Michael Lowe, PhD, worked in engineering consultancy from 1979 to 1989. He then joined Imperial College and is Head of the Department of Mechanical Engineering. His research is in ultrasound NDE, with specialist interests in guided waves, scattering, and materials characterisation. He has published about 300 papers on these topics.
Inspection and monitoring of pipelines for defects using ultrasonic guided waves
Guided Wave Testing (GWT) of pipelines was developed in the 1990s and commercialised 20 years ago, and it is now well established in use in the oil and gas and chemical industries. Its main application is the inspection for internal or external corrosion of pipe walls, exploiting waves that are guided along the pipeline. This is done using a transducer ring that is placed non-intrusively on the outside of the pipe while the test is done and the pipe remains live. This provides a very rapid test while achieving 100% coverage of the material volume. The principal use of GWT is as a screening tool: a rapid GWT inspection is used to detect the presence of significant reflectors which are then examined locally in detail using conventional methods of NDE.
An alternative approach, which is gaining increasing interest, is to use permanently-installed sensors. These can gather data autonomously and so monitor the pipelines to detect the onset and growth of any defects. This is particularly valuable at locations that are safety-critical or where repeat access for inspection is difficult, and has the potential to gather rich and informative data.
The presentation will cover the physics of the GWT method and the key developments that brought it into deployment in industry, including some practical examples of its use both for inspection and monitoring. It will then show some current developments that are in progress for monitoring, and suggest some possible future opportunities that these may bring for the nuclear industry.