As I was trying to break loose the galvanized pipe from a Tee joint, the pipe snapped at the joint. I applied PB blaster to the rusted connection and let it set for about 30-45 minutes before attempting to loosen it. Is there a way to remove the joint without cutting off any of the remaining pipes?
You may have another convenient option. Since a part of the piping is already PVC with glued fittings you could remove the iron pipe and fittings back to other joints and then replace this problematic TEE and adjacent iron piping with PVC pipe and PVC fittings. You would then adapt back to the iron pipe at those other joints.
The glued PVC fittings are low cost and really easy to work with.
I'd borrow or buy an "inside pipe wrench", then heat the T fitting with a torch for a bit to expand it and give it a crank.
If you're careful while you work you can make two cuts in the broken off section until just above the threads on the fitting. That will allow you to knock out a section with a cold chisel. Depending on how bad your luck is running you may need to repeat the process once or twice before you can get the entire piece loose. Clearly the key to success is patience to avoid damaging the fitting.
If you do heat it to loosen things up, keep in mind that it's going to take a while with a propane torch. That's quite a lot of mass and it may be a matter of literal minutes before it pops. You can't go wrong with a shield to protect the stuff behind it either.