JIS marine flanges

JIS marine flanges are pipe flanges to the Japanese Industrial Standards JIS B 2220 series, widely fitted on ships built or repaired in Asian yards. The marine usage centers on the 5K and 10K pressure ratings (about 0.5 and 1.0 MPa), which set the bolt circle diameter, bolt count, and flange thickness for a given nominal bore. JIS flanges are not interchangeable with ASME or EN/DIN flanges of the same nominal size because the bolt patterns and outside diameters differ, so spares must match the installed standard. Common faces are flat face and raised face, with gasket selection following the service fluid.