Submerged Arc Welding (SAW) is a versatile and widely used arc welding process known for its high deposition rate, deep penetration, and ability to produce high-quality welds. The process is characterized by the use of a continuous consumable electrode and a granular flux that completely covers the welding arc.
If you are reading this article, chances are that you are wondering whether submerged arc welding is the ideal welding process for your production needs. In this article we are going to cover all about submerged arc welding. Let’s start by identifying the basic components of a submerged arc welding process system.
Basic Components of a Submerged Arc System
To join metal pieces by means of submerged arc welding (SAW), the following basic components are needed.
Power Source: Provides the electrical energy to create and maintain the arc. It can be a constant voltage or constant current type, depending on the application.
Wire Feeder: Delivers the electrode wire at a controlled speed to the welding arc.
Welding Torch: Holds the electrode wire and directs it towards the welding joint. It may also include a nozzle for shielding gas if needed.
Flux Hopper and Delivery System: Stores the granular flux and delivers it to the weld joint to cover the arc and welding pool.
Control System: Regulates the welding parameters like voltage, current, wire feed speed, and travel speed. It can be manual or automated.
Welding Head (Optional): Used in automated SAW systems to move the welding gun or torch along the welding joint.
Electrode Wire: A continuous consumable wire made of a material compatible with the base metal. It melts in the arc and adds filler metal to the joint.
Granular Flux: A mixture of minerals that provides shielding, slag formation, electrical conductivity, and sometimes alloying elements to the weld.
Shielding Gas (Optional): Some SAW systems may use additional shielding gas (like CO2) along with the flux to improve weld quality.
These are the essential components of a submerged arc welding (SAW) system. The specific design and configuration may vary depending on the application and level of automation.
Knowing the basic components, let’s now dig deeper into how submerged arc welding (SAW) works.
How Submerged Arc Welding Works
- Flux Delivery: Granular flux is fed from a hopper and deposited onto the joint to be welded. The flux serves multiple purposes in the SAW process
- Arc Initiation: An electric arc is struck between the continuously fed electrode and the workpiece. This arc is completely submerged beneath the layer of granular flux, shielding it from the atmosphere
- Flux Melting and Shielding: The intense heat of the arc melts the flux, creating a molten slag that covers the weld pool. This molten flux serves several crucial functions:
- Shielding Gas: It decomposes to produce shielding gases that protect the welding pool from atmospheric contamination, resulting in cleaner and stronger welds
- Slag Formation: The molten flux solidifies on top of the weld, forming a slag layer that protects the cooling weld metal and improves its properties
- Electrical Conductivity: The molten flux provides a conductive path for the electric arc, maintaining a stable arc, and allowing the electrode to melt and fuse with the base metal. This ensures a continuous welding
- Alloying Addition: In some cases, the flux may also contain alloying elements that are transferred to the weld metal, improving its properties
- Electrode Melting and Deposition: The electrode is continuously fed into the welding pool, melting due to the heat of the arc. The molten electrode metal mixes with the molten base metal, forming the weld.
- Slag Removal: After the weld has cooled, the solidified slag layer is removed by chipping or grinding.
Advantages of Submerged Arc Welding
Submerged arc welding (SAW) offers numerous advantages that make it a preferred choice for many welding applications. Let’s bring to the table 10 clear advantages of this welding process.
High Deposition Rate: SAW enables high welding speeds and deposition rates due to the continuous feeding of electrode wire and the shielding effect of the flux, making it ideal for large-scale and high-volume production.
Deep Penetration: The concentrated arc and the protective flux layer allow for deep penetration into the base metal, making it suitable for welding thick materials with a single pass.
High-Quality Welds: The flux shielding protects the weld pool from atmospheric contamination, resulting in clean, consistent, and high-quality welds with minimal defects.
Versatility: SAW can be used to weld a wide range of materials, including carbon steel, stainless steel, and various alloys, making it adaptable to different projects and industries.
Minimal Operator Skill Requirement: Once the parameters are set, SAW requires relatively less operator skill compared to other welding processes like TIG or MIG, reducing the dependency on highly skilled welders.
Automation Potential: SAW is well-suited for automation and mechanization, which increases productivity, improves consistency, and reduces labor costs.
Low Hydrogen Levels: The flux used in SAW helps to minimize hydrogen absorption in the weld, reducing the risk of cracking and improving the mechanical properties of the weld.
Reduced Distortion: The deep penetration and the slow cooling rate associated with SAW result in less distortion in the welded components compared to other processes.
Minimal Fumes and Radiation: The submerged arc and the flux layer help to reduce the number of fumes and radiation emitted during welding, creating a safer working environment for the operator.
Economic Efficiency: SAW is a cost-effective welding process due to its high deposition rate, low filler metal consumption, and efficient use of flux.
These advantages make submerged arc welding a popular choice for many applications where high-quality welds, productivity, and cost-effectiveness are essential. But, before considering that, let’s look at the disadvantages or limitations of submerged arc welding.
Limitations of Submerged Arc Welding
Despite the many benefits that submerged arc welding (SAW) offers, it also has certain disadvantages and limitations that should be considered before choosing it for a project. Let’s consider now 10 disadvantages of this welding process.
Positional Limitations: SAW is primarily limited to flat and horizontal welding positions due to the fluidity of the molten flux and slag. Welding in vertical or overhead positions is generally not possible with standard SAW equipment.
Limited Visibility: The welding arc is submerged under the flux layer, making it difficult for the operator to directly monitor the welding pool and adjust as needed. This can lead to potential defects if not properly controlled.
Slag Removal: The slag layer formed on top of the weld needs to be removed after welding, which can be a time-consuming and labor-intensive process.
High Heat Input: SAW often involves high heat input, which can lead to issues like distortion, especially in thin or heat-sensitive materials.
Equipment Complexity: SAW systems can be complex and expensive, especially for automated setups, requiring specialized equipment and trained operators.
Flux Handling: The handling and disposal of flux can be messy and requires proper precautions to avoid environmental and health hazards.
Limited to Ferrous Metals: SAW is generally most suitable for welding ferrous metals like carbon steel, stainless steel, and some nickel-based alloys. It may not be the best choice for other materials like aluminum or titanium.
Not Ideal for Short Welds: The setup time for SAW can be relatively long, making it less efficient for short welds or frequent starts and stops.
Porosity Risk: If the flux is not properly maintained or if there is moisture contamination, there is a risk of porosity in the weld.
Limited Joint Access: The bulkiness of the welding head and the need for flux delivery can make it difficult to access tight or confined spaces.
Despite these limitations, submerged arc welding (SAW) remains a valuable welding process for many applications due to its numerous advantages in terms of quality, productivity, and cost-effectiveness.
Understanding its advantages and limitations allows for better planning and informed decision-making when selecting the most appropriate welding method for a specific project. So, what applications are most suitable for submerged arc welding? Let’s now answer that question.
Applications of Submerged Arc Welding
Most commonly, submerged arc welding (SAW) is widely used for heavy fabrication. Now, under this umbrella many segments can be included. Let’s talk about a few of them.
Shipbuilding: SAW is extensively used in shipbuilding for joining large steel plates and sections due to its high productivity and ability to handle thick materials.
Offshore Construction: SAW is employed in the construction of offshore platforms, pipelines, and other structures due to its deep penetration and ability to withstand harsh marine environments.
Pressure Vessel Fabrication: SAW is used to weld thick-walled pressure vessels for various industries, including oil and gas, chemical processing, and power generation.
Pipeline Construction: SAW is the preferred method for welding long pipelines due to its high deposition rate and ability to create strong, reliable joints.
Structural Steel Fabrication: SAW is used to join beams, columns, and other structural components in bridges, buildings, and other large structures.
Heavy Equipment Manufacturing: SAW is used to weld components of heavy machinery, such as mining equipment, construction equipment, and agricultural equipment.
Railcar Manufacturing: SAW is used to join various components of railcars, including underframes, sidewalls, and roofs.
Wind Tower Manufacturing: SAW is used to weld large sections of wind turbine towers.
Storage Tank Fabrication: SAW is used to construct large storage tanks for various liquids and gases.
Submerged arc welding can also be used for surfacing applications, such as hardfacing and cladding, to improve wear resistance and corrosion resistance of components.
In summary, SAW is a versatile welding process with numerous applications across various industries, primarily in heavy fabrication, where its ability to handle thick materials, high deposition rates, and deep penetration make it a valuable asset.
To excel in the submerged arc welding process, you need top-notch equipment. Let’s take a look at some features of the most reliable submerged arc welding equipment available.
The Equipment for Submerged Arc Welding
Submerged arc welding (SAW) uses specialized equipment to achieve its unique welding process. We have successfully used the following Miller SAW power sources. Over the years, our customers have confirmed the reliability of these machines.
Miller SubArc DC 1000 Digital
The Miller SubArc DC 1000 Digital welder includes interface controls, fixtures, digital control, and communication designed to improve welding performance and simplify equipment integration into more advanced applications.
Miller SubArc AC/DC 1000 Digital
The Miller SubArc AC/DC 1000 Digital welder is part of a series of digital submerged arc power supplies. They include digital interface controls and accessories. The Miller SubArc AC/DC 1000 communicates digitally to improve welding performance and simplify equipment integration into more advanced applications.
Miller SubArc 3 Wheel Tractor
The Miller SubArc 3-wheel tractor has a compact size that makes it easy to set up. This allows for greater flexibility and additional submerged arc configuration options for shipbuilding, railcar construction, and general manufacturing.
In a few words
In general, submerged arc welding (SAW) is a powerful and efficient welding process that plays a crucial role in many industrial applications. Its ability to produce high-quality welds at high speed and with deep penetration makes it a valuable tool for manufacturers around the world.
We have been helping companies in different countries to set up welding operations, including the submerged arc welding process, for several decades. Please do not hesitate to contact us as soon as possible for assistance.
