Do you know the chemistry of the corrosion process? Clearly,it isn't oxidising the iron, but is it the iron that's ionising? Is it relying on the impurities in the water, or do you still get corrosion with "pure" water?
I don't suppose you know of a book reference, do you?
No I do not know all the chemistry, I know it happens.
I had a good friend who was a chemical engineer that explained it all to me on more then one occasion, now deceased.
Another problem we touched on was expansion. Yes the coefficient of expansion between copper and stainless are close, but the material is different.
In a Stanley boiler, the tube sheets on a 14-inch high boiler with copper tubes crown .030 as the copper tube expands longer then the steel drum. .015 down and .015 up.
The tubes around the outer sides either move and slide in there holes or compress in there length. Most likely compress, or tends to ark in there length or there would be constant leaking.
If stainless is used itís a much harder material and I donít think it would compress. If it were welded in it still has to come under tension or compression. Not good.
I think I might know another way of scorching your boiler. If your pump rode brakes but you don't know it has happen and your sight glass has a water mark on it and you think that's the true water level wouldn't you then scorch your boiler when water in the boiler is empty? I may have a way to stop that happening. clean your sight glass reasonably regulary and after every jorney/steam up blow the sight glass down. Old Timer