An ultrasonic thickness gauge measures material thickness using high-frequency sound waves, usually with access from one side. It supports non-destructive inspection of pipes, tanks, pressure vessels and other components where wall thinning caused by corrosion or erosion needs to be monitored.

These instruments are used for maintenance inspections, fabrication checks and condition monitoring. Reliable measurements depend on the material, surface condition, probe selection and correct calibration. Measurement through coatings requires a suitable gauge, probe and measurement mode.