埋地输油管道的断裂失效概率评估

ASSESSMENT ON FRACTURE FAILURE PROBABILITY OF BURIED PIPELINES

利用Monte Carlo模拟方法编制了断裂失效概率的计算程序 ,并对某输油管道进行了实例计算。计算结果表明 ,R6通用曲线、R6附录 8的C Mn曲线、CVDA 84压力容器缺陷评定规范和KI 因子等 4种断裂判据在服役初期的差别微小 ,但在服役后期 ,它们之间的差别增大。在所有的参数中 ,初始裂纹深度、断裂韧性、流变应力和管道壁厚等参数对管道断裂失效概率的影响最大 ,选定的概率分布类型对失效概率的计算结果也有影响。利用水压试验方法可以明显地降低管道在运行时的断裂失效概率。

By means of Monte Carlo simulation, a computer program named as BPFA (Buried Pipeline Failure Analysis) is developed and applied to compute failure probability related to various kinds of random factors. As examples, the actual analyses about an oil pipeline are given. The results demonstrate that the difference of assessment using R6 general curve, C Mn curve in R6 appendix 8, CVDA 84 specification for pressure vessel and K I factor theory is small in the early stage of service, and it becomes larger in the late stage. Among all the parameters, initial defect depth, fracture toughness, flow stress, and pipe thickness have significant effects on the failure probability. The assigned styles of distribution of parameters have also effects on the failure probability. Proof test with water pressure could greatly reduce the failure probability of pipelines in service.