In eddy current testing, optimum sensitivity to a known defect on the surface of nonferrous tubing is obtained by:

In eddy current testing, achieving optimum sensitivity to detect surface defects in nonferrous tubing involves several critical factors, and all the aspects listed contribute to achieving this goal.

Firstly, the proper choice of frequency is crucial because the frequency of the eddy current can affect the depth of penetration and the skin effect, which is the phenomenon where the current density is highest near the surface of the conductor. Different defects may be best detected at specific frequencies, and selecting the right one ensures that the testing is sensitive to the particular characteristics of the material and the anomaly being investigated.

Secondly, centering the tubing in the coil is important for ensuring that the generated eddy currents are uniform across the surface of the tubing. Misalignment can lead to a decrease in sensitivity because it can create inconsistent current distribution, which may miss defects that are located just outside the areas being effectively tested.

Finally, proper adjustment of phase enhances the resolution of the eddy current measurement. The phase relationship between the excitation signal and the detected signal can indicate the presence of defects. Adjusting phase correctly allows for better differentiation between normal conditions and defective conditions, which plays a critical role in enhancing accuracy.

Combining these elements maximizes the overall effectiveness of the eddy current test, making it easier