Temperature Compensation for Ultrasound Corrosion Monitoring

Abstract Non-intrusive ultrasound monitoring of pipe walls enables the detection of wall thinning with micrometre accuracy. This is achieved by measuring the time of acoustic reflection between the inner and outer wall surfaces. A fundamental challenge is that the propagation speed of the ultrasonic wave has a weak dependency on the material temperature, which could vary with ambient temperature and pipe flow temperature. Compensating for temperature fluctuations is achieved today by probing the temperature combined with apriori assumptions about the temperature coefficient for the given material. The authors of this paper propose a method for optimizing the temperature compensation coefficient by de-correlating the pipe wall thickness measurements and the temperature. By this, significant improvements are made to the repeatability of thickness measurements through temperature variations. Furthermore, it has been demonstrated that accurate temperature compensation can be achieved solely using ultrasound data, eliminating the need for separate temperature probes. This practical approach is particularly beneficial for sensors designed for high and ultra-high temperatures, making the process more efficient and cost-effective. The methods presented are supported by synthetic, laboratory and real case stories.