Liquid Penetrant Testing (PT)

Liquid penetrant testing, also called dye penetrant inspection (DPI) or penetrant testing (PT), is a widely applied and low-cost inspection method used to locate surface-breaking defects in all non-porous materials (metals, plastics, or ceramics). The penetrant may be applied to all materials, although for ferrous components magnetic-particle inspection is often used instead for its subsurface detection capability. PT is used to detect surface defects in castings, forgings and welds such as hairline cracks, surface porosity, leaks in new products, and fatigue cracks on in-service components. PT is based upon capillary action, where low surface tension fluid penetrates into clean and dry surface-breaking discontinuities. Penetrant may be 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 that an invisible indication becomes visible to the inspector. Inspection is performed under ultraviolet or white light, depending on the type of dye used - fluorescent or nonfluorescent (visible).

  • LP01
  • LP02
  • LP03
  • LP04
  • LP05