摘要
为了确定石油天然气输送管道能否在规定的管道压力下正常运行,避免油气管道发生安全事故,必须对含体积型缺陷的管道进行剩余强度评价。以断裂力学和工程实践经验相结合的半经验公式作为含体积型缺陷管道进行剩余强度评价的标准已经被国内外所广泛采用。为此分析研究了ASME B31G-2012标准的3种流变应力计算方法,得出各管线钢在选用不同方式计算流变应力时,管道剩余强度值之间所存在的差异,剩余强度评价结果也会存在着不同的保守性。进而计算了不同条件下安全系数的选取范围,讨论了地区等级变化对安全系数的影响程度;并针对ASME B31G-2012标准比较了原剩余强度计算公式和改进后的剩余强度计算公式,认为改进后公式通过改变鼓胀系数和缺陷投影面积降低了剩余强度评价结果的保守性;最后通过实际工程运用明确了流变应力、安全系数、剩余强度计算公式的选取原则。结论认为:在实际应用中需要综合考虑管道使用年限、管材性质、缺陷特征、所处地区等级、检测技术及业主要求等多方面的因素来确定如何选取评价管道剩余强度的相关参数。
Accidents of oil and gas pipelines can be avoided if safe and normal functioning of the pipelines under the stipulated pressure is guaranteed, so it is necessary to evaluate the residual strength of the pipelines with volumetric defects. The semi-empirical formula which combines fracturing mechanics with practical engineering experience is widely used around the world as the standard for the re- sidual strength evaluation of pipelines with volumetric defects. In this paper, three calculation methods of flow stress presented in ASME B31G-2012 were analyzed and studied. According to the results, when the flow stress of pipeline steels is calculated by using different methods, the calculated residual strength of pipelines is different and its conservative degree of evaluation results is also different. Then, the value range of safety factor under different conditions was calculated and the effect of location class change on the safety factor was discussed. As per the ASME B31G-2012, the original residual strength formula was compared with the improved one. It is shown that the conservative degree of residual strength evaluation results is decreased by changing the expansion coefficient and the defect projection area after the formula is improved. Finally, the selection principles on the calculation formula of flow stress, safety factor and residual strength were confirmed in reference to actual projects. As for actual application, it is recommended to analyze multiple factors compre- hensively （e.g. pipeline service life, pipe material properties, defect characteristics, local rating, detection technologies and clients＇ re- quirements） so as to select the correct parameters for the residual strength evaluation of pipelines.
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2016年第5期115-121,共7页
Natural Gas Industry
