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HDPE Thermoplastic pipe sizes IPS DIPS mm Chart Conversion

HDPE Thermoplastic pipe sizes IPS DIPS mm Chart Conversion

Jan 6,2023
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.

Standard Dimension Ratio (SDR):

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.

SDR = dn/en

 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:
IPS PIPE SIZES (INCHES) – (Iron Pipe Size based)
Iron pipe size, or IPS, is the original pipe sizing system from the early 19th century. IPS is still the predominant sizing system used in most industries including oil and gas gathering, gas distribution, mining, and some potable water and wastewater applications in the United States.
American Standard Size
Nominal Pipe Size IPS (Known as Inches)
Real Size Outside Diameter (OD)
(Inches)
Real Outside Diameter (OD)
(mm) 1 Inch = 25,4 mm
Closer Metric Pipe size or
(mm) (Not the same)
1/2″ IPS 0,84″ 21,34 mm 20 mm
3/4″ IPS 1,05″ 26,67 mm 25 mm
1″ IPS 1,32″ 33,40 mm 32 mm
1-1/4″ IPS 1,66″ 42,16 mm 40 mm
1-1/2″ IPS 1,90″ 48,26 mm 50 mm
2″ IPS 2,38″ 60,33 mm 63 mm
2-1/2″ IPS 2,87″ 72,90 mm 75 mm
3″ IPS 3,50″ 88,90 mm 90 mm
4″ IPS 4,50″ 114,30 mm 110 mm
5″ IPS 5,56″ 141,22 mm 140 mm
6″ IPS 6,63″ 168,28 mm 160 mm
7″ IPS 7,13″ 180,98 mm 180 mm
8″ IPS 8,63″ 219,08 mm 200 mm
10″ IPS 10,75″ 273,05 mm 250 mm
12″ IPS 12,75″ 323,85 mm 315 mm
14″ IPS 14,00″ 355,60 mm 355 mm
16″ IPS 16,00″ 406,40 mm 400 mm
18″ IPS 18,00″ 457,20 mm 450 mm
20″ IPS 20,00″ 508,00 mm 500 mm
22″ IPS 22,00″ 558,80 mm 550 mm
24″ IPS 24,00″ 609,60 mm 600 mm
25″ IPS 25,00″ 630,00 mm 630 mm
28″ IPS 28,00″ 711,20 mm 700 mm
30″ IPS 30,00″ 762,00 mm 750 mm
32″ IPS 32,00″ 812,80 mm 800 mm
36″ IPS 36,00″ 914,40 mm 900 mm
42″ IPS 42,00″ 1066,80 mm 1000 mm
48″ IPS 48,00″ 1219,20 mm 1200 mm
DIPS PIPE SIZES (INCHES) – (Ductile Iron Pipe Size based)

Ductile iron pipe size, or DIPS, was created in 1948 when iron pipe wall thicknesses were more controllable and a required inside diameter (ID) could be maintained. The DIPS pipe sizing system is the predominant sizing system used in potable water and sewer applications still today.
Nominal Pipe Size DIPS (Known as Inches) Real Size Outside Diameter (OD)
(Inches)
Real Outside Diameter (OD) (mm) 1 Inch = 25.4 mm
3″ DIPS 3,96 in. 100.584 mm
4″ DIPS 4.8 in. 121.92 mm
6″ DIPS 6.9 in. 175.26 mm
8″ DIPS 9.05 in. 229.87 mm
10″ DIPS 11.1 in. 281.94 mm
12″ DIPS 13.2 in. 335.28 mm
14″ DIPS 15.3 in. 388.62 mm
16″ DIPS 17.4 in. 441.96 mm
18″ DIPS 19.5 in. 495.3 mm
20″ DIPS 21.6 in. 548.64 mm
24″ DIPS 25.8 in. 655.32 mm
30″ DIPS 32 in. 812.8 mm
36″ DIPS 38.3 in. 972.82 mm
42″ DIPS 44.5 in. 1130.3 mm
48″ DIPS 50.8 in. 1290.32 mm
METRIC PIPE SIZES (mm) – (European sizes)
mm Pipe DN
Nominal Diameter
mm OD
Outside Diameter
Closer Inches IPS Pipe size (NOT THE SAME)
20 mm 20.3 mm 1/2″ IPS = 21.34 mm
25 mm 25.3 mm 3/4″ IPS = 26.67 mm
32 mm 32.3 mm 1″ IPS = 33.40 mm
40 mm 40.4 mm 1-1/4″ IPS = 42.16 mm
50 mm 50.5 mm 1-1/2″ IPS = 48.26 mm
63 mm 63.4 mm 2″ IPS = 60.33 mm
75 mm 75.5 mm 2-1/2″ IPS = 72.90 mm
90 mm 90.6 mm 3″ IPS = 88.90 mm
110 mm 110.7 mm 4″ IPS = 114.30 mm
140 mm 140.9 mm 5″ IPS = 141.22 mm
160 mm 161 mm 6″ IPS = 168.28 mm
180 mm 181.1 mm 7″ IPS = 180.98 mm
200 mm 201.2 mm 8″ IPS = 219.08 mm
250 mm 249.7 mm 10″ IPS = 273.05 mm
315 mm 314.6 mm 12″ IPS = 323.85 mm
355 mm 354.2 mm 14″ IPS = 355.60 mm
400 mm 399.3 mm 16″ IPS = 406.40 mm
450 mm 449.9 mm 18″ IPS = 457.20 mm
500 mm 499.4 mm 20″ IPS = 508.00 mm
550 mm 563.4 mm 22″ IPS = 558.80 mm
600 mm 629.2 mm 24″ IPS = 609.60 mm
630 mm 633.8 mm 25″ IPS = 630.00 mm
700 mm  28″ IPS = 711.20 mm
750 mm  30″ IPS = 762.00 mm
800 mm 807.2 mm 32″ IPS = 812.80 mm
900 mm 908.1 mm 36″ IPS = 914.40 mm
1000 mm 1009.0 mm 42″ IPS = 1066.80 mm
1200 mm  48″ IPS = 1219.20 mm
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