Tag Archives for Ultrasonic
Ultrasonic Examination – Hydrogen Blisters
The use of longitudinal wave UT for detecting, locating, and determining the size of hydrogen blisters is illustrated in Figure 700-17. The blisters are internal flaws that have a reflecting surface at a depth from the front surface that is … Continue reading
Ultrasonic Examination – Remaining Thickness
Figure 700-16 illustrates the use of longitudinal UT for determining the remaining thickness of a corroded shell. If the transducer is placed on a location of the shell component that is not corroded, as depicted by the position of Transducer … Continue reading
Ultrasonic Examination – Calibration
Calibration of longitudinal wave UT consists of developing a “distance amplitude curve (DAC)” for the instrument and transducer, using test blocks manufactured from a material similar to the workpiece (i.e., with the same velocity of sound). Calibration for determining the … Continue reading
Ultrasonic Examination – Longitudinal Wave UT
Longitudinal wave UT is used primarily to determine the remaining thickness of corroded shell components, including the depth of pits. It can also be used to detect internal flaws that have developed during service and that have a reflecting surface … Continue reading
Ultrasonic Examination – Couplants
Attenuation of ultrasonic waves propagating through air is very high, and normal surface roughness (especially of the workpiece) will always create an air gap between an ultrasonic transducer and the workpiece. It is not practical to improve the surface of … Continue reading
Ultrasonic Examination – Ultrasonic Transducers
Ultrasonic waves for UT are created in a metal workpiece with a piezoelectric transducer that is coupled to the workpiece. The piezoelectric transducer converts high frequency electrical impulses into correspondingly high frequency mechanical vibrations that induce ultrasonic waves in the … Continue reading
Ultrasonic Examination Instruments
Most UT systems used for the in-service inspection of a pressure vessel employ a “pulse-echo” method of operation, in which the same transducer (described below) that creates the ultrasonic wave (pulse) is also used to detect any ultrasonic waves (echos) … Continue reading