Dimensions
Cross-check: the standard plain-end weight formula W = 10.6802 x t x (OD - t) gives 6.41 lb/ft here, 0.0% from the published 6.41 lb/ft. The published figure is the one printed above.
NPS 1-1/2 double extra strong (xxs) in numbers
NPS 1-1/2 double extra strong (xxs) pipe measures 1.900 in (48.26 mm) across the outside with a 0.400 in wall, so the bore is 1.100 in (27.96 mm). That bore gives a flow area of 0.9503 in² and holds 0.04937 US gallons per foot (0.6131 litres per metre). The outside diameter is 4.7 times the wall, and the steel itself has a cross-section of 1.885 in² and weighs 6.41 lb per foot plain end. One trade size up, NPS 2 in the same schedule carries 1.87 times the flow area.
Schedule 160 is the next lighter wall at NPS 1-1/2: 0.281 in, 0.119 in thinner, which opens the bore to 1.338 in and adds 48% to the flow area, for 24% less weight per foot.
Next trade size up in this schedule: NPS 2 double extra strong (xxs), bore 1.503 in.
Worked out from the dimensions
Plain geometry of a hollow circle with OD = 1.900 in and ID = 1.100 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 1-1/2 inch pipe is not 1-1/2 inches
Nominal Pipe Size is a label, not a measurement. NPS 1-1/2 pipe has an outside diameter of 1.900 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 0.400 inches, so the bore comes out at 1.100 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 1-1/2
Same outside diameter of 1.900 inches throughout - only the wall and the bore move.
Frequently asked questions
What is the wall thickness of 1-1/2 inch double extra strong (xxs) pipe?
0.400 inches (10.15 mm). The outside diameter is 1.900 inches (48.26 mm) whatever the schedule, so this wall leaves an inside diameter of 1.100 inches.
What is the inside diameter of 1-1/2 inch double extra strong (xxs) pipe?
1.100 inches (27.96 mm). Inside diameter is outside diameter minus twice the wall: 1.900 - 2 x 0.400 = 1.100 inches.
Is 1-1/2 inch pipe actually 1-1/2 inches?
No. NPS 1-1/2 is a trade size, not a measurement. The pipe measures 1.900 inches across the outside and 1.100 inches across the bore in this schedule. Only the outside diameter is fixed across schedules.
How much does 1-1/2 inch double extra strong (xxs) pipe weigh?
6.41 pounds per foot plain end (9.55 kg per metre), for carbon steel. The figure excludes coatings, linings and fittings.
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 5 independent published sources:
Sources disagree here. Published tables split on the last digit here - 10.15 mm (b3610m-ferrobend), 10.15 mm (b3610m-wermac), 10.16 mm (b3610m-wikipedia). The figure printed is 0.4 in (10.15 mm), carried by the majority of the sources. The two readings describe the same wall: they differ by less than a thousandth of an inch, far inside the mill tolerance of minus 12.5 percent on wall thickness.
Last-digit inch walls across the whole table: 0.594, 0.688, 0.719, 0.844, 0.938, 1.094, 1.219, 1.438, 1.969, 2.344 in (b3610m-fbc) against 0.593, 0.687, 0.718, 0.843, 0.937, 1.093, 1.218, 1.437, 1.968, 2.343 in (b3610m-wikipedia). Two families of inch figures are in circulation, one a thousandth of an inch below the other, and they come from rounding the millimetre wall the standard tabulates rather than from any difference in the pipe. The higher family is what the majority of the sources read here carry and is what this site prints; the affected rows say so individually. Nothing turns on the choice: the wall tolerance is minus 12.5 percent, which at a half-inch wall is sixty times the gap.
NPS 14 extra strong (XS): 0.469 in (b3610m-fbc) against 0.500 in (b3610m-etb) against 0.500 in (b3610m-wikipedia). 0.500 in is printed here. Two of the three inch sources give it, both millimetre sources give 12.70 mm which is 0.500 in, and extra strong is a 0.500 in wall at every size from NPS 12 up. The 0.469 in reading looks like a misplaced row in that one chart, but it is recorded rather than deleted.