RESIDUAL AVERAGE THICKNESS ESTIMATION METHOD BASED ON ESTIMATION OF AVERAGE CORROSION DEPTH IN GROUND-LEVEL CORROSION IMPAIRMENT PART

摘要

PROBLEM TO BE SOLVED: To efficiently estimate residual average thickness by easily implementing measurement without removing swelling coating or caulking.SOLUTION: A flaw detection waveform is computed from vortex flaw detection data measured in a nondestructive manner by scanning a ground-level portion of a steel material on the ground in a direction orthogonal to a direction of extension by means of a vortex flaw detection sensor. A stochastic density function approximate to the flaw detection waveform is computed by nonlinear regression analysis using a Gaussian function. The stochastic density function of standard regular distribution is compared with the Gaussian function to estimate parameters for a maximum voltage amplitude of the Gaussian function, standard deviation of voltage amplitudes, a position of the maximum amplitude and an initial value of amplitudes. While assuming accumulation of the stochastic density function as a defect sectional area, conversion is performed for modeling the defect sectional area from a stochastic density curve of the stochastic density function. A virtual corrosion width obtained from the formed model is calculated on the basis of the standard deviation of voltage amplitudes, and average corrosion depth is estimated from the corrected virtual corrosion width and the defect sectional area.