Flange Pressure and Temperature Ratings, B16.5

American Society of Mechanical Engineers (ASME) has established standards for flanges, including pressuret temperature ratings.  ASME B16.5 - Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard.  ASME B16.5 is a standard that covers dimensions and tolerances for pipe flanges in a range of sizes.  The pressure-temperature ratings specified in ASME B16.5 are important for selecting flanges based on the expected operating conditions.

In ASME B16.5, flanges are categorized based on their pressure-temperature ratings, which are expressed in classes.  Each class has a specific pressure and temperature range.  The pressure-temperature ratings help ensure the compatibility of flanges with the intended service conditions.  The flange classes include 150, 300, 400, 600, 900, 1500, and 2500, where the numbers correspond to the nominal pressure in pounds per square inch (psi).

It's crucial to consult the specific version of the ASME B16.5 standard that is applicable to your situation, as standards may be updated over time.  Engineers and professionals in the field of piping and pressure vessels refer to these standards to ensure the proper selection of flanges for a given set of conditions.

Keep in mind that using flanges outside their specified pressure-temperature ratings can lead to safety issues and system failures.  Therefore, adherence to industry standards is essential for the proper design, installation, and operation of piping systems.