Dye Penetrant Inspection (PT)

Dye penetrant inspection (DPI) or penetrant testing (PT) is a widely applied inspection method used to locate surface-breaking defects in all non-porous materials (metals, plastics, or ceramics). DPI is used to detect casting, forging and welding surface defects such as hairline cracks, surface porosity, leaks in new products, and fatigue cracks on in-service components.

DPI is based upon capillary action, where low surface tension fluid penetrates into clean and dry surface-breaking discontinuities. Penetrant is applied to the test component by dipping, spraying, or brushing. After adequate penetration time has been allowed, the excess penetrant is removed and a developer is applied. The developer helps to draw penetrant out of the flaw so the indication becomes visible to the qualified ASNT TC-1A inspector. Inspection is performed under ultraviolet or white light, depending on the type of dye used -fluorescent or nonfluorescent (visible).

  • Dye Penetrant Inpsection 1
  • Dye Penetrant Inpsection 2
  • Dye Penetrant Inpsection 3
  • Dye Penetrant Inpsection 4


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  • Highly portable
  • Non destructive technique
  • Fast inspection process
  • Can be used on welds and base materials
  • Detects casting, forging, and welding surface defects
  • Non hazardous to operations instrumentation or personnel
  • AWS D1.1
  • ASTM E1417
  • Ferromagnetic and non-ferromagnetic materials up to 20 feet or greater
  • Non-porous materials