I have a ci pipe that appears to be one piece, meaning the pipe and flange are one. Can this be the case? Or is it so corroded I can't tell? Replacing a toilet. If I knew how to imbed I picture I would. Thanks.

It is more likely corroded. Take a screw driver and see if you can scrape off the rust and find the seam between the ring and the pipe. Sometimes it is very tightly put together and over time, corrosion will fill the seam, making it look like one piece

Milo

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