DIMENSIONS CHART FOR NONMETALLIC FLAT GASKETS FOR CLASS 300, 400, 600 AND 900 PIPE FLANGES

Flat ring nonmetallic gasket dimensions for Class 300, 400, 600 and 900 pipe flanges and flanged fittings per ASME B16.21.

Flat Ring Gasket Dimensions for Class 300, 400, 600 and 900 Pipe Flanges (inches)
NPS	Gasket ID	Gasket OD
NPS	Gasket ID	Class 300	Class 400	Class 600	Class 900
1/2	0.84	2.12	2.12	2.12	2.50
3/4	1.06	2.62	2.62	2.62	2.75
1	1.31	2.88	2.88	2.88	3.12
1 1/4	1.66	3.25	3.25	3.25	3.50
1 1/2	1.91	3.75	3.75	3.75	3.88
2	2.38	4.38	4.38	4.38	5.62
2 1/2	2.88	5.12	5.12	5.12	6.50
3	3.50	5.88	5.88	5.88	6.62
3 1/2	4.00	6.50	6.38	6.38	-
4	4.50	7.12	7.00	7.62	8.12
5	5.56	8.50	8.38	9.50	9.75
6	6.62	9.88	9.75	10.50	11.38
8	8.62	12.12	12.00	12.62	14.12
10	10.75	14.25	14.12	15.75	17.12
12	12.75	16.62	16.50	18.00	19.62
14	14.00	19.12	19.00	19.38	20.50
16	16.00	21.25	21.12	22.25	22.62
18	18.00	23.50	23.38	24.12	25.12
20	20.00	25.75	25.50	26.88	27.50
24	24.00	30.50	30.25	31.12	33.00

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