Ultrasonic Flaw Detection is the non-destructive testing method that sends high frequency sound waves through the materials. If there is some blockage, some of the sound energy will reflect back which will indicate that there could be a defect. The signal will be shown on the instrument’s screen for further evaluation. Ultrasonic Testing method is useful for material inspection especially for flaw detection. This method can be used to detect both surface and subsurface discontinuities in almost all types of materials.
Ultrasonic Testing for Flaw Detection
Ultrasonic inspection is extremely useful and versatile method. It can be applied to use in many applications. This type of inspection can be ranging from the conventional to the advanced testing technique.
Conventional Ultrasonic Testing
Conventional Ultrasonic Testing use single piezoelectric crystal to create the high frequency sound wave. Conventional UT has been widely used to inspect flaws in many applications such as:
Weld inspection
Material inspection
Infrastructure
Petrochemical
Manufacturing
Aerospace
Automotive
Railways
Phased Array Ultrasonic Testing
Phased Array is the advanced system of the ultrasonic testing in which the physic remains the same as conventional UT. The main difference is that the piezo electric crystal is divided into multiple elements, and each crystal generates its own sound wave in highly controlled manner. With Phased Array system, we can have the sound wave in form of beam which can be controlled and steered according to the test requirement.
Phased Array Ultrasonic Testing has been developed to replace radiography testing (RT) and Conventional UT as this system can provide multiples advantages such as:
No safety concerned
Waveform recording
Automated reporting
Cover all angles from 35-70 degree
Can be integrated with other techniques
High probability of detection (POD)
Fast
This technique can be used in the applications similar to Conventional UT but in the faster manner.
Time of Flight Diffraction (TOFD)
TOFD is another technique of ultrasonic testing which has been recognized as the highly accurate sizing technique and highly repeatable. The combination of Phased Array and TOFD is becoming popular, effective, and efficient way of inspection. The advantages of TOFD technique are:
Covering a wide area
Fast encoding speed
Accurate sizing
Permanent data recording
Detect and sizing flaws in any orientations
High repeatability
Limitations of Ultrasonic Flaw Detection Method
Needs to be calibrated every time before use
Unable to inspect complex parts and rough surface
Operators need to be highly trained
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