High temperature ultrasonic measurements of plant and components for defect detection and monitoring

There are many instances where components and plant operate at elevated temperatures such as turbines, high temperature processing pipework, power generation boilers and reactors. Currently, most non-destructive testing (NDT) is carried out at lower or ambient temperature, necessitating at least partial shut-down of the process. Planned outage of plant is costly but the cost of unplanned outage due to catastrophic failure can run to millions of pounds, and can have extremely serious consequences for the safety of personnel and the public. In addition, some plant contains areas that are extremely difficult to access even during an outage meaning that the only viable approach is to use permanently installed monitoring. We propose devices and concepts to enable high temperature monitoring and inspection where it is currently impossible. This is stimulated not only by the industrial imperative, but also by major advances in knowledge and understanding of high temperature piezoelectric materials, in thick film and thin film form, operating at temperatures up to 800C. The attraction in developing high temperature sensors from these materials is that they can be robust, inexpensive and permanently installed on plant. In a novel hybrid system concept, not previously applied to high temperature inspection, we will combine these with improved non-contact ultrasonic generation techniques.