What does liquid penetrant testing primarily detect?

Liquid penetrant testing is a non-destructive testing method primarily used to identify surface-breaking defects in non-porous materials. This technique involves applying a liquid to the surface of the material, which penetrates into any cracks or voids. After a certain dwell time, the excess liquid is removed, and a developer is applied, which draws the penetrant out of the defects and makes them visible under ultraviolet or white light.

The method is particularly effective for detecting surface discontinuities such as cracks, laps, seams, and porosity. These types of defects are crucial to identify as they can significantly affect the integrity and strength of the component. Because this testing requires the discontinuities to be open to the surface, it is not effective for finding defects that are buried or located within the material where the penetrant cannot access them.

In contrast, the other options refer to scenarios that are either unrelated to the surface-level testing that liquid penetrant testing provides or describe conditions that are not within the capability of this specific testing method.