Abstract
Pipe wall thickness loss caused by corrosion and erosion is a significant safety concern in industry. In the field and on plant the detrimental effects of corrosion are often evaluated using ultrasonic thickness measurements. Due to difficult field conditions, changes in setup and a range of other factors these measurements are usually only precise to within fractions of a millimetre. However advances in ultrasonic technology as well as the possibility of permanently installing them at reasonable economic cost have seen an increase in precision of several orders of magnitude. This substantial gain in precision allows the evaluation of very small wall loss rates in a matter of hours, which in turn can be used to evaluate and adjust corrosion mitigation strategies. To assess the potential of ultrasonic monitoring, a state of the art permanently installed ultrasonic sensor setup is evaluated in this paper using an electrolytic corrosion cell, which allows us to benchmark the performance of the sensor while controlling conditions inside the cell. The ultrasonic thickness estimates are compared to electrochemical measurements under a range of potentials, currents, pH levels and various electrolytes to investigate the ranges of potential application. The results of the investigation show that below 100 nanometre precision is achievable using the ultrasonic sensor in laboratory conditions.
