Flange and Bolt Dimensions - 150 lb to 2500 lb - ASME/ANSI B16.5
 

Diameters and bolt circles for standard ASME B16.5 flanges - 1/4 to 24 inches - 150 psi to 2500 psi

 

Nominal Pipe Size
NPS
(inches)

150 psi

Diameter of
Flange
(inches)

No.
of
Bolts

Diameter of
Bolts
(inches)

Bolt
Circle
(inches)

1/4

3-3/8

4

1/2

2-1/4

1/2

3-1/2

4

1/2

2-3/8

3/4

3-7/8

4

1/2

2-3/4

1

4-1/4

4

1/2

3-1/8

1-1/4

4-5/8

4

1/2

3-1/2

1-1/2

5

4

1/2

3-7/8

2

6

4

5/8

4-3/4

2-1/2

7

4

5/8

5-1/2

3

7-1/2

4

5/8

6

3-1/2

8-1/2

8

5/8

7

4

9

8

5/8

7-1/2

5

10

8

3/4

8-1/2

6

11

8

3/4

9-1/2

8

13-1/2

8

3/4

11-3/4

10

16

12

7/8

14-1/4

12

19

12

7/8

17

14

21

12

1

18-3/4

16

23-1/2

16

1

21-1/4

18

25

16

1-1/8

22-3/4

20

27-1/2

20

1-1/8

25

24

32

20

1-1/4

29-1/2

 

Nominal Pipe Size
NPS
(inches)

300 psi

Diameter of
Flange
(inches)

No.
of
Bolts

Diameter of
Bolts
(inches)

Bolt
Circle
(inches)

1/4

3-3/8

4

1/2

2-1/4

1/2

3-3/4

4

1/2

2-5/8

3/4

4-5/8

4

5/8

3-1/4

1

4-7/8

4

5/8

3-1/2

1-1/4

5-1/4

4

5/8

3-7/8

1-1/2

6-1/8

4

3/4

4-1/2

2

6-1/2

8

5/8

5

2-1/2

7-1/2

8

3/4

5-7/8

3

8-1/4

8

3/4

6-5/8

3-1/2

9

8

3/4

7-1/4

4

10

8

3/4

7-7/8

5

11

8

3/4

9-1/4

6

12-1/2

12

3/4

10-5/8

8

15

12

7/8

13

10

17-1/2

16

1

15-1/4

12

20-1/2

16

1-1/8

17-3/4

14

23

20

1-1/8

20-1/4

16

25-1/2

20

1-1/4

22-1/2

18

28

24

1-1/4

24-3/4

20

30-1/2

24

1-1/4

27

24

36

24

1-1/2

32

 

Nominal Pipe Size
NPS
(inches)

400 psi

Diameter of
Flange
(inches)

No.
of
Bolts

Diameter of
Bolts
(inches)

Bolt
Circle
(inches)

1/4

3-3/8

4

1/2

2-1/4

1/2

3-3/4

4