AWS Certified Welding Inspector — FundamentalsNondestructive Examination (NDE)Medium
A CWI is reviewing an Ultrasonic Testing (UT) procedure for inspecting a thick-walled pressure vessel. The procedure specifies the use of a normal beam transducer. What type of discontinuity is this transducer primarily designed to detect?
- ALaminations or inclusions parallel to the surface
- BLack of sidewall fusion in fillet welds
- CRoot penetration issues in butt welds
- DSurface-breaking cracks
Show answer & explanationAnswer & explanation
Correct answer: A. Laminations or inclusions parallel to the surface
Normal beam (straight beam) transducers introduce sound waves perpendicularly into the test material. This orientation is most effective for detecting discontinuities that are parallel or nearly parallel to the scanning surface, such as laminations, inclusions, or hydrogen flakes. Discontinuities like surface cracks, lack of sidewall fusion, and root penetration issues are better detected with angle beam transducers.
Why the other options are wrong
- B. Lack of sidewall fusion in fillet welds requires an angle beam transducer to direct sound into the fusion zone.
- C. Root penetration issues in butt welds are best detected by angle beam UT, as the sound needs to travel to the root area.
- D. Surface-breaking cracks are typically better detected by angle beam UT or surface NDE methods like PT/MT.
Normal Beam UT Transducer
An ultrasonic transducer that introduces sound waves into the material perpendicular (at a 0-degree angle) to the test surface.
- Used for detecting discontinuities parallel to the surface.
- Commonly used for thickness measurement and detection of laminations.
- Produces longitudinal waves.
Memory trick: Normal is straight, angle is bent, surface is a special friend.