SubArc Welding Machines

Submerged Arc Welding (SAW), often referred to as sub arc welding, is a welding process that is commonly used in various industries for welding thick steel plates and for large-diameter pipes. The process uses a granular flux to create a protective atmosphere over the welding arc.

In submerged arc welding, an electric arc is created between a continuously fed bare electrode and the workpiece. The arc generates intense heat, melting both the electrode and the workpiece, creating a weld pool. Simultaneously, a layer of granular flux is continuously fed onto the welding area. This flux melts and forms a protective slag over the weld pool, preventing atmospheric contamination and facilitating a cleaner weld.

Find a great video from weld.com here that goes back to school to explain the technique.

The process is called "submerged" because the arc and the molten weld pool are shielded, or "submerged" by a layer of granular flux.

Advantages:

• High deposition rates - submerged arc welders can achieve high weld metal deposition rates, making it suitable for welding thick sections. 
• High efficiency - the process is highly efficient for long, continuous welds in flat or horizontal positions. 
• Good weld quality - SAW typically produces sound and high-quality welds with good mechanical properties. 

Disadvantages:

• Limited joint access - the process is mainly for flat and horizontal welding. 
• Limited portability - most set ups involve structural components like column and booms, as well as beam lines, making portability difficult.
• Initial set up costs - due to the amount of equipment required, initial investment costs for SAW can be high compared to manual welding.

Submerged arc welders are generally used for heavy fabrication welding applications involving thick plate and large diameters. This is due to the strength of the weld produced, fast deposition rates, and the ability to use multiple welding heads, creating simultaneous weld passes at the same time.

Submerged arc welding is widely used in various applications. These include welding of pressure vessels and boilers, fabrication of structural steel components, and shipbuilding. As well as Welding of pipes and pipelines, rail fabrication, and welding of heavy equipment components.

See more information in our submerged arc welding guide.

Most submerged arc welders involve some welding automation, and can be confirgured for automatic or semi-automatic welding. The process lends itself to automation due to the equipment required and characteristics of the process.

Common troubleshooting tips for sub arc welding include:

• Insufficient penetration - can be caused by low current or voltage settings, excessive travel speed, and inadequate joint preparation.
• Excessive penetration - can occur when current or voltage settings are too high, travel speed is too slow, or excessive joint preparation.
• Weld bead irregularities - occurs when there is uneven flux distribution, incorrect wire feed or voltage settings, or poor wire alignment.
• Porosity in the weld bead - can be caused by contaminated flux, moisture in the flux, or insufficient preheating.
• Arc instabilities or arc blow - can occur when there is magnetic interference, incorrect electrode polarity, or insufficient or excessive flux coverage.

Always refer to the equipment manuals and welding specification to ensure all settings and parameters are correct.

To help you achieve success in your submerged arc welding process, take a look at these tips!

• Joint preparation - ensure proper joint preparation, including bevel angle, root gap, and cleanliness. Good joint fit-up is crucial for achieving high-quality welds.
• Proper voltage and current settings: set the welding parameters, including voltage and current, according to the material thickness and joint configuration. Refer to welding procedure specifications (WPS) and adjust parameters as needed.
• Flux handling: store flux in a dry environment to prevent moisture absorption, which can lead to porosity and other welding defects. Use a flux recovery system to collect and recycle unused flux, reducing material waste.
• Wire alignment: ensure the welding wire is properly aligned and centered in the joint. Misalignment can lead to irregular weld beads and poor penetration.
• Preheat for thick materials: preheat the workpiece, especially for thicker materials, to reduce the risk of hydrogen-induced cracking and improve weldability.