ASME B36.10M (welded and seamless wrought steel pipe) · DN 100
Outside diameter 4.500" (114.30 mm), wall 0.438" (11.13 mm), inside diameter 3.624" (92.04 mm), 19.02 lb per foot.
| Trade size | NPS 4 · DN 100 |
|---|---|
| Schedule | Schedule 120 |
| Standard | ASME B36.10M (welded and seamless wrought steel pipe) |
| Outside diameter | 4.500" · 114.30 mm |
| Wall thickness | 0.438" · 11.13 mm |
| Inside diameter | 3.624" · 92.04 mm |
| Weight, plain end | 19.02 lb/ft · 28.32 kg/m |
Cross-check: the standard plain-end weight formula W = 10.6802 x t x (OD - t) gives 19.00 lb/ft here, 0.1% from the published 19.02 lb/ft. The published figure is the one printed above.
NPS 4 schedule 120 pipe measures 4.500 in (114.30 mm) across the outside with a 0.438 in wall, so the bore is 3.624 in (92.04 mm). That bore gives a flow area of 10.31 in² and holds 0.5358 US gallons per foot (6.655 litres per metre). The outside diameter is 10.3 times the wall, and the steel itself has a cross-section of 5.589 in² and weighs 19.02 lb per foot plain end. One trade size up, NPS 5 in the same schedule carries 1.59 times the flow area.
Schedule 80 is the next lighter wall at NPS 4: 0.337 in, 0.101 in thinner, which opens the bore to 3.826 in and adds 11% to the flow area, for 21% less weight per foot.
Schedule 160 is the next heavier wall at NPS 4: 0.531 in, 0.093 in thicker, which narrows the bore to 3.438 in and cuts 10% from the flow area, for 18% more weight per foot.
Next trade size up in this schedule: NPS 5 schedule 120, bore 4.563 in.
| Flow area | 10.31 in² |
|---|---|
| Capacity | 0.5358 US gal/ft · 6.655 L/m |
| Metal area | 5.589 in² |
| Moment of inertia | 11.66 in⁴ |
| Section modulus | 5.183 in³ |
| Radius of gyration | 1.444 in |
| Outside surface | 1.178 ft² per foot |
Plain geometry of a hollow circle with OD = 4.500 in and ID = 3.624 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 4 pipe has an outside diameter of 4.500 inches, and it keeps that outside diameter in every schedule made. What the schedule number changes is the wall: at schedule 120 the wall is 0.438 inches, so the bore comes out at 3.624 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 4.500 inches throughout - only the wall and the bore move.
| Schedule | Wall (in) | ID (in) | Weight (lb/ft) |
|---|---|---|---|
| Schedule 5 · 5S | 0.083 | 4.334 | 3.92 |
| Schedule 10 · 10S | 0.120 | 4.260 | 5.62 |
| Schedule 30 | 0.188 | 4.124 | 8.67 |
| Schedule 40 · STD, 40S | 0.237 | 4.026 | 10.80 |
| Schedule 80 · XS, 80S | 0.337 | 3.826 | 14.98 |
| Schedule 160 | 0.531 | 3.438 | 22.53 |
| Double extra strong (XXS) | 0.674 | 3.152 | 27.57 |
0.438 inches (11.13 mm). The outside diameter is 4.500 inches (114.30 mm) whatever the schedule, so this wall leaves an inside diameter of 3.624 inches.
3.624 inches (92.04 mm). Inside diameter is outside diameter minus twice the wall: 4.500 - 2 x 0.438 = 3.624 inches.
No. NPS 4 is a trade size, not a measurement. The pipe measures 4.500 inches across the outside and 3.624 inches across the bore in this schedule. Only the outside diameter is fixed across schedules.
19.02 pounds per foot plain end (28.32 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 - 0.438 in (b3610m-etb), 0.438 in (b3610m-fbc), 0.437 in (b3610m-wikipedia); 11.13 mm (b3610m-ferrobend), 11.13 mm (b3610m-wermac), 11.1 mm (b3610m-wikipedia). The figure printed is 0.438 in (11.13 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