Cast Iron Flanges - ASME/ANSI Class 25

ASME/ANSI B16.1 - 1998 - Cast Iron Pipe Flanges and Flanged Fittings - Class 25 Flanges. Complete specifications including outside and inside diameters, bolt circles, numbers and diameters of bolts for pipe sizes from 4 inches to 96 inches.

Pipe Size (inches)	Outside Diameter (inches)	Number of Bolt Holes	Bolt Hole Diameter (inches)	Bolt Circle (inches)
4	9	8	3/4	7-1/2
5	10	8	3/4	8-1/2
6	11	8	3/4	9-1/2
8	13-1/2	8	3/4	11-3/4
10	16	12	3/4	14-1/4
12	19	12	3/4	17
14	21	12	7/8	18-3/4
16	23-1/2	16	7/8	21-1/4
18	25	16	7/8	22-3/4
20	27-1/2	20	7/8	25
24	32	20	7/8	29-1/2
30	38-3/4	28	1	36
36	46	32	1	42-3/4
42	53	36	1-1/8	49-1/2
48	59-1/2	44	1-1/8	56
54	66-1/4	44	1-1/8	62-3/4
60	73	52	1-1/4	69-1/4
72	86-1/2	60	1-1/4	82-1/2
84	99-3/4	64	1-3/8	95-1/2
96	113-1/4	68	1-3/8	108-1/2