ASME B36.10M (welded and seamless wrought steel pipe) · DN 125
Outside diameter 5.563" (141.30 mm), wall 0.750" (19.05 mm), inside diameter 4.063" (103.20 mm), 38.59 lb per foot.
| Trade size | NPS 5 · DN 125 |
|---|---|
| Schedule | Double extra strong (XXS) |
| Standard | ASME B36.10M (welded and seamless wrought steel pipe) |
| Outside diameter | 5.563" · 141.30 mm |
| Wall thickness | 0.750" · 19.05 mm |
| Inside diameter | 4.063" · 103.20 mm |
| Weight, plain end | 38.59 lb/ft · 57.43 kg/m |
Cross-check: the standard plain-end weight formula W = 10.6802 x t x (OD - t) gives 38.55 lb/ft here, 0.1% from the published 38.59 lb/ft. The published figure is the one printed above.
NPS 5 double extra strong (xxs) pipe measures 5.563 in (141.30 mm) across the outside with a 0.750 in wall, so the bore is 4.063 in (103.20 mm). That bore gives a flow area of 12.97 in² and holds 0.6735 US gallons per foot (8.365 litres per metre). The outside diameter is 7.4 times the wall, and the steel itself has a cross-section of 11.34 in² and weighs 38.59 lb per foot plain end. One trade size up, NPS 6 in the same schedule carries 1.45 times the flow area.
Schedule 160 is the next lighter wall at NPS 5: 0.625 in, 0.125 in thinner, which opens the bore to 4.313 in and adds 13% to the flow area, for 15% less weight per foot.
Next trade size up in this schedule: NPS 6 double extra strong (xxs), bore 4.897 in.
| Flow area | 12.97 in² |
|---|---|
| Capacity | 0.6735 US gal/ft · 8.365 L/m |
| Metal area | 11.34 in² |
| Moment of inertia | 33.63 in⁴ |
| Section modulus | 12.09 in³ |
| Radius of gyration | 1.722 in |
| Outside surface | 1.456 ft² per foot |
Plain geometry of a hollow circle with OD = 5.563 in and ID = 4.063 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 double extra strong (xxs) the wall is 0.750 inches, so the bore comes out at 4.063 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 |
| Schedule 160 | 0.625 | 4.313 | 32.99 |
0.750 inches (19.05 mm). The outside diameter is 5.563 inches (141.30 mm) whatever the schedule, so this wall leaves an inside diameter of 4.063 inches.
4.063 inches (103.20 mm). Inside diameter is outside diameter minus twice the wall: 5.563 - 2 x 0.750 = 4.063 inches.
No. NPS 5 is a trade size, not a measurement. The pipe measures 5.563 inches across the outside and 4.063 inches across the bore in this schedule. Only the outside diameter is fixed across schedules.
38.59 pounds per foot plain end (57.43 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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