Schedule 40 (SCH 40) is the most commonly used wall thickness designation for carbon steel pipe in industrial, commercial, and residential applications. It provides a balance of pressure rating and material cost, making it the default choice for general piping systems worldwide.
Schedule 40 pipe is sometimes called "standard weight" (STD) for sizes up to NPS 10". For NPS 12" and larger, STD wall thickness matches Schedule 30, not Schedule 40.
Formula (metric):
Weight (kg/m) = (OD − WT) × WT × 0.02466
Where: OD = outside diameter (mm), WT = wall thickness (mm), 0.02466 = carbon steel density factor
Example: 4" SCH 40 pipe — OD 114.3 mm, WT 6.02 mm
Weight = (114.3 − 6.02) × 6.02 × 0.02466 = 16.07 kg/m
Formula (imperial):
Weight (lb/ft) = (OD − WT) × WT × 10.69
Where: OD = outside diameter (inches), WT = wall thickness (inches)
| NPS | DN | OD (in) | OD (mm) | Wall (in) | Wall (mm) | Weight (lb/ft) | Weight (kg/m) | ID (in) |
|---|---|---|---|---|---|---|---|---|
| 1/8 | 6 | 0.405 | 10.29 | 0.068 | 1.73 | 0.24 | 0.36 | 0.269 |
| 1/4 | 8 | 0.540 | 13.72 | 0.088 | 2.24 | 0.42 | 0.63 | 0.364 |
| 3/8 | 10 | 0.675 | 17.15 | 0.091 | 2.31 | 0.57 | 0.85 | 0.493 |
| 1/2 | 15 | 0.840 | 21.34 | 0.109 | 2.77 | 0.85 | 1.27 | 0.622 |
| 3/4 | 20 | 1.050 | 26.67 | 0.113 | 2.87 | 1.13 | 1.69 | 0.824 |
| 1 | 25 | 1.315 | 33.40 | 0.133 | 3.38 | 1.68 | 2.50 | 1.049 |
| 1¼ | 32 | 1.660 | 42.16 | 0.140 | 3.56 | 2.27 | 3.39 | 1.380 |
| 1½ | 40 | 1.900 | 48.26 | 0.145 | 3.68 | 2.72 | 4.05 | 1.610 |
| 2 | 50 | 2.375 | 60.33 | 0.154 | 3.91 | 3.65 | 5.44 | 2.067 |
| 2½ | 65 | 2.875 | 73.03 | 0.203 | 5.16 | 5.79 | 8.63 | 2.469 |
| 3 | 80 | 3.500 | 88.90 | 0.216 | 5.49 | 7.58 | 11.29 | 3.068 |
| 3½ | 90 | 4.000 | 101.60 | 0.226 | 5.74 | 9.11 | 13.57 | 3.548 |
| 4 | 100 | 4.500 | 114.30 | 0.237 | 6.02 | 10.79 | 16.07 | 4.026 |
| 5 | 125 | 5.563 | 141.30 | 0.258 | 6.55 | 14.62 | 21.77 | 5.047 |
| 6 | 150 | 6.625 | 168.28 | 0.280 | 7.11 | 18.97 | 28.26 | 6.065 |
| 8 | 200 | 8.625 | 219.08 | 0.322 | 8.18 | 28.55 | 42.55 | 7.981 |
| 10 | 250 | 10.750 | 273.05 | 0.365 | 9.27 | 40.48 | 60.31 | 10.020 |
| 12 | 300 | 12.750 | 323.85 | 0.406 | 10.31 | 53.53 | 79.73 | 11.938 |
| 14 | 350 | 14.000 | 355.60 | 0.438 | 11.13 | 63.44 | 94.55 | 13.124 |
| 16 | 400 | 16.000 | 406.40 | 0.500 | 12.70 | 82.77 | 123.30 | 15.000 |
| 18 | 450 | 18.000 | 457.20 | 0.562 | 14.27 | 104.66 | 155.80 | 16.876 |
| 20 | 500 | 20.000 | 508.00 | 0.594 | 15.09 | 123.10 | 183.42 | 18.812 |
| 24 | 600 | 24.000 | 609.60 | 0.688 | 17.48 | 171.24 | 255.41 | 22.624 |
Using Barlow's formula (simplified): P = (2 × S × t) / D
Where: S = allowable stress (20,000 psi for A53 Grade B at 72°F), t = wall thickness, D = outside diameter
| NPS | Max Working Pressure (psi) | Max Working Pressure (bar) |
|---|---|---|
| 1" | 4,046 | 279 |
| 2" | 2,592 | 179 |
| 4" | 2,107 | 145 |
| 6" | 1,690 | 117 |
| 8" | 1,493 | 103 |
| 10" | 1,358 | 94 |
| 12" | 1,274 | 88 |
Note: Actual working pressure depends on temperature, joint type, and application code. Always consult ASME B31.1/B31.3 for design calculations.
Sino East Steel stocks ASTM A53 Grade B and ASTM A106 Grade B Schedule 40 seamless pipe for immediate delivery. All pipes come with full MTC and inspection reports.