How to Cut Cast Iron Sewer Pipe

Many older houses integrate a sewerage system composed of cast-iron pipes. Cast iron pipes were prominent before the invention of PVC pipes. Older houses may still have these pipes and you may need to replace them upon rusting or damage.

There are numerous tools to cut through a faulty cast iron sewer pipe. The most convenient tool to use is the reciprocating tool with carbide-tipped grit. The equipment achieves a clean cut in a fast and less stressful process.

If you don't have a reciprocating saw, you can use other tools including hackswas, circular saws, snap cutters etc. If you don't have these tools, check other ways to cut metal without tools.

What Can Be Used to Cut Cast Iron Pipe?

Commonly found in older homes, cast iron sewer pipes were primarily used for vents, main drains, and large drain pipes. The cast iron pipes are extremely heavy, tough, and prone to rusting. You can cut out a section of cast-iron pipe using various tools and equipment, as shown below;

Hacksaws

You can use old-fashioned hacksaws with good teeth blades to cut cast iron pipes. Hacksaws involve more handy work; therefore, using this tool requires you to exert maximum force when pushing back and forth. 

Hacksaws result in hard work and are time-consuming, especially when you have to cut several cast iron pipes. Use hacksaws to cut cast iron pipes when you have extended hours and energy to spare.

Reciprocating saws

Reciprocating saws feature an attachment at one end of the tool to help hold the long thin saw blade in place. Once triggered, the long cutting blade moves backward and forward at high speed, cutting through the cast iron pipe.

Reciprocating saws are ideal for cutting cast iron pipes as they make the process a breeze. Before using a reciprocating saw, ensure you have installed the right diamond/ carbide grit long cutting blade. The saw blades result in smooth edges on the cut cast iron pipe.

Circular Saws

You can cut cast iron sewer pipes using circular saws in a quick and less stressful way. A circular saw requires integrating a diamond blade specifically designed to cut cast iron material. The saws result in clean cuts and ensure the pipe has smooth edges.

Snap Cutters

Snap cutters are the best tools to use when cutting through cast iron pipes. The equipment is designed to facilitate quick and easy cutting with smooth and even edges on the pipes. Snap cutters resemble scissors with ratchet handles and a roller chain instead of blades.

Snap cutters are relatively expensive, but you can rent one from a reputable dealer. Place the chain around the pipe and wrap it tightly to use the tool. Then apply force on the handles to cut through the cast iron sewer pipe.

Best Blade for Cutting Cast Iron Pipe

Most traditionally made saw blades are made of carbide grit or diamond grit. But the best saw blade for cutting cast iron pipe is the carbide-tipped blade. Carbide-tipped blades provide improved cutting speed and durability in relation to diamond grit blades.

Carbide-tipped blades come in 3 lengths, including 6 inches, 9 inches, and 12 inches. The 8 teeth per inch (TPI) blade is ideal when cutting thick cast iron pipes. On the other hand, the 20 teeth per inch blade is suited to cutting thin metals and hence not ideal for cutting cast iron.

The best blade cut through cast iron pipes is usually 8 inches long, ¾ inch wide, and approximately 0.04 inches thick.

Step-by-step Procedure on How to Cut Cast Iron Pipe

Before cutting, always wear eye and hearing protection when cutting cast iron pipe. Remember, cast iron is heavy, so handle it carefully to avoid injuries. 

There are numerous tools to help in cutting damaged sections of cast iron pipes. Each tool may follow a slightly varying direction as per the manufacturer, but here are general procedures to follow;

Things you will require include;

• Chalk

• Saw blades

• Snap cutters

• Reciprocating saw

• Eye and hearing protection

When Using Snap Cutters

Step 1: Make a clear path to access the pipe you are attempting to cut. Then, use chalk to make markings/ cut lines on the pipe. Ensure you make the cut lines as straight as possible

Step 2: Place the snap cutter around the pipe. Wrap the chain jaws of the snap cutter around the pipe. Ensure the chain is evenly wrapped and most cutting wheels are against the pipe. Ensure both hooks are placed on the pipe with the open side up.

Step 3: Rotate the ratchet clockwise to tighten the snap cutter jaws. Ensure the snap cutter jaws are square to the pipe and the chain is in place with the cutting line. You can support the cast iron pipe and keep it steady as you cut it.

Step 4: Apply pressure onto the snap cutter handles to cut the pipe. Let the wrapped snap cutter wheels cut into the pipe. Score the pipe numerous times before you make the final cut.

Step 5: If you are cutting a replacement pipe, rotate the pipe slightly before cutting. Then, repeat the mentioned steps on all other marked cutting lines.

When Using Reciprocating Saw

Step 1: Fit the reciprocating saw with a long heavy-duty metal cutting blade. Metal cutting blades are made with diamond or carbide grit to help cut along hard items.

Step 2: Spray the cast iron sewer pipe with a lubricator to help prevent blade wear.

Step 3: Mark the cut lines using a piece of chalk. Hold the iron pipe firmly and make straight cut lines so you’ll end up with smooth and clean edges.

Step 4: Set the saw at the lowest speed and cut at a steady pace. Do not apply undue pressure on the reciprocating saw; let the blade do the cutting work. Too much pressure/ speed can cause the blade to snap.

Step 5: Complete the cut by continuing with the moderate cutting motion until the entire pipe is cut with a single clean slice.

Cutting Cast Iron Pipe with an Angle Grinder

With the right cutting wheel placed on your sturdy angle grinder, you can cut the cast iron pipe with an angle grinder, especially if your pipework requires replacement. Removing cast iron pipe sections is usually tricky when working in a confined space.

Angle grinder swiftly cuts segments of cast iron pipe in a relatively simple process. The tool isn’t recommended for confined tight spaces as it produces an abundance of sparks. Some of the items you will need when cutting cast iron pipe with an angle grinder include;

• Steel capped safety boots

• Flame-resistant long sleeve work shirt

• Wrap-around safety glasses

• A pair of sturdy work gloves

• Respirator mask

• White/ yellow chalk or crayon

Steps to follow

1. Fit the metal cutoff blade to the angle grinder and tighten it using the ratchet tool. Upgrade your cutoff wheel to a decent diamond wheel. Fit the wheel properly, and you are good to go

2. Use chalk or crayon to mark the segments of the cast iron you will be cutting

3. Wear the recommended PPE gear to protect your eyes, ears, and hands

4. If you are operating on-site, secure the pipe in position. Then fire up the grinder and begin cutting through the pipe. Make a groove to weaken the pipe

5. Work around the entire circular section and allow the grinding wheel to penetrate through a single point

6. Since cast iron is very tough, you can use a cold chisel to finish through the remaining segment

What is the Fastest Way to Cut a Cast Iron Sewer Pipe?

The ideal way to successfully cut cast iron pipe is to carry out the process on a sturdy workspace with the pipe firmly held/ clamped. The fastest way to cut cast iron sewer pipe is using a reciprocating saw and a carbide-tipped blade with 8 teeth per inch spacing.

A Reciprocating saw is a reliable tool when operating in a confined space. Snap cutters are also ideal options as they make quick and smooth cuts.

Frequently Asked Questions

Can you cut the cast iron pipe with a soil pipe cutter?

A soil pipe cutter is a reliable tool when cutting cast iron pipe. The soil pipe cutters come in varying sizes and configurations. The tools feature a chain to wrap on the pipe when cutting.

Soil pipe cutters work with tension; hence the sewer pipe needs to be in decent condition for the cutter to work. Severely corroded or rusted pipes are not suited to cut using these tools.

Can you replace the cast iron pipe with PVC?

Yes, especially if you are dealing with leakages and burst cast iron pipes. Cast iron develops rust, therefore, posing potential leaks. You can replace damaged cast iron sewer pipe segments by installing PVC pipework.

Can you cut a cast iron pipe with a Dremel?

No. A Dremel incorporates a small motor that runs at a high rpm. Therefore, cutting cast iron pipe using Dremel may result in the burning up of the tool.

Conclusion

Cast iron pipes are mainly found in older homes where it was mainly used for large drain pipes, vents, sewer pipes, and main drains. As mentioned, there are different tools you can use to cut your old cast iron sewer pipe. Whichever you choose, use it carefully to avoid injuries.

Guest Contributor: Walter Bennett