15 Main Advantages and Disadvantages of Submerged Arc Welding | Applications & Uses for SAW
What is Submerged Arc Welding (SAW)? | Advantages and Disadvantages of Submerged Arc Welding |How Submerged Arc Welding Works | Applications for Submerged Arc Welding
What is Submerged Arc Welding (SAW)?
Submerged arc welding is a type of arc welding in which arcs are formed between a flux-covered bare metal electrode(s) and the weld pool.
The arc and molten metal are shielded by a blanket of granular flux delivered from a hopper through the welding nozzle.
The technique is employed without pressure and filler metal from the electrode, as well as occasionally from a supplemental source (welding rod, flux, or metal granules).
SAW can be used in three ways: semiautomatic, automatic, and machine. It may operate with either a CV or a CC power supply.
SAW is widely utilized in the manufacture of pressure vessels and pipes in shops.
How Submerged Arc Welding Works
Submerged arc welding (SAW) is a popular arc welding technique. A continuously fed consumable solid or tubular (metal cored) electrode is required for the process.
The molten weld and arc zone are shielded from ambient pollution by being “submerged” in granular fusible flux made up of lime, silica, manganese oxide, calcium fluoride, and other chemicals.
When the flux melts, it becomes conductive and creates a current path between the electrode and the work.
This thick coating of flux completely covers the molten metal, preventing spatter and sparks and dampening the powerful ultraviolet radiation and fumes produced by the shielded metal arc welding (SMAW) process.
SAW guns are typically operated in an automated or mechanized mode, however semi-automatic (hand-held) SAW guns with pressurized or gravity flux feed supply are also available.
Typically, the procedure is limited to flat or horizontal-fillet welding positions (although horizontal groove position welds have been done with a special arrangement to support the flux).
DC or alternating current (AC) power can be employed, and combinations of the two are typical on multiple electrode systems.
Constant voltage welding power supply are the most often utilized, however constant current systems with a voltage detecting wire-feeder are also available.
Applications for Submerged Arc Welding
Submerged Arc Welding is used to join carbon, steel, aluminum, titanium, and low-alloy materials.
Used in the welding pipe, structural manufacturing, vessel manufacturing, storage tanks, and ship construction sectors.
It has the ability to weld corrosion-resistant metals, heat-resistant steels, and other carbon steels.
Submerged Arc Welding is also used for monel and nickel welding.
Used mostly for down hand welding applications with plate thicknesses ranging from 5 to 50mm.
Advantages and Disadvantages of Submerged Arc Welding
Advantages of Submerged Arc Welding
1. Very High Deposition rates
Submerged Arc Welding is also referred to as SAW because of the material deposition.
The objective is to deposit a layer of molten weld metal onto the base material to be welded or otherwise adhered.
This can be done using three-phase currents, synchronized servomotors, or a combination of both.
The thickness of the deposited metal layer can be designed using design parameters such as electrode size and wire feed speed (or flux weight).
2. High and consistent quality
The submerged arc welding process uses the mechanical forces of the welding machine to pull the electrode and filler metal into the pool of molten flux.
The molten metal flux completely covers the weld pool which prevents contamination with excess impurities, air, and slag.
3. Deep weld penetration
The weld penetration of SAW can be as deep as 75 mm into materials with thicknesses less than 25 mm.
4. High-speed welding of thin sheet steels
SAW produces a very deep weld penetration.
One of the most common applications for this process is the welding of thin sheets or plate material.
Other processes such as gas metal arc welding or resistance spot welding cannot achieve the same level of weld penetration in thin sheets as submerged arc can.
5. SAW is suitable for both indoor and outdoor works
SAW can be used in both indoor and outdoor works.
It can also be used for pressure vessels, offshore platforms, and gas pipelines.
It is ideal for welding carbon, low alloy steels, stainless steels as well as other materials.
6. Minimal welding fume or arc light is emitted
This process requires high power and consequently generates more fume.
As the weld is submerged in flux, the welding fumes are completely shielded, reducing the impact of fumes on the weld area.
7. SAW is faster than traditional welding processes
The speed of SAW can increase by 3 to 4 times compared to that of conventional welding processes such as GMAW and stick welding due to its short-circuiting mechanism.
8. Electrical efficiency
Some studies have shown a high deposition rate and therefore lower energy input in comparison to other weld processes, such as gas tungsten arc welding, gas metal arc welding, or plasma arc welding.
Disadvantages of Submerged Arc Welding
1. High current and 100% duty cycle
The power consumption of SAW is 100% duty cycle (current remains on continuously, cannot be turned off).
The welding electrode requires a high current in order to ensure a complete shield of flux.
So, if the power supply is not capable of handling the required current, there will be smoke and fumes emitted.
2. The weld is hidden by flux making it harder to control
The flux produces a build-up on the surface of the weld, which is a concern for weld inspection and quality assurance.
3. Equipment is costly and not very portable
SAW equipment can be costly and are not very portable, you might need a welding machine with a high-power supply to use it.
4. Limited to shop work in the flat position
SAW cannot be used for applications such as straight line, swing, or vertical welding.
5. Limited to flat work when welding in the horizontal position
SAW can only be used to weld in the horizontal position
6. Does not penetrate through thick materials
SAW does not penetrate through thick materials which makes it unsuitable for highly contaminated applications or those with significant amounts of slag or impurities.
7. Requires backing strips for proper root penetration
SAW is a short-circuiting process, so cathodic protection in the form of backing strips or anodes are required for adequate root penetration.
8. Difficult to control heat input and deposit thickness
The deposition rate of SAW is highly dependent on electrode size and therefore requires high-power equipment for this to occur.
High power equipment is also required to absorb the large amount of heat that is produced during SAW welding.
Submerged Arc Welding FAQs
1. What is submerged arc welding?
Submerged Arc Welding (SAW) is a welding technique that includes forming an electric arc between a continuously fed electrode and the workpiece to be welded.
When molten, a blanket of powdered flux surrounds and covers the arc, providing electrical conduction between the metal to be connected and the electrode.
2. Why is it called submerged arc welding?
Submerged arc welding (SAW) gets its name from the fact that the weld and arc zone are both submerged beneath a blanket of flux.
When the flux material is melted, it becomes conductive, allowing current to flow between the electrode and the workpiece.
3. What are the advantages of submerged arc welding?
The main benefits of SAW, or submerged arc welding, are excellent quality metal welds., extremely fast deposition rate, and speed, the finished weld is smooth and homogeneous, with no spatter.
4. What are the applications of submerged arc welding?
Submerged arc welding is most commonly used to weld low carbon and low alloy steels, but with the development of suitable fluxes, it may also be used to effectively weld stainless steels, copper, aluminum, and titanium base alloys.
5. What are the five major advantages of the submerged arc welding process?
Some advantages of Submerged Arc Welding include;
- Minimal welding fume is emitted.
- Less distortion.
- Strong, sound welds are readily made.
- SAW is suitable for both indoor and outdoor works.
- High deposition rates are possible.
- Deep weld penetration.
- Minimal edge preparation.
6. What is the working principle of submerged arc welding?
Submerged-arc welding (SAW) is the process of forming an arc between a continuously fed wire and a workpiece.
A covering of powdered flux forms a gas shield and slag for the weld zone. It is not necessary to use a shielding gas.
7. In which position is submerged arc welding is done?
SAW is perfect for butt and fillet welds both longitudinally and circumferentially. Due to the high fluidity of the weld pool, molten slag, and loose flux layer, welding is typically performed on butt joints in the flat position and fillet joints in both the flat and horizontal-vertical orientations.
8. What is the main purpose of submerged arc flux?
The arc and weld pool are immersed in a flux to shield the molten weld metal from the atmosphere, where it could pick up unwanted gasses and cause nonmetallic inclusions or porosity.
SAW is not a forging technique like ERW, and there is no mechanical pressure exerted during the welding process.
9. Is it necessary to apply pressure in submerged arc welding?
Submerged arc welding does not require additional pressure to weld because the electrode generates it. This application is ideal for swiftly welding thin metal sheets together and creating a secure fusion between welds.
10. What is the difference between flux core welding vs mig?
MIG welding use a solid wire electrode, whereas Flux Core employs a tubular welding wire. A tubular welding wire differs from a solid welding wire in that it is hollow.
It’s made of metal on the outside and flux in the middle. Solid wire cannot be used to weld with flux core welds.
11. Is flux core welding any good?
Self-shielded flux-cored welding can be an excellent process to use for welders of all skill levels who frequently need to weld outside or on dirty material.
Self-shielded flux-cored welding is a wire welding process in which a continuous hollow wire electrode is fed through the welding gun into the weld joint.
12. “Can a flux cored wire SAW system be used to weld low carbon steel?”
The flux cored wire is only meant for mild steel and stainless steel, so using it on low-carbon steel will probably cause contamination of the weld.
A solid wire system is required to prevent contamination from occurring.
13. What is the strongest type of weld?
A type of weld formed using the welding technology of Tungsten Inert Gas (TIG) Welding, commonly known as GTAW welding, produces the utmost strongest weld that can be made in everyday applications. TIG welders are well-known for producing clean, robust welds.