EO double block and bleed valves and pipe class question on the P&ID

[hswang2]

EO feed(OP=12 barg, OT= -25 C) to the reactor (OP=12 barg, OT=215 C),and feed line seems climb upward to the Reactor top.
I am just curious why this liquid fluild piping instead of gas fluid go upward.
Morever, in our process, we don’t use a triconics interlock system with at least 2 - double block and bleed valves to assure isolation of the EO. We use 4 valves.
Could any one professional kindly explain to me what is different in this two chooses?
And, the other piping class question, genarrly the pipe class with more pound limts will have
Higher design temperature limt also?

Thank you very much for your kindly help.

 

[JLSeagull]

By EO I assume that this question relates to ethylene oxide, right?

 

[hswang2]

Yes sir. Your are right.
EO is ethylene oxide.
Thank you

 

[dcasto]

EO safety systems are up to you. If you want a cheap system, then be prepared for a disater.

Yes temperature does derate mainly the flanges and valves MOAP first and they become the limit. You can switch to CrMo or even SS to get get a matching pressure rating at a higher temperature. At 215C, carbon steel flanges derate about 20% in pressure. You'll need to look at the valves individually to assure they and their components are rated for the higher temperatures.