I need to replace a short vertical section of cracked 4" cast iron sewer line. The section to be replaced is a little less than 4 feet long. The top of the cast iron above the connection is already supported so it can't drop down when I take out the bad section.
What I am thinking of doing is breaking out the bad/cracked section of cast iron, and hopefully ending up with a clean male end of the cast iron at the top, and a clean female end of the cast iron at the bottom. To connect the PVC to the cast iron at the top, I plan on using a rubber connector.
My question is about the bottom part. I would like to insert the PVC into the female cast iron fitting at the bottom and then seal that connection with something. I am thinking that since it is a vertical connection, and it is not under pressure, this should be able to work without the fitting leaking. Is there some sealant or product that will work for this?
Is the alternative to look for a rubber fitting for the bottom that is big enough on one end to go over the extra large cast iron female fitting and regular 4" size on the other end for the PVC male end?