In recent years, the global manufacturing industry has gradually developed in the direction of intelligence and digitalization. In order to better cope with the development form of industrial manufacturing, it is necessary to strengthen the transformation of the manufacturing industry. Developed countries such as the United States, Germany, and Japan have all proposed development measures for the new industrial era for industrial development.SSAW steel pipe is an important technical model for the development of manufacturing technology and plays an important role in the technological development of high-steel large-diameter rear wall spiral seam submerged arc welded pipes. Spiral steel pipe, also known as spiral or spiral spiral steel pipe, is a low-carbon steel or low-carbon steel pipe. Alloy structural steel strips are rolled into pipes with a certain helix angle (called forming angle). The pipes are made of welded joints and can be produced with narrow strips and large diameter pipes. During the forming process of spiral welded steel pipes, the steel plate deforms evenly and the residual stress is light , no scratches on the surface.The ASTM A252 standard specifies the requirements for spiral seam welded steel pipes for pipes and pile foundations, including specifications for pipe manufacturing, chemical composition, mechanical properties, dimensions and allowable deviations.
Principle of AC degaussing method:
SSAW steel pipes (spiral seam welded steel pipes) often need to be degaussed during the production process to improve their performance and safety. Among them, the AC degaussing method is one of the most common methods. During the welding process of double-sided screw-threaded submerged arc welded steel pipe (SAW), the internal welding adopts DC welding method. Due to the large current in the internal welding wire and the welding head, a strong magnetic field is generated. Under the action of this magnetic field, the steel pipe body is magnetically Moments acquire or tend to acquire alignment in the same direction as the external magnetic field. When the welding is completed and the magnetic field gradually decreases until it disappears, due to the hysteresis phenomenon, there is still a residual magnetic flux density on the pipe body. This is what we usually call the residual magnetism phenomenon. The existence of residual magnetism causes the direction of the electron beam of the image intensifier to be deflected, and the image of the The detection rate. With the improvement of pipeline steel grade and the replacement of image intensifiers in X-ray television systems, the influence of residual magnetism is particularly prominent and the existence of residual magnetism will cause arc deflection during pipeline girth welding butt joints, affecting the welding quality.
The AC demagnetization method is a technology that uses alternating magnetic fields to demagnetize SSAW steel pipes. Its principle is based on the hysteresis phenomenon and eddy current effect in electromagnetism. When the alternating magnetic field acts on the SSAW steel pipe, the magnetic domain will change periodically, causing the magnetization intensity to also change, thereby gradually weakening the original magnetization state in the magnetic material, and ultimately achieving the purpose of eliminating magnetization.
The process and steps of Principle of AC degaussing method:
1. Wrap a coil around the outside of the steel pipe, pass the alternating current through the coil, and slowly reduce the current of the alternating current until it drops to zero. Demagnetization results: The physical properties of the spiral steel pipe have not changed. However, when encountering the external magnetic field again, the spiral steel pipe is also magnetized.
2. Through the heat treatment process, more thorough demagnetization can be achieved. However, after demagnetization, the hardness and stiffness of the spiral tube will change. If it encounters an external magnetic field in the future, and the magnetic field is removed, the steel tube will basically have no residual magnetism.
3. The heat treatment process is roughly: heating to a certain temperature without oxygen, and then slowly cooling to room temperature over 72 hours.
Application scope:
The AC degaussing method is widely used in the production and processing of various types of SSAW steel pipes, especially for steel pipe products that require high precision and high performance. Main application areas include:
Oil and Gas Industry: SSAW steel pipes used to transport oil and gas require frequent degaussing to ensure the safe operation and stability of the pipeline system.
Marine engineering: Steel structures such as submarine pipelines and offshore platforms are susceptible to magnetization in the marine environment. Degaussing can reduce interference with navigation and communication equipment.
As a common method for demagnetizing SSAW steel pipes, the AC demagnetization method can effectively eliminate the magnetization effect in the steel pipe and improve its performance and safety by utilizing the principle of alternating magnetic field. In practical applications, degaussing equipment and parameters need to be reasonably selected according to specific circumstances to ensure that the degaussing effect meets the requirements.
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