直流電位差計測に基づく円管の一様減肉評価

抄録

In this study, a simple method to evaluate the uniform pipe wall thinning by using the DC potential difference method was examined. Four probes are placed on the outer surface of the pipe of outer diameter D. The thicknesses of the pipe before and after thinning are represented as t₀ and t, respectively. The constant DC current is applied to the pipe through two outer probes, and the potential difference between two inner probes is measured. The potential differences measured at the pipe of thickness t₀ and t are represented as V₀ and V₁, respectively. The thickness ratio t/t₀ is evaluated from the value of V₁/V₀. Three-dimensional finite element method was used to analyze the relation between thickness and potential difference for various cases. As a result, it was shown that the calibration relation for the case of D/t₀ is 10 or more is almost the same as that for the flat plate. Then a simple method to evaluate the thickness of the pipe having a diameter D/t₀ ≥ 10 using a calibration relation of flat plate was proposed, and its validity was shown by experiments.