ASME B36.10M (welded and seamless wrought steel pipe) · DN 15
Outside diameter 0.840" (21.34 mm), wall 0.188" (4.78 mm), inside diameter 0.464" (11.78 mm), 1.31 lb per foot.
| Trade size | NPS 1/2 · DN 15 |
|---|---|
| Schedule | Schedule 160 |
| Standard | ASME B36.10M (welded and seamless wrought steel pipe) |
| Outside diameter | 0.840" · 21.34 mm · designated 21.3 mm in the metric column |
| Wall thickness | 0.188" · 4.78 mm |
| Inside diameter | 0.464" · 11.78 mm |
| Weight, plain end | 1.31 lb/ft · 1.95 kg/m |
Cross-check: the standard plain-end weight formula W = 10.6802 x t x (OD - t) gives 1.31 lb/ft here, 0.1% from the published 1.31 lb/ft. The published figure is the one printed above.
NPS 1/2 schedule 160 pipe measures 0.840 in (21.34 mm) across the outside with a 0.188 in wall, so the bore is 0.464 in (11.78 mm). That bore gives a flow area of 0.1691 in² and holds 0.008784 US gallons per foot (0.1091 litres per metre). The outside diameter is 4.5 times the wall, and the steel itself has a cross-section of 0.3851 in² and weighs 1.31 lb per foot plain end. One trade size up, NPS 3/4 in the same schedule carries 1.74 times the flow area.
Schedule 80 is the next lighter wall at NPS 1/2: 0.147 in, 0.041 in thinner, which opens the bore to 0.546 in and adds 38% to the flow area, for 17% less weight per foot.
Double extra strong (XXS) is the next heavier wall at NPS 1/2: 0.294 in, 0.106 in thicker, which narrows the bore to 0.252 in and cuts 71% from the flow area, for 31% more weight per foot.
Next trade size up in this schedule: NPS 3/4 schedule 160, bore 0.612 in.
| Flow area | 0.1691 in² |
|---|---|
| Capacity | 0.008784 US gal/ft · 0.1091 L/m |
| Metal area | 0.3851 in² |
| Moment of inertia | 0.02216 in⁴ |
| Section modulus | 0.05277 in³ |
| Radius of gyration | 0.2399 in |
| Outside surface | 0.2199 ft² per foot |
Plain geometry of a hollow circle with OD = 0.840 in and ID = 0.464 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 1/2 pipe has an outside diameter of 0.840 inches, and it keeps that outside diameter in every schedule made. What the schedule number changes is the wall: at schedule 160 the wall is 0.188 inches, so the bore comes out at 0.464 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 0.840 inches throughout - only the wall and the bore move.
| Schedule | Wall (in) | ID (in) | Weight (lb/ft) |
|---|---|---|---|
| Schedule 5 · 5S | 0.065 | 0.710 | 0.54 |
| Schedule 10 · 10S | 0.083 | 0.674 | 0.67 |
| Schedule 30 | 0.095 | 0.650 | 0.76 |
| Schedule 40 · STD, 40S | 0.109 | 0.622 | 0.85 |
| Schedule 80 · XS, 80S | 0.147 | 0.546 | 1.09 |
| Double extra strong (XXS) | 0.294 | 0.252 | 1.71 |
0.188 inches (4.78 mm). The outside diameter is 0.840 inches (21.34 mm) whatever the schedule, so this wall leaves an inside diameter of 0.464 inches.
0.464 inches (11.78 mm). Inside diameter is outside diameter minus twice the wall: 0.840 - 2 x 0.188 = 0.464 inches.
No. NPS 1/2 is a trade size, not a measurement. The pipe measures 0.840 inches across the outside and 0.464 inches across the bore in this schedule. Only the outside diameter is fixed across schedules.
1.31 pounds per foot plain end (1.95 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:
Sources disagree here. Published tables split on the last digit here - 0.187 in (b3610m-etb), 0.188 in (b3610m-fbc), 0.188 in (b3610m-wikipedia). The figure printed is 0.188 in (4.78 mm), carried by the majority of the sources. The two readings describe the same wall: they differ by less than a thousandth of an inch, far inside the mill tolerance of minus 12.5 percent on wall thickness.
Last-digit inch walls across the whole table: 0.594, 0.688, 0.719, 0.844, 0.938, 1.094, 1.219, 1.438, 1.969, 2.344 in (b3610m-fbc) against 0.593, 0.687, 0.718, 0.843, 0.937, 1.093, 1.218, 1.437, 1.968, 2.343 in (b3610m-wikipedia). Two families of inch figures are in circulation, one a thousandth of an inch below the other, and they come from rounding the millimetre wall the standard tabulates rather than from any difference in the pipe. The higher family is what the majority of the sources read here carry and is what this site prints; the affected rows say so individually. Nothing turns on the choice: the wall tolerance is minus 12.5 percent, which at a half-inch wall is sixty times the gap.
NPS 14 extra strong (XS): 0.469 in (b3610m-fbc) against 0.500 in (b3610m-etb) against 0.500 in (b3610m-wikipedia). 0.500 in is printed here. Two of the three inch sources give it, both millimetre sources give 12.70 mm which is 0.500 in, and extra strong is a 0.500 in wall at every size from NPS 12 up. The 0.469 in reading looks like a misplaced row in that one chart, but it is recorded rather than deleted.
Nearby sizes