水电站的机组分期组装,在管道无闸阀的情况下,需在管道末端设置临时性封堵头。厂房施工安装为防止尾水倒灌,钢管和蜗壳试压以及预留发电支洞等,也都需要设置封堵头。壳体结构最理想的几何形状,应是双曲率壳体为最好。但这种形状,一般加工工艺难以达到所要求的外形。因此,一般水电工程上, Hydropower units staged assembly, in the case of pipe gate valve, the need to set temporary plug in the end of the pipeline. Plant construction and installation In order to prevent tail water intrusion, steel pipe and volute pressure test and reserve generating branch hole, also need to set plugging head. The best geometry of the shell structure should be the best double-curvature shell. However, this shape, the general processing technology is difficult to achieve the desired shape. Therefore, the general hydropower project,