Well Casing Blowdown

Dear all,
Currently I am working on a wellhead platform offshore project and and would like to know more about well casing depressurizing. Appreciated to anybody to clarify these items:
1-Normally we need to consider a high pressure alarm for casing; which setting we should consider?
2-how we can realize that design temperature of blowdown downstream piping is O.K?Can we use HYSYS dynamic depressurizing utility for this estimation? If we can then which initial temperature and pressure we need to consider?


Regards-Mohammad