长输管道凹陷提压回圆评价方法

Evaluation method of rerounding by pressure increase for dent on long-distance pipeline

为了解决长输管道深凹陷所导致的清管器及内检测器难以通过的工程问题,基于局部提高管道内压可使凹陷回圆、深度减小以达到清管器或检测器可通过深度门槛值的思想,建立了内压作用下管道凹陷回圆过程非线性有限元模型;提出了管道凹陷回圆系数的定义;通过应力应变响应分析对凹陷回圆过程的安全性进行论证;对回圆系数的影响因素进行分析,探讨径厚比、管材、凹陷尺寸、初始内压、回圆压力等参数对回圆系数的影响;基于有限元计算算例,采用非线性回归的方法拟合了凹陷回圆系数工程计算公式。研究结果表明:在极限回圆压力工况下,凹陷回圆过程中管道未发生二次塑性损伤;误差分析显示拟合所得公式预测精度较好,可用于长输管道凹陷的回圆评价。

In order to solve the engineering problem about the difficult passage of pigging device and internal detector caused by the deep dent of long-distance pipeline,based on the idea that locally increasing the internal pressure of pipeline can make the dent rerounding and reduce the dent depth to a threshold value that the pigging device or detector can pass through,a nonlinear finite element model for the process of pipeline’s dent rerounding under the internal pressure was established.The definition of pipeline’s dent rerounding coefficient was put forward,and the safety of the dent rerounding process was demonstrated by the stress-strain response analysis.The factors affecting the rerounding coefficient were analyzed,and the influence of parameters such as diameter-thickness ratio,pipe material,dent size,initial internal pressure and rerounding pressure on the rerounding coefficient were discussed.Based on the finite element calculation example,the engineering calculation formula of the dent rerounding coefficient was fitted by the nonlinear regression method.The results showed that no secondary plastic damage occurred in the pipeline during the dent rerounding process.The error analysis showed that the fitted formula had good prediction accuracy,and it can be used for the rerounding evaluation of dent on the long-distance pipeline.