核电站钢制安全壳底封头拼装方式与焊接变形控制
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摘要
核电站钢制安全壳底封头是国内核电行业首次采用的大尺寸、厚壁、多曲率、高精度花瓣椭球形焊接结构,并在现场组装、焊接。专用设备按不同曲率半径压制成型的钢板自身存在较大的残余应力,四圈钢板数量各不相同,导致各圈焊接收缩变形有所不同,预留焊接收缩间隙等较难控制,增加了组装难度,影响钢制安全壳底封头整体尺寸的控制,因此适宜的组装方式和焊接变形控制成为施工过程中的重要环节。从三种堆型的钢制安全壳底封头的两种拼装方式、焊接顺序以及焊接防变形工装、焊接工艺措施等方面着手进行分析研究,明确了两种拼焊方式均为可行,同时提出了自上而下的拼装方式的改进方向。
Containment vessel bottom head(CVBH),assembled and welded on nuclear power project sites,is a petal-shaped ellipsoidal structure featured by large size,thick walls,multiple curvatures,and high precision,which is adopted by China's nuclear power industry for the first time. The steel plate formed by special equipment through compression molding on the basis of different radii of curvature has large residual stress. Besides,the number of steel plates constituting each ring is different. These characteristics lead to different welding shrinkage and deformation for each ring and make it difficult to reserve a proper welding shrinkage gap. All these increase the difficulty of the assembling and greatly affect the control of the overall dimensions of the CVBH. Therefore,suitable assembly methods and welding deformation control become an important part of the construction process. This paper studies the two types of assembly,welding sequence,anti-deformation welding fixtures,welding processes and other measures of CVBH in three types of nuclear power reactors. Through such introduction and analysis,this paper has validated that the two types of assembly are both feasible and proposed the direction of improvement for the top-down assembly method.
Containment vessel bottom head(CVBH),assembled and welded on nuclear power project sites,is a petal-shaped ellipsoidal structure featured by large size,thick walls,multiple curvatures,and high precision,which is adopted by China's nuclear power industry for the first time. The steel plate formed by special equipment through compression molding on the basis of different radii of curvature has large residual stress. Besides,the number of steel plates constituting each ring is different. These characteristics lead to different welding shrinkage and deformation for each ring and make it difficult to reserve a proper welding shrinkage gap. All these increase the difficulty of the assembling and greatly affect the control of the overall dimensions of the CVBH. Therefore,suitable assembly methods and welding deformation control become an important part of the construction process. This paper studies the two types of assembly,welding sequence,anti-deformation welding fixtures,welding processes and other measures of CVBH in three types of nuclear power reactors. Through such introduction and analysis,this paper has validated that the two types of assembly are both feasible and proposed the direction of improvement for the top-down assembly method.
引文
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[2]ASME.Boiler&Pressure Vessel Code section III D1 NE.核设施部件建造规则,第1册NE分卷[M].上海:上海科学技术文献出版社,2004:123-131.
[3]中国机械工程学会焊接学会编.焊接手册第3卷:焊接结构(第2版)[M].北京:机械工业出版社,2001:1009-1026.
[4]陆皓,陈俊梅,刘俊,等.大型筒体结构焊接变形预测理论与应用[A].2005能源工程焊接国际论坛[C].2005:122-126.
[5]许旭东,李光俊.控制不锈钢筒体焊接变形工艺[A].2004探索创新交流---中国航空学会青年科技论坛文集[C].2004:601-608.
[6]中国机械工程学会焊接学会编.焊接手册第2卷:材料的焊接(第2版)[M].北京:机械工业出版社,2001:258-270.
[7]樊兆宝,刘凤祥,安绍孔,等.解决筒体对接圆周焊缝热影响区凹陷变形的工艺方法研究[J].航空精密制造技术,2009,45(6):41-44.
[8]杨松,樊险峰,李世魁,等.锅炉压力容器焊接技术培训教材[M].北京:机械出版社,2005:319-323.