ASME B36.10M (welded and seamless wrought steel pipe) · DN 200
Outside diameter 8.625" (219.07 mm), wall 0.250" (6.35 mm), inside diameter 8.125" (206.37 mm), 22.38 lb per foot.
| Trade size | NPS 8 · DN 200 |
|---|---|
| Schedule | Schedule 20 |
| 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 | 0.250" · 6.35 mm |
| Inside diameter | 8.125" · 206.37 mm |
| Weight, plain end | 22.38 lb/ft · 33.32 kg/m |
Cross-check: the standard plain-end weight formula W = 10.6802 x t x (OD - t) gives 22.36 lb/ft here, 0.1% from the published 22.38 lb/ft. The published figure is the one printed above.
NPS 8 schedule 20 pipe measures 8.625 in (219.07 mm) across the outside with a 0.250 in wall, so the bore is 8.125 in (206.37 mm). That bore gives a flow area of 51.85 in² and holds 2.693 US gallons per foot (33.45 litres per metre). The outside diameter is 34.5 times the wall, and the steel itself has a cross-section of 6.578 in² and weighs 22.38 lb per foot plain end. One trade size up, NPS 10 in the same schedule carries 1.59 times the flow area.
Schedule 10 is the next lighter wall at NPS 8: 0.148 in, 0.102 in thinner, which opens the bore to 8.329 in and adds 5.1% to the flow area, for 40% less weight per foot.
Schedule 30 is the next heavier wall at NPS 8: 0.277 in, 0.027 in thicker, which narrows the bore to 8.071 in and cuts 1.3% from the flow area, for 10% more weight per foot.
Next trade size up in this schedule: NPS 10 schedule 20, bore 10.250 in.
| Flow area | 51.85 in² |
|---|---|
| Capacity | 2.693 US gal/ft · 33.45 L/m |
| Metal area | 6.578 in² |
| Moment of inertia | 57.72 in⁴ |
| Section modulus | 13.38 in³ |
| Radius of gyration | 2.962 in |
| Outside surface | 2.258 ft² per foot |
Plain geometry of a hollow circle with OD = 8.625 in and ID = 8.125 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 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 20 the wall is 0.250 inches, so the bore comes out at 8.125 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 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 30 | 0.277 | 8.071 | 24.72 |
| 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 |
0.250 inches (6.35 mm). The outside diameter is 8.625 inches (219.07 mm) whatever the schedule, so this wall leaves an inside diameter of 8.125 inches.
8.125 inches (206.37 mm). Inside diameter is outside diameter minus twice the wall: 8.625 - 2 x 0.250 = 8.125 inches.
No. NPS 8 is a trade size, not a measurement. The pipe measures 8.625 inches across the outside and 8.125 inches across the bore in this schedule. Only the outside diameter is fixed across schedules.
22.38 pounds per foot plain end (33.32 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:
Nearby sizes