| 摘要 |
PURPOSE:To monitor the change of quality without destruction by making ultrasonic waves of a longitudinal wave and two transversal waves orthogonal to each other incident on a monitor object in the normal state and comparing a parameter obtained by a specific formula with the current parameter. CONSTITUTION:A ratio of the longitudinal wave to the average value of two transversal waves is preliminarily calculated as a parameter RO=CL/CT (CL: longitudinal wave speed CT: the average value of two transversal wave speed). A ratio of the longitudinal wave to the difference between two transversal waves is calculated as a parameter phi0=DELTACT/CT (DELTACT: difference between two transversal waves) which compensates the parameter RO. Respective propagation time differences of ultrasonic waves are always measured in the actual operation state of a power plant to calculate parameters R and phi, and these parameters are compared with parameters RO and phiO preliminarily obtained in the normal state. If current parameters R and phi are considerably deviated from preliminari ly calculated parameters RO and phiO, the change of quality is recognized and is reported to a worker by a display means. |
