Bolting Dimensions for API Flanges

20,000 lb. W.P.

Nominal Size Inches Gasket API Number Number Of Studs Stud Bolt Size Inches
1-13/16 BX151 8 1 X 7-1/2
2-1/16 BX152 8 1-1/8 X 8-1/4
2-9/16 BX153 8 1-1/4 X 9-1/4
3-1/16 BX154 8 1-3/8 X 10
4-1/16 BX155 8 1-3/4 X 12-1/4
7-1/16 BX156 16 2 X 17-1/2
9 BX157 16 2-1/2 X 22-1/2
11 BX158 16 2-3/4 X 23-3/4
13-5/8 BX159 20 3 X 30