长输管道不等厚焊缝应力集中分析

Stress Concentration of Unequal Thickness Welds in Long-Distance Pipeline

国内外对大口径、高钢级、高压力等级长输管道不等厚焊缝结构的研究相对较少。从应力集中的角度对管道不等厚焊缝结构进行受力分析,并通过计算得出不同结构参数变化对焊缝应力集中的影响程度。分析结果表明:采用有限元法和两点线性外插法计算管道不等厚焊缝的热点应力和应力集中系数,验证了模型的可行性;通过归一化处理后,可更加直观地对比焊缝不同结构参数对焊根处轴向应力和应力集中的影响;壁厚比对焊缝应力集中的影响远大于焊缝宽度、焊缝余高和焊缝过渡角,应重点关注高壁厚比结构的风险管段;管道不等厚焊缝处的应力集中在弯曲状态下将二次恶化,需及时管控此类风险。所得结论可为管道企业对长输管道的日常管理活动提供数据参考与风险警示。

Presently, there is few research on the unequal thickness welds in long-distance pipeline with large diameter, high steel grade and high pressure grade at home and abroad.In this paper, the unequal thickness welds were analyzed from the angle of stress concentration, and the influence degrees of different structural parameters on the weld stress concentration were calculated.The analysis results show that the calculations of the hot spot stress and stress concentration coefficient by using the finite element method and two-point linear extrapolation method verified the feasibility of the model.After normalization, the influences of different structural parameters of welds on the axial stress and stress concentration at weld root can be compared more visually.The pipeline sections with high wall thickness ratios should be paid more attention because the influence of wall thickness ratio on the weld stress concentration is much greater than that of weld width, weld reinforcement and weld transition angle.The stress concentration of unequal thickness welds will be worse in the bending state, and it is necessary to control such risks in time.The conclusions provide data reference and risk warning for the daily management activities of long-distance pipelines in the pipeline companies.