Intermediate Connection
Class 300 Nozzle Flanges
Intermediate connection flanges for Class 300 service
Class 300 Nozzle Flanges serve medium-pressure vessel and equipment connections where a size transition is needed between the nozzle and the piping. The Class 300 rating covers a wide range of process conditions, making these flanges one of the most frequently specified intermediate connection types in refining and chemical plants.
The flange face, whether raised face or ring-type joint, matches the standard B16.5 Class 300 dimensions for the nozzle (larger) size. This ensures compatibility with standard gaskets, bolting, and companion flanges already specified for the vessel nozzle. The reduced bore accommodates the smaller pipe schedule without altering the nozzle connection geometry.
Proper selection of a Class 300 nozzle flange requires verification that both the larger and smaller size ratings are adequate for the design conditions. The pressure-temperature rating of the flange is governed by the larger size class designation, but the reduced bore section must also be checked against minimum wall thickness requirements for the service pressure.
