Submerged arc welding is a welding process that produces incredibly clean, spatter-free welds without all the flash and chaos.

It’s been around for over 70 years, so you know it’s the real deal. But is it right for you, your fab shop, and any new automation efforts you may want to bring to the table? Or is it just an old-school technique with no future potential? 

Don’t worry, we’ve got your back! By the end of this article, you’ll be talking submerged arc welding with the best of ‘em. 

We’ll go over: 

• What is submerged arc welding? 
• How does it work? 
• What is it good for? 
• A short history of this type of arc welding
• Can submerged arc welding be automated?

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Let’s get started! 

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What is submerged arc welding (SAW)?

Submerged arc welding, also known as SAW, is an arc welding process where the arc is shielded by a blanket of granular flux. The flux is continuously fed into the weld zone, covering the molten metal.

Submerged arc welding is versatile and can join mild steel, low alloy, and stainless steels, producing welds that are uniform, dense, and strong. 

It is commonly used to weld boiler shells, pressure vessels, shipbuilding components, heavy construction equipment, and pipelines. 

When you need high-quality, high-deposition rate welds for heavy-duty applications, submerged arc welding is definitely one of the most reliable, time-tested solutions. 

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How does submerged arc welding work?

To work its magic, submerged arc welding uses an arc between a continuously fed bare metal electrode and the workpiece to melt the metals at the joint.

No shielding gas is necessary

Unlike gas welding, submerged arc welding does not require a shielding gas to protect the weld pool from contamination because the arc and weld pool are submerged under a blanket of granular flux. 

The flux generates shielding gasses to protect the weld pool.

No limits to welding depth 

Another advantage is that submerged arc welding can produce welds of unlimited depth in a single pass. The weld pool is submerged under the flux blanket, so atmospheric conditions have no effect on it. 

Versatile? Yes. Productive? Absolutely.

Submerged arc welding is a versatile and productive process that’s perfect for both manual and mechanized welding. 

You can use it to weld most commercial metals and alloys, especially mild steel and low alloy steels. Plus, the high deposition rates possible with submerged arc welding make it extremely well-suited for welding thick sections.

Submerged arc welding has been around for a very long time and continues to be popular in many industries, such as shipbuilding, structural steel fabrication, and pressure vessel manufacturing, due to its versatility, quality, and speed. 

Most recently, the introduction of flux-cored wires and tubular electrodes has expanded its applications to include the welding of stainless steels and non-ferrous alloys.

Where is submerged arc welding used?

Submerged arc welding is used in many heavy industries where thick materials need to be joined together. 

Some of the most common applications are:

• In shipbuilding, it's pivotal for welding thick steel plates that form ship hulls and various parts, perfectly suited for the 1-inch or thicker plates typical in this field. SAW's capability to weld at challenging angles is a huge benefit to hull construction.
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• For pressure vessels, like storage tanks and boilers, SAW is a go-to due to its compatibility with thick steel plates and its high-quality weld output, perfect for handling high pressure.
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• Within structural steel applications, such as steel buildings and bridges, SAW is a mainstay for its ability to manage thick steel sections efficiently, offering high deposition rates that boost productivity.
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• Wind tower fabrication, where its ability to produce long, high-quality welds is absolutely crucial for assembling large, thick steel sections of wind turbines, which ensure durability against environmental stress.
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• Heavy machinery manufacturing, including the production of cranes, mining equipment, and heavy-duty vehicles, where SAW's deep penetration and strong welds are 100% critical for the machinery's structural integrity and performance.
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• Pipe manufacturing for oil and gas industries, where SAW sees a lot of work for its efficiency in welding long stretches of thick-walled pipes, guaranteeing the safety and reliability required for transporting these all-important resources.
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• In railroad construction, SAW is a tremendous asset in manufacturing railroad tracks and repair works, providing strong, reliable welds that can withstand the high stresses and loads from train traffic.
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• Construction of large industrial fans and turbines, for assembling the heavy and thick components of industrial fans and turbines. SAW helps get deep penetration welds that offer the necessary strength and longevity.
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• Manufacturing of earthmoving and construction equipment, in producing the robust frames and structures of bulldozers, excavators, and other construction machinery, SAW's capability to join thick materials is invaluable.

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A short history of submerged arc welding

Submerged arc welding has been around for nearly a century. 

Let’s recap its long and varied history: 

• It was first developed in the 1930s and grew in popularity during World War II for shipbuilding. The earliest applications were for welding mild steel, using lime (calcium carbonate) as a flux. Lime provided good arc stability but limited weld quality.
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• In the 1950s, fused fluxes were first introduced, giving submerged arc welding the capability to weld a wider range of materials, including high-strength steels. Automated and mechanized welding began in the 1960s, which increased welding speeds and quality.
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• By the 1970s, submerged arc welding dominated heavy steel fabrication; it allowed for high deposition rates, good weld quality, and minimal operator involvement. The introduction of solid wire and cored wire in the 1980s provided even higher welding speeds and superior weld properties.
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• In recent decades, submerged arc welding has expanded to more alloys and applications. Now, it’s a dominant process for manufacturing pressure vessels, pipelines, offshore structures, mining equipment, and more. New developments focus on portability, automation, and robotics.

All in all, submerged arc welding has come a long way in its nearly 100-year history. While it was originally developed for shipbuilding, it now has a wide range of uses in many heavy industries.

Now, improvements in welding wires, fluxes, power sources, and automation have allowed for its increased capability, speed, efficiency, and quality. 

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Can submerged arc welding be automated?

Submerged arc welding is highly suitable for automation and mechanization.

In fact, a large portion of submerged arc welding is done using automated welding equipment. 

The process lends itself well to automation for several reasons:

• Since no shielding gas is required, the equipment does not need to handle shielding gasses. This simplifies the design and reduces costs — the flux itself shields the arc and molten weld pool from the atmosphere.
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• Submerged arc welding can achieve very high deposition rates, up to 18 kg of weld metal per hour. Automated SAW equipment can take full advantage of these high deposition rates to weld at high speeds. The result? High productivity and lower costs.
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• The welding heads used in submerged arc welding are simple and can easily be manipulated by automated welding equipment. The flux and wire are fed through the welding head, which requires only basic motion control.
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• Submerged arc welding does not need tight joint preparation or fit-up. This makes it easier for automated welding equipment to access the joint and deposit weld metal. Minimal joint preparation also reduces costs, which is also a big plus. 
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• Much of submerged arc welding involves repetitive welding over long joints or large areas. This repetitive nature is where automated welding equipment truly shines because it can consistently and efficiently deposit many meters or even kilometers of weld metal.

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Summing up

Submerged arc welding might not be the most glamorous or widely known welding technique, but it's an invaluable process in many heavy industries. 

With its high deposition rates, deep penetration, and automated capabilities, SAW helps manufacture everything from ships to pipelines to construction equipment. 

Plus, if your business is centered around large-scale, heavy-duty industrial processes, automating submerged arc welding may be a reality well worth looking into. 

We anticipate that it can cost a pretty penny, but the excellent ROI of automation can mean your sizable investment will end up paying for itself! 

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Next steps 

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