Wall Thickness Gauges
With ultra-sound measuring techniques wall thicknesses can be non-destructively determined. Before testing, a coupling gel will be applied to the surface of the workpiece. The ultrasonic pulses emitted by the probe hit the material to be tested, penetrate the material and are reflected from it. The material thickness can be exactly determined by means of the time during which the ultrasonic waves propagate through the object.
Table of sound velocity in various materials (m/s):