In the global industrial supply chain, pipelines often traverse borders, requiring components to meet disparate regional standards. For engineers and procurement managers, understanding the core differences between the three major international flange types—DIN flange, ANSI flange (now largely replaced by ASME), and JIS flange—is essential for seamless integration, safety, and inventory management.
This guide provides a focused comparison of these systems, covering their designation, pressure rating methods, and key compatibility concerns.
1. Standardization Body and Geographic Focus
| Standard System | Standardizing Body | Primary Geographic Use | Pressure Designation |
| DIN Flange | DIN (German Institute for Standardization) | Europe, often specified in Asia and the Middle East. | PN (Pressure Nominal) |
| ANSI/ASME Flange | ASME (American Society of Mechanical Engineers) | North America, commonly used globally in oil, gas, and power industries. | Class (e.g., Class 150, Class 300) |
| JIS Flange | JIS (Japanese Industrial Standards) | Japan, East Asia, and related manufacturing markets. | K (Kilogram-force) |
2. The Critical Difference: Pressure Rating Systems
The most significant distinction among the three standards is how they define the operational pressure of the industrial flanges:
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DIN (PN Rating): Uses Pressure Nominal (PN), representing the pressure in bar at room temperature (20℃）. For example, a PN16 DIN flange is rated for 16 bar.
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Related Guide: See Understanding DIN Flanges and PN Ratings (PN10–PN40) for a detailed breakdown of the PN system.
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ANSI/ASME (Class Rating): Uses Class ratings (e.g., Class 150, Class 300). These are dimensionally standardized and refer to a nominal pressure rating in psi, but the actual maximum working pressure is complexly determined by the pressure-temperature $(P/T)$ chart and the material of the ASME flange.
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JIS (K Rating): Uses a nominal pressure designated in kilograms-force per square centimeter ($\text{kgf/cm}^2$), often abbreviated as K (e.g., $10\text{K}$, $20\text{K}$). This system is generally simpler and more direct than the ASME system.
3. Compatibility and Interoperability Challenges
It is a common and dangerous misconception that flanges with numerically similar ratings are directly interchangeable across standards. While some overlap exists, DIN flange, ANSI flange, and JIS flange are generally not directly compatible due to key differences:
| Compatibility Factor | DIN Flange | ANSI/ASME Flange | JIS Flange |
| Bolt Circle Diameter (BCD) | Metric BCD | Imperial BCD | Metric BCD |
| Number of Bolts | Varies by size and PN rating | Standardized per Class/Size | Varies, often with a different bolt count than DIN/ASME |
| Flange Thickness | Varies based on PN rating | Varies based on Class rating | Varies based on K rating |
Critical Note: A JIS $10\text{K}$ flange should never be substituted directly for a Class 150 ASME flange or a PN16 DIN flange without consulting precise conversion tables and engineering specifications, as differences in bolt hole alignment or sealing surface can lead to leaks and system failure.
4. Conversion References: Bridging the Systems
For general referencing, the following table provides a rough correlation between common pressure ratings. However, these are only approximations and should not be used for final design or installation without detailed dimensional verification.
| DIN PN | ANSI/ASME Class (Approx.) | JIS K (Approx.) |
| PN6 | Class 150 (Lower End) | 5K |
| PN10 | Class 150 | 10K |
| PN16 | Class 150 | 10K / 20K |
| PN25 | Class 300 | 20K |
| PN40 | Class 300 (Upper End) | 30K |
Choosing between these standards also depends on the required flange types (like Weld Neck or Slip-On) and material requirements, which are also defined differently within each standard. For instance, an industrial flange used in a high-pressure environment must adhere strictly to the design codes of the prevailing system (e.g., ASME B16.5).
Deepen Your Flange Knowledge
Navigating these international standards is crucial for global projects. To further optimize your pipe fittings selection, explore these related resources:
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Flange Selection Guide: Learn the systematic approach to choosing the right flange based on pressure and connection type:
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Dimensional Data: Access charts for specific standard references during procurement and design:
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Core Flange Resource: Return to our complete overview of all flange types and industrial flanges:
Do you have specific dimensional conversion questions for your next project? Contact us for Technical Specifications.
