DIMENSIONS CHART FOR NONMETALLIC FLAT GASKETS FOR CLASS 25 CAST IRON FLANGES

Nonmetallic flat ring and full face gasket dimensions for ASME/ANSI B16.1 Class 25 cast iron pipe flanges and flanged fittings per ASME B16.21.

Flat Ring Gasket Dimensions (inches)
NPS	Gasket ID	Gasket OD
4	4.50	6.88
5	5.56	7.88
6	6.62	8.88
8	8.62	11.12
10	10.75	13.62
12	12.75	16.38
14	14.00	18.00
16	16.00	20.50
18	18.00	22.00
20	20.00	24.25
24	24.00	28.75
30	30.00	35.12
36	36.00	41.88
42	42.00	48.50
48	48.00	55.00
54	54.00	61.75
60	60.00	68.12
72	72.00	81.38
84	84.00	94.25
96	96.00	107.25

Notes:

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

Full Face Gasket Dimensions (inches)
NPS	ID	OD	Number of Holes	Hole Diameter	Bolt Circle Dia.
4	4.50	9.00	8	0.75	7.50
55	5.56	10.00	8	0.75	8.50
66	6.62	11.00	8	0.75	9.50
88	8.62	13.50	8	0.75	11.75
100	10.75	16.00	12	0.75	14.25
122	12.75	19.00	12	0.75	17.00
144	14.00	21.00	12	0.88	18.75
166	16.00	23.50	16	0.88	21.25
188	18.00	25.00	16	0.88	22.75
200	20.00	27.50	20	0.88	25.00
244	24.00	32.00	20	0.88	29.50
300	30.00	38.75	28	1.00	36.00
366	36.00	46.00	32	1.00	42.75
422	42.00	53.00	36	1.12	49.50
488	48.00	59.50	44	1.12	56.00
544	54.00	66.25	44	1.12	62.75
600	60.00	73.00	52	1.25	69.25
722	72.00	86.50	60	1.25	82.50
844	84.00	99.75	64	1.38	95.50
966	96.00	113.25	68	1.38	108.50

Notes:

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