Non-Destructive Testing
Meaning ~ Inspection techniques that evaluate the internal structure of manufactured materials without causing damage represent a formal verification category.
Ultrasonic Thickness Testing
Meaning
Ultrasonic gauging methods calculate the distance between a probe and a back wall to determine material thickness. The process of ultrasonic thickness testing sends a high-frequency sound wave through the material and measures the time it takes to return. This technique is used to monitor corrosion in pipes and storage tanks from the outside.
It provides a precise digital reading without the need for cutting or disassembly.
Acoustic Measurement
Velocity of the sound wave depends on the type of material being measured. In ultrasonic thickness testing the gauge must be calibrated to the specific speed of sound for the steel or plastic. Using a couplant liquid is necessary to bridge the air gap between the probe and the surface.
Without this fluid the sound wave would reflect off the air and never enter the part.
Wall Depletion
Periodic inspections of high-pressure lines help predict the remaining service life of the equipment. Data from ultrasonic thickness testing allows engineers to identify areas of thinning before a leak occurs. Mapping the wall loss over time provides a clear picture of the wear patterns inside a refinery or chemical plant.
Measurement Range
Capabilities of the equipment vary based on the frequency of the transducer. Very thin materials require a high-frequency probe while thick or grainy materials need a lower frequency. In ultrasonic thickness testing a common error is the doubling of the reading when the part is extremely thin.
Coatings on the surface can also lead to false readings unless the gauge has an echo-to-echo feature.