In this topic, you will learn about Dye/Liquid Penetrant testing and their advantages and disadvantages.
This method is used to detect flaws that are open to surface such as cracks, porosity and shuts.
Dye penetrant test can be effectively used in inspection of ferrous and especially non-ferrous metals such as plastic, glass and ceramics. This is also used to test the weld works.
The Specimen which is to be inspected is chemically cleaned first to remove the dirt and other foreign particles.
Next, the penetrant which is a very fine thin oil usually dyed bright red or ultraviolet fluorescent is applied and allowed to remain contact with the the surface for 10 minutes.
During this period, capillary action draws the penetrate into the crack.
The surplus penetrant on the surface is removed completely and thin coating of powder chalk is applied.
After certain minutes the chalk draws the dye out of the crack to form visible indication of flaws commonly known as bleed out.
Inspector, carries out his inspection after 3 to 5 minutes of development time using ultraviolet radiation.
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