PVF Reference Library · Technical Reference

HDPE Pipe and SDR

HDPE pipe is sized by outside diameter and its wall is set by the dimension ratio (SDR or DR), the outside diameter divided by the minimum wall. This sheet covers SDR math, the IPS, DIPS and CTS sizing systems and the main fusion joining methods.

Ref PV-0010ASTM D3035ASTM F714AWWA C906

Draft, open for review. Check every value against the governing standard and the manufacturer’s data before use.

What it is

High-density polyethylene (HDPE) pipe is a flexible, corrosion-resistant thermoplastic pipe used for water, gas, sewer force mains, conduit and industrial lines. It is made to a controlled outside diameter. The wall thickness comes from the dimension ratio: SDR = average outside diameter ÷ minimum wall thickness. A lower SDR means a thicker wall. Small pipe is covered by ASTM D3035, larger pipe by ASTM F714, and potable water pipe by AWWA C906.

How to read it

The print line shows the nominal size, sizing system (IPS, DIPS or CTS), SDR or DR, material designation such as PE4710, standard, pressure class or rating and production code. Read the sizing system first. A 6 in IPS pipe and a 6 in DIPS pipe have different outside diameters and need different fittings.

Minimum wall by SDR (computed from IPS outside diameter)

SDR	4 in IPS, OD 4.500 in	6 in IPS, OD 6.625 in
7	0.643 in	0.946 in
9	0.500 in	0.736 in
11	0.409 in	0.602 in
13.5	0.333 in	0.491 in
17	0.265 in	0.390 in
21	0.214 in	0.315 in
26	0.173 in	0.255 in
32.5	0.138 in	0.204 in

Values are OD divided by SDR. Published tables may round slightly. Confirm against the governing standard.

Sizing systems

System	Outside diameter matches	Typical use
IPS	Steel pipe of the same NPS	Industrial, gas, general water
DIPS	Ductile iron pipe of the same size	Water mains tying into ductile iron
CTS	Copper tube of the same size	Small water and gas service lines

Key points

Pressure rating depends on SDR, material designation and temperature. Read it from the print line and the standard; do not calculate it at the counter.
Because SDR is a ratio, every size of the same SDR has the same pressure rating at the same conditions.
Butt fusion joins pipe ends with a heater plate. Electrofusion uses fittings with built-in heating coils. Socket fusion is used on small sizes. Sidewall fusion attaches saddles and branch outlets.
Mechanical fittings and compression couplings usually need an internal stiffener in HDPE.
Fusion parameters come from the pipe maker and the fusion machine procedure.

Common mistakes

Ordering fittings in IPS for a DIPS pipe.
Treating SDR as a size instead of a wall ratio.
Mixing SDRs in a butt fusion joint without a procedure that allows it.
Using a compression fitting without a stiffener.

Governing standards: ASTM D3035 (PE pipe, controlled OD); ASTM F714 (PE pipe, larger OD sizes); AWWA C906 (PE pressure pipe for water). Manufacturer fusion procedures.

Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.

More in Technical Reference

← All PVF sheets