DIMENSIONS CHART FOR NONMETALLIC FLAT GASKETS FOR CLASS 125 CAST IRON FLANGES

Nonmetallic flat ring and full face gasket dimensions for ASME/ANSI B16.1 Class 125 cast iron pipe flanges and flanged fittings per ASME B16.21.

Flat Ring Gasket Dimensions for Class 125 Cast Iron Pipe Flanges (inches)
NPS	Gasket ID	Gasket OD
1	1.31	2.62
1 1/4	1.66	3.00
1 1/2	1.91	3.38
2	2.38	4.12
2 1/2	2.88	4.88
3	3.50	5.38
3 1/2	4.00	6.38
4	4.50	6.88
5	5.56	7.75
6	6.62	8.75
8	8.62	11.00
10	10.75	13.88
12	12.75	16.12
14	14.00	17.75
16	16.00	20.25
18	18.00	21.62
20	20.00	23.88
24	24.00	28.25
30	30.00	34.75
36	36.00	41.25
42	42.00	48.00
48	48.00	54.50

Notes:

NPS - Nominal Pipe Size, OD - Outer Diameter, ID - Inner Diameter

Full Face Gasket Dimensions for Class 125 Cast Iron Pipe Flanges (inches)
NPS	ID	OD	Number of Holes	Hole Diameter	Bolt Circle Dia.
1	1.31	4.25	4	0.62	3.12
1 1/4	1.66	4.62	4	0.62	3.50
1 1/2	1.91	5.00	4	0.62	3.88
2	2.38	6.00	4	0.75	4.75
2 1/2	2.88	7.00	4	0.75	5.50
3	3.50	7.50	4	0.75	6.00
3 1/2	4.00	8.50	8	0.75	7.00
4	4.50	9.00	8	0.75	7.50
5	5.56	10.00	8	0.88	8.50
6	6.62	11.00	8	0.88	9.50
8	8.62	13.50	8	0.88	11.75
10	10.75	16.00	12	1.00	14.25
12	12.75	19.00	12	1.00	17.00
14	14.00	21.00	12	1.12	18.75
16	16.00	23.50	16	1.12	21.25
18	18.00	25.00	16	1.25	22.75
20	20.00	27.50	20	1.25	25.00
24	24.00	32.00	20	1.38	29.50
30	30.00	38.75	28	1.38	36.00
36	36.00	46.00	32	1.62	42.75
42	42.00	53.00	36	1.62	49.50
48	48.00	59.50	44	1.62	56.00

Notes:

NPS - Nominal Pipe Size, OD - Gasket Outer Diameter, ID - Gasket Inner Diameter