NCCER Millwright Practice Exam

What can be determined from liquid penetrant testing?

1. Internal structure integrity

2. Surface flaws

3. Thermal properties

4. Chemical composition

The correct answer is: Surface flaws

Liquid penetrant testing is a non-destructive testing method used primarily to identify surface flaws in materials. This technique relies on the ability of a liquid penetrant to seep into surface-breaking defects, such as cracks or voids, which are typically not visible to the naked eye. After applying the penetrant, excess material is removed, and a developer is applied, drawing the penetrant out of the flaws and making them visible under UV light or normal light conditions. This is crucial in many industries, particularly in metal fabrication, where the strength and integrity of a surface can significantly impact the overall performance of a component. Other choices relate to aspects that cannot be accurately assessed through liquid penetrant testing. For instance, internal structure integrity is evaluated using methods like ultrasonic or radiographic testing, which can penetrate material to assess subsurface conditions. Thermal properties involve understanding how materials respond to temperature changes, which requires different testing techniques. Chemical composition can be determined using methods like spectroscopy or chemical analysis, rather than through surface assessment methods like liquid penetrant testing. Therefore, recognizing that liquid penetrant testing is explicitly designed to detect surface flaws is crucial for understanding its application in various fields.