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What is DN?

DN stands for 'Diameter Nominale'.

"

DN15

 

6"

DN150

 

 

 

"

DN20

 

8"

DN200

 

 

Put simply, it is a rough translation of mm from imperial sizes, assuming that an inch is 25mm.

1"

DN25

 

10"

DN250

 

 

 

1"

DN32

 

12"

DN300

 

 

We refer to a 12" flange as DN300, when in fact it is 304mm.

1"

DN40

 

14"

DN350

 

 

 

2"

DN50

 

15"

DN375

 

 

 

2"

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.

 

 

 

 

 

 

Table PCD

PCD (Pitch Circle Diameter) is the diameter of a circle that goes through each of the bolt holes.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

British Standard - BS10

Table D

 

 

 

 

 

Table E is the most popular for applications with water.

 

Table E

 

 

 

 

 

All dimensions are specified in inches.

 

Table F

 

 

 

 

 

 

 

Table G

 

 

 

 

 

 

 

Table H

 

 

 

 

 

 

 

Table J

 

 

 

 

 

 

 

Table K

 

 

 

 

 

 

American National Standards Institute (ANSI)

ANSI 125

 

 

 

 

 

Higher numbers denote higher pressures.

 

ANSI 150

 

 

 

 

 

Sometimes people use the word 'Class' instead of ANSI. e.g. an ANSI 150 flange might be called a 'Class 150'

 

ANSI 300

 

 

 

 

 

All dimensions are specified in inches.

 

ANSI 600

 

 

 

 

 

 

 

ANSI 900

 

 

 

 

 

 

 

ANSI 1500

 

 

 

 

 

 

British Standard - BS4504

BS4504-6

PN6

 

 

 

 

Engineers use the prefix PN (Pressure Nominale). e.g. a BA4504-16 flange will commonly be referred to as a PN16

 

BS4504-10

PN10

 

 

 

 

Generally, a PN16 flange is designed to withstand pressures up to 16 bar.

 

BS4504-16

PN16

 

 

 

 

All dimensions are specified in mm.

 

BS4504-25

PN25

 

 

 

 

 

 

BS4504-40

PN40

 

 

 

 

 

 

BS4504-64

PN64

 

 

 

 

 

 

BS4504-100

PN100

 

 

 

 

 

SABS 1123

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SABS 1123-600

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SABS 1123-1000

 

 

 

 

 

 

 

SABS 1123-1600

 

 

 

 

 

 

 

SABS 1123-2500

 

 

 

 

 

 

 

SABS 1123-4000

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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