Dimensions
Cross-check: the standard plain-end weight formula W = 10.6802 x t x (OD - t) gives 353.61 lb/ft here, 0.1% from the published 353.94 lb/ft. The published figure is the one printed above.
NPS 22 schedule 120 in numbers
NPS 22 schedule 120 pipe measures 22.000 in (558.80 mm) across the outside with a 1.625 in wall, so the bore is 18.750 in (476.24 mm). That bore gives a flow area of 276.1 in² and holds 14.34 US gallons per foot (178.1 litres per metre). The outside diameter is 13.5 times the wall, and the steel itself has a cross-section of 104.0 in² and weighs 353.94 lb per foot plain end. One trade size up, NPS 24 in the same schedule carries 1.18 times the flow area.
Schedule 100 is the next lighter wall at NPS 22: 1.375 in, 0.250 in thinner, which opens the bore to 19.250 in and adds 5.4% to the flow area, for 14% less weight per foot.
Schedule 140 is the next heavier wall at NPS 22: 1.875 in, 0.250 in thicker, which narrows the bore to 18.250 in and cuts 5.3% from the flow area, for 14% more weight per foot.
Next trade size up in this schedule: NPS 24 schedule 120, bore 20.376 in.
Worked out from the dimensions
Plain geometry of a hollow circle with OD = 22.000 in and ID = 18.750 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.
Why 22 inch pipe is not 22 inches
Nominal Pipe Size is a label, not a measurement. NPS 22 pipe has an outside diameter of 22.000 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 1.625 inches, so the bore comes out at 18.750 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.
Other schedules in NPS 22
Same outside diameter of 22.000 inches throughout - only the wall and the bore move.
Frequently asked questions
What is the wall thickness of 22 inch schedule 120 pipe?
1.625 inches (41.28 mm). The outside diameter is 22.000 inches (558.80 mm) whatever the schedule, so this wall leaves an inside diameter of 18.750 inches.
What is the inside diameter of 22 inch schedule 120 pipe?
18.750 inches (476.24 mm). Inside diameter is outside diameter minus twice the wall: 22.000 - 2 x 1.625 = 18.750 inches.
Is 22 inch pipe actually 22 inches?
No. NPS 22 is a trade size, not a measurement. The pipe measures 22.000 inches across the outside and 18.750 inches across the bore in this schedule. Only the outside diameter is fixed across schedules.
How much does 22 inch schedule 120 pipe weigh?
353.94 pounds per foot plain end (527.05 kg per metre), for carbon steel. The figure excludes coatings, linings and fittings.
Not published here
2 schedules at NPS 22 appear in only one of the published tables cross-checked for this section, so they are named rather than printed: 40S, 80S. Everything shown above carries at least two independent sources.
Where this table stops
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.
Where these figures come from
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 4 independent published sources: