PPI HDPE pipe design principles
HDPE pipe pressure rating is governed by the Dimension Ratio (DR = OD / t) and material Hydrostatic Design Basis (HDB): P = (2 × HDB × DF × FT) / (DR - 1).
PE4710 resins have an HDB of 1,600 psi at 73.4°F with a Design Factor (DF) of 0.63 for water, yielding higher pressure ratings than legacy PE3408/PE3608 resins (DF = 0.50).
Elevated operating temperatures derate pipe capacity according to PPI TR-9 temperature derating factors.
Worked example: 4" IPS DR 11 municipal water pipe
A 4" IPS pipe has an outside diameter of 4.500". At DR 11, minimum wall thickness is 4.500 / 11 = 0.409 inches.
For PE4710 resin at 73°F, the continuous working pressure rating is 201.6 psi (13.9 bar), with internal diameter of 3.633 inches.
HDPE pipe inputs
Dimension Ratio (DR)
Standard ratio of pipe outside diameter to minimum wall thickness (DR 7.3 to DR 26).
Material Grade
Select PE4710, PE3608, or PE2708 resin.
CALCULATOR QUESTIONS
HDPE pipe pressure rating & DR calculator questions
What does DR 11 mean in HDPE pipe?
DR 11 means the pipe outside diameter is exactly 11 times the minimum wall thickness, rated for 200 psi continuous water service in PE4710.
How does water temperature affect HDPE pipe rating?
Standard ratings apply up to 73.4°F (23°C). At 100°F (38°C) the rating is derated by 10%, at 120°F (49°C) by 22%, and at 140°F (60°C) by 37%.