Before building codes changed, homes used to have sewer pipe made of clay (or of lead or cast iron). Today, codes dictate that most sewer lines be made of either PVC or ABS (Acrylonitrile Butadiene Styrene) hard plastic pipe. When older clay pipe gets damaged, it needs to be fixed quickly as spilt wastewater can be a health hazard. This is done by cutting out the damaged clay pipe section and replacing it with the same diameter PVC pipe. The pipes join to each other with flexible rubber couplings.
Mark the clay sewer pipe six inches on each side of the broken/damaged area. Make a straight cut through the clay pipe at both marks using a reciprocating saw. Remove the cut section of pipe, and scrape off any clay fragments from the cut pipe ends with a utility knife.
Measure between the two existing pipe cuts and cut a section of PVC sewer pipe to this length (use a handsaw, circular saw or mitre saw). Scrape away burrs from the cut pipe end.
Wet the outside ends of the clay pipe cuts with water. Push a flexible rubber coupling fully onto each clay pipe end. Wet the outside PVC pipe ends and position the PVC pipe section between the clay pipe ends. Push both rubber couplings halfway onto the PVC pipe ends so that the couplings are half on the clay pipe and half on the PVC pipe. Tighten the metal hose clamps around the ends of each coupling with a screwdriver.
If a reciprocating saw is not available to cut the clay pipe, use a hacksaw.