DM5E Operating Manual ix
Preface
Testing Limitations
In ultrasonic testing, information is obtained only from within the limits of the sound beam. Operators must exercise great caution in making
inferences about the test material outside the limits of the sound beam. For example, when testing large materials it may be impossible or
impractical to inspect the entire test piece.
When a less-than-complete inspection is to be performed, the operator must be shown the specific areas to inspect. Inferences about the
condition of areas not inspected, based on data from the evaluated areas, should only be attempted by personnel fully trained in applicable
statistical and probability techniques. In particular, materials subject to erosion or corrosion, in which conditions can vary significantly in
any given area, should only be evaluated by fully trained and experienced operators.
Sound beams reflect from the first interior surface encountered. Because of part geometry and overlapped flaws or overlapped surfaces,
thickness gauges may measure the distance to an internal flaw rather than to the back wall of the material. Operators must take steps to
ensure that the entire thickness of the test material is being examined.
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