Submerged arc welding is a standard industrial process wherein an arc is formed between a workpiece and an electrode. It was invented in by the E. O. Paton Electric Welding Institute in Kyiv, Ukraine as a driving force behind the Second World War. One of the most notable applications of this invention is the T34 military tank.
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While this welding technology has been around for almost a century, it is still an essential choice for many industries.
Submerged arc welding (SAW) is a welding method where similarly to other arc welding processes, the base metals are joined by forming an electric arc between the workpiece and an electrode.
SAW process’s defining element is how it protects the weld metal from atmospheric contamination. Submerged arc welding uses a powdered flux layer, generating shielding and slag while creating a smooth and clean weld. Other methods use shielding gas (MIG/TIG welding), flux-cored wire (FCAW), flux-coated electrode (SMAW), or controlled environment (plasma welding) for protecting the weld.
Submerged arc welding creates consistent welds by using a blanket of granulated flux. For this reason, the process can be operated only on positions that are flat and horizontal, with the weld advancing by either moving the welding system or the workpiece.
Flux is fed into the joint manually or by using a flux hopper. A single electrode or multiple wire electrode system is placed into the working area, surrounded by the flux blanket. Parameters such as the welding current, arc voltage, and wire feed speed are set depending on the type of metal, its thickness, and desired mechanical properties. Electric current is supplied to the electrodes, producing intense heat that melts and fuses the base material and the filler wire to the bead.
The molten metal cools down, creating strong uniform welds and reusable granular flux at the surface and slag underneath. A hopper collects the reusable flux, while slag is usually peeled off manually.
SAW produces high-quality welds with fewer weld defects than other processes. However, this does not mean that defects won’t ever occur. When they do, it’s generally related to wrongly set welding parameters.
Granular flux inside a hopper is usually composed of oxides from aluminium, calcium, magnesium, manganese, silicon, titanium, and zirconium. This composition suits the type of electrode to achieve the metal’s desired properties as it chemically reacts as it melts.
Bonded flux is produced by drying the composition and slowly baking it, usually with a compound such as sodium silicate. As an advantage, bonded flux can contain alloying elements, offering flexibility for some applications and protection against rust.
Fused flux is produced by melting the composition inside an electric furnace. The molten flux is formed into homogenous particles as it solidifies. It is excellent for creating consistent welds along the bead.
SAW uses a wire spool to feed the wire electrode into the weld. The wire’s thickness is usually between 1.6mm and 6mm. Electrodes may come in the form of solid, twisted, or cored wire and may be operated using different power sources.
Specific circumstances may need the use of modified wire electrodes and electrode systems to achieve the desired weld profile:
Twin-wire
Multiple wires
Single wire with hot/cold addition
Metal powder additive
Tubular wire
Multiple wire systems typically use a lead wire to improve penetration, while a trailing wire is used to add extra fill and improve the bead profile. Additional wires are used in the electrode system to add more deposition to the weld pool.
Submerged arc welding process is used with the following materials:
Copper alloys
Low to medium-carbon steels
Low-alloy steels
Mild steels
Nickel-based alloys
Quenched and tempered steel
Stainless steels
Uranium alloys
Submerged arc welding can operate on multiple power outputs, allowing it to manipulate the weld results. Multiple electrode systems enable SAW to run wires at different power sources, to better control the bead profile and penetration.
DCEP offers the most stability and penetration, while DCEN is optimal in increasing deposition rates. Running this welding process in AC is the middle ground where a balance between the two is achieved.
SAW is one of the preferred welding processes in fabricating pressure vessels, pipes, and boilers due to its strength in longitudinal and circumferential welding. This welding operation achieves a smooth weld pool from the continuously fed electrode.
The flexibility of SAW process allows it to be performed both indoors and outdoors which makes it suitable for shipbuilding. It’s perfect for creating long, straight welds for heavy metals which make up ship parts.
Metals used in the automotive and military industry are fit for SAW, along with the speed and efficiency it brings. This welding method is also perfect for automation, with the option to have multiple or single-pass welds based on the metal’s thickness.
The submerged arc process allows deep weld penetration, which is attractive to the railway industry.
The blanket of granular flux creates minimal welding fume and spatter.
Allows performing semiautomatic or fully automatic welding.
Flexible for both indoor and outdoor applications.
Creates smooth, uniform and deep welds.
Around 50-90% of the flux is reusable and recyclable.
In the world of industrial fabrication, achieving strong, consistent, and high-quality welds is essential for building durable structures and equipment. One welding method that has become a staple in heavy-duty applications is submerged arc welding (SAW). Known for its efficiency and ability to produce deep, high-quality welds, SAW is widely used in industries like shipbuilding, oil and gas, construction, and manufacturing. This blog post will explore the fundamentals of submerged arc welding, its benefits, and why it’s a preferred technique for large-scale fabrication projects.
Submerged arc welding (SAW) is a welding process that uses an electric arc to fuse materials together, typically metals, under a protective blanket of granular flux. This granular flux completely covers the welding arc and molten metal, shielding it from contaminants and reducing spatter and smoke. The process is fully automated or semi-automated, making it ideal for continuous welding on long seams and thick materials.
– Electrode: A consumable wire electrode that melts to form the weld, providing filler material for the joint.
– Flux: Granular material that covers the weld area, protecting it from atmospheric contamination and stabilizing the arc.
– Power Supply: Provides the current needed to create the electric arc, typically DC or AC.
– Welding Head: Feeds the electrode and flux into the weld zone, maintaining a consistent welding speed and quality.
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The submerged arc welding process is particularly well-suited for thick, flat, or horizontal welds. Unlike other methods, SAW doesn’t require a shielding gas, as the flux layer provides full protection. This allows for high deposition rates and deeper weld penetration, which are essential for projects requiring large, strong welds.
The SAW process is simple yet highly effective. Here’s a step-by-step look at how it works:
Submerged arc welding offers several unique advantages that make it a preferred technique for fabrication projects, especially in heavy industries. Here are some of the key benefits:
SAW is known for its high deposition rates, meaning it can deposit a large amount of weld material quickly. This allows for faster welding speeds, reducing project timelines and labor costs.
– Efficiency: The automated or semi-automated nature of SAW allows for continuous welding, which is much faster than manual welding methods.
– High Productivity: Faster welding speeds and high deposition rates make SAW ideal for projects with large volumes of welding, such as pressure vessels, pipelines, and structural components.
SAW produces deep weld penetration, resulting in strong, reliable welds that can withstand significant stress and pressure. This is particularly important in industries where structural integrity is essential, such as shipbuilding and oil and gas.
– Durability: The welds created by SAW are highly durable and have a low risk of cracking or defects.
– High Integrity: Deep penetration ensures that the welds are structurally sound, making SAW suitable for heavy-duty applications.
One of the standout benefits of SAW is its ability to produce clean, high-quality welds with minimal spatter. The flux layer not only protects the weld pool but also creates a smooth, consistent finish.
– Reduced Cleanup: SAW produces minimal spatter, which means less post-weld cleanup is needed.
– Smooth Finish: The protective slag layer results in a smooth, high-quality weld bead, reducing the need for grinding or polishing.
The flux used in SAW covers the welding arc, which reduces the amount of visible light, fumes, and spatter produced during the process. This makes SAW a safer option for welders and other personnel working nearby.
– Reduced Exposure to Fumes: The flux layer significantly reduces harmful emissions, creating a safer work environment.
– Lower Heat Radiation: Since the arc is submerged, there’s less intense light and heat exposure, enhancing safety for welders.
While SAW requires specialized equipment, it is highly cost-effective for large-scale projects due to its high speed, efficiency, and reduced labor costs. The ability to produce strong welds quickly means that fewer resources are needed to complete large volumes of welding.
– Lower Labor Costs: Automation reduces labor requirements and allows for faster project completion.
– Material Efficiency: High deposition rates and reduced spatter mean less material is wasted, adding to cost savings.
SAW is a versatile technique that’s ideal for heavy-duty industrial applications requiring large, continuous welds. Here are some common applications where SAW is frequently used:
In the oil and gas industry, pipelines need to be strong, reliable, and capable of withstanding high pressures and harsh environments. SAW is widely used for pipeline welding due to its high penetration and ability to produce long, continuous welds.
Examples:
– Welding large-diameter pipes for oil and gas transportation.
– Constructing high-pressure pipelines for water and wastewater systems.
SAW is often used in the fabrication of pressure vessels and storage tanks, where strong, defect-free welds are essential for handling high pressures and hazardous materials.
Examples:
– Fabricating storage tanks for chemicals, oil, and other industrial fluids.
– Welding pressure vessels used in industrial processing and power generation.
Structural components in buildings, bridges, and other infrastructure require durable, high-quality welds to ensure stability and safety. SAW is commonly used for welding beams, columns, and other structural elements in steel fabrication.
Examples:
– Welding structural steel for high-rise buildings and commercial complexes.
– Fabricating beams and girders for bridges and infrastructure projects.
The shipbuilding industry relies on SAW for its ability to create strong, corrosion-resistant welds. SAW is ideal for welding hulls, bulkheads, and decks, providing the strength needed to withstand the harsh marine environment.
Examples:
– Welding steel plates for ship hulls and offshore platforms.
– Constructing decks and other structural components for large vessels.
In the manufacturing of heavy equipment and industrial machinery, SAW is used to create durable welds that can handle heavy loads and repetitive use.
Examples:
– Welding frames and components for construction equipment.
– Fabricating machinery used in mining, agriculture, and manufacturing.
Submerged arc welding’s combination of speed, strength, and quality make it an indispensable technique for fabrication projects, especially those requiring heavy-duty, high-strength welds. The ability to produce clean, deep welds in a short amount of time is invaluable in industries where downtime is costly and safety is paramount. Additionally, the automation potential of SAW helps improve productivity, reduce labor costs, and minimize risks associated with on-site welding.
For any industry where reliability, durability, and cost-effectiveness are critical, SAW offers a solution that meets and often exceeds the demands of modern fabrication.
Final Thoughts
Submerged arc welding is a key technique in fabrication, offering unparalleled benefits in speed, quality, and durability. Whether used for pipelines, pressure vessels, structural components, or marine applications, SAW enables the creation of strong, high-integrity welds that withstand the most demanding industrial conditions. With its reduced spatter, minimal fumes, and ability to handle large-scale projects, SAW remains a preferred welding method for industries where precision, efficiency, and safety are essential.
For fabrication projects that demand long, continuous welds with high strength, choosing a fabrication provider skilled in submerged arc welding can ensure that each weld meets the highest standards, delivering reliable performance and long-term value.
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