Fouling Detection Based on Analysis of Ultrasonic Guided Waves Using Wavelet Transform

Fouling detection is a relevant problem for chemical, oil, food and pharmaceutical industries. Fouling consists of the deposition of heavy organic materials and other dissolved solids or in suspension in fluid transport system. The ultrasonic guided waves present specific characteristics and have demonstrated good results in detection of flaws in pipelines. In this paper, the application of wavelet transform to analyze ultrasonic signals in order to detect fouling in pipelines is presented. A platform of tests has been used to emulate the fouling problem. The pipelines were used as a medium to guide ultrasonic waves and weekly measurements were used to observe the fouling process. The Daubechies 4 wavelet was applied to each measurement set. The results reveal that the variations of the energy-spectrum of the wavelet detail coefficients may provide an appropriate way to detect fouling, since it was observed that the increase of the fouling causes a notable reduction in the energy values.