[10A4] Assessment of pipe wall corrosion using high-order ultrasonic guided waves
D Cirtautas, V Samaitis and L Mažeika
Kaunas University of Technology, Lithuania
Corrosion detection in pipes is critical to the nuclear plant, oil, gas and other chemical industries. Hidden defects could lead to dangerous accidents such as leakage of toxic materials causing extreme environmental damage and economic consequences. Ultrasonic testing stands out among the classic corrosion detection techniques as the direct and non-intrusive method that evaluates corrosion rates. However, currently existing ultrasonic methods suffer from inspection time, accuracy and sensitivity trade-off, meaning that either the accurate localised inspection or rough long-range screening is available for corrosion assessment. As a result, localised inspections can only detect widely distributed corrosion with a-priori known locations, while the long-range systems are dedicated for detection of randomly distributed large flaws. In this research, a medium range corrosion screening approach based on generation of high-order guided waves is proposed. First, the selection of mode types and means of their isolated excitation is analysed with the support of finite element modelling. The sensitivity of high-order modes to the pipe wall thickness loss and the influence of energy leakage to surrounding media is then addressed. Finally, interaction of high-order modes with various corrosion related artificial defects is investigated and verified. The research concludes with advantages and limitations of proposed screening approach.
