腐蚀管道剩余强度评价的基本方法

Methods for Assessment of Remaining Strength of Corroded Pipe

管道在长期的运行中不可避免会出现腐蚀,腐蚀缺陷的破裂是管道的主要失效形式。根据腐蚀管道的缺陷形貌将腐蚀分为均匀腐蚀、局部腐蚀和点蚀。采用双剪应力准则分析了腐蚀缺陷管道剩余强度的塑性极限承载能力,所建立的模型考虑了管道现场条件和室内爆破实验条件的差异,并提出了均匀腐蚀、局部腐蚀和点蚀管道剩余强度的分级评价方法和步骤,评价的精确性、评价所需数据资料的多少、评价人员的技能和完成评价分析的复杂性随级度的提高而增加。根据加拿大NOVA公司的爆破实验结果,可以验证该方法比美国ASMEB31G和API579所推荐的方法更为接近于工程实际。

The corrosion of pipe commonly appears during the pipe's long working time.The burst of corroded defects is the primary failure form of pipe.In the paper,the corrosion types was divided into general,local and pit corrosion according to defect's feature.The plastic limit carrying capacity of remaining strength of corroded pipe was analysed by use of twin shear stress criterion. The difference of condition between the local and the blast test of pipeline was considered in the model. Then, the methods and steps for graded assessment of remaining strength of pipe with general or local or pit defect was advanced respectively.Each assessment level provides a balance between conservation,the amount of information required for the evaluation, the skill of the personnel performing the assessment, and the complexity of analysis being performed.In terms of results of blast test of pipe conducted in NOVA company of Canada,the mothod is more close to engineering practice than the recommended practice in the ASME B31G and the API579 of America.