【摘要】 工程管道会受到腐蚀,形成管壁局部变薄等缺陷,使承载能力降低。评定局部腐蚀缺陷所引起的管道承载能力降低对于确保管线的安全运行具有重要意义。现有的评价含缺陷管弯曲特性的NSC准则,将缺陷视为无限长,无从考虑缺陷长度的影响。改进的含缺陷管道抗弯准则采用了B31G的有效壁厚概念,以有效壁厚tcorr取代了NSC准则中的t,得到了包含缺陷长度的缺陷管极限弯矩新计算公式。本研究选用外径为73和114 mm的两种J55管线,在外表面预制了人工缺陷,通过三点弯曲对称加载试验对修正的含缺陷管道抗弯准则进行试验检验。结果表明,缺陷长度较小(L/Rt<1.5)时,试验结果与NSC标准相差较大,但与改进的含缺陷管道抗弯准则接近。缺陷的长度越大(L/Rt>3),试验结果与NSC准则和改进的NSC准则趋于一致。在本试验范围内管线直径对测试结果的变化规律无明显影响。更多还原

【Abstract】 In practical service,engineering pipelines suffer from corrosion,which affects the safety of pipeline.As to a local corroded pipeline,its wall becomes thinner locally and thus the capacity of bending load reduces.Therefore,the assessment of the bending limit moment for a pipeline with such locally corroded damage is important for safety assessment.In NSC（Net-Section Collapse Criterion）,the length of the defect is considered infinite,thus the length effect of local defects on the limit bending moment could not be taken into account.In the modified NSC,the effective wall thickness t_corr,which was proposed in B31G empirically,is introduced,thus a new formula is obtained.In the present research,artificially local thinning pipes of J55 steel are employed to perform 3-point bending experiments.The results show that,for shorter defect（L/Rt<1.5） the limit bending moment deviates from the NSC obviously,but agrees with the predictions of the modified NSC basically.For longer defect（LRt>3）,the limit bending moment agrees with both NSC and modified NSC.更多还原