HDPE pressure pipe is rated by its Dimension Ratio (DR) — the pipe's outside diameter divided by its minimum wall thickness. A lower DR means a thicker wall and a higher pressure rating.
What DR means
For PE4710 at 73°F (water), the pressure rating is PR = 2 × HDS ÷ (DR − 1), with HDS = 1,000 psi. That gives a clean ladder:
- DR 7 — 333 psi
- DR 9 — 250 psi
- DR 11 — 200 psi
- DR 13.5 — 160 psi
- DR 17 — 125 psi
- DR 21 — 100 psi
- DR 26 — 80 psi
Match the class to the service
Start with your operating pressure, add allowance for surge and a safety margin, then pick the DR whose rating comfortably exceeds it. For potable water mains, DR 11 (200 psi) and DR 13.5 (160 psi) are common; for low-pressure or reclaimed lines, DR 17–26 may be enough.
Don't forget temperature
Ratings are at 73°F. Above that, HDPE must be de-rated — the same DR carries less pressure at higher service temperatures.
Not sure which class fits? Send us your operating pressure and sizes and we'll confirm the right DR, or try the pipe finder on our HDPE pipe page.