Pipe schedule wall thickness and matching bore size for ANSI/ASME B16.5 and B16.47 weld neck flanges, by nominal pipe size and schedule.
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Select a pipe schedule to view the matching wall thickness and bore size, including outside diameter, for every nominal pipe size.
| Nominal Pipe Size (in) | Outside Diameter (in) | Wall Thickness (in) | Bore Size (in) |
|---|---|---|---|
| 0.5 | 0.84 | 0.109 | 0.622 |
| 0.75 | 1.05 | 0.113 | 0.824 |
| 1 | 1.315 | 0.133 | 1.049 |
| 1.25 | 1.66 | 0.14 | 1.38 |
| 1.5 | 1.9 | 0.145 | 1.61 |
| 2 | 2.375 | 0.154 | 2.067 |
| 2.5 | 2.875 | 0.203 | 2.469 |
| 3 | 3.5 | 0.216 | 3.068 |
| 3.5 | 4 | 0.226 | 3.548 |
| 4 | 4.5 | 0.237 | 4.026 |
| 4.5 | 5 | 0.247 | 4.506 |
| 5 | 5.563 | 0.258 | 5.047 |
| 6 | 6.625 | 0.28 | 6.065 |
| 7 | 7.625 | 0.301 | 7.023 |
| 8 | 8.625 | 0.322 | 7.981 |
| 9 | 9.625 | 0.342 | 8.941 |
| 10 | 10.75 | 0.365 | 10.02 |
| 11 | 11.75 | 0.375 | 11 |
| 12 | 12.75 | 0.375 | 12 |
| 14 | 14 | 0.375 | 13.25 |
| 16 | 16 | 0.375 | 15.25 |
| 18 | 18 | 0.375 | 17.25 |
| 20 | 20 | 0.375 | 19.25 |
| 22 | 22 | 0.375 | 21.25 |
| 24 | 24 | 0.375 | 23.25 |
| 26 | 26 | 0.375 | 25.25 |
| 28 | 28 | 0.375 | 27.25 |
| 30 | 30 | 0.375 | 29.25 |
| 32 | 32 | 0.375 | 31.25 |
| 34 | 34 | 0.375 | 33.25 |
| 36 | 36 | 0.375 | 35.25 |
| 38 | 38 | 0.375 | 37.25 |
| 40 | 40 | 0.375 | 39.25 |
| 42 | 42 | 0.375 | 41.25 |
| 48 | 48 | 0.375 | 47.25 |
| 54 | 54 | 0.375 | 53.25 |
| 60 | 60 | 0.375 | 59.25 |
We manufacture to your specifications and stock domestic AIS/Buy America and imported materials, with galvanized, epoxy, and additional coatings available. Rubber expansion joints and gaskets are also supplied on request.
A weld neck flange has a long, tapered hub that is butt welded to the pipe, spreading stress evenly and creating a strong, leak-resistant connection. It is the standard choice for high-pressure pipelines and critical process piping, which is why getting the bore right for the pipe schedule you're welding to matters.
Wall thickness is how thick the pipe material itself is; bore size is the resulting inside diameter once that wall thickness is subtracted from the outside diameter. A thicker wall at the same nominal pipe size produces a smaller bore, which is why bore size shrinks as you move from a lighter schedule like 10 to a heavier one like XXH.
This table covers ANSI/ASME B16.5 weld neck flanges through 24 inch and ANSI/ASME B16.47 large-diameter weld neck flanges from 26 inch up, since weld neck bore is set by matching pipe schedule rather than by the flange standard itself.
Pipe schedule is normally specified on project drawings, purchase orders, or pipe markings. When matching an existing weld neck flange to pipe already on hand, measure the pipe's actual wall thickness and compare it to the Wall Thickness column for the nominal pipe size to identify the closest schedule.
Tolerances are applied per ANSI/ASME B16.5 and B16.47, or other applicable standards, depending on the flange and application. This chart is a reference sheet for nominal bore size by schedule, not a substitute for the tolerance tables in those standards.
API International stocks the weld neck flanges you need for your project, and our machine shop can modify stock products for special requirements. Contact API International’s experienced sales team, and we will help you select the right flange and bore for your application.
