Types of welding gases and their use:
While the old welders had little information about the use of gases in the welding process. The emergence of MIG and TIG welding machines during the last 70-80 years, the need for welding gas a> as a common item in most workshops.
Why are there different types of welding gases? What are they used for?
As we look at the gases and gas combinations used in welding, it is amazing to see how far we have come in the short time since it was first implemented.
When air enters the arc during welding, it causes air bubbles to form within the molten metal, creating a weak and poorly shaped weld. You cannot do TG or MIG welding without shielding gas unless the filler material used is flux coated. This is the purpose of a shielding gas and it removes impurities in different ways.
Most shielding gases are neutral because they are ideal for shielding the welding process and remain stable under difficult welding conditions. They also enhance the weld in various ways depending on the gas used, including greater penetration, greater fluidity during melting, and a smoother surface on the bead.
Purging gases are used to coat the underside of the material you are welding in the same way that a shielding gas would, only it is done separately from the normal welding process.
As you weld the top of a joint, the bottom of the joint is closed and there is a flow of gas that cleans it. It is often used with stainless steel cases and can be the same type of gas or a different gas than that used above the connection.
Special welding, such as gas welding and brazing, requires gas to heat the metal or filler rods to achieve the weld. This replaces the need for an arch.
Certain types of welding require heating of the metal before welding, for which this gas is used. A gas is simply a fuel combined with air or oxygen and ignited by a flame to heat or melt metal.
A process in which tanks and enclosed spaces are filled with gas after completion to keep air and other contaminants from harming the finished product.
Sometimes it is used to completely fill completed projects. At other times, the gas is added to the air-filled tank, forming a mixture, to keep the tank clean of other gases or reactions.
Carbon dioxide is what we use when we exhale. It is also created from organic materials. Carbon dioxide used in workshops and other industrial places is taken from natural gas and then compressed in a pressurized tank.
What is the purpose of welding with carbon dioxide gas?
Carbon dioxide is used as a protective gas. Its purchase price is cheap, but it does not produce the same quality weld as argon and has more problems during the welding process, such as welding sparks. That is why they are used more in combinations than in pure form.
Applications of using its pure form include arc welding, MIG welding of carbon steel and plasma shielding.
Compressed air is what we breathe but in a compressed form. This composition contains 78% nitrogen, 21% oxygen and 1% other particles. When compressed, a large volume of air is compressed into a smaller space than it would normally fit.
It is pushed into the tank and creates significant pressure. When it’s released, it pops out with urgency in the work you’re using it for.
The purpose of welding with compressed air:
Although air is not used in the welding process because it contaminates the weld, it is used in many other ways in welding work. Many shops use compressed air to remove dust, stains and other dry materials from around the shop. Air nozzles attached to compressors with hoses shoot air out to remove dust.
It is also combined with fuel to create flames that preheat the metal before welding. Uniform heat transfer or less transfer from cold to hot is essential for certain materials during welding, including high carbon steel. This is why a preheater is sometimes necessary.
Almost all life depends on this vital gas. This gas is odorless, colorless and tasteless, and many people consider it a more passive and friendly gas than other gases. This gas is actually one of the most reactive gases in the world. This gas is found in most living organisms and combines with any other gas except inert gases.
Purpose of welding with oxygen:
This gas is combined in small amounts with shielding gases, to protect the molten pool and increase the speed of the welding process. It is used to boost heat with fuel, for gas welding and cutting metals, and when combined with acetylene, it produces a flame just hot enough to weld steel.
Oxygen gas welding also provides an adequate shield to protect some metals, eliminating the need for shielded welding wire.
This highly flammable gas is widely used to produce chemicals for other industrial purposes. When mixed with air, it is highly flammable.
Purpose of welding with acetylene:
Acetylene is used as fuel for oxygen cutting and oxygen welding. When combined with oxygen, it is the most effective gas for forming a flame hot enough to easily cut and weld most metals. This fuel is more expensive than other types of fuel, but it is the best type of fuel to use.
Did you know that helium is one of the only substances that does not freeze? Bring it to less than 450 F and it turns into a liquid. It is used in many scientific experiments and in rockets, decorative and scientific balloons.
We’ve all had our share of fun using helium with balloons or as a sound modifier, but it’s actually a very valuable gas that’s vital to human progress. It is the second most common gas in the world, but on Earth, it is not as abundant as other gases and its production is challenging. Because more than six million cubic meters of it are consumed every year, its supply is gradually decreasing. Several space trips may soon be needed to collect helium.
The purpose of welding with helium gas:
Helium is used as a shielding gas, both in pure form and as a mixture with other gases in MIG and TIG welding. This gas provides deeper penetration and a higher heat input to the boil.
This gas forms a good compound when used with argon. Argon is good at stable arc starts and helium adds the extra heat needed for special applications such as aluminum welding and especially TIG welding.
As the most abundant gas in our atmosphere, which covers nearly 80% of the earth’s surface and is a part of every living organism, nitrogen is an essential requirement. It is used to protect many products such as food, engines, tanks and anything that can be damaged by excess oxygen or other gases.
The purpose of welding with nitrogen:
Nitrogen can be used alone as a shielding gas for laser welding and plasma cutting and is used in some heat treatments. It is also combined with other shielding gases for special applications, but is not suitable for carbon steels. When shielding nitrogen-rich metals, it increases the mechanical properties of the alloy and can deepen penetration while making the arc stable.
Nitrogen is also used as a covering gas after welding is completed inside tanks and closed spaces. to preserve the material until it is used with its intended product.
As the simplest of gases, hydrogen is the fuel that stars like the sun use to burn. It is abundant in the earth, easy to produce, and burns without GHG emissions while producing water as its final byproduct.
In addition to being a major element in water, in its crude form, it is heavily used for commercial purposes. It is used in food products such as peanut butter and oils and to create essential chemicals such as ammonia.
Purpose of welding with hydrogen:
Surprisingly, hydrogen is used as a shielding gas in combinations with argon or carbon dioxide. Some people fear this thought because it can explode.
There is a specialized welding process called atomic hydrogen welding that uses 100% hydrogen in its raw form and produces an arc temperature range between 6100 F and 7200 F. This gas is used for welding high melting point materials such as tungsten. This type of hydrogen welding is dangerous.
However, given the percentage of hydrogen used in standard welding methods, it is actually very safe. When hydrogen is used in the shielding gas, there is a risk of weld cracks, but applying protective layers to the weld solves this problem. However, hydrogen is an excellent shielding gas choice due to its excellent heat capacity in welding. This increases penetration and produces a cleaner weld than other gases.
There is a wide range of gases to use. All of them have strengths and weaknesses. Combination gases provide a good balance to utilize the strengths of different gases in one product and provide excellent results.
Each gas has several properties that, when combined, result in a gas that uniquely welds a material in the desired manner.
Argon and carbon dioxide:
This protective compound produces a smooth weld with minimal sparking. This composition is in the range of 95% argon with 5% carbon dioxide and 80% argon with 20% carbon dioxide. The thinner the steel section, the less carbon dioxide composition is used.
Argon, carbon dioxide and oxygen:
Similar to the combination of argon and carbon dioxide. The weld is clean and the added oxygen, less than 5% of the composition, increases the fluidity in the weld pool and the speed of movement during the welding process.
Helium and argon:
This helium-rich mixture is primarily used for aluminum and other alloys to create deep penetration and wide welds.
Argon, helium and carbon dioxide:
A wide range of different compositions are available, some with helium content and others predominantly argon. They are used with a wide list of different metals including carbon steel, stainless steel and aluminum.
Argon and oxygen:
The oxygen content in this composition is low. This type of combination is primarily used for welding steel with optical sensors and helps to combine the materials.
Argon and hydrogen:
This combination accelerates TIG welding methods. while also providing a cleaner weld.
Nitrogen and hydrogen:
This compound is specifically used to protect stainless steels. This combination increases the penetration and speed of the welding process while also increasing the mechanical properties of the stainless steel.
All gases used in welding have unique risks due to their characteristics. While most are not flammable, any flammable gas used in a welding shop, especially acetylene, must be handled with great care.
Flammable gases should be kept away from your welding area unless you are using them. When using them, have a type B fire extinguisher nearby.
If your fire extinguisher does not have any type on it, a Type B fire extinguisher will be filled with carbon dioxide or some type of dry chemical.
While inert gases pose little threat because they are non-flammable and do not react with anything, they can cause asphyxiation if you weld in an enclosed space for long periods of time. If you have to weld in a confined environment, make sure you have the proper precautions in place. Gas detectors, extraction fans, boiling points and regular breaks are great ways to minimize the risk.
The tanks are designed to be strong enough to withstand impact well and not change, but you have to move the welding tank with care. The valve at the top of the tank is a weak point. If it breaks, you could have a powerful projectile on your hands due to the pressure inside those tanks.
Gases are an essential part of any welder’s work. Some welding gases are great for multiple applications, such as pure argon, for most TIG welding projects, and a mixture of argon with carbon dioxide, which is used for most MIG welding. Knowing the different gases and their purposes will help you ensure the highest quality welding possible.