| NPS | Flange OD | Thickness | Bolt circle | No. of bolts | Bolt dia. |
|---|---|---|---|---|---|
| 1/2" | 88.9 | 11.2 | 60.3 | 4 | 1/2" |
| 3/4" | 98.6 | 12.7 | 69.9 | 4 | 1/2" |
| 1" | 107.9 | 14.2 | 79.4 | 4 | 1/2" |
| 1-1/4" | 117.3 | 15.7 | 88.9 | 4 | 1/2" |
| 1-1/2" | 127.0 | 17.5 | 98.6 | 4 | 1/2" |
| 2" | 152.4 | 19.1 | 120.7 | 4 | 5/8" |
| 2-1/2" | 177.8 | 22.3 | 139.7 | 4 | 5/8" |
| 3" | 190.5 | 23.9 | 152.4 | 4 | 5/8" |
| 3-1/2" | 215.9 | 23.9 | 177.8 | 8 | 5/8" |
| 4" | 228.6 | 23.9 | 190.5 | 8 | 5/8" |
| 5" | 254.0 | 23.9 | 215.9 | 8 | 3/4" |
| 6" | 279.4 | 25.4 | 241.3 | 8 | 3/4" |
| 8" | 342.9 | 28.6 | 298.5 | 8 | 3/4" |
| 10" | 406.4 | 30.2 | 361.9 | 12 | 7/8" |
| 12" | 482.6 | 31.8 | 431.8 | 12 | 7/8" |
| 14" | 533.4 | 35.0 | 476.3 | 12 | 1" |
| 16" | 596.9 | 36.6 | 539.8 | 16 | 1" |
| 18" | 635.0 | 39.7 | 577.9 | 16 | 1-1/8" |
| 20" | 698.5 | 42.9 | 635.0 | 20 | 1-1/8" |
| 24" | 812.8 | 47.7 | 749.3 | 20 | 1-1/4" |
| NPS | Flange OD | Thickness | Bolt circle | No. of bolts | Bolt dia. |
|---|---|---|---|---|---|
| 1/2" | 95.2 | 14.2 | 66.7 | 4 | 1/2" |
| 3/4" | 117.3 | 15.7 | 82.6 | 4 | 5/8" |
| 1" | 124.0 | 17.5 | 88.9 | 4 | 5/8" |
| 1-1/4" | 133.4 | 19.1 | 98.6 | 4 | 5/8" |
| 1-1/2" | 155.4 | 20.7 | 114.3 | 4 | 3/4" |
| 2" | 165.1 | 22.3 | 127.0 | 8 | 5/8" |
| 2-1/2" | 190.5 | 25.4 | 149.2 | 8 | 3/4" |
| 3" | 209.6 | 28.6 | 168.3 | 8 | 3/4" |
| 3-1/2" | 228.6 | 30.2 | 184.2 | 8 | 3/4" |
| 4" | 254.0 | 31.8 | 200.0 | 8 | 3/4" |
| 5" | 279.4 | 35.0 | 235.0 | 8 | 3/4" |
| 6" | 317.5 | 36.6 | 269.9 | 12 | 3/4" |
| 8" | 381.0 | 41.3 | 330.2 | 12 | 7/8" |
| 10" | 444.5 | 47.7 | 387.4 | 16 | 1" |
| 12" | 520.7 | 50.8 | 450.8 | 16 | 1-1/8" |
| 14" | 584.2 | 54.0 | 514.4 | 20 | 1-1/8" |
| 16" | 641.4 | 57.2 | 571.5 | 20 | 1-1/4" |
| 18" | 704.9 | 60.4 | 628.6 | 24 | 1-1/4" |
| 20" | 774.7 | 63.5 | 685.8 | 24 | 1-1/4" |
| 24" | 914.4 | 69.9 | 812.8 | 24 | 1-1/2" |
Indicative values for guidance only. Always confirm against the governing standard and the Material Test Certificate before ordering or designing.
How to use this
Class is not pressure. Class 150, 300, 600 and so on are reference numbers. The allowable pressure depends on the material group and the temperature and is read from the pressure-temperature tables in ASME B16.5. A Class 150 carbon steel flange is good for roughly 19.6 bar at ambient but only about 10 bar at 300 °C.
Bolt circle is what makes flanges interchangeable. Because the bolt circle, count and diameter are fixed by class and size, a weld neck and a slip-on of the same class and NPS will bolt to each other, and to a blind, regardless of material.
Stud length. Choose the length so that two to three threads protrude beyond each nut after tightening. Give us the flange class, NPS, facing and gasket type and we will work out the stud set for you.
Bolting material. The standard sets are A193 B7 with A194 2H nuts for carbon service, A193 B8M with A194 8M for stainless, and A320 L7 for low temperature. See fasteners.
Sizes above NPS 24 are covered by ASME B16.47 Series A and Series B, which are not interchangeable with each other. Ask us for those dimensions.
