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Experimental results of guided wave travel time tomography

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Author: Volker, A.W.F. · Mast, A. · Bloom, J.G.P.
Type:article
Date:2009
Publisher: AIP
Institution: TNO Industrie en Techniek
Source:36th Annual Review of Progress in Quantitative Nondestructive Evaluation, QNDE 2009, 26-31 July 2009, Kingston, RI, USA, 1211, 2052-2059
series:
AIP Conference Proceedings
Identifier: 347452
ISBN: 9780735407480
Keywords: Electronics · Corrosion monitoring · Dispersion · Guided wave · Inversion · Parameterization · Tomography · Travel time · Ultrasonic

Abstract

Corrosion is one of the industries major issues regarding the integrity of assets. Currently inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. Both economical and social requirements are pushing the industry to even higher levels of availability, reliability and safety of installations. The concept of predictive maintenance using permanent sensors that monitor the integrity of an installation is an interesting addition to the current method of periodic inspections reducing uncertainty and extending inspection intervals. Guided wave travel time tomography is a promising method to monitor the wall thickness quantitatively over large areas. Obviously the robustness and reliability of such a monitoring system is of paramount importance. Laboratory experiments have been carried out on a 10″ pipe with a nominal wall thickness of 8 mm. Multiple, inline defects have been created with a realistic morphology. The depth of the defects was increased stepwise from 0.5 mm to 2 mm. Additionally the influences of the presence of liquid inside the pipe and surface roughness have been evaluated as well. Experimental results show that this method is capable of providing quantitative wall thickness information over a distance of 4 meter, with a sufficient accuracy such that results can be used for trending. The method has no problems imaging multiple defects.