Standards Flange Dimensions

American ANSI B.16 Class 125 or 150 Dimensions

Nominal Pipe Size (in) No. of Holes Bolt Dia. (in.) Flanged Outside Dia. (in.) Bolt Circle Dia. (in.) Bolt Hole Dia. (in.)
2 4 5/8 6 4-3/4 3/4
2-1/2 4 5/8 7 5-1/2 3/4
3 4 5/8 7-1/2 6 3/4
1 4 1/2 4-1/4 3-1/8 5/8
1-1/4 4 1/2 4-5/8 3-1/2 5/8
4 8 5/8 9 7-1/2 3/4
6 8 3/4 11 9-1/2 7/8
5 8 3/4 10 8-1/2 7/8
1-1/2 4 1/2 5 3-7/8 5/8
3-1/2 8 5/8 8-1/2 7 3/4

American ANSI B.16 Class 250 or 300

Nominal Pipe Size (in) No. of Holes Bolt Dia. (in.) Flanged Outside Dia. (in.) Bolt Circle Dia. (in.) Bolt Hole Dia. (in.)
1-1/4 4 5/8 5-1/4 3-7/8 3/4
1-1/2 4 3/4 6-1/8 4-1/2 7/8
2 8 5/8 6-1/2 5 3/4
2-1/2 8 3/4 7-1/2 5-7/8 7/8
3 8 3/4 8-1/4 6-5/8 7/8
3-1/2 8 3/4 9 7-1/4 7/8
4 8 3/4 10 7-7/8 7/8
5 8 3/4 11 9-1/4 7/8
6 12 7/8 12-1/2 10-5/8 7/8
8 12 7/8 15 13 1

British Imperial Flanges BS 10

Nominal Pipe Size (in) No. of Holes Bolt Dia. (in.) Flanged Outside Dia. (in.) Bolt Circle Dia. (in.) Bolt Hole Dia. (in.)
1-1/4 4 1/2 4-3/4 3-7/16 5/8
1-1/2 4 1/2 5-1/4 3-7/8 5/8
2 4 5/8 6 4-1/2 3/4
2-1/2 4 5/8 6-1/2 5 3/4
3 4 5/8 7-1/4 5-3/4 3/4
3-1/2 4 5/8 8 6-1/2 3/4
4 4 5/8 8-1/2 7 3/4
5 8 5/8 10 8-1/4 3/4
6 8 5/8 11 9-1/4 3/4
7 8 5/8 12 10-1/4 3/4

Metric Flanges SABS 1123, BS 4504, DIN 2501

Nominal Pipe Size (mm) No. of Holes Bolt Size (mm) Flanged Outside Dia. (mm Bolt Circle Dia. (mm) Bolt Hole Dia. (mm)
50 4 M16 165 125 18
65 4 M16 185 145 18
80 8 M16 200 160 18
32 4 M16 140 100 18
40 4 M16 150 110 18
150 8 M20 285 240 22
175 8 M20 315 270 22
200 8 M20 340 295 22
100 8 M16 220 180 18
125 8 M16 250 210 18

DIN or PN 10 (10 Bar)

Nominal Pipe Size
NPS
(inches)		 Class 900 Pipe Flanges
Diameter of
Flange
(inches)		 No.
of
Bolts		 Diameter of
Bolts
(inches)		 Diameter of
Bolt Holes
(inches)		 Bolt
Circle
(inches)
1 5-7/8 4 7/8 1 4
1-1/4 6-1/4 4 7/8 1 4-3/8
1-1/2 7 4 1 1.12 4-7/8
1/2 4-3/4 4 3/4 0.88 3-1/4
3/4 5-1/8 4 3/4 0.88 3-1/2
2 8-1/2 8 7/8 1 6-1/2
5 13-3/4 8 1-1/4 1.38 11
6 15 12 1-1/8 1.25 12-1/2
8 18-1/2 12 1-3/8 1.5 15-1/2
10 21-1/2 16 1-3/8 1.5 18-1/2
2-1/2 9-5/8 8 1 1.12 7-1/2
3 9-1/2 8 7/8 1 7-1/2
4 11-1/2 8 1-1/8 1.25 9-1/4
12 24 20 1-3/8 1.5 21
14 25-1/4 20 1-1/2 1.62 22
16 27-3/4 20 1-5/8 1.75 24-1/2
18 31 20 1-7/8 2 27
20 33-3/4 20 2 2.12 29-1/2
24 41 20 2-1/2 2.62 35-1/2

DIN or PN 16 (16 Bar)

Nominal Pipe Size (mm) No. of Holes Bolt Size (mm) Flanged Outside Dia. (mm) Bolt Circle Dia. (mm) Bolt Hole Dia. (mm)
80 8 M16 200 160 18
100 8 M16 220 180 18
125 8 M16 250 210 18
32 4 M16 140 100 18
40 4 M16 150 110 18
175 8 M20 315 270 22
200 12 M20 340 295 22
50 4 M16 165 125 18
65 4 M16 185 145 18
150 8 M20 285 240 22

DIN or PN 25 (25 Bar)

Nominal Pipe Size (mm) No. of Holes Bolt Size (mm) Flanged Outside Dia. (mm) Bolt Circle Dia. (mm) Bolt Hole Dia. (mm)
65 8 M16 185 145 18
80 8 M16 200 160 18
100 8 M20 235 190 22
32 4 M16 140 100 18
150 8 M24 300 250 26
175 12 M24 330 280 26
200 12 M24 360 310 26
40 4 M16 150 110 18
50 4 M16 165 125 18
125 8 M24 270 220 26

DIN or PN 40 (40 Bar)

Nominal Pipe Size (mm) No. of Holes Bolt Size (mm) Flanged Outside Dia. (mm) Bolt Circle Dia. (mm) Bolt Hole Dia. (mm)
65 8 M16 185 145 18
80 8 M16 200 160 18
100 8 M20 235 190 22
32 4 M16 140 100 18
40 4 M16 150 110 18
50 4 M16 165 125 18
125 8 M24 270 220 26
150 8 M24 300 250 26
175 12 M27 250 295 30
200 12 M27 275 320 30

Japanese and Korean Flanges

Nominal Pipe Size (mm) No. of Holes Bolt Size (mm) Flanged Outside Dia. (mm) Bolt Circle Dia. (mm) Bolt Hole Dia. (mm)
10 4 M12 90 65 15
15 4 M12 95 70 15
20 4 M12 100 75 15
25 4 M16 125 90 19
32 4 M16 135 100 19
40 4 M16 140 105 19
50 4 M16 155 120 19
65 4 M16 175 140 19
80 8 M16 185 150 19
90 8 M16 195 160 19

JIS 20 & KOREAN 20 Kgf/cm2

Nominal Pipe Size (mm) No. of Holes Bolt Size (mm) Flanged Outside Dia. (mm) Bolt Circle Dia. (mm) Bolt Hole Dia. (mm)
10 4 M12 90 65 15
15 4 M12 95 70 15
20 4 M12 100 75 15
25 4 M16 125 90 19
32 4 M16 135 100 19
40 4 M16 140 105 19
50 8 M16 155 120 19
65 8 M16 175 140 19
80 8 M20 200 160 23
90 8 M20 210 170 23