PEX · grade
PEX EVOH
Properties of the EVOH condition, compared with the other PEX grades.
PEX with an EVOH oxygen-diffusion barrier per DIN 4726 — mandatory for closed hydronic/radiant loops with ferrous boilers, pumps or manifolds.
What is PEX EVOH?
PEX EVOH is PEX in the EVOH grade — pEX with an EVOH oxygen-diffusion barrier per DIN 4726 — mandatory for closed hydronic/radiant loops with ferrous boilers, pumps or manifolds. PEX EVOH has a yield strength of 19 MPa (2.76 ksi) and a tensile strength of 24 MPa (3.48 ksi) — weaker than 86% of polymer grades. Elongation at break is 500% and the elastic modulus is 0.68 GPa (0.0986 Msi). PEX EVOH has a density of 0.94 g/cm³ (0.034 lb/in³), lighter than 76% of polymer grades. Its glass-transition temperature is -120°C (-184 °F). PEX-A is the default condition FabDigit quotes; EVOH is available on request or by drawing note.
Advantages
- Low moisture uptake — 0.01%, better than 97% of polymer grades
- Conducts heat well — 0.4 W/m·K (0.231 BTU/hr·ft·°F), better than 93% of polymer grades
- Forms and bends easily — 90/100, better than 92% of polymer grades
- Low embodied carbon — 2.3 kg CO₂/kg, better than 92% of polymer grades
- Good corrosion resistance — 92/100, better than 91% of polymer grades
Limitations
- Hard to polish — 25/100, worse than 90% of polymer grades
- High mold shrinkage — 2.2%, worse than 88% of polymer grades
- Low strength — 19 MPa (2.76 ksi), worse than 86% of polymer grades
- Difficult to weld — 10/100, worse than 84% of polymer grades
- Difficult to machine — 45/100, worse than 77% of polymer grades
PEX EVOH properties
Typical room-temperature values for PEX EVOH — 3 properties are specific to this condition; the rest are grade-level values shared by every PEX grade. Each bar shows where the value sits among the polymer grades in FabDigit's library — further right is higher.
Physical5
PEX EVOH has a density of 0.94 g/cm³ (0.034 lb/in³), lighter than 76% of polymer grades. Its glass-transition temperature is -120°C (-184 °F).
Mechanical10
PEX EVOH has a yield strength of 19 MPa (2.76 ksi) and a tensile strength of 24 MPa (3.48 ksi) — weaker than 86% of polymer grades. Elongation at break is 500% and the elastic modulus is 0.68 GPa (0.0986 Msi).
Thermal11
PEX EVOH is rated for continuous service to 95°C (203 °F). It conducts heat at 0.4 W/m·K (0.231 BTU/hr·ft·°F), better than 93% of polymer grades. Thermal expansion is 170 µm/m·K (94.4 µin/in·°F).
Electrical7
PEX EVOH is an electrical insulator with a dielectric strength of 25 kV/mm (635 V/mil) and a resistivity of 1×10¹⁴ Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (92/100), better than 91% of polymer grades. UV resistance is poor.
Sustainability4
Producing a kilogram of PEX EVOH takes about 82 MJ of energy and emits 2.3 kg of CO₂ — less than 83% of polymer grades. Typical recycled content is 0%.
Manufacturability8
PEX EVOH's machinability is fair (45/100, worse than 77% of polymer grades); weldability not recommended (10/100); formability excellent (90/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other PEX grades and fills
PEX is also supplied in 10 other conditions. The full side-by-side table is on the PEX overview.
- PEX-ADefaultHighest and most uniform cross-link density with thermal shape memory — choose for expansion (cold-expansion) fittings, tight bends and kink repair by heating.22 MPa tensile
- XLPE-CABLEUltra-clean peroxide-curable PE compound for 0.6/1 kV to 500 kV cable insulation — 90 °C continuous, 250 °C short-circuit rating.20 MPa tensile
- EVOHPEX with an EVOH oxygen-diffusion barrier per DIN 4726 — mandatory for closed hydronic/radiant loops with ferrous boilers, pumps or manifolds.24 MPa tensile
Working with PEX EVOH
Is PEX easy to machine?
Cuts cleanly with a tubing cutter or sharp knife; milling/turning is possible but gummy — use sharp positive-rake tools, high speed, low feed and air cooling.
Can PEX be welded?
Cannot be heat-fused or solvent-cemented once cross-linked; join with cold-expansion (PEX-a), copper-crimp, stainless-clamp or push-fit fittings, or use electrofusion only on the uncrosslinked skin of specialty products.
Can PEX be formed, bent or molded?
Extruded and cross-linked in-line (Engel/Sioplas) or post-irradiated; PEX-a can be reformed and shrunk back with a heat gun (shape memory), other types bend cold to ~6–8× OD with support bends.
What surface finishes work on PEX?
No paint or plating adheres without corona/flame treatment; surfaces are matte and colour is provided by masterbatch (red/blue/white/black) rather than coating.
PEX chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| peroxide crosslinker (DCP)PEX-a and XLPE cable grades only | 0.5 – 2.5 | 1.5 |
| vinyl silane + catalystPEX-b (Sioplas/Monosil) route | 1 – 2.5 | 1.8 |
| antioxidant / thermal stabilizerhindered phenol + phosphite; chlorine resistance package for potable water | 0.1 – 0.6 | 0.3 |
| UV stabilizer / carbon blackUV-stabilized variants only | 0 – 2.5 | 0 |
| gel content (degree of crosslinking)ASTM D2765 / ISO 15875-2: PEX-a ≥70%, PEX-b ≥65%, PEX-c ≥60% | 60 – 89 | 72 |
| ethylene (PE base resin)HDPE/MDPE base, density 0.94–0.95 before crosslinking | ≥ 95 (balance) | — |
PEX EVOH — frequently asked
What is PEX EVOH used for?
PEX EVOH is typically used for radiant floor heating tubing, potable water plumbing, hydronic piping and insulated cable jacketing. In short: cross-linked, not fusible; hot-water rated polyethylene; PEX-a shape memory.
What is the yield strength of PEX EVOH?
PEX EVOH has a typical yield strength of 19 MPa (2.76 ksi) and a tensile strength of 24 MPa (3.48 ksi) — weaker than 86% of polymer grades. Strength varies by condition: see the 11 listed tempers.
Is PEX EVOH easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 77% of polymer grades). Cuts cleanly with a tubing cutter or sharp knife; milling/turning is possible but gummy — use sharp positive-rake tools, high speed, low feed and air cooling.
Can PEX EVOH be welded?
Not readily — weldability is rated not recommended (10/100). Cannot be heat-fused or solvent-cemented once cross-linked; join with cold-expansion (PEX-a), copper-crimp, stainless-clamp or push-fit fittings, or use electrofusion only on the uncrosslinked skin of specialty products.
What surface finishes work on PEX EVOH?
No paint or plating adheres without corona/flame treatment; surfaces are matte and colour is provided by masterbatch (red/blue/white/black) rather than coating.
Can PEX EVOH be formed, bent or molded?
Extruded and cross-linked in-line (Engel/Sioplas) or post-irradiated; PEX-a can be reformed and shrunk back with a heat gun (shape memory), other types bend cold to ~6–8× OD with support bends.
What is the maximum service temperature of PEX EVOH?
PEX EVOH is rated for continuous use to about 95°C (203 °F), and briefly to 110°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM F876 — Crosslinked Polyethylene (PEX) Tubing — ASTM International (2023)
- ISO 15875-1/-2 — Plastics piping systems for hot and cold water installations, Crosslinked polyethylene (PE-X) — ISO (2018)
- ASTM D2765 — Degree of Crosslinking (Gel Content) in Crosslinked Ethylene Plastics — ASTM International (2016)
- ASTM F2023 — Oxidative Resistance of PEX Tubing to Hot Chlorinated Water — ASTM International (2020)
- IEC 60502-1/-2 — Power cables with extruded XLPE insulation — IEC (2021)
- Crosslinkable PE pipe and cable compound datasheets (Borealis/Borouge, Uponor, Rehau, Wanhua) — various producers (2024)
- Engineered Materials Handbook Vol. 2: Engineering Plastics — ASM International (1988)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.