Selecting pressure vessel flanges requires determining 4 parameters:

Nominal Diameter – Determined by the specified diameter. (DN)

2. Nominal Pressure - Determined by the design pressure (PN)

3. Sealing Surface Type - Determined by factors such as pressure and installation location (Flat, Vented, Groove).

4. Flange Material - Determined based on pressure class, pipe material, heat treatment requirements, and the allowable corrosion margin of the medium. Also, note that certain materials have thickness limitations.