2
• Effects of the sound velocity of the test material
• Behavior of the sound wave where two different materials are in contact
• Areas covered by the sound beam
More specific information about operator training, qualification, certification and test specifications is available from
various technical societies, industry groups, and government agencies.
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 maybe 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 subjects to corrosion or erosion, in which
conditions can vary significantly in any given area, should be evaluated only by fully trained and experience operators.
Sound beams reflect from the first interior surface encountered. Because of part geometry and overlapped flaws or
overlapped surface, 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.
UltrasonicThickness Measurement Critical Operating Procedure
The following operating procedures must be observed by all users of ultrasonic thickness gauges in order to minimize
errors in test results.
To Next Page
Loading...
