Step 7 · Cut the PVC Replacement Pipe
Measure the exact distance between the two ends of the cast iron pipe. Now, measure your two shielded transition couplings; specifically, measure the distance from the end of the coupling to the internal pipe stop. Subtract the combined space that the two couplings will occupy from your initial gap measurement. This final number is the exact length to cut your new PVC pipe. Use a PVC handsaw or tubing cutter to cut a piece of Schedule 40 PVC pipe to this length. Deburr the inside and outside of the cut ends with a deburring tool or sandpaper.