Carbon steel (B36.10M) vs stainless (B36.19M)
Is stainless pipe the same size as carbon steel? — the short answer is that a name is not a measurement. Of the 17 nominal sizes both standards cover, 17 share the same outer diameter and 0 do not.
- Shared sizes
- 17
- Same OD
- 17
- Different OD
- 0
- Only in steel
- 0
| Nominal | ASME B36.10M OD (in) | ASME B36.10M OD (mm) | ASME B36.19M OD (in) | ASME B36.19M OD (mm) | Same outside? | steel walls | stainless walls |
|---|---|---|---|---|---|---|---|
| 1/8 | 0.405 | 10.287 | 0.405 | 10.287 | yes | Sch 40 0.068, Sch 80 0.095, STD 0.068, XS 0.095 | Sch 10S 0.049, Sch 40S 0.068, Sch 80S 0.095 |
| 1/4 | 0.540 | 13.716 | 0.540 | 13.716 | yes | Sch 40 0.088, Sch 80 0.119, STD 0.088, XS 0.119 | Sch 10S 0.065, Sch 40S 0.088, Sch 80S 0.119 |
| 3/8 | 0.675 | 17.145 | 0.675 | 17.145 | yes | Sch 40 0.091, Sch 80 0.126, STD 0.091, XS 0.126 | Sch 10S 0.065, Sch 40S 0.091, Sch 80S 0.126 |
| 1/2 | 0.840 | 21.336 | 0.840 | 21.336 | yes | Sch 10 0.083, Sch 40 0.109, Sch 80 0.147, Sch 160 0.188, STD 0.109, XS 0.147, XXS 0.294 | Sch 5S 0.065, Sch 10S 0.083, Sch 40S 0.109, Sch 80S 0.147 |
| 3/4 | 1.050 | 26.67 | 1.050 | 26.67 | yes | Sch 10 0.083, Sch 40 0.113, Sch 80 0.154, Sch 160 0.219, STD 0.113, XS 0.154, XXS 0.308 | Sch 5S 0.065, Sch 10S 0.083, Sch 40S 0.113, Sch 80S 0.154 |
| 1 | 1.315 | 33.401 | 1.315 | 33.401 | yes | Sch 10 0.109, Sch 40 0.133, Sch 80 0.179, Sch 160 0.250, STD 0.133, XS 0.179, XXS 0.358 | Sch 5S 0.065, Sch 10S 0.109, Sch 40S 0.133, Sch 80S 0.179 |
| 1 1/4 | 1.660 | 42.164 | 1.660 | 42.164 | yes | Sch 40 0.140, Sch 80 0.191, Sch 160 0.250, STD 0.140, XS 0.191, XXS 0.382 | Sch 5S 0.065, Sch 10S 0.109, Sch 40S 0.140, Sch 80S 0.191 |
| 1 1/2 | 1.900 | 48.26 | 1.900 | 48.26 | yes | Sch 10 0.109, Sch 40 0.145, Sch 80 0.200, Sch 160 0.281, STD 0.145, XS 0.200, XXS 0.400 | Sch 5S 0.065, Sch 10S 0.109, Sch 40S 0.145, Sch 80S 0.200 |
| 2 | 2.375 | 60.325 | 2.375 | 60.325 | yes | Sch 10 0.109, Sch 40 0.154, Sch 80 0.218, Sch 160 0.344, STD 0.154, XS 0.218, XXS 0.436 | Sch 5S 0.065, Sch 10S 0.109, Sch 40S 0.154, Sch 80S 0.218 |
| 2 1/2 | 2.875 | 73.025 | 2.875 | 73.025 | yes | Sch 40 0.203, Sch 80 0.276, Sch 160 0.375, STD 0.203, XS 0.276, XXS 0.552 | Sch 5S 0.083, Sch 10S 0.120, Sch 40S 0.203, Sch 80S 0.276 |
| 3 | 3.500 | 88.9 | 3.500 | 88.9 | yes | Sch 10 0.120, Sch 40 0.216, Sch 80 0.300, Sch 160 0.438, STD 0.216, XS 0.300, XXS 0.600 | Sch 5S 0.083, Sch 10S 0.120, Sch 40S 0.216, Sch 80S 0.300 |
| 4 | 4.500 | 114.3 | 4.500 | 114.3 | yes | Sch 10 0.120, Sch 40 0.237, Sch 80 0.337, Sch 120 0.438, Sch 160 0.531, STD 0.237, XS 0.337, XXS 0.674 | Sch 5S 0.083, Sch 10S 0.120, Sch 40S 0.237, Sch 80S 0.337 |
| 5 | 5.563 | 141.3 | 5.563 | 141.3 | yes | Sch 40 0.258, Sch 80 0.375, Sch 120 0.500, Sch 160 0.625, STD 0.258, XS 0.375, XXS 0.750 | Sch 5S 0.109, Sch 10S 0.134, Sch 40S 0.258, Sch 80S 0.375 |
| 6 | 6.625 | 168.275 | 6.625 | 168.275 | yes | Sch 10 0.134, Sch 40 0.280, Sch 80 0.432, Sch 120 0.562, Sch 160 0.719, STD 0.280, XS 0.432, XXS 0.864 | Sch 5S 0.109, Sch 10S 0.134, Sch 40S 0.280, Sch 80S 0.432 |
| 8 | 8.625 | 219.075 | 8.625 | 219.075 | yes | Sch 10 0.148, Sch 20 0.250, Sch 30 0.277, Sch 40 0.322, Sch 60 0.406, Sch 80 0.500, Sch 100 0.594, Sch 120 0.719, Sch 140 0.812, Sch 160 0.906, STD 0.322, XS 0.500, XXS 0.875 | Sch 5S 0.109, Sch 10S 0.148, Sch 40S 0.322, Sch 80S 0.500 |
| 10 | 10.750 | 273.05 | 10.750 | 273.05 | yes | Sch 10 0.165, Sch 20 0.250, Sch 30 0.307, Sch 40 0.365, Sch 60 0.500, Sch 80 0.594, Sch 100 0.719, Sch 120 0.844, Sch 140 1.000, Sch 160 1.125, STD 0.365, XS 0.500, XXS 1.000 | Sch 5S 0.134, Sch 10S 0.165, Sch 40S 0.365, Sch 80S 0.500 |
| 12 | 12.750 | 323.85 | 12.750 | 323.85 | yes | Sch 10 0.180, Sch 20 0.250, Sch 30 0.330, Sch 40 0.406, Sch 60 0.562, Sch 80 0.688, Sch 100 0.844, Sch 120 1.000, Sch 140 1.125, Sch 160 1.312, STD 0.375, XS 0.500, XXS 1.000 | Sch 5S 0.156, Sch 10S 0.180, Sch 40S 0.375 |
Why the two do not line up
steel and stainless sizes come from different habits of naming. Where the plastic standard grew out of “iron pipe size”, the OD is deliberately the steel OD so that fittings share a footprint; where it grew out of tubing practice, the OD is its own number and the nominal size is closer to the bore. Nothing in the name tells you which case you are in — the table does.
Full lists: ASME B36.10M chart · ASME B36.19M chart. Each size page lists the sources for its own numbers.