HDPE Pipe Pressure Rating Chart: PN10, PN16 & PN20

An HDPE pipe pressure rating describes the internal pressure the pipe is designed to withstand under specified material, temperature and service conditions. PN is commonly expressed in bar, while North American systems often use pressure rating in psi and DR. For North American projects, review the IPS PE4710 HDPE pipe requirements under ASTM D3035 and ASTM F714. The final allowable operating pressure must be confirmed against the applicable standard, material grade, temperature and project design conditions.

[Important: A PN number is not a universal pressure limit for every HDPE pipe. Material grade, SDR, operating temperature, fluid, surge pressure, fittings and the applicable standard must also be considered.]

HDPE Pipe Pressure Rating Chart

The Fundamentals of Pressure Rating

The pressure rating is the internal pressure assigned to a pipe under specified material, temperature, design and service conditions.

How PN, SDR and Material Grade Work Together

SDR describes pipe geometry rather than pressure by itself. Use the HDPE pipe specification and size table to compare outside diameter, wall thickness and SDR dimensions. For the same outside diameter and material grade, a lower SDR normally means a thicker wall and a higher pressure capability. The final PN or pressure rating must still be determined under the applicable standard and material design basis.

Common Pressure Rating Numbers

The typical pressure ratings for HDPE pipes range from PN6, which stands for “Pressure Nominal 6 bar,” to PN20, indicating a nominal pressure of 20 bars at 20°C. Other common ratings include:

• PN8
• PN10
• PN12.5
• PN16
• PN20

Deciphering the Numbers

The numbers in the pressure ratings correlate to the maximum operational pressures at 20°C/23℃, with the PN number indicating the pressure in bars. For example:

Temperature and Pressure Rating

It’s important to note that the pressure rating decreases as the temperature increases. Review the HDPE pipe temperature limits and environmental requirements before applying a de-rating factor. Manufacturers typically provide project-specific de-rating guidance for different operating temperatures.

Choosing the Right HDPE Pipe Pressure Rating for Your Project

1. Confirm the conveyed fluid and application.(For potable and municipal water projects, review the available HDPE water pipe specifications before selecting the pressure class.)
2. Confirm the applicable pipe standard and material grade.
3. Determine normal operating pressure and surge pressure.
4. Confirm operating temperature and required derating.
5. Select the SDR/PN or DR/PSI class.
6. Check fittings, joints, valves and flanges against the same design conditions.
7. Obtain final engineering approval.

For a visual aid, a chart could illustrate how pressure rating changes with temperature:

FAQ About HDPE Pipe Pressure Ratings

♦ Is PN16 always better than PN10?

Not always. PN16 represents a higher nominal pressure class, but under the same material grade and standard it normally requires a thicker pipe wall, which reduces the inside diameter and may increase cost. The appropriate choice depends on operating pressure, surge pressure, temperature, flow requirements, material grade and the applicable project standard.

♦ Can I choose an HDPE pipe pressure rating by diameter only?

No. Outside diameter alone does not determine the pressure rating. The selection must also consider SDR or DR, minimum wall thickness, material grade, operating temperature, applicable standard, surge conditions and the pressure capability of fittings and joints.

♦ Should fittings have the same pressure rating as the HDPE pipe?

Every fitting, valve, flange and joint must be compatible with the design pressure and operating conditions of the complete pipeline. The components may not always use the same pressure-class marking when different standards apply, but no component should reduce the allowable pressure of the finished system.

♦ What information should I provide when requesting a quotation?

Provide the application, conveyed fluid, pipe diameter, PN or SDR/DR, applicable standard, operating pressure, surge conditions, temperature, quantity, fitting list, destination and required certificates or project documents. If the pressure class has not been determined, provide the operating conditions for preliminary product selection and obtain final approval from the project engineer.

HDPE pipe pressure selection requires more than matching a PN number to an operating pressure. The applicable standard, material grade, SDR or DR, temperature, surge conditions and connected components must be reviewed together. Use the chart as a starting reference and confirm the final selection against the project specification.