ASME B36.10M (welded and seamless wrought steel pipe) · DN 125
Outside diameter 5.563" (141.30 mm), wall 0.625" (15.88 mm), inside diameter 4.313" (109.54 mm), 32.99 lb per foot.
| Trade size | NPS 5 · DN 125 |
|---|---|
| Schedule | Schedule 160 |
| Standard | ASME B36.10M (welded and seamless wrought steel pipe) |
| Outside diameter | 5.563" · 141.30 mm |
| Wall thickness | 0.625" · 15.88 mm |
| Inside diameter | 4.313" · 109.54 mm |
| Weight, plain end | 32.99 lb/ft · 49.12 kg/m |
Cross-check: the standard plain-end weight formula W = 10.6802 x t x (OD - t) gives 32.96 lb/ft here, 0.1% from the published 32.99 lb/ft. The published figure is the one printed above.
NPS 5 schedule 160 pipe measures 5.563 in (141.30 mm) across the outside with a 0.625 in wall, so the bore is 4.313 in (109.54 mm). That bore gives a flow area of 14.61 in² and holds 0.7590 US gallons per foot (9.426 litres per metre). The outside diameter is 8.9 times the wall, and the steel itself has a cross-section of 9.696 in² and weighs 32.99 lb per foot plain end. One trade size up, NPS 6 in the same schedule carries 1.45 times the flow area.
Schedule 120 is the next lighter wall at NPS 5: 0.500 in, 0.125 in thinner, which opens the bore to 4.563 in and adds 12% to the flow area, for 18% less weight per foot.
Double extra strong (XXS) is the next heavier wall at NPS 5: 0.750 in, 0.125 in thicker, which narrows the bore to 4.063 in and cuts 11% from the flow area, for 17% more weight per foot.
Next trade size up in this schedule: NPS 6 schedule 160, bore 5.187 in.
| Flow area | 14.61 in² |
|---|---|
| Capacity | 0.7590 US gal/ft · 9.426 L/m |
| Metal area | 9.696 in² |
| Moment of inertia | 30.03 in⁴ |
| Section modulus | 10.79 in³ |
| Radius of gyration | 1.760 in |
| Outside surface | 1.456 ft² per foot |
Plain geometry of a hollow circle with OD = 5.563 in and ID = 4.313 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 5 pipe has an outside diameter of 5.563 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 0.625 inches, so the bore comes out at 4.313 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 5.563 inches throughout - only the wall and the bore move.
| Schedule | Wall (in) | ID (in) | Weight (lb/ft) |
|---|---|---|---|
| Schedule 5 · 5S | 0.109 | 5.345 | 6.36 |
| Schedule 10 · 10S | 0.134 | 5.295 | 7.78 |
| Schedule 40 · STD, 40S | 0.258 | 5.047 | 14.63 |
| Schedule 80 · XS, 80S | 0.375 | 4.813 | 20.80 |
| Schedule 120 | 0.500 | 4.563 | 27.06 |
| Double extra strong (XXS) | 0.750 | 4.063 | 38.59 |
0.625 inches (15.88 mm). The outside diameter is 5.563 inches (141.30 mm) whatever the schedule, so this wall leaves an inside diameter of 4.313 inches.
4.313 inches (109.54 mm). Inside diameter is outside diameter minus twice the wall: 5.563 - 2 x 0.625 = 4.313 inches.
No. NPS 5 is a trade size, not a measurement. The pipe measures 5.563 inches across the outside and 4.313 inches across the bore in this schedule. Only the outside diameter is fixed across schedules.
32.99 pounds per foot plain end (49.12 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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