Bolting Dimensions for API Flanges

2000 lb. W.P.

Nominal Size Inches Gasket API Number Number Of Studs Stud Bolt Size Inches
2-1/16 R23 8 5/8 X 4-1/2
2-9/16 R26 8 3/4 X 5
3-1/8 R31 8 3/4 X 5-1/4
4-1/16 R37 8 7/8 X 6
5-1/8 R41 8 1 X 6-3/4
7-1/16 R45 12 1 X 7
9 R49 12 1-1/8 X 8
11 R53 16 1-1/4 X 8-3/4
13-5/8 R57 20 1-1/4 X 9
16-3/4 R65 20 1-1/2 X 10-1/4
21-1/4 R73 24 1-5/8 X 11-3/4
26-3/4 BX167 20 1-3/4 X 13-3/4