When calculating circumferential stress parameter Nø/P/Rm from curves 3C and 4C, COMPRESS uses two different “?” values, one for curve 3C and other for curve 4C, for calculating circumferential membrane stresses in longitudinal and transverse axes.
However, per WRC-107, for calculating circumferential stress due to Radial load, only one ? value , corresponding to that calculated using K1 / K2 (as applicable) for Nø should be used.
Similarly, while calculating longitudinal stress due to radial load, the ? value should be calculated using K1 / K2 value ( as applicable) for Nx. This ? should be used for reading both the curves 3C and 4C for Nx/P/Rm.
Can somebody explain as to what is COMPRESS rationale behind using two different ? values for calculating one type of stress?
However, per WRC-107, for calculating circumferential stress due to Radial load, only one ? value , corresponding to that calculated using K1 / K2 (as applicable) for Nø should be used.
Similarly, while calculating longitudinal stress due to radial load, the ? value should be calculated using K1 / K2 value ( as applicable) for Nx. This ? should be used for reading both the curves 3C and 4C for Nx/P/Rm.
Can somebody explain as to what is COMPRESS rationale behind using two different ? values for calculating one type of stress?