ASME B36.10 · Pipe schedule
Outside diameter, wall thickness, inside diameter, and weight per foot for Schedule 40 and Schedule 80 carbon-steel pipe, NPS 1/2" through 12".
| NPS | OD (in) | Sch 40 wall | Sch 40 ID | Sch 40 lb/ft | Sch 80 wall | Sch 80 ID | Sch 80 lb/ft |
|---|---|---|---|---|---|---|---|
| 1/2" | 0.84 | 0.109 | 0.622 | 0.85 | 0.147 | 0.546 | 1.09 |
| 3/4" | 1.05 | 0.113 | 0.824 | 1.13 | 0.154 | 0.742 | 1.47 |
| 1" | 1.315 | 0.133 | 1.049 | 1.68 | 0.179 | 0.957 | 2.17 |
| 1-1/4" | 1.66 | 0.14 | 1.38 | 2.27 | 0.191 | 1.278 | 3 |
| 1-1/2" | 1.9 | 0.145 | 1.61 | 2.72 | 0.2 | 1.5 | 3.63 |
| 2" | 2.375 | 0.154 | 2.067 | 3.65 | 0.218 | 1.939 | 5.02 |
| 2-1/2" | 2.875 | 0.203 | 2.469 | 5.79 | 0.276 | 2.323 | 7.66 |
| 3" | 3.5 | 0.216 | 3.068 | 7.58 | 0.3 | 2.9 | 10.25 |
| 4" | 4.5 | 0.237 | 4.026 | 10.79 | 0.337 | 3.826 | 14.98 |
| 6" | 6.625 | 0.28 | 6.065 | 18.97 | 0.432 | 5.761 | 28.57 |
| 8" | 8.625 | 0.322 | 7.981 | 28.55 | 0.5 | 7.625 | 43.39 |
| 10" | 10.75 | 0.365 | 10.02 | 40.48 | 0.5 | 9.75 | 54.74 |
| 12" | 12.75 | 0.375 | 12 | 49.56 | 0.5 | 11.75 | 65.42 |
Carbon-steel pipe dimensions per ASME B36.10M (NPS = nominal pipe size; OD is fixed for a given NPS while wall thickness sets the schedule). Weights are for plain-end pipe and are nominal. Sch 40 = STD and Sch 80 = XS through 10"; they diverge at larger sizes.
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Steel pipe is sized by nominal pipe size (NPS) and a schedule that sets the wall thickness. For a given NPS the outside diameter is fixed — only the wall (and therefore the inside diameter, weight, and pressure rating) changes with the schedule. That's why a 2" Sch 80 pipe threads the same fittings as 2" Sch 40 but has a smaller bore.
Schedule 40 covers most plumbing and low-pressure piping; Schedule 80 adds wall for higher pressure and mechanical strength. Through NPS 10, Sch 40 equals STD and Sch 80 equals XS — above that they diverge.
For weld-process piping, traceability matters as much as dimensions. Field PM's weld mapping tracks every joint, welder, and NDE result against the spool drawings; the copper tube chart covers tube sizes for plumbing and refrigerant lines.
For a given nominal pipe size the outside diameter is identical; Schedule 80 has a thicker wall, so it has a smaller inside diameter, higher pressure rating, and more weight per foot. Schedule 40 is standard for most plumbing and low-pressure work; Schedule 80 is used for higher pressure and mechanical strength.
No. Nominal pipe size (NPS) is a label, not a measurement. A "2-inch" pipe has a 2.375" outside diameter; the inside diameter varies with the schedule (2.067" for Sch 40, 1.939" for Sch 80).
Through NPS 10, Schedule 40 matches STD (standard) wall and Schedule 80 matches XS (extra-strong). Above NPS 10 the schedules and STD/XS walls diverge, so confirm against the dimension table for large pipe.
Use the lb/ft columns here (plain-end, nominal) and multiply by total length for a takeoff. For exact weights including coatings or threading, use the mill's certified data.
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