ASME B36.10M (welded and seamless wrought steel pipe) · DN 80
Outside diameter 3.500" (88.90 mm), wall 0.600" (15.24 mm), inside diameter 2.300" (58.42 mm), 18.60 lb per foot.
| Trade size | NPS 3 · DN 80 |
|---|---|
| Schedule | Double extra strong (XXS) |
| Standard | ASME B36.10M (welded and seamless wrought steel pipe) |
| Outside diameter | 3.500" · 88.90 mm |
| Wall thickness | 0.600" · 15.24 mm |
| Inside diameter | 2.300" · 58.42 mm |
| Weight, plain end | 18.60 lb/ft · 27.68 kg/m |
Cross-check: the standard plain-end weight formula W = 10.6802 x t x (OD - t) gives 18.58 lb/ft here, 0.1% from the published 18.60 lb/ft. The published figure is the one printed above.
NPS 3 double extra strong (xxs) pipe measures 3.500 in (88.90 mm) across the outside with a 0.600 in wall, so the bore is 2.300 in (58.42 mm). That bore gives a flow area of 4.155 in² and holds 0.2158 US gallons per foot (2.680 litres per metre). The outside diameter is 5.8 times the wall, and the steel itself has a cross-section of 5.466 in² and weighs 18.60 lb per foot plain end.
Schedule 160 is the next lighter wall at NPS 3: 0.438 in, 0.162 in thinner, which opens the bore to 2.624 in and adds 30% to the flow area, for 23% less weight per foot.
| Flow area | 4.155 in² |
|---|---|
| Capacity | 0.2158 US gal/ft · 2.680 L/m |
| Metal area | 5.466 in² |
| Moment of inertia | 5.993 in⁴ |
| Section modulus | 3.424 in³ |
| Radius of gyration | 1.047 in |
| Outside surface | 0.9163 ft² per foot |
Plain geometry of a hollow circle with OD = 3.500 in and ID = 2.300 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 3 pipe has an outside diameter of 3.500 inches, and it keeps that outside diameter in every schedule made. What the schedule number changes is the wall: at double extra strong (xxs) the wall is 0.600 inches, so the bore comes out at 2.300 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 3.500 inches throughout - only the wall and the bore move.
| Schedule | Wall (in) | ID (in) | Weight (lb/ft) |
|---|---|---|---|
| Schedule 5 · 5S | 0.083 | 3.334 | 3.03 |
| Schedule 10 · 10S | 0.120 | 3.260 | 4.34 |
| Schedule 30 | 0.188 | 3.124 | 6.66 |
| Schedule 40 · STD, 40S | 0.216 | 3.068 | 7.58 |
| Schedule 80 · XS, 80S | 0.300 | 2.900 | 10.26 |
| Schedule 160 | 0.438 | 2.624 | 14.34 |
0.600 inches (15.24 mm). The outside diameter is 3.500 inches (88.90 mm) whatever the schedule, so this wall leaves an inside diameter of 2.300 inches.
2.300 inches (58.42 mm). Inside diameter is outside diameter minus twice the wall: 3.500 - 2 x 0.600 = 2.300 inches.
No. NPS 3 is a trade size, not a measurement. The pipe measures 3.500 inches across the outside and 2.300 inches across the bore in this schedule. Only the outside diameter is fixed across schedules.
18.60 pounds per foot plain end (27.68 kg per metre), for carbon steel. The figure excludes coatings, linings and fittings.
One schedule at NPS 3 appears in only one of the published tables cross-checked for this section, so it is named rather than printed: 120. Everything shown above carries at least two independent sources.
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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