How to Cut Carbon Steel Tube?

There are many ways to cut carbon steel tubes (cs tube), such as oxyacetylene gas cutting, air plasma cutting, laser cutting, wire cutting, etc., can cut carbon steel. There are four common cutting methods:

(1) Flame cutting method: This cutting method has the lowest operating cost, but consumes more fluid seamless tubes and the cutting quality is poor. Therefore, manual flame cutting is often used as an auxiliary cutting method. However, due to the improvement of flame cutting technology, some factories have adopted multi-head flame cutting machine automatic cutting as the main method for cutting fluid carbon steel seamless tubes.

(2) Shearing method: This method has high production efficiency and low cutting cost. Medium-carbon seamless tubes and low-carbon alloy structural steel tubes are mainly cut by shearing. In order to improve the shearing efficiency, a large-tonnage shearing machine is used for double shearing; in order to reduce the flattening degree of the end of the steel tube during cutting, the cutting edge generally adopts a shaped blade. For seamless steel tubes that are prone to shear cracks, the steel pipes are preheated to 300°C during shearing.

(3) Fracture method: the equipment used is a fracture press. The breaking process is to use a cutting torch to cut all the holes at the predetermined breaking liquid pipe, then put it into a breaking press, and use a triangular ax to break it. The distance between the two points is 1-4 times the diameter Dp of the tube blank.

(4) Sawing method: This cutting method has the best cutting quality and is widely used in alloy steel tubes, high-pressure steel tubes, and fluid seamless tubes, especially for cutting large-diameter fluid seamless steel tubes and high-alloy steel tubes. Sawing devices include bow saws, band saws and circular saws. Cold circular saws with high-speed steel sector blades are used for cold sawing alloy steel tubes; cold circular saws with carbide blades are used for high-alloy steel saws.

Precautions for carbon steel tube cutting:
(1) Galvanized steel tubes and carbon steel pipes with a nominal diameter less than or equal to 50mm are generally suitable for cutting with a pipe cutter;
(2) High-pressure tubes and tubes with a tendency to harden should be cut by mechanical methods such as sawing machines and lathes. If oxyacetylene flame or ion cutting is used, the affected area of the cutting surface must be removed, and its thickness is generally not less than 0.5mm;
(3) Stainless steel tubes should be cut by mechanical or plasma methods;

Other steel tubes can be cut with oxyacetylene flame.

How to Cut Steel Pipe Quickly and Efficiently?

1. Marking and Measuring
Draw a "circle," not an "arc": Use a square (combination square) or pipe marking tape (Pipe Wrap) to draw a line around the pipe. Making sure the cut line is perpendicular to the pipe's axis is the first step to a perfect cut.
Use a template: For large-diameter pipes, you can wrap a piece of paper or cardboard around the pipe and mark along the edge.

2. Securely Secure
This is one of the most important techniques: Use a vise or C-clamp to securely secure the pipe to the workbench. The cut should be supported on both sides, but the overhang should be minimal to prevent weight from deforming the pipe or pinching the saw during cutting.
Protect the pipe: Place copper or aluminum sheets or old towels between the vise jaws to prevent the jaws from scratching the pipe surface, especially for galvanized pipe or where aesthetics are important.

3. Tool Selection Method
Use an angle grinder (most versatile)
Use a pipe cutter (most precise)
Use a bandsaw (best quality)

4. Cleaning and Finishing
Regardless of the tool used, deburr the cut afterward! Use a file, scraper, or angle grinder with a flap/wire wheel to thoroughly remove all sharp edges and burrs inside and outside the cut. This is a good habit to avoid scratches and ensure the quality of subsequent processing.

Quality Assurance Tips:

1. Prepare for Subsequent Work
If welding is required: The cut must be absolutely clean, free of burrs, oil, paint, and mill scale, and the appropriate bevel must be ground to meet welding requirements.
If threading is required: The cut must be flat and perpendicular; otherwise, the tap will be difficult to align, resulting in crooked threads and leaks.
For socket joints: Simply remove all internal and external burrs.

2. Avoid Overheating the Material
Especially when using an angle grinder, the high-speed friction generates significant heat, which can cause localized annealing (bluing) or deformation of the steel pipe. Intermittent cutting can be used to allow the material to cool. Overheating can also damage the cutting disc and increase the risk of a blown disc.

3. Choose the Right Tools
For thin-walled, small pipe (< DN25): A pipe cutter is preferred for best results.
For medium- and thick-walled pipe (DN25 - DN100): An angle grinder is the best choice.
For thick-walled, large-diameter pipe: Consider using a bandsaw or flame/plasma cutting (the latter requires extensive post-cleanup).

Final advice: 

Practice is key to success. Before cutting a serious part, practice on a piece of scrap material to familiarize yourself with the tool's characteristics and feel. For critical applications, if you're unsure, it's best to seek professional assistance.

Read more: How to Bend Carbon Steel Pipe? or Carbon Steel Pipe Sizes Chart