Bolting Dimensions for API Flanges
| Nominal Size Inches | Gasket API Number | Number Of Studs | Stud Bolt Size Inches |
|---|---|---|---|
| 1-13/16 | BX151 | 8 | 7/8 X 5-1/2 |
| 2-1/16 | BX152 | 8 | 7/8 X 6 |
| 2-9/16 | BX153 | 8 | 1 X 6-3/4 |
| 3-1/16 | BX154 | 8 | 1-1/8 X 7-1/2 |
| 4-1/16 | BX155 | 8 | 1-3/8 X 9-1/4 |
| 5-1/8 | BX169 | 12 | 1-1/2 X 11-1/2 |
| 7-1/16 | BX156 | 16 | 1-1/2 X 12-3/4 |
| 9 | BX157 | 16 | 1-7/8 X 15-3/4 |
| 11 | BX158 | 20 | 2 X 19-1/4 |
| 13-5/8 | BX159 | 20 | 2-1/4 X 21-1/4 |
| 18-3/4 | BX164 | 20 | 3 X 26-3/4 |
