I am trying to find any type of standard dimensions for a stainless steel pre-fabed elbow with flanges. Everything I have found so far is all butt-welded elbows, etc.
I think you need to use ASME B16.5 for the dimensions of the fitting and ASTM A-217 for the material. It will depend upon pressure/temperature class and what piping Code you must satisfy.
ASP STAINLESS STEEL MSS FLANGES & FLANGED FITTINGS
General dimensions conform to MSS-SP-51. Dimensions of Bolt Hole and Circle Diameters correspond to ANSI B16.5. Cast MSS Flanges and Flanged Fittings are manufactured from material conforming to ASTM-A-351 (CF8/304 or CF8M/316); Forged MSS Flanges are manufactured from material conforming to the chemistry of ASTM-A-182 (F304 or F316) in a proper state of heat treatment to provide desired mechanical properties and corrosion resistance. MSS Flanges and Flanged Fittings are suitable for use at pressure/temperature ratings for MSS-SP-51 Class 150LB Flanges and Flanged Fittings,.
I guess I should have mentioned that these flanged fittings are castings and if you need wrought tubular products you will be looking at a fabricated component. The fabrication can be made using Standard components that are "listed" by the piping Code.
Could you expand on what it is you are looking for and what your usage will be?
I am looking for the dimensions of a pre-flanged short radius 90* elbow for a 6" stainless steel 316 AWWA C207 class D (100psi). I think I found it but still not convinced. I am seeing the center to face dimension is ~8 inches.