Dimensions of Class 250 RF Threaded Flanges as per ASME B16.1.

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

Cast Iron Flange Class 250

Flanges Blind Flanges Hubs Bolt Holes Bolting
Nom
Pipe
Size
Dia.
of
Flange
O
Min.
Thk.
of Flange
Q
Dia.
of
Raised
Face
W
Dia.
of Port
I
Wall
Thk.
V
Min.
Hub Dia.
X
Min.
Length thru'
Hub
Y
Min.
Length of
Threads
T
Dia.
of Bolt
Circle
Dia.
of Bolt
Holes
Num.
of
Bolts
Dia.
of
Bolts
Length of
Bolts
Length
of
Stud Bolts
1 125 17.5 68 25 ... 52 22 18 89 3/4 4 5/8 64 ...
1-1/4 135 19.0 78 32 ... 64 25 19 98 3/4 4 5/8 64 ...
1-1/2 155 20.6 91 38 ... 70 29 22 114 7/8 4 3/4 70 ...
2 165 22.2 106 51 ... 84 32 25 127 3/4 8 5/8 70 ...
2-1/2 190 25.4 125 64 ... 100 37 29 149 7/8 8 3/4 83 ...
3 210 28.6 144 76 ... 118 40 31 168 7/8 8 3/4 89 ...
3-1/2 230 30.2 160 89 ... 133 41 32 184 7/8 8 3/4 89 ...
4 255 31.8 176 102 ... 146 44 33 200 7/8 8 3/4 95 ...
5 280 34.9 211 127 ... 178 48 36 235 7/8 8 3/4 102 ...
6 320 36.5 246 152 ... 206 49 39 270 7/8 12 3/4 102 ...
8 380 41.3 303 203 ... 260 56 43 330 1-1/8 12 7/8 114 ...
10 445 47.6 357 254 23.8 321 60 49 387 1-1/4 16 1 131 ...
12 520 50.8 418 305 25.4 375 65 54 451 1-1/4 16 1-1/8 140 ...
14 585 54.0 481 337 28.6 413 68 57 514 1-3/8 20 1-1/8 152 ...
16 650 57.2 535 387 31.8 467 73 62 572 1-3/8 20 1-1/4 159 ...
18 710 60.3 592 432 34.9 ... ... ... 629 1-3/8 24 1-1/4 165 ...
20 775 63.5 649 483 38.1 ... ... ... 686 1-3/8 24 1-1/4 172 ...
24 915 69.8 770 584 41.3 ... ... ... 813 1-5/8 24 1-1/2 191 241
30 1090 76.2 945 737 50.8 ... ... ... 997 2 28 1-3/4 216 268
36 1270 85.7 1110 ... ... ... ... ... 1168 2-1/4 32 2 241 298
42 1450 93.7 1281 ... ... ... ... ... 1340 2-1/4 36 2 254 318
48 1650 101.6 1484 ... ... ... ... ... 1543 2-1/4 40 2 273 330

Imperial Dimensions: All Dimensions are in inches.

Flanges Blind Flanges Hubs Bolt Holes Bolting
Nom
Pipe
Size
Dia.
of
Flange
O
Min.
Thk.
of Flange
Q
Dia.
of
Raised
Face
W
Dia.
of Port
I
Wall
Thk.
V
Min.
Hub Dia.
X
Min.
Length thru'
Hub
Y
Min.
Length of
Threads
T
Dia.
of Bolt
Circle
Dia.
of Bolt
Holes
Num.
of
Bolts
Dia.
of
Bolts
Length of
Bolts
Length
of
Stud Bolts
1 4.88 0.69 2.69 1.00 ... 2.06 0.88 0.68 3.50 3/4 4 0.62 2.50 ...
1-1/4 5.25 0.75 3.06 1.25 ... 2.50 1.00 0.81 3.88 3/4 4 0.62 2.50 ...
1-1/2 6.12 0.81 3.56 1.50 ... 2.75 1.12 0.87 4.50 7/8 4 0.75 3.00 ...
2 6.50 0.88 4.19 2.00 ... 3.31 1.25 1.00 5.00 3/4 8 0.62 3.00 ...
2-1/2 7.50 1.00 4.94 2.50 ... 3.94 1.43 1.13 5.88 7/8 8 0.75 3.50 ...
3 8.25 1.12 5.69 3.00 ... 4.62 1.56 1.19 6.62 7/8 8 0.75 3.50 ...
3-1/2 9.00 1.19 6.31 3.50 ... 5.25 1.62 1.25 7.25 7/8 8 0.75 3.50 ...
4 10.00 1.25 6.94 4.00 ... 5.75 1.75 1.31 7.88 7/8 8 0.75 4.00 ...
5 11.00 1.38 8.31 5.00 ... 7.00 1.88 1.44 9.25 7/8 8 0.75 4.00 ...
6 12.50 1.44 9.69 6.00 ... 8.12 1.94 1.56 10.62 7/8 12 0.75 4.00 ...
8 15.00 1.62 11.94 8.00 ... 10.25 2.19 1.75 13.00 1 12 0.88 4.50 ...
10 17.50 1.88 14.06 10.00 0.94 12.62 2.38 1.94 15.25 1-1/8 16 1.00 5.50 ...
12 20.50 2.00 16.44 12.00 1.00 14.75 2.56 2.19 17.75 1-1/4 16 1.12 5.50 ...
14 23.00 2.12 18.94 13.25 1.12 16.25 2.69 2.25 20.25 1-1/4 20 1.12 6.00 ...
16 25.50 2.25 21.06 15.25 1.25 18.38 2.88 2.50 22.50 1-3/8 20 1.25 6.50 ...
18 28.00 2.38 23.31 17.00 1.38 ... ... ... 24.75 1-3/8 24 1.25 6.50 ...
20 30.50 2.50 25.56 19.00 1.50 ... ... ... 27.00 1-3/8 24 1.25 7.00 ...
24 36.00 2.75 30.31 23.00 1.62 ... ... ... 32.00 1-5/8 24 1.50 7.50 9.50
30 43.00 3.00 37.19 29.00 2.00 ... ... ... 39.25 2 28 1.75 8.50 10.50
36 50.00 3.38 43.69 ... ... ... ... ... 46.00 2-1/4 32 2.00 9.50 12.00
42 57.00 3.69 50.44 ... ... ... ... ... 52.75 2-1/4 36 2.00 10.00 12.50
48 65.00 4.00 58.44 ... ... ... ... ... 60.75 2-1/4 40 2.00 11.00 13.00