Ultrasonic Thickness Measurement (UTM)
UTM is a method of performing non-destructive measurement (gauging) of the local thickness of a solid element (typically made of metal, if using ultrasound testing for industrial purposes) basing 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.
Does not require access to both sides of the sample
Can be engineered to cope with coatings, linings, etc.
Good accuracy (0.1 mm and less) can be achieved using standard timing techniques
Can be easily deployed, does not require laboratory conditions
Relatively cheap equipment
No need to remove the coating of the metal