Step 2 · Break and Remove the Old Cast Iron Flange
WEAR SAFETY GLASSES AND HEAVY-DUTY GLOVES. First, stuff a large rag into the drain pipe opening to block sewer gas and prevent debris from falling down. Using a cold chisel and a hammer (or small sledgehammer), carefully begin to break the cast iron flange ring. Place the chisel on the top of the flange ring and strike it firmly. Work your way around the ring, creating fractures. Avoid striking the central drain pipe. Once the ring is sufficiently fractured, use a pry bar to lift the broken pieces away. You may need to chip away at the lead and dig out the oakum rope that forms the seal between the flange and the pipe.