Ultrasonic Monitoring of Flaw Growth at 600 ̊c (1110 ̊f) in an Operational Power Plant

Flaw growth monitoring at operational temperatures in high-temperature plants has long been recognised as a highly desirable inspection goal, particularly in regard to effective outage management and lifetime extension of existing plants, and increasing the reliability of future plants through the incorporation of active monitoring systems. However, despite considerable efforts in the area of high temperature inspection, practicable solutions for implementing long-term continuous flaw growth monitoring in operational power plants have proved elusive. KANDE International and E.ON have worked together over a number of years to develop a viable means of performing long-term monitoring of known flaws in operational fossil-fuel power plant components, where operating temperatures can be as high as 600°C (1110°F), and we have previously reported on the development and laboratory testing of permanently installed high temperature ultrasonic probes and associated testing techniques. In this paper we report on the progress made to date in a new study that is investigating the wider problems associated with performing remote monitoring of real flaws in a main steam line in an operational plant. We discuss the approaches used to address a range of issues including: the permanent attachment of probes close to known flaws; designing an instrumentation system capable of recording data and transmitting it to an off-site location with minimal operator intervention; and the development of software tools to display and analyse the resulting data so that flaw growth can be identified and measured. We comment on the lessons learned to date and on how the experience gained will influence the future development of the technology.