How to Cut Cast Iron Pipe

Knowing how to cut cast iron pipe is an essential skill if you plan on doing any plumbing work on an older home. Almost all homes built before 1960 have some cast iron plumbing, and some local building codes still require it for some basement work. There are three basic methods for cutting cast iron pipes, one of which can be used for almost any plumbing situation.

The first, and least effect method of cutting cast iron plumbing is to use a hacksaw. Although a hacksaw will eventually cut through the pipe, you may require several blades before the entire cut is complete. Using a hacksaw will require a lot of patience, so reserve this method when no other options present themselves.

The second method uses a ball-peen hammer and a cold chisel to break the pipe. This method is very effective because cast iron, though strong, is also very brittle. To cut cast iron plumbing using this method, draw a line around the circumference of the pipe with chalk or a pencil. Then using the hammer and chisel, make marks around this line, rotating the pipe. After only a few rotations, the pipe will break along the line.

Using the hammer and chisel method is very effective, but only if you have access to all sides of the pipe. If you don't, you must use another method to cut the pipe. Also, imperfections of the cast iron may cause the cut you create to be jagged or uneven. Any pieces that stick out can be removed by gripping them with an adjustable wrench and using the hammer to strike the uneven area. The unwanted pieces should then be able to be removed.

The third method of cutting cast iron pipe is the one used by professionals. It is by far the easiest way to cut cast iron plumbing, but it also requires a piece of specialized equipment: a snap cutter. A snap cutter does not actually cut the pipe in a traditional sense, rather it breaks the pipe at a specified place. A snap cutter is essential if your cast iron plumbing is already in place and you do not need to remove it during your plumbing renovation.