Exhaust Band Clamps
I'd think even that one that is stepped for id/od pipe connecting would be better suited as a butt fit to allow very easy disassembly as the pipes never interface with each other. Just uses the clamp as the "wrap" between the 2 pipes. The smooth wall models are the true 2.5/2.5 butt splice. It even says SLIT fitted id/od connections but id rather keep the pipes free of any additional cuts if this is a true union and not a support application. Dont know how this style would compress a non slit OD pipe onto an ID...ever try and break an egg in your hand by squeezing it? Pretty hard as the force is equally applied to the entire round surface (eg. Submarine hull).
@RustyRatRod I wonder of the slip fit model you have would seal equally well put together as a butt seam and then clamped down. Then you would have no effort required to separate these in 8 years as there would be no Rusty(s) steel pipe to steel pipe bonding.