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　　When welding one layer of multi-layer welding seam, the liquid zinc can be greatly reduced by melting the zinc layer and vaporizing and evaporating galvanized steel pipes out of the weld. When fillet weld is welded, the Hot DIN2448 st52 Seamless Carbon Galvanized Steel Pipe is melted in the first layer and vaporized and evaporated to escape from the weld. The method is to move the end of the electrode forward about 5-7 mm, and then to continue to weld when the zinc layer is melted back to its original position. If short slag electrode such as J427 is used in cross welding and vertical welding, the undercut tendency will be very small; if the front and back transport rod technology is used, the defect-free welding quality can be obtained.

　　The preparation before welding of square pipe controlled by welding process is the same as that of common low carbon steel. Galvanized steel pipes should be noted that the groove size and the galvanized layer near the groove should be carefully handled. In order to penetrate, the groove size should be appropriate, generally 60-65 degrees, leaving a certain gap, generally 1.5-2.5 mm. In order to reduce the penetration of zinc into the weld, before welding, the galvanized steel pipes in the groove can be removed and then welded. In the actual supervision work, the centralized grooving, no blunt edge technology and two-layer welding technology are adopted to control the centralized grooving, which reduces the possibility of non-penetration.

　　Welding rod should be selected according to the base material of galvanized steel pipes. J422 is a common choice for low carbon steel due to its easy operation.

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