In Parts 1 and 2 of this guide to replacing a cast iron pipe, you learned how to cut off the old pipe and prepare a PVC pipe for fitting. In Part 3, you will have to position the PVC pipe and fit it into the cast iron pipe, and then position the coupling over the pipe. When you are ready to begin, place your PVC pipe with the coupling added near to the cast iron pipe. Follow the simple steps below to fit the last piece of the PVC pipe.
Step 1 - Sanding Down the Pipe
You should be able to smooth down the edge of the cast iron pipe until it is smooth. Remove any burrs, and ensure that it is not sharp. You should also consider cleaning the edge of the pipe if your fix is being down on a water supply line, as iron shavings may appear in the line of the pipe. Ensure that the pipes are clean and smoothed down before you try fitting thm together.
Step 2 - Making Contact with the Pipe
Lift your PVC pipe up to the pipe. The pipe and the coupling should be very close fitting with the gap that you have cut into the cast iron pipe. You should be able to fit the edge of the PVC into the copper pipe. If there are any problems doing this, then you should try cutting down the PVC pipe until it fits your cast iron pipe properly. The PVC pipe should then be held in position while you screw it into position.
Step 2 - Tighten the Coupling
The coupling should be pressed down onto the cast pipe. Once the coupling is in place, tighten it up using the screw on the metal band. You should be able to tighten it into the edge of the cast iron plate until you feel the resistance of the pipe. You should try and move the coupling around, repeatedly tightening it until you can no longer move the coupling against the PVC pipe. Check the coupling at the edge of the other side of the pipe.
Step 4 - Test the Water
Before you can test that your join is completely secure, you need to turn the water back on. Use your wrench to turn on the water, and then run water until it starts flowing through your replaced line. Listen to the water running through the pipe, and also run your hands along the edge of the PVC and coupling. Check for signs of leaking. If you find any problems, repair the pipe again, otherwise continue to use the new pipe as previously.