Steel pipe table ASME B36.10: outside diameter, wall and inside diameter (Sch 40 and 80)
Outside diameter, wall thickness and inside diameter of steel pipe from 1/2" to 12" in schedules 40 and 80, per ASME B36.10M, in millimetres.
The outside diameter is fixed for each nominal size (NPS). The schedule sets the wall thickness and, with it, the inside diameter, which is what matters for velocity and pressure drop.
| NPS (in) | DN | Outside diameter | Wall Sch 40 | Inside diameter Sch 40 | Wall Sch 80 | Inside diameter Sch 80 |
|---|---|---|---|---|---|---|
| 1/2" | 15 | 21.34 | 2.77 | 15.80 | 3.73 | 13.88 |
| 3/4" | 20 | 26.67 | 2.87 | 20.93 | 3.91 | 18.85 |
| 1" | 25 | 33.40 | 3.38 | 26.64 | 4.55 | 24.30 |
| 1 1/4" | 32 | 42.16 | 3.56 | 35.04 | 4.85 | 32.46 |
| 1 1/2" | 40 | 48.26 | 3.68 | 40.90 | 5.08 | 38.10 |
| 2" | 50 | 60.33 | 3.91 | 52.51 | 5.54 | 49.25 |
| 2 1/2" | 65 | 73.03 | 5.16 | 62.71 | 7.01 | 59.01 |
| 3" | 80 | 88.90 | 5.49 | 77.92 | 7.62 | 73.66 |
| 4" | 100 | 114.30 | 6.02 | 102.26 | 8.56 | 97.18 |
| 6" | 150 | 168.28 | 7.11 | 154.06 | 10.97 | 146.34 |
| 8" | 200 | 219.08 | 8.18 | 202.72 | 12.70 | 193.68 |
| 10" | 250 | 273.05 | 9.27 | 254.51 | 15.09 | 242.87 |
| 12" | 300 | 323.85 | 10.31 | 303.23 | 17.48 | 288.89 |
Nominal dimensions: the standard allows manufacturing tolerances. Other schedules (10, STD, XS, 160) and the stainless pipes of ASME B36.19M are not in the table.
Values calculated from the reference functions; they do not replace measurement or a calibration certificate.