A1 - because you want the port to be the controlling element, and if the inlet was 0.625 for a NPS 1 valve, that would hinder control. Or if it was 1.375 then you wouldn't have enough for the gasket to seat
A2 - see below. I wonder why they even put that information in the standard...silly...
I'm stumped. I can't find any standard or literature which dictates the ID of a globe control valve. I'm not referring to the port diameter, but rather the bore ID of the flow inlet or outlet. My specific valve in question is a Fisher HP CL1500 RTJ flanges, but I can't seem to find ID of the...