How can a technician identify a discontinuity in a component during Liquid Penetrant Testing?

When employing Liquid Penetrant Testing (PT), the primary method for identifying a discontinuity in a component involves observing indications or markings that develop after the penetrant application. After the penetrant is applied and allowed to penetrate any surface-breaking defects, a developer is introduced. This developer acts to draw the penetrant out of the discontinuities and onto the surface, where it becomes visible. These indications typically appear as distinct features, such as colored lines or spots, which signal the location and sometimes the severity of the discontinuity.

This process relies heavily on the interaction between the penetrant and the surface features of the material. It is not solely based on visual inspection alone; the development process is crucial in making the defects apparent. The technique emphasizes the importance of viewing the component after applying the developer, as this is when the technician sees evidence of any cracks, voids, or other defects that may not have been noticeable beforehand.

Identifying discontinuities requires proper technique and practice, ensuring that the penetrant is adequately absorbed and brought to the surface by the developer, which in turn enhances the technician's ability to identify issues within the material effectively.