基于广义极值分布的点蚀管道剩余寿命预测及案例分析

Residual life prediction and case analysis of pitting pipeline based on generalized extreme value distribution

为了预测点蚀管道的剩余寿命,在对老龄管道腐蚀失效段的腐蚀深度进行拟合统计分析的基础上,建立广义极值分布函数,采用改进的人工鱼群算法(IASFA)优化模型参数,并利用估计结果预测整条管道最大腐蚀深度,基于可靠度理论预测了管道剩余寿命,并进行了案例分析和算法对比。结果表明,不同服役年限下腐蚀深度符合的概率分布函数不同,Gumbel分布、Frechet分布和Weibull分布的拟合优度较好,其余模型的拟合效果较差,仅用一种模型表征腐蚀状况具有局限性;通过案例分析,广义极值分布法、有限折线近似法、常规剩余寿命预测法计算的管道设计寿命分别为30.96、23.87、20.77 a,剩余寿命分别为14.96、7.87、4.77 a,广义极值分布法的计算结果与实际设计寿命一致,预测模型不受数据分布限制,其结果具有实际的指导意义。

In order to predict the residual life of pitting pipelines,the corrosion depth of the corrosion failure section of the old pipeline is fitted and analyzed,and the generalized extreme value distribution function is established.The improved artificial fish swarm algorithm(IASFA)is adopted to optimize the model parameters,and the maximum corrosion depth of the whole pipeline is predicted by using the estimated results.Based on the reliability theory,the residual life of the pipeline is predicted.The case analysis and algorithm comparison are carried out.The results show that the probability distribution functions corresponding to the corrosion depth under different service life are different,among which the goodness of fit of Gumbel distribution,Frechet distribution,and Weibull distribution is great,while that of other models is poor.This thus proves the limitation of using only one model to characterize corrosion conditions.Through case analysis,the design life of the pipeline calculated by the generalized extreme value distribution method,the finite broken line approximation method,and the conventional residual life prediction method is 30.96 a,23.87 a,and 20.77 a,respectively,and the residual life is 14.96 a,7.87 a,and 4.77 a,respectively.The results of the generalized extreme value distribution method are consistent with the actual design life.The prediction model is not restricted by the data distribution,and the results have practical guiding significance.