埋地管道外腐蚀两阶段模型及其剩余寿命预测

Two-stage Model and Residual Lifetime Prediction of Buried Pipeline Subjected to Corrosion

传统的埋地管道腐蚀生长过程模型一般将管道从投入使用到检测时刻的持续时间作为腐蚀时间,认为管道从投用即开始腐蚀。埋地管道通常采用外防腐层和阴极保护等措施以减缓腐蚀,当防腐层破坏后管体金属才会腐蚀。基于实际的腐蚀过程,将埋地管道的腐蚀过程分为两个阶段:1管道防腐层失效阶段,该阶段管体本身不发生腐蚀。2管道腐蚀且腐蚀缺陷扩展的阶段。应用线性腐蚀生长模型对腐蚀缺陷的扩展过程进行了建模,利用检测数据对模型进行了参数估计,通过对预测腐蚀深度分布与实际腐蚀深度分布结果比较后发现,两阶段模型比传统的一阶段模型具有更好的拟合效果,在此基础上,运用Monte Carlo仿真方法对实际的管道剩余寿命做出了预测。

The conventional corrosion growth models of buried pipeline generally considered that pipeline started to be corroded when it come into service.But buried pipeline always requires some protective measures（e.g.coating and catholic protection）to prevent corrosion.It requires aperiod for the failure of these protective measures.The corrosion process of buried pipeline is divided into two stages.The first stage is the failure process of protective measures,during which pipeline can’t be corroded.In the second stage,pipeline corrosion begins,defects appear and expand.The linear growth corrosion model has been used to model the expanding process of corrosion defects,and the actual distribution of corrosion depth has been used to estimate parameters of this model.The data at the first detection time are used to predict the distribution at the second detection time.The predictive result shows the two-stage model makes a better fitness to the actual distribution than the traditional one-stage models.Based on the two-stage model,the Monte Carlo simulation method is used to predict residual lifetime of buried pipeline.