I'm Trying to make verification between my manual calculation of Sustained load stress and Caesar report but the the results not match , I use the code equation for Sustained load PD/4t+0.75iMA/Z
I take P as 1200 Kpa , D=114.3 mm , t=8.56 (4" sch 80) , i=1.49 @ elbow , MA = squrt(Mx2+my2+mz2) take the moment from caesar report for force and moment , z=96871 mm3
in caesar i consider all case corroded =false , code =b31.1
but I don't know whar wrong

Piping Code ?
I think not all pipingd codes rated the torsion moment same.

Sustained stress uses corroded cross section in stress calculations.

I make Manual calculation considering all case corroded ,but I note in caesar's report that SIF for Elbow is the the same as non cases corroded ???
the code is b31.1
so why caesar deal with pipe as corroded and elbow non corroded , and how to modify it to make it calculate the all system as corroded

Almost all Piping Codes state that the flexibility analysis (SIFs, and stiffness matrix) is to be performed using "nominal dimensions". Corrosion, if addressed, is removed from the Section Modulus before making the stress computation.