Ultrasonic Flaw Detection is a volumetric NDT method. Typically used for finding lamination and testing full penetration welds. Ultrasonic Flaw Detection can accurately pinpoint the location and depth of defects so that they can interpreted to code acceptance or marked out for repair.
Ultrasonic thickness testing measures the material thickness by sending and receiving sound through the material. This form of thickness test is extremely useful in determining thickness when calipers or other measuring devices can not be applied to the edge of the material (eg: tanks, vessels or pipe). Typically used for assessing corrosion of steel or amounts of wear.