含凹陷管道的完整性评价

针对凹陷引起的管道应力集中问题， 基于深度的评价准则已不能满足工程应用， 提出包含内检测、 噪声处理、 几何插值和应变求解的基于应变的评价流程。单纯凹陷对管道的剩余强度影响不大， 但与焊缝、 裂纹及划伤等其他种类缺陷联合作用时， 则可能加快管道的断裂失效， 可以采用弹塑性断裂理论对含裂纹和划伤凹陷进行剩余强度计算， 当凹陷位于焊缝时， 建议直接修复或替换。在内压波动影响下， 无约束凹陷的疲劳问题较为严重， 提出采用雨流计数法对管道的压力历程进行循环计数， 根据疲劳累积损伤理论确定管道的疲劳寿命或检修周期。通过对目前国外主要标准的分析和比较， 结合凹陷的自身特性， 提出了更加合理的管道凹陷完整性评价体系。

Integrity Assessment of Pipeline with Dents

The depth-based evaluation criteria have not been able to meet the engineering requirement concerningthe pipeline stress concentration caused by dent， so this paper proposes strain-based evaluation procedure composedof inline detection， noise treatment， geometric interpolation， and strain calculation. Plain dent has little influence onpipelineresidualstrength， butitmayacceleratepipelinefracturefailurewhencombinedwithweld， crack， scratches，and other defaults. The elastic-plastic fracture theory can be used for the strength evaluation， but when the dent isnear a weld， it must be repaired or replaced. Unconstrained dent faces the fatigue problem when internal pressurefluctuate. The fatigue life and maintenance period are predicted based on rainflow method and fatigue damagecumulative rule. According to the analysis and comparison of main standards and rules， this paper proposes acompletely integrity assessment system of pipeline dents.