低频电磁波在管道内检测外定位的应用

油气长输管道的安全检测已越来越受到人们的重视。管道内检测是最重要的管道安全检测方法之一。扫描检测需要实时确定检测位置，并记录以备检测完成后从地面准确的定位管道腐蚀缺陷的位置，因此准确的进行检测定位是管道内检测的技术关键。笔者提出里程轮内定位、工艺点（焊缝）修正、外定位修正、转角定位四步综合检测定位方法。其中外定位修正通常采用低频电磁波定位的方法对管道内检测器的里程计数进行修正米提高定位的精度。通过建立管道内检测外定位的模型，推导出管道内磁场强度的计算公式。采用美国ANSYS软件对该模型进行仿真，仿真结果与实验数据相符合。这对进一步了解低频电磁波外定位技术有重要意义。

Application of Low-Frequency Electromagnetic Wave on Outer Orientation Problems in In-line Pipeline Inspection

In-line pipeline inspection is one of the most important ways for the safe inspection of pipeline. During scanning inspection it is needed to know the real-time locations and to record them in order to locate corrosions from the ground after the detection is completed. Therefore, the accurate orientation is the key technology to pipeline inspection. In this paper, the four-step comprehensive method, which contains course wheel orientation, welding lines modification, outer orientation modification and revolving angle orientation, was applied to locate pipeline corrosions. At the same time, for improving the precision, the orientation method with low-frequency electromagnetic wave is often used in outer orientation modification to modify the course wheel＇s count. By establishing the outer orientation model of in-line pipeline inspection, the formula to calculate the magnetic strength in the pipeline was derived, and ANSYS software was used to simulate the model. The simulation results are agree with the experimental data, the simulation results also show that different parameter values would affect the magnetic strength in the pipeline. This work is of great significance to understand the outer orientation technology with low-frequency electromagnetic waves.