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|NDT.net Issue - 2016-11 - NEWS ||NDT.net Issue: 2016-11|
Publication: e-Journal of Nondestructive Testing (NDT) ISSN 1435-4934 (NDT.net Journal)
Non Destructive Testing of defects in oil and gas pipelinesBrunel University36, Uxbridge, United Kingdom
This research is being carried out in collaboration with TWI and is focussed on the Long Range Ultrasonic Testing of pipelines. This non-destructive technique aims to locate defects in pipelines by sending an acoustic wave down the walls of the pipe and then detecting reflections scattered by a crack or region of corrosion in the pipe walls.
LRUT is suitable for testing lengths of pipe of over 70 m in length if the pipe is uncoated and is not buried. However, it is common for pipe to be buried in materials such as soil or sand. Moreover, viscoelastic coatings may also be applied to the outside of the pipe in order to protect the walls from corrosion. Both scenarios mean that the energy in the acoustic wave sent down the pipe either attenuates as it travels through the viscoelastic coating and/or leaks out into the surrounding medium. This can significantly lower the range of LRUT. The focus of this work is on developing computational models to understand the mechanisms of attenuation and energy leakage in order to improve LRUT under these difficult conditions and increase testing range.
Example of a pipe with coating.
The wave is generated in this example using the commercial LRUT equipment Teletest.