I have a section of cast iron pipe (it is about 18 inches in length) in the crawl space under my house that has holes rusted in each end that goes in to the joint (bell? the section at the end that is larger than the pipe, where the pipe goes in), I am not sure about the size but I think it is 4 inch. My question is how do you remove this entire section of pipe without damaging the other pieces on each end? Is it possible to remove this section and replace it with plastic pipe connected to cast iron? The new pipe (plastic, I hope) would have to go in the cast iron. I don't know if I have done a good job of explaining it. The straight piece of pipe (with the holes rusted in each end) connects to other cast iron pipes with a flared out end that the pipe goes into. It is the straight piece that needs to be replaced. I had someone try to patch it until I could a get a permanent fix and it still leaks on both ends, so this is definitely a temporary solution. I just want to know what to expect before I call someone to look at it. Since I am a female, some people try to take advantage of my ignorance and I like to be prepared. THANKS!

The enlarged section of pipe is called "Hub". You will not be connecting the same way as the old plumber. You will use 2 different couplings: One shielded coupling on pipe-to-pipe end and the other one, Flex Seal Coupling on pipe-to-Hub end.

You will need either 4" grinder, sawzall with blade for cast iron, or chain cutter. But since your pipe is old and crumbling, the best tool to use would be grinder...

Cut old pipe right at the Hub on one end and as far as you need to go on the other end. Measure the void you just created. Cut new ABS or PVC section of pipe that is about 3/4" shorter then old pipe. ( I assume you have 3" diameter pipe). Slip 3" Plastic x 3"Clay Flex Seal Coupling on and all the way over the new pipe. Insert No-Hub coupling (aka Shielded coupling) on the old pipe and fold it backwards. Insert end of new pipe into Shielded coupling and align the other end with the Hub. Slide Flex Seal coupling over the hub and tighten 2 s.s bands. Flip shielded coupling over new pipe and slide metal bend over it. Tighten the bolts.

You don't have to actually insert new pipe into the hub. Just cut it as close as possible. New pipe will be touching the hub but will not be inserted inside.

You could also cut off the Hub completely leaving you with same diameter pipe . Than you would omit using Flex Seal Coupling and you would use 2 shielded couplings.