Electrode arc welding of pipelines: Electrode arc welding of pipelines is currently the most commonly used welding method in general factories. It is a method of melting the pipe wall and electrode by manual operation, mixing to form a molten pool and solidifying to form a weld. Electrode arc welding equipment is simple, flexible and easy to apply, and is suitable for welding small diameter pipes, thin wall pipes and narrow pipes. Electrode arc welding can be applied to any space and position; rotary welding of pipes: when processing pipes in prefabricated plants, rotary welding is generally used, which is easy to operate and has high productivity. The quality of pipeline welding is closely related to butt welding and spot welding; pipeline butt welding and tack welding: the specification of pipeline butt welding should comply with the relevant standards of national enterprises. At the same time, the flatness of the bevel end face should be less than 0.5 mm, and the dislocation of the joint assembly should not be greater than 1 mm. For small-diameter pipes, it is only necessary to position welding on the symmetrical sides of the pipe. For large-diameter pipes, three or more welds can be spot welded, and the size of the spot welds should be determined. When the thickness of the pipe wall is less than or equal to 5 mm, then the thickness of the welding point is 2.5-3 mm, if the thickness of the pipe wall is greater than 5 mm, the thickness of the welding point is about 4 to 5 mm, and the length of the spot welding is about 20-30 mm mm, in order to facilitate the penetration of the joint, both ends of the solder joint must be made into a gentle slope shape
