HDPE Thermoplastic pipe sizes IPS DIPS mm Chart Conversion

HDPE: High density polyethylene (HDPE) refers to the thermoplastic polymer produced from the monomer ethylene. HDPE piping has a high strength-to-density ratio and highly bendable, allowing for pipe to be coiled. HDPE is lightweight, flexible, inexpensive and corrosion resistant. In addition to piping, HDPE is used in the production of plastic bottles, geomembranes, grocery bags, toys, containers and plastic lumber.

IPS and DIPS: Iron Pipe Size or IPS represents the nominal diameter of the pipe. A 6-in. IPS pipe has an inside diameter of six inches. Ductile Iron Pipe Size or DIPS is used to specify the size of ductile iron pipe. Typically, IPS refers to black iron or carbon steel pipe while DIPS refers to cast/ductile iron pipe. IPS and DIPS are used in the HDPE market to replicate the familiar dimensions of these other IPS pipe is available in size ranging from ¾-in. to 65-in. diameters while DIPS is available from 4- in. to 36-in. diameters.

CTS: Copper Tube Size is specific to plumbing and potable water systems. In copper, the OD is always 1/8 inch larger that the nominal size of the pipe, and that has carried over to HPDE that is built to CTS sizes. As a replacement for traditional copper lines for water, a 2-in. HDPE pipe that follows CTS sizing standards would have an OD of 2 1/8 in. For water applications HDPE pipe can be sized as small as ¾ in OD.

Bend Radius: Bend radius, measured to the inside curvature, is the minimum radius one can bend a pipe, tube, sheet, cable or hose without kinking it, damaging it or shortening its life. The smaller the bend radius, the greater is the material flexibility. HDPE piping is more flexible than other competitive piping options, offering a smaller bend radius. However, exceeding minimum bend radiuses may result in mechanical failure and decreased longevity. And for HDPE-encased fiber-optic cabling, it is problematic, as exceeding minimum bend radius can cause light attenuation resulting in performance loss.  

Dimension Ratio (DR): The Dimension Ratio (DR) is the ratio of the pipe outside diameter to the pipe minimum wall thickness. As diameters change, the pressure rating remains the same for the same material, dimension ratio and application.

Certain Dimension Rations (DRs) that meet an ASTM International specified number series (32.5, 26, 21, 17, 13.5) are referred to as Standard Dimension Ratios (SDRs). There is approximately 25% difference in minimum wall thickness between each SDR.

Calculating SDR: SDR is defined as the ratio of the nominal outside diameter to the nominal wall thickness.

 Where dn is the nominal outside diameter of pipe and en is the nominal (minimum) wall thickness of the pipe.

Carbon Black (CB): Carbon Black products are additives used to improve the strength and performance of HDPE pipe. CBs are typically used to improve UV resistance and to reduce or lower moisture absorption in pipe

Coefficient of friction: Coefficient of friction measures the amount of friction existing between two surfaces. As this measurement relates to piping, a lower coefficient of friction typically means less friction damage in piping (example: outer layer wear). To find the coefficient of friction (fr) use this formula: