Research On The Detection Of Bottom Surface Defects Of Atmospheric Pressure Vessels Based On Eddy Current Sensor System

As a common equipment for the production,storage and transportation of chemical products,atmospheric pressure vessels have a wide range of application requirements.After long-term use,on the tank bottom of atmospheric pressure vessels of hazardous chemical products are prone to structural defects such as corrosion reduction and electrochemical corrosion,which greatly increases the accident risk of the chemical industry.Therefore,it is of great significance to carry out comprehensive defect detection on the tank bottom of chemical atmospheric pressure vessels.Eddy current testing is a detection technology which is non-contact,non-radiative,non-coupling agent,low detection cost and fast.According to the detection requirements on the bottom surface of atmospheric pressure vessels,this method based on eddy current testing technology is researched in this paper.A double air core coil is used as an eddy current sensor to detect the eddy current induction signal on the bottom surface of atmospheric pressure vessels under multifrequency sinusoidal excitation.The phase gradient is selected as the characters of the detection signal,and the feature is calculated in a two-dimensional space.Finite element simulation analysis of several parameters affecting eddy current testing is also conducted.The portable experimental equipment is implemented,a set of eddy current sensor system is built,and a two-dimensional planar scanning detection method is proposed based on the characteristic quantity of the phase gradient,performing eddy current testing and defect identification research on the aluminum plate sample,iron plate sample,and atmospheric pressure vessels bottom sample.Studies have shown that using the phase gradient as the characteristic quantity of the detection signal,the method of performing a two-dimensional planar scanning detection on the bottom surface of atmospheric pressure vessels through the eddy current sensor system can accurately identify the crack defect of atmospheric pressure vessels bottom sample while effectively suppressing the lift-off noise.And it is obvious about the visual inspection effect of the phase gradient graphs.