ASME B36.10M (welded and seamless wrought steel pipe) · DN 250
Outside diameter 10.750" (273.05 mm), wall 0.250" (6.35 mm), inside diameter 10.250" (260.35 mm), 28.06 lb per foot.
| Trade size | NPS 10 · DN 250 |
|---|---|
| Schedule | Schedule 20 |
| Standard | ASME B36.10M (welded and seamless wrought steel pipe) |
| Outside diameter | 10.750" · 273.05 mm · designated 273 mm in the metric column |
| Wall thickness | 0.250" · 6.35 mm |
| Inside diameter | 10.250" · 260.35 mm |
| Weight, plain end | 28.06 lb/ft · 41.76 kg/m |
Cross-check: the standard plain-end weight formula W = 10.6802 x t x (OD - t) gives 28.04 lb/ft here, 0.1% from the published 28.06 lb/ft. The published figure is the one printed above.
NPS 10 schedule 20 pipe measures 10.750 in (273.05 mm) across the outside with a 0.250 in wall, so the bore is 10.250 in (260.35 mm). That bore gives a flow area of 82.52 in² and holds 4.287 US gallons per foot (53.24 litres per metre). The outside diameter is 43.0 times the wall, and the steel itself has a cross-section of 8.247 in² and weighs 28.06 lb per foot plain end. One trade size up, NPS 12 in the same schedule carries 1.43 times the flow area.
Schedule 10 is the next lighter wall at NPS 10: 0.165 in, 0.085 in thinner, which opens the bore to 10.420 in and adds 3.3% to the flow area, for 33% less weight per foot.
Schedule 30 is the next heavier wall at NPS 10: 0.307 in, 0.057 in thicker, which narrows the bore to 10.136 in and cuts 2.2% from the flow area, for 22% more weight per foot.
Next trade size up in this schedule: NPS 12 schedule 20, bore 12.250 in.
| Flow area | 82.52 in² |
|---|---|
| Capacity | 4.287 US gal/ft · 53.24 L/m |
| Metal area | 8.247 in² |
| Moment of inertia | 113.7 in⁴ |
| Section modulus | 21.16 in³ |
| Radius of gyration | 3.713 in |
| Outside surface | 2.814 ft² per foot |
Plain geometry of a hollow circle with OD = 10.750 in and ID = 10.250 in: flow area π/4·ID², metal area π/4·(OD² − ID²), moment of inertia π/64·(OD⁴ − ID⁴), section modulus I ÷ (OD/2), radius of gyration √(I ÷ metal area), capacity flow area × 12 ÷ 231 (231 in³ to the US gallon). Nominal dimensions, so mill tolerance and corrosion allowance are not included.
Nominal Pipe Size is a label, not a measurement. NPS 10 pipe has an outside diameter of 10.750 inches, and it keeps that outside diameter in every schedule made. What the schedule number changes is the wall: at schedule 20 the wall is 0.250 inches, so the bore comes out at 10.250 inches.
That is the practical consequence. Fittings, flanges, supports and threading dies are sized to the outside diameter, so they fit any schedule of the same trade size. Flow, pressure drop and anything that has to pass through the pipe depend on the inside diameter, which changes with every schedule. Order by trade size and schedule; work your hydraulics from the bore.
Same outside diameter of 10.750 inches throughout - only the wall and the bore move.
| Schedule | Wall (in) | ID (in) | Weight (lb/ft) |
|---|---|---|---|
| Schedule 5 · 5S | 0.134 | 10.482 | 15.21 |
| Schedule 10 · 10S | 0.165 | 10.420 | 18.67 |
| Schedule 30 | 0.307 | 10.136 | 34.27 |
| Schedule 40 · STD, 40S | 0.365 | 10.020 | 40.52 |
| Schedule 80 | 0.594 | 9.562 | 64.49 |
| Schedule 100 | 0.719 | 9.312 | 77.10 |
| Schedule 120 | 0.844 | 9.062 | 89.38 |
| Schedule 160 | 1.125 | 8.500 | 115.75 |
| Extra strong (XS) · 60, 80S | 0.500 | 9.750 | 54.79 |
| Double extra strong (XXS) · 140 | 1.000 | 8.750 | 104.23 |
0.250 inches (6.35 mm). The outside diameter is 10.750 inches (273.05 mm) whatever the schedule, so this wall leaves an inside diameter of 10.250 inches.
10.250 inches (260.35 mm). Inside diameter is outside diameter minus twice the wall: 10.750 - 2 x 0.250 = 10.250 inches.
No. NPS 10 is a trade size, not a measurement. The pipe measures 10.750 inches across the outside and 10.250 inches across the bore in this schedule. Only the outside diameter is fixed across schedules.
28.06 pounds per foot plain end (41.76 kg per metre), for carbon steel. The figure excludes coatings, linings and fittings.
This table runs from NPS 1/8 to NPS 24 and stops there. ASME B36.10M itself continues to NPS 80; those larger sizes are not carried here, so a size above NPS 24 is missing rather than undefined.
Dimensions are as defined by ASME B36.10M (welded and seamless wrought steel pipe). This site is an independent reference and is not affiliated with, endorsed by or approved by any standards body.
Every value on this page was cross-checked against 5 independent published sources:
Nearby sizes