JIS B2401 (Japanese O-Ring Standard)
Also known as: JIS O-ring · P-series O-ring · G-series O-ring · JIS B2401-1
JIS B2401 is the Japanese Industrial Standard for O-rings, defining P-series (piston/bore), G-series (groove face), S-series (straight pipe), and V-series (vacuum) in metric dimensions.
Technical Detail
JIS B2401 defines four O-ring series in metric (mm) dimensions: P-series (P3–P400): general-purpose piston/cylinder seals, cross-section 1.9–8.4 mm W depending on size. G-series (G25–G300): face-seal O-rings for grooved flanges, matching JIS B2404 flange groove dimensions. S-series: straight pipe thread seals. V-series: vacuum KF/ISO flanges. All JIS grooves and mating dimensions are specified in companion standards JIS B2406 (groove for cylinders) and JIS B2404 (groove for pipe flanges). JIS B2401 is dominant in Japanese-supplied equipment (pumps, valves, heat exchangers) widespread in Vietnamese petroleum, chemical, and power plants. When replacing O-rings on Japanese equipment, always verify series (P vs G) and size number — a P10 (9.8 mm ID) is very different from G10 (9.8 mm ID but different cross-section).
Reference Standards
- JIS B2401-1:2012
- JIS B2404
- JIS B2406
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