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Welding Of Galvanized Steel Pipeline

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The galvanized steel pipeline is characterized by its outstanding benefits such as rust resistance, long life, reduced preliminary expense and also upkeep expenses, has been wieldy used in exterior and also indoor, aquatic and below ground applications

Galvanized steel pipe is a 20um thick zinc finishing outside of the reduced carbon steel pipeline. The melting factor of zinc goes to 419 ° C and the boiling factor is around 908 ° ℃. In welding, zinc is melted externally of the molten pool or at the root of the weld. Given that zinc has a fairly high strong solubility in iron, the zinc fluid will deeply deteriorate the weld steel along the grain boundary, developing "fluid steel embrittlement". At the exact same time, zinc and iron can form an intermetallic weak compound, which decreases the plasticity of the weld steel and leads to splits under the action of tensile tension.

When welding galvanized steel, the surface area of groove and the side of the zinc layer under the action of arc warm, oxidation, melting as well as dissipation of white smoke and heavy steam quickly result in weld porosity. ZnO developed by oxidation has a high melting factor, above 1800 ° C. If the parameters are also little in the welding process, ZnO slag inclusion will certainly be created. On the other hand, as Zn ends up being a deoxidizer, FeO-MnO or Feo-Mno-Sio2 oxide slag addition with low melting factor will certainly be created. It has to be kept in mind that the white dust of zinc volatilization is dangerous to body and the galvanized layer at welding should be polished off.

Step 1: Polishing

The galvanized layer needs to be gotten rid of at the welding component, otherwise will certainly take place bubbles, trachoma, incorrect welding and other defects, which causes fragile welding seam and also rigidness reductions.

Action 2: Weld groove

The prep work of galvanized steel before welding resembles the general low carbon steel, it is necessary to take note of the groove dimension and also galvanized Discover more here layer. The groove size is normally 60 ~ 65 ° and there is a specific space, generally 1.5 ~ 2.5 mm; In order to decrease the penetration of zinc into the weld, the galvanized layer in the groove can be removed before welding and after that bonded. In functional welding, the groove is normally focused as well as no blunt side is left. Two-layer welding lowers the possibility of incomplete welding. The welding pole should be picked according to the base material of galvanized steel tube. Usually talking, J422 is an optimal choice.

GL weld groove

Action 3: Welding

In the first layer of multilayer welding weld, attempt to melt the zinc layer as well as make it vaporized, evaporation, this can substantially minimize the zinc fluid remained in the weld. The exact same technique is used for fillet welds. First move the electrode tail forward concerning 5 ~ 7mm, and after that return to the original placement to continue welding after melting the zinc layer. If the choice of brief slag electrode such as J427, there will certainly be an extremely small bite edge propensity; Back and forth input electrode can obtain the welding quality without defects

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on Jan 25, 21