This is 1941 ranch house with a cement floor between the main floor and basement. It has cast iron pipes. The flange has finally rusted away. The hole is an oval shape that the pipe goes through and it looks like they used grout or some type of cement between the pipe and base of the flange to wedge the pipe for rigidity. I have access to everything through the unfinished basement. It looks like there is something like lead holding the flange and pipe together. How do I remove the old flange? Once I get it off, I think I have to attach a replacement flange to the pipe as was done before, because the hole is too large and there is not enough surface for 4 bolts, only the back two. I need to know how to remove the old flange and replace it.