As surge vessel is only of use during a surge event.
It sounds a little odd to have design pressure and operating pressure so close , but what you may have is a requirement to pour fluid into the system on a trip or shutdown to prevent a vaccuum and flow reversal occuring.
You need to look closely or re-do the transient analysis. you can't tell anything from a steady state or a piping drawing.
"The surge vessel is non operational for more than 2 years" !!!
So it won't be doing it's job then.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.