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Class 300 ANSI B16.5 Forged Flanges

Weld Neck Flange

Threaded Flange

Slip On Flange

Lap Joint Flange

Socket Weld Flange

Blind Flange

(Click any image above to enlarge it and lock it in place, then scroll to the bottom table for dimensions)
Nom. Pipe Size O T TJ R X #/Dia of Holesa Bolt Circle Dia B B2b B3 H L L2 L3c r C D Thr
½ 3.75 0.50 0.56 1.38 1.50 4-0.63 2.62 0.88 0.62 0.90 0.84 0.81 2.00 0.88 0.12 0.93 0.38 0.62
¾ 4.62 0.56 0.62 1.69 1.88 4-0.75 3.25 1.09 0.82 1.11 1.05 0.94 2.19 1.00 0.12 1.14 0.44 0.62
1 4.88 0.62 0.69 2.00 2.12 4-0.75 3.50 1.36 1.05 1.38 1.32 1.00 2.38 1.06 0.12 1.41 0.50 0.69
5.25 0.69 0.75 2.50 2.50 4-0.75 3.88 1.70 1.38 1.72 1.66 1.00 2.50 1.06 0.19 1.75 0.56 0.81
6.12 0.75 0.81 2.88 2.75 4-0.88 4.50 1.95 1.61 1.97 1.90 1.13 2.63 1.19 0.25 1.98 0.62 0.88
2 6.50 0.81 0.88 3.62 3.31 8-0.75 5.00 2.44 2.07 2.46 2.38 1.25 2.69 1.31 0.31 2.50 0.69 1.12
7.50 0.94 1.00 4.12 3.94 8-0.88 5.88 2.94 2.47 2.97 2.88 1.44 2.94 1.50 0.31 3.00 0.75 1.25
3 8.25 1.06 1.12 5.00 4.62 8-0.88 6.62 3.57 3.07 3.60 3.50 1.63 3.06 1.69 0.38 3.63 0.81 1.25
9.00 1.12 1.19 5.50 5.25 8-0.88 7.25 4.07 3.55 4.10 4.00 1.69 3.13 1.75 0.38 4.13 …. 1.44
4 10.00 1.19 1.25 6.19 5.75 8-0.88 7.88 4.57 4.03 4.60 4.50 1.82 3.32 1.88 0.44 4.63 …. 1.44
5 11.00 1.31 1.38 7.31 7.00 8-0.88 9.25 5.66 5.05 5.69 5.56 1.94 3.82 2.00 0.44 5.69 …. 1.69
6 12.50 1.38 1.44 8.50 8.12 12-0.88 10.62 6.72 6.07 6.75 6.63 2.00 3.82 2.06 0.50 6.75 …. 1.81
8 15.00 1.56 1.62 10.62 10.25 12-1.00 13.00 8.72 7.98 8.75 8.63 2.38 4.32 2.44 0.50 8.75 …. 2.00
10 17.50 1.81 1.88 12.75 12.62 16-1.12 15.25 10.88 10.02 10.92 10.75 2.56 4.56 3.75 0.50 10.88 …. 2.19
12 20.50 1.94 2.00 15.00 14.75 16-1.25 17.75 12.88 12.00 12.92 12.75 2.82 5.06 4.00 0.50 12.94 …. 2.38
14 23.00 2.06 2.12 16.25 16.75 20-1.25 20.25 14.14 13.25 14.18 14.00 2.94 5.56 4.38 0.50 14.19 …. 2.50
16 25.50 2.19 2.25 18.50 19.00 20-1.38 22.50 16.16 15.25 16.19 16.00 3.19 5.69 4.75 0.50 16.19 …. 2.69
18 28.00 2.31 2.38 21.00 21.00 24-1.38 24.75 18.18 17.25 18.20 18.00 3.44 6.19 5.12 0.50 18.19 …. 2.75
20 30.50 2.44 2.50 23.00 23.12 24-1.38 27.00 20.20 19.25 20.25 20.00 3.69 6.32 5.50 0.50 20.19 …. 2.88
22 33.00 2.57 2.63 25.25 25.25 24-1.63 29.25 22.22 21.25 22.25 22.00 3.93 6.43 5.75 0.50 22.19 …. 3.13
24 36.00 2.69 2.75 27.25 27.62 24-1.63 32.00 24.25 23.25 24.25 24.00 4.13 6.56 6.00 0.50 24.19 …. 3.25

Dimensions are in inches.

(a)- Bolt hole diameter 1/8 in. larger than bolt diameter.
(b)- Standard bore dimensions provided. See bore chart for other wall thicknesses.
(c)- This dimension is commonly associated with “true” lap joints. Industry standard is to make to the slip on length through the hub.

ANSI B16.5 Class 300 Forged Flange PDF (for printing).