基于有限元法分析双层海底管道断裂失效问题

Subsea Pipe-in-Pipe Fracture Failure Problem Based on Finite Element Method

针对南海某油田平台间某双层海底管道的外管发生一处断裂失效事故,根据管道实际运行工况,考虑土壤摩擦力对外管的作用,利用有限元接触分析方法进行双层海管的受力分析,结合DNV规范对管道进行强度校核。结果显示:利用有限元接触算法来分析管土相互作用时,采用刚性面来模拟土壤层是可行的;在未超过原设计压力和设计温度条件下,该海管的外管将不会发生断裂失效事故,管道满足结构强度要求;若海管产生较严重的局部腐蚀,最严重腐蚀点的缺陷凹坑深度超过壁厚的85%,将会发生断裂失效事故。

Aiming that the fracture failure of the outer pipe of subsea pipe-in-pipe between a oil field from the South China Sea was occurred, and according to the actual operational states of pipeline, considering the soil friction on outerpipe, the finite element analysis method was used to analyze stress of subsea pipe-in-pipe, and the pipe intensity check was done combining with DNV. The results show that it is feasible that the rigid surface was used to simulate the soil layer when the contact analysis of the finite element is used to calculate pipe-soil interaction. Not excess of the original design pressure and temperature conditions, the outside of the sea pipe can not occur fracture failure accident, pipe satisfies the requirement of structure strength. If the sea tube produces serious localized corrosion, the most serious corrosion point defect pit depth was by more than 85% of the wall thick- ness, fracture failure accidents will happen.