Principles
DPI is based upon capillary action, where low surface tension fluid penetrates into clean and dry surface-breaking discontinuities. Penetrant may be applied to the test component by dipping, spraying, or brushing. After adequate penetration time has been allowed, the excess penetrant is removed, a developer is applied. The developer helps to draw penetrant out of the flaw where an invisible indication becomes visible to the inspector. Inspection is performed under ultraviolet or white light, depending upon the type of dye used - fluorescent or nonfluorescent (visible).
Read more about this topic: Dye Penetrant Inspection
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“...at this stage in the advancement of women the best policy for them is not to talk much about the abstract principles of women’s rights but to do good work in any job they get, better work if possible than their male colleagues.”
—Virginia Crocheron Gildersleeve (1877–1965)
“The scope of modern government in what it can and ought to accomplish for its people has been widened far beyond the principles laid down by the old “laissez faire” school of political rights, and the widening has met popular approval.”
—William Howard Taft (1857–1930)
“Our national determination to keep free of foreign wars and foreign entanglements cannot prevent us from feeling deep concern when ideals and principles that we have cherished are challenged.”
—Franklin D. Roosevelt (1882–1945)