Orifice flange dimensions are covered in ASME B16.36. Orifice flanges are available from Class #300 to Class #2500. Class #300 flanges are available in threaded, slip-on, and weld neck end types. Whereas, Class# 600 and above flanges are available in only weld neck type end connection.
During an inspection of orifice flange, you should check for
- Outer & Inner Diameter of body
- Bolt Circle & Bolt hole Diameter
- Thickness of weld end
- Length of the Hub
- Straightness and alignment of the bolt hole
- Tap holes dimensions
Class 300 Orifice Flange Dimensions (Weld Neck Raised Face)
| Size in Inch | Size in mm | Outer Dia. | Flange Thick. | Hub OD | Weld Neck OD | Welding Neck Length | RF Dia. | RF Height | PCD | Orifice Hole dia | No of Bolts | Bolt Size UNC | RF Stud Length | Hole Size | ISO Stud Size | Weight in kg |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| A | B | C | D | E | F | G | H | I | ||||||||
| 1 | 25 | 125 | 36.6 | 54 | 33.4 | 81 | 50.8 | 2 | 88.9 | 6.4 | 4 | 5/8 | 125 | 3/4 | M16 | 4.5 |
| 1 1/2 | 40 | 155 | 36.6 | 70 | 48.3 | 84 | 73 | 2 | 114.3 | 6.4 | 4 | 3/4 | 135 | 7/8 | M20 | 6.5 |
| 2 | 50 | 165 | 36.6 | 84 | 60.3 | 84 | 92.1 | 2 | 127 | 6.4 | 8 | 5/8 | 125 | 3/4 | M16 | 7 |
| 2 1/2 | 65 | 190 | 36.6 | 100 | 73 | 87 | 104.8 | 2 | 149.2 | 6.4 | 8 | 3/4 | 135 | 7/8 | M20 | 7.5 |
| 3 | 80 | 210 | 36.6 | 117 | 88.9 | 87 | 127 | 2 | 168.3 | 9.5 | 8 | 3/4 | 135 | 7/8 | M20 | 9.4 |
| 4 | 100 | 255 | 36.6 | 146 | 114.3 | 90 | 157.2 | 2 | 200 | 12.7 | 8 | 3/4 | 135 | 7/8 | M20 | 13.2 |
| 6 | 150 | 320 | 36.6 | 206 | 168.3 | 98 | 215.9 | 2 | 269.9 | 12.7 | 12 | 3/4 | 135 | 7/8 | M20 | 14.6 |
| 8 | 200 | 380 | 39.7 | 260 | 219.1 | 110 | 269.9 | 2 | 330.2 | 12.7 | 12 | 7/8 | 145 | 1 | M24 | 30 |
| 10 | 250 | 445 | 46.1 | 321 | 273 | 116 | 323.8 | 2 | 387.3 | 12.7 | 16 | 1 | 165 | 1 1/8 | M27 | 41 |
| 12 | 300 | 520 | 49.3 | 375 | 323.8 | 129 | 381 | 2 | 450.8 | 12.7 | 16 | 1 1/8 | 180 | 1 1/4 | M30 | 62 |
| 14 | 350 | 585 | 52.4 | 425 | 355.6 | 141 | 412.8 | 2 | 514.4 | 12.7 | 20 | 1 1/8 | 185 | 1 1/4 | M30 | 84 |
| 16 | 400 | 650 | 55.6 | 483 | 406.4 | 144 | 469.9 | 2 | 571.5 | 12.7 | 20 | 1 1/4 | 195 | 1 3/8 | M33 | 111 |
| 18 | 450 | 710 | 58.8 | 533 | 457 | 157 | 533.4 | 2 | 628.6 | 12.7 | 24 | 1 1/4 | 205 | 1 3/8 | M33 | 138 |
| 20 | 500 | 775 | 62 | 587 | 508 | 160 | 584.2 | 2 | 685.8 | 12.7 | 24 | 1 1/4 | 215 | 1 3/8 | M33 | 171 |
| 24 | 600 | 915 | 68.3 | 702 | 610 | 167 | 692.2 | 2 | 812.8 | 12.7 | 24 | 1 1/2 | 240 | 1 5/8 | M39 | 247 |
Class 600 Orifice Flange Dimensions (Weld Neck Raised Face)
| Size in Inch | Size in mm | Outer Dia. | Flange Thick. | Hub OD | Weld Neck OD | Welding Neck Length | RF Dia. | RF Height | PCD | Orifice Hole dia | No of Bolts | Bolt Size UNC | RF Stud Length | Hole Size | ISO Stud Size | Weight in kg |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| A | B | C | D | E | F | G | H | I | ||||||||
| 1 | 25 | 125 | 36.6 | 54 | 33.5 | 81 | 50.8 | 7 | 88.9 | 6.4 | 4 | 5/8 | 125 | 3/4 | M16 | 5.5 |
| 1 1/2 | 40 | 155 | 36.6 | 70 | 48.3 | 84 | 73 | 7 | 114.3 | 6.4 | 4 | 3/4 | 135 | 7/8 | M20 | 7.8 |
| 2 | 50 | 165 | 36.6 | 84 | 60.3 | 84 | 92.1 | 7 | 127 | 6.4 | 8 | 5/8 | 125 | 3/4 | M16 | 8.3 |
| 2 1/2 | 65 | 190 | 36.6 | 100 | 73 | 87 | 104.8 | 7 | 149.2 | 6.4 | 8 | 3/4 | 135 | 7/8 | M20 | 10.8 |
| 3 | 80 | 210 | 36.6 | 117 | 88.9 | 87 | 127 | 7 | 168.3 | 9.5 | 8 | 3/4 | 135 | 7/8 | M20 | 12.6 |
| 4 | 100 | 275 | 38.1 | 152 | 114.3 | 102 | 157.2 | 7 | 215.9 | 12.7 | 8 | 7/8 | 150 | 1 | M24 | 19 |
| 6 | 150 | 355 | 47.7 | 222 | 168.3 | 117 | 215.9 | 7 | 292.1 | 12.7 | 12 | 1 | 180 | 1 1/8 | M27 | 37 |
| 8 | 200 | 420 | 55.6 | 273 | 219.1 | 133 | 269.9 | 7 | 349.2 | 12.7 | 12 | 1 1/8 | 195 | 1 1/4 | M30 | 53 |
| 10 | 250 | 510 | 63.5 | 343 | 273 | 152 | 323.8 | 7 | 431.8 | 12.7 | 16 | 1 1/4 | 220 | 1 3/8 | M33 | 86 |
| 12 | 300 | 560 | 66.7 | 400 | 323.8 | 156 | 381 | 7 | 489 | 12.7 | 20 | 1 1/4 | 230 | 1 3/8 | M33 | 102 |
| 14 | 350 | 605 | 69.9 | 432 | 355.6 | 165 | 412.8 | 7 | 527 | 12.7 | 20 | 1 3/8 | 240 | 1 1/2 | M36 | 150 |
| 16 | 400 | 685 | 76.2 | 495 | 406.4 | 178 | 469.9 | 7 | 603.2 | 12.7 | 20 | 1 1/2 | 260 | 1 5/8 | M39 | 190 |
| 18 | 450 | 745 | 82.6 | 546 | 457.2 | 184 | 533.4 | 7 | 654 | 12.7 | 20 | 1 5/8 | 280 | 1 3/4 | M42 | 240 |
| 20 | 500 | 815 | 88.9 | 610 | 508 | 190 | 584.2 | 7 | 723.9 | 12.7 | 24 | 1 5/8 | 300 | 1 3/4 | M42 | 295 |
| 24 | 600 | 940 | 101.6 | 718 | 609.6 | 203 | 692.2 | 7 | 838.2 | 12.7 | 24 | 1 7/8 | 335 | 2 | M48 | 365 |
Class 900 Orifice Flange Dimensions (Weld Neck Raised Face)
| Size in Inch | Size in mm | Outer Dia. | Flange Thick. | Hub OD | Weld Neck OD | Welding Neck Length | RF Dia. | RF Height | PCD | Orifice Hole dia | No of Bolts | Bolt Size UNC | RF Stud Length | Hole Size | ISO Stud Size | Weight in kg |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| A | B | C | D | E | F | G | H | I | ||||||||
| 1 | 25 | 150 | 38.1 | 52 | 33.5 | 83 | 50.8 | 7 | 101.6 | 6.4 | 4 | 7/8 | 150 | 1 | M24 | 5.4 |
| 1 1/2 | 40 | 180 | 38.1 | 70 | 48.3 | 89 | 73 | 7 | 123.8 | 6.4 | 4 | 1 | 160 | 1 1/8 | M27 | 7.8 |
| 2 | 50 | 215 | 38.1 | 105 | 60.3 | 102 | 92.1 | 7 | 165.1 | 6.4 | 8 | 7/8 | 150 | 1 | M30 | 11.5 |
| 2 1/2 | 65 | 245 | 41.3 | 124 | 73 | 105 | 104.8 | 7 | 190.5 | 6.4 | 8 | 1 | 165 | 1 1/8 | M27 | 15.8 |
| 3 | 80 | 240 | 38.1 | 127 | 88.9 | 102 | 127 | 7 | 190.5 | 9.5 | 8 | 7/8 | 150 | 1 | M24 | 22 |
| 4 | 100 | 290 | 44.5 | 159 | 114.3 | 114 | 157.2 | 7 | 235 | 12.7 | 8 | 1 1/8 | 180 | 1 1/4 | M30 | 22 |
| 6 | 150 | 380 | 55.6 | 235 | 168.3 | 140 | 215.9 | 7 | 317.5 | 12.7 | 12 | 1 1/8 | 195 | 1 1/4 | M30 | 70 |
| 8 | 200 | 470 | 63.5 | 298 | 219.1 | 162 | 269.9 | 7 | 393.7 | 12.7 | 12 | 1 3/8 | 230 | 1 1/2 | M36 | 119 |
| 10 | 250 | 545 | 69.9 | 368 | 273 | 184 | 323.8 | 7 | 469.9 | 12.7 | 16 | 1 3/8 | 240 | 1 1/2 | M36 | 204 |
| 12 | 300 | 610 | 79.4 | 419 | 323.8 | 200 | 381 | 7 | 533.4 | 12.7 | 20 | 1 3/8 | 260 | 1 1/2 | M36 | 303 |
| 14 | 350 | 640 | 85.8 | 451 | 355.6 | 213 | 412.8 | 7 | 558.8 | 12.7 | 20 | 1 1/2 | 280 | 1 5/8 | M39 | 400 |
| 16 | 400 | 705 | 88.9 | 508 | 406.4 | 216 | 469.9 | 7 | 616 | 12.7 | 20 | 1 5/8 | 290 | 1 3/4 | M42 | 510 |
| 18 | 450 | 785 | 101.9 | 565 | 457.2 | 229 | 533.4 | 7 | 685.8 | 12.7 | 20 | 1 7/8 | 330 | 2 | M48 | 738 |
| 20 | 500 | 855 | 108 | 622 | 508 | 248 | 584.2 | 7 | 749.3 | 12.7 | 20 | 2 | 355 | 2 1/8 | M52 | 932 |
| 24 | 600 | 1040 | 139.7 | 749 | 609.6 | 292 | 692.2 | 7 | 901.7 | 12.7 | 20 | 2 1/2 | 445 | 2 5/8 | M64 | 1511 |
Class 1500 Orifice Flange Dimensions (Weld Neck Raised Face)
| Size in Inch | Size in mm | Outer Dia. | Flange Thick. | Hub OD | Weld Neck OD | Welding Neck Length | RF Dia. | RF Height | PCD | Orifice Hole dia | No of Bolts | Bolt Size UNC | RF Stud Length | Hole Size | ISO Stud Size | Weight in kg |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| A | B | C | D | E | F | G | H | I | ||||||||
| 1 | 25 | 150 | 38.1 | 52 | 33.5 | 83 | 50.8 | 7 | 101.6 | 6.4 | 4 | 7/8 | 150 | 1 | M24 | 5.4 |
| 1 1/2 | 40 | 180 | 38.1 | 70 | 48.3 | 89 | 73 | 7 | 123.8 | 6.4 | 4 | 1 | 160 | 1 1/8 | M27 | 7.8 |
| 2 | 50 | 215 | 38.1 | 105 | 60.3 | 102 | 92.1 | 7 | 165.1 | 6.4 | 8 | 7/8 | 150 | 1 | M24 | 11.5 |
| 2 1/2 | 65 | 245 | 41.3 | 124 | 73 | 105 | 104.8 | 7 | 190.5 | 6.4 | 8 | 1 | 165 | 1 1/8 | M27 | 15.8 |
| 3 | 80 | 265 | 47.7 | 133 | 88.9 | 117 | 127 | 7 | 203.2 | 9.5 | 8 | 1 1/8 | 185 | 1 1/4 | M30 | 22 |
| 4 | 100 | 310 | 54 | 162 | 114.3 | 124 | 157.2 | 7 | 241.3 | 12.7 | 8 | 1 1/4 | 205 | 1 3/8 | M33 | 22 |
| 6 | 150 | 395 | 82.6 | 229 | 168.3 | 171 | 215.9 | 7 | 317.5 | 12.7 | 12 | 1 3/8 | 265 | 1 1/2 | M36 | 70 |
| 8 | 200 | 485 | 92.1 | 292 | 219.1 | 213 | 269.9 | 7 | 393.7 | 12.7 | 12 | 1 5/8 | 300 | 1 3/4 | M42 | 119 |
| 10 | 250 | 585 | 108 | 368 | 273 | 254 | 323.8 | 7 | 482.6 | 12.7 | 12 | 1 7/8 | 345 | 1 | M48 | 204 |
| 12 | 300 | 675 | 123.9 | 451 | 323.8 | 283 | 381 | 7 | 571.5 | 12.7 | 16 | 2 | 380 | 2 1/8 | M52 | 303 |
| 14 | 350 | 750 | 133.4 | 495 | 355.6 | 298 | 412.8 | 7 | 635 | 12.7 | 16 | 2 1/4 | 415 | 2 3/8 | M56 | 400 |
| 16 | 400 | 825 | 146.1 | 552 | 406.4 | 311 | 469.9 | 7 | 704.8 | 12.7 | 16 | 2 1/2 | 450 | 2 5/8 | M64 | 510 |
| 18 | 450 | 915 | 162 | 597 | 457.2 | 327 | 533.4 | 7 | 774.7 | 12.7 | 16 | 2 3/4 | 500 | 2 7/8 | M72 | 738 |
| 20 | 500 | 985 | 177.8 | 641 | 508 | 356 | 584.2 | 7 | 831.8 | 12.7 | 16 | 3 | 545 | 3 1/8 | M76 | 932 |
| 24 | 600 | 1170 | 203.2 | 762 | 609.6 | 406 | 692.2 | 7 | 990.6 | 12.7 | 16 | 3 1/2 | 620 | 3 5/8 | M90 | 1511 |
Class 2500 Orifice Flange Dimensions (Weld Neck Raised Face)
| Size in Inch | Size in mm | Outer Dia. | Flange Thick. | Hub OD | Weld Neck OD | Welding Neck Length | RF Dia. | RF Height | PCD | Orifice Hole dia | No of Bolts | Bolt Size UNC | RF Stud Length | Hole Size | ISO Stud Size | Weight in kg |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| A | B | C | D | E | F | G | H | I | ||||||||
| 1 | 25 | 160 | 38.1 | 57 | 33.5 | 92 | 50.8 | 7 | 108 | 6.4 | 4 | 7/8 | 150 | 1 | M24 | 6.5 |
| 1 1/2 | 40 | 205 | 44.5 | 79 | 48.3 | 111 | 73 | 7 | 146 | 6.4 | 4 | 1 1/8 | 180 | 1 1/4 | M30 | 13 |
| 2 | 50 | 235 | 50.8 | 95 | 60.3 | 127 | 92.1 | 7 | 171.4 | 6.4 | 8 | 1 | 185 | 1 1/8 | M27 | 19 |
| 2 1/2 | 65 | 265 | 57.2 | 114 | 73 | 143 | 104.8 | 7 | 196.8 | 6.4 | 8 | 1 1/8 | 205 | 1 1/4 | M30 | 24 |
| 3 | 80 | 305 | 66.7 | 133 | 88.9 | 168 | 127 | 7 | 228.6 | 9.5 | 8 | 1 1/4 | 230 | 1 3/8 | M33 | 43 |
| 4 | 100 | 355 | 76.2 | 165 | 114.3 | 190 | 157.2 | 7 | 273 | 12.7 | 8 | 1 1/2 | 260 | 1 5/8 | M39 | 66 |
| 6 | 150 | 485 | 108 | 235 | 168.3 | 273 | 215.9 | 7 | 368.3 | 12.7 | 8 | 2 | 350 | 2 1/8 | M52 | 172 |
| 8 | 200 | 550 | 127 | 305 | 219.1 | 318 | 269.9 | 7 | 438.2 | 12.7 | 12 | 2 | 385 | 2 1/8 | M52 | 261 |
| 10 | 250 | 675 | 165.1 | 375 | 273 | 419 | 323.8 | 7 | 539.8 | 12.7 | 12 | 2 1/2 | 490 | 2 5/8 | M64 | 485 |
| 12 | 300 | 760 | 184.2 | 441 | 323.8 | 464 | 381 | 7 | 619.1 | 12.7 | 12 | 2 3/4 | 540 | 2 7/8 | M72 | 730 |