I endorse the views of some participant to use ASME B31.3 Piping Design Code for Chemical Plant Piping. Certainly I will not favour the use of B31.9 Code.
First of all, the operating temperature mentioned seems to be incorrect sice at the pressure of 1305 PSI the steam will have a saturation temperature of around 500 Deg C. Secondly the thickness selected i.e.10.97mm Sch 80 / XS is undercalculated. If one designs the pipe line as per ANSI B31.1...