Nondestructive testing (NDT) is a means of examining a material, product, or component (either internally or externally) without altering the item in any way that would impair its usefulness. Nondestructive testing can be used on raw materials, materials or components in process, or on a finished product. In addition, in-service NDT inspections may be conducted during the lifetime of the component. Originally used mainly for industrial products, NDT increased greatly with the advent ofWorld War II. The value ofNDT is seen in one's ability to test a product incurring no alteration whatsoever. Whereas other methods of detecting flaws may render a product unusable, the NDT process leaves the item in exactly the same condition after testing as it was prior to testing. The testing, nonetheless, is thorough and exacting, exposing any flaws or potential weaknesses that may present a dangerous situation in the future.