Dye Penetrant Inspection (DPI)

Dye Penetrant Testing involves applying a liquid penetrant to the surface of a material. The penetrant seeps into surface-breaking defects, and after excess penetrant is removed, a developer is applied to make the defects visible. LPT is particularly effective for detecting small cracks, porosity, and other surface discontinuities.


• Portable (on-site and in-house).
• Relatively simple method.
• Sensitive.

What defects/indications can it detect?

• Surface breaking defects.
• Toe cracks.
• Surface porosity.
• Crater cracks.


• Uses a flammable liquid.
• Power may be needed.
• Temperature dependent.
• A clean surface is required before inspection.

Alternative inspection methods

• Magnetic Particle Inspection (MPI) Note: Only on ferromagnetic materials.
• Eddy Current Inspection (EC).