Stainless steel seamless pipe has a high requirement on quality in the environment of high temperature and pressure. Improper machining operation process in the production process may roll or drawing die setting improper reasons and on the pipe, as a result of a crack. Folding, warping, scratches, or strain, surface and internal defects. In order to ensure seamless pipe quality, according to the relevant technical standards for products, seamless steel pipe production line required nondestructive testing of surface and interior. Commonly used eddy current testing and magnetic flux leakage detection technology.
Eddy current testing is to establish a non-destructive detection method, on the basis of the electromagnetic induction it sine current excitation probe coil, the induced electromotive force generated when the probe near the Seamless surface, the alternating magnetic field around the coil rims surface generates an induction current, i.e. vortex. The vortex is also the feelings generated magnetic field acting on the coil, thereby changing the electrical parameters of the coil. The loss resistance of the vortex channel and the eddy-current generation of anti-flux, but also reflected to the probe coil, changing the size and phase of the current in the coil, which changes the impedance of the coil. The probe in the seamless steel surface is moved relative defects encountered, so that the reaction of the eddy current magnetic field of the coil, causing the change of coil impedance, thereby measuring the amount of change identified seamless steel pipe surface defects.