Body flanges must transfer the weight and bending moment existing at the location of the flanges. These loads are not considered in the pressure-temperature ratings of ASME B16.5/B16.47 for standard flanges. COMPRESS will optionally apply the loads to standard flanges when the switch "Consider external loadings on flange MAWP rating" on the flange design dialog is checked.

The method COMPRESS uses to apply the external loads is to determine an "equivalent pressure" to account for the axial force and the bending moment acting on the flange face. The equivalent pressures are found using the method described in "Pressure Vessel Design Manual", Second Edition, by Dennis R. Moss, Appendix G, page 273. Click on the following link for an example of the equivalent pressure calculation: http://www.codeware.com/support/faq/1051.html