Ultrasonic transducer for high temperature thickness monitoring

Abstract

Refineries typically undergo 30–60 days of programmed shutdowns every 4 to 6 years to assess the integrity of infrastructure not accessible during service. So far, the literature demonstrated the feasibility of using ultrasonic probes for continuous long-term monitoring up to 350°C. However, when the temperature keeps rising, an air- or water-cooling system is required or a long delay line is used to move the probe away from the heat source. Providing a real time monitoring solution for the most critical components operating at high temperature would increase safety and reduce the maintenance burden. In this talk, an ultrasonic probe operating completely immersed inside a 600°C (1112°F) environment for extended periods of time is presented. The design of the transducer will be discussed. Its small footprint enables it to be mounted at several critical and difficult to access locations. In order to validate performances transducers were mounted on plates and pipes of different materials and thicknesses and the assembly was put inside a furnace. The results of long-term stability at 600°C, the consistency of the measurements over a temperature range from 20°C to 600°C, and the robustness during aggressive thermal cycling will be presented.