No - flanges will have rubber gasket and stainless bolts
Thanks for the reply. I have the impression that the stainless bolts don't provide electrical insulation, and I didn't see anything in the manufacturer's documents to indicate that there were insulating sleeves and washers.
I did a LOT of reading after I posted this question, and came to recognize that about 80% of people who post on the topic of dielectric unions think they are worse than nothing (and about 20% think they work great, go figure).
I also read (somewhat ambiguous) California plumbing code that indicated that "dielectric fittings" could be used. It was ambiguous on the point of what constitutes a dielectric fitting. I saw that one large municipality in California considers a 6 inch brass nipple to be a dielectric fitting, but I'm currently contemplating "dielectric nipples", which are shorter but have a plastic liner in the nipple. I'm currently leaning toward the latter but would be interested to hear what people's experience has been with either approach. From an electrical safety perspective, I like these alternatives because it keeps the electrical piping all electrically bonded together. What I don't know is which approach would be better at limiting corrosion.