JIS flanges are manufactured to Japanese Industrial Standards. They are common on equipment and machinery made in Japan and used in various Asian markets. If you work with Japanese machinery or in projects with Japanese specifications, you will likely encounter them.
This guide explains the key features of JIS flanges, how they differ from other standards, and where they are used.
What Are JIS Flanges?
JIS stands for Japanese Industrial Standards. It is the national standards system of Japan. JIS B2220 is the main standard specifying dimensions and pressure ratings for steel pipe flanges.
Like other standards, JIS defines everything: outside diameter, bolt holes, thickness, and pressure ratings. This ensures flanges from different Japanese manufacturers will fit together.
Key Characteristics and How They Compare
JIS flanges have distinct features that set them apart from American (ASME) and European (DIN) standards.
| Feature | JIS Flange (JIS B2220) | ASME/ANSI Flange (ASME B16.5) | DIN Flange (EN 1092-1) |
| Measurement System | Metric (mm) | Imperial (inches) | Metric (mm) |
| Pressure Rating System | K (e.g., 5K, 10K, 16K, 20K, 30K, 40K) | Class (e.g., 150, 300, 600) | PN (Pressure Nominal) (e.g., PN6, PN10, PN16) |
| Bolt Holes | Through-holes for bolts and nuts. | Through-holes for stud bolts and nuts. | Often have tapped threads; bolts screw into the flange. |
| Common Face Type | Raised Face (RF) is typical. | Raised Face (RF) is typical. | Often used with a full-face gasket. |
| Primary Region of Use | Japan, Asia, and on Japanese-made equipment worldwide. | Americas, global oil & gas, many international projects. | Europe, the Middle East, and many international projects. |
Important Note on Pressure Ratings: The “K” rating (like 10K) is a pressure class, similar to “Class 150.” It does not mean 10 kg/cm². You must consult JIS pressure-temperature tables to find the actual maximum working pressure for your material and temperature.
Are JIS Flanges Interchangeable with Other Standards?
Generally, JIS flanges are not directly interchangeable with ASME or DIN flanges.
Even if the nominal pipe size is the same, the critical dimensions like the bolt circle diameter and bolt hole size are different. A JIS 10K flange will not bolt directly to an ANSI Class 150 or a DIN PN16 flange.
Trying to connect them will cause misalignment and leaks. If you need to connect a JIS flange to another standard, you must use a specially designed adapter spool or transition flange.
Common Types, Materials, and Applications
Flange Types:
JIS B2220 covers the same common types as other standards:
- Welding Neck Flange
- Slip-On Flange
- Blind Flange
- Threaded Flange
- Lap Joint Flange
Common Materials:
- Carbon Steel: Equivalent to S25C, S35C grades, similar to ASTM A105.
- Stainless Steel: SUS304, SUS316, similar to ASTM A182 F304/F316.
Typical Applications:
You will find JIS flanges primarily in two areas:
- Japanese-Made Equipment: On machinery, pumps, valves, and compressors manufactured in Japan for export.
- Industrial Plants in Asia: In chemical, water treatment, and manufacturing facilities within Japan and other Asian countries that follow Japanese engineering standards.
Frequently Asked Questions
Q: What does the “K” number (like 10K) actually mean?
A: The “K” is a pressure class designation from the older Japanese “JPI” standard. A 10K flange is roughly similar to an ANSI Class 150 flange in pressure capacity. A 20K flange is roughly similar to ANSI Class 300. Always check the pressure-temperature tables for exact ratings.
Q: How can I identify a JIS flange?
A: Look for markings stamped on the flange’s outer rim. It should show the standard (e.g., JIS B2220), the pressure rating (e.g., 10K), the material, and the size. The metric bolt sizes are also a clear indicator.
Q: My project uses Japanese equipment but is in the US. What should I do?
A: You have two main options. First, you can source the correct JIS flanges to match the equipment. Second, you can fabricate a short adapter spool that has a JIS flange on one end and an ASME flange on the other. This is a common solution.
Q: Is JIS B2220 still the current standard?
A: While JIS B2220 is well-known, Japan has been harmonizing many standards internationally. Some JIS flange dimensions may align with certain ISO (International Organization for Standardization) specifications. However, for compatibility with existing Japanese equipment, the JIS B2220 specifications remain the key reference.
Conclusion
JIS standard flanges are a distinct system used primarily with Japanese industrial equipment. Their metric “K” pressure ratings and unique dimensions mean they are not a direct substitute for ASME or DIN flanges. When working with Japanese machinery, you must identify and source the correct JIS-specified components to ensure a proper, leak-free connection.
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