High temperature performance of ultrasonic guided wave system for structural health monitoring of pipeline
High temperature performance of ultrasonic guided wave system for structural health monitoring of pipeline
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发表时间：
2019
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通讯作者：
A. Dhutti;T. Gan;W. Balachandran;J. Kanfoud
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作者：
A. Dhutti;T. Gan;W. Balachandran;J. Kanfoud
发电厂营运商致力提高营运效率及减少排放。这是通过提高关键部件（如管道）的工作温度来实现的。这些高温（HT）管道长时间暴露在极端操作条件下，并且由于热疲劳而遭受强度降低。它们会出现裂缝；如果不被发现，可能会导致灾难性的失败。研究了超声导波技术在高温管道在役结构健康监测中的应用。UGW使用放置在管道周围的压电换能器阵列，当被激发时产生沿管道边界定义的路径传播（数十米）的应力波。由于截面的变化，通过反射超声来检测缺陷。该技术被广泛用于离线检测，以监测腐蚀型缺陷，因为它限制在环境温度下运行。为了实现高温管道的SHM，开发了一种使用高温换能器和固定接箍的高温- ugw系统。高温传感器的超声响应对温度变化和时间变化高度敏感，这可能导致误报警。最初，进行了长期的实验室实验，以评估温度对系统及其监测能力的影响。该系统表现出稳定的热响应，在高温下可以检测到2%的截面变化。然后将该系统安装在高达200°C的管道上运行了1年多，并分析了运行中的UGW （4060kHz范围内的T（0,1）波模式）数据，以研究温度负载和温度随时间对系统性能的影响。这项工作的发现增加了人们对UGW技术用于HT-SHM的信心，并将有助于在不同温度范围内改进缺陷检测的增强温度补偿的发展。
Power plant operators strive to maximise their operating efficiency and reduce plant emissions. This is achieved by increasing operating temperature of critical components such as pipework. These high temperature (HT) pipework are exposed to extreme operating conditions for prolonged periods and are known to suffer strength reduction due to thermal fatigue. They can develop cracks; which if undetected, can lead to catastrophic failures. This study investigates application of Ultrasonic Guided Wave (UGW) technique for in-service structural health monitoring of HT pipework. UGW uses arrays of piezoelectric transducers placed around the pipe and when excited produce a stress wave which propagates (tens of meters) along the path defined by the boundaries of the pipeline. The detection of defects is indicated by reflected ultrasound due to cross-section change. The technology is widely used for offline inspection to monitor corrosion type defects as is limited to operate at ambient temperatures. To enable SHM of HT pipework, a HT-UGW system was developed using HT transducers and collar for permanent attachment. Ultrasonic response of the HT transducer is highly sensitive to temperature variations and over time, which may lead to false alarms. Initially, a long term laboratory experiment was performed to evaluate effect of temperature on the system and its monitoring capabilities. The system showed a stable thermal response and could detect 2% cross-section change at HT. The system was then installed on a pipe operating at up to 200°C for over 1 year and the in-service UGW (T (0,1) wave mode in 4060kHz range) data is analysed to investigate the effect of temperature loading and temperature over time on the system performance. The findings from this work increases confidence in UGW technique for HT-SHM and will contribute in the development of enhanced temperature compensation for improved defect detection under varying temperature ranges.