Recommended stud bolt dimensions for API 6BX Flanges to accommodate both R and RX gaskets from 2000 psi to 20000 psi rating flanges. Bolt dimensions are based on two nuts. If three nuts are required for bolt tensioning add one nut height to these dimensions.
Nut height may taken equal to bolt diameter.
Bolt dimensions for API 6BX 2000 psi flanges
| Flange Size (Inches) |
API Rating (psi) |
Bolt Dia (Inches) |
Length (Inches) |
Length (mm) |
| 26-3/4 | 2000 | 1.75 | 14.25 | 365 |
| 30 | 2000 | 1.625 | 14.5 | 370 |
Bolt dimensions for API 6BX 3000 psi flanges
| Flange Size (Inches) |
API Rating (psi) |
Bolt Dia (Inches) |
Length (Inches) |
Length (mm) |
| 26-3/4 | 3000 | 2 | 17.5 | 445 |
| 30 | 3000 | 1.875 | 17.75 | 455 |
Bolt dimensions for API 6BX 5000 psi flanges
| Flange Size (Inches) |
API Rating (psi) |
Bolt Dia (Inches) |
Length (Inches) |
Length (mm) |
| 13-5/8 | 5000 | 1.625 | 12.75 | 325 |
| 16-3/4 | 5000 | 1.875 | 14.75 | 375 |
| 18-3/4 | 5000 | 2 | 17.75 | 455 |
| 21-1/4 | 5000 | 2 | 19 | 485 |
Bolt dimensions for API 6BX 10000 psi flanges
| Flange Size (Inches) |
API Rating (psi) |
Bolt Dia (Inches) |
Length (Inches) |
Length (mm) |
| 1-13/16 | 10000 | 0.75 | 5.5 | 140 |
| 2-1/16 | 10000 | 0.75 | 5.5 | 140 |
| 2-9/16 | 10000 | 0.875 | 6.5 | 170 |
| 3-1/16 | 10000 | 1 | 7.25 | 185 |
| 4-1/16 | 10000 | 1.125 | 8.5 | 220 |
| 5-1/8 | 10000 | 1.125 | 9.25 | 235 |
| 7-1/16 | 10000 | 1.5 | 11.75 | 300 |
| 9 | 10000 | 1.5 | 13.5 | 345 |
| 11 | 10000 | 1.75 | 15.25 | 390 |
| 13-5/8 | 10000 | 1.875 | 17.75 | 455 |
| 16-3/4 | 10000 | 1.875 | 17.75 | 455 |
| 18-3/4 | 10000 | 2.25 | 22.75 | 580 |
| 21-1/4 | 10000 | 2.5 | 24.75 | 630 |
Bolt dimensions for API 6BX 15000 psi flanges
| Flange Size (Inches) |
API Rating (psi) |
Bolt Dia (Inches) |
Length (Inches) |
Length (mm) |
| 1-13/16 | 15000 | 0.875 | 6 | 155 |
| 2-1/16 | 15000 | 0.875 | 6.5 | 170 |
| 2-9/16 | 15000 | 1 | 7.25 | 185 |
| 3-1/16 | 15000 | 1.125 | 8 | 205 |
| 4-1/16 | 15000 | 1.375 | 9.75 | 250 |
| 5-1/8 | 15000 | 1.5 | 11.5 | 295 |
| 7-1/16 | 15000 | 1.5 | 13 | 335 |
| 9 | 15000 | 1.875 | 16 | 410 |
| 11 | 15000 | 2 | 19.5 | 500 |
| 13-5/8 | 15000 | 2.25 | 21.25 | 540 |
| 18-3/4 | 15000 | 3 | 26.75 | 680 |
Bolt dimensions for API 6BX 20000 psi flanges
| Flange Size (Inches) |
API Rating (psi) |
Bolt Dia (Inches) |
Length (Inches) |
Length (mm) |
| 1-13/16 | 20000 | 1 | 7.75 | 200 |
| 2-1/16 | 20000 | 1.125 | 8.5 | 220 |
| 2-9/16 | 20000 | 1.25 | 9.5 | 245 |
| 3-1/16 | 20000 | 1.375 | 10.25 | 265 |
| 4-1/16 | 20000 | 1.75 | 12.5 | 320 |
| 7-1/16 | 20000 | 2 | 17.75 | 455 |
| 9 | 20000 | 2.5 | 21.75 | 555 |
| 11 | 20000 | 2.75 | 23.75 | 605 |
| 13-5/8 | 20000 | 3 | 29.75 | 760 |