and resists freezing. The tubing also resists encrustation, thus eliminating mineral or lime build up. Because it can be installed in long runs and turn 90-degree corners, PEX installations require up to 50 percent fewer fittings when compared to rigid pipe installations. Additionally, installation time is reduced because PEX fittings do not require solder or glue.

Join PEX to PEX by placing a copper crimp ring around one of the tubes and inserting a crimp style adapter into the end. Position the crimp ring halfway along the ribbed portion of the adapter. Place the PEX crimping tool jaws squarely over the ring and squeeze the handles together. Repeat by joining the second tube to the other end of the adapter.

Use the special go/no-go gauge to check both connections. If the go slot fits snugly over the crimp rings and the no-go slot does not, the connection is sound.

Make compression connections using PEX 3-part fittings to connect PEX tubing to a manifold or other component. Slide the brass nut onto the PEX with the threaded portion facing the end of the tube. Slide the ferrule over the end, and insert the adapter shaft into the PEX. Thread the nut onto the manifold and tighten.

Complete a push-fit connection by first making a square, clean cut on the end of the tubing with a specially designed PEX tubing cutter. This tool resembles a pair of pruning shears. Insert a support sleeve into the cut end of the PEX to prevent the tube from collapsing.

Measure the manufacturer's recommended insertion distance from the end of the PEX with a ruler. Mark with a fine felt-tipped pen. Grasp the PEX push-fit connector with one hand and press the cut and reinforced end of the tubing into the connector until it encounters resistance. Check that the flange lines up with the pen mark on the PEX. Repeat with the second piece of tubing.

Make expansion connections using a special expander tool together with Pro-PEX fittings, and PEX-a high grade tubing. A 1/2-inch Pro-Pex fitting will not fit into 1/2-inch PEX-a tubing. To maintain the same bore diameter throughout the joint, an expansion joint is necessary.

Fit a Pro-PEX expander ring over the end of the tubing with the end of the expander ring protruding 1/8 inch off the end of the PEX-a high grade tubing. Screw the correct size head onto the expander tool. Slide the tapered end of the head into the tubing and bring the handles of the expander together. Repeat between five and 15 times while rotating the tubing on the expander head.

Remove the tool and quickly slide the Pro-PEX fitting into the tubing. The PEX-a high grade tubing will try to shrink back to its original size and form a pressure tight seal around the Pro-PEX fitting.

Things You Will Need

  • PEX tubing
  • Copper crimp ring
  • Crimp style adapter
  • PEX crimping tool
  • Go/no-go gauge
  • 3-part compression fitting
  • PEX tubing cutter
  • PEX support sleeve
  • Ruler
  • Fine felt-tipped pen
  • PEX push-fit connector
  • Special expander tool
  • Pro-PEX fittings
  • PEX-a high grade tubing
  • Pro-PEX expander ring


  • If you are installing a manifold, use blue PEX for cold-water plumbing and red PEX for hot-water plumbing. This will save time during later maintenance procedures.


  • Use oxygen barrier PEX or PEX-A-PEX when connecting to equipment containing ferrous (iron-based) metal to prevent the material from rusting.
  • Do not expose PEX tubing to sunlight for extended periods. The tubing will deteriorate when exposed to UV radiation.

About the Author

After graduating from the University of the Witwatersrand and qualifying as an aircraft engineer, Ian Kelly joined a Kitchen remodeling company and qualified as a Certified Kitchen Designer (CKD). Kelly then established an organization specializing in home improvement, including repair and maintenance of household appliances, garden equipment and lawn mowers.