ASME B16.5-2020 · Reference Chart
ASME B16.5 Flange Dimensions
Complete dimensional reference for ASME B16.5 pipe flanges, Class 150 through 2500. Includes weld neck, slip on, blind, socket weld, and threaded flange dimensions.
ASME B16.5 Class 150 Flange Dimensions
All dimensions in millimeters (mm)
| NPS | OD | t (WN) | t (BL) | X (Hub) | Y (Length) | BCD | Bolts | RF Dia |
|---|---|---|---|---|---|---|---|---|
| 1/2" | 90 | 9.6 | 11.2 | 30 | 16 | 60.3 | 4×15.9 | 34.9 |
| 3/4" | 100 | 11.2 | 12.7 | 38 | 16 | 69.9 | 4×15.9 | 42.9 |
| 1" | 110 | 12.7 | 14.2 | 49 | 18 | 79.4 | 4×15.9 | 50.8 |
| 1-1/4" | 115 | 14.3 | 15.7 | 59 | 21 | 88.9 | 4×15.9 | 63.5 |
| 1-1/2" | 125 | 15.9 | 17.5 | 65 | 23 | 98.4 | 4×15.9 | 73 |
| 2" | 150 | 17.5 | 19.1 | 78 | 24 | 120.7 | 4×19.1 | 92.1 |
| 2-1/2" | 180 | 20.7 | 22.4 | 92 | 27 | 139.7 | 4×19.1 | 104.8 |
| 3" | 190 | 22.3 | 23.9 | 108 | 30 | 152.4 | 4×19.1 | 127 |
| 3-1/2" | 215 | 22.3 | 25.4 | 122 | 30 | 177.8 | 8×19.1 | 139.7 |
| 4" | 230 | 22.3 | 28.4 | 135 | 30 | 190.5 | 8×19.1 | 157.2 |
| 5" | 255 | 22.3 | 30.2 | 164 | 33 | 215.9 | 8×22.2 | 185.7 |
| 6" | 280 | 23.9 | 33.3 | 192 | 34 | 241.3 | 8×22.2 | 215.9 |
| 8" | 345 | 27 | 38.1 | 246 | 39 | 298.5 | 8×22.2 | 269.9 |
| 10" | 405 | 28.6 | 42.9 | 305 | 44 | 362 | 12×25.4 | 323.8 |
| 12" | 485 | 30.2 | 47.8 | 365 | 51 | 431.8 | 12×25.4 | 381 |
| 14" | 535 | 33.4 | 50.8 | 400 | 54 | 476.3 | 12×28.6 | 412.8 |
| 16" | 595 | 35 | 55.6 | 457 | 61 | 539.8 | 16×28.6 | 469.9 |
| 18" | 635 | 38.1 | 60.5 | 505 | 64 | 577.9 | 16×31.8 | 533.4 |
| 20" | 700 | 41.3 | 63.5 | 559 | 70 | 635 | 20×31.8 | 584.2 |
| 22" | 755 | 44.5 | 66.5 | 610 | 73 | 692.2 | 20×34.9 | 641.4 |
| 24" | 815 | 46.1 | 69.9 | 663 | 76 | 749.3 | 20×34.9 | 692.2 |
ASME B16.5 Class 300 Flange Dimensions
All dimensions in millimeters (mm)
| NPS | OD | t (WN) | t (BL) | X (Hub) | Y (Length) | BCD | Bolts | RF Dia |
|---|---|---|---|---|---|---|---|---|
| 1/2" | 95 | 14.3 | 14.2 | 38 | 21 | 66.7 | 4×15.9 | 34.9 |
| 3/4" | 115 | 15.9 | 15.7 | 48 | 24 | 82.6 | 4×15.9 | 42.9 |
| 1" | 125 | 17.5 | 17.5 | 54 | 27 | 88.9 | 4×19.1 | 50.8 |
| 1-1/4" | 135 | 20.7 | 19.1 | 64 | 29 | 98.4 | 4×19.1 | 63.5 |
| 1-1/2" | 155 | 22.3 | 20.6 | 70 | 30 | 114.3 | 4×19.1 | 73 |
| 2" | 165 | 25.4 | 22.4 | 84 | 33 | 127 | 8×19.1 | 92.1 |
| 2-1/2" | 190 | 28.6 | 25.4 | 100 | 36 | 149.2 | 8×22.2 | 104.8 |
| 3" | 210 | 31.8 | 28.4 | 117 | 40 | 168.3 | 8×22.2 | 127 |
| 3-1/2" | 230 | 35 | 30.2 | 133 | 43 | 184.2 | 8×22.2 | 139.7 |
| 4" | 255 | 31.8 | 31.8 | 146 | 43 | 200 | 8×22.2 | 157.2 |
| 5" | 280 | 35 | 35.1 | 178 | 48 | 235 | 8×22.2 | 185.7 |
| 6" | 320 | 37.3 | 38.1 | 206 | 48 | 269.9 | 12×22.2 | 215.9 |
| 8" | 380 | 41.3 | 44.5 | 260 | 52 | 330.2 | 12×25.4 | 269.9 |
| 10" | 445 | 47.7 | 50.8 | 321 | 60 | 387.4 | 16×28.6 | 323.8 |
| 12" | 520 | 50.8 | 55.6 | 375 | 66 | 450.8 | 16×31.8 | 381 |
| 14" | 585 | 54 | 60.5 | 425 | 72 | 514.4 | 20×31.8 | 412.8 |
| 16" | 650 | 57.2 | 63.5 | 483 | 78 | 571.5 | 20×34.9 | 469.9 |
| 18" | 710 | 60.4 | 66.7 | 533 | 84 | 628.6 | 24×34.9 | 533.4 |
| 20" | 775 | 63.5 | 69.9 | 587 | 90 | 685.8 | 24×41.3 | 584.2 |
| 22" | 840 | 66.7 | 73.2 | 641 | 96 | 749.3 | 24×41.3 | 641.4 |
| 24" | 915 | 69.9 | 76.2 | 702 | 102 | 812.8 | 24×41.3 | 692.2 |
ASME B16.5 Class 600 Flange Dimensions
All dimensions in millimeters (mm)
| NPS | OD | t (WN) | t (BL) | X (Hub) | Y (Length) | BCD | Bolts | RF Dia |
|---|---|---|---|---|---|---|---|---|
| 1/2" | 95 | 14.3 | 14.2 | 38 | 21 | 66.7 | 4×15.9 | 46.7 |
| 3/4" | 115 | 15.9 | 15.7 | 48 | 24 | 82.6 | 4×15.9 | 52.1 |
| 1" | 125 | 17.5 | 17.5 | 56 | 29 | 88.9 | 4×19.1 | 58.8 |
| 1-1/4" | 135 | 20.7 | 19.1 | 64 | 29 | 98.4 | 4×19.1 | 67.6 |
| 1-1/2" | 155 | 22.3 | 22.4 | 70 | 31 | 114.3 | 4×22.2 | 73.7 |
| 2" | 165 | 25.4 | 25.4 | 84 | 35 | 127 | 8×19.1 | 85.7 |
| 2-1/2" | 190 | 28.6 | 28.4 | 100 | 39 | 149.2 | 8×22.2 | 98.4 |
| 3" | 210 | 31.8 | 31.8 | 117 | 45 | 168.3 | 8×25.4 | 114.3 |
| 3-1/2" | 230 | 34.9 | 35.1 | 133 | 49 | 184.2 | 8×28.6 | 127 |
| 4" | 275 | 38.1 | 38.1 | 152 | 53 | 215.9 | 8×28.6 | 139.7 |
| 5" | 330 | 44.5 | 44.5 | 189 | 60 | 266.7 | 8×31.8 | 166.7 |
| 6" | 355 | 47.7 | 50.8 | 222 | 66 | 292.1 | 12×31.8 | 193.7 |
| 8" | 420 | 55.6 | 57.2 | 273 | 75 | 349.2 | 12×34.9 | 244.5 |
| 10" | 510 | 63.5 | 63.5 | 343 | 85 | 431.8 | 16×38.1 | 298.4 |
| 12" | 560 | 66.7 | 69.9 | 400 | 92 | 489 | 20×41.3 | 349.2 |
| 14" | 605 | 69.9 | 73.2 | 432 | 98 | 527 | 20×44.5 | 381 |
| 16" | 685 | 76.2 | 79.4 | 495 | 108 | 603.2 | 20×50.8 | 431.8 |
| 18" | 745 | 82.6 | 85.9 | 546 | 117 | 654 | 20×54.0 | 482.6 |
| 20" | 815 | 88.9 | 92.1 | 610 | 127 | 723.9 | 24×60.3 | 533.4 |
| 22" | 870 | 95.3 | 98.6 | 664 | 136 | 784.2 | 24×63.5 | 584.2 |
| 24" | 940 | 101.6 | 104.6 | 718 | 146 | 838.2 | 24×63.5 | 635 |
ASME B16.5 Class 900 Flange Dimensions
All dimensions in millimeters (mm)
| NPS | OD | t (WN) | t (BL) | X (Hub) | Y (Length) | BCD | Bolts | RF Dia |
|---|---|---|---|---|---|---|---|---|
| 1/2" | 120 | 22.3 | 22.4 | 38 | 32 | 82.6 | 4×22.2 | 46.7 |
| 3/4" | 130 | 25.4 | 25.4 | 44 | 35 | 88.9 | 4×22.2 | 52.1 |
| 1" | 150 | 28.6 | 28.4 | 52 | 39 | 101.6 | 4×25.4 | 58.8 |
| 1-1/4" | 160 | 28.6 | 28.4 | 64 | 41 | 111.1 | 4×25.4 | 67.6 |
| 1-1/2" | 180 | 31.8 | 31.8 | 70 | 44 | 123.8 | 4×28.6 | 73.7 |
| 2" | 215 | 38.1 | 38.1 | 105 | 57 | 165.1 | 8×25.4 | 85.7 |
| 2-1/2" | 245 | 41.3 | 41.1 | 124 | 64 | 190.5 | 8×28.6 | 98.4 |
| 3" | 240 | 38.1 | 38.1 | 127 | 54 | 190.5 | 8×28.6 | 114.3 |
| 4" | 290 | 44.5 | 44.5 | 159 | 70 | 235 | 8×31.8 | 139.7 |
| 5" | 350 | 50.8 | 50.8 | 190 | 79 | 279.4 | 8×34.9 | 166.7 |
| 6" | 380 | 55.6 | 55.6 | 222 | 86 | 317.5 | 8×34.9 | 193.7 |
| 8" | 470 | 63.5 | 63.5 | 273 | 102 | 393.7 | 12×38.1 | 244.5 |
| 10" | 545 | 69.9 | 69.9 | 343 | 116 | 469.9 | 16×41.3 | 298.4 |
| 12" | 610 | 79.4 | 79.4 | 400 | 130 | 533.4 | 20×44.5 | 349.2 |
| 14" | 640 | 85.8 | 85.9 | 451 | 142 | 558.8 | 20×47.6 | 381 |
| 16" | 705 | 92.1 | 92.1 | 495 | 152 | 616 | 20×54.0 | 431.8 |
| 18" | 785 | 101.6 | 101.6 | 546 | 165 | 685.8 | 20×60.3 | 482.6 |
| 20" | 855 | 108 | 108 | 610 | 178 | 749.3 | 20×63.5 | 533.4 |
| 22" | 925 | 117.5 | 117.5 | 660 | 191 | 806.5 | 20×69.9 | 584.2 |
| 24" | 1040 | 139.7 | 139.7 | 718 | 203 | 901.7 | 20×76.2 | 635 |
ASME B16.5 Class 1500 Flange Dimensions
All dimensions in millimeters (mm)
| NPS | OD | t (WN) | t (BL) | X (Hub) | Y (Length) | BCD | Bolts | RF Dia |
|---|---|---|---|---|---|---|---|---|
| 1/2" | 120 | 22.3 | 22.4 | 38 | 32 | 82.6 | 4×22.2 | 46.7 |
| 3/4" | 130 | 25.4 | 25.4 | 44 | 35 | 88.9 | 4×22.2 | 52.1 |
| 1" | 150 | 28.6 | 28.4 | 56 | 41 | 101.6 | 4×25.4 | 58.8 |
| 1-1/4" | 160 | 28.6 | 28.4 | 64 | 41 | 111.1 | 4×25.4 | 67.6 |
| 1-1/2" | 180 | 31.8 | 31.8 | 70 | 44 | 123.8 | 4×28.6 | 73.7 |
| 2" | 215 | 38.1 | 38.1 | 105 | 57 | 165.1 | 8×25.4 | 85.7 |
| 2-1/2" | 245 | 41.3 | 41.1 | 124 | 64 | 190.5 | 8×28.6 | 98.4 |
| 3" | 265 | 47.7 | 47.8 | 133 | 73 | 203.2 | 8×31.8 | 114.3 |
| 4" | 310 | 54 | 54.1 | 162 | 84 | 241.3 | 8×34.9 | 139.7 |
| 5" | 375 | 73.1 | 73.2 | 197 | 98 | 292.1 | 8×41.3 | 166.7 |
| 6" | 395 | 82.6 | 82.6 | 229 | 111 | 317.5 | 12×38.1 | 193.7 |
| 8" | 485 | 92.1 | 92.1 | 292 | 133 | 393.7 | 12×47.6 | 244.5 |
| 10" | 585 | 108 | 108 | 368 | 162 | 482.6 | 12×54.0 | 298.4 |
| 12" | 675 | 123.9 | 123.9 | 451 | 184 | 571.5 | 16×60.3 | 349.2 |
| 14" | 750 | 133.4 | 133.4 | 495 | 200 | 635 | 16×63.5 | 381 |
| 16" | 825 | 146.1 | 146.1 | 552 | 222 | 704.8 | 16×69.9 | 431.8 |
| 18" | 915 | 162 | 162 | 597 | 241 | 774.7 | 16×76.2 | 482.6 |
| 20" | 985 | 177.8 | 177.8 | 641 | 260 | 831.8 | 16×82.6 | 533.4 |
| 22" | 1060 | 196.9 | 196.9 | 692 | 276 | 898.5 | 16×88.9 | 584.2 |
| 24" | 1170 | 203.2 | 203.2 | 762 | 292 | 990.6 | 16×101.6 | 635 |
ASME B16.5 Class 2500 Flange Dimensions
All dimensions in millimeters (mm)
| NPS | OD | t (WN) | t (BL) | X (Hub) | Y (Length) | BCD | Bolts | RF Dia |
|---|---|---|---|---|---|---|---|---|
| 1/2" | 135 | 30.2 | 30.2 | 43 | 40 | 88.9 | 4×22.2 | 46.7 |
| 3/4" | 140 | 31.8 | 31.8 | 51 | 41 | 95.3 | 4×22.2 | 52.1 |
| 1" | 160 | 35.1 | 35.1 | 57 | 44 | 108 | 4×25.4 | 58.8 |
| 1-1/4" | 185 | 38.1 | 38.1 | 73 | 51 | 130.2 | 4×28.6 | 67.6 |
| 1-1/2" | 205 | 44.5 | 44.5 | 79 | 60 | 146.1 | 4×31.8 | 73.7 |
| 2" | 235 | 50.9 | 50.9 | 114 | 68 | 171.4 | 8×28.6 | 85.7 |
| 2-1/2" | 265 | 57.2 | 57.2 | 133 | 75 | 196.8 | 8×31.8 | 98.4 |
| 3" | 305 | 66.7 | 66.7 | 168 | 86 | 228.6 | 8×35.1 | 114.3 |
| 4" | 355 | 76.2 | 76.2 | 203 | 102 | 273 | 8×41.3 | 139.7 |
| 5" | 420 | 92.1 | 92.1 | 241 | 121 | 323.8 | 8×47.6 | 166.7 |
| 6" | 485 | 108 | 108 | 279 | 140 | 368.3 | 8×54.0 | 193.7 |
| 8" | 550 | 127 | 127 | 349 | 165 | 438.2 | 12×54.0 | 244.5 |
| 10" | 675 | 165.1 | 165.1 | 432 | 203 | 539.8 | 12×66.7 | 298.4 |
| 12" | 760 | 184.2 | 184.2 | 495 | 229 | 619.1 | 12×73.0 | 349.2 |
Important Notes
Dimension Definitions
- OD - Flange outside diameter
- t (WN) - Weld neck flange minimum ring thickness
- t (BL) - Blind flange minimum thickness
- X - Hub diameter at base (WN) or hub end (SO/SW/THD)
- Y - Length through hub (overall length)
- BCD - Bolt circle diameter
- RF Dia - Raised face diameter
General Notes
- Dimensions per ASME B16.5-2020
- Class 900 and 1500 do not include NPS 3-1/2
- Class 2500 covers NPS 1/2" through 12" only
- RF height: 1.6mm for Class 150/300, 6.4mm for Class 600-2500
- Bolt holes are not deducted from theoretical weights
- SO/SW/THD ring thickness equals WN thickness for Class 150/300
- For Class 600+, SO/SW/THD ring thickness is reduced by 3.2mm
ASME B16.5 Flange Types
Weld Neck (WN)
Tapered hub design for high-pressure applications. Butt-welded to pipe for maximum strength and fatigue resistance.
Slip On (SO)
Slips over pipe end, then fillet welded. Easier to align than weld neck, suitable for low to medium pressure.
Blind (BL)
Solid disk used to block off pipe ends or valves. Bolted between two flanges for isolation.
Socket Weld (SW)
Pipe inserts into socket, then fillet welded. Good for small bore, high-pressure applications.
Threaded (THD)
Screwed connection, no welding required. Used for low-pressure, non-critical services.
Lap Joint (LJ)
Used with stub ends. Freely rotates for easy bolt alignment, common in lined piping systems.