ASNT

discontinuities, with the result of possible part failure in service. A cautious inspector may reject parts that contain discontinuities but also may reject parts that do not contain discontinuities, with the result of unnecessary scrap and repair. Neither inspector is doing a good job. SUMMARY As noted in this discussion, many factors must be considered before a program of nondestructive testing can begin. To manage a nondestructive testing program, many options must be considered. The final decision for a path forward must be based on requirements (codes, standards, and specifica- tions) and what is best for the project. If a company lacks the expertise for these critical decisions, it can hire an expert, such as a contractor who holds a Level III certificate in radiographic testing.

ENSURING RELIABILITY OF TEST RESULTS When a test is performed, there are four possible outcomes: (1) a discontinuity can be found when a discontinuity is present; (2) a discontinuity can be missed even when a discontinuity is present; (3) a discontinuity-type indication can be observed when no discontinuity is present; and (4) no discontinuity is found when none is present. A reliable testing process and a reliable inspector should find all discontinuities of concern with no discontinuities missed (no errors as in case 2, above) and no false calls (case 3, above). To achieve this goal, the probability of finding a discontinuity must be high and the inspector must be both proficient in the testing process and motivated to perform at maximum efficiency. A reckless inspector may accept parts that contain

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Part 3