That seems like a hard job to do. Its like comparing bananas with peaches. Question is if you should qualify 1 system per 2 standards.
For B31.3 youll need ASTM material, for EN 13480 youre likely to EN materials. You need to choose one, so how can you then analyze two systems with one material, while each code requires its own materials? You cant.
There's an alternative, which I wouldnt suggest, but the the option would be to use ASTM materials in an EN 13480 piping system. Assuming PED 97/23/EC applies, you can make PMA's for the materials.
Furthermore, in AutoPIPE, there's an option to set the piping code to EN 13480. Im not sure what "general modle options" does in terms of pipe stress analysis.