| 摘要 |
PROBLEM TO BE SOLVED: To provide a thin steel pipe thickness measurement method reliably determining a time intervalΔt of an echo and performing substantially continuous thickness measurement over the entire length in the longitudinal direction of the tube, in place of a conventional method determining the time interval of an echo by echo fitting processing. SOLUTION: The thickness measurement method includes the steps of: performing frequency analysis of an echo detected by an optical interferometer 2a; extracting a peak frequency having the maximum amplitude intensity of the echo after removing high-frequency noise components from spectral distribution obtained by wave number analysis; determining the time interval the echo from the peak frequency; and calculating the thickness on the basis of an expression of thickness=(1/2)×v×Δt×a, where v is ultrasonic wave propagation velocity in steel,Δt is echo time interval=t<SB>n</SB>-t<SB>n-1</SB>(t<SB>n</SB>is detection time of the n-th echo, t<SB>n-1</SB>is detection time of (n-1)-th echo), and a is geometric correction value of an ultrasonic wave propagation route. COPYRIGHT: (C)2010,JPO&INPIT
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