Connecting a plastic pipe with a cast iron pipe is a job you can do in a few easy steps. Just because the pipes are made from different materials does not mean they cannot be joined and function properly once combined.
Step 1 - Cut Cast Iron Pipe
Start by cutting the cast iron pipe where you need to connect the PVC pipe. Use your file to smooth the cut and clear any shards or sharp edges from the cast iron pipe.
Step 2 - Attach Coupling
Attach one side of your coupling over the cut end of the cast iron pipe and tighten the screws tightly to secure the coupling. Once one end of the coupling is secured to the cast iron pipe, you can get your plastic pipe.
Step 3 - Attach PVC Pipe
Next, you should insert the plastic pipe into the coupling, creating a connection between the cast iron pipe and the plastic pipe. Tighten the remaining screws on the coupling making sure the screws are tight. Test the connection for leaks by running water through the pipe. If you do have a leak, check the tightness of the screws on the coupling and try tightening them more if possible.