NPS (Nominal Pipe Size) is a dimensionless ordinal number used to indicate the size of a pipe. The number following NPS indicates the size of the standard pipe. The NPS system originated from the IPS (Iron Pipe Size) system, which was introduced to distinguish different pipe sizes. These sizes were originally in inches and represented the approximate inside diameter of the pipe. For example, a pipe marked as IPS 6" has an inner diameter of approximately 6 inches.
For carbon steel pipe wall thickness, there are 10 grades: Sch10, 20, 30, 40, 60, 80, 100, 120, 140, 160
NPS | DN |
Tube OD. |
SCH5s | SCH10s | SCH10 | SCH20 | SCH30 | STD | SCH40 | SCH40s |
1/2" | 15 | 21.3 | 1.65 | 2.11 | 2.11 |
|
2.41 | 2.77 | 2.77 | 2.77 |
3/4" | 20 | 26.7 | 1.65 | 2.11 | 2.11 |
|
2.41 | 2.87 | 2.87 | 2.87 |
1" | 25 | 33.4 | 1.65 | 2.77 | 2.77 |
|
2.9 | 3.38 | 3.38 | 3.38 |
1-1/4" | 32 | 42.2 | 1.65 | 2.77 | 2.77 |
|
2.97 | 3.56 | 3.56 | 3.56 |
1-1/2" | 40 | 48.3 | 1.65 | 2.77 | 2.77 |
|
3.18 | 3.68 | 3.68 | 3.68 |
2" | 50 | 60.3 | 1.65 | 2.77 | 2.77 |
|
3.18 | 3.91 | 3.91 | 3.91 |
2-1/2" | 65 | 73 | 2.11 | 3.05 | 3.05 |
|
4.78 | 5.16 | 5.16 | 5.16 |
3" | 80 | 88.9 | 2.11 | 3.05 | 3.05 |
|
4.78 | 5.49 | 5.49 | 5.49 |
3-1/2" | 90 | 101.6 | 2.11 | 3.05 | 3.05 |
|
4.78 | 5.74 | 5.74 | 5.74 |
4" | 100 | 114.3 | 2.11 | 3.05 | 3.05 |
|
4.78 | 6.02 | 6.02 | 6.02 |
5" | 125 | 141.3 | 2.77 | 3.4 | 3.4 |
|
|
6.55 | 6.55 | 6.55 |
6" | 150 | 168.3 | 2.77 | 3.4 | 3.4 |
|
|
7.11 | 7.11 | 7.11 |
8" | 200 | 219.1 | 2.77 | 3.76 | 3.76 | 6.35 | 7.04 | 8.18 | 8.18 | 8.18 |
10" | 250 | 273 | 3.40 | 4.19 | 4.19 | 6.35 | 7.8 | 9.27 | 9.27 | 9.27 |
12" | 300 | 323.8 | 3.96 | 4.57 | 4.57 | 6.35 | 8.38 | 9.53 | 10.31 | 9.53 |
14" | 350 | 355.6 | 3.96 | 4.78 | 6.35 | 7.92 | 9.53 | 9.53 | 11.13 |
|
16" | 400 | 406.4 | 4.19 | 4.78 | 6.35 | 7.92 | 9.53 | 9.53 | 12.7 |
|
18" | 450 | 457.2 | 4.19 | 4.78 | 6.35 | 7.92 | 11.13 | 9.53 | 14.27 |
|
20" | 500 | 508 | 4.78 | 5.54 | 6.35 | 9.53 | 12.7 | 9.53 | 15.09 |
|
22" | 550 | 558.8 | 4.78 | 5.54 | 6.35 | 9.53 | 12.7 | 9.53 |
|
|
24" | 600 | 609.6 | 5.54 | 6.35 | 6.35 | 9.53 | 14.27 | 9.53 | 17.48 |
|
26" | 650 | 660.4 |
|
|
7.92 | 12.7 |
|
9.53 |
|
|
28" | 700 | 711.2 |
|
|
7.92 | 12.7 | 15.88 | 9.53 |
|
|
30" | 750 | 762 | 6.35 | 7.92 | 7.92 | 12.7 | 15.88 | 9.53 |
|
|
32" | 800 | 812.8 |
|
|
7.92 | 12.7 | 15.88 | 9.53 | 17.48 |
|
34" | 850 | 863.6 |
|
|
7.92 | 12.7 | 15.88 | 9.53 | 17.48 |
|
36" | 900 | 914.4 |
|
|
7.92 | 12.7 | 15.88 | 9.53 | 19.05 |
|
38" | 950 | 965.2 |
|
|
|
|
|
9.53 |
|
|
40" | 1000 | 1016 |
|
|
|
|
|
9.53 |
|
|
42" | 1050 | 1066.8 |
|
|
|
|
|
9.53 |
|
|
44" | 1100 | 1117.6 |
|
|
|
|
|
9.53 |
|
|
46" | 1150 | 1168.4 |
|
|
|
|
|
9.53 |
|
|
48" | 1200 | 1219.2 |
|
|
|
|
|
9.53 |
|
The wall thickness grades of stainless steel pipes are 5S, 10S, 40S and 80S. Stainless steel pipes are widely used and are often used in industrial fields with high corrosion requirements.
The SCH series of pipe wall thickness grades provides a standardized way to indicate the wall thickness of steel pipes of different specifications. This system originated from the American steel pipe standard and is widely used in pipeline projects around the world. NPS (nominal size) is used to identify the specifications of the pipe, while SCH is used to indicate the wall thickness of the pipe. Understanding the basic concepts of SCH and NPS is essential for selecting the appropriate pipe type and wall thickness. In practical applications, according to different pipe standards, pressure levels and use environments, selecting the appropriate SCH level can ensure the safety and reliability of the pipeline system.