Schedule 40S Pipe Dimensions
ASME B36.19M stainless steel pipe in 40S, NPS 1/8 through NPS 12 — with the B36.10M Schedule 40 wall alongside, because the two are routinely swapped by mistake.
- Schedule
- 40S
- Standard
- ASME B36.19M
- Material
- Stainless steel
- Sizes published
- 18 (NPS 1/8 to NPS 12)
- Thinnest wall
- 0.068 in (1.7 mm) at NPS 1/8
- Thickest wall
- 0.375 in (9.5 mm) at NPS 12
Dimensions are given in inches, with the millimetre equivalent beneath in grey.
| Size | DN | Outside diameter | 40S wall | Inside diameter | Weight, empty | vs Schedule 40 |
|---|---|---|---|---|---|---|
| NPS 1/8 | DN 6 | 0.40510.29 mm | 0.0681.73 mm | 0.2696.83 mm | 0.250.37 kg/m | same as Sch 40 |
| NPS 1/4 | DN 8 | 0.54013.72 mm | 0.0882.24 mm | 0.3649.25 mm | 0.430.64 kg/m | same as Sch 40 |
| NPS 3/8 | DN 10 | 0.67517.14 mm | 0.0912.31 mm | 0.49312.52 mm | 0.580.86 kg/m | same as Sch 40 |
| NPS 1/2 | DN 15 | 0.84021.34 mm | 0.1092.77 mm | 0.62215.80 mm | 0.861.29 kg/m | same as Sch 40 |
| NPS 3/4 | DN 20 | 1.05026.67 mm | 0.1132.87 mm | 0.82420.93 mm | 1.151.71 kg/m | same as Sch 40 |
| NPS 1 | DN 25 | 1.31533.40 mm | 0.1333.38 mm | 1.04926.64 mm | 1.702.54 kg/m | same as Sch 40 |
| NPS 1 1/4 | DN 32 | 1.66042.16 mm | 0.1403.56 mm | 1.38035.05 mm | 2.313.43 kg/m | same as Sch 40 |
| NPS 1 1/2 | DN 40 | 1.90048.26 mm | 0.1453.68 mm | 1.61040.89 mm | 2.764.11 kg/m | same as Sch 40 |
| NPS 2 | DN 50 | 2.37560.32 mm | 0.1543.91 mm | 2.06752.50 mm | 3.715.52 kg/m | same as Sch 40 |
| NPS 2 1/2 | DN 65 | 2.87573.02 mm | 0.2035.16 mm | 2.46962.71 mm | 5.888.75 kg/m | same as Sch 40 |
| NPS 3 | DN 80 | 3.50088.90 mm | 0.2165.49 mm | 3.06877.93 mm | 7.6911.44 kg/m | same as Sch 40 |
| NPS 3 1/2 | DN 90 | 4.000101.60 mm | 0.2265.74 mm | 3.54890.12 mm | 9.2513.76 kg/m | same as Sch 40 |
| NPS 4 | DN 100 | 4.500114.30 mm | 0.2376.02 mm | 4.026102.26 mm | 10.9516.30 kg/m | same as Sch 40 |
| NPS 5 | DN 125 | 5.563141.30 mm | 0.2586.55 mm | 5.047128.19 mm | 14.8422.08 kg/m | same as Sch 40 |
| NPS 6 | DN 150 | 6.625168.27 mm | 0.2807.11 mm | 6.065154.05 mm | 19.2628.66 kg/m | same as Sch 40 |
| NPS 8 | DN 200 | 8.625219.07 mm | 0.3228.18 mm | 7.981202.72 mm | 28.9843.13 kg/m | same as Sch 40 |
| NPS 10 | DN 250 | 10.750273.05 mm | 0.3659.27 mm | 10.020254.51 mm | 41.0961.15 kg/m | same as Sch 40 |
| NPS 12 | DN 300 | 12.750323.85 mm | 0.3759.52 mm | 12.000304.80 mm | 50.3174.86 kg/m | Sch 40 is 0.406 |
Weight is plain-end austenitic stainless, taken as 1.5% heavier than the carbon steel formula w = 10.6802 × t × (OD − t) lb/ft.
40S is not the same as Schedule 40 everywhere. The two agree in 17 of the 18 sizes published, and disagree at NPS 12 (0.375 in against 0.406 in). Substituting one for the other in those sizes puts the wrong wall in the line.
Common questions
Is 40S the same as Schedule 40?
Not in every size. They agree in 17 sizes and disagree at NPS 12. The S suffix always signals stainless pipe to ASME B36.19M, which also stops at NPS 12 in this schedule where B36.10M continues.
What sizes does 40S come in?
NPS 1/8 through NPS 12 — 18 sizes. B36.19M is a shorter standard than B36.10M: it publishes 40S and 80S only through NPS 12, and 5S and 10S only through NPS 30. Beyond that, stainless pipe is ordered to a B36.10M schedule.
Why is 40S pipe used?
Stainless costs several times what carbon steel does, so stainless lines are run as thin as the pressure allows. The S-schedules exist to give that thin end of the range a designation — 10S in particular is the workhorse wall for low-pressure stainless process and sanitary piping.