高钢级大口径天然气管道环焊缝安全提升设计关键

高钢级管道环焊缝失效事故屡见不鲜,随着高钢级管道里程不断增加,高钢级管道环焊缝失效问题引起国内外管道行业的高度重视。对国内外典型管道环焊缝失效案例进行归类分析,基于环焊缝断裂失效的断裂力学理论,针对影响环焊缝安全性的关键环节进行失效原因分析,并提出安全提升措施,包括管道焊接工艺、钢材控制、焊接材料、焊接接头强度匹配、不等壁厚内坡口形式、无损检测、智能巡检、应力应变、施工管理等。这些措施已经推广应用于中俄东线天然气管道工程及将建的西气东输三线中段管道工程、西气东输四线管道工程,为提升高钢级管道环焊缝的服役可靠性提供了支持。(图4,表9,参25)

Key factors for safety improvement design of girth weld in high-grade large diameter natural gas pipelines

Failure of girth welds in high-grade steel pipelines is common.With the surge in mileages of high-grade steel pipeline,the failure of girth weld in high-grade steel pipelines has drawn an increasing attention from domestic and foreign pipeline industries.The typical cases in China and abroad were classified and analyzed.Based on the fracture mechanics theory of girth weld fracture failure,the failure causes were analyzed for the key links that affect the safety of girth weld,and the safety improvement measures were hereby proposed,involving the pipeline welding technology,steel control,welding materials,strength matching of welded joints,internal groove types for unequal wall thickness,nondestructive testing,intelligent inspection,stress and strain,construction management,etc.These measures have been widely applied to the China–Russia Eastern Gas Pipeline Project,and are planned to be used in the middle section of the Line 3 and the Line 4 of West-to-East Gas Pipeline Projects which are to be built.Their practices are anticipated to provide support for improving the service reliability of girth weld in high-grade steel pipelines.(4 Figures,9 Tables,25 References)