Dimensions of Class 125 FF Threaded Flanges as per ASME B16.1.

Metric Dimensions: All Dimensions are in mm unless noted otherwise in the table.

Cast Iron Flanges

Flanges Hub Blind Flanges Bolt Holes Bolting
Nom
Pipe
Size
Dia.
of
Flange
O
Min.
Thk.
of Flange
Q
Min.
Dia.
X
Min.
Length of
Hub and
Threads
Y
Dia.
of Port
I
Wall
Thk.
V
Dia.
of Bolt
Circle
Dia.
of Bolt
Holes
Num.
of
Bolts
Dia.
of
Bolts
Length of
Bolts
Length
of
Stud Bolts
1 110 11.1 49 18 25 9.6 79 5/8 4 1/2 45 ...
1-1/4 115 12.7 59 21 32 11.1 89 5/8 4 1/2 51 ...
1-1/2 125 14.3 65 22 38 12.7 98 5/8 4 1/2 51 ...
2 150 15.9 78 25 51 14.3 121 3/4 4 5/8 57 ...
2-1/2 180 17.5 91 29 64 15.9 140 3/4 4 5/8 64 ...
3 190 19.0 108 30 76 17.5 152 3/4 4 5/8 64 ...
3-1/2 215 20.6 122 32 89 19.0 178 3/4 8 5/8 70 ...
4 230 23.8 135 33 102 22.2 191 3/4 8 5/8 76 ...
5 255 23.8 164 37 127 22.2 216 7/8 8 3/4 76 ...
6 280 25.4 192 40 152 23.8 241 7/8 8 3/4 83 ...
8 345 28.6 246 45 203 27.0 299 7/8 8 3/4 89 ...
10 405 30.2 303 49 254 28.6 362 1 12 7/8 95 ...
12 485 31.8 357 56 305 20.6 432 1 12 7/8 95 ...
14 535 35.1 391 57 356 22.2 476 1-1/8 12 1 108 ...
16 595 36.5 445 64 406 25.4 540 1-1/8 16 1 114 ...
18 635 39.7 499 68 457 27.0 578 1-1/4 16 1-1/8 121 ...
20 700 42.9 553 73 508 28.6 635 1-1/4 20 1-1/8 127 ...
24 815 47.6 660 83 610 31.8 749 1-1/8 20 1-1/4 140 ...
30 985 54.0 ... ... 762 36.6 914 1-1/8 28 1-1/4 159 ...
36 1170 60.3 ... ... 914 41.3 1086 1-5/8 32 1-1/2 178 222
42 1345 66.7 ... ... 1066 46.0 1257 1-5/8 36 1-1/2 191 235
48 1510 69.9 ... ... 1219 50.8 1422 1-1/8 44 1-1/2 197 242
54 1685 76.2 ... ... ... ... 1594 2 44 1-1/4 216 267
60 1855 79.4 ... ... ... ... 1759 2 52 1-1/4 222 273
72 2195 88.9 ... ... ... ... 2096 2 60 1-1/4 241 292
84 2535 98.4 ... ... ... ... 2426 2-1/4 64 2 267 324
96 2875 108.0 ... ... ... ... 2756 2-1/2 68 2-1/4 292 356

Imperial Dimensions: All Dimensions are in inches.

Flanges Hub Blind Flanges Bolt Holes Bolting
Nom
Pipe
Size
Dia.
of
Flange
O
Min.
Thk.
of Flange
Q
Min.
Dia.
X
Min.
Length of
Hub and
Threads
Y
Dia.
of Port
I
Wall
Thk.
V
Dia.
of Bolt
Circle
Dia.
of Bolt
Holes
Num.
of
Bolts
Dia.
of
Bolts
Length of
Bolts
Length
of
Stud Bolts
1 4.25 0.44 1.94 0.69 1.00 0.38 3.12 5/8 4 1/2 2.00 ...
1-1/4 4.62 0.50 2.31 0.81 1.25 0.44 3.50 5/8 4 1/2 2.00 ...
1-1/2 5.00 0.56 2.56 0.88 1.50 0.50 3.88 5/8 4 1/2 2.00 ...
2 6.00 0.62 3.06 1.00 2.00 0.56 4.75 3/4 4 5/8 2.50 ...
2-1/2 7.00 0.69 3.56 1.12 2.50 0.63 5.50 3/4 4 5/8 2.50 ...
3 7.50 0.75 4.25 1.19 3.00 0.69 6.00 3/4 4 5/8 2.50 ...
3-1/2 8.50 0.81 4.81 1.25 3.50 0.75 7.00 3/4 8 5/8 3.00 ...
4 9.00 0.94 5.31 1.31 4.00 0.88 7.50 3/4 8 5/8 3.00 ...
5 10.00 0.94 6.44 1.44 5.00 0.88 8.50 7/8 8 3/4 3.00 ...
6 11.00 1.00 7.56 1.56 6.00 0.94 9.50 7/8 8 3/4 3.50 ...
8 13.50 1.12 9.69 1.75 8.00 1.06 11.75 7/8 8 3/4 3.50 ...
10 16.00 1.19 11.94 1.94 10.00 1.12 14.25 1 12 7/8 4.00 ...
12 19.00 1.25 14.06 2.19 12.00 0.81 17.00 1 12 7/8 4.00 ...
14 21.00 1.38 15.38 2.25 14.00 0.88 18.75 1-1/8 12 1 4.50 ...
16 23.50 1.44 17.50 2.50 16.00 1.00 21.25 1-1/8 16 1 4.50 ...
18 25.00 1.56 19.62 2.69 18.00 1.06 22.75 1-1/4 16 1-1/8 5.00 ...
20 27.50 1.69 21.75 2.88 20.00 1.12 25.00 1-1/4 20 1-1/8 5.00 ...
24 32.00 1.88 26.00 3.25 24.00 1.25 29.50 1-3/8 20 1-1/4 5.50 ...
30 38.75 2.12 ... ... 30.00 1.44 36.00 1-3/8 28 1-1/4 6.50  
36 46.00 2.38 ... ... 36.00 1.62 42.75 1-5/8 32 1-1/2 7.00 9.00
42 53.00 2.62 ... ... 42.00 1.81 49.50 1-5/8 36 1-1/2 7.50 9.50
48 59.50 2.75 ... ... 48.00 2.00 56.00 1-5/8 44 1-1/2 8.00 9.50
54 66.25 3.00 ... ... ... ... 62.75 2 44 1-3/4 8.50 10.50
60 73.00 3.12 ... ... ... ... 69.25 2 52 1-3/4 9.00 11.00
72 86.50 3.50 ... ... ... ... 82.50 2 60 1-3/4 9.50 11.50
84 99.75 3.88 ... ... ... ... 95.50 2-1/4 64 2 10.50 13.00
96 113.25 4.25 ... ... ... ... 108.50 2-1/2 68 2-1/4 11.50 14.00

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