复合板压力容器点腐蚀缺陷运行适应性评价

Fitness-for-Service Assessment of the Composite Plate Pressure Vessel Containing Pitting Defects

为准确反映含点腐蚀缺陷复合板压力容器的安全状态,在复合结构弹性力学分析的基础上,通过工程实例,采用运行适应性(FFS)评价方法对其进行安全评定与剩余寿命评估。结果表明:复合板压力容器安全评定时应考虑覆材的影响,依据提出的力学模型分别对覆材厚度计入和不计入强度设计2种情况进行应力校核,同时结合蚀孔的分布特征,对其特征尺寸进行统计学平均后计算剩余强度。在剩余寿命预测中,已考虑蚀孔直径和深度随时间变化对剩余强度的影响。通过计算最大工作压力(MAWP)参量,已对某一压力容器进行寿命评估。

In order to accurately reflect the safety situation of composite plate pressure vessel containing pitting defects, FFS method was applied to safety assessment and remaining life based on elastic mechanics analysis of composite structure. The results show that the influence of cladding metal should be considered in safety assessment, and that the proposed mechanical model can be used for strength check regardless of the cladding metal thickness included in the strength design. According to distribution characteristics of the pits, remaining strength can be calculated after statistical averaging of the characteristic parameters of the pits. In predicting the remaining strength, it was taken into account that changes in pit diameter and depth with time influence remaining strength. The remaining life of a certain pressure vessel was evaluated by calculating the maximum working pressure （MAWP）.