Analysis of leakage in high pressure pipe using acoustic emission method
Analysis of leakage in high pressure pipe using acoustic emission method
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DOI：
10.1016/j.apacoust.2012.07.012
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发表时间：
2013-03-01
影响因子：
3.4
通讯作者：
Davoudi, S.
中科院分区：
文献类型：
--
作者：
Mostafapour, A.;Davoudi, S.
泄漏检测是石油和天然气管道中最重要的问题之一，因为它会导致经济损失，以及严重的人类和环境影响。声发射检测是一种新的泄漏检测技术。高压管道的泄漏会产生局部能量损失引起的应力波。应力波通过管壁传播，可通过安装在管壁上的声学传感器或加速度计进行记录。了解泄漏引起的声发射如何使管壁振动是检测和定位泄漏的关键参数。本文旨在对管道泄漏振动产生的声发射进行建模。利用Donnell的圆柱壳非线性理论，推导了简支边界条件下的运动方程。然后用Galerkin法求解运动方程，得到了6个自由度的非线性方程组。来解决这些非线性方程。利用MatLab软件中的ODE工具和龙格-库塔数值方法计算管壁的径向位移。为了验证该方法的有效性，测量了连续泄漏源的声发射。采用ASTM A 106/99系列传感器对标称长度为6m、壁厚为7.35 mm、外径为169 mm的钢管进行了试验。加压后的空气通过压缩机进入管道内。在5bar气压下，使用两个直径分别为0.6 mm和1 mm的模拟连续泄漏源。该震源传播的波的频率很大，约为0-400千赫。在这项研究中，使用的声发射传感器的共振频率分别接近150和300 kHz，对管道的振动行为进行了研究。利用声发射传感器记录了管壁振动产生的信号。在下一步中，使用快速傅立叶变换(FFT)对信号进行分析。对所得结果的比较表明，实验频率范围与模型频率范围符合得很好。分析模型与实验结果的平均误差小于6%。(C)2012爱思唯尔有限公司。保留所有权利。
Leak detection is one of the most important issues in the oil and gas pipelines, as it can lead to financial losses, as well as severe human and environmental impacts. Acoustic emission test is a new technique for leak detection. Leakage in high pressure pipes creates stress waves caused by localized loss of energy. Stress waves are transmitted through the pipe wall which can be recorded by using acoustic sensor or accelerometer installed on the pipe wall. Knowledge of how the pipe wall is vibrated by acoustic emission resulting from leakage is a key parameter for leak detection and localization. This paper aims to model acoustic emission generated by pipe vibration due to leakage. Donnell's non-linear theory for cylindrical shell was used to derive motion equation under simply supported boundary condition. Then, the motion equation was solved by using Galerkin method that resulted in a system of non-linear equations with 6 degrees of freedom. To solve these non-linear equations. ODE tool of MATLAB software and Runge-Kutta numerical method was employed to obtain pipe wall radial displacement. For verifying this method, acoustic emission by a continuous leak source was measured. Experiments were carried out with a linear array of sensors on steel pipe (ASTM A 106/99) of nominal length 6 m, 7.35 mm wall thickness and external diameter of 169 mm. The pressurized air was flown inside the pipe through the compressor. Two simulated continues leak sources with 0.6-mm and 1-mm diameter holes were used under 5 bar air pressure. This source propagated waves in a large of frequencies about 0-400 kHz. In this study the vibration behavior of the pipe is investigated per resonance frequencies of the used AE sensors which are near 150 and 300 kHz. Signals generated by the pipe wall vibration were recorded by using acoustic emission sensors. In the next step, Fast Fourier Transform (FFT) was used in the signal analysis. Comparison of the obtained results, indicate the good agreement between the experimental and modeled frequencies ranges. The mean error between analytical modeling and experimental results is less than 6%. (C) 2012 Elsevier Ltd. All rights reserved.