This question pertains to a Dismantling Joint to be installed for easy Valve removal. Does the flange which forms a part of the dismantling joint have the same Flange thicknesses as that installed in the Pipeline.
Dismantling joint flanges should be specified to the same standard as any other of the flanges in the piping system i.e. ASME B16.5 or similar. I am not aware of a relaxation in any of the national piping design codes which permits otherwise.
Yup ...the flanges on valves are the same as the mating flange. BUT, ease of disassembly is a factor of piping configuration and not so much flange dimensions. If all your valve are butted up to each other you may have real "fun" getting everything back together. And if it's a ring joint flange... well you won't have ANY "fun" at all! *G*
GOOD LUCK! ...Mark