Cast Iron Flanges - ASME/ANSI Class 125

ASME/ANSI B16.1 Cast Iron Pipe Flanges and Flanged Fittings - Class 125 Flanges specifications including outside and inside diameters, bolt circles, numbers and diameters of bolts.

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