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Ultrasonic Guided Wave Tomography for Wall Thickness Mapping in Pipes

Willey, Carson Landis
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1460729589

Abstract Details

2016, PhD, University of Cincinnati, Engineering and Applied Science: Engineering Mechanics.
Corrosion and erosion damage pose fundamental challenges to operation of oil and gas infrastructure. In order to manage the life of critical assets, plant operators must implement inspection programs aimed at assessing the severity of wall thickness loss (WTL) in pipelines, vessels, and other structures. Maximum defect depth determines the residual life of these structures and therefore represents one of the key parameters for robust damage mitigation strategies. In this context, continuous monitoring with permanently installed sensors has attracted significant interest and currently is the subject of extensive research worldwide. Among the different monitoring approaches being considered, significant promise is offered by the combination of guided ultrasonic wave technology with the principles of model based inversion under the paradigm of what is now referred to as guided wave tomography (GWT). Guided waves are attractive because they propagate inside the wall of a structure over a large distance. This can yield significant advantages over conventional pulse-echo thickness gage sensors that provide insufficient area coverage – typically limited to the sensor footprint. While significant progress has been made in the application of GWT to plate-like structures, extension of these methods to pipes poses a number of fundamental challenges that have prevented the development of sensitive GWT methods. This thesis focuses on these challenges to address the complex guided wave propagation in pipes and to account for parametric uncertainties that are known to affect model based inversion and which are unavoidable in real field applications. The main contribution of this work is the first demonstration of a sensitive GWT method for accurately mapping the depth of defects in pipes. This is achieved by introducing a novel forward model that can extract information related to damage from the complex waveforms measured by pairs of guided wave transducers mounted on the pipe. An inversion method that iteratively uses the forward model is then developed to form a map of wall thickness for the entire pipe section comprised between two ring arrays of ultrasonic transducers that encircle the pipe. It is shown that time independent parametric uncertainties relative to the pipe manufacturing tolerances, transducers position, and ultrasonic properties of the material of the pipe can be minimized through a differential approach that is aimed at determining the change in state of the pipe relative to a reference condition. On the other hand, time dependent parametric uncertainties, such as those caused by temperature variations, can be addressed by exploiting the spatial diversity of array measurements and the non-contact nature of electromagnetic acoustic transducers (EMATs). The range of possible applications of GWT to pipes is investigated through theoretical and numerical studies aimed at developing an understanding of how the performance of GWT varies depending on damage morphology, pipe geometry, and array configuration.
Francesco Simonetti, Ph.D. (Committee Chair)
Jongguen Lee, Ph.D. (Committee Member)
Guirong Liu, Ph.D. (Committee Member)
T. Douglas Mast, Ph.D. (Committee Member)
144 p.
Acoustics
Tomography; Ray theory; Diffraction; Guided waves

Recommended Citations

Citations

  • Willey, C. L. (2016). Ultrasonic Guided Wave Tomography for Wall Thickness Mapping in Pipes [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1460729589

    APA Style (7th edition)

  • Willey, Carson. Ultrasonic Guided Wave Tomography for Wall Thickness Mapping in Pipes. 2016. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1460729589.

    MLA Style (8th edition)

  • Willey, Carson. "Ultrasonic Guided Wave Tomography for Wall Thickness Mapping in Pipes." Doctoral dissertation, University of Cincinnati, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1460729589

    Chicago Manual of Style (17th edition)

ucin1460729589
371
© 2016, some rights reserved.Creative Commons License Ultrasonic Guided Wave Tomography for Wall Thickness Mapping in Pipes by Carson Landis Willey is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by University of Cincinnati and OhioLINK.