How to Cut Cast Iron Pipe

Last Updated: June 8, 2021

Cast iron pipes were used before the invention of PVC pipe and was the choice for main stacks and waste drains. Many older houses still have these pipes and you may need to replace them. This article will teach you how to cut cast iron pipe.

Method 1

Method 1 of 2:

Using Snap Cutters

1
Use chalk to mark cut lines on the pipe. Make the lines as straight on the pipe as possible.
2
Wrap the chain of the snap cutter around the pipe as evenly as possible. Ensure that there are as many cutting wheels as possible against the pipe.

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3
Apply pressure onto the handles of the cutter so the wheels cut into the pipe. You may need to score the pipe several times before you can make the final cut.^{[1]
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- You may need to rotate the pipe slightly before making the final cut if you are cutting replacement pipe on the ground.
4
Repeat these steps at all other chalk lines.

Method 2

Method 2 of 2:

Using a Reciprocating Saw

1
Fit your saw with a long metal cutting blade. Many of these blades are made with carbide grit or diamond grit for cutting through hard items.^{[2]
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2
Use chalk to mark your cut lines. Mark the lines as straight as possible. Hold the pipe firmly in place. It may be easier to have another person hold it in place for you.^{[3]
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3
Set your saw at low speed and let the blade do the work for you. Avoid applying undue pressure on the saw that can cause the blade to snap.^{[4]
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Community Q&A

Question

When cutting an existing cast iron vertical sewer pipe in an older home, do I need tie off the pipe going up, or will it stay up on its own?

Community Answer

It's going to depend on whether or not the old pipe is secured already. In many older homes, cast iron wasn't secured to anything, in which case you will want to double wrap rope around pipe and secure above the area you are cutting.
Question

What is the most important aspect of engineering?

Community Answer

Preparation. Nothing is more important than preparation. Fail to prepare, prepare to fail.
Question

Will cutting an iron pipe with a saw cause it to vibrate too much?

Community Answer

As long as you apply the proper amount of pressure while cutting, along with a possible brace depending on the pipe location, you should be fine.

Warnings

Always wear eye and hearing protection when cutting cast iron pipe.

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Follow the manufacturer's directions for your specific tool. Each brand can be slightly different and the directions can vary slightly from the ones given in this article.

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