When processing spiral tube forming, pre-bending and sizing are the very major steps.

Since the size of the rebound of tube blank affects the intrinsic quality of steel tube, here we adopt pre-bending as a cure to such problem. On the other hand, in pursuit of accuracy as it is an important parameter in determining quality of steel tube, sizing is inevitable in the whole process.

The aforementioned steps would eventually contribute to obtaining ideal steel pipe blank.

 

Now let us dive into the formation process and characteristics of submerged arc welding of galvanized spiral steel pipes with 630*3 ribs.

The principle process of submerged arc welding

Submerged arc welding is the utilization of thermal energy. Note the differences with manual welding rod arc welding—in submerged arc welding the welding wire is exposed; there is no coating.

Submerged arc welding is in practice pre-paved welding flux to be welded. The submerged arc welding wire first extends into the flux, then the arc is formed under the flux. The formation process of the submerged arc welding is as such described so that the welding wire is correctly contacting the target workpiece.

After the start button is pressed, the welding wire and the workpiece are immediately energized, and the welding wire is returned. Withdrawing, the arc ignites; the welding carriage advances; the welding wire continuously conveyed downwards; the arc maintained to burn under the flux layer, and the welding pool formed below the arc.

Around the arc, the flux melts and forms a cavity. The cavity and the pool then continue to advance, and the metal behind the pool solidifies to form a continuous weld. Since this process is performed under the flux, we are not able to see it with the bare eyes—it can be seen with X-ray photography.

The spiral steel pipe adopts the technology of automated submerged arc welding, offering significantly higher production efficiency, reduced production auxiliary time, and the time for changing the welding rod is saved. In addition, the welding conditions are clean and have no spatter, saving cleaning time. In the end, we also gain superior quality of the welding seam.

Machine-controlled automated welding technology also provides the necessity for the delivery of the spiral welded pipe plant, so that the production time of the large spiral steel pipe is guaranteed, hence this production system is still widely used.

Into more details

  1. The pressure-bearing fluid is mainly used for X46 welded pipe as the tube blank, which is often spirally formed in certain temperature. It is used for welding with double-sided submerged arc and is mainly used for spiral seam welded steel pipe devices as well as the transportation of pressure fluid. The endurance of the steel pipe to withstand pressure is solid and the welding performance is also beyond normality. After a variety of complicated scientific inspections and experimentations, its usage situation is relatively safe and reliable. The solid diameter of the steel pipe is large, the transmission efficiency is high, and it can effectively and vastly save the cost of laying pipelines. It is mainly used for pipelines for transportation of oil and natural gas.
  2. General low-pressure fluid transport is mainly for hot-rolled steel coiled tube blanks, often for specified temperature spiral molding. High-frequency lap welding method is typically used for general low-pressure fluid conveying spiral seam high-frequency welded steel pipe, welding steel with spiral welds.
  3. The hot rolled steel strip is used as the tube blank, often formed by spiral molding, and made of double-sided submerged arc welding or high-frequency welded steel pipe. It is typically used for the foundation pile steel pipe for civil building structures, wharves, and bridges.
  4. The general low-pressure fluid transport is for hot rolled steel strip coiled tube. Regular temperature spiral molding for submerged arc welded steel pipe typically use double-sided automatic submerged arc welding, or single-sided welding method for water, gas, air and steam and other general low-pressure fluid transport.
  5. The pressure fluid transport is based on the hot-rolled steel strip for tube blanks, regular temperature spiral molding, and high-frequency lap welding method used for pressure fluid transmission spiral seam high-frequency welding steel pipe device. The steel tube has strong pressure endurance capacity and fine plasticity, which facilitates well in welding and processing. It is typically used for the laying of pipelines connecting petroleum, natural gas, etc.