I won't suggest that parting off 2" dia is nothing but it really isn't a large cut.As far as theory is concerned, I have passed that and for more years than I wish to recall, I CAN PART OFF SUCCESSFULLY.
The only possible problem which could arise is that the part - parted off will nip between centres.
None of these 'taking endless bites of the cherry' and that plunge cutting and starting a new cut and all sorts of variations which would baffle . Paganini. My set up is designed to part off TWO whole inches in diameter- and that's it. Enough to say that I have another lathe-- and have the casting to make another satisfactory parting tool. All That I have to do is put a sub plate under the thing and chew a few millimetres off the casting 'foot'
When you part off even a 2" dia piece it is important that you 'catch the cutoff - - - - if you aren't stabilizing the piece and it starts to wobble - - - well it can take out not only the part off tool but can drag the piece right out of the chuck - - - - things get interesting then - - - - NOT a lot of fun though!
I've found trying to using a parting tool on the end of the piece can get very challenging.
In this case the smaller the diameter the tougher it gets.