Study on pipeline corrosion monitoring based on piezoelectric active time reversal method

Pipeline corrosion, especially inner wall corrosion, will cause serious safety accidents. It is important to monitor the corrosion inside the pipeline to reduce the potential risk. Considering the thickness of the pipe wall will become thinner due to the corrosion which will cause the attenuation of the propagated ultrasonic signal energy. Based on this, a novel method for real-time monitoring of pipeline inner wall corrosion using piezoelectric active sensing technology combined with time reversal method is proposed. Two PZT patches are bonded on the outer surface of the pipe as an actuator and a sensor to generate and receive ultrasonic signals propagating in the pipeline wall, respectively. With the time reversal method, the received response signal is reversed in the time domain and then re-emitted as an excitation signal again. Then the time reversal focused signal which represents the signal energy is obtained. By analyzing the received signal energy, that is the focused signal peak, the corrosion state in the inner wall of pipeline can be judged. Experiments are performed to verify the proposed method. In the experiments, the electrochemical corrosion is used to generate the occurrence and evolution of erosion inside the pipeline. Eight different corrosion states of three sample pipelines were studied at different corrosion time. The experimental results show that the peak amplitude of the focused signal decreases with the increase of corrosion time with good repeatability. The method is feasible in pipeline corrosion monitoring, especially in monitoring of the early pipeline corrosion, which has a good application prospect.