Liquid penetrant inspection (LPI) is used to detect surface-breaking defects in varied materials. It can be used on a variety of materials, including both metallic and non-metallic surfaces, conductive and non-conductive objects, and magnetic and non-magnetic surfaces. LPI is versatile across geometric shapes and can detect extremely small defects and impurities.
The inspection relies on the dye’s penetration capability, where it is applied to the surface and absorbed by any discontinuities or defects. After removing the penetrant, a developer is applied to visually inspect for irregularities and assess material durability.
Liquid Penetrant Inspection offers several advantages over other non-destructive testing (NDT) methods.
1. High Sensitivity to Surface Defects
LPI excels at detecting small, surface-breaking flaws such as cracks, porosity, laps, seams, and other discontinuities that may not be visible to the naked eye. It can even reveal cracks as narrow as 150 nanometres. This sensitivity is crucial for ensuring the integrity and safety of components across various industries including aerospace, the military and oil & gas.
2. Versatility Across Materials
Unlike some other testing methods like Magnetic Particle Inspection (MPI), which is limited to ferromagnetic materials, LPI can be applied to a wide range of non-porous materials. This includes both metallic (ferrous and non-ferrous) and non-metallic materials like plastics, ceramics, and composites. This versatility makes LPI a valuable tool in diverse manufacturing and maintenance applications.
3. Efficiency
Compared to more complex NDT methods like radiography or ultrasonic testing, LPI can be considered fairly efficient, with the ability to test large areas or a high volume of parts simultaneously. Liquid penetrant inspection can be carried out on-site as the materials and equipment needed are portable, or in a controlled lab environment.
To discuss Liquid Penetrant Inspection, contact the ATH NDT team.