How to improve the rectangular pipe welding method?

Rectangular pipes are used in various building structures and engineering structures, such as building steel for building beams, bridges, transmission towers, lifting and transportation machinery, ships, industrial furnaces, reaction towers, container racks, warehouse shelves, etc. - rectangular pipes play a very important role in the construction industry, and are a topic of concern for builders and building materials manufacturers from time to time. So how can we improve the welding of rectangular pipes after all?

1. The allowable tendency of the wall thickness of rectangular pipe shall not exceed plus or minus 10% of the nominal wall thickness when the wall thickness is not more than 10 mm, and plus or minus 8% of the wall thickness when the wall thickness is more than 10 mm, except for the wall thickness of corners and weld areas.

2. Generally, the delivery length of rectangular pipe is 4000mm-12000mm, most of which are 6000mm and 12000mm. The rectangular pipe is allowed to consign short and non fixed length products not less than 2000mm, and can also be delivered in the form of interface pipe, but the demander shall cut off the interface pipe when using it. The weight of short and non fixed length products shall not exceed 5% of the total delivery volume, and the theoretical weight of rectangular pipes greater than 20kg/m shall not exceed 10% of the total delivery volume.

3. The bending of rectangular pipe shall not exceed 2mm per meter, and the total bending shall not exceed 0.2% of the total length

For rectangular pipe welding, butt weld groove shall be processed according to process requirements, and gap shall be reserved for splicing. The design of welded joints is a relatively thin link in welding engineering. The groove mode plays an important role in controlling the internal quality of the weld and the manufacturing quality of the welding structure.

The process requirement is to weld a layer of weld thoroughly to ensure good formation of the reverse side. The welding current, arc voltage, wire feeding speed and welding speed can be adjusted according to the equipment model. In order to reduce the welding deformation of rectangular pipes, the welding consumption guideline is welded symmetrically from the middle to both sides in layers and segments. The welding deformation is smaller than that of straight through welding, which is conducive to stress dispersion and release, Prevent complex stress during welding.

During straight through swing welding, the narrow plastic deformation zone formed by welding only appears once, and because of continuous swing welding, the heat input is large, the heating area is large, and the plastic deformation zone formed by shrinkage is large, so the shrinkage deformation after welding is large.

In case of layered and segmented skip welding, the cross section of each layer is very small, so the heat required is small, and each layer is divided into several sections to stop the skip welding. Each section of welding is basically to re-establish a temperature field on the cold steel plate, and each time presents a narrow plastic deformation zone. Therefore, the uniform width of the plastic deformation zone is smaller than that of the corresponding layered straight through welding, and the longitudinal shrinkage is also small, The welding deformation is smaller than that of the straight through swing welding with one continuous filling.

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