Generally when you are working on a set of rings that have been
soldered together, you have no idea of what additional work has been
done on the shanks. If you try to separate the two rings with a
torch you may have old sizing sections or shank replacements come
If the shanks are heavy enough to warrant it you should use a very
fine saw blade to cut the rings apart and then clean both rings up.
If the shanks are worn or very thin you may want to cut the shank
off and reshank both rings.