I have a Clad pipe, 12 mm CS and 3 mm SS, there are and significant effect of Clad over the stiffner of pipe??? I can ignore the stiffner effect of clad???

I am modeling the pipe with CS, 12mm, corrosion 0mm and modified the pipe density for and equivalent density between CS and SS. Is that enought?? or is required to consider the clad on piping system???

Morning,

The cladding shouldn't be part of the stress analysis other than the 0mm corrosion allowance & weight, which you have already accounted for.

Instead you should consider the effect of the piping on the cladding - expansion.