Liquid Penetrant Inspection
Developer Properties and Control checks
Developer action
• Capillarity
Penetrant Inspection
• Penetrant drawn back out of the defect
by reverse capillary action
Developer action
• Capillarity
• Light scattering
Light Scattering
I0
If
If If
If
Light Scattering
If = I0 ( 1 - e-kcx )
If = Intensity of fluorescence
I0 = Intensity of UV light
k = Ability of penetrant to absorb UV light
c = Concentration of dye
x = Thickness of penetrant film
= Amount visible light dye will produce
Developer action
• Capillarity
• Light scattering
• Solvent action
Developer Properties
• Absorptive • Easily wetted
• Fine texture • Contrasting colour
• Able to mask out • Easily removed
background colour
• Non-toxic and
• Evenly and easily
Non-irritant
applicable
• Light and even coat
• Non-fluorescing
Control Checks
• Overall system performance
Overall System Performance
• Quench cracked aluminium alloy block
• Chromium plated cracked test panel
• Cracked test piece
Control Checks
• Overall system performance
• Water wash temperature and pressure
• Colour intensity
• Penetrant remover
• Developer
• UV lamp output
• UV monitor
• Water tolerance
Control Checks - Frequency
• Overall system performance
Daily
• Water wash temperature
Daily
and pressure
• Colour intensity
• Penetrant remover Weekly
• Developer Daily
Weekly
• UV lamp output
Monthly
• UV monitor
Annual
• Water tolerance
Weekly
Maintenance Checks
• Tank levels
• Equipment cleanliness
• Airline cleanliness
• Processing units
• UV lamp maintenance
• Clean tanks
