My ANSI flange check shows several flanges have increased from class 600 to 900, what does this mean?
The ANSI flange check calculations are recommending increasing the Pressure rating from class 600 to 900 based on the combination of the design Pressure, axial force and bending moment across the flange, these calculations are shown in appendix O as based on ASME B31.7 nuclear piping code Para 1 704.5 (a). These flange checks are known to be conservative, and using the calculated effective Pressure in ASME VIII Div I appendix 2 for flange design, a more accurate design check can be completed.
