Liquid Penetrant Inspection (PT), PT is used to detect casting, forging and welding surface defects such as hairline cracks, surface porosity, cold lap, and fatigue cracks on in-service components.
The method has high sensitivity to small surface discontinuities. The method has few material limitations, i.e. metallic and nonmetallic, magnetic and nonmagnetic, and conductive and nonconductive materials may be inspected. Large areas and large volumes of parts/materials can be inspected rapidly and at low cost. Parts with complex geometric shapes are routinely inspected. Indications are produced directly on the surface of the part and constitute a visual representation of the flaw. Aerosol spray cans make penetrant materials very portable. Penetrant materials and associated equipment are relatively inexpensive.