What is the main limitation of ultrasonic testing?

The main limitation of ultrasonic testing lies in its requirement for a good acoustic coupling between the transducer and the test material. This is crucial because ultrasonic waves need a medium to travel efficiently, and poor coupling can lead to inaccurate readings or even missed defects. Proper coupling ensures that the sound waves penetrate the material effectively, allowing for an accurate assessment of internal structures or flaws.

While other aspects of ultrasonic testing can also present challenges—such as surface flaw detection, training requirements, and record-keeping—these do not represent the fundamental limitation that affects the efficacy of the test itself as directly as the need for effective acoustic coupling. Without good coupling, the entire testing process can be compromised, making this aspect a primary concern in the operation of ultrasonic testing.