Great Lakes Testing, Inc.

Dye penetrant inspection (DP), also called liquid penetrate inspection (LPI) or penetrant testing (PT), is a widely applied and low-cost inspection method used to check surface-breaking defects in all non-porous materials (metals, plastics, or ceramics). The penetrant may be applied to all non-ferrous materials and ferrous materials, although for ferrous components magnetic-particle inspection is often used instead for its subsurface detection capability. LPI 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.

Strengths

Speed - Dye penetrant inspection is a relatively fast and cost effective inspection to quickly check the surface-breaking defects.

Area - It can be done effectively in tighter areas where space is limited.

Weaknesses

Surface Condition - The surface of the piece being inspected must be properly cleaned prior, and it cannot be a rough surface or you could get false indications.

Surface Indications Only - This method will not detect any subsurface indications, it must be open to the surface.