Monitoring of high temperature steel pipes by ultrasonic waveguide solutions

Power plant operators have to increase the operating temperature to meet the CO2 reduction demands. The safety risk of such piping systems is of overriding importance. Material or structural failure leads to considerable property damage and possibly even personal injury must be expected. Moreover, there is a considerable economic risk in case of structural failure regarding the availability of the plant. Online ultrasonic monitoring techniques are well suited to detect corrosion damages like cracks or wall reductions. Guided waves propagate through the medium to be investigated and interact with the defects depending on their size (depth, length and width). Different frequencies and wave modes were analyzed to optimize the transmitting signal to the monitoring task. Challenging tasks were the application on hot pipes including temperatures up to 650 degree, the long term stability of the measurement systems especially of the sensors and the test under operating conditions. The results show the feasibility of permanent and process controlled condition monitoring for industrial application areas. The proposed solution meets all legal needs. The next step will be the commercialization of the monitoring system and the extension of the application areas e.g. to pipelines and refinery applications.