Copper Pipe vs. PEX Tubing
Comparing 2 standards across 14 specifications. 14 key differences identified.
Seamless copper water tubing is standardized under ASTM B88 into three primary wall thickness grades: Type K (Green / Heavy Wall for underground mains), Type L (Blue / Medium Wall for standard interior residential plumbing), and Type M (Red / Thin Wall for low-pressure hydronic heating). All three types share identical outer diameters for standard solder, flare, and press fittings.
Cross-linked Polyethylene (PEX) is flexible plastic potable water and radiant heating tubing standardized under ASTM F876 and F877. Classified by cross-linking manufacturing chemistry into PEX-A (Engel cold expansion), PEX-B (Silane crimp/clamp), and PEX-C (Radiation), PEX adheres to Copper Tube Size (CTS) outer dimensions with SDR-9 pressure ratings.
Specification Comparison Table
14 Parameters| Parameter / Spec | ||
|---|---|---|
|
Governing Standard
|
ASTM B88 / NSF 61 | — |
|
Type K (Green Stripe)
|
Heavy wall: 1/2" = 0.049" (1.24 mm) | 3/4" = 0.065" (1.65 mm) wall | — |
|
Type L (Blue Stripe)
|
Medium wall: 1/2" = 0.040" (1.02 mm) | 3/4" = 0.045" (1.14 mm) wall | — |
|
Type M (Red Stripe)
|
Thin wall: 1/2" = 0.028" (0.71 mm) | 3/4" = 0.032" (0.81 mm) wall | — |
|
Outer Diameter Formula (CTS)
|
Actual OD = Nominal Size + 1/8 inch (0.125") | — |
|
Joining Methods
|
Capillary solder (sweat), ProPress copper crimp, flare, compression | — |
|
Operating Temperature
|
Up to 400°F (204°C) continuous in hydronic heating | — |
|
Governing Standards
|
— | ASTM F876 / ASTM F877 / CSA B137.5 / NSF 61 / NSF 14 |
|
Standard Dimension Ratio
|
— | SDR-9 (OD to wall thickness ratio = 9:1) |
|
PEX-A (Engel Method)
|
— | >85% cross-linking | Extreme flexibility & thermal shape memory (ASTM F1960) |
|
PEX-B (Silane Method)
|
— | 65–70% cross-linking | High chlorine resistance (ASTM F1807 / F2159) |
|
PEX-C (Electron Beam)
|
— | 60–65% cross-linking | Eco-friendly manufacturing process |
|
Pressure Ratings
|
— | 160 PSI @ 73.4°F (23°C) | 100 PSI @ 180°F (82°C) | 80 PSI @ 200°F (93°C) |
|
Bend Radius Minimum
|
— | 6× outer diameter (PEX-A can bend tighter to 5× OD) |