Pipeline Integrity Monitoring by Synthesizing the Foremost Technologies of Ultrasonic Guided Waves and Impedance Method and the Innovative Flexural Transducer Arrays

Description

In-service pipelines are prone to defects due to aging, external impacts, and corrosion caused by hazardous operating environments. Leaky or ruptured pipes may result in serious pollution to the environment, causing huge economic loss and even human casualties. Maintaining the integrity of pipelines is a prime and immediate concern in nearly all cities worldwide. Much research effort has been spent on finding robust methods for monitoring the health of different parts of the pipe. Among them, guided waves and impedance method are two promising techniques that can be used for inspecting the pipe body and pipe connecting parts/joints respectively. However, both of them suffer from many deficiencies. First, the two costly transduction systems must be used separately for the two techniques. There is currently no synthesis for the two techniques. Second, a weak signal is received due to the difficulty in mounting the transducers on the curvature of the pipe. Third, the emission of guided waves with just a single mode, which is a typical practice currently used in pipe body inspection, can only detect defects at a particular geometric orientation. Fourth, the accuracy in defect detection is lower because of a lack of optimization of the techniques used. Fifth, the received signal is always overwhelmed by interference.In this project, the research team proposes several novel techniques to overcome these deficiencies. First, to reduce instrumentation costs, the researchers will design a transduction system that will be used for both the guided waves and the impedance method. Guided waves monitor the existence of defects in the pipe body. The impedance method evaluates the change of structural impedance caused by defective connecting parts or joints. Second, the researchers will design flexible transducers to maintain close contact with the inspected pipe. Third, a mixture of selected guided wave modes will be emitted to monitor defects with different geometric orientations. Fourth, optimization will be applied to select the proper parameters for guided waves and the impedance method. Fifth, through experiments, vital influence factors of working conditions, such as the pipe operating environment and the content carried by the pipe, will be investigated to understand their characteristics and degrees of influence. The advanced signal analyses, including blind deconvolution and the improved Hilbert-Huang transform, will be employed to minimize such interference so that the purified features can be obtained for easier defect monitoring. In summary, a comprehensive health monitoring system will be developed to maintain the integrity of pipelines.