What is the nominal pressure (PN) of a valve?

PN：

An identification code consisting of a combination of letters and numbers used for reference, related to the mechanical properties and dimensional characteristics of piping system components. It consists of the letters “PN” followed by a dimensionless number.

Note:

1. The numbers following the letters “PN” do not represent measured values and should not be used for calculation purposes, unless otherwise specified in the relevant standards.
2. The term “PN” has no meaning other than in relation to relevant standards for piping components.
3. The allowable pressure of a pipe fitting depends on its PN rating, material, design, and permissible operating temperature, among other factors. The allowable pressure is specified in the pressure-temperature rating tables of the relevant standards.
4. All pipe fittings with the same PN and DN ratings shall have the same mating dimensions as their corresponding flanges.