Piping Class Ratings - Classes and Pressure Numbers (PN)

Pressure numbers (PN) compared to flange class designations

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.

Note! The piping rating must be governed by the pressure-temperature rating of the weakest pressure containing item in the piping system.

Related Topics

  • Pressure Ratings - Pressure ratings of pipes and tubes and their fittings - carbon steel , stainless steel, plastic, copper and more
  • Codes and Standards - Piping codes and standards - ASME, ANSI, ASTM, AGA, API, AWWA, BS, ISO, DIN and more..

Related Documents

Key Words

  • en: flange classes pressure numbers pn
  • es: clases brida de presión números pn
  • de: Flansch Klassen Druck Zahlen pn

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