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PEX-C pipe

Entry in PEX and plastic supply pipe · Updated · Written by the Know Your Pipes editors from the sources listed under References

PEX-C pipe is cross-linked polyethylene tubing produced by the electron-beam method: the polyethylene tube is extruded first and then exposed to a dose of high-energy electrons, which links its molecular chains.[1] Viega describes the same process as electron-beam irradiation after extrusion.[3]

Like the other types of PEX pipe, PEX-C is used for hot and cold water lines and heating. According to the Plastics Pipe Institute, the A, B and C labels describe only the process, not quality; tubing from each process has to pass the same ASTM F876 and CSA B137.5 requirements.[1]

1 How it differs

The three types differ in when and how the cross-links form. PEX-A is cross-linked by peroxides during extrusion, PEX-B by grafted silane that cures in moisture, and PEX-C by radiation once the tube has been formed.[1][2] For electron-beam tubing, ASTM F876 sets the permitted cross-link level at 65% minimum and 89% maximum, matching silane tubing.[2] Uponor, which makes PEX-A, gives 70% to 75% as typical for PEX-C and says PEX-C has less flexibility than PEX-A.[4] Viega says flexibility and handling vary by product.[3]

2 Fittings and repair

The manufacturing letter does not by itself decide which fittings fit.[3] Each tubing maker qualifies its tubing with particular fitting systems, such as crimp rings, clamps, press sleeves or push-fit fittings, and prints those standard numbers on the tubing.[1] Only the systems on the print line are approved for that tubing.

Uponor states that a kinked PEX-C tube cannot be restored with heat.[4] Viega's general advice for kinked PEX is to cut out the damaged length and install a fitting.[3]

3 Ratings

SDR 9 PEX tubing, whichever method made it, carries standard ratings of 160 psi for water at 73°F and 100 psi for water at 180°F; some products also carry an 80 psi rating at 200°F.[1] The maker's literature and the tubing's listing give the ratings for a specific product.[1] Daylight degrades PEX of every type, so PEX-C belongs indoors and covered until it is enclosed; the sunlight and UV limits entry has details.

See also

  • PEX pipeFlexible cross-linked polyethylene tubing for hot and cold water, rated 100 psi at 180°F and joined with mechanical fittings.
  • PEX-B pipePEX tubing cross-linked by the silane (moisture-cure) method; commonly joined with crimp, clamp, press or push-fit fittings.
  • PEX-A pipePEX tubing cross-linked by the peroxide (Engel) method during extrusion; the type used with cold-expansion fittings.
  • CPVC pipeRigid chlorinated PVC water pipe in copper tube sizes, rated 100 psi at 180°F and joined with CPVC solvent cement.
  • PP-R pipePolypropylene random-copolymer pressure pipe, joined by heat fusion, used for plumbing and hydronic systems mostly in larger buildings.
  • Polyethylene water service pipeFlexible black or colored PE tubing buried between the water main or well and the house; cold water only.

References

  1. Plastics Pipe Institute, "TN-17 Crosslinked Polyethylene (PEX) Pipe & Tubing Systems" (2021) — plasticpipe.org
  2. Plastics Pipe Institute, "Designing PEX Plumbing Systems to Optimize Performance and Efficiency" (2020) — conduitcalc.plasticpipe.org
  3. Viega, "PEX-A vs. PEX-B vs. PEX-C: Differences and Best Uses" (2026) — viega.us
  4. Uponor, "Not All PEX Is Created Equal: Why Choosing the Right Type Matters" (2025) — uponor.com