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Eddy Current NDT Technology OverviewEddy Current NDT is a non-destructive testing method commonly used to detect surface and near-surface defects in conductive materials. Eddy current NDT can be used ...
In equipment corrosion detection, the detection technology is critical and directly affects the quality of the inspection. The use of pulsed eddy current testing is beneficial for improving the efficiency of equipment inspection. This article analyzes the application of pulsed eddy current testing technology in equipment corrosion inspection. It provides a detailed explanation of the new technology of pulsed eddy current testing and summarizes its application in equipment corrosion inspection.
Eddy current testing technology utilizes the principles of electromagnetic induction for detection. During the implementation process, the eddy current phenomenon, which occurs in electromagnetic induction, is used to analyze the magnetic field impedance within the equipment and understand its operational performance.
The application of eddy current testing technology in current equipment inspection is characterized by its speed, safety, and ease of use. It plays a crucial role in technical inspection applications. By combining pulsed eddy current with ultrasonic technology, a comprehensive scan of equipment and process pipelines is performed using specific sensors. This allows for the quick and accurate acquisition of wall thickness distribution, hazard locations, and severity in the tested area, providing data support for the maintenance and repair of equipment and process pipelines.
The sensor has a small diameter (generally less than 2 cm) to ensure detection accuracy. Typically, it cannot measure through insulation if the insulation layer is thicker than 4 cm. The scanning speed is relatively fast, allowing for continuous surface scanning. It often needs to be used in conjunction with ultrasonic technology.
The essence of precise scanning with pulsed eddy current is to increase the amount of detection data for the same pipe component by tens to hundreds of times, and this is achieved at a relatively low cost. In recent years, with increasing attention to safety issues in the social environment, petrochemical refineries have become more aware of safety in equipment operation management. Additionally, the government's related safety supervision departments have strengthened their oversight, leading to a growing demand in the petrochemical industry for more advanced non-destructive testing technologies.
Compared to traditional technologies such as ultrasonic and radiographic testing, which are widely used, pulsed eddy current scanning technology has several advantages:
Traditional ultrasonic testing is limited by the principle of ultrasonic conduction, requiring the pipe surface to be polished to a high degree of smoothness before testing, which demands a high level of surface flatness.
Pulsed eddy current technology, based on the principle of "electromagnetic induction," only induces responses in metallic conductors. Therefore, surface coatings, paint layers, rust layers, and non-metallic linings inside the pipe do not affect the testing process or results. Additionally, no coupling agents or other tools are needed, making it more convenient to use.
Ultrasonic testing is affected by "temperature drift" of sound speed and the melting and boiling points of coupling agents, making it significantly influenced by temperature.
Pulsed eddy current technology, based on the principle of "electromagnetic induction," is not affected by temperature. Successful applications have been documented in temperature ranges from -15°C to 500°C.
Compared to traditional ultrasonic "point detection," pulsed eddy current technology employs "surface scanning," which is more efficient. Because ultrasonic testing covers small surface areas, it is challenging to achieve comprehensive coverage, often leading to missed detections.
Pulsed eddy current technology scans surfaces. By dividing the pipe into several scanning surfaces according to its diameter and the probe size, full coverage and zero missed detections are achieved.
Traditional ultrasonic testing results are individual wall thickness values at various points, which are relatively isolated and less continuous. Pulsed eddy current technology uses real-time wall thickness imaging, showing the continuous variation trend of wall thickness distribution during scanning. This results in more continuous and intuitive detection outcomes.
Pulsed eddy current testing equipment uses an internal 12V lithium battery with low detection voltage. Based on the principle of "electromagnetic induction," it poses no harm to humans or the surrounding environment, making it safe for inspection personnel to use.
In conclusion, the development of pulsed eddy current testing technology greatly aids equipment corrosion detection. It has advantages such as high sensitivity, a wide detection range, and intuitive results. However, its operation requires consideration of the actual situation on site and the equipment, along with experienced inspection personnel, to ensure the accuracy of the results.
