Dye Penetrant Inspection (DPI) also called as Liquid Penetrant Inspection (LPI) or Penetrant Test ( PT) is fast, economical and widely used non destructive test method to detect surface-breaking discontinuities in all non-porous materials (metals, plastics, or ceramics).
Penetrant based upon the principles of capillary action where liquid penetrates into a cavity.
Penetrant test is performed by cleaning the test surface thoroughly, applying coloured or fluorescent penetrant, allowing dwell time, removal of excess penetrant followed by application of developer ( dry or liquid form).
The developer draws penetrant out from the surface discontinuities.
After developer dwelling surface is examined for bleed out under natural light or black (UV) light (depending on the type of penetrant).
