PN vs ANSI Flanges: Differences, Applications and Compatibility
In industrial projects, choosing the right flanges is essential for the safety and optimal performance of piping systems. One of the most common confusions appears between PN (Pressure Nominal) standardized flanges and ANSI (American National Standards Institute) flanges.
Although both types serve the same purpose – connecting pipes, equipment and valves – the differences between them are significant and can directly affect compatibility and system performance.
What are PN flanges
PN flanges are standardized according to European norms, especially EN 1092-1, and are widely used across Europe and in many international projects.
PN (Pressure Nominal) indicates the nominal pressure expressed in bar.
Common examples:
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PN6
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PN10
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PN16
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PN25
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PN40
These values do not represent the exact working pressure, but rather a reference class depending on temperature and material.
What are ANSI flanges
ANSI flanges are defined according to American standards such as ASME B16.5 and ASME B16.47, and are commonly used in the USA, Middle East and international projects with American specifications.
In this case, pressure is expressed in classes.
Common examples:
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Class 150
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Class 300
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Class 600
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Class 900
Similar to PN, these classes do not directly represent the maximum pressure, but a combination of pressure, temperature and material.
Main differences between PN and ANSI flanges
1. Standardization system
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PN → European standard (EN 1092-1)
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ANSI → American standard (ASME B16.5)
2. Pressure designation
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PN → expressed in bar
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ANSI → expressed in classes
3. Dimensions and bolt holes
One of the most important differences is related to:
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bolt circle diameter
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number and diameter of bolt holes
These differences mean that, in most cases, PN and ANSI flanges are NOT compatible with each other.
4. Application area
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PN → mainly used in Europe
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ANSI → used in international and American-based projects
Approximate PN vs ANSI equivalence
Although there is no exact equivalence, in practice the following comparisons are commonly used:
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PN16 ≈ Class 150
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PN40 ≈ Class 300
IMPORTANT: these equivalences are only indicative. For critical applications, exact pressure, temperature and material parameters must be verified.
Are PN and ANSI flanges compatible?
In general, NO.
Even if some pressure values seem similar, differences in construction (hole positioning, diameters, thickness) make direct installation impossible without adaptations.
In certain situations, the following can be used:
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special adapters
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mechanical modifications
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custom engineering solutions
However, these solutions involve additional costs and require proper technical evaluation.
Typical applications
PN flanges
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water installations
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gas networks
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HVAC systems
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European industrial projects
ANSI flanges
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oil and gas industry
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international projects
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high-pressure systems
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offshore applications
How to choose the right flange type
Choosing between PN and ANSI should not be based only on price or availability.
It is important to consider:
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project specifications
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working pressure and temperature
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compatibility with other equipment
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end customer requirements
Conclusion
PN and ANSI flanges serve the same functional purpose, but differ in terms of standards, dimensions and pressure classification.
The correct choice depends on the project specifications and compatibility with the existing system. An incorrect selection can lead to technical issues, additional costs or even safety risks.
For a personalized offer for PN or ANSI flanges, we invite you to explore our product range and contact us.
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