DIN, ANSI and JIS flanges: what are the differences?
In industrial piping systems, choosing the right flange system is essential for proper maintenance and ensuring safety. Flanges must match perfectly with each other and with the piping system.
However, not all systems work the same way. The most commonly used international standards are DIN (EN), ANSI (ASME), and JIS. In this article, we explain what they mean, how they differ, and why this is essential when working with spades and blind flanges.
What are DIN, ANSI and JIS?
DIN, ANSI, and JIS are international standards that define how flanges are designed and used in piping systems.
They specify, among other things:
- flange dimensions
- bolt circle and bolt holes
- pressure ratings
- sealing faces
- material requirements and tolerances
Although they serve the same purpose, connecting pipes. They are not technically interchangeable.
DIN (EN 1092-1): European standard
DIN flanges, now largely defined in the EN 1092-1 standard, are the norm in Europe.
Characteristics:
- Metric system
- Pressure ratings: PN6, PN10, PN16, PN25, PN40 and higher
- More compact design compared to ANSI
- Widely used in water, HVAC, and chemical industries
Understanding the specifications:
A DN100 PN16 flange means:
- DN = nominal diameter (100 mm)
- PN16 = maximum pressure of 16 bar (depending on temperature and material)
DIN systems are highly standardized within Europe and therefore widely used in industrial installations.
ANSI / ASME: the international oil & gas standard
ANSI flanges (ASME B16.5) are dominant in the United States and globally in the oil and gas industry.
Characteristics:
- Inch-based system (e.g. 4”, 6”, 8”)
- Pressure classes: Class 150, 300, 600, 900, 1500, 2500
- Heavier and more robust flange constructions
- Widely used in high-pressure applications
Important difference:
The Class rating (e.g. Class 150) is not a direct pressure in bar or psi. The actual allowable pressure depends on temperature and material.
ANSI flanges are often used in international EPC projects and petrochemical installations.
JIS: Japanese industrial standard
JIS flanges are widely used in Japan and in Asian industrial applications, such as shipbuilding and OEM machinery.
Characteristics:
- Metric system with its own dimensions
- Pressure classes: 5K, 10K, 16K, 20K, 30K
- Often lighter than ANSI flanges
- Specific tolerances and dimensions
JIS systems are less common in Europe but often found in imported machinery and installations.
Why are they not interchangeable?
A common mistake is assuming that flanges with similar diameters (e.g. DN100 and 4”) will fit together. In practice, more factors are involved in ensuring a safe connection.
The main differences between systems lie in:
- bolt circle (PCD)
- number and diameter of bolt holes
- flange thickness
- sealing face
- pressure design
Due to these differences, even small deviations can make a safe seal impossible.
Which standard should I choose?
The choice depends entirely on the application:
- DIN / EN: European installations and utilities
- ANSI / ASME: oil & gas and international projects
- JIS: Asian machinery and shipbuilding
In many industrial projects, the standard is already defined in the design, meaning deviations are not possible without adapters or redesign.
Conclusion
DIN, ANSI, and JIS may seem similar, but they are technically completely different systems. Understanding these differences is essential for creating safe and reliable flange connections.
For applications such as blind flanges and spades, selecting the correct standard is not only a technical requirement but also a critical safety factor.
Questions?
Do you have any questions after reading this, or do you need advice when purchasing spades, blind flanges, or related products? Feel free to contact one of our experienced specialist