Gasket dimensions for flat ring and full face applications

ASME B16.21 class 900

Nominal bore Flat ring and full face gasket Flat ring gasket Full face gasket Nominal bore
Inner diameter Outer diameter Outer diameter Bolt circle diameter Diameter of holes Number of bolt holes
Inches mm Inches mm Inches mm Inches mm Inches mm
1/2 27/32 21.4 2 1/2 63.5 4 3/4 120.7 3 1/4 82.6 7/8 22.2 4 1/2
3/4 1 1/16 27.0 2 3/4 69.9 5 1/8 130.2 3 1/2 88.9 7/8 22.2 4 3/4
1 1 5/16 33.3 3 1/8 79.4 5 7/8 149.2 4 101.6 1 25.4 4 1
1 1/4 1 21/32 42.1 3 1/2 88.9 6 1/4 158.8 4 3/8 111.1 1 25.4 4 1 1/4
1 1/2 1 29/32 48.4 3 7/8 98.4 7 177.8 4 7/8 123.8 1 1/8 28.6 4 1 1/2
2 2 3/8 60.3 5 5/8 142.9 8 1/2 215.9 6 1/2 165.1 1 25.4 8 2
2 1/2 2 7/8 73.0 6 1/2 165.1 9 5/8 244.5 7 1/2 190.5 1 1/8 28.6 8 2 1/2
3 3 1/2 88.9 6 5/8 168.3 9 1/2 241.3 7 1/2 190.5 1 25.4 8 3
4 54 1/2 114.3 8 1/8 206.4 11 1/2 292.1 9 1/4 235.0 1 1/4 31.8 8 4
5 5 9/16 141.3 9 3/4 247.7 13 3/4 349.3 11 279.4 1 3/8 34.9 8 5
6 6 5/8 168.3 11 3/8 288.9 15 381.0 12 1/2 317.5 1 1/4 31.8 12 6
8 8 5/8 219.1 14 1/8 358.8 18 1/2 469.9 15 1/2 393.7 1 1/2 38.1 12 8
10 10 3/4 273.1 17 1/8 435.0 21 1/2 546.1 18 1/2 469.9 1 1/2 38.1 16 10
12 12 3/4 323.9 19 5/8 498.5 24 609.6 21 533.4 1 1/2 38.1 20 12
14 14 355.6 20 1/2 520.7 25 1/4 641.4 22 558.8 1 5/8 41.3 20 14
16 16 406.4 22 5/8 574.7 27 3/4 704.9 24 1/4 616.0 1 3/4 44.5 20 16
18 18 457.2 25 1/8 638.2 31 787.4 27 685.8 2 50.8 20 18
20 20 508.0 27 1/2 698.5 33 3/4 857.3 29 1/2 749.3 2 1/8 54.0 20 20
24 24 609.6 33 838.2 41 1041.4 35 1/2 901.7 2 5/8 66.7 20 24