gas tungsten arc welding (GTAW)
GTAW or gas tungsten arc welding process is a manual welding process that can only be done by an experienced welder. GTAW produces excellent quality and excellent welding quality. This process is often used for pipe welding or pressure vessels with special materials such as high-temperature steel, stainless steel or high strength steel. This GTAW welding process is also often used with the SMAW process, which is in the root (which requires good and clean quality) using the GTAW process and is followed by a faster SMAW process.
GTAW (Gas Tungsten Arc Welding) is an electric arc welding process using non-melted electrodes. In this GTAW welding, the electrode or tungsten is only functioning as an arc producer when it comes to contact with the workpiece, while the filler material is the filler rod. This GTAW welding is also often referred to as Argon welding, it is because the protective gas used is Argon gas. GTAW is also called Las TIG which has a Tungsten Inert Gas extension, this difference is just a mention. If GTAW is more frequent for American terms while TIG is for the European region.
Unlike simple welding methods which produce slag, or chips of metal that tend to chip off of the welds, GTAW is a much “cleaner” method of welding useful in situations requiring no welding slag, such as applications where a neat and attractive appearance is critical. With GTAW, the welder must maintain a very short arc length while preventing contact between the electrode and the work itself, requiring a great deal of training, skill, and care. Two hands are usually required with GTAW, as one hand will be operating the welding torch while the other hand feeds the filler metal into the weld being created.
Welding Equipment for GTAW ( Gas Tungsten Arc Welding):
1. GTAW Welding Machine
GTAW gas welding machines have two types of currents, namely AC and DC currents. In general, the welder most often performs DC welding. The DC current welding machine has two types of polarity, namely DCEN Polarity (Direct Negative Current Electrode) and DCEP (Positive Current Electrode). DCEN polarity is used for welding which requires deep penetration such as root on the Joint V joint.
2. Welding Torch
Welding Torch is a tool that functions as a handle during the welding process. Welding torch consists of several components such as a ceramic cup (which serves as the outlet of the protective gas), the place of tungsten, electric current conductors and protective gas hoses.
3. TIG Gas Cylinder
The gas cylinder used for GTAW welding is useful as a protective gas used for the GTAW welding process. some types of protective gases most often used by welder are Argon, Helium or Argon mixture with Helium. Each of these protective gases has different benefits and prices.
4. GTAW Welding Wire (Welding Rod)
The welding wire used consists of various types, namely, there are types of ER 70 S, ER 308 L – 16, ER 309 Mo L, ER 309 Mo L- 16/17, ER 316 L – 16, ER 312-16.
5. GTAW Tungsten Electrodes
In the selection of GTAW tungsten electrodes also various kinds, the selection is adjusted to the type of material used. Therefore it should not be arbitrary in choosing tungsten so that the results of the weld produced can be maximal and in accordance with the welding standards.
The advantages of GTAW – Gas Tungsten Arc Welding
- The weld results are stronger because they can penetrate deeper and have higher corrosion resistance.
- Welding results are very clean.
- Welding results do not need to be cleaned because they do not produce slag.
- Does not produce spatter or welding sparks so the weld is cleaner.
- The gas flow makes the area around the metal liquid not contain air so that it prevents fouling by nitrogen and oxygen.
- The welding process can be observed easily, not much smoke arises.
- Deformation is rare because the heat center is very small.
The disadvantages of GTAW – Gas Tungsten Arc Welding
- Low weld productivity.
- During the welding process, burn-back can occur.
- Porosity weld defects or small holes often occur if the welding surface shielding gas cannot protect maximally.
- Tungsten inclusion can occur.
If you need to join or repair the pipeline with the “golden joint” condition, I recommend choosing the GTAW process. Since the GTAW welding is more difficult than SMAW welding, GTAW welder has higher salary than SMAW welder.
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