Pipeline structures are susceptible to cracks, corrosion, and other ageing defects. If left undetected, these forms of damage can lead to the failure of the pipeline system, which may have catastrophic consequences. Most current forms of health monitoring for pipeline systems involve non-destructive evaluation (NDE) techniques. These techniques require sophisticated instruments and direct access to the structure, which is not always possible for civil pipeline applications. This research proposes the use of macro-fibre composite (MFC) transducers for real-time structural health monitoring in pipeline systems. In particular, we propose the coupled implementation of impedance-based and Lamb wave-based methods that are simultaneously used to accurately determine the health of a pipeline network. The self-sensing impedance methods are used to detect structural damage occurring at pipeline connection joints, while the Lamb wave propagation measurements identify cracks and corrosion along the surface and through the wall thickness of the pipe structure. Both methods utilize the same MFC active sensors, which are flexible, durable, relatively inexpensive, and can be permanently bonded to the surface of a pipe during installation. Therefore, measurements for damage identification can be performed at any time, even while the system is in operation. Based on the success of this study, guidelines are outlined for the full-scale development of a low-cost, active-sensing-based SHM system suitable for pipeline applications. Published in 2007 by John Wiley & Sons, Ltd.

The United States economy is heavily dependent upon a vast network of pipeline systems to transport and distribute the nation's energy resources. As this network of pipelines continues to age, monitoring and maintaining its structural integrity remains essential to the nation's energy interests. Numerous pipeline accidents over the past several years have resulted in hundreds of fatalities and billions of dollars in property damages. These accidents show that the current monitoring methods are not sufficient and leave a considerable margin for improvement. To avoid such catastrophes, more thorough methods are needed.As a solution, the research of this thesis proposes a structural health monitoring (SHM) system for pipeline networks. By implementing a SHM system with pipelines, their structural integrity can be continuously monitored, reducing the overall risks and costs associated with current methods. The proposed SHM system relies upon the deployment of macro-fiber composite (MFC) patches for the sensor array. Because MFC patches are flexible and resilient, they can be permanently mounted to the curved surface of a pipeline's main body. From this location, the MFC patches are used to monitor the structural integrity of the entire pipeline.Two damage detection techniques, guided wave and impedance methods, were implemented as part of the proposed SHM system. However, both techniques utilize the same MFC patches. This dual use of the MFC patches enables the proposed SHM system to require only a single sensor array. The presented Lamb wave methods demonstrated the ability to correctly identify and locate the presence of damage in the main body of the pipeline system, including simulated cracks and actual corrosion damage. The presented impedance methods demonstrated the ability to correctly identify and locate the presence of damage in the flanged joints of the pipeline system, including the loosening of bolts on the flanges. In addition to damage to the actual pipeline itself, the proposed methods were used to demonstrate the capability of detecting deposits inside of pipelines. Monitoring these deposits can prevent clogging and other hazardous situations.Finally, suggestions are made regarding future research issues which are needed to advance this research. Because the research of this thesis has only demonstrated the feasibility of the techniques for such a SHM system, these issues require attention before any commercial applications can be realized.

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