I am remodeling my bathroom and removed a bathtub to convert to a shower. The photo is what the piping tied into the main looks like. Without removing part of the main, can I cut the 1 1/2 pipe where it meets the wye and cut the inside of it? (Circled. It looks like it is a 2inch reducing to the 1 1/2inch.)
I have no idea whether you can meet code doing this, but I have, in a pinch. It's a low-pressure situation (assuming no joint stress from misalignment), so it's just a matter of closing all gaps.
The key is to remove all the material from the elbow, along with the cured cement, without removing too much material from the wye. If you can do that, the cement will dissolve enough plastic to form a new weld.
There are dedicated reaming tools available, but careful use of a grinding wheel in a rotary tool works, or a sanding drum in a drill. Note that once you grind past the original surface of the pipe it gets softer, so grinding goes faster. Brace the tool well.
Then, use good installation technique: Coat both parts evenly with cement, give it half a twist as you insert, hold for at least 30 seconds. Tool excess cement from the outside to form a cove against the hub as a last line of defense.
Yes. The tool you need is called something like socket saver, hub saver, fitting reamer. It goes in a drill and has a pilot section that rides the pipe in the socket to guide a blade to cut the pipe while leaving the socket intact for re-use.
They are available in different qualities at different price points. You might want to check with the local tool rental to see if you can rent a high-priced-easier-to-use-better-quality one rather than buying a cheap one; though either will likely cost less than hiring a plumber to come use theirs.
See https://diy.stackexchange.com/a/245650/18078 for pictures of the tools
