I believe there is some information on features/similarities and differences of MANY types, specifications, and some comparative manufacturing features of iron and steel flanges, apparently collated by an API Task Force not long ago at
Technical book stores also carry the CSA versions in both the imperial and metric versions. They go up to NPS 60 and are fully complete for what you are looking for, blind, RFWN, threaded, weld-on, what have you.
Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada