Detection of Defects in the Tubes of Refrigerators of Locomotive Diesel Engines by the Eddy Current Method

Abstract

We describe a dynamic eddy current flaw detector for the testing of thin-walled brass tubes with rotation of the eddy current transducer around them. We show that the eddy current method makes it possible to detect the greatest number of defective tubes as compared with the visual and hydraulic-test methods. The productivity of the eddy current method is 8 – 10 times as high as that of other methods. It enables one to evaluate the depths of defects and, correspondingly, the degree of their danger by the signal amplitude of the eddy current flaw detector. We show the possibility to set an optimal reject criterion and the corresponding level of operation of the threshold device of the flaw detector. The rejection of tubes with defects deeper than the assigned value makes it possible to decrease the number of wrongly rejected tubes. The LEOTEST VD-5D dynamic eddy current flaw detector was introduced in the technological process of full-scale locomotive production.