What are the specified angles used in angle beam search units? (pitch and catch technique)

• A. 70°, 60° and 45°
• B. 60°, 45° and 30°
• C. 90°, 60° and 30°
• D. 50°, 40° and 30°

Answer: (A)

In angle-beam ultrasonic testing with pitch and catch, using multiple fixed beam angles lets you survey a defect from different directions, which increases the chances of detecting planar flaws that could be oriented in various ways inside a weld. The standard set of search angles used with common angle-beam wedges in welded steel is 70°, 60°, and 45°.

Why these angles matter: 70° is favored for probing near the weld root and centerline regions, where certain flaw orientations are common and strong reflections are produced by shear waves at that angle. 60° provides a middle path that Puts the wave at a different slant, improving sensitivity to flaws at intermediate orientations and depths. 45° offers a shallower, shallower-penetration path that highlights defects oriented differently or located nearer to the surface, such as those near the weld toe. Together, these three angles cover a broad range of possible flaw geometries in typical welds, making them the common choice for angle-beam search units using pitch and catch.

Other angle sets are not as commonly specified for standard weld inspection because they don’t provide the same broad coverage across defect orientations and depths with the usual wedges and steel properties.