Three-Dimensional FEM Analysis of Electromagnetic Inspection of Outer Side Defects on Steel Tube Using Inner Coil

Steel tubes are used in the heat exchanger in the petrochemical plant. Since these steel tubes in the heat exchanger are stored as a bundle, it is necessary to inspect the defects of these tubes from the inside of tube. In this paper, problems in applying the alternating flux leakage testing method for the inspection of the outer side defect on steel tube are examined using 3-D finite element method. The features of detecting property of outer side defect using an inner coil at low-frequency are investigated by analyzing the flux and current distribution. It is shown that the inspection of the outer side defect on a steel tube with cooling aluminum fin is possible using the proposed method