Preliminary assessment of the feasibility of field evaluation of heat exchanger tube structure using ultrasonic guided wave with exterior approach

The integrity of heat exchanger (HE) tubes is essential for power plant safety and efficiency. Numerous tube assessment techniques have been proposed, including eddy current inspection and the guided wave method. However, they mainly evaluate from the inside of the tubes. Hence, when the interior region of a tube wall is not accessible, inspection is difficult. To overcome this issue, a new guided wave device is fabricated that inspects from the exterior of the heat exchanger tubes. Using this device, a few sample heat exchanger tubes are selected and inspected in a field evaluation during an overhaul period. Furthermore, the feasibility of the device is evaluated. This new approach is expected to contribute to the efficient evaluation of heat exchanger tubes.