DIMENSIONS CHART FOR NONMETALLIC FLAT GASKETS FOR CLASS 125 CAST IRON FLANGES


Nonmetallic flat ring and full face gasket dimensions for ASME/ANSI B16.1 Class 125 cast iron pipe flanges and flanged fittings per ASME B16.21.


Flat Ring Gasket

Flat Ring Gasket Dimensions for Class 125 Cast Iron Pipe Flanges (inches)
NPS Gasket ID Gasket OD
1 1.31 2.62
1 1/4 1.66 3.00
1 1/2 1.91 3.38
2 2.38 4.12
2 1/2 2.88 4.88
3 3.50 5.38
3 1/2 4.00 6.38
4 4.50 6.88
5 5.56 7.75
6 6.62 8.75
8 8.62 11.00
10 10.75 13.88
12 12.75 16.12
14 14.00 17.75
16 16.00 20.25
18 18.00 21.62
20 20.00 23.88
24 24.00 28.25
30 30.00 34.75
36 36.00 41.25
42 42.00 48.00
48 48.00 54.50

Notes:

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


Full Face Gasket

Full Face Gasket Dimensions for Class 125 Cast Iron Pipe Flanges (inches)
NPS ID OD Number
of
Holes
Hole
Diameter
Bolt
Circle
Dia.
1 1.31 4.25 4 0.62 3.12
1 1/4 1.66 4.62 4 0.62 3.50
1 1/2 1.91 5.00 4 0.62 3.88
2 2.38 6.00 4 0.75 4.75
2 1/2 2.88 7.00 4 0.75 5.50
3 3.50 7.50 4 0.75 6.00
3 1/2 4.00 8.50 8 0.75 7.00
4 4.50 9.00 8 0.75 7.50
5 5.56 10.00 8 0.88 8.50
6 6.62 11.00 8 0.88 9.50
8 8.62 13.50 8 0.88 11.75
10 10.75 16.00 12 1.00 14.25
12 12.75 19.00 12 1.00 17.00
14 14.00 21.00 12 1.12 18.75
16 16.00 23.50 16 1.12 21.25
18 18.00 25.00 16 1.25 22.75
20 20.00 27.50 20 1.25 25.00
24 24.00 32.00 20 1.38 29.50
30 30.00 38.75 28 1.38 36.00
36 36.00 46.00 32 1.62 42.75
42 42.00 53.00 36 1.62 49.50
48 48.00 59.50 44 1.62 56.00

Notes:

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


Reference:

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