Thanks to you both hacksaw and krsmani77.
krsmani77, I am talking about downstream pipe temperature.
The fluid depressurized thru a piping system then flare system.
Thanks again for your help with my best regards.
During depressuring a portion of pipes more than 1h and half is taken. A Restriction Orifice (RO) is used to depressurize the system to avoid reaching -46 deg-C (pipe design temp.)The RO pressure drop was designed for 300 bars.
In fact the pressure drop is about 200 bars, how can we determine...