Phased Array Technology Plays Major Role in The NDE Inspection Field
Benefits Include Multiple Applications and Quick, Efficient Production
Written by Mike Forbes, National Sales Manager, TUV Rheinland Industrial Solutions
Since its emergence in the 1940s, the use of high frequency sound waves (Ultrasonics) have been utilized to propagate through a solid material that detects hidden indications. Ultrasonics have been proven to be a safe and non-destructive means of inspection in numerous industries, especially applications involving welds and structural metals.
The latest advances in ultrasonic instruments have been based on the digital signal processing techniques, coupled with the newer inexpensive microprocessors that have become available. These instruments are much smaller and more accurate in determining the size and location of defects.
Through these continuous improvements in technology (the ability to detect smaller flaws), combined with a better understanding of fracture mechanics, companies are now able to predict the remaining life of a component or structure. Components that have known defects can be monitored, and the schedule of repairs or replacements can then be determined depending on the size and propagation rate of the indication. In addition, these advances in technology have allowed equipment to perform multiple scans at different angles, allowing for better detection and mapping of discontinuities. This method is called Phased Array Ultrasonics.
Phased array ultrasonic inspection can be employed in almost any test where regular, conventional ultrasonic inspection is utilized. Weld inspection and crack detection are the most common applications, and they are performed across a wide array of industries, including: aerospace; petrochemical; power generation; and, general manufacturing. Phased arrays can also be effectively utilized to profile remaining wall thickness for corrosion survey applications.
Composite structures, especially in aircraft manufacturing, are growing dramatically. Currently, one of the best inspection methods utilizes ultrasonic technology, specifically phased array. Phased array methods are a very effective means to inspect composite structures integrity by checking for delaminated or disbonded materials.
The direct benefits of phased array technology, over other methods, are dependent on which method or which application is applied. For instance, the benefits of phased array over conventional ultrasonic methods include the ability to use multiple elements to steer, focus and scan beams with a single transducer. Through beam steering, the operator is able to map components with complex geometry. The smaller footprint of the transducer with the ability to sweep the beam, without moving, adds to the capabilities of scanning smaller complex pieces. The ability to sweep welds with multiple angles increases the probability of detecting flaws, and the ability to focus at multiple depths improves the ability to size critical defects for volumetric inspections. Utilizing multiple channels and electronic scanning capabilities allows for accurate three dimensional mapping capabilities.
When comparing the benefits of phased array technology against radiography (RT), phased array stands out since it can provide you compatible accuracy and mapping capability (a similar profile of indications as film), however, you are not limited in the thickness of steel like radiography. The area of operation is never shut down due to radiation barriers and the phased array ultrasonic inspection can be operated at the same time as the welding operation - leading to quicker repairs and better production.
Currently, the potential disadvantages of phased array technology can be seen in a much higher cost of equipment and the requirement of in depth operator training. However, these expenses can be easily offset by the numerous advantages including reduction of inspection time.
Looking forward, phased array technology has numerous applications (as well as benefits) and it will play a major role in the NDE inspection field. With more changes in technology and more technicians being trained in the application of phased array ultrasonic inspection, the method will expand and provide new levels of flaw detection in the industry.
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For more information, please call toll-free at 1-TUV-RHEINLAND (1-888-743-4652) or visit www.us.tuv.com.