Liquid Penetrant Testing

This Non-Destructive Testing Method involves applying a liquid to the surface of a material and leaving it to rest for a pre-determined period of time. The liquid can be either a colour that is easily visible under normal lighting conditions or a yellow/green fluorescent colour that requires special lighting conditions to be effective.

During the Liquid Penetrant Testing the liquid dye enters into discontinuities that are open to the surface of the material through a phenomenon known as "capillary action". This capillary action takes place through the resting time and the discontinuity retains this dye when the excess is cleaned from the surface. A certain type of developer is then applied to the surface of the material and the dye that is trapped inside the surface discontinuities is blotted back out on to the surface and forms an indication. This indication is then interpreted by a qualified interpreter.

The Liquid Penetrant Testing method, also know as Dye Penetrant Examination is suitable on most non-absorbent materials.

SGS provides not only Non-Destructive Testing and Services for this method but also offers Liquid Penetrant Testing Courses.