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ANSI 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

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

7/8

7-1/4

4

10

8

7/8

7-7/8

5

11

8

7/8

9-1/4

6

12-1/2

12

7/8

10-5/8

8

15

12

1

13

10

17-1/2

16

1-1/8

15-1/4

12

20-1/2

16

1-1/4

17-3/4

14

23

20

1-1/4

20-1/4

16

25-1/2

20

1-3/8

22-1/2

18

28

24

1-3/8

24-3/4

20

30-1/2

24

1-1/2

27

24

36

24

1-3/4

32

 

Nominal Pipe Size
NPS
(inches)

600 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

7/8

7-1/4

4

10-3/4

8

7/8

8-1/2

5

13

8

1

10-1/2

6

14

12

1

11-1/2

8

16-1/2

12

1-1/8

13-3/4

10

20

16

1-1/4

17

12

22

20

1-1/4

19-1/4

14

23-3/4

20

1-3/8

20-3/4

16

27

20

1-1/2

23-3/4

18

29-1/4

20

1-5/8

25-3/4

20

32

24

1-5/8

28-1/2

24

37

24

1-7/8

33

 

Nominal Pipe Size
NPS
(inches)

900 psi

Diameter of
Flange
(inches)

No.
of
Bolts

Diameter of
Bolts
(inches)

Bolt
Circle
(inches)

1/2

4-3/4

4

3/4

3-1/4

3/4

5-1/8

4

3/4

3-1/2

1

5-7/8

4

7/8

4

1-1/4

6-1/4

4

7/8

4-3/8

1-1/2

7

4

1

4-7/8

2

8-1/2

8

7/8

6-1/2

2-1/2

9-5/8

8

1

7-1/2

3

9-1/2

8

7/8

7-1/2

4

11-1/2

8

1-1/8

9-1/4

5

13-3/4

8

1-1/4

11

6

15

12

1-1/8

12-1/2

8

18-1/2

12

1-3/8

15-1/2

10

21-1/2

16

1-3/8

18-1/2

12

24

20

1-3/8

21

14

25-1/4

20

1-1/2

22

16

27-3/4

20

1-5/8

24-1/2

18

31

20

1-7/8

27

20

33-3/4

20

2

29-1/2

24

41

20

2-1/2

35-1/2

 

Nominal Pipe Size
NPS
(inches)

1500 psi

Diameter of
Flange
(inches)

No.
of
Bolts

Diameter of
Bolts
(inches)

Bolt
Circle
(inches)

1/2

4-3/4

4

3/4

3-1/4

3/4

5-1/8

4

3/4

3-1/2

1

5-7/8

4

7/8

4

1-1/4

6-1/4

4

7/8

4-3/8

1-1/2

7

4

1

4-7/8

2

8-1/2

8

7/8

6-1/2

2-1/2

9-5/8

8

1

7-1/2

3

10-1/2

8

1-1/8

8

4

12-1/4

8

1-1/4

9-1/2

5

14-3/4

8

1-1/2

11-1/2

6

15-1/2

12

1-3/8

12-1/2

8

19

12

1-5/8

15-1/2

10

23

12

1-7/8

19

12

26-1/2

16

2

22-1/2

14

29-1/2

16

2-1/4

25

16

32-1/2

16

2-1/2

27-3/4

18

36

16

2-3/4

30-1/2

20

38-3/4

16

3

32-3/4

24

46

16

3-1/2

39

 

Nominal Pipe Size
NPS
(inches)

2500 psi

Diameter of
Flange
(inches)

No.
of
Bolts

Diameter of
Bolts
(inches)

Bolt
Circle
(inches)

1/2

5-1/4

4

3/4

3-1/2

3/4

5-1/2

4

3/4

3-3/4

1

6-1/4

4

7/8

4-1/4

1-1/4

7-1/4

4

1

5-1/8

1-1/2

8

4

1-1/8

5-3/4

2

9-1/4

8

1

6-3/4

2-1/2

10-1/2

8

1-1/8

7-3/4

3

12

8

1-1/4

9

4

14

8

1-1/2

10-3/4

5

16-1/2

8

1-3/4

12-3/4

6

19

8

2

14-1/2

8

21-3/4

12

2

17-1/4

10

26-1/2

12

2-1/2

21-1/4

12

30

12

2-3/4

24-3/8

 

What is DN?
DN stands for 'Diameter Nominale'.
Put simply, it is a rough translation of mm from imperial sizes, assuming that an inch is 25mm.
We refer to a 12" flange as DN300, when in fact it is 304mm.
½"
DN15
 
6"
DN150
¾"
DN20
 
8"
DN200
1"
DN25
 
10"
DN250
1¼"
DN32
 
12"
DN300
1½"
DN40
 
14"
DN350
2"
DN50
 
15"
DN375
2½"
DN65
 
16"
DN400
3"
DN80
 
18"
DN450
4"
DN100
 
20"
DN500
5"
DN125
 
24"
DN600
 
What is the PCD?
The PCD of a flange is one of the critical dimensions.
PCD (Pitch Circle Diameter) is the diameter of a circle that goes through each of the bolt holes.
 There are several standards for flanges, and we deal with four of them;
 
British Standard - BS10
Table D
Table E
Table F
Table G
Table H
Table J
Table K
 
Table E is the most popular for applications with water.
All dimensions are specified in inches.
 
Australian Standard - AS2129
Table C
Table D
Table E
Table F
Table G
Table H
Table J
 
These flanges are equivalent to the BS10 flanges, except that all dimensions are specified in mm.
In some sizes, bolt holes are slightly larger to give better clearance.
 
American National Standards Institute (ANSI)
ANSI 125
ANSI 150
ANSI 300
ANSI 600
ANSI 900
ANSI 1500
 
Higher numbers denote higher pressures.
Sometimes people use the word 'Class' instead of ANSI. e.g. an ANSI 150 flange might be called a 'Class 150'
All dimensions are specified in inches.
 
British Standard - BS4504
BS4504-6
BS4504-10
BS4504-16
BS4504-25
BS4504-40
BS4504-64
BS4504-100
PN6
PN10
PN16
PN25
PN40
PN64
PN100
Engineers use the prefix PN (Pressure Nominale). e.g. a BA4504-16 flange will commonly be referred to as a PN16
Generally, a PN16 flange is designed to withstand pressures up to 16 bar.
All dimensions are specified in mm.
 

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