What is a common disadvantage of using ultrasonic testing?

Ultrasonic testing (UT) is widely used for its effectiveness in detecting internal flaws and measuring material thickness, but it does have its challenges. When it comes to thick materials or complex geometries, UT can face difficulties because the sound waves must travel through the material and can be reflected or refracted in unpredictable ways. This can result in decreased sensitivity or accuracy in identifying flaws, particularly in areas with complex shapes or significant thickness, where the sound may not be able to penetrate adequately to provide reliable results.

The other factors mentioned, such as cost, surface flaw detection limitations, and setup time, are relevant considerations but are not as significant or intrinsic to the methodology of ultrasonic testing as the challenges posed by thick materials or complex geometries. Hence, the challenge with thick and complex geometries stands out as a primary disadvantage of ultrasonic testing.