清管载荷作用下输气管道安全落差研究

山地天然气管道局部落差和坡度大,在清管过程中易在清管器冲击载荷作用下发生屈曲和应力超限。基于有限元方法研究了考虑管-土耦合作用的大落差管段清管过程非线性动力学特征,分析了清管器运行速度、管道坡度、清管器-管内壁间摩擦系数对管道受力和位移的影响,得到了不同坡度、摩擦系数条件下极限清管运行速度和最大高程差。结果表明:清管器运行速度、管道坡度的增加会引起管道应力、位移的增加,运行速度的影响效果更为显著;随着清管器-管内壁间摩擦系数的增加,清管冲击载荷先减小后增加;针对Φ813mm×11mm的X70输气管道,在管道坡度为30°~70°、落差不超过340m~691m范围内的清管作业是安全的。

Study on safe elevation difference of gas pipeline under the pigging impact conditions

Mountain natural gas pipelines have high elevation difference and large slopes, which are prone to buckle and stress overruns during pigging under the impact of pig impactors. Based on the finite element method, the non-linear dynamic characteristics of the large-drop pipe section pigging process considering the pipe-soil coupling effect are studied. The influences of the slope of the pipe, the coefficient of friction between the pig and the inner wall of the pipe, and the operating speed of the pig to the force and displacement of the pipe are analyzed. The limit pigging speed and maximum elevation difference under different slopes and friction coefficients are obtained. The results show that:(1) the increase of pigging speed results in the increase of pigging load, which is more significant than that of pipeline slope;(2) the effects of pig inner wall friction coefficient on the impact load is not a single linear change, which shows a trend of decreasing first and then increasing;(3) for the Φ813′ 11 mm(X70) gas transmission pipeline, the pigging operation with a drop of no more than 340 m-691 m is safe for pipeline slop within the range of 30°-70°. It provides a reference for the selection of laying mode of mountain pipeline through slope and ditch reach.