Cutting method and post cutting treatment of straight seam steel pipes

Straight seam steel pipes are widely used in many industrial industries, from natural gas transmission pipelines for oil to building structural supports, all of which rely on their presence. In practical use, according to different engineering requirements, it is often necessary to cut straight seam steel pipes. The selection of cutting methods and the treatment after cutting are crucial, directly affecting the quality and performance of the steel pipes.

Common cutting methods for straight seam steel pipes

mechanical cutting

Mechanical cutting is one of the more traditional and commonly used methods. Among them, the grinding wheel cutting machine is a common tool that uses high-speed rotating grinding wheels to cut steel pipes. When operating, fix the straight seam steel pipe in the appropriate position, turn on the grinding wheel cutting machine, slowly press down the grinding wheel blade to make it contact with the steel pipe and gradually cut in. This method of operation is relatively simple and cost-effective, and is more suitable for some straight seam steel pipes that do not require particularly high cutting accuracy and have small diameters. However, during the grinding wheel cutting process, there will be a lot of sparks and dust generated, and it is necessary to operate in a well ventilated environment. The flatness of the cut after cutting is generally average, and there may be certain burrs.

Another type is sawing machine cutting, which cuts steel pipes through the reciprocating or circular motion of the saw blade. The precision of sawing machine cutting is relatively higher than that of grinding wheel cutting, and the incision is relatively flat. It is suitable for straight seam steel pipes with certain requirements for cutting quality and moderate pipe diameter. But the cutting speed of sawing machines is relatively slow, and their efficiency is not as good as some other modern cutting methods.

flame cutting 

Flame cutting is the process of melting steel pipes using high-temperature flames generated by the mixing and combustion of gas and oxygen, and blowing away the melted metal with high-pressure oxygen flow to achieve cutting. This method is suitable for larger diameter and thick walled straight seam steel pipes. When operating, first adjust the temperature and oxygen pressure of the flame, aim the flame at the cutting site for preheating, and after the steel pipe reaches the ignition point, open the high-pressure oxygen valve for cutting. The advantages of flame cutting are suitable cutting speed and low cost. For some large straight seam steel pipes, the cutting task can be completed in a shorter time. However, the heat affected zone of flame cutting is relatively large, which can cause changes in the tissue near the steel pipe incision, resulting in significant deformation and stress, and relatively low cutting accuracy.

plasma cutting

Plasma cutting is the process of using the heat of a high-temperature plasma arc to locally melt a steel pipe, and using the momentum of high-speed plasma to blow away the melted metal to form a cut. This method has the advantages of suitable cutting speed, high accuracy, and small heat affected zone, especially suitable for straight seam steel pipes made of difficult to cut materials such as stainless steel and alloy steel. During plasma cutting, the generated arc light is strong, and operators need to take protective measures. Meanwhile, the cost of plasma cutting equipment is relatively high, which may not be suitable for some small businesses or cost sensitive projects.

Processing after cutting

Deburring

No matter which cutting method is used, burrs usually appear at the cut of the straight seam steel pipe after cutting. Burrs not only affect the appearance quality of steel pipes, but may also scratch other components or personnel during subsequent installation and use. Therefore, removing burrs is an important processing step after cutting. Tools such as sandpaper and files can be used to manually remove burrs. For steel pipes with large diameters or batch processing, specialized deburring equipment such as chamfering machines can also be used, which can remove burrs at the cutting edge at a suitable speed and evenly, and perform chamfering treatment to improve the flatness and smoothness of the cutting edge.

rust prevention treatment

The cut of the straight seam steel pipe is exposed to air, which is prone to oxidation and rusting. To prevent rust, it is necessary to perform rust prevention treatment on the incision. The common method is to apply anti rust paint, choose high-quality and strong adhesion anti rust paint, evenly apply it on the surface of the incision, form a protective film, and isolate air and moisture. For some occasions with high requirements for rust prevention, more effective rust prevention methods such as hot-dip galvanizing can be used. The steel pipe is immersed in molten zinc solution to form a layer of zinc on the surface of the cut, providing long-term rust prevention protection.

quality inspection

The cut straight seam steel pipe also needs to undergo quality inspection to check whether the quality of the cut meets the requirements, such as the flatness, verticality, and presence of cracks. At the same time, it is necessary to check whether the overall size of the steel pipe has changed due to cutting, and confirm that it meets the design and usage requirements. Only steel pipes that have passed quality inspection can proceed to the next process or be put into use.