When purchasing valves from a valve company is leak testing of valves by a supplier usual practice or a requirement of a standard? (Not pressure testing, just checking if there is any leakage over the

I am trying to determine the inlet pressure to a throttle valve.

Could somebody help to calculate the maximum flow through a 1" globe valve say 1/2" port size? Basically I have a small barrell with a 0.02 m3 volume at 1440 psig. There is one 1" globe valve connecte