Abstract: In order to study the local mechanical properties of pipeline's defects, taking X70 pipeline as the research object, based on the knowledge of elasticplastic mechanics, ANSYS is applied to simulate the distribution near defects of Von Mises stress and plastic strain under the action of high temperature. Then the variation tendency of the maximum stress and plastic strain of key parts near defects with the increase of internal pressure is analyzed. Also, the variation trend of the maximum Von Mises stress with the corrosion depth under the specific operating pressure is discussed. Finally, the Von Mises stress distribution and variation considering and without considering the temperature expansion are compared. The results show that there is a greater stress along the circumferential direction in the corrosion zone at high temperature. With the increase of internal pressure, the maximum Von Mises stress decreases first and then increases, and the greater stress also becomes axial distribution. ASME B31G1984,ASME B31G1991,PCORRC and DNVRPF101 methods are still suitable for evaluating the residual strength of pipelines under high temperature. 

Key words: Natural gas pipeline, Defect, Von Mises stress, Von Mises plastic strain

摘要： 为研究高温下含缺陷管道的局部力学特性,以X70管道为研究对象,基于弹塑性力学知识,利用 ANSYS模拟其在高温作用下缺陷局部的等效应力分布;并分析了高温下缺陷局部的最大等效应力、塑性应变随内压的变化趋势;进一步讨论了在特定运行压力下最大等效应力随腐蚀深度的变化趋势;最后对比了失效压力下是否考虑热膨胀影响的等效应力分布及变化。结果表明,仅有高温时,腐蚀区内沿环向分布有较大应力;随着内压的增加,最大等效应力先减后增,较大应力也变为沿轴向分布;温度达到一定值后,缺陷越深,其对管道剩余强度的影响越大;高温作用下ASMEB31G1984、ASMEB31G1991、PCORRC、DNVRPF101等方法仍适用于对含椭球型缺陷管道进行剩余强度的评估。

关键词: 天然气管道, 缺陷, 等效应力, 等效塑性应变