I would like to ask you about control valve and pipe size.
I have a control valve for Sea water service, installed on 3 inch pipe, calc Cv is 8. it reduces pressure from 174 barg to 6.9 barg for flushing service.
when i check with Fisher, they said that 3 inch valve size, high pressure trim, 3 stages must be used. The attached file is preliminary sizing and their catalog (the 4 inch inlet/outlet line size are not correct, it should be 3 inch but Fisher confirmed that the results is not change if inlet and outlet line are 3 inch).
It means control valve and line size are the same. I've never seen this case in my previous project and then i would like to ask it can be happend in engineering design.
Any feedback is appreciated.