I. Table of Common Sizes for Seamless Steel Pipes
| Nominal Diameter DN | NPS | Outside Diameter OD (mm) | SCH 10 (mm) | SCH 20 (mm) | SCH 40 / STD (mm) | SCH 60 (mm) | SCH 80 / XS (mm) | SCH 100 (mm) | SCH 120 (mm) | SCH 160 (mm) |
|---|---|---|---|---|---|---|---|---|---|---|
| 15 | 1/2″ | 21.3 | 2.11 | — | 2.77 | — | 3.73 | — | — | 4.78 |
| 20 | 3/4″ | 26.7 | 2.11 | — | 2.87 | — | 3.91 | — | — | 5.56 |
| 25 | 1″ | 33.4 | 2.77 | — | 3.38 | — | 4.55 | — | — | 6.35 |
| 32 | 1-1/4″ | 42.2 | 2.77 | — | 3.56 | — | 4.85 | — | — | 6.35 |
| 40 | 1-1/2″ | 48.3 | 2.77 | — | 3.68 | — | 5.08 | — | — | 7.14 |
| 50 | 2″ | 60.3 | 2.77 | — | 3.91 | — | 5.54 | — | — | 8.74 |
| 65 | 2-1/2″ | 73.0 | 3.05 | — | 5.16 | — | 7.01 | — | — | 9.53 |
| 80 | 3″ | 88.9 | 3.05 | — | 5.49 | — | 7.62 | — | — | 11.13 |
| 90 | 3-1/2″ | 101.6 | 3.05 | — | 5.74 | — | 8.08 | — | — | 12.70 |
| 100 | 4″ | 114.3 | 3.05 | — | 6.02 | — | 8.56 | 11.13 | — | 13.49 |
| 125 | 5″ | 141.3 | 3.40 | — | 6.55 | — | 9.53 | 12.70 | — | 15.88 |
| 150 | 6″ | 168.3 | 3.40 | — | 7.11 | — | 10.97 | 14.27 | — | 18.26 |
| 200 | 8″ | 219.1 | 3.76 | 6.35 | 8.18 | 10.31 | 12.70 | 15.09 | 18.26 | 23.01 |
| 250 | 10″ | 273.0 | 4.19 | 6.35 | 9.27 | 12.70 | 15.09 | 18.26 | 21.44 | 28.58 |
| 300 | 12″ | 323.9 | 4.57 | 6.35 | 10.31 | 14.27 | 17.48 | 21.44 | 25.40 | 33.32 |
| 350 | 14″ | 355.6 | 6.35 | 7.92 | 11.13 | 15.09 | 19.05 | 23.83 | 27.79 | 35.71 |
| 400 | 16″ | 406.4 | 6.35 | 7.92 | 12.70 | 16.66 | 21.44 | 26.19 | 30.96 | 40.49 |
| 450 | 18″ | 457.0 | 6.35 | 7.92 | 14.27 | 19.05 | 23.83 | 29.36 | 34.93 | 46.24 |
| 500 | 20″ | 508.0 | 6.35 | 9.53 | 15.09 | 20.62 | 26.19 | 32.54 | 38.10 | 50.01 |
| 550 | 22″ | 559.0 | 6.35 | 9.53 | 15.88 | 22.23 | 28.58 | 34.93 | 41.28 | 53.97 |
| 600 | 24″ | 610.0 | 6.35 | 9.53 | 17.45 | 24.61 | 30.96 | 38.89 | 46.02 | 59.54 |
2. Common Seamless Steel Pipe Specifications
In actual purchasing, seamless steel pipes are typically specified as:
Outside Diameter × Wall Thickness × Length
For example:
- Φ48.3 × 3.68 mm
- Φ60.3 × 3.91 mm
- Φ114.3 × 6.02 mm
- Φ168.3 × 7.11 mm
- Φ219.1 × 8.18 mm
- Φ273.0 × 9.27 mm
- Φ323.9 × 10.31 mm
- Φ406.4 × 12.70 mm
- Φ508 × 15.09 mm
- Φ610 × 17.45 mm
Important Note
Schedule (SCH) is not the only way to specify seamless steel pipe dimensions. Different standards may use different dimensional systems, such as ASTM/ASME, EN, DIN, and GB/T. Therefore, when requesting a quotation, it is best to specify the following details clearly:
Standard + Steel Grade + Outside Diameter + Wall Thickness + Length + Wall Thickness Tolerance
For example:
ASTM A106 Gr. B Seamless Steel Pipe, OD 168.3 mm × WT 7.11 mm × 6000 mm
This allows the manufacturer to provide an accurate quotation and ensure correct production.