JIS B2220 Japanese Flange Standards for Export to Japan

Why this matters

If you are bidding on equipment for Japanese plant operators, EPCs or shipyards, the default flange standard is JIS B2220. JIS flanges are not dimensionally compatible with EN 1092-1 or ASME B16.5, and even within JIS the 5K, 10K, 16K and 20K classes have distinct geometry. Specifying the wrong class will force a complete rework at site fit-up.

Scope comparison

Key characteristics

• Metric pressure designation: 10K means a nominal rating of 10 kgf/cm2, roughly 0.98 MPa or about 14.2 psi per K. So 10K is approximately 142 psi nominal and 20K approximately 284 psi nominal at ambient.
• Approximate equivalents: 10K is sometimes loosely compared to PN 10 / Class 150 and 20K to PN 20 / Class 150-to-300, but the actual flange OD, bolt circle and bolt count are JIS-specific. Do not rely on equivalence for fit.
• Face types: JIS commonly uses RF and FF; RTJ is less common.
• Material designations: Carbon steel weld-neck flanges are typically supplied to JIS G3201 SF440 or in ASTM A105 equivalent on export orders, when the buyer accepts.
• Smaller bolt count, smaller OD than ASME B16.5 of comparable nominal pressure for many sizes.

When to choose JIS B2220

• End user is in Japan: nearly always JIS B2220, especially in shipbuilding, refineries, power and water treatment.
• Marine and shipbuilding worldwide using Japanese-design vessels: JIS B2220 is often called up.
• Tie-in to existing JIS system: any expansion or modification to a Japanese-built plant.

We forge JIS B2220 flanges in the same shop as our forged flanges and non-standard forgings for ASME and EN markets, and we can offer matched-heat seamless butt-welding pipe fittings.

Procurement / spec checklist

1. State JIS B2220 explicitly along with type, nominal size, pressure class and face. Example: "WN flange, 100A, 20K, RF, JIS B2220, material SF440A".
2. Confirm pipe schedule (JIS uses Sch 10S, 20S, 40, 80 etc) and bore matches the flange neck.
3. Specify bolt thread (metric for true JIS) and gasket type compatible with the chosen face.
4. For export, agree the equivalent ASTM grade if the operator accepts it (e.g. SF440A vs A105N).
5. Provide MTR per EN 10204 3.1 unless the buyer requires JIS-style mill certificate.
6. Check that the flange marking includes the standard, class, size, material and heat number.

Need a JIS-spec line list quoted? Send your data sheet via our inquiry page; see also our certificates page.

Sources

• https://sunhyings.com/stainless-steel-flange/standards/jis-b2220/
• https://www.rishabhsteelindustries.com/jis-b2220-flanges-manufacturers-suppliers.html
• https://creativepiping.com/industrial-flanges/jis-b2220-flanges-manufacturer/
• https://baleng.com.au/flanges-japanese-standard/