Cast iron pipe rots. It will take a long time, but, eventually, cast iron pipe, the old bell and spigot type, will deteriorate to the point that it becomes punky and soft. You may discover that a section of the old pipe under your house is cracked and leaking. How do you remove and replace it?

Preparation – Choose The Right Tool

1. The first thing to do is rent a pair of soil pipe cutters. Most rental stores, and even some hardware stores, carry these specialized tools and rent them out to their customers. There are two types of soil pipe cutters. One operates with a ratchet handle. This type works especially well in tight places like crawl spaces and in between stud and joist spaces. You loosen or open up the cutter chain jaws with the knob, place the cutter chain around the soil pipe and engage the chain with the jaws, then tighten the knob. Once you have the chain in place and tight, you operate the ratchet handle until the cutter chain breaks the cast iron soil pipe. These tools require some experience to operate successfully. If you are unfamiliar with this tool, ask someone at the rental yard or hardware store to demonstrate it for you.

1. The second type is a large soil pipe cutter that looks somewhat like a pair of pliers with a cutter chain attached to the end of pliers. You need quite a bit of space to operate these cutters. They work great outside and in ditches. Once again, you loosen or open up the jaws with an adjustment handle near the jaws of the unit, place the cutter chain around the soil pipe where you want to cut it, tighten the adjustment handle which should open the handles of the soil pipe cutter far apart. Resting one handle on the ground or against yourself, press the other handle together toward the first one like closing a pair of pliers. If you have adjusted the soil pipe cutter properly the cast iron soil pipe will break cleanly.

The Problem

1. The problem comes in trying to cut that old deteriorated cast iron soil pipe. You have to keep cutting away at it until you find a section of the pipe that is solid enough to cut cleanly.

The Repair

Then clean the outside of the pipe well, slide your Fernco or Mission rubber coupling over both ends of the old cast iron pipe, cut a new section of ABS or PVC DWV (drain, waste, and vent) plastic soil pipe to fit and install the couplings.

Tips and Tricks

1. You can also use no-hub couplings of the proper size to make your connections.

1. The clamps on the couplings should be tightened with a special torque wrench or to 12-inch pounds. Do not over tighten the clamps or they will strip.

1. Note that DWV or drain, waste, and vent plastic pipe is the same or nearly the same outside dimension as cast iron soil pipe. But copper DWV pipe is a different outside diameter entirely and cannot be used in this instance.

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