What is ANSI flange?
ANSI flanges today comply with the ASME B16.5 standard, although the term ANSI is still used colloquially.
This standard is common in:
- Export projects
- Oil and gas applications
- International OEM Solutions
Common pressure classes are:
- Class 150
- Class 300
- Class 600
- Class 900
- Class 1500
- Class 2500
The pressure class is specified as Class and is linked to the permissible pressure at different temperatures.

What is DIN flange?
DIN flanges are based on European standards, today most often according to EN 1092-1, although many still say DIN.
These are mainly used in Europe and in Swedish industrial environments.
Common pressure classes are:
- PN10
- PN16
- PN25
- PN40
- PN63
- PN100
- PN160
- PN250
- PN420§
Here, the pressure class is given as PN (Pressure Nominal).
Key difference: the dimensions
What is most critical is that the flanges have different:
- Outer diameter
- bolt circle
- Number of holes
- Hole diameter
- Sealing surface
This means that an ANSI flanged valve does not normally fit directly against a DIN counter flange.
For example, even if the dimension is DN50 or 2", the bolt pattern can be completely different.
Example
It is important to always check:
- dimension
- Pressure class
- Flange standard
- Length of construction
before ordering.
The table below shows a comparison between DN50 ANSI Class 150 and DIN PN16, which, despite similar dimensions, illustrates the differences between the respective standards.
|
Parameter
|
DIN PN16
|
ANSI CL150
|
|
Nominal Dimension (DN/inch)
|
DN50
|
2”
|
|
Number of bolt holes
|
4
|
4
|
|
Bolt hole diameter (mm)
|
18
|
19
|
|
Bolt Circle / Pitch Circle Diameter (mm)
|
125
|
121
|
|
Build length / Face-to-face (mm)
|
150
|
178
|
|
Outer diameter flange (OD, mm)
|
165
|
150
|
|
Pressure class
|
PN16
|
Class 150
|
When is which standard used?
ANSI
Common in:
- International projects
- Export Machinery
- Processing plants
- Energy and pipeline
DIN / EN
Common in:
- European Installations
- Swedish industry
- water and plumbing
- standardised process systems in Europe
Our advice
If you are unsure whether your existing installation is ANSI or DIN, we are happy to help you check the correct standard before ordering. This saves both time and unnecessary rebuilding.
ANSI flanged products for the entire piping system
In our wide range, we offer several product groups with ANSI flanged connections.
This includes, among other things:
This makes it possible to standardize the entire installation with the same flange standard and simplify both design, installation and future service.