ASME B36.10M (welded and seamless wrought steel pipe) · DN 200
Outside diameter 8.625" (219.07 mm), wall 0.277" (7.04 mm), inside diameter 8.071" (204.99 mm), 24.72 lb per foot.
| Trade size | NPS 8 · DN 200 |
|---|---|
| Schedule | Schedule 30 |
| Standard | ASME B36.10M (welded and seamless wrought steel pipe) |
| Outside diameter | 8.625" · 219.07 mm · designated 219.1 mm in the metric column |
| Wall thickness | 0.277" · 7.04 mm |
| Inside diameter | 8.071" · 204.99 mm |
| Weight, plain end | 24.72 lb/ft · 36.82 kg/m |
Cross-check: the standard plain-end weight formula W = 10.6802 x t x (OD - t) gives 24.70 lb/ft here, 0.1% from the published 24.72 lb/ft. The published figure is the one printed above.
NPS 8 schedule 30 pipe measures 8.625 in (219.07 mm) across the outside with a 0.277 in wall, so the bore is 8.071 in (204.99 mm). That bore gives a flow area of 51.16 in² and holds 2.658 US gallons per foot (33.01 litres per metre). The outside diameter is 31.1 times the wall, and the steel itself has a cross-section of 7.265 in² and weighs 24.72 lb per foot plain end. One trade size up, NPS 10 in the same schedule carries 1.58 times the flow area.
Schedule 20 is the next lighter wall at NPS 8: 0.250 in, 0.027 in thinner, which opens the bore to 8.125 in and adds 1.3% to the flow area, for 9.5% less weight per foot.
Schedule 40 is the next heavier wall at NPS 8: 0.322 in, 0.045 in thicker, which narrows the bore to 7.981 in and cuts 2.2% from the flow area, for 16% more weight per foot.
Next trade size up in this schedule: NPS 10 schedule 30, bore 10.136 in.
| Flow area | 51.16 in² |
|---|---|
| Capacity | 2.658 US gal/ft · 33.01 L/m |
| Metal area | 7.265 in² |
| Moment of inertia | 63.35 in⁴ |
| Section modulus | 14.69 in³ |
| Radius of gyration | 2.953 in |
| Outside surface | 2.258 ft² per foot |
Plain geometry of a hollow circle with OD = 8.625 in and ID = 8.071 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 8 pipe has an outside diameter of 8.625 inches, and it keeps that outside diameter in every schedule made. What the schedule number changes is the wall: at schedule 30 the wall is 0.277 inches, so the bore comes out at 8.071 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 8.625 inches throughout - only the wall and the bore move.
| Schedule | Wall (in) | ID (in) | Weight (lb/ft) |
|---|---|---|---|
| Schedule 5 · 5S | 0.109 | 8.407 | 9.92 |
| Schedule 10 · 10S | 0.148 | 8.329 | 13.41 |
| Schedule 20 | 0.250 | 8.125 | 22.38 |
| Schedule 40 · STD, 40S | 0.322 | 7.981 | 28.58 |
| Schedule 60 | 0.406 | 7.813 | 35.67 |
| Schedule 80 · XS, 80S | 0.500 | 7.625 | 43.43 |
| Schedule 100 | 0.594 | 7.437 | 51.00 |
| Schedule 120 | 0.719 | 7.187 | 60.77 |
| Schedule 140 | 0.812 | 7.001 | 67.82 |
| Schedule 160 | 0.906 | 6.813 | 74.76 |
| Double extra strong (XXS) | 0.875 | 6.875 | 72.49 |
0.277 inches (7.04 mm). The outside diameter is 8.625 inches (219.07 mm) whatever the schedule, so this wall leaves an inside diameter of 8.071 inches.
8.071 inches (204.99 mm). Inside diameter is outside diameter minus twice the wall: 8.625 - 2 x 0.277 = 8.071 inches.
No. NPS 8 is a trade size, not a measurement. The pipe measures 8.625 inches across the outside and 8.071 inches across the bore in this schedule. Only the outside diameter is fixed across schedules.
24.72 pounds per foot plain end (36.82 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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