Eddy Current Technique (ECT)
ECT was developed to test non-ferrous metals. TesTex expanded upon this technique with the help of automated software and high speed probe driving and pulling mechanisms. This method is effective in detecting a variety of internal and external defects such as general corrosion, erosion, pittings etc.
Brief about Technique:
Any eddy current is defined as a circulating electrical current induced in a conducting tube by an alternating magnetic field. As the magnetic field alternates, so does the eddy current (reverses). This eddy current flow is limited to the area of the inducing magnetic field. Figure # 1 illustrates a typical eddy current induced in an tube by the probe. Note that eddy current travel parellel to the tube.
Artificial Flaws are prepared for calibration. As the probe moves through the flaws shown in figure # 1, the lissajous signal is generated. For details please refer figure # 2, thus the flaw is quantified. Ensure that the lissajous signal moves from down and to the right, it should follow that the OD Signal is centralised on the vertical axis and ID Signal is centralised on the horizontal axis, whereas Hole signal comes around 30 degree. The seperation between ID Signal and OD Signal are at 90 Degree.
