ASME B36.10M (welded and seamless wrought steel pipe) · DN 125
Outside diameter 5.563" (141.30 mm), wall 0.500" (12.70 mm), inside diameter 4.563" (115.90 mm), 27.06 lb per foot.
| Trade size | NPS 5 · DN 125 |
|---|---|
| Schedule | Schedule 120 |
| Standard | ASME B36.10M (welded and seamless wrought steel pipe) |
| Outside diameter | 5.563" · 141.30 mm |
| Wall thickness | 0.500" · 12.70 mm |
| Inside diameter | 4.563" · 115.90 mm |
| Weight, plain end | 27.06 lb/ft · 40.28 kg/m |
Cross-check: the standard plain-end weight formula W = 10.6802 x t x (OD - t) gives 27.04 lb/ft here, 0.1% from the published 27.06 lb/ft. The published figure is the one printed above.
NPS 5 schedule 120 pipe measures 5.563 in (141.30 mm) across the outside with a 0.500 in wall, so the bore is 4.563 in (115.90 mm). That bore gives a flow area of 16.35 in² and holds 0.8495 US gallons per foot (10.55 litres per metre). The outside diameter is 11.1 times the wall, and the steel itself has a cross-section of 7.953 in² and weighs 27.06 lb per foot plain end. One trade size up, NPS 6 in the same schedule carries 1.45 times the flow area.
Schedule 80 is the next lighter wall at NPS 5: 0.375 in, 0.125 in thinner, which opens the bore to 4.813 in and adds 11% to the flow area, for 23% less weight per foot.
Schedule 160 is the next heavier wall at NPS 5: 0.625 in, 0.125 in thicker, which narrows the bore to 4.313 in and cuts 11% from the flow area, for 22% more weight per foot.
Next trade size up in this schedule: NPS 6 schedule 120, bore 5.501 in.
| Flow area | 16.35 in² |
|---|---|
| Capacity | 0.8495 US gal/ft · 10.55 L/m |
| Metal area | 7.953 in² |
| Moment of inertia | 25.73 in⁴ |
| Section modulus | 9.251 in³ |
| Radius of gyration | 1.799 in |
| Outside surface | 1.456 ft² per foot |
Plain geometry of a hollow circle with OD = 5.563 in and ID = 4.563 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 120 the wall is 0.500 inches, so the bore comes out at 4.563 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 160 | 0.625 | 4.313 | 32.99 |
| Double extra strong (XXS) | 0.750 | 4.063 | 38.59 |
0.500 inches (12.70 mm). The outside diameter is 5.563 inches (141.30 mm) whatever the schedule, so this wall leaves an inside diameter of 4.563 inches.
4.563 inches (115.90 mm). Inside diameter is outside diameter minus twice the wall: 5.563 - 2 x 0.500 = 4.563 inches.
No. NPS 5 is a trade size, not a measurement. The pipe measures 5.563 inches across the outside and 4.563 inches across the bore in this schedule. Only the outside diameter is fixed across schedules.
27.06 pounds per foot plain end (40.28 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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