基于超声导波的管道缺陷监测及径向损伤评估

Defect Monitoring and Radial Damage Evaluation of Pipeline Based on Ultrasonic Guided Wave

管道缺陷监测及径向损伤评估对于油气管道安全运行具有重要意义。为了提高超声导波对油气管道缺陷的监测能力,提出了一种根据L(0,2)和L(0,1)模态导波的变化趋势实现径向损伤深度评估的新方法。采用单通道激励-接收装置以多次叠加合成的方式实现了时间反转法,使导波能量在油气管道缺陷处聚焦,增强缺陷反射回波幅值,提高监测信号的信噪比。通过具体试验证明了采用合成时间反转法提高超声导波对油气管道缺陷监测能力的有效性。L(0,2)模态导波在管道中传播时遇到缺陷会发生模态转换,部分L(0,2)模态会转换为L(0,1)模态。结合导波在管壁中的位移分布,分析了管道缺陷径向损伤深度对L(0,2)到L(0,1)模态转换的影响。试验数据表明,随着管道缺陷径向损伤的扩展,L(0,2)和L(0,1)模态缺陷反射系数呈现出有规律的变化。研究结果为评估管道缺陷径向损伤深度,判断其是否达到半壁厚或贯穿程度提供了重要参考。

The defect monitoring and radial damage evaluation are of great significance for safe operation of oil and gas pipelines.In order to improve the monitoring ability of ultrasonic guided waves for pipeline defects,a new method for radial damage depth evaluation based on the variation trend of guided waves in L(0,2)and L(0,1)modes was proposed.The single-channel exciting-receiving device was used to realize the time reversal method in the way of multiple superimposition synthesis,allow the guided wave energy to be focused at the pipeline defect,enhance the reflection echo amplitude of the defect,and improve the signal to noise ratio of the monitoring signal.The effectiveness of using synthetic time reversal method to improve the ability of ultrasonic guided wave to monitor pipeline defects was proved by specific tests.When the L(0,2)mode guided wave propagated in the pipeline,the mode would convert while encountering defect,and some L(0,2)modes were converted to L(0,1)modes.Combined with the displacement distribution of guided wave in the pipe wall,the influence of the radial damage depth of pipeline defect on the mode conversion from L(0,2)to L(0,1)was analyzed.The test data show that,as the radial damage of pipeline expanded,the reflection coefficients of L(0,2)and L(0,1)modal defects showed regular changes.The study results provide an important reference for evaluating the radial damage depth of pipeline defects and judging whether it reaches half wall thickness or penetration.