Welding method of spiral steel pipe

Spiral pipe is a type of spiral seam welded pipe made from strip steel coil. The coil is formed into a pipe shape at room temperature and welded using an automatic double-wire double-sided submerged arc welding process.

Submerged Arc Automatic Welding Process

The submerged arc automatic welding process is similar to manual welding in that it uses slag for protection. However, in this process, the slag is not from the electrode coating but from specially smelted welding flux.

Key Characteristics of Spiral Pipe Welding:

- Extrusion Device Usage:

An extrusion device is used to press the inner surface of the steel plates on both sides of the unwelded seam. This eliminates uneven protrusions and ensures the surfaces are clean and smooth before welding.

The extrusion device also acts as a positioning device for the welding head. It ensures that the welding head is tightly fixed and moves accurately along the unwelded seam, keeping the welding head always centered on the seam.

This method ensures that the welds produced by the automatic welding process are stable and of high quality, with minimal need for manual repairs.

- Automation and Efficiency:

The process is automated, enhancing efficiency and consistency.

Welding under a submerged arc offers strong heat exchange and protection, resulting in high-quality welds.

The submerged arc protects the welding process as the arc is buried under the flux.

Differences from Manual Welding

Use of Welding Wires Instead of Rods:

- Continuous Wire Feeding: Submerged arc automatic welding uses welding wires, which can be continuously fed, unlike welding rods that need to be replaced once burned out.

- Operational Efficiency: Welding wires eliminate the need to stop and replace rods, enhancing operational efficiency.

- Formation of Cavity: The continuous feeding of the welding wire and the melting of the flux form a cavity where the arc burns stably, hence the term "submerged arc automatic welding".

In summary, the submerged arc automatic welding method for spiral pipes ensures automation, high protection performance, and stable, high-quality welds. This process uses continuous welding wires instead of rods, significantly improving efficiency and reducing the need for manual intervention.