ASME B36.10M (welded and seamless wrought steel pipe) · DN 100
Outside diameter 4.500" (114.30 mm), wall 0.531" (13.49 mm), inside diameter 3.438" (87.32 mm), 22.53 lb per foot.
| Trade size | NPS 4 · DN 100 |
|---|---|
| Schedule | Schedule 160 |
| Standard | ASME B36.10M (welded and seamless wrought steel pipe) |
| Outside diameter | 4.500" · 114.30 mm |
| Wall thickness | 0.531" · 13.49 mm |
| Inside diameter | 3.438" · 87.32 mm |
| Weight, plain end | 22.53 lb/ft · 33.54 kg/m |
Cross-check: the standard plain-end weight formula W = 10.6802 x t x (OD - t) gives 22.51 lb/ft here, 0.1% from the published 22.53 lb/ft. The published figure is the one printed above.
NPS 4 schedule 160 pipe measures 4.500 in (114.30 mm) across the outside with a 0.531 in wall, so the bore is 3.438 in (87.32 mm). That bore gives a flow area of 9.283 in² and holds 0.4822 US gallons per foot (5.989 litres per metre). The outside diameter is 8.5 times the wall, and the steel itself has a cross-section of 6.621 in² and weighs 22.53 lb per foot plain end. One trade size up, NPS 5 in the same schedule carries 1.57 times the flow area.
Schedule 120 is the next lighter wall at NPS 4: 0.438 in, 0.093 in thinner, which opens the bore to 3.624 in and adds 11% to the flow area, for 16% less weight per foot.
Double extra strong (XXS) is the next heavier wall at NPS 4: 0.674 in, 0.143 in thicker, which narrows the bore to 3.152 in and cuts 16% from the flow area, for 22% more weight per foot.
Next trade size up in this schedule: NPS 5 schedule 160, bore 4.313 in.
| Flow area | 9.283 in² |
|---|---|
| Capacity | 0.4822 US gal/ft · 5.989 L/m |
| Metal area | 6.621 in² |
| Moment of inertia | 13.27 in⁴ |
| Section modulus | 5.898 in³ |
| Radius of gyration | 1.416 in |
| Outside surface | 1.178 ft² per foot |
Plain geometry of a hollow circle with OD = 4.500 in and ID = 3.438 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 160 the wall is 0.531 inches, so the bore comes out at 3.438 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 120 | 0.438 | 3.624 | 19.02 |
| Double extra strong (XXS) | 0.674 | 3.152 | 27.57 |
0.531 inches (13.49 mm). The outside diameter is 4.500 inches (114.30 mm) whatever the schedule, so this wall leaves an inside diameter of 3.438 inches.
3.438 inches (87.32 mm). Inside diameter is outside diameter minus twice the wall: 4.500 - 2 x 0.531 = 3.438 inches.
No. NPS 4 is a trade size, not a measurement. The pipe measures 4.500 inches across the outside and 3.438 inches across the bore in this schedule. Only the outside diameter is fixed across schedules.
22.53 pounds per foot plain end (33.54 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:
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