How can flanges be classified based on Pressure – temperature ratings?

Flanges are classified based on Pressure – temperature ratings as:

• A. 150 #
• B. 300 #
• C. 400 #
• D. 600 #
• E. 900 #
• F. 1500 #
• G. 2500 #

Pressure temperature rating carts in the standard ASME16.5 specify the non-shock working gauge pressure to which the flange can be subjected to at a particular temperature.