DPI
Liquid penetrant testing is a non-destructive method used to detect surface breaking defects in any nonporous material. Liquid penetrant is applied to the surface and is drawn into defects by capillary action. Once a preset dwell time has passed, excess penetrant is removed and developer applied to draw out penetrant from defects. Visual inspection is then performed. Visible and Fluorescent Liquid Penetrant Examinations are Non-Destructive methods of revealing discontinuities that are open to the surfaces of solid and essentially non-porous materials, ferrous or non-ferrous.

• Strong dye sprayed onto surface drawn into cracks and pores by capillary action
• Surplus is wiped off
• Developer (e.g. chalk powder suspension) sprayed on to reveal defects
• Dye can be UV active so viewing under UV illumination reveals cracks

Applications:

• Grinding cracks
• Heat affect zone cracks
• Poor weld penetration
• Heat treatment cracks
• Fatigue cracks
• Hydrogen cracks
• Inclusions
• Laminations
• Micro shrinkage
• Gas porosity
• Hot tears
• Cold shuts
• Stress corrosion cracks
• Intergranular corrosion