DIN EN 1092-1
The European metric flange standard. Used worldwide on metric piping systems and on US projects with imported process equipment. PN 6 through PN 400 covers most pressure ratings encountered.
PN Ratings
PN stands for Pressure Nominal, expressed in bar (1 bar approximately equals 14.5 psi). Standard PN ratings are 6, 10, 16, 25, 40, 63, 100, 160, 250, 320, and 400. The PN rating is a designator, not a working pressure. Actual working pressure at temperature follows P-T tables in the standard, similar to ASME Class designators.
DN Sizes
DN stands for Diameter Nominal, expressed in millimeters. Common sizes run from DN 10 (3/8 inch nominal) through DN 4000 (158 inch nominal). DN does not equal outside diameter or inside diameter; it is a nominal designator that ties to specific dimensional tables.
Flange Types
- Type 01: plate flange (similar to slip-on without hub)
- Type 02: loose flange with weld neck collar (Type 32, 33, 34, 35, 36, 37)
- Type 05: blind flange
- Type 11: weld neck flange
- Type 12: hubbed slip-on
- Type 13: hubbed threaded
- Type 21: integral flange (forged with vessel or fitting)
Facing Designators
Type A (flat face), Type B1 (small raised face), Type B2 (raised face with serrations), Type C (tongue and groove), Type D (recess), Type E (spigot), Type F (small male and female), Type G (large male and female), Type H (tongue), Type I (groove). Standard pressure flanges use Type B1 raised face unless the project drawing specifies otherwise.
ASME vs DIN Compatibility
ASME and DIN flanges are not directly interchangeable. The outside diameter, bolt circle, bolt count, and bolt size all differ between standards. Adapter spools or transition flanges bridge the two systems where ASME process equipment connects to DIN piping. Quote the project standard explicitly and check the mating component drawing before ordering.