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

What can liquid penetrant testing be used to locate?

1. Discontinuities open to the surface

2. Hidden internal flaws

3. Surface color variations

4. Surface scratches only

The correct answer is: Discontinuities open to the surface

Liquid penetrant testing is primarily used to locate discontinuities that are open to the surface of a material. This method involves applying a penetrant to the surface, allowing it to seep into any surface-breaking flaws, such as cracks, porosity, and laps. After a certain dwell time, the excess penetrant is removed, and a developer is applied to draw the penetrant out of the flaws, making them visible for inspection. This technique is specifically designed to identify defects that are accessible from the surface, as the penetrant requires an uninterrupted path to enter the discontinuity. Other issues like hidden internal flaws are better suited for different testing methods like ultrasonic or radiographic testing. Similarly, while surface color variations may be visually noted, they do not correlate with manufacturing defects and aren't identified as flaws by liquid penetrant methods. Surface scratches may be detected, but they are only a subset of the types of discontinuities that liquid penetrant testing can find, making the identification of broader surface defects more significant for the method's purpose.