Ultrasonic testing is used under which condition?

Ultrasonic testing is a non-destructive testing method widely utilized in pipeline welding inspections to detect internal defects and measure wall thickness. The method is particularly valuable in applications where visual inspection is insufficient or where welds are in hard-to-reach areas.

The correct choice emphasizes that ultrasonic testing is employed when contractors can demonstrate acceptable testing procedures. This requirement is crucial since the reliability of ultrasonic testing heavily depends on the technician's skill and the established procedures for conducting the tests. It ensures that the testing is performed correctly and that the results are valid and usable for quality assurance in welded joints.

In contrast, while options referring to specific limitations or scopes may imply constraints on ultrasonic testing, they do not address the need for a contractor to establish competence and adequate procedures essential for ensuring effective testing results. This highlights the importance of solid procedural frameworks and training in the accurate application of ultrasonic testing techniques in pipeline welding contexts.