ASME B36.10M (welded and seamless wrought steel pipe) · DN 80
Outside diameter 3.500" (88.90 mm), wall 0.188" (4.78 mm), inside diameter 3.124" (79.34 mm), 6.66 lb per foot.
| Trade size | NPS 3 · DN 80 |
|---|---|
| Schedule | Schedule 30 |
| Standard | ASME B36.10M (welded and seamless wrought steel pipe) |
| Outside diameter | 3.500" · 88.90 mm |
| Wall thickness | 0.188" · 4.78 mm |
| Inside diameter | 3.124" · 79.34 mm |
| Weight, plain end | 6.66 lb/ft · 9.92 kg/m |
Cross-check: the standard plain-end weight formula W = 10.6802 x t x (OD - t) gives 6.65 lb/ft here, 0.1% from the published 6.66 lb/ft. The published figure is the one printed above.
NPS 3 schedule 30 pipe measures 3.500 in (88.90 mm) across the outside with a 0.188 in wall, so the bore is 3.124 in (79.34 mm). That bore gives a flow area of 7.665 in² and holds 0.3982 US gallons per foot (4.945 litres per metre). The outside diameter is 18.6 times the wall, and the steel itself has a cross-section of 1.956 in² and weighs 6.66 lb per foot plain end. One trade size up, NPS 3-1/2 in the same schedule carries 1.35 times the flow area.
Schedule 10 is the next lighter wall at NPS 3: 0.120 in, 0.068 in thinner, which opens the bore to 3.260 in and adds 8.9% to the flow area, for 35% less weight per foot.
Schedule 40 is the next heavier wall at NPS 3: 0.216 in, 0.028 in thicker, which narrows the bore to 3.068 in and cuts 3.6% from the flow area, for 14% more weight per foot.
Next trade size up in this schedule: NPS 3-1/2 schedule 30, bore 3.624 in.
| Flow area | 7.665 in² |
|---|---|
| Capacity | 0.3982 US gal/ft · 4.945 L/m |
| Metal area | 1.956 in² |
| Moment of inertia | 2.691 in⁴ |
| Section modulus | 1.538 in³ |
| Radius of gyration | 1.173 in |
| Outside surface | 0.9163 ft² per foot |
Plain geometry of a hollow circle with OD = 3.500 in and ID = 3.124 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 schedule 30 the wall is 0.188 inches, so the bore comes out at 3.124 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 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 |
| Double extra strong (XXS) | 0.600 | 2.300 | 18.60 |
0.188 inches (4.78 mm). The outside diameter is 3.500 inches (88.90 mm) whatever the schedule, so this wall leaves an inside diameter of 3.124 inches.
3.124 inches (79.34 mm). Inside diameter is outside diameter minus twice the wall: 3.500 - 2 x 0.188 = 3.124 inches.
No. NPS 3 is a trade size, not a measurement. The pipe measures 3.500 inches across the outside and 3.124 inches across the bore in this schedule. Only the outside diameter is fixed across schedules.
6.66 pounds per foot plain end (9.92 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 4 independent published sources:
Nearby sizes