Dimensions of Class 300 Flat Ring Gaskets (up to 24 inches) as per ASME B16.21 to Suit ASME B16.5 Flanges.

Flat Ring Gasket Dimensions

  CLASS 300
Nominal
Pipe Size
(NPS)
Inside Diameter
(ID)
Outside Diameter
(OD)
inches mm inches mm
1/2 0.84 21 2.12 54
3/4 1.06 27 2.62 67
1 1.31 33 2.88 73
1 1/4 1.66 42 3.25 83
1 1/2 1.91 49 3.75 95
2 2.38 60 4.38 111
2 1/2 2.88 73 5.12 130
3 3.50 89 5.88 149
3 1/2 4.00 102 6.50 165
4 4.50 114 7.12 181
5 5.56 141 8.50 216
6 6.62 168 9.88 251
8 8.62 219 12.12 308
10 10.75 273 14.25 362
12 12.75 324 16.62 422
14 14.00 356 19.12 486
16 16.00 406 21.25 540
18 18.00 457 23.50 597
20 20.00 508 25.75 654
24 24.00 610 30.50 775