How to check weld neck flange dimensions?

Weld neck flange dimensions are covered in ASME B16.5 – which covers Pipe Flanges and Flanged Fittings for size NPS ½” to 24” for above NPS 26” to 60” it should be as per ASME B16.47.
During dimensional inspection of flange, you should check for

Outer & Inner Diameter of body
Bolt Circle & Bolt hole Diameter
the thickness of weld end
Length of the Hub and
Straightness and alignment of the bolt hole