油气管道环焊缝非开挖定位弱磁检测技术研究

Weak magnetic detection technology for trenchless positioning of oil and gas pipeline girth welds

介绍了非接触式管道弱磁检测技术的原理,并针对实际工程采用非接触式管道弱磁检测仪对油气长输管道环焊缝进行非开挖定位及检测。具体的弱磁检测过程主要分为3个步骤:(1)利用管线探测仪对管道走向和管道埋深进行测绘;(2)采用载波相位分差技术确定管道的位置坐标(GPS坐标);(3)使用弱磁检测仪在管道正上方对其磁场分布进行信号采集。对磁信号图像进行滤波处理,根据磁感应强度沿法向变化量梯度DB_(z)过零点且改变符号,而磁感应强度沿切向变化量梯度DB_(y)出现波峰或波谷的特征来判断特征点处存在环焊缝。通过特征点到里程桩的相对距离与内检测所得管道信息对比,可以得到环焊缝的建设期编号且误差通常小于1 m。其次根据检测段管道的起点终点GPS坐标可以计算出任意特征点的GPS坐标,从而得出环焊缝的具体地理位置,为后续管道本体的修复以及定位开挖提供技术支持。

This paper introduces the principle of weak magnetic detection technology of non-contact pipeline,and uses non-contact pipeline weak magnetic detector for the actual engineering to carry out non-excavation positioning and detection of the ring weld of the oil and gas long pipeline.The specific weak magnetic detection process is divided into three steps:(1)The pipeline detector is used to detect the pipeline direction and pipeline depth mapping.(2)The location coordinates(GPS coordinates) of the pipeline are determined by carrier phase difference technology.(3)The magnetic field distribution of the magnetic field is collected with a weak magnetic detector directly above the pipe.The magnetic signal image is filtered and processed,and the characteristics of the characteristics of the characteristic stomp or trough are judged to be present at the feature point according to the change gradient DB_(z) crossing zero and the symbol change sending the symbol along the change gradient of the change DB_(y) in the tangential change.By comparing the relative distance between the feature point and the mileage pile with the pipe information obtained by the internal detection,the construction period number of the ring weld can be obtained and the error is usually less than 1 m.Secondly,the GPS coordinates of any feature point can be calculated according to the starting point and the end point of the detection segment pipeline so as to get the specific geographical location of the ring weld,and provide technical support for the repair of the subsequent pipe body and the location excavation.