Today I will be discussing the definition, applications, diagram, equipment, working, advantages, and disadvantages of submerged arc welding (SAW). Previously, an article was published on Flux-cored arc welding (FCAW). Check out!
Read more: Working principles of flux cored arc welding
What is submerged arc welding (SAW)?
Submerged arc welding is another type of arc welding process that uses a continuously fed consumable tubular electrode. It can be operated in the automatic or mechanized mode. It can also be operated on semi-automatic (hand-held) SAW guns with the delivery of pressurized or gravity flux fed. This process is not suitable for flat or horizontal filler welding positions through the horizontal position have been done with a special arrangement in order to support the flux.
In this welding process, the arc zone and weld pool are protected from atmospheric contamination, due to the blanket of granular flux consisting of lime, silicon, manganese oxide, calcium fluoride, and some other compounds. The molten flux becomes conductive and creates current between the electrodes and the base metal. The thick flux layer covers the metal completely, preventing sparks and spatters, and supporting the intense ultraviolet radiation and fumes which are part of the welding process.
SAW was the first patent in the year 1935 and covered an electric arc beneath a bed of granulated flux. It was originally developed by Jones, Kennedy, and Rothermund.
Diagram of submerged arc welding:
Read more: Understanding shielded arc welding (SMAW)
The followings are the applications of SAW:
SAW process is suitable for welding carbon steels (structural and vessel construction). It is also used on low alloy steels, stainless steels, nickel-based alloys, and surfacing applications.
The Submerged Arc Welding can be used to weld pressure vessels like boilers.
A lot of structural outlines, pipes, earthmoving tools, shipbuilding, railroad construction, and locomotives.
Finally, submerged arc welding can be used to repair machine parts.
The process has some distinct features that make it differs from other arc welding process, which include:
- Welding head: this feeds the flux and the filler metal to the welding joint.
- Flux hopper: this helps to store the flux and controls the rate of flux deposition to the welding joint.
- Flux: the granulated flux protects the weld from atmospheric contamination. It also cleans the weld metal and modifies its chemical contamination. Though some other arc welding processes like MIG, SMAW offers this.
- Electrode: the filler material is a standard wire as well as other special forms. The thickness of these wires is normally 1.6mm to 6mm.
Read more: Understanding tungsten inert gas welding (TIG)
Machine parts of SAW
The submerged arc welding is built with main parts or equipment like Welding head, Flux hopper, Flux, Electrode wire feed unit, Electrode, and Flux recovery unit. Welding head can be used to supply filler as well as flux metal to the joint for welding. Other common parts of the machine include:
- Consumable Electrode
- Power Sources
- Granular Flux
- Base Metal
- Electrode Holder
Submerged arc welding machine:
Read more: Understanding electro slag welding
Working principles of SAW
Just like other arc welding processes, SAW also transferred current to the electrode from either AC or DC welding machine. It separately deposited flux to the weld zone before the joining takes place. This flux is a non-conductor of electricity when cold but becomes a good conductor when melted with the arc heat. It also allows the current flow between the electrode and the workpiece. The flux which is visible to the atmosphere, remains granular (unchanged), making it to be reused. The lower melted flux becomes slag, making it a waste material and must be removed after welding,
Using a predetermined speed, the electrode is continuously fed into the joint. Whilst in semi-automatic welding sets, the welding is done manually along the joint. In automatic, a separate drive moves either the welding head over the stationary job or the job rotates under the stationary welding head.
Read more: Understanding plasma arc welding (PAW)
Watch the video below to learn the working of SAW:
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Read more: Understanding arc stud welding and its techniques
Advantages and disadvantages of submerged arc welding
Below are the advantages of SAW:
- High deposition rate.
- The process is automated.
- Less smoke is obtained.
- Edge training is not required.
- It can be done indoors, and/or outdoor.
- No chance for oxide sparks because it’s submerged within a flux blanket.
Despite the good benefits of SAW, some limitations still occur. Below are the disadvantages of SAW:
- The process is incomplete to some particular metals.
- It can be imperfect to direct seams vessels, and pipes.
- Flux usage can be tedious.
- A health problem can be occurred due to the flux.
- Slag elimination is desirable after welding.
Read more: Understanding stud welding
That is all for this article, where the definition, applications, diagram, equipment, working, advantages and disadvantages are being discussed. I hope you got a lot from the reading, if so, kindly share with other students. Thanks for reading, see you next time!