西气东输二线X80钢管焊缝疲劳寿命分析

Analysis of fatigue life of welding seam of X80 steel pipe of the Line Two of West-East Natural Gas Transmission Project

输气管道运行过程中,输气量的变化会导致管道承受一定的波动压力,造成管道发生疲劳损伤,从而威胁管道的安全。通常在管材疲劳寿命测试和分析中尚未考虑置信度和安全概率的要求,不能完全满足管道可靠性评估的需要。为此,通过对管道焊缝材料进行疲劳实验,采用单边容限分析方法,同时考虑安全概率和置信度要求,建立了不同安全概率下西气东输二线X80钢管焊缝的疲劳寿命曲线;根据管道输气量不均匀系数,建立了管道的应力谱;在此基础上利用损伤累计原理评估了西气东输二线管道焊缝疲劳可靠性寿命。计算结果表明,在设计寿命周期内,西气东输二线管道不会发生疲劳破坏。该方法可以为管道疲劳寿命分析和可靠性评估提供依据,具有一定的工程应用价值。

During the operation of gas pipelines,the change of gas transmission volume will result in pressure fluctuation and the pipeline will suffer fatigue damage.The pipeline is accordingly in safety hazard.The confidence level and safety probability are normally not covered by the fatigue life test and analysis of the pipeline material,so the test can not meet the requirement of the pipeline reliability evaluation.Therefore,a fatigue test has been performed on the welding seam materials.The single-side tolerance analysis method has been adopted and the safety probability and confidence level have been considered.The fatigue life curve under different safety probability of the welding seam of the X80 steel pipe,which has been used in the Line Two,has been established.The stress spectrum of the pipeline has been established according to the non-uniformity coefficient of gas transmission volume.On this basis,the fatigue life reliability of the welding seam of the pipeline has been evaluated by the use of the cumulative damage theory.The results show that the line will not experience fatigue failure within the design life cycle.The method provides the basis for the pipeline fatigue life analysis and reliability assessment and is of certain engineering application value.