The difference between single-sided and double-sided welding of SSAW steel pipe

The production process of SSAW (Spiral Submerged Arc Welding) steel pipes affects the quality of single-side welding and double-side welding primarily through factors such as welding current, welding speed, number of welding layers, electrode type, and electrode diameter.

1. Welding Current

The proper selection of welding current directly impacts the final welding quality. Key points include:

High Welding Current: Increases productivity and penetration depth but can lead to defects like undercutting and porosity, especially in vertical welding where controlling the molten pool is challenging.

Low Welding Current: Reduces penetration depth and may cause defects such as incomplete penetration, poor fusion, slag inclusion, and disconnection. For beginners, managing the correct current is critical, as improper current settings can lead to severe weld defects.

2. Welding Speed

Welding speed is a primary parameter indicating welding production efficiency. The effects of welding speed include:

Fast Welding Speed: Leads to insufficient bath temperature, resulting in defects like incomplete penetration, poor fusion, and poor weld formation.

Slow Welding Speed: Causes prolonged high temperatures, increasing the width of the heat-affected zone, coarsening the weld grain, reducing mechanical properties, increasing weldment deformation, and causing slag inclusion due to backflow.

3. Welding Layers

The number of welding layers in single-side welding and double-sided forming also affects weld quality:

Thick Welding Layers: Detrimental to weld metal plasticity, and can cause slag backflow, resulting in defects like slag inclusion and poor fusion.

Thin Welding Layers: May lead to poor fusion on both sides of the weld if excessively thin.

4. Electrode Shape and Diameter

The properties of the weld metal are significantly determined by the electrode and its melting characteristics:

Electrode Shape and Diameter: Critical for weld quality. A large electrode diameter in the base layer can make the weld pool difficult to control, increasing the likelihood of defects.

Electrode Type: Must match the base metal properties to ensure proper weld quality. An inappropriate choice can lead to poor weld integrity, especially if the diameter is too large.

Summary

Understanding and controlling these factors is essential for high-quality welding of SSAW steel pipes. Proper management of welding current, speed, layers, and electrode properties ensures optimal weld quality and production efficiency, reducing defects and enhancing the overall durability of the welds.