| NPS | O | tf | X | Ah | Y (THD/SO) | Y (Lap) | Y (WN) | T | B (SO) | B (Lap) | B (WN) | r | Q | D | Bolt Circle Dia. | Bolt Qty | Bolt Hole Dia. | Bolt Dia. |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/2 | 121 | 22.4 | 38 | 21.3 | 32 | 32 | 60 | 22 | 22.4 | 22.9 | 3 | 23.6 | 10 | 82.6 | 4 | 7/8 | 3/4 | |
| 3/4 | 130 | 25.4 | 44 | 26.7 | 35 | 35 | 70 | 25 | 27.7 | 28.2 | 3 | 29 | 11 | 88.9 | 4 | 7/8 | 3/4 | |
| 1 | 149 | 28.4 | 52 | 33.5 | 41 | 41 | 73 | 28 | 34.5 | 35.4 | 3 | 35.8 | 13 | 101.6 | 4 | 1 | 7/8 | |
| 1 1/4 | 159 | 28.4 | 64 | 42.2 | 41 | 41 | 73 | 30 | 43.2 | 43.7 | 5 | 44.4 | 14 | 111.1 | 4 | 1 | 7/8 | |
| 1 1/2 | 178 | 31.8 | 70 | 48.3 | 44 | 44 | 83 | 32 | 49.5 | 50 | 6 | 50.5 | 16 | 124.0 | 4 | 1 1/8 | 1 | |
| 2 | 216 | 38.1 | 105 | 60.5 | 57 | 57 | 102 | 38 | 62 | 62.5 | 8 | 63.5 | 18 | 165.1 | 8 | 1 1/4 | 1 1/8 | |
| 2 1/2 | 244 | 41.1 | 124 | 73.2 | 64 | 64 | 105 | 48 | 74.7 | 75.4 | 8 | 76.2 | 19 | 190.5 | 8 | 1 3/8 | 1 1/4 | |
| 3 | 241 | 38.1 | 127 | 88.9 | 54 | 54 | 102 | 41 | 90.7 | 91.4 | 10 | 92.2 | 190.5 | 8 | 1 | 7/8 | ||
| 4 | 292 | 44.5 | 159 | 114.3 | 70 | 70 | 114 | 48 | 116.1 | 116.8 | 11 | 117.6 | 235.0 | 8 | 1 1/4 | 1 1/8 | ||
| 5 | 349 | 50.8 | 190 | 141.2 | 79 | 79 | 127 | 54 | 143.8 | 144.5 | 11 | 144.5 | 279.4 | 8 | 1 3/8 | 1 1/4 | ||
| 6 | 381 | 55.6 | 235 | 168.4 | 86 | 86 | 140 | 57 | 170.7 | 171.4 | 13 | 171.4 | 317.5 | 8 | 1 1/4 | 1 1/8 | ||
| 8 | 470 | 63.5 | 298 | 219.2 | 102 | 114 | 162 | 64 | 221.5 | 222.2 | 13 | 222.2 | 393.7 | 12 | 1 1/2 | 1 3/8 | ||
| 10 | 546 | 69.8 | 368 | 273 | 108 | 127 | 184 | 71 | 276.4 | 277.4 | 13 | 276.4 | 469.9 | 12 | 1 1/2 | 1 3/8 | ||
| 12 | 610 | 79.2 | 419 | 323.8 | 117 | 143 | 200 | 76 | 327.2 | 328.2 | 13 | 328.7 | 533.4 | 16 | 1 1/2 | 1 3/8 | ||
| 14 | 641 | 85.9 | 451 | 355.6 | 130 | 155 | 213 | 83 | 359.2 | 360.2 | 13 | 360.4 | 558.8 | 20 | 1 5/8 | 1 1/2 | ||
| 16 | 705 | 88.9 | 508 | 406.4 | 133 | 165 | 216 | 86 | 410.5 | 411.2 | 13 | 411.2 | 616.0 | 20 | 1 3/4 | 1 5/8 | ||
| 18 | 787 | 101.6 | 565 | 457.2 | 152 | 190 | 229 | 89 | 461.8 | 462.3 | 13 | 462 | 685.8 | 20 | 2 | 1 7/8 | ||
| 22 | 857 | 108 | 622 | 508 | 159 | 210 | 248 | 92 | 513.1 | 514.4 | 13 | 512.8 | 749.3 | 20 | 2 1/8 | 2 | ||
| 24 | 1041 | 139.7 | 749 | 609.6 | 203 | 267 | 292 | 102 | 616 | 616 | 13 | 614.4 | 901.7 | 20 | 2 5/8 | 2 1/2 |
| NPS | O | tf | X | Ah | Y (THD/SO) | Y (Lap) | Y (WN) | T | B (SO) | B (Lap) | B (WN) | r | Q | D | Bolt Circle Dia. | Bolt Qty | Bolt Hole Dia. | Bolt Dia. |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/2 | 4.75 | 0.88 | 1.5 | 0.84 | 1.25 | 1.25 | 2.38 | 0.88 | 0.88 | 0.9 | 0.12 | 0.93 | 0.38 | 3.25 | 4 | 7/8 | 3/4 | |
| 3/4 | 5.12 | 1 | 1.75 | 1.05 | 1.38 | 1.38 | 2.75 | 1 | 1.09 | 1.11 | 0.12 | 1.14 | 0.44 | 3.5 | 4 | 7/8 | 3/4 | |
| 1 | 5.88 | 1.12 | 2.06 | 1.32 | 1.62 | 1.62 | 2.88 | 1.12 | 1.36 | 1.38 | 0.12 | 1.41 | 0.5 | 4 | 4 | 1 | 7/8 | |
| 1 1/4 | 6.25 | 1.12 | 2.5 | 1.66 | 1.62 | 1.62 | 2.88 | 1.19 | 1.7 | 1.72 | 0.19 | 1.75 | 0.56 | 4.37 | 4 | 1 | 7/8 | |
| 1 1/2 | 7 | 1.25 | 2.75 | 1.9 | 1.75 | 1.75 | 3.25 | 1.25 | 1.95 | 1.97 | 0.25 | 1.99 | 0.62 | 4.88 | 4 | 1 1/8 | 1 | |
| 2 | 8.5 | 1.5 | 4.12 | 2.38 | 2.25 | 2.25 | 4 | 1.5 | 2.44 | 2.46 | 0.31 | 2.5 | 0.69 | 6.5 | 8 | 1 1/4 | 1 1/8 | |
| 2 1/2 | 9.62 | 1.62 | 4.88 | 2.88 | 2.5 | 2.5 | 4.12 | 1.88 | 2.94 | 2.97 | 0.31 | 3 | 0.75 | 7.5 | 8 | 1 3/8 | 1 1/4 | |
| 3 | 9.5 | 1.5 | 5 | 3.5 | 2.12 | 2.12 | 4 | 1.62 | 3.57 | 3.6 | 0.38 | 3.63 | 7.5 | 8 | 1 | 7/8 | ||
| 4 | 11.5 | 1.75 | 6.25 | 4.5 | 2.75 | 2.75 | 4.5 | 1.88 | 4.57 | 4.6 | 0.44 | 4.63 | 9.25 | 8 | 1 1/4 | 1 1/8 | ||
| 5 | 13.75 | 2 | 7.5 | 5.56 | 3.12 | 3.12 | 5 | 2.12 | 5.66 | 5.69 | 0.44 | 5.69 | 11 | 8 | 1 3/8 | 1 1/4 | ||
| 6 | 15 | 2.19 | 9.25 | 6.63 | 3.38 | 3.38 | 5.5 | 2.25 | 6.72 | 6.75 | 0.5 | 6.75 | 12.5 | 8 | 1 1/4 | 1 1/8 | ||
| 8 | 18.5 | 2.5 | 11.75 | 8.63 | 4 | 4.5 | 6.38 | 2.5 | 8.72 | 8.75 | 0.5 | 8.75 | 15.5 | 12 | 1 1/2 | 1 3/8 | ||
| 10 | 21.5 | 2.75 | 14.5 | 10.75 | 4.25 | 5 | 7.25 | 2.81 | 10.88 | 10.92 | 0.5 | 10.88 | 18.5 | 12 | 1 1/2 | 1 3/8 | ||
| 12 | 24 | 3.12 | 16.5 | 12.75 | 4.62 | 5.62 | 7.88 | 3 | 12.88 | 12.92 | 0.5 | 12.94 | 21 | 16 | 1 1/2 | 1 3/8 | ||
| 14 | 25.25 | 3.38 | 17.75 | 14 | 5.12 | 6.12 | 8.38 | 3.25 | 14.14 | 14.18 | 0.5 | 14.19 | 22 | 20 | 1 5/8 | 1 1/2 | ||
| 16 | 27.75 | 3.5 | 20 | 16 | 5.25 | 6.5 | 8.5 | 3.38 | 16.16 | 16.19 | 0.5 | 16.19 | 24.25 | 20 | 1 3/4 | 1 5/8 | ||
| 18 | 31 | 4 | 22.25 | 18 | 6 | 7.5 | 9 | 3.5 | 18.18 | 18.2 | 0.5 | 18.19 | 27 | 20 | 2 | 1 7/8 | ||
| 22 | 33.75 | 4.25 | 24.5 | 20 | 6.25 | 8.25 | 9.75 | 3.62 | 20.2 | 20.25 | 0.5 | 20.19 | 29.5 | 20 | 2 1/8 | 2 | ||
| 24 | 41 | 5.5 | 29.5 | 24 | 8 | 10.5 | 11.5 | 4 | 24.25 | 24.25 | 0.5 | 24.19 | 35.5 | 20 | 2 5/8 | 2 1/2 |
| NPS | SO | THR | LAP | BL | WN |
|---|---|---|---|---|---|
| 1/2 | 6 / 2.7 | 6 / 2.7 | 6 / 2.7 | 4 / 1.8 | 7 / 3.2 |
| 3/4 | 6 / 2.7 | 6 / 2.7 | 6 / 2.7 | 6 / 2.7 | 7 / 3.2 |
| 1 | 7.5 / 3.4 | 7.5 / 3.4 | 7.5 / 3.4 | 9 / 4.1 | 8.5 / 3.9 |
| 1-1/4 | 10 / 4.5 | 10 / 4.5 | 10 / 4.5 | 10 / 4.5 | 10 / 4.5 |
| 1-1/2 | 14 / 6.4 | 14 / 6.4 | 14 / 6.4 | 14 / 6.4 | 14 / 6.4 |
| 2 | 22 / 10.0 | 22 / 10.0 | 21 / 9.5 | 25 / 11.3 | 24 / 10.9 |
| 2-1/2 | 31 / 14.1 | 31 / 14.1 | 25 / 11.3 | 32 / 14.5 | 31 / 14.1 |
| 3 | 36 / 16.3 | 36 / 16.3 | 29 / 13.2 | 35 / 15.9 | 36 / 16.3 |
| 4 | 53 / 24.0 | 53 / 24.0 | 51 / 23.1 | 54 / 24.5 | 53 / 24.0 |
| 5 | 83 / 37.6 | 83 / 37.6 | 81 / 36.7 | 87 / 39.5 | 86 / 39.0 |
| 6 | 110 / 49.9 | 110 / 49.9 | 105 / 47.6 | 115 / 52.2 | 110 / 49.9 |
| 8 | 172 / 78.0 | 172 / 78.0 | 190 / 86.2 | 200 / 90.7 | 187 / 84.8 |
| 10 | 245 / 111.1 | 245 / 111.1 | 277 / 125.6 | 290 / 131.5 | 268 / 121.6 |
| 12 | 326 / 147.9 | 326 / 147.9 | 371 / 168.3 | 415 / 188.2 | 372 / 168.7 |
| 14 | 400 / 181.4 | 400 / 181.4 | 415 / 188.2 | 520 / 235.9 | 562 / 254.9 |
| 16 | 459 / 208.2 | 459 / 208.2 | 488 / 221.4 | 619 / 280.8 | 685 / 310.8 |
| 18 | 647 / 293.5 | 647 / 293.5 | 670 / 304.0 | 880 / 399.2 | 924 / 419.2 |
| 20 | 792 / 359.1 | 792 / 359.1 | 868 / 393.7 | 1107 / 502.2 | 1164 / 528.1 |
| 24 | 1480 / 671.3 | 1480 / 671.3 | 1659 / 752.7 | 2099 / 952.0 | 2107 / 955.6 |
Note: The above data is for reference only. Please refer to the ASME B16.5 standard for design and production.
ASME B16.5 Class 900 Flange Dimensions refer to the dimensional data defined in the ASME B16.5 standard for flanges with a pressure rating of Class 900.
These dimensions specify key parameters for each NPS (Nominal Pipe Size), including flange outside diameter, thickness, number and size of bolt holes, bolt circle diameter, facing dimensions, and weight.
As with all ASME B16.5 flanges, Class 900 dimensions are independent of the material.
This means that whether the flange is manufactured from:
- Carbon steel
- Stainless steel
- Duplex / Super Duplex
- Nickel alloys such as Inconel, Hastelloy, or Monel
- Copper-nickel alloys (CuNi)
The geometric dimensions remain exactly the same.
Different materials only affect the pressure–temperature ratings, not the physical dimensions of the flange.
What is Class 900?
Class 900 is the third-highest pressure rating in the ASME B16.5 system (higher than Class 600, below Class 1500/2500).
It indicates the maximum allowable pressure a flange can withstand at various temperatures.
For this pressure level and above, Weld Neck and RTJ Blind Flanges are the most common.
Typical pressure capability comparison:
- 5–6 times that of Class 150
- ~3 times that of Class 300
- ~1.5 times that of Class 600
For example, using ASTM A182 Gr. F317 flanges:
| Temperature (°C) | Max. Pressure (bar) |
| −29 to 38°C | 148.9 bar |
| 100°C | 126.6bar |
| 200°C | 107.0 bar |
Note: Class 900 does NOT mean 900 psi. It is a rating category, not a direct pressure value.
Characteristics of Class 900 Flanges
- High pressure rating for demanding environments
- Thicker and heavier for increased pressure resistance
- Larger bolt sizes and more bolts for stronger sealing
- RTJ facing often used for high-temperature/high-pressure service
- Widely used in oil & gas, refining, offshore, and chemical industries
- Dimensions follow global ASME B16.5 standards
ASME B16.5 Class 900 flanges provide a robust, reliable solution for high-pressure and high-temperature pipeline systems. Their larger dimensions, thicker structure, increased bolt capacity, and availability in RF or RTJ facings make them ideal for critical applications across the oil & gas, chemical, offshore, and energy sectors.
Because Class 900 flange dimensions are fully standardized and independent of material, engineers and procurement teams can ensure consistent global compatibility and interchangeability.
Whether using carbon steel, stainless steel, duplex, or nickel alloys, the dimensional requirements remain the same—making ASME B16.5 Class 900 flanges a dependable choice for demanding industrial environments.
