| NPS | O | tf | X | Ah | Y (THD/SO) | Y (LAP) | Y (WN) | T | B (SO) | B (LAP) | B (WN) | r | Q | Bolt Circle Dia. | Bolt Qty | Bolt Hole Dia. | Bolt Dia. |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/2 | 95 | 14.2 | 38 | 21.3 | 22 | 22 | 52 | 16 | 22.4 | 22.9 | 3 | 23.6 | 66.5 | 4 | 5/8 | 1/2 | |
| 3/4 | 117 | 15.7 | 48 | 26.7 | 25 | 25 | 57 | 16 | 27.7 | 28.2 | 3 | 29 | 82.6 | 4 | 3/4 | 5/8 | |
| 1 | 124 | 17.5 | 54 | 33.5 | 27 | 27 | 62 | 18 | 34.5 | 35.1 | 3 | 35.8 | 88.9 | 4 | 3/4 | 5/8 | |
| 1 1/4 | 133 | 20.6 | 64 | 42.2 | 28 | 28 | 67 | 21 | 43.2 | 43.7 | 5 | 44.4 | 98.6 | 4 | 3/4 | 5/8 | |
| 1 1/2 | 155 | 22.4 | 70 | 48.3 | 32 | 32 | 70 | 22 | 49.5 | 50 | 6 | 50.5 | 114.3 | 4 | 7/8 | 3/4 | |
| 2 | 165 | 25.4 | 84 | 60.5 | 37 | 37 | 73 | 28 | 62 | 62.5 | 8 | 63.5 | 127.0 | 8 | 3/4 | 5/8 | |
| 2 1/2 | 190 | 28.4 | 100 | 73.2 | 41 | 41 | 79 | 32 | 74.7 | 75.4 | 8 | 76.2 | 149.4 | 8 | 7/8 | 3/4 | |
| 3 | 210 | 31.8 | 117 | 88.9 | 46 | 46 | 83 | 35 | 90.7 | 91.4 | 10 | 92.2 | 168.1 | 8 | 7/8 | 3/4 | |
| 3 1/2 | 229 | 35.1 | 133 | 101.6 | 49 | 49 | 86 | 40 | 103.4 | 104.1 | 10 | 104.9 | 184.2 | 8 | 1 | 7/8 | |
| 4 | 254 | 35.1 | 146 | 114.3 | 51 | 51 | 89 | 37 | 116.1 | 116.8 | 11 | 117.6 | 200.2 | 8 | 1 | 7/8 | |
| 5 | 279 | 38.1 | 178 | 141.2 | 54 | 54 | 102 | 43 | 143.8 | 144.5 | 11 | 144.5 | 235.0 | 8 | 1 | 7/8 | |
| 6 | 318 | 41.1 | 206 | 168.4 | 57 | 57 | 107 | 46 | 170.7 | 171.4 | 13 | 171.4 | 269.7 | 12 | 1 | 7/8 | |
| 8 | 381 | 47.8 | 260 | 219.2 | 68 | 68 | 117 | 51 | 221.5 | 222.2 | 13 | 222.2 | 330.2 | 12 | 1 1/8 | 1 | |
| 10 | 444 | 53.8 | 321 | 273 | 73 | 102 | 124 | 56 | 276.4 | 277.4 | 13 | 276.4 | 387.4 | 16 | 1 1/4 | 1 1/8 | |
| 12 | 521 | 57.2 | 375 | 323.8 | 79 | 108 | 137 | 60 | 327.2 | 328.2 | 13 | 328.7 | 450.8 | 16 | 1 3/8 | 1 1/4 | |
| 14 | 584 | 60.5 | 425 | 355.6 | 84 | 117 | 149 | 64 | 359.2 | 360.2 | 13 | 360.4 | 514.4 | 20 | 1 3/8 | 1 1/4 | |
| 16 | 648 | 63.5 | 483 | 406.4 | 94 | 127 | 152 | 68 | 410.5 | 411.2 | 13 | 411.2 | 571.5 | 20 | 1 1/2 | 1 3/8 | |
| 18 | 711 | 66.5 | 533 | 457.2 | 99 | 137 | 165 | 70 | 461.8 | 462.3 | 13 | 462 | 628.6 | 24 | 1 1/2 | 1 3/8 | |
| 20 | 775 | 69.8 | 587 | 508 | 104 | 146 | 168 | 73 | 513.1 | 514.4 | 13 | 512.8 | 685.8 | 24 | 1 5/8 | 1 1/2 | |
| 22 | 838 | 73.2 | 641 | 558.8 | 108 | 152 | 171 | 564.4 | 565.5 | 13 | 743.0 | 24 | 1 3/4 | 1 5/8 | |||
| 24 | 914 | 76.2 | 702 | 609.6 | 114 | 159 | 175 | 83 | 616 | 616 | 13 | 614.4 | 812.8 | 24 | 1 7/8 | 1 3/4 |
| NPS | O | tf | X | Ah | Y (THD/SO) | Y (LAP) | Y (WN) | T | B (SO) | B (LAP) | B (WN) | r | Q | Bolt Circle Dia. | Bolt Qty | Bolt Hole Dia. | Bolt Dia. |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/2 | 3.75 | 0.56 | 1.5 | 0.84 | 0.88 | 0.88 | 2.06 | 0.62 | 0.88 | 0.9 | 0.12 | 0.93 | 2.62 | 4 | 5/8 | 1/2 | |
| 3/4 | 4.62 | 0.62 | 1.88 | 1.05 | 1 | 1 | 2.25 | 0.62 | 1.09 | 1.11 | 0.12 | 1.14 | 3.25 | 4 | 3/4 | 5/8 | |
| 1 | 4.88 | 0.69 | 2.12 | 1.32 | 1.06 | 1.06 | 2.44 | 0.69 | 1.36 | 1.38 | 0.12 | 1.41 | 3.5 | 4 | 3/4 | 5/8 | |
| 1 1/4 | 5.25 | 0.81 | 2.5 | 1.66 | 1.12 | 1.12 | 2.62 | 0.81 | 1.7 | 1.72 | 0.19 | 1.75 | 3.88 | 4 | 3/4 | 5/8 | |
| 1 1/2 | 6.12 | 0.88 | 2.75 | 1.9 | 1.25 | 1.25 | 2.75 | 0.88 | 1.95 | 1.97 | 0.25 | 1.99 | 4.5 | 4 | 7/8 | 3/4 | |
| 2 | 6.5 | 1 | 3.31 | 2.38 | 1.44 | 1.44 | 2.88 | 1.12 | 2.44 | 2.46 | 0.31 | 2.5 | 5 | 8 | 3/4 | 5/8 | |
| 2 1/2 | 7.5 | 1.12 | 3.94 | 2.88 | 1.62 | 1.62 | 3.12 | 1.25 | 2.94 | 2.97 | 0.31 | 3 | 5.88 | 8 | 7/8 | 3/4 | |
| 3 | 8.25 | 1.25 | 4.62 | 3.5 | 1.81 | 1.81 | 3.25 | 1.38 | 3.57 | 3.6 | 0.38 | 3.63 | 6.62 | 8 | 7/8 | 3/4 | |
| 3 1/2 | 9 | 1.38 | 5.25 | 4 | 1.94 | 1.94 | 3.38 | 1.56 | 4.07 | 4.1 | 0.38 | 4.13 | 7.25 | 8 | 1 | 7/8 | |
| 4 | 10 | 1.38 | 5.75 | 4.5 | 2 | 2 | 3.5 | 1.44 | 4.57 | 4.6 | 0.44 | 4.63 | 7.88 | 8 | 1 | 7/8 | |
| 5 | 11 | 1.5 | 7 | 5.56 | 2.12 | 2.12 | 4 | 1.69 | 5.66 | 5.69 | 0.44 | 5.69 | 9.25 | 8 | 1 | 7/8 | |
| 6 | 12.5 | 1.62 | 8.12 | 6.63 | 2.25 | 2.25 | 4.06 | 1.81 | 6.72 | 6.75 | 0.5 | 6.75 | 10.62 | 12 | 1 | 7/8 | |
| 8 | 15 | 1.88 | 10.25 | 8.63 | 2.69 | 2.63 | 4.62 | 2 | 8.72 | 8.75 | 0.5 | 8.75 | 13 | 12 | 1 1/8 | 1 | |
| 10 | 17.5 | 2.12 | 12.62 | 10.75 | 2.88 | 4 | 4.88 | 2.19 | 10.88 | 10.92 | 0.5 | 10.88 | 15.25 | 16 | 1 1/4 | 1 1/8 | |
| 12 | 20.5 | 2.25 | 14.75 | 12.75 | 3.12 | 4.25 | 5.38 | 2.38 | 12.88 | 12.92 | 0.5 | 12.94 | 17.75 | 16 | 1 3/8 | 1 1/4 | |
| 14 | 23 | 2.38 | 16.75 | 14 | 3.31 | 4.62 | 5.88 | 2.5 | 14.14 | 14.18 | 0.5 | 14.19 | 20.25 | 20 | 1 3/8 | 1 1/4 | |
| 16 | 25.5 | 2.5 | 19 | 16 | 3.69 | 5 | 6 | 2.69 | 16.16 | 16.19 | 0.5 | 16.19 | 22.5 | 20 | 1 1/2 | 1 3/8 | |
| 18 | 28 | 2.62 | 21 | 18 | 3.88 | 5.38 | 6.5 | 2.75 | 18.18 | 18.2 | 0.5 | 18.19 | 24.75 | 24 | 1 1/2 | 1 3/8 | |
| 20 | 30.5 | 2.75 | 23.12 | 20 | 4 | 5.75 | 6.62 | 2.88 | 20.2 | 20.25 | 0.5 | 20.19 | 27 | 24 | 1 5/8 | 1 1/2 | |
| 22 | 33 | 2.88 | 25.25 | 22 | 4.25 | 6.25 | 6.75 | 22.22 | 22.25 | 0.5 | 29.25 | 24 | 1 3/4 | 1 5/8 | |||
| 24 | 36 | 3 | 27.62 | 24 | 4.5 | 6.25 | 6.88 | 3.25 | 24.25 | 24.25 | 0.5 | 24.19 | 32 | 24 | 1 7/8 | 1 3/4 |
| NPS | SO | THD | LAP | BL | WN |
|---|---|---|---|---|---|
| 1/2 | 2 / 0.91 | 2 / 0.91 | 2 / 0.91 | 2 / 0.91 | 3 / 1.36 |
| 3/4 | 3 / 1.36 | 3 / 1.36 | 3 / 1.36 | 3 / 1.36 | 3.5 / 1.59 |
| 1 | 3.5 / 1.59 | 3.5 / 1.59 | 3.5 / 1.59 | 4 / 1.81 | 4 / 1.81 |
| 1-1/4 | 4.5 / 2.04 | 4.5 / 2.04 | 4.5 / 2.04 | 6 / 2.72 | 4.5 / 2.04 |
| 1-1/2 | 6.5 / 2.95 | 6.5 / 2.95 | 6.5 / 2.95 | 8 / 3.63 | 8 / 3.63 |
| 2 | 8 / 3.63 | 8 / 3.63 | 8 / 3.63 | 10 / 4.54 | 10 / 4.54 |
| 2-1/2 | 12 / 5.44 | 12 / 5.44 | 11 / 4.99 | 15 / 6.80 | 14 / 6.35 |
| 3 | 15 / 6.80 | 15 / 6.80 | 14 / 6.35 | 20 / 9.07 | 18 / 8.16 |
| 3-1/2 | 21 / 9.53 | 21 / 9.53 | 20 / 9.07 | 29 / 13.15 | 26 / 11.79 |
| 4 | 26 / 11.79 | 26 / 11.79 | 25 / 11.34 | 33 / 14.97 | 35 / 15.88 |
| 5 | 31 / 14.06 | 31 / 14.06 | 29 / 13.15 | 44 / 19.96 | 43 / 19.50 |
| 6 | 44 / 19.96 | 44 / 19.96 | 42 / 19.05 | 61 / 27.67 | 57 / 25.85 |
| 8 | 67 / 30.39 | 67 / 30.39 | 64 / 29.03 | 100 / 45.36 | 89 / 40.37 |
| 10 | 91 / 41.28 | 91 / 41.28 | 110 / 49.90 | 155 / 70.31 | 125 / 56.70 |
| 12 | 130 / 58.97 | 130 / 58.97 | 152 / 68.95 | 226 / 102.51 | 175 / 79.38 |
| 14 | 191 / 86.64 | 191 / 86.64 | 210 / 95.25 | 310 / 140.61 | 233 / 105.69 |
| 16 | 253 / 114.76 | 253 / 114.76 | 280 / 127.01 | 398 / 180.53 | 295 / 133.81 |
| 18 | 310 / 140.61 | 310 / 140.61 | 345 / 156.49 | 502 / 227.73 | 360 / 163.29 |
| 20 | 378 / 171.46 | 378 / 171.46 | 420 / 190.51 | 621 / 281.71 | 445 / 201.85 |
| 22 | 405 / 183.70 | 405 / 183.70 | 455 / 206.39 | 720 / 326.59 | 505 / 229.06 |
| 24 | 539 / 244.50 | 539 / 244.50 | 615 / 278.96 | 936 / 424.10 | 640 / 290.30 |
Note: The above data is for reference only. Please refer to the ASME B16.5 standard for design and production.
ASME B16.5 Class 400 Flange Dimensions refer to the dimensional data specified in the ASME B16.5 standard for flanges with a Class 400 pressure rating.
These dimensions define how large and thick a Class 400 flange should be for each NPS (Nominal Pipe Size), including:
- Outer diameter (OD)
- Flange thickness (T)
- Number and size of bolt holes
- Bolt circle diameter (BCD)
- Facing type (RF or RTJ)
- Neck dimensions (for Weld Neck flanges)
All ASME B16.5 Class 400 flanges have standardized dimensions, regardless of material, including carbon steel, stainless steel, Inconel, Duplex, copper-nickel alloys, or other specialty metals.
Different materials only affect the pressure–temperature rating, not the geometric dimensions.
What is Class 400?
Class 400 is a pressure rating defined in ASME B16.5 for flanges.
It indicates the maximum allowable pressure the flange can handle at various temperatures.
For example, using ASTM A182 Gr. F304 flanges:
| Temperature (°C) | Max. Pressure (bar) |
| −29 to 38°C | 66.2 bar |
| 100°C | 54.5bar |
| 200°C | 49.3 bar |
Note: Class 400 does not mean the flange can only withstand 400 psi. It is a rating designation, not a fixed pressure value.
Characteristics of Class 400 Flanges
- Medium-to-high pressure rating suitable for high-pressure steam, gas, and chemical systems
- Larger and thicker than Class 150 / 300 flanges
- More and/or larger bolts with bigger bolt circles
- Fully standardized dimensions, globally accepted
- Widely used in petrochemical, offshore, energy, boiler, and refining industries
With standardized dimensions and certified materials, ASME B16.5 Class 400 flanges provide reliable performance and long-term safety in demanding industrial applications.
Whether you need Weld Neck, Slip-On, Blind, Socket Weld, Threaded, or Lap Joint flanges, we offer fully compliant, globally standardized components along with technical support, dimension charts, and pressure–temperature specifications for all NPS sizes.
