Top-Rated Free Essay
Preview

Gas Tungsten Arc Welding

Good Essays
1154 Words
Grammar
Grammar
Plagiarism
Plagiarism
Writing
Writing
Score
Score
Gas Tungsten Arc Welding
Gas Tungsten Arc Welding
The Process
Gas Tungsten Arc Welding, also known as Tungsten Inert Gas Welding, is an arc welding process that uses a non-consumable tungsten electrode to produce a weld. The weld area is protected from atmospheric contamination by an inert shielding gas, such as argon or helium, and filler metal is normally used, except in autogenous welds. A constant-current welding power supply produces energy which is conducted across the arc through a column of highly ionized gas and metal vapors known as a plasma.

GTAW is most commonly used to weld thin sections of stainless steel and non-ferrous metals such as aluminum, magnesium, and copper alloys. The process grants the operator greater control over the weld than competing processes such as shielded metal arc welding and gas metal arc welding, and allows for stronger, higher quality welds. However, GTAW is comparatively more complex and difficult to master, and furthermore, it is significantly slower than most other welding techniques.
How it works
Manual Gas Tungsten Arc Welding is considered the most difficult of all the welding processes commonly used in the industry. Because the welder must maintain a short arc length, great care and skill are required to prevent contact between the electrode and the workpiece. GTAW normally requires two hands, since most applications require that the welder manually feed a filler metal into the weld area with one hand while manipulating the welding torch in the other. However, some welds combining thin materials (known as autogenous or fusion welds) can be accomplished without filler metal; most notably edge, corner, and butt joints.
Striking the Arc
To strike the welding arc, a high frequency generator (similar to a tesla coil) provides an electrical spark. The spark creates a path through the shielding gas and allows initiation of the arc while the electrode and the work piece are separated, typically about 1.5-3mm apart. An alternate way to initiate the arc is to scratch or touch the workpiece with the powered electrode which initiates the arc; this is known as “scratch starting”. Scratch starting, however, may cause contamination of the weld and electrode. Some GTAW equipment is capable of a mode called “touch start” or “lift arc”; here the equipment reduces the voltage on the electrode to only a few volts, with a current limit of one or two amps (well below the limit that causes metal to transfer and contamination of the weld or electrode). When the GTAW equipment detects that the electrode has left the surface and a spark is present, it immediately (within microseconds) increases power, converting the spark to a full arc. The electric arc can reach temperatures of at least 2500°C.
Welding
Once the arc is struck, the welder moves the torch in a small circle to create a welding pool. While maintaining a constant separation between the electrode and the workpiece, the operator then moves the torch back slightly and tilts it backward about 10–15 degrees from vertical. Filler metal is added manually to the front end of the weld pool as it is needed. The filler rod is withdrawn from the weld pool each time the electrode advances, but it is never removed from the gas shield to prevent oxidation of its surface and contamination of the weld.
Tools Used
Power Supply
Gas tungsten arc welding uses a constant current power source, meaning that the current (and thus the heat) remains relatively constant, even if the arc distance and voltage change. This is important because most applications of GTAW are manual or semiautomatic, requiring that an operator hold the torch. Maintaining a suitably steady arc distance is difficult if a constant voltage power source is used instead, since it can cause dramatic heat variations and make welding more difficult.
Electrode
The electrode in GTAW is made of tungsten or a tungsten alloy because tungsten has the highest melting point among pure metals, at 3,422°C (6,192°F). As a result the electrode is not consumed during welding, though some erosion, called “burn-off”, may occur.
Shielding Gas
Shielding gases are necessary in GTAW to protect the welding area from atmospheric gases such as nitrogen and oxygen, which can cause fusion defects, porosity, and weld metal embrittlement if they come into contact with the electrode, the arc or the welding metal. The gas also transfers heat from the tungsten electrode to the metal, and it helps start and maintain a stable arc. Argon is the most commonly used shielding gas for GTAW. When used with alternating current, the use of argon results in high weld quality and good appearance. Another common shielding gas, helium, is most often used to increase the weld penetration in a joint, to increase the welding speed, and to weld metals with high heat conductivity, such as copper and aluminum. However, using Helium can make it difficult to strike the arc and decrease the weld quality. Argon-helium mixtures are also frequently utilized in GTAW because it combines the benefits of both. The mix is normally about 75% (or more) helium.
Safety Gear
Protective Clothing
Welders wear protective clothing, including light and thin leather gloves and protective long sleeve shirts with high neck collars, to avoid exposure to strong ultraviolet light.
Masks/Helmets
Because of the absence of smoke in GTAW, the electric arc light is not covered by fumes and particulate matter, and thus, is a great deal brighter, making operators especially susceptible to the effects of strong ultraviolet light exposure. Opaque full face and neck Helmets with dark eye lenses are worn to prevent this exposure to ultraviolet light, and in recent years, new helmets often feature a liquid crystal-type face plate that self-darkens upon exposure to the bright light of the struck arc.
Safety Precautions
Welding Curtains
Transparent welding curtains, made of a polyvinyl chloride plastic film, are often used to shield nearby workers and bystanders from exposure to the UV light from the electric arc.
Ventilation
Welders are also often exposed to dangerous gases and particulate matter. Although smoke is not produced, the brightness of the arc in GTAW can cause surrounding air to break down and form ozone which creates nitric oxides. Inside the lungs the ozone and nitric oxides react with the lung tissue and moisture to create nitric acid and ozone burn. Although the levels of ozone and nitric oxides are moderate, precautions, such as: limiting duration of exposure, limiting repeated exposure, correctly extracting fumes and ensuring air circulation, are required to keep relatively healthy lungs. If precautions are not taken welders may suffer emphasyemia and odema of the lungs which, as well as shortening life span, can result in death.
Cleaning Products
The brightness and heat from the arc can cause cleaning and degreasing agents to break down and react to form poisonous fumes. Cleaning operations using these agents should not be performed near the site of weld.

You May Also Find These Documents Helpful

  • Satisfactory Essays

    Under Water Welding

    • 346 Words
    • 2 Pages

    Welding is divide into two category’s wet under water welding and dry welding, they are both under the category of hyperbaric. Under water welding is very dangerous. One of the risk of underwater welding is getting…

    • 346 Words
    • 2 Pages
    Satisfactory Essays
  • Good Essays

    Welding Career Essay

    • 910 Words
    • 4 Pages

    Welding with a rod is called SMAW (Stick Metal Arc Welding), you will absolutely need to know the type of welding if you are planning to be a pipeliner. SMAW is one of the hardest types of welding to master, and it is the most effective. Most welders start off by learning how to weld with a rod. There are also two more types of welding along with brazing and oxyacetylene cutting. GTAW better known as tig or tungsten arc welding is absolutely the hardest type of welding to learn mostly because you need very steady hands and good hand-eye coordination. GTAW is used to weld very thin metals such as aluminum, copper, etc. GMAW is the easiest type of welding and can be used for mostly anything. Some beginners use this if they cant get SMAW down, this is just an easier route. GMAW isn’t the strongest weld to put on something you want to hold a lot of pressure or something you want to last for a very long…

    • 910 Words
    • 4 Pages
    Good Essays
  • Good Essays

    Why You Should Weld

    • 406 Words
    • 2 Pages

    Don't be afraid of the future, Build it. Welding is a neat and fun activity that you can build cool things from. Welding is not hard and you can learn to do it. You can do this on your free time. From welding projects and other things you can make money from them by selling them.…

    • 406 Words
    • 2 Pages
    Good Essays
  • Better Essays

    In assembly Reynolds 853 steel is suitable for TIG welding and brazing, using lugged or lugless construction. The production process ensures tight tolerance, gauge tubes. The strength to weight ratio of 853 is close to that of quality titanium frames. It however can not be brazed.…

    • 2164 Words
    • 9 Pages
    Better Essays
  • Good Essays

    Mig Welding

    • 952 Words
    • 4 Pages

    Metal Inert Gas (MIG) welding, also sometimes called Gas Metal Arc Welding (GMAW) is a process that was developed in the 1940s for welding aluminum and other non-ferrous metals. MIG welding is an automatic or semi-automatic process in which a wire connected to a source of direct current acts as an electrode to join two pieces of metal as it is continuously passed through a welding gun. A flow of an inert gas, originally argon, is also passed through the welding gun at the same time as the wire electrode. This inert gas acts as a shield, keeping airborne contaminants away from the weld zone.…

    • 952 Words
    • 4 Pages
    Good Essays
  • Good Essays

    History of Welding

    • 917 Words
    • 4 Pages

    In 1802, Russian scientist Vasily Petrov discovered the electric arc[4] and subsequently proposed its possible practical applications, including welding. In 1881–82 a Russian inventor Nikolai Benardos created the first electric arc welding method known as carbon arc welding, using carbon electrodes. The advances in arc welding continued with the invention of metal electrodes in the late 1800s by a Russian, Nikolai Slavyanov (1888), and an American, C. L. Coffin (1890). Around 1900, A. P. Strohmenger released a coated metal electrode in Britain, which gave a more stable arc. In 1905 Russian scientist Vladimir Mitkevich proposed the usage of three-phase electric arc for welding. In 1919, alternating current welding was invented by C. J. Holslag but did not become popular for another decade.[5]…

    • 917 Words
    • 4 Pages
    Good Essays
  • Good Essays

    Welders actually use many other tools than just a standard TIG, MIG, and stick welder. Welders on a daily basis operate safety equipment and use safe work habits, such as wear safety glasses, inspect their clothing, and wear the proper shade tint while welding. This is very important because welders can get hurt very easily by not wearing the proper safety equipment. They also examine work pieces with straight edges or templates to ensure conformance to specifications. Welders also use hand and power tools to clean welds and work on parts. Welding also involves cutting the material. Welders cut material by suing a plasma cutter or with a torch. The plasma cutter is more efficient, but the torch is much more exciting in my opinion. The main thing a welder performs is welding. Welders will perform many different types of welds. The most common type of welding is SMAW welding, which stands for shielded metal arc welding. Stick welding involves using a shade 9 or 10 level tint. Stick welding is done by turning on the machine and attaching the clamp to another piece of metal. Next the welder has to strike the arc by touching the electrode to metals that needed to be welded. A MIG welder is actually stronger than a stick welder, just from my experience welding and learning from others. MIG welding is commonly referred to as wire welding. This is also called GMAW welding, which stands for gas metal arc welding. This type…

    • 1652 Words
    • 7 Pages
    Good Essays
  • Better Essays

    Welding Risk

    • 1418 Words
    • 6 Pages

    Ventilation is a major factor when welders are in confined spaces. Ventilation exhausts the fumes into the open where it will not harm people. Welders must also worry about electrocution. Any person who has welded for some time knows that it doesn’t take much to get shocked all it takes is for your body to ground out on the metal that is being welding. A welder can get grounded to metal easily if it is raining or the metal is wet and you have exposed skin touching the item being welded.…

    • 1418 Words
    • 6 Pages
    Better Essays
  • Better Essays

    Arc Welding

    • 1103 Words
    • 5 Pages

    •Stick SMAW (shielded metal arc welding) •Mig GMAW (Gas Metal Arc Welding) •Flux-Core FCAW (Flux-core Arc Welding) •Tig GTAW (Gas Tungsten Arc Welding)…

    • 1103 Words
    • 5 Pages
    Better Essays
  • Good Essays

    Becoming An Arc Welder

    • 1778 Words
    • 8 Pages

    One type of popular welding that you can learn to do is arc welding. Arc welding is highly used because it is cheaper to do than the other types of welding. The arc welder has a device that has an electric current that goes through it. A arc welder can give a weld that looks like an arch. Another highly used type of welding is MIG welding. MIG stands for metal inert gas. MIG welding is a type of welding where the welder uses a gas to shield the weld metal. MIG welding can be used for many different jobs. There is also different types of MIG welding. One more commonly used type of welding is TIG welding. TIG stands for tungsten inert gas. TIG welding is similar to MIG welding. The major difference between the two types of welding is that TIG welding uses a tungsten current form while MIG uses a metal electrode. There is also many different types of TIG welding that you can learn how to do. There are many other types of welding including heliarc, hydrogen arc, plasma arc, water jet cutting, percussion welding, thermite welding, forge welding and magnetics pulse welding. Each type of welding has its own use and its own types of materials that you would have to buy for the…

    • 1778 Words
    • 8 Pages
    Good Essays
  • Satisfactory Essays

    Linear Archetype Joint

    • 78 Words
    • 1 Page

    I learned that with welding with TIG on aluminum that if you bump the electrode and the fillet wire together it could mess up you current weld or the plate itself. When welding on aluminum while doing a tee joint its important to have the right arc length, torch angle, and amperage. Also I learned that when welding an aluminum tee joint it good to keep the beads small and get the puddle to flow into the corners.…

    • 78 Words
    • 1 Page
    Satisfactory Essays
  • Satisfactory Essays

    Injury In Welding

    • 345 Words
    • 2 Pages

    Most of the tasks welders perform are dictated by the design of the work piece. A lot of the time, the material is big, heavy, and is covered with dirt and rust. There are lots job aids such like jigs, and pipe holders available to help welders do their job and minimize the risk of injury. Special chairs and creepers are available to provide support while performing welding tasks so that bad posture is avoided.…

    • 345 Words
    • 2 Pages
    Satisfactory Essays
  • Good Essays

    Spot Welding Essay

    • 702 Words
    • 3 Pages

    When I think of welding the first place I think of is John Deere. Now with all of the technology that we have it will not be long before it is the only thing making items. Welding producers have been working to create robotic welding software to work on their own. As people continue to create these robots they are using more flexible systems to create a larger quality of products to make. Most of the welding jobs are beginning to be take over with robotics; while all of the floor workers are used to putting their welding skills to the test they have transferred to automatic industrial welding robotics. While spot welding is a huge step in welding, these welds may not be as precise when put into human hands. The automatic machines have been developed to have extreme precise spot welds to help strengthen the weld. This is possible due to the extreme about of analog and digital signals; since these are so precise…

    • 702 Words
    • 3 Pages
    Good Essays
  • Good Essays

    Welding

    • 621 Words
    • 3 Pages

    The dictionary defines electric arc welding as “A technique in which metals are welded using heat generated by an electric arc.”…

    • 621 Words
    • 3 Pages
    Good Essays
  • Satisfactory Essays

    Oct 8, 2014 – Mumbai, India : Marketreportsonindia.com presents a report on “Welding Machinery Market in India to 2018” offers the most up-to-date market data on the actual market situation, trends and future outlook for welding machinery in India.…

    • 478 Words
    • 2 Pages
    Satisfactory Essays

Related Topics