Steel Pipe Leakage Magnetic Nondestructive Testing Technology

Magnetic flux leakage inspection is by magnetized ferromagnetic surface mayonnaise out of the soup into the pass to determine whether there is material defects. Since the magnetic permeability of ferromagnetic materials is greater than the permeability of other media, so most of the magnetic flux through the city from inside the ferromagnetic material. If the surface of the optical parts of ferromagnetic materials, uniform and compact interior, no cracks, no inclusions, after the material is magnetized magnetic material parameters inside the same everywhere, all the uniform magnetic field lines through dense ferromagnetic material inside. If the material or internal defects and external surface, the mapping of the magnetoresistive material trap is increased, so that the magnetic flux corresponding to the occurrence of distortion: a portion of the magnetic flux passing through the block notch; another part of the magnetic flux to bypass the defect through the surrounding ferromagnetic material; still part of the magnetic flux leakage turn on the outer surface of a ferromagnetic material, bypassing the defective material and re-enter. Abduction magnetic detecting the first condition is the method of using the regulated DC magnetization fully magnetized ferromagnetic material, when the inside and outside surface of the material or material defect, the defect section of the magnetic permeability capacity than small cross section normal capacity, according to a continuous magnetic field lines principle and the principle of magnetic shielding, magnetic field lines can not exchange defective parts in the interior materials, must swell outward, some of which leaked this part of the expansion of class lines of force to the workpiece surface, the sensor surface laminating speed scanning. could be sonar to. Therefore, the most significant feature is that the magnetic flux leakage to the gun side of the material within the outer surface and internal defects having a higher detection capability. 
On the basis of the magnetic detection technology intestine appeared on inspection side metal magnetic memory technology, it can be effectively applied to in-service equipment early damage detection side. It suddenly this principle is: the ferromagnetic material defects or if the defect before the formation of the city changes the role of a district emblem magnetic beads in place, will cause changes in the magnetic field, which is called the magnetic memory characteristics. Due to their genetic equipment components. Emblem concept defects in the manufacturing process, i.e. the formation and subsequent operation in the presence of load stress of the metal magnetic memory shown a cumulative manner, the size and direction of the operation load of the force member The changes will cause changes in the value and direction of the magnetic A, the magnetic field on the surface of the metal components soup scan detection side. could determine the stress concentrated area, thus indirectly determine the possibility of the ferromagnetic member flawed. Metal magnetic memory method does not require pretreatment of the surface of the device, it can quickly and accurately diagnose the equipment, so as to achieve an early pre-Pu equipment fatigue damage, aim to facilitate the timely control.