Wall Thickness - Ultrasonic thickness measurement (WT) is a method of performing non-destructive measurement of a thickness of a solid element (typically made of metal), based on the time taken by the ultrasound wave to return to the surface. This type of measurement is typically performed with an ultrasonic thickness gauge.
Ultrasonic waves have been perceived to travel through metals at a constant speed characteristic to a given alloy with minor variations due to other factors like temperature. Thus, given this information, called celerity, one can calculate the length of the path traversed by the wave using this simple formula:
Where : Lm = is the thickness of the sample
c= is the celerity or speed of sound in a given material
t= is the transverse or travelling time