集输管道腐蚀缺陷非开挖评价方法研究

Study on trenchless evaluation method for corrosion defects of gathering pipeline

为省去开挖取样步骤,以提升腐蚀缺陷检测过程的安全性与经济性,建立了一种集输管道腐蚀缺陷的非开挖评价方法。利用ANSYS软件进行有限元分析,结合铁磁学相关理论建立集输管道腐蚀缺陷磁信号模型;分析腐蚀缺陷影响参数对磁感应强度梯度模量的影响;综合模型与GB/T 35090—2018《无损检测管道弱磁检测方法》,建立该评价方法,并在新疆油田某管道进行了工程验证。结果表明,该方法计算出的腐蚀缺陷综合评价指数F与实际开挖后检测得出的腐蚀缺陷综合评价指数F绝对误差分别为-0.02和-0.01,相对误差分别为-3.13%和-1.61%。该评价方法较现有腐蚀缺陷评价方法可省略开挖取样点步骤,使检测过程更加安全、经济、环保。

To eliminate the excavation sampling step and improve the safety and economy of the corrosion defect detection process,a trenchless evaluation method for corrosion defects of gathering and transportation pipelines was established.Using ANSYS software to carry out the finite element static analysis on the corrosion defect,the stress distribution on the surface of the corrosion defect is obtained,and the magnetic signal model of the corrosion defect of gathering and transportation pipeline is established based on the theory of ferromagnetism.Combined with this model and the surface stress distribution of corrosion defects obtained by finite element static analysis,the gradient modulus of magnetic induction intensity at the corrosion defects of buried gathering and transportation pipelines under different pipelines,corrosion size parameters,and internal pressures can be calculated.The influences of corrosion defect depth,length,and width on the gradient modulus of magnetic induction intensity under certain internal pressure and pipe size parameters were analyzed by this model.Integrating magnetic signal model of corrosion defects and GB/T 35090—2018 nondestructive testing pipe weak magnetic detection method and establishing the trenchless evaluation method of pipeline corrosion defects can obtain direct use the detected magnetic signals on the data of the buried pipeline corrosion defects.The developed method was verified by using one pipeline in the Xinjiang oilfield.The results show that:Through trenchless evaluation method for corrosion defects of gathering and transportation pipelines,the comprehensive evaluation index F value of corrosion defects was obtained by using magnetic signal data detected on site.Compared with the comprehensive evaluation index F value of corrosion defects obtained by conventional detection method after actual excavation,the absolute error was-0.02 and-0.01,and the relative error was-3.13%and-1.61%,respectively.Therefore,the trenchless evaluation method for corrosion defects of gathering and transportation pipelines established in this paper is of great significance for trenchless evaluation of corrosion defects of gathering and transportation pipelines.Compared with existing evaluation methods for corrosion defects,the steps of excavation sampling points can be omitted,making the inspection process safer,more economical and more environmentally friendly.