How To Cut A Cast Iron Pipe With An Angle Grinder

Kellan Jansen
by Kellan Jansen

Cast iron pipework was once the go-to material for most home drainage and sewer pipe applications. Although it fell out of style in the 1970s, you’ll still find cast iron pipework in most older homes.

If your house has a plumbing system that features cast iron pipes, you may find yourself needing to cut into it from time to time. One of the best ways to do this is with an angle grinder.

To cut a cast iron pipe with an angle grinder, you’ll need to place it on a workbench or use riser-clamps to lock it in place. Then, turn on the grinder and cut around the pipe to create a uniform groove. Allow the grinding wheel to penetrate a single point of the pipe and finish by cutting around that point.

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What Do I Need to Cut a Cast Iron Pipe?

Cast iron pipe has gotten a reputation for being difficult to work with. However, you’ll find that cutting into it with an angle grinder is actually a fairly straightforward task.

One thing to note before getting started is that not every angle grinder will be able to complete the job successfully. If you currently own a cheap grinder, then you’ll probably want to upgrade before getting started. Low-quality angle grinders simply can’t provide you with the strength necessary to cut through thick cast iron pipe.

You’ll also need to equip your angle grinder with a wheel that’s strong enough for the job. A high-quality cutoff wheel should work fine. However, diamond wheels work best for this. You may want to purchase one if your cutoff wheel isn’t the best.

Once you’ve set up your angle grinder, you won’t need much else to cut through a cast iron pipe. Finish your preparations by gathering the following materials:

  • Work gloves that provide at least basic impact protection
  • Wrap-around safety glasses
  • Steel-capped safety shoes
  • Flame-resistant work clothes
  • P2 or P3 respirator mask
  • Riser clamp or workbench with a bench vice

Where Should I Cut Cast Iron Pipe?

The next decision you need to make is where you’re going to make your cast iron pipe cuts. Ideally, DIYers should do this on a workbench. Placing the pipe in a bench vice will make the job easier for you.

However, if you have to cut through a cast-iron pipe, chances are you’re not working in ideal conditions. For example, you may have some pipe under your home or in a dug-up pit that needs to be cut.

You can use an angle grinder to cut through a cast iron pipe that can’t be placed on a workbench. Just make sure that you don’t start working until you’ve supported the pipe. The easiest way to do this is with a basic riser clamp.

Riser clamps are important to use because they prevent the cast iron pipe from falling out of place once the cut is complete. Cast iron pipe is notoriously heavy. This means yours could cause serious damage if you don’t support it properly while working.

How to Cut Cast Iron Pipe with an Angle Grinder

Once you’ve gathered all of your materials and decided where to work, you’re ready to start making cuts. This part of the process isn’t too complex. Just make sure that you follow the following instructions closely to keep yourself safe and ensure the job is successful.

  • Fit your cutoff or diamond wheel to your angle grinder.
  • Use chalk or another tool to mark the portion of the cast iron pipe you want to cut.
  • Put on your protective gloves, shoes, clothes, and mask.
  • Secure the pipe by using a workbench vice or a riser clamp. Riser clamps should be positioned above any supporting points for optimal safety.
  • Turn on your grinder and begin working it around the part of the pipe you’ve marked.
  • Once you’ve created a groove that wraps around the pipe, allow the grinder to penetrate through a single point.
  • Starting from the point of penetration, continue working around the pipe until you’ve finished the cut.
  • If necessary, use a cold chisel to snap the pipe off completely. Do this by simply driving the chisel through the last remaining connection point.
  • Repeat steps 1-8 as much as needed until you finish your cast iron cutting project.

Can You Cut Cast Iron Pipe in a Tight Space?

Cast iron pipes can often lie in some of the most difficult locations to reach around your home. Although cutting this type of pipe can be challenging, it certainly isn’t impossible. You just need to be smart about how you do it.

More specifically, you probably shouldn’t use an angle grinder if you need to make a cut in a tight space. Angle grinders can produce a ton of sparks. That’s the last thing you want in a tight work environment.

If you’re going to be working in a tight space, utilizing a reciprocating saw may be a better choice. You can attach a carbide-tipped or diamond blade to the saw and it will cut into cast iron without any problems. This lets you make the cuts you need to make without producing any hazardous sparks.

Can You Replace Cast Iron Pipe with PVC Pipe?

Since about 1975, most new construction projects have used PVC pipe in place of cast iron. PVC is easier to work with and has a number of benefits that make it a better choice for home plumbing.

After you’ve cut your cast iron pipe, you may be interested in splicing in PVC Pipe to your existing line instead of laying a new segment of cast iron pipe. This is possible but can be a bit difficult to accomplish on your own.

To get this done, you would need to start by removing any lead from the pipework. Doing this will enable you to install a service bushing. This, in turn, allows you to transition from cast-iron to PVC without having to worry about future leaks.

Once you’ve done that, you can do a dry run by connecting the PVC pipe without applying any primer or glue. This will let you know if there are any problems you need to fix before making the solution permanent.

Finally, you can finish the job by installing any rubber couplings or stainless steel clamps you plan on using. Once you’ve done that, you can apply your primer or glue to finish the project.

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Related Questions

What’s used to join cast iron pipes?

If you’re replacing an old section of cast iron pipe with a new one, then you may need to know how to join it to the existing system. There are several different materials you can use to get this job done.The most commonly used materials for doing this are lead, cement, and sand. The material that you use should be based on the purpose for which the pipe will be used. Consult with some online resources before making a decision.

Is cast iron plumbing bad?

Cast iron plumbing certainly isn’t optimal. However, that doesn’t necessarily mean you need to replace yours right away.A replacement may be needed if you have slow drainage, evidence of interior pipe corrosion, broken seams, or patches of rust. If you’ve noticed none of these signs, then chances are your cast iron plumbing system is still working fine.

Kellan Jansen
Kellan Jansen

Kellan is a content writer who specializes in everything DIY. When he's not behind the keyboard, he enjoys spending time with his pets, playing music, and geeking out about basketball. He hopes to make your home improvement projects a little bit easier to accomplish.

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