Quantitative Research on Signal of Pipeline Coating Defect Detection Based on HHT

Coating is a very important way to ensure the integrity of the pipeline. However, due to environmental or external factors, the coating will has some defects such as peeling defects, holes and so on. This paper is concentrated on axial stripping defects and holes of buried pipeline coated with anti-corrosion coating, using ultrasonic guided wave detection technology to obtain the coating detection signal to do the study of quantification, it provides a feasible method to study the level quantitative description of the anticorrosive layer peeling defects.Doing time-frequency analysis to the operating status of the coating, we will have a conclusion that when the coating has peeling defects, the waveform of the detection signal will has a nonlinear characteristic signal. According to the analysis of time-frequency distribution, we can find out that when the signal has nonlinear characteristic signal, the time-frequency distribution will have a "concave" type frequency distribution, it is the basis to judge the junction of the coating peeling defects. According to the judgment, and obtain the relative length of the coating stripping defect, it will finally obtain the degree of damage caused by peeling defects.Therefore, this paper is a post-treatment method for pipeline coating detection, providing feasible and effective signal processing methods and quantitative research methods for the engineering application of the detection technology of non-linear ultrasonic pipeline coating peeling defects.