PipeData

Schedule 120 Pipe Dimensions

Wall thickness, bore and plain-end weight for all 12 sizes ASME B36.10M publishes in schedule 120, NPS 4 through NPS 24.

Schedule
Schedule 120
Sizes published
12 (NPS 4 to NPS 24)
Thinnest wall
0.438 in (11.1 mm) at NPS 4
Thickest wall
1.812 in (46.0 mm) at NPS 24
Standard
ASME B36.10M

Where schedule 120 is used

Schedule 120 is a heavy wall between Schedule 80 and Schedule 160. It is used in high-pressure steam and process piping and is less widely stocked than either of its neighbours.

Pipe wall thickness to scale, Schedule 120Pipe cross-sections drawn to scale at the same outside diameter so the wall thicknesses can be compared. NPS 4: 0.438 in wall on 4.500 in OD; NPS 14: 1.094 in wall on 14.000 in OD; NPS 24: 1.812 in wall on 24.000 in ODNPS 40.438 in wall on 4.500 in ODNPS 141.094 in wall on 14.000 in ODNPS 241.812 in wall on 24.000 in OD
Schedule 120 in three sizes, each drawn to its own scale. The sections are drawn at the same width so that the wall can be compared with the diameter it belongs to. The wall gets thicker as the size goes up, but it takes up a smaller share of the pipe.

Schedule 120 in every size

Dimensions are given in inches, with the millimetre equivalent beneath in grey.

ASME B36.10M schedule 120 dimensions.
SizeDNOutside diameterWall thicknessInside diameterWeight, emptyWater (US gal/ft)This size
NPS 4DN 1004.500114.30 mm0.43811.13 mm3.62492.05 mm19.0228.30 kg/m0.536all schedules →
NPS 5DN 1255.563141.30 mm0.50012.70 mm4.563115.90 mm27.0640.27 kg/m0.849all schedules →
NPS 6DN 1506.625168.27 mm0.56214.27 mm5.501139.73 mm36.4354.21 kg/m1.235all schedules →
NPS 8DN 2008.625219.07 mm0.71918.26 mm7.187182.55 mm60.7790.43 kg/m2.107all schedules →
NPS 10DN 25010.750273.05 mm0.84421.44 mm9.062230.17 mm89.38133.01 kg/m3.350all schedules →
NPS 12DN 30012.750323.85 mm1.00025.40 mm10.750273.05 mm125.61186.92 kg/m4.715all schedules →
NPS 14DN 35014.000355.60 mm1.09427.79 mm11.812300.02 mm150.93224.61 kg/m5.693all schedules →
NPS 16DN 40016.000406.40 mm1.21930.96 mm13.562344.47 mm192.61286.64 kg/m7.504all schedules →
NPS 18DN 45018.000457.20 mm1.37534.92 mm15.250387.35 mm244.37363.66 kg/m9.489all schedules →
NPS 20DN 50020.000508.00 mm1.50038.10 mm17.000431.80 mm296.65441.46 kg/m11.791all schedules →
NPS 22DN 55022.000558.80 mm1.62541.27 mm18.750476.25 mm353.94526.72 kg/m14.344all schedules →
NPS 24DN 60024.000609.60 mm1.81246.02 mm20.376517.55 mm429.79639.59 kg/m16.939all schedules →

Weight is plain-end carbon steel, w = 10.69 × t × (OD − t) lb/ft.

How the wall changes with size

The wall in schedule 120 is 0.438 in (11.1 mm) at NPS 4 and 1.812 in (46.0 mm) at NPS 24. Measured against the pipe it belongs to, that is 9.7% of the outside diameter at the small end and 7.5% at the large end, so the wall does not keep pace with the diameter. The pressure the pipe will hold moves the same way. On the basis used throughout this site (ASME B31.3, S = 20,000 psi, nominal wall, no corrosion allowance) schedule 120 holds about 4,222 psig at NPS 4 and about 3,140 psig at NPS 22. A schedule is therefore chosen size by size, from a calculation, and not once for a whole plant.

In this schedule the wall thickness coincides with XXS in NPS 12. Outside those sizes it does not, so never substitute one designation for the other without checking the number.

Guides and comparisons for this page

What a pipe schedule actually isWhy a schedule is a wall series and not a thickness.Pipe wall thickness calculationBarlow and ASME B31.3, corrosion allowance and mill tolerance.Pipe sizing by flow rate and velocityTurn a flow rate into a line size using velocity limits.

Common questions

What sizes is schedule 120 pipe made in?

ASME B36.10M publishes schedule 120 in 12 sizes, from NPS 4 through NPS 24. Wall thickness runs from 0.438 in (11.1 mm) at the small end to 1.812 in (46.0 mm) at the large end.

Does schedule 120 mean the same wall thickness in every size?

No. It is a series, not a thickness. The wall is 0.438 in (11.1 mm) at NPS 4 and 1.812 in (46.0 mm) at NPS 24, so the thickness always has to be read off the table for the size in hand.

How pipe schedules work →