What types of gases are used when welding?
Welding requires the use of a variety of gases. Some welding gases can be used purely, while others are mixed with one or more gases to create a combination. Welding gases vary in cost and application.
If you’re interested in learning more about the types of gases used in the many welding processes, keep reading! We’re going to cover when to use each type of welding gas, in both pure and mixed forms. Then we’ll cover the benefits of each type of gas. Finally, we’ll discuss costs and expiration.
Knowing what type of gas to use in each welding technique is half the learning process. The more you know about the types of welding gas you’re using, the better welder you’ll become!
A Little About Welding
The 2 most widely used types of welding techniques are MIG and TIG welding. MIG stands for Metal Inert Gas and TIG stands for Tungsten Inert Gas. These processes are so named because MIG welding uses a wire to feed the bead, while TIG welding uses a tungsten electrode to heat the filler metal. Depending on what type of welding process you’re using and what metal you’re working with, you’ll want to use a specific gas or gases.
Both MIG and TIG use what are known as “shielding gases.” The process of welding joins 2 metals together, but such a (perfect) union is not always the easiest to accomplish. The 2 metals are not like peanut butter and jelly, where they want to mesh cohesively. Instead, the metals are—as you might imagine—hard and smooth. This complicates the welding process.
The shielding gases used in MIG and TIG welding create a better environment for the 2 metals to join. The gases prevent oxygen and water from getting into the work area that is being welded. Oxygen and water are undesirable in this case because they promote oxidization, which weakens any bonds a welder succeeds in forming. Any welder knows that a strong joint is a solid joint.
The gases we’ll be discussing are all categorized as shielding gases. Each gas is either semi-inert or inert. Now that you know a bit more about what welding gases accomplish, let’s take a closer look at each type and how they’re used.
Welding Gases and Their Uses
Argon is the first welding gas we’ll discuss. This inert gas helps break down oxides in the metals being welded. When welding with argon, the arc is very stable. This in turn gives the welder better control over the weld pool.
Welding with carbon dioxide can be tricky because it makes the arc unstable. However, you can get deeper penetration when welding with carbon dioxide, so there are trade-offs. Helium also makes the arc unstable but increases penetration. Welding with helium allows you to supply more heat to the metals you’re working with, so it may be good in some situations.
Hydrogen is a good welding gas to work with. Not only does it stabilize the arc, but it also creates a better surface for the bead to happen. Typically, you can weld faster when using hydrogen because the arc gets to a higher temperature.
Nitrogen is an interesting gas to weld with. It is often used to purge stainless steel tube while welding but can create a wandering arc. This might be a difficult gas to work with for beginner welders.
You might think it odd that oxygen is used as a welding gas, but it is in fact often mixed with other gases in order to weld with. Adding oxygen to your gas mix will stabilize the welding arc and improve weld penetration.
Keep reading to find out more about different types of welding gas combinations and their corresponding applications.
Common Welding Gas Combinations
To understand the various mixes of welding gas, you must first consider the material(s) you’re welding together. Different types of metal react to the various gases, in pure form and in combination. This means you’ll want to know what gases are good for what applications to insure the best welds.
Here is a list of the common mixes of gases used in various types of welding situations:
- Carbon steel: To increase weld penetration when working with carbon steel, mix together argon and carbon dioxide. Usually a combination of 75% argon and 25% CO2 will suffice.
- Nickel and Copper: Blending argon and helium together in varying degrees works best when welding these types of metals.
- Aluminum: Welding aluminum can be tricky because it wicks away heat so well. Most aluminum pieces can be welded using just argon, but for components ½-inch or thicker, add a bit of helium to increase penetration.
- Stainless Steel: In addition to argon and carbon dioxide, add a dash of helium to successfully weld stainless steel. Work with 90% argon, about 7.5% of helium, and 2.5% carbon dioxide for this application.
There are lengthy, scientific explanations for the reasons why you’d want to use each type of combination above. However, understanding the thought process behind it all begins with knowing what a good weld looks like and in what environment it thrives. If you know what you want to achieve, you can begin to work towards it.
With that said, let’s talk about what an ideal weld needs to be successful.
Welding is much more than just joining 2 different pieces of metal. There are entire processes that come before the welding even begins. To understand why you should weld with certain gases, let’s first consider what the “perfect” weld looks like. Or, at least, how it might look if it existed.
The environment in which you weld is key to the success or failure you experience. First, as in many cases, your work space should be as clean as possible. This not only applies to the surface you’re working on, but the metals themselves. Because welding gases burn to create heat, they will engulf any contaminants present. You can theoretically burn off debris to clean the surface but it’s always better to use processes that don’t burn the gas you use to weld with.
Achieving proper heat penetration and gas flow is half of the battle of welding. Both materials you’re working with should theoretically be the same temperature (in the spots you’re welding) if you’re going to be successful. This ensures they bond and cool down at a similar rate. However, this is not always the easiest to achieve.
To increase your effectiveness when welding, use specific gases for certain applications. We’ve talked about a few combinations previously, and when to implement them for best results, but understanding the concept behind the use of each gas is just as important as knowing what combo to use and when.
For example, say you’re welding together 2 metals. You know what kind of metal each piece is, but you’re unsure about what gases you should use. Perhaps you’re working with metals that require a mix of gases. How do you know how much of each gas to use? Do you know why you’re using a combination in the first place?
Benefits of Various Welding Gases
We talked about some of the common gas mixes out there in the welding world, but what makes one combination good and another bad? To understand that, let’s take a look at the benefits of each type of gas.
- Argon = According to Lincoln Electric, argon is the least likely to react with the weld metal. When added to a bit of carbon dioxide, argon reduces weld spatter and promotes a flatter bead profile.
- Carbon dioxide = Use this gas when you are welding thick materials together.
- Helium = You can also use helium to weld together thicker materials. Helium creates a hotter arc, which improves welding speed and productivity.
- Hydrogen = There’s no need to use flux when welding with hydrogen. This gas also allows you to reach higher temperatures, which can speed up the welding process.
- Nitrogen = Much like argon, nitrogen is in great abundance and therefore cheap. It is also nonreactive and weighs less than argon.
- Oxygen = Be careful how you use oxygen. When implemented in the right circumstances, it can improve fluidity, penetration, and welding arc stability. However, it does still oxidize the metals you’re working with, so use oxygen wisely.
Welding Gas Costs
Beyond buying the necessary filler for your welding, gas will be your next and most likely largest expense. Welding gases can vary greatly in cost. Some gases are incredibly cheap while others will weigh heavier upon your funds.
Again, it’s important to know what types of gas you’ll need before you begin welding. Figure out what metals you’re working with and plan out your welding beforehand. Do you need to use a pure gas, or a mixture? Keep in mind that the better welds you’re able to achieve, the stronger your joints will be.
Helium is going to be the most expensive welding gas. Argon is not far behind, but it’s not as much of a drain on your savings as helium is. Hydrogen, nitrogen, CO2, and oxygen are all going to be readily available at most gas companies and at reasonable rates.
Best welding practices start with knowing what types of gas you need, but it’s also a good idea to call around and get a few quotes as well. Inquire with local shops about their rates and what gases they stock. How do their filling procedures work? What types of programs do they offer if you’re going to be using gas frequently?
The more you know about welding gases, the more informed you can be in deciding what types to purchase and who to purchase from. Speaking of which, keep reading! We’ve got one more important safety topic you should know before you step out to buy some welding gas. Because many of these gases aren’t stable, like the air we breathe, it takes a certain amount of respect in order to handle them responsibly.
When Does Welding Gas Expire?
The truth of the matter is that welding gases do not necessarily have an expiration date. The containers, however, do expire. The gases will and do exist naturally in the world. With some exceptions, they are able to flow and change as needed. But when you place these gases under slight pressure inside of a container, safety enters into the equation.
Most gas cylinders are manufactured to specifications set in place to ensure safe use. While many cylinders can theoretically be pressurized to much higher ratings than the given value, you should visualize this as a safe practice and barrier against failure. Not as a challenge to push the limits of the container before you.
You see, manufacturers produce gas cylinders and stamp them with a date. This denotes the last test date. Most date stamps are close to the gauge and specify a month and a year.
Typically, when you go to purchase a welding gas cylinder, the gas company will already have performed testing on that particular container. First-time gas purchasers will most likely want to buy the container—and of course the gas inside—and then simply bring it back to the same company for a refill later on. If you’re not sure what the service interval is for your cylinder, check with the company you purchased or leased it from. They will most likely perform the testing themselves.
What Will You Weld?
Have you learned a lot more about welding gases after reading this article? We hope so! There are a ton of great projects you can make with welding. Just remember to stay safe and be smart about how you weld and with what gases. It’s always better to ask questions and be sure than to guess and regret it later. Thanks for reading and have fun welding!