European and American flange standards use different rating systems. Projects that combine equipment from both regions need to keep them apart.
PN ratings
PN (pression nominale) is used in EN 1092-1 and the former DIN standards. The number is the nominal pressure in bar at reference temperature, for example PN10, PN16, PN25 and PN40.
Class ratings
ASME B16.5 and B16.47 use Classes 150, 300, 400, 600, 900, 1500 and 2500. A class is not a pressure value; the allowable working pressure depends on the material group and temperature, as tabulated in the standard.
Approximate correspondence
Class 150 is often compared with PN20, Class 300 with PN50 and Class 600 with PN100. This comparison only describes pressure capability. The dimensions are different: bolt circle, number of bolts and hole size do not match, so a PN flange will not bolt to a Class flange.
K ratings
Japanese (JIS B2220) and Korean (KS B1503) flanges use K ratings such as 5K, 10K and 20K, which again have their own dimensions.
What to check
When equipment and piping come from different suppliers, confirm the flange standard on both sides before ordering. Where a transition is unavoidable, a special drilled flange or an adaptor can be made to drawing.
About Hyupshin Flanges
Shandong Hyupshin Flanges Co., Ltd has manufactured forged steel flanges since 1988 and exports more than 90% of its production. Monthly output is about 2,000 tons, with a supply range of DN15 to DN3000. Orders are supplied with EN 10204 3.1 material certificates, and third-party inspection can be arranged. Certifications include ISO 9001, Korea KS, CE PED, UKCA, AD 2000, LRQA.
See the flange types and standards, or send your RFQ, drawing or item list. Minimum order is 1 ton or 100 pieces.