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近几年来,下向焊已在实践中被绝大多数焊工掌握,并积累了一定的施焊经验。但在管道建设工程中,由于应用的时间尚短,还没有很多经验。现将在某地穿江输油管线工程中,对直径为273、325、529、720mm的20号碳钢管采用的下向焊工艺介绍如下。 1.焊前准备 (1)对管接头的要求管接头的坡口型式及尺寸如图1所示。在对接头的坡口型式加工后,还须对距管端50mm以内的内、外壁进行打磨及清理,使内壁无锈蚀,外壁露出金属光泽。
In recent years, down welding has been in practice by the vast majority of welders to master, and accumulated a certain amount of welding experience. However, in the pipeline construction project, due to the short time of application, there is not much experience yet. Will now be a river in the pipeline project, the diameter of 273,325,529,720 mm on the 20th carbon steel pipe using down welding technology introduced below. 1. Preparation before welding (1) Requirements for pipe joints The groove type and size of pipe joints are shown in Fig.1. After the groove type of the joint is machined, the inner wall and the outer wall within 50 mm from the pipe end must be polished and cleaned so as to prevent the inner wall from rusting and the outer wall to have a metallic luster.