关键词: 天然气管道, 缺陷, 等效应力, 等效塑性应变

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