First, thanks for all the feedback.
I guess my original post was not clearly stated.
I want to remove the pipe from the hub - Not - cut it off above the hub.
The reason for this is that once the vertical riser is removed the cast will be plugged at the hub, then a concrete slab poured on top of where the hub is located. To get the slab depth needed the vertical needs to be removed not cut. Breaking the hub with a sludge will also - Not - work as it goes though a concrete block wall and any extra force used may destroy the block which will create another and bigger problem.
isola96 -- one option maybe to cut off vertical above hub and then try and saw cast from inside out. Tried one metal cutting blade and teeth failed after less than a minute. Have heard Lennox blades listed for cast do -Not- work either.
Will check on tungsten.