ASME B36.10M (welded and seamless wrought steel pipe) · DN 80
Outside diameter 3.500" (88.90 mm), wall 0.083" (2.11 mm), inside diameter 3.334" (84.68 mm), 3.03 lb per foot.
| Trade size | NPS 3 · DN 80 |
|---|---|
| Schedule | Schedule 5 · same wall as 5S |
| Standard | ASME B36.10M (welded and seamless wrought steel pipe) |
| Outside diameter | 3.500" · 88.90 mm |
| Wall thickness | 0.083" · 2.11 mm |
| Inside diameter | 3.334" · 84.68 mm |
| Weight, plain end | 3.03 lb/ft · 4.52 kg/m |
Cross-check: the standard plain-end weight formula W = 10.6802 x t x (OD - t) gives 3.03 lb/ft here, 0.0% from the published 3.03 lb/ft. The published figure is the one printed above.
NPS 3 schedule 5 pipe measures 3.500 in (88.90 mm) across the outside with a 0.083 in wall, so the bore is 3.334 in (84.68 mm). That bore gives a flow area of 8.730 in² and holds 0.4535 US gallons per foot (5.632 litres per metre). The outside diameter is 42.2 times the wall, and the steel itself has a cross-section of 0.8910 in² and weighs 3.03 lb per foot plain end. One trade size up, NPS 3-1/2 in the same schedule carries 1.32 times the flow area.
Schedule 10 is the next heavier wall at NPS 3: 0.120 in, 0.037 in thicker, which narrows the bore to 3.260 in and cuts 4.4% from the flow area, for 43% more weight per foot.
Next trade size up in this schedule: NPS 3-1/2 schedule 5, bore 3.834 in.
| Flow area | 8.730 in² |
|---|---|
| Capacity | 0.4535 US gal/ft · 5.632 L/m |
| Metal area | 0.8910 in² |
| Moment of inertia | 1.301 in⁴ |
| Section modulus | 0.7435 in³ |
| Radius of gyration | 1.208 in |
| Outside surface | 0.9163 ft² per foot |
Plain geometry of a hollow circle with OD = 3.500 in and ID = 3.334 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 5 the wall is 0.083 inches, so the bore comes out at 3.334 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 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 |
| Double extra strong (XXS) | 0.600 | 2.300 | 18.60 |
0.083 inches (2.11 mm). The outside diameter is 3.500 inches (88.90 mm) whatever the schedule, so this wall leaves an inside diameter of 3.334 inches.
3.334 inches (84.68 mm). Inside diameter is outside diameter minus twice the wall: 3.500 - 2 x 0.083 = 3.334 inches.
No. NPS 3 is a trade size, not a measurement. The pipe measures 3.500 inches across the outside and 3.334 inches across the bore in this schedule. Only the outside diameter is fixed across schedules.
3.03 pounds per foot plain end (4.52 kg per metre), for carbon steel. The figure excludes coatings, linings and fittings.
Yes, at NPS 3. 5S is the same 0.083 inch wall here. That coincidence is per size and does not hold everywhere: standard wall and schedule 40 part company above NPS 10, and extra strong and schedule 80 part company above NPS 8.
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:
Nearby sizes