Defect characterisation from limited view pipeline radiography

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Title: Defect characterisation from limited view pipeline radiography
Author(s): Haith, MI
Huthwaite, P
Lowe, MJS
Item Type: Journal Article
Abstract: This work presents a method of characterising pipeline defects using a small number of radiographs taken at different angles around the pipe. The method relies on knowledge of the setup geometry and use of multiple images, and does not require calibration objects to be included in the setup. It is aimed at use in situations where access is difficult such as in subsea pipeline inspections. Given a set of radiographs, a background subtraction method is used to extract defects in the images. Using a ray tracing algorithm and knowledge of the experimental setup, the range of possible locations of the defect in 3D space is then calculated. Constraints are applied on potential defect shapes and positions to further refine the defect range. The method is tested on simulated and experimental flat bottomed hole defects and simulated corrosion patch defects with lateral and axial sizes ranging from 12.5 to 33.8 mm and thickness between 3 mm and 16 mm. Results demonstrate a good, consistent ability to calculate lateral and axial defect dimensions to within ±3 mm of the true size. Defect thickness calculations are more difficult and as such errors are more significant. In most cases defect thickness is calculated to within 4 mm of the actual value, often closer. Errors in thickness are due to overestimation, meaning the calculation could be used to place a maximum limit on potential defect size rather than as an actual estimate of the thickness. This would still be useful, for example in deciding whether a defect requires further investigation.
Publication Date: 18-Dec-2016
Date of Acceptance: 16-Dec-2016
URI: http://hdl.handle.net/10044/1/45748
DOI: https://dx.doi.org/10.1016/j.ndteint.2016.12.007
ISSN: 0963-8695
Publisher: ELSEVIER
Start Page: 186
End Page: 198
Journal / Book Title: NDT & E INTERNATIONAL
Volume: 86
Copyright Statement: © 2016 Elsevier Ltd. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
Sponsor/Funder: Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
NDE Research Association Ltd
Engineering & Physical Science Research Council (EPSRC)
Funder's Grant Number: EP/F017332/1
EP/L022125/1
N/A
EP/020207/1
Keywords: Science & Technology
Technology
Materials Science, Characterization & Testing
Materials Science
Digital radiography
Image processing
Defect characterisation
Pipeline radiography
Acoustics
09 Engineering
Publication Status: Published
Appears in Collections:Faculty of Engineering
Mechanical Engineering
Faculty of Natural Sciences



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