How is liquid penetrant inspection performed?

In liquid penetrant inspection, a liquid penetrant is applied to the surface of a material to detect defects such as cracks, voids, or other discontinuities. The process begins with the application of the penetrant, which is spread over the surface and allowed to soak for a specific period. This soaking time is crucial as it allows the penetrant to seep into any surface-breaking flaws. After the soaking time, the penetrant is then removed, typically by using a cleaner that will not disrupt the penetrant that has entered the flaws.

This method is effective for non-porous materials and relies on the principle of capillary action, where the liquid fills defects that may be too small to be seen with the naked eye. After the cleaning process, a developer may be applied, which draws the penetrant out of the defects and reveals them visually. The effectiveness of this method relies on the appropriate choice of penetrant and the conditions under which the inspection is carried out.

While the other options mention aspects related to inspection methods, they do not accurately describe the standard liquid penetrant inspection process. For instance, using a liquid with high surface tension, applying a powder, or injecting liquid into welds does not reflect the commonly accepted methodology for performing liquid