This is because angle beams can travel through a material by bouncing from surface to surface. Useful inspection information can be obtained at great distances from the search unit. When surface waves are used to inspect painted surfaces, you should exercise caution during set up and interpretation due to the possibility of surface reflection from scratches and breaks in the painted surface. On smooth surfaces, sound energy can travel long distances with little energy loss.
Surface waves travel around curved corners, and they reflect at sharp edges.
Eddy Current Inspection Eddy currents are electrical currents induced in a conductor of electricity by reaction with a magnetic field. The eddy currents are circular in nature, and their paths are oriented perpendicular to the direction of the applied magnetic field. Figure 15-16 shows eddy currents flowing in various configurations. Generation of the magnetic field results from an alternating current flowing through the coil. A fundamental consideration in selecting an eddy current probe or test coil is its intended use.