ASME B36.10M (welded and seamless wrought steel pipe) · DN 65
Outside diameter 2.875" (73.02 mm), wall 0.375" (9.53 mm), inside diameter 2.125" (53.96 mm), 10.02 lb per foot.
| Trade size | NPS 2-1/2 · DN 65 |
|---|---|
| Schedule | Schedule 160 |
| Standard | ASME B36.10M (welded and seamless wrought steel pipe) |
| Outside diameter | 2.875" · 73.02 mm · designated 73 mm in the metric column |
| Wall thickness | 0.375" · 9.53 mm |
| Inside diameter | 2.125" · 53.96 mm |
| Weight, plain end | 10.02 lb/ft · 14.92 kg/m |
Cross-check: the standard plain-end weight formula W = 10.6802 x t x (OD - t) gives 10.01 lb/ft here, 0.1% from the published 10.02 lb/ft. The published figure is the one printed above.
NPS 2-1/2 schedule 160 pipe measures 2.875 in (73.02 mm) across the outside with a 0.375 in wall, so the bore is 2.125 in (53.96 mm). That bore gives a flow area of 3.547 in² and holds 0.1842 US gallons per foot (2.288 litres per metre). The outside diameter is 7.7 times the wall, and the steel itself has a cross-section of 2.945 in² and weighs 10.02 lb per foot plain end. One trade size up, NPS 3 in the same schedule carries 1.52 times the flow area.
Schedule 80 is the next lighter wall at NPS 2-1/2: 0.276 in, 0.099 in thinner, which opens the bore to 2.323 in and adds 20% to the flow area, for 23% less weight per foot.
Double extra strong (XXS) is the next heavier wall at NPS 2-1/2: 0.552 in, 0.177 in thicker, which narrows the bore to 1.771 in and cuts 31% from the flow area, for 37% more weight per foot.
Next trade size up in this schedule: NPS 3 schedule 160, bore 2.624 in.
| Flow area | 3.547 in² |
|---|---|
| Capacity | 0.1842 US gal/ft · 2.288 L/m |
| Metal area | 2.945 in² |
| Moment of inertia | 2.353 in⁴ |
| Section modulus | 1.637 in³ |
| Radius of gyration | 0.8938 in |
| Outside surface | 0.7527 ft² per foot |
Plain geometry of a hollow circle with OD = 2.875 in and ID = 2.125 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 2-1/2 pipe has an outside diameter of 2.875 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 0.375 inches, so the bore comes out at 2.125 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 2.875 inches throughout - only the wall and the bore move.
| Schedule | Wall (in) | ID (in) | Weight (lb/ft) |
|---|---|---|---|
| Schedule 5 · 5S | 0.083 | 2.709 | 2.48 |
| Schedule 10 · 10S | 0.120 | 2.635 | 3.53 |
| Schedule 30 | 0.188 | 2.499 | 5.40 |
| Schedule 40 · STD, 40S | 0.203 | 2.469 | 5.80 |
| Schedule 80 · XS, 80S | 0.276 | 2.323 | 7.67 |
| Double extra strong (XXS) | 0.552 | 1.771 | 13.71 |
0.375 inches (9.53 mm). The outside diameter is 2.875 inches (73.02 mm) whatever the schedule, so this wall leaves an inside diameter of 2.125 inches.
2.125 inches (53.96 mm). Inside diameter is outside diameter minus twice the wall: 2.875 - 2 x 0.375 = 2.125 inches.
No. NPS 2-1/2 is a trade size, not a measurement. The pipe measures 2.875 inches across the outside and 2.125 inches across the bore in this schedule. Only the outside diameter is fixed across schedules.
10.02 pounds per foot plain end (14.92 kg per metre), for carbon steel. The figure excludes coatings, linings and fittings.
One schedule at NPS 2-1/2 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