THE STUDY OF THE EDDY CURRENT DISTRIBUTION AREA INDUCED BY SURFACE EDDY CURRENT PROBE IN MAIN GAS PIPELINE METAL HOT-DIP GALVANIZING UNITS

The distribution area of eddy currents induced on metallic surfaces by the alternating magnetic field of surface eddy current probes (ECPs) is investigated. Analytical calculations reveal that the effective eddy current distribution excited by surface ECPs forms a circular region, with its radius determined by the core diameter of the surface ECP. Various approaches for estimating the spatial extent of eddy current distribution induced by surface ECPs are examined. The study indicates that more accurate results are achieved by determining the boundary of the eddy current distribution area through calculations of the magnetic moment, which directly influences the amplitude of the signal generated by the surface ECP. Quantitative evaluations are provided for the eddy current distribution area produced by surface ECPs of eddy current flaw detectors, particularly those recommended for eddy current flaw detection of main gas pipelines. The study also identifies critical interprobe spacing parameters in multiprobe (matrix) ECP systems, including the maximum spacing that eliminates mutual interference and the minimum spacing that maximizes interactions between individual probes.