Tips and Notes

Confusion with CLASS designations between valves and flanges

Flanges and Valves are classified by CLASS and most people refer to a flange or valve as being in classes 600, 800, 1500, etc.
That's not entirely correct. The term “pound or pressure class” should not appear in the description. The correct term is “class,” which refers to the temperature and pressure limits for flanges and valves, as specified in B16.5 and B16.34, respectively.

According to API 602, “Class 800 or 1500 is not an official class designation, but an intermediate class number that is widely used for compact valves with socket weld and threaded ends.”