| NPS | O | tf | tf(lap) | X | Ah | Y(THD/ SO/SW) | Y (LAP) | Y (WN) | T | B (SO) | B (LAP) | B (WN) | r | D | Bolt Circle Dia. | Bolt Qty | Bolt Hole Dia. | Bolt Dia. |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/2 | 89 | 9.7 | 11.2 | 30 | 21.3 | 14 | 16 | 46 | 16 | 22.4 | 22.9 | 15.7 | 3 | 10 | 66.5 | 4 | 5/8 | 1/2 |
| 3/4 | 99 | 11.2 | 12.7 | 38 | 26.7 | 14 | 16 | 51 | 16 | 27.7 | 28.2 | 20.8 | 3 | 11 | 82.6 | 4 | 3/4 | 5/8 |
| 1 | 108 | 12.7 | 14.2 | 49 | 33.5 | 16 | 18 | 54 | 18 | 34.5 | 35.1 | 26.7 | 3 | 13 | 88.9 | 4 | 3/4 | 5/8 |
| 1 1/4 | 117 | 14.2 | 15.7 | 59 | 42.2 | 19 | 21 | 56 | 21 | 43.2 | 43.7 | 35.1 | 5 | 14 | 98.6 | 4 | 3/4 | 5/8 |
| 1 1/2 | 127 | 15.9 | 17.5 | 65 | 48.3 | 21 | 22 | 60 | 22 | 49.5 | 50 | 40.9 | 6 | 16 | 114.3 | 4 | 7/8 | 3/4 |
| 2 | 152 | 17.5 | 19 | 78 | 60.5 | 24 | 25 | 62 | 25 | 61.9 | 62.5 | 52.6 | 8 | 18 | 127.0 | 8 | 3/4 | 5/8 |
| 2 1/2 | 178 | 20.6 | 22.4 | 90 | 73.2 | 27 | 28 | 68 | 28 | 74.7 | 75.4 | 62.7 | 8 | 19 | 149.4 | 8 | 7/8 | 3/4 |
| 3 | 190 | 22.4 | 23.9 | 108 | 88.9 | 28 | 30 | 68 | 30 | 90.7 | 91.4 | 78 | 10 | 21 | 168.1 | 8 | 7/8 | 3/4 |
| 3 1/2 | 216 | 22.4 | 23.9 | 122 | 101.6 | 30 | 32 | 70 | 32 | 103.4 | 104.1 | 90.2 | 10 | 184.2 | 8 | 7/8 | 3/4 | |
| 4 | 229 | 22.4 | 23.9 | 135 | 114.3 | 32 | 33 | 75 | 33 | 116.1 | 116.8 | 102.4 | 11 | 200.2 | 8 | 7/8 | 3/4 | |
| 5 | 254 | 22.4 | 23.9 | 164 | 141.2 | 35 | 37 | 87 | 37 | 143.8 | 144.5 | 128.3 | 11 | 235.0 | 8 | 7/8 | 3/4 | |
| 6 | 279 | 23.9 | 25.4 | 192 | 168.4 | 38 | 40 | 87 | 40 | 170.7 | 171.4 | 154.2 | 13 | 269.7 | 12 | 7/8 | 3/4 | |
| 8 | 343 | 26.9 | 28.4 | 246 | 219.2 | 43 | 44 | 100 | 44 | 221.5 | 222.2 | 202.7 | 13 | 330.2 | 12 | 1 | 7/8 | |
| 10 | 406 | 28.4 | 30.2 | 305 | 273 | 48 | 49 | 100 | 49 | 276.4 | 277.4 | 254.5 | 13 | 387.4 | 16 | 1 1/8 | 1 | |
| 12 | 483 | 30.2 | 31.8 | 365 | 323.8 | 54 | 56 | 113 | 56 | 327.2 | 328.2 | 304.8 | 13 | 450.8 | 16 | 1 1/4 | 1 1/8 | |
| 14 | 553 | 33.3 | 35.1 | 400 | 355.6 | 56 | 79 | 125 | 57 | 359.2 | 360.2 | 13 | 514.4 | 20 | 1 1/4 | 1 1/8 | ||
| 16 | 597 | 35.1 | 36.6 | 457 | 406.4 | 62 | 87 | 125 | 64 | 410.5 | 411.2 | 13 | 571.5 | 20 | 1 3/8 | 1 1/4 | ||
| 18 | 635 | 38.1 | 39.6 | 505 | 457.2 | 67 | 97 | 138 | 68 | 461.8 | 462.3 | 13 | 628.6 | 24 | 1 3/8 | 1 1/4 | ||
| 20 | 698 | 41.1 | 42.9 | 559 | 508 | 71 | 103 | 143 | 73 | 513.1 | 514.4 | 13 | 685.8 | 24 | 1 3/8 | 1 1/4 | ||
| 22 | 749 | 44.4 | 46 | 610 | 558.8 | 78 | 108 | 148 | 564.4 | 565.2 | 13 | 743.0 | 24 | 1 5/8 | 1 1/2 | |||
| 24 | 813 | 46 | 47.8 | 663 | 609.6 | 81 | 111 | 151 | 83 | 616 | 616 | 13 | 812.8 | 24 | 1 5/8 | 1 1/2 |
| NPS | O | tf | tf(lap) | X | Ah | Y (THD /SO/SW) | Y (lap) | Y (W.N.) | T | B (SO) | B (lap) | B (WN) | r | Q | D | Bolt Circle Dia. | Bolt Qty | Bolt Hole Dia. | Bolt Dia. |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/2 | 3.75 | 0.5 | 0.56 | 1.5 | 0.84 | 0.81 | 0.88 | 2 | 0.62 | 0.88 | 0.9 | 0.62 | 0.12 | 0.93 | 0.38 | 2.62 | 5/8 | 4 | 1/2 |
| 3/4 | 4.62 | 0.56 | 0.62 | 1.88 | 1.05 | 0.94 | 1 | 2.19 | 0.62 | 1.09 | 1.11 | 0.82 | 0.12 | 1.14 | 0.44 | 3.25 | 3/4 | 4 | 5/8 |
| 1 | 4.88 | 0.62 | 0.69 | 2.12 | 1.32 | 1 | 1.06 | 2.38 | 0.69 | 1.36 | 1.38 | 1.05 | 0.12 | 1.41 | 0.5 | 3.5 | 3/4 | 4 | 5/8 |
| 1 1/4 | 5.25 | 0.69 | 0.75 | 2.5 | 1.66 | 1 | 1.06 | 2.5 | 0.81 | 1.7 | 1.72 | 1.38 | 0.19 | 1.75 | 0.56 | 3.88 | 3/4 | 4 | 5/8 |
| 1 1/2 | 6.12 | 0.75 | 0.81 | 2.75 | 1.9 | 1.13 | 1.19 | 2.63 | 0.88 | 1.95 | 1.97 | 1.61 | 0.25 | 1.98 | 0.62 | 4.5 | 7/8 | 4 | 3/4 |
| 2 | 6.5 | 0.81 | 0.88 | 3.31 | 2.38 | 1.25 | 1.31 | 2.69 | 1.12 | 2.44 | 2.46 | 2.07 | 0.31 | 2.5 | 0.69 | 5 | 3/4 | 8 | 5/8 |
| 2 1/2 | 7.5 | 0.94 | 1 | 3.94 | 2.88 | 1.44 | 1.5 | 2.94 | 1.25 | 2.94 | 2.97 | 2.47 | 0.31 | 3 | 0.75 | 5.88 | 7/8 | 8 | 3/4 |
| 3 | 8.25 | 1.06 | 1.12 | 4.62 | 3.5 | 1.5 | 1.69 | 3.06 | 1.25 | 3.57 | 3.6 | 3.07 | 0.38 | 3.63 | 0.81 | 6.62 | 7/8 | 8 | 3/4 |
| 3 1/2 | 9 | 1.12 | 1.19 | 5.25 | 4 | 1.69 | 1.75 | 3.13 | 1.44 | 4.07 | 4.1 | 3.55 | 0.38 | 4.13 | 7.25 | 7/8 | 8 | 3/4 | |
| 4 | 10 | 1.19 | 1.25 | 5.75 | 4.5 | 1.82 | 1.88 | 3.32 | 1.44 | 4.57 | 4.6 | 4.03 | 0.44 | 4.63 | 7.88 | 7/8 | 8 | 3/4 | |
| 5 | 11 | 1.31 | 1.38 | 7 | 5.56 | 1.94 | 2 | 3.82 | 1.69 | 5.66 | 5.69 | 5.05 | 0.44 | 5.69 | 9.25 | 7/8 | 8 | 3/4 | |
| 6 | 12.5 | 1.38 | 1.44 | 8.12 | 6.63 | 2 | 2.06 | 3.82 | 1.81 | 6.72 | 6.75 | 6.07 | 0.5 | 6.75 | 10.62 | 7/8 | 12 | 3/4 | |
| 8 | 15 | 1.56 | 1.62 | 10.25 | 8.63 | 2.38 | 2.44 | 4.32 | 2 | 8.72 | 8.75 | 7.98 | 0.5 | 8.75 | 13 | 1 | 12 | 7/8 | |
| 10 | 17.5 | 1.81 | 1.88 | 12 | 10.75 | 2.56 | 3.75 | 4.56 | 2.19 | 10.88 | 10.92 | 10.02 | 0.5 | 10.88 | 15.25 | 1 1/8 | 16 | 1 | |
| 12 | 20.5 | 1.94 | 2 | 14.75 | 12.75 | 2.82 | 4 | 5.06 | 2.38 | 12.88 | 12.92 | 12 | 0.5 | 12.94 | 17.75 | 1 1/4 | 16 | 1 1/8 | |
| 14 | 23 | 2.06 | 2.12 | 16.75 | 14 | 2.94 | 4.38 | 5.56 | 2.5 | 14.14 | 14.18 | 0.5 | 14.19 | 20.25 | 1 1/4 | 20 | 1 1/4 | ||
| 16 | 25.5 | 2.19 | 2.25 | 19 | 16 | 3.19 | 4.75 | 5.69 | 2.69 | 16.16 | 16.19 | 0.5 | 16.19 | 22.5 | 1 3/8 | 20 | 1 1/4 | ||
| 18 | 28 | 2.31 | 2.38 | 21 | 18 | 3.44 | 5.12 | 6.19 | 2.75 | 18.18 | 18.2 | 0.5 | 18.19 | 24.75 | 1 3/8 | 24 | 1 1/4 | ||
| 20 | 30.5 | 2.44 | 2.5 | 23.12 | 20 | 3.69 | 5.5 | 6.32 | 2.88 | 20.2 | 20.25 | 0.5 | 20.19 | 27 | 1 5/8 | 24 | 1 1/2 | ||
| 22 | 33 | 2.56 | 2.62 | 25.25 | 22 | 3.94 | 5.69 | 6.44 | 22.22 | 22.25 | 0.5 | 29.25 | 1 5/8 | 24 | 1 1/2 | ||||
| 24 | 36 | 2.69 | 2.75 | 27.62 | 24 | 4.13 | 6 | 6.56 | 3.25 | 24.25 | 24.25 | 0.5 | 24.19 | 32 | 1 5/8 | 24 | 1 1/2 |
| NPS | SO | THR | SW | LAP | BL | WN |
|---|---|---|---|---|---|---|
| 1/2 | 2 / 0.91 | 2 / 0.91 | 3 / 1.36 | 2 / 0.91 | 2 / 0.91 | 2 / 0.91 |
| 3/4 | 3 / 1.36 | 3 / 1.36 | 3 / 1.36 | 3 / 1.36 | 3 / 1.36 | 3 / 1.36 |
| 1 | 3 / 1.36 | 3 / 1.36 | 3 / 1.36 | 3 / 1.36 | 4 / 1.81 | 4 / 1.81 |
| 1-1/4 | 4.5 / 2.04 | 4.5 / 2.04 | 4 / 1.81 | 4.5 / 2.04 | 6 / 2.72 | 5 / 2.27 |
| 1-1/2 | 6.5 / 2.95 | 6.5 / 2.95 | 6 / 2.72 | 6.5 / 2.95 | 7 / 3.18 | 7 / 3.18 |
| 2 | 7 / 3.18 | 7 / 3.18 | 7 / 3.18 | 7 / 3.18 | 8 / 3.63 | 9 / 4.08 |
| 2-1/2 | 10 / 4.54 | 10 / 4.54 | 10 / 4.54 | 10 / 4.54 | 12 / 5.44 | 12 / 5.44 |
| 3 | 13 / 5.90 | 14 / 6.35 | 13 / 5.90 | 14.5 / 6.58 | 16 / 7.26 | 18 / 8.16 |
| 3-1/2 | 17 / 7.71 | 17 / 7.71 | 17 / 7.71 | 17 / 7.71 | 21 / 9.53 | 20 / 9.07 |
| 4 | 23.5 / 10.66 | 24 / 10.89 | 22 / 9.98 | 24 / 10.89 | 28 / 12.70 | 26.5 / 12.02 |
| 5 | 29 / 13.15 | 31 / 14.06 | 28 / 12.70 | 28 / 12.70 | 37 / 16.78 | 36 / 16.33 |
| 6 | 39 / 17.69 | 39 / 17.69 | 39 / 17.69 | 39 / 17.69 | 50 / 22.68 | 45 / 20.41 |
| 8 | 58 / 26.31 | 58 / 26.31 | 58 / 26.31 | 58 / 26.31 | 81 / 36.74 | 69 / 31.30 |
| 10 | 81 / 36.74 | 81 / 36.74 | 81 / 36.74 | 91 / 41.28 | 124 / 56.25 | 100 / 45.36 |
| 12 | 115 / 52.16 | 115 / 52.16 | 115 / 52.16 | 140 / 63.50 | 185 / 83.91 | 142 / 64.41 |
| 14 | 165 / 74.84 | 165 / 74.84 | 165 / 74.84 | 190 / 86.18 | 250 / 113.40 | 206 / 93.44 |
| 16 | 210 / 95.25 | 220 / 99.79 | 190 / 86.18 | 234 / 106.14 | 315 / 142.88 | 250 / 113.40 |
| 18 | 253 / 114.76 | 280 / 127.01 | 250 / 113.40 | 305 / 138.35 | 414 / 187.83 | 320 / 145.15 |
| 20 | 315 / 142.88 | 325 / 147.42 | 315 / 142.88 | 375 / 170.10 | 515 / 233.60 | 400 / 181.44 |
| 22 | 370 / 167.83 | 370 / 167.83 | 370 / 167.83 | 435 / 197.31 | 640 / 290.30 | 465 / 210.92 |
| 24 | 490 / 222.26 | 490 / 222.26 | 475 / 215.46 | 550 / 249.48 | 800 / 362.87 | 580 / 263.08 |
Note: The above data is for reference only. Please refer to the ASME B16.5 standard for design and production.
ASME B16.5 Class 300 Flange Dimensions refer to the dimensional data specified in the ASME B16.5 standard for flanges with a pressure rating of Class 300.
These dimensions define the outer diameter, flange thickness, bolt hole quantity and size, and other critical parameters required for each NPS (Nominal Pipe Size).
Just like Class 150, the dimensions of Class 300 flanges remain exactly the same across all materials, including carbon steel, stainless steel, Duplex, super duplex, Inconel, Hastelloy, Monel, and copper-nickel alloys.
Different materials only affect the pressure–temperature ratings, not the geometric dimensions of the flange.
What is Class 300?
Class 300 is the second pressure rating level defined in ASME B16.5, offering significantly higher pressure capacity than Class 150.
It specifies the maximum allowable pressure a flange can withstand at various temperatures.
It does not mean the flange can only handle 300 psi—the allowable pressure varies with temperature.
For example (using ASTM A350 Gr. LF2 as a reference):
| Temperature (°C) | Max. Pressure (bar) |
| −29 to 38°C | 51.1 bar |
| 100°C | 46.6bar |
| 200°C | 43.8 bar |
Class 300 has roughly 2.5 times the pressure capacity of Class 150.
Class 300 Flange Characteristics
- Medium-pressure rating, one level above Class 150
- Larger and thicker dimensions with more bolts
- Higher pressure-handling capability for demanding service
- Fully standardized according to ASME B16.5
- Widely used in petrochemical, energy, offshore, and pressure-vessel systems
With standardized dimensions, high mechanical integrity, and excellent pressure–temperature performance, ASME B16.5 Class 300 flanges provide long-lasting safety and efficiency for critical piping applications. Whether you require Weld Neck, Slip-On, Blind, Socket Weld, Threaded, or Lap Joint flanges, we supply fully certified components that meet ASME and ANSI requirements. Contact us today for detailed Class 300 dimension charts, technical support, material recommendations, or customized flange solutions tailored to your project needs.
