Electromagnetic ultrasonic combined flaw detection seamless pipe
Steel pipes and tubes are widely used in a variety of industries, including petroleum, automotive, chemical, and power generation. As a result of their frequent use, it has become increasingly important to ensure the quality of these materials. Nondestructive testing and inspection methods have gained increasing popularity for their ability to accurately and quickly detect flaws and imperfections within seamless steel tubes.
One of the most popular and cost-effective methods for NDT and NDI of seamless steel tubes is electromagnetic ultrasonic combined flaw detection (EUCD). EUCD is a hybrid technique that combines traditional electromagnetic acoustic transducer (EMAT) and phased array transducers to perform flaw detection. With its high sensitivity and signal-to-noise ratio, the combined approach provides a more comprehensive and accurate way of locating and evaluating the defects inside the tubes.
Working Principle of Electromagnetic Ultrasonic Combined Flaw Detection
EUCD is based on the principle of ultrasonic testing (UT). In UT, an ultrasonic signal is sent into the material and its reflection indicates the presence of flaws or imperfections in the material. In EUCD, both EMAT and phased array transducers are used to send out ultrasonic waves, detect the reflected signals and convert them into imaging signals.
EMAT can generate ultrasonic waves directly on the surface of the material, which makes it suitable for the detection of flaws on inner and outer surfaces of the seamless steel tube. The ultrasonic waves generated by the EMAT are in the form of compressional and shear waves that can penetrate the steel material. The reflected signals from the flaw can be detected and converted into imaging signals.
The phased array transducers are capable of generating ultrasonic waves from various angles, thereby increasing the sensitivity of the flaw detection. These transducers use linear and phased array scanning to inspect the steel tube for defects. The reflected signals from the flaws are also detected and converted into imaging signals.
Inspection Methodology
The EUCD technique involves inspection of the seamless steel tube with EMAT and phased array transducers. TheEMAT is first used to scan the outer surface of the tube and detect the weld seams. The ultrasonic waves generated by the EMAT will then be transmitted into the material and the reflected signals from the weld seams will be detected. The imaging signals obtained from the reflected signals will then be analyzed to determine the presence of any defects.
The phased array transducers are then used to scan the inner surface of the tube and detect any flaws or imperfections. The linear and phased array scanning technique used by the phased array transducers is able to detect a wide range of ultrasonic signals. These signals are then converted into imaging signals that are analyzed to detect the presence of any defects.
Signal Processing
The signal processing techniques used in EUCD are based on the principles of signal theory. The signal acquiring device used in EUCD is designed to capture the signals and convert them into digital signals. The acquired digital signals are then analyzed using digital signal processors to detect any flaws or irregularities that may be present in the seamless steel tube.
The signal analysis involves the use of coding and correlation techniques to detect any discrepancies in the ultrasonic signals received from the flaws. The coding techniques used include code alignment and phase discrimination techniques. The correlation techniques used include coherent and incoherent correlation techniques.
Results
EUCD has been found to be effective in detecting defects in seamless steel tubes. The technique has a high accuracy and sensitivity, which allows for the detection of small flaws and imperfections. The imaging signals obtained from EUCD are of high fidelity, providing a clear and concise picture of the flaws in the steel tube. The technique is also able to provide detailed information about the size and shape of the flaw, which can then be used for further analysis.
Application and Conclusion
EUCD is a cost-effective and versatile NDT and NDI technique that has been successfully applied to inspect seamless steel tubes. The technique has a high accuracy, sensitivity, and signal-to-noise ratio. The imaging signals obtained from the technique are of high quality, which allows for an accurate determination of the size and shape of the flaw. The technique is also able to provide a fast, reliable, and cost-effective way of ensuring the quality and safety of steel pipes and tubes.
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