51315-5750-Ultrasonic Computerized Tomography for Continuous Monitoring of Corrosion and Erosion Damage in Pipe

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Product Number: 51315-5750-SG

ISBN: 5750 2015 CP

Author: Francesco Simonetti

Publication Date: 2015

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Throughout the oil and gas industry corrosion and erosion damage monitoring plays a central role in managing asset integrity. This paper introduces a novel technology for continuous monitoring of wall-loss rates in pipelines. A pair of permanently installed ring arrays of ultrasonic transducers encircles the pipe and delimits the section to be monitored. The arrays excite and receive guided ultrasonic waves that travel inside the pipe wall and insonify the entire pipe section. The received signals are then processed by advanced tomographic algorithms to produce a point-by-point map of wall thickness loss between the arrays. The algorithms are designed to detect changes between two material states of the pipe and use differential measurements to eliminate time-independent experimental uncertainties. As a result wall loss can be estimated with accuracy beyond the pipe manufacturing tolerances. Moreover a strategy that combines a robust temperature compensation scheme with the intrinsic thermal stability of electromagnetic acoustic transducers (EMATs) is used to address signal instabilities caused by typical thermal fluctuations experienced in field applications. Full-scale experiments are presented demonstrating maximum-depth estimation accuracy better that 0.5% of wall thickness with excellent thermal stability up to 175° C. Performance dependence on array separation distance and defect morphology is also discussed.