HDPE Pipe Size FAQs

HDPE Pipe Size FAQs

1. What does HDPE pipe size mean?

HDPE pipe size typically refers to the outside diameter (OD) of the pipe. Common units include inches or millimeters, depending on regional standards. For example, a 110mm HDPE pipe has an outer diameter of 110mm.

2. What are the standard HDPE pipe sizes?

Standard HDPE pipe sizes vary by region, but commonly include:

Inches: 1/2", 3/4", 1", 2", 4", 6", 8", 10", 12", etc.

Millimeters: 20mm, 25mm, 32mm, 50mm, 63mm, 90mm, 110mm, 160mm, 200mm, 250mm, 315mm, 400mm, 500mm, 630mm, etc.

3. What is the difference between SDR 11 and SDR 17 HDPE pipe sizes?

The SDR (Standard Dimension Ratio) is the ratio of pipe outside diameter to wall thickness.

SDR 11 has a thicker wall and can handle higher pressure.

SDR 17 has a thinner wall and is used for lower-pressure systems.

Same diameter, different pressure ratings.

4. How do I choose the right HDPE pipe size?

Consider the following:

Flow rate requirements

Operating pressure

Length of the pipeline

Compatibility with fittings and system connections

Consulting with an engineer or supplier helps ensure correct sizing.

5. Is HDPE pipe size measured by ID or OD?

HDPE pipe is usually specified by its outside diameter (OD). This is especially important when ordering fittings or matching to standards like ASTM, ISO, or DIN.

6. What SDR ratings are available for HDPE pipes?

Common SDR ratings include: SDR 9, SDR 11, SDR 13.6, SDR 17, SDR 21, and SDR 26. Lower SDR = thicker pipe wall = higher pressure resistance.

7. Can I connect HDPE pipes of different SDRs or sizes?

Yes, but you must use the proper transition fittings or reducers designed for pressure balance and compatibility. Always consult with a qualified technician for mixed installations.

8. What's the largest size available for HDPE pipe?

HDPE pipes are manufactured in sizes up to 2000mm (about 78 inches) or more for large-scale municipal, industrial, and marine applications.

9. What’s the typical length of HDPE pipes?

Standard lengths include:

6 meters (20 feet)

12 meters (40 feet)

Coils for smaller diameters (20mm–110mm), often in 50m, 100m, or 200m rolls

10. Are HDPE pipe sizes compatible with other plastic pipe systems?

Not directly. HDPE sizing and joining methods (like butt fusion, electrofusion) differ from PVC or PPR pipes. Use transitional couplings when connecting different materials.

11. What is a DIPS Pipe?

DIPS stands for Ductile Iron Pipe Size.

DIPS pipes are sized based on the outside diameter (OD) of traditional ductile iron pipes. This sizing system is often used for HDPE, PVC, and ductile iron pipes in municipal water, sewer, and utility applications.

DIPS OD is larger than IPS (Iron Pipe Size)

Common for pipes 4 inches and above

Compatible with ductile iron fittings

What is a CTS Pipe?

CTS stands for Copper Tube Size.

CTS pipes follow the sizing system used for copper tubing, with the pipe size based roughly on the inside diameter (ID). Commonly used in plumbing, residential water supply, and smaller-diameter piping systems.

Typically used for pipes from 1/4" to 2"

Compatible with copper fittings and fixtures

Common in PEX, CPVC, and HDPE systems for homes

What is a SIDR Pipe?

SIDR stands for Standard Inside Dimension Ratio.

It’s a sizing system where the inside diameter (ID) stays proportional to the wall thickness. SIDR is often used with flexible HDPE pipes, especially in rural water, agriculture, and low-pressure systems.

SIDR-rated pipe is measured by ID

Joins using insert fittings and hose clamps (no fusion)

Typical SIDR values: SIDR 7, SIDR 9, SIDR 11.5, etc.

What are SDR and DR?

Both SDR (Standard Dimension Ratio) and DR (Dimension Ratio) refer to the ratio of the pipe’s outer diameter (OD) to its wall thickness.

SDR = OD ÷ Wall Thickness

Lower SDR = Thicker wall = Higher pressure capacity

Common SDR ratings: SDR 9, SDR 11, SDR 17, SDR 21, SDR 26

Used in HDPE, PVC, and other pressure-rated pipes

Example:

A 110mm SDR 11 pipe has a thicker wall than a 110mm SDR 17 pipe, so it can handle higher pressure.

What are OD and ID?

OD (Outside Diameter): The total outside width of the pipe.

Important for fittings and fusion in HDPE/PVC pipes

ID (Inside Diameter): The inner width (open space inside the pipe)

Determines flow capacity

In HDPE:

DIPS and IPS pipes are OD-based

SIDR pipes are ID-based