油气管道不等壁厚环焊缝坡口形式改进

Improving groove forms of girth welds of unequal wall thickness in oil and gas pipelines

近年来,中国发生多起油气管道环焊缝失效事故,已引起国内外管道行业的高度重视。统计分析油气管道环焊缝失效案例,针对失效事故中占比较大的不等壁厚环焊缝失效进行原因分析,提出了不等壁厚环焊缝内坡口改进建议。以西气东输西四线(吐鲁番—中卫)某直径1 422 mm天然气管道工程为例,基于焊接、无损检测、坡口加工、内检测、应力集中5项原则,设计了直管与热煨弯管对接的不等壁厚环焊缝孔锥形内坡口方案,并对比分析了坡口的强度。研究结果可为提高不等壁厚环焊缝的焊接质量、提升管道本质安全提供参考。

In recent years,several failure accidents of girth welds occurred in oil and gas pipelines in China,drawing increasing attention from domestic and foreign pipeline industries.Herein,the cases of girth weld failure of oil and gas pipelines were summarized and analyzed.On this basis,the causes for the failure of girth welds with unequal wall thickness,taking a larger proportion in the failure accidents,were analyzed,and suggestions were put forward for the counterbore-tapered grooves of girth welds with unequal wall thickness.Under the background of a natural gas pipeline with a diameter of 1422 mm in the Fourth Line of the West-to-East Gas Pipeline(Turpan-Zhongwei),the counterbore-tapered groove scheme of girth welds with unequal wall thickness was designed for the joining of straight pipelines with the hot-bending bends based on the 5 principles of welding,nondestructive testing,groove processing,internal inspection,and stress concentration.Meanwhile,the strength of grooves was analyzed comparatively.The research results could provide a reference for improving the welding quality of girth welds with unequal wall thickness and the intrinsic safety of pipelines.