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

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

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


Reference::

  • ASME B16.21-1992, Nonmetallic Flat Gaskets for Pipe Flanges