PT or LPI is a widely applied non-destructive inspection method used to locate surface defects; such as cracks, laps and porosity in all non-porous materials by using capillary forces to make the discontinuities visible. LPI can also detect casting and forging defects, cracks and leaks in new products, as well as fatigue cracks on in-service components. By utilizing fluorescent dye surface flaws on nonporous materials will be revealed which might not otherwise be visible.

Welds are the most common item inspected, but plate, bars, pipes, castings, and forgings are also inspected using liquid penetrant examination.

Liquid penetrant testing, is a valuable inspection method for assessing new constructions, and in-service materials.

Liquid Penetrant Testing is highly sensitive to surface/sub-surface defects, it is very versatile as it can be used on a wide range of materials, with its cost effectiveness as equipment is simple and the testing process is straight forward, as well as the ease of use as it does not require highly specialized equipment.