The science of sound is an ever-evolving and vast study. Sound waves, whether heard audibly or at such a high frequency that they cannot be heard by the human ear, have been constantly investigated over the years by scientists, engineers, doctors and individual entrepreneurs. Prior to World War II, sonar, the technique of sending sound waves through water and observing the returning echoes to characterize submerged objects and to find its distance from the sea level, inspired early ultrasound investigators to explore ways to apply the concept to medical diagnosis which was eventually applied to the industrial inspection of components. Initially, this technology was used to detect flaws in the metal hulls of Ships and Armor plates of battle tanks. It wasn’t long, though, before this practical application found its way into technology for radar and underwater navigation, as well as various other types of metal fabrication. Ultrasonic testing is a type of non-destructive testing using high frequency sound energy to find flaws in materials and to measure the thickness of objects. Many different industries benefit from the advancement of ultrasound technology. It can be used for flaw detection/evaluation, dimensional measurements, material characterization, segregation of coarse and fine grain materials and more. It is done in materials to determine the presence of defects by using high-frequency sound waves (typically 500kHz-20Mhz). In ultrasonic testing, an inspector will use a probe or some other kind of transducer to send sound waves through the material they want to test. If there are no defects in the material, the sound waves will pass through it, but if the sound waves hit a defect they will bounce off of it, indicating its presence which allows for accurate location on surface or subsurface discontinuities. Thus, course expands to basic theory of frequency, velocity, and wavelength as well as explains advanced theory, application, and variables such as beam profile, near and far zones, acoustic impedance, absorption, and sound characteristics. Other subjects pertaining to angle beam inspection include refraction, and mode conversion as well as calibration of equipment and characterization of flaws in accordance with appropriate acceptance standard integrated in the course curriculum to provide a detailed insights to the participant. Ultrasonic inspection has progressed from manual methods to computerized systems that automate much of the method.
There are following advanced techniques in the Ultrasonic Testing which can perform in lieu of Radiography Testing which can detect of surface , sub surface and internal discontinuities of volumetric and planner in nature. These techniques required conventional UT Level-II certification and experience as prerequisite.
• Time of Flight Diffraction (ToFD) Technique
• Phased Array Ultrasonic testing (PAUT) Technique
• Full Matrix Capture (FMC) Technique