Welding gas is an important component of MIG and TIG welding. While you can attempt to MIG weld without it, the quality of the resulting weld is just not as good. And in the case of TIG welding, gasless welding is not at all possible. When it comes to sizes, there are many different options, although the most common welding gas bottle and cylinder sizes are the 40, 80 & 125 cu/ft ones. Below, we’ll share some of the best options available to you.
Unbeknownst to many, choosing what welding gas to use is not limited to selecting which one is suitable for your chosen workpiece. You also need to consider other aspects, such as the right settings when using for MIG and TIG welding and the cylinder sizes suitable for your workshop.
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At a loss about all these? You don’t have to. You just need to keep reading to find out more, as well as learn some tips that can prove handy for all your welding projects. We will walk you through all the different aspects that are important to you, and then we will be sure to leave you knowing a lot more about the topic as you are done reading this article.
It’s important to know that there are different kinds of gases, and different ways for each to be used. Each of the different gases has its own set of functions that it is trying to achieve.
Types of Welding Gas
When we talk about gases in welding, most people would immediately think of the shielding gas. What they don’t realize is that there are actually different types of welding gases used. There are also gases used to clean the welds formed or protect the materials after welding.
Some metals or filler rods require preheating before welding to ensure a quality weld or brazing. For this purpose, you need to use heating gas. This type of gas is typically a mix of fuel gas with some oxygen added and when it is lit up, it gets warm enough to heat, but not melt, the materials. Read on in order to learn more about the individual types.
To prevent the contamination of the molten pool when MIG or TIG welding, which results in an ugly weld, you need to use a shielding gas. This type of gas is important because it not only affects the appearance of the weld but also the bead shape and penetration, alloy content, fumes produced, and many others.
Shielding gases are often inert gases and can either be pure, which is made up of a single type of gas, or a mix of different gases. The pure gases are argon, carbon dioxide, and helium, while the mixtures used as shielding gases can include different combinations of pure gases or adding oxygen, nitrogen, or hydrogen to them.
Among all the pure gases, argon is the most widely used shielding gas because it is inert and will not cause a reaction to the metals being welded. Because of this, it is suitable for aluminum welding, as well as for other metals that are refractory or reactive. You can use this gas with all types of materials in TIG welding, while its use in MIG welding is limited to nonferrous materials.
Argon also causes a low heat transfer because both its ionization potential and thermal conductivity are low, creating the deep and narrow penetration it is known for. Not only that, but you also get a very stable arc that allows you to have better control over the weld pool. Also, argon aids in the breaking down of any oxides present in the workpiece.
In contrast, helium is known for having high ionization potential and thermal conductivity that results in a deep but wider weld and increased heat. Unfortunately, it also makes starting the arc much more difficult, especially if you do not use the correct settings of your MIG or TIG welder. This gas is not commonly used in MIG welding and is only suitable for nonferrous metals when using it for TIG welding.
Carbon dioxide is normally only used for MIG welding, as well as the highly-similar flux core welding, because it has complex interactions with different metals. With this gas, you get a balanced weld ratio in terms of depth and width due to its wide penetration and high heat. This increased heat is also because of its low thermal conductivity and ionization potential.
Using different shielding gas mixtures is a common practice. In fact, these mixtures even work better with certain metals compared to using pure gases. Found below are the different metals and recommended mixtures of shielding gases to be used when welding:
- Carbon steel – argon and carbon dioxide, argon and oxygen, argon, carbon dioxide, and oxygen
- Stainless steel – argon and carbon dioxide, argon, carbon dioxide, and helium (aka tri-mix), nitrogen and hydrogen (only for austenitic stainless steel)
- Aluminum – argon and helium, tri-mix
- Light gauge steel – argon and oxygen
- Nickel – argon and helium
- Copper – argon and helium
A common issue is that welders take strides to ensure a neat weld on the surface but neglect the underside of the weld. Because of this, the underside looks different and can even be contaminated because it is unprotected by any shielding gas.
To address all these, doing a back purge is necessary for a clean weld on both the surface and its underside. When back purging, a purging gas that acts like a shielding gas is used for the underside. This process is usually done when welding stainless steel, as well as nickel and titanium alloys.
Carbon dioxide and nitrogen are often used as purging gases, but you can also use other inert gases like helium and argon.
In instances where you need to ensure that your finished weld must be completely flaw-free, a shielding gas may not be enough to prevent contamination. As the weld cools, it can still be stained or damaged by any contaminants present in the atmosphere. Using a blanketing gas, often nitrogen, will protect your workpiece from these contaminants.
Shielding gases are the welding gases used most often, but it is also important to familiarize yourself with the other types you can use for your projects.
Welding Gas Bottle, Tank & Cylinder Sizes
A welding gas is typically not flammable but it still poses some health risks, that is why you need to choose the right cylinder size for your workshop. Not only that, but it will also provide convenience for you because you don’t have to keep getting a new one when you run out of gas while welding.
High-pressure gases, namely oxygen, helium, nitrogen, hydrogen, and carbon dioxide, use cylinders with uniform sizes. A high-pressure gas cylinder, also called a bottle or tank, typically has volumes ranging from 20 to 300 cubic feet. Bottle sizes are indicated either by their volume or represented by letters, such as:
- R = 20 standard cubic foot or scf
- V = 40 scf
- Q = 80 scf
- D = 125 scf
- S = 150 scf
- K = 200 scf
- T = 300 scf
Note that the welding gas bottle sizes above apply for those encased in steel cylinders. There are also aluminum cylinders available, but they have much more limited sizes.
Low-pressure gases, on the other hand, have more varied sizes.
Gas Tanks for Welding
When it comes to welding, argon is arguably considered as the most important gas. Different welding types use different amounts of argon, as well as other gases, so you need to know which gas tanks to use for your welding project.
The problem lies in the fact that, with the exception of high-pressure gas bottles, many of the gas tanks used in welding come in different sizes depending on the manufacturer. This is purposely done by manufacturers so that they can easily identify which tanks are theirs.
Despite this, they also make gas tanks in sizes that can be considered common to different manufacturers. Argon, for example, has the following common sizes that are represented either by a letter or number:
- R or 20 = 21 cubic feet
- RR or 40 = 44 cubic feet
- Q1 or 60 = 65 cubic feet
- Q or 80 = 83 cubic feet
- S or 125 = 125 cubic feet
- S or 150 = 155 cubic feet
- K or 250 = 251 cubic feet
- T or 330 = 335 cubic feet
Note that the S-sized gas tanks have two types available, that is why it is important for you to check the actual volume when purchasing this type of tank. And in most cases, the smallest-sized gas tank allows you to weld continuously for an average of 1 hour to 1 hour and a half.
Gas Settings for MIG and TIG Welding
Aside from choosing which welding gas to use and the right bottle size you need, you also need to determine the right gas settings for MIG and TIG welding.
Using welding gases is not as simple as letting them flow freely as you weld. You need to make sure that just the right amount is being released because this will also affect weld quality. Both MIG and TIG welding have uniform gas settings regardless of the type of shielding gas.
When it comes to MIG welding, the flow rate typically ranges from 25 to 30 cubic foot hours (CFH) and its matching pressure should be between 3 to 7 psi. Most welders consider 20 CFH as an ideal flow rate, since setting it higher increases spattering and also makes the weld porous. Note that bigger nozzle diameters, as well as drafty conditions, will require higher gas flows.
The gas flow rate of TIG welding, on the other hand, is typically lower than that of MIG welding and ranges from 15 to 25 CFH on average. However, it can also go up to 50 CFH if you use larger cup sizes. If your flow rate is between 35 to 50 CFH, the pressure should be between 20 to 30 psi to match it. But if you have a lower flow rate, you also need to lower the psi.
MIG and TIG welding both require the flow rate and pressure to be directly proportional. That is, the higher the flow rate, the higher the required pressure. They only differ in the actual numbers.
Gas Welding Tips
These different gases are extremely helpful when welding, but using them is not as straightforward as some would think. Whether it’s your first time to use gas when welding or you have already tried it but have yet to get satisfactory results, these tips are sure to help you out.
- Use a gas lens if you want the flow of shielding gas to be evenly distributed and lessen weld defects caused by contamination
- If you want a laminar flow, opt for a converging nozzle with the longest length and largest diameter suitable for your welding project
- To get the best results, you should do a pre-flow and post-flow of the shielding gas
- Don’t ignore any gas leaks. Not only will it contaminate your work, but you also end up wasting gas and money because of it
- Back purging is the best way to prevent sugaring or oxidation on the underside of your workpiece
- For aluminum welding, lessen the gas if you are welding on A/C
- When working on sheet metal, opt for a shielding gas with a higher argon content for less spatter
- Use tri-mix gas consisting of 90% helium, 8% argon, and 2% carbon dioxide when MIG welding 304 and 316L stainless steel
- Test if your gas flow is appropriate by placing your hand around 3 inches from the nozzle tip and allow the gas to flow. If you feel the gas at this distance, it means you have an adequate gas flow that will prevent a porous weld
- Refer to manufacturer recommendations in terms of which shielding gas to use with your welder and workpiece. Your shielding gas should also match your welding wire.
- Ensure that the shielding gas flowing out sufficiently protects the molten pool to reduce spatter
More is not necessarily good in terms of using welding gases. For both MIG and TIG welding, you need to use the right amount of gas for your welding projects. If you use more than what is necessary, it will be easier for your workpiece to be contaminated.
Did this article better help you understand what you came here to learn, or did you think there aspects related to welding gases that you would have liked for us to include? We love receiving input from our users, and often include some of their feedback into the articles. If you are interested in continuing to read, we have a couple of interesting articles on plasma cutters, and there is one on the best engine driven welders, too. Or perhaps your interest more so include learning how to actually use a plasma cutter, which we can also help you learn.
Here at Atlantic Aspiration, we’re on a mission to transform the built world, and help create more transparency, as well as educational resources for those people wishing to become better builders and creators, why we are continuously adding topics and articles. If you have an article in mind, or if you might be interested in providing a welding related article on something you are really passionate about, we invite you to reach out to our team.
FAQ section on welding gases
If you don’t have the time to read the entire section above on weldig gas, we encourage you to read this section that will make it possible for you to get a lot of the same information, however it has been compressed here. We have also given it various different titles, making it easier for you to find the information that you are looking for. The above section does provide a more in depth review of all your various options, so you may want to take a closer look at that if you haven’t already.
If you read the above section, but you still feel like you have unanswered questions, there is a chance that reading this part may satisfy your curiosity.
Should you weld without shielding gas, or perhaps, what happens if you choose to do so?
If you don’t use the adequate amount and type of gas, you will find your welds being porous and weak, why it is imperative that you understand the use of this material for your work. Flux-clad or flux-core arc welding can be used without the use of shield gas, but it is otherwise imperative that you use it. As you don’t want to contaminate your weld pool as you are working on it, you will want this matearial to do its job and protect the work that you are doing!
Are all gases inert, and if not which ones are?
The two gases that are in fact considered to be inert are helium and argon. There are also two gases that are SEM-inert, and those include carbon dioxide and nitrogen.
Can you use any type of gas when you are welding?
The type of gas that you are using will depend on the type of welding outcome you are trying to achieve. In welding, there are only some gases that are used that include compressed air, propylene, propane, acetylene, hydron, nitrogen, helium, oxygen, carbon dioxie and argon.
If you are interested in learning more, we recommend you to read the article on oxy acetylene settings when you are using a cutting torch, which we have written an extensive article on as well.
How can I make sure that I don’t end up spending significant amounts of money on gas alone? And what is the most common type of gas used?
We fully understand if you are concerned that you’ll be raking up a huge bill on gas, and we do have a recommendation when it comes to that! The easiest way to keep your gas cost down when you are welding is by using a mixture of argon and carbon dioixide, which will both ensure that you get good results, but also ensure that you aren’t spending massive amounts of money on your welding projects. If you are doing a lot of welding, going with this gas combination, you can really save a lot of money! Because of ts price tag, the argon and carbon monoxide gas mixture is also the most common option that welders choose!
What is a shielding gas?
A shielding gas helps maintain the quality of your welding by keeping the weld from becoming contaminated with the absorption of various things like hydrogen and oxygen, which can be found anywhere in the atmosphere.
Argon and carbon dioxide are the ones that are most commonly used to make sure that your weld does not become contaminated.
Best gas for MIG welding – which one should I go with?
For metal arc welding, your best bet is argon as it can be used no matter the grade that you are going for! You should know that it can be mixed with other types of gases depending on the result that someone is trying to achieve.
All the good stuff that we have to offer on here
There is no denying that we are one of the new players in the industry when it comes to welding equipment, but we come from a background of wanting to change the industry! We’re not just trying to become your place that you go to when you want to research welding gas. Rather, we are trying to become a more encompasing resource that not just offers various guides but also helps either experienced welders, and aspiring ones find the equipment that is right for them.
There’s no denying that if you don’t know what you are doing, it is very easy to end up spending way too much money on equipment. On the other hand, it’s also easy for you to spend too little money and effectively end up with a piece of welding equipment that just doesn’t do what it is that you want it to do.
Our goal here at Atlantic Aspiration is not just to sell you a piece of machinery. We want to understand what your welding goals are so that we can match you with the piece of equipment that you will come to love, even long after you have forgotten that you read this article!
We invite you to read al the various sections, or simply to explore the section that you have the biggest interest in.