Dear Mohammad,

I missed to notice the -ve sign on 75 Deg C temperature limit. I apologize for that. You are right L2-L3 represents the maximum displacement stress range.
But still I think you will be having a problem with restraint loads. ASME B31.3 319.3.1(b) makes it mandatory to compute the values for reactions as algebraic difference between the value at maximum(or min) temperature for the thermal ccle under analysis and the value at the temperature expected during installation. However I have the correct maximum ambient and minimum ambient for the site location, and cannot decide the true installation temperature, as I do not know when the piping is going to be fabricated and erected.