Clough, Matthew (2016) Defect screening of pipelines using circumferential guided waves. EngD thesis, University of Warwick.

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Abstract

A system for the shear horizontal guided wave screening of pipelines is developed and optimised. The system is considered in terms of the circumferential shear horizontal guided wave behaviour as opposed to the majority of other studies that approximate the structure of an unwrapped pipe as a plate. This allows for consideration of the effect of a defect on both the lowest order symmetric and antisymmetric modes. The assessment of the guided wave interaction with a corrosion patch defect is carried out for a basic defect from which the axial sizing can be determined from encoded scans of the sample and amplitude changes. The circumferential positioning capabilities can be found using the effect seen on different modes and the presence of reflections. The behaviour of the two lowest order shear horizontal modes when incident on a defect above and below the cut off thickness of the lowest order antisymmetric mode can be seen in the experimental measurements and visualised through finite element modelling.

Once the behaviour of the modes when they interact with different depths of a defect is understood, the technique is expanded to a real corrosion patch of known dimensions. It is extended to more complex samples with multiple, varied positioned corrosion patches and blind trial situations where the geometry and depth of defects is unknown. Although the size and depth of these defects is unknown, the knowledge of the interaction of the waves with the other defects can be used to estimate the defect size and depth. The calculation of the remaining wall thickness in the current iteration of the system is limited to a broad range, unless there is prior knowledge of the defect geometry. This is because the defect geometry is shown to have a large effect on the arrival time of the through transmitted waves. Consideration is given to the effect of welds on a signal and the differences between calibration defects and real corrosion patch style defects.

The system has been tested further in extended blind trials and proved effective as a screening tool for the detection of corrosion patch style defects, with detection capabilities dependent on the axial size and depth of the defect.

Item Type:	Thesis (EngD)
Subjects:	T Technology > TA Engineering (General). Civil engineering (General)
Library of Congress Subject Headings (LCSH):	Nondestructive testing, Pipelines -- Corrosion, Pipelines -- Inspection, Electromagnetic testing, Ultrasonic testing
Official Date:	September 2016
Dates:	Date Event September 2016 Submitted
Institution:	University of Warwick
Theses Department:	Department of Physics
Thesis Type:	EngD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Dixon, Steve M. ; Fleming, Matthew
Sponsors:	UK Research Centre in Nondestructive Evaluation ; Sonomatic Ltd.
Format of File:	pdf
Extent:	xviii, 198 leaves : illustrations, charts
Language:	eng

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