硫化氢环境下老旧管道失效概率评价方法研究

Researchon Failure Probability Evaluation Method of Old Pipelinein Hydrogen Sulfide Environment

老旧管道在服役过程中存在着失效风险,而影响老旧管道失效的因素有很多,在众多影响因素中硫化氢对管道产生的腐蚀损伤较严重。为解决受腐蚀损伤的老旧管道安全评估问题,文章建立了一种在硫化氢环境下老旧管道失效概率评价方法。以在硫化氢环境中使用了约20年的老旧集气管道为研究对象,采用蒙特卡洛法模拟管道服役过程中的动态压力和腐蚀损伤引起的剩余强度的变化,计算了单一腐蚀因素引起管道失效的概率,并通过正态分布概率给出管道使用的安全范围。研究结果表明:投运20年以上的含硫老旧管道在氢致开裂实验与应力腐蚀开裂实验中,均未发生开裂。根据模型计算得出,老旧管道依旧可以安全服役,但服役6年后失效概率超过0.5,需要进行整修工作,服役27年后,管道内腐蚀严重,剩余强度降到3.82 MPa,需要更换管道。通过模拟得到了失效概率与腐蚀缺陷和服役时间的关系,为老旧集气管道再服役提供理论依据和参考价值。

There are failure risks in the service process of old pipelines,and there are many factors affecting the failure of old pipelines.Among the many influencing factors,hydrogen sulfide can cause serious corrosion damage to the pipeline.In order to solve the problem of safety assessment of old pipelines damaged by corrosion,a novel failure probability evaluation method for old pipelines in hydrogen sulfide environment is established in this paper.Taking the old gas gathering pipeline used in hydrogen sulfide environment for about 20 years as the research object,the Monte Carlo method is used to simulate the dynamic pressure change and the reduction of residual strength caused by corrosion damage during the service of the pipeline.The probability of pipeline failure caused by a single corrosion factor is calculated,and the safety range of pipeline usage is given by the normal distribution probability.The results show that the old sulfur-containing pipeline which has been put into operation for more than 20 years has not cracked in the hydrogen-induced cracking experiment and the stress corrosion cracking experiment.According to the model calculation,the old pipeline can still serve safely,but the failure is more than 0.5 after 6 years of service,and the renovation work is needed.After 27 years of service,the corrosion in the pipeline is serious,and the residual strength is reduced to 3.82 MPa,so the pipeline needs to be replaced.The relationship between failure probability and corrosion defects and service time is obtained by simulation,which provides theoretical basis and reference value for the re-service of old gas gathering pipelines.