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Liquid Penetration Tests on Metals (NDT) AND ITS PROCESS

 These tests reveal discontinuities that are open to the surface and may use dyes or fluorescent materials. They are specially useful for non ferrous metals and non - metallic substances. The simple test involves dipping the component into kerosene, wiping it dry, and then coating it thinly with whiting. cracks will be revealed by a discolored 'line" appearing in the "whiting", this being produced when kerosene trapped in the cracks seeps out slowly. Dyes may be used instead of kerosene , but fluorescent materials are probably the most widely used. 




In the fluorescent test, the sample is immersed for sometime in a hot bath of a strongly fluorescent compound such as anthracene, used as a penetrating agent. The solution enters the cracks, if any, and remains there. The metal is then dried and examined under a quartz tube mercury vapor lamp. Any penetrated solution will be detected by the fluorescence caused by the ultraviolet radiation of the light. 

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