A Method Of Signal Dynamic Compensation In The Steel Pipe Defect Magnetic Flux Leakage (MFL) Testing Signal Based On Lift-off Value Measurement

As the speed of the pipe Magnetic Flux Leakage (MFL) is increasing, the frictionand vibration between the steel pipe and testing probe boots will become sharply.Because of the Lift-off effect, the signal consistency will be worse. The article find amethod to increase the signal consistency form monitoring the state between thesteel pipe and detecting probe boots by measuring the distance between the steelpipe and detecting probe boots.The magnetic leakage field is attenuated as the distance between the steelpipe and detecting probe boots increasing.A detailed calculation of the high speedmagnetic flux leakage testing in must lift off value range by piecewise linearcorrection is showed in this article, it can the control magnetic flux leakage signalconsistency within3dB. As the magnetic flux leakage testing bad environment, thearticle use ultrasonic current displacement sensor to measure the value betweenMFL detection probe shoots and the steel pipes. Combined with the contactprobe boots with steel pipe, by measuring the detection shoe ends displacementvalues, using the linear fitting can get every point position of the probe lift offvalue for the realization of magnetic flux leakage testing, providing the basis forcorrection signal compensation.Added the ultrasonic displacement sensor, detection system is changed, it needto increase the ultrasonic displacement measurement signal data, at the same timeit need to ensure the signal of magnetic flux leakage testing and ultrasonic displace--ment sensor signal temporal consistency. Based on MFL signal compensation canimprove the MFL signal constituency,it can improve the MFL equipment of falsenegative rate and false alarm rate, enhance properties of MFL testing equipment,provide the basis of boots for the further development of non-contact MFL testing.