Try the flexatallic website.
If you're worried about the corrosion of the gasket, then stainless steel is the material of choice since affinity to carbon steels are low. If you are worried of the flange itself undergoing galvanic corrosion, you can paint the component to insulate it from the opposing dissimilar metal.
I've never experienced this to be an issue. What kind of working medium are you using?
Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada