The specification puts forward clear requirements for the remanence of the spiral steel pipe
, so it is necessary to grasp the method of degaussing the spiral steel pipe. The communication degaussing method of spiral steel pipe is the most common method now. The spiral steel pipe communicates the degaussing process flow chart, and the coil is wound around the outer side of the steel pipe to communicate the electric current to the coil, gradually reducing the communication current until it is reduced to zero.
Degaussing results: The physical properties of the spiral steel pipe are not changed, but the spiral steel pipe is magnetized once the external magnetic field is encountered again. After the heat treatment process, the complete degaussing can be performed. However, after degaussing, the hardness and rigidity of the spiral steel pipe will change. When the external magnetic field is encountered in the future, the external magnetic field disappears, and the steel pipe will have substantially no remanence.
The heat treatment process is about: an anaerobic heating to a certain temperature, and then gradually cooling to room temperature in 72 hours. In the welding process, the internal welding adopts the DC welding method. The internal welding large line and the welding head part generate a strong magnetic field due to the large current. Under the magnetic field effect, the magnetic moment is obtained or tends to be the same as the external magnetic field. The orientation of the display.
When the welding is completed, the magnetic field is gradually reduced until it disappears. Due to the hysteresis, there is still a residual magnetic flux density on the pipe body. This is what we generally call the remanence phenomenon. The existence of residual magnetism causes the electron beam direction of the picture intensifier to be deflected. The X-ray industrial TV system picture has a "S" type distortion, which affects the natural defects such as pores and slag inclusions, especially the linear defects such as incomplete penetration and crack. Detection rate.