Liquid Penetrant Testing Level 1 (PT-1) Practice Exam

Which of the following discontinuities can be found by the penetrant test method?

1. A surface crack

2. An internal cavity

3. A deep void

4. A subsurface flaw

The correct answer is: A surface crack

The penetrant test method is specifically designed to detect surface discontinuities in non-porous materials. A surface crack is a perfect example of what this testing method can identify. When the penetrant is applied to a part, it seeps into any surface-breaking discontinuities, such as cracks or laps. After the excess penetrant is removed and a developer is applied, it draws the penetrant out of the defect, making it visible under ultraviolet or white light. This allows the inspector to identify the presence, location, and extent of surface cracks, making the penetrant test method particularly effective for assessing surface integrity. In contrast, the other options describe types of discontinuities that are not detectable using the penetrant testing method. Internal cavities, deep voids, and subsurface flaws do not break the surface and therefore are not accessible to penetrants. As a result, these types of discontinuities require other non-destructive testing methods, such as ultrasonic testing or radiographic testing, to be effectively evaluated.