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Condition assessment of PVC water mains using phased array ultrasonic testing


Start: 01-11-2018
End: 01-11-2022


This project is funded by and executed in collaboration with Strukton Rail


The project is funded by and is in collaboration with water companies i.e.,  Acquaint B.V.,  PWN, Vitens, Wavin, Evides, and Brabant Water along with Wetsus, the European center of excellence for sustainable water technology


Richard Loendersloot, Tiedo Tinga, Dr. ir. D. Yntema


The Dutch water distribution network stretches over a length of 120,000 km out of which, half of its length is made of Polyvinyl Chloride (PVC). Water mains are degrading over time and its current state is mostly unknown. This brings rise to situations where assets in good condition are replaced prematurely, while other assets are not replaced on time. Thus, they fail before expectation time which increases repair and material costs. Water companies incur costs over several million euros to keep their water pipelines operational. Therefore, an inspection of water mains is crucial, in order to repair and replace them before they fail.

Inspection techniques making use of ultrasonic waves are found to be promising to detect and characterize defects in materials as they belong to the category of non-destructive testing. Polymers like PVC are very difficult to assess using conventional ultrasonic techniques as they have low sensitivities towards detecting its degradation. The ultrasonic technique of wave mixing has proven to detect the change in material properties of PVC with time. It makes use of two acoustic waves that interact at an angle to generate a third acoustic wave when certain resonance conditions are satisfied. But there are chances of misalignment of the transducers with respect to PVC such that, the generated wave cannot be recorded at its maximum amplitude.

This project aims in making use of actuator and receiver arrays to steer and focus the sound beam at desired angles using time delays. The arrays can be used to implement the wave mixing technique to inspect PVC in a much efficient way. The physical movement of the probe is not necessary and therefore, it's positioning with respect to the sample will not be hampered. Therefore, the chances of misalignment errors are highly reduced. This method can also provide information about the shapes and sizes of the interaction volume in the material and thus, the distribution of mixed frequencies within this volume.