Piping Class Ratings - Classes and Pressure Numbers (PN)
Piping Class Ratings based on ASME B16.5 and corresponding PN (Pression Nominal*):
| Flange Class | 150 | 300 | 400 | 600 | 900 | 1500 | 2500 |
| Flange Pressure Nominal, PN | 20 | 50 | 68 | 100 | 150 | 250 | 420 |
* Pression Nominal is the French equivalent of Pressure Nominal
Pression Nominal is the rating designator followed by a designation number indicating the approximate pressure rating in bars.
- 1 bar = 1x105 Pa (N/m2) = 0.1 N/mm2 = 10,197 kp/m2 = 10.20 m H2O = 0.98692 atm = 14.5038 psi (lbf/in2)
PN ratings do not provide a proportional relationship between different PN numbers, whereas class numbers do. Class numbers are therefore recommended before PN ratings.
