Do you know the sub arc welding process (SAW) and what it’s used for?
Find out more about this unique process and it’s applications. As well as equipment, advantages and disadvantages.
What is submerged arc welding?
Submerged arc welding is an arc welding process. Using an electrical current through wire to the workpiece, forming an arc. This creates the weld, joining two metal workpieces together. However, unlike other arc welding processes such as MIG, the arc is “submerged” under a layer of flux.
Submerged arc welding applications.
- Common in the welding of industrial cans and vessels, the saw welding process produces a strong, clean weld.
- Materials include carbon steels (low and medium), high-strength, low-alloy steels and nickel based alloys.
- It’s an ideal process for heavy plate welding. As well as surfacing applications like weld overlay and hard facing of structural/vulnerable metals.
What is a sub arc welder?
The process of submerged arc welding needs special equipment compared to other welding processes. A sub-arc welder needs to have a high duty cycle and output amperage to handle demand. Power sources are often in the region of 800 – 1200 amps!
You will also need a welding head/torch holder to move along the workpiece and lay down the weld. Automatic submerged arc welding usually consists of a column and boom manipulator. As well as a welding tractor/carriage. Manual SAW welding uses a power source and hand-held torch.
Finally, a flux hopper to distribute the flux over the weld bead is integral to SAW welding.
What is the function of flux in submerged arc welding?
Flux is used in submerged arc welding to provide a protective layer over the weld pool. Thus helping to prevent contamination, improving strength and integrity, and shaping the bead.
It also helps in concentration of heat into the weld pool, enabling better penetration. As well as assisting with arc striking and stability.
Why is submerged arc welding referred to as submerged?
Submerged arc welding is known as submerged due to the use of flux “submerging” the arc and weld zone. It’s applied using a flux hopper over the weld pool as the welding head moves across the workpiece.
Advantages of submerged arc welding.
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Extremely high deposition rates for greater productivity
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Little to no fume, spatter or arc light, improving working conditions
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Simple operation, low skill requirement.
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Better quality, consistent welds with deep penetration
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An easy to automate process, suitable for both indoor and outdoor applications.
Disadvantages of submerged arc welding.
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Often limited to flat or horizontal welding positions
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Best used on thicker steel/stainless steel and a few nickel-based alloys
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Not renowned for it’s portability
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Most suited to large rotating pipes and vessels, as well as long, straight weld seams
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Involves more post-process handling and cleaning, like slag removal and flux recovery. Although flux recovery can be automatic with extra equipment.
For a real-life case study into the SAW process and how it benefits one of our clients, click here.
For more information on submerged arc welding systems for sale, click here to view our latest stock. Alternatively, we are always looking to buy submerged arc welding machines. Send Peter and Bev details for a valuation!
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Reporter – Tom Pegden PICTURE WILL JOHNSTON
