In the past, stick welders didn’t know much about gases when it came to welding. This changed with the invention of MIG and TIG welding machines and the rise in their usage. Gas is now considered a common commodity in most welding workshops.
But how much is welding gas?
Purpose of Welding Gas
Gases are used in welding for several reasons, with the main purpose being shielding the arc from impurities in the air like dust or other gases. It is also used to keep the weld clean, as well as for heating metals.
There are two categories of welding gases: inert gas and reactive gas. Inert gases do not cause change, nor do they change themselves when they come in contact with other substances or temperatures, and remain the same throughout the welding process. These help weld metals without any unwanted weakening or distortion of the weld.
Reactive gases are the opposite, and as the name suggests, react according to the circumstances they are in – they create change, and change themselves as well. These can be useful by enhancing how the metal is fused through positive changes.
The main purpose of using gas in welding is for shielding. When the air gets into the arc in the middle of welding, it causes air bubbles within the molten metal, which ruins the appearance of the weld and weakens it. MIG or TIG welding becomes impossible without a shielding gas unless the filler metal being used is flux-cored or coated, which does the same job of keeping impurities out of the weld, albeit in a different way.
Shielding gases are most commonly inert. By being inert, they remain stable during the extreme heat and pressure conditions during welding, which makes them the ideal choice for such a job. They are also able to nurture the weld in different ways depending on what gas is being used, such as providing more penetration, more fluidity, etc.
Gases Used in Welding
There are a few main gases used in the welding process.
Argon is an inert gas, so it does not react with other substances and is one of the most abundant gases on earth. In welding, it is used as a shielding gas to keep the air out of the welding arc. It is also used in the primary welding stages, as well as in purging. Most often, however, it is used as a shielding gas and is often used in shielding mixtures during MIG welding.
Carbon dioxide is another abundant gas found on earth. It is also used as a shielding gas, and because it is created from organic matter, it is not expensive, though it does not produce the same quality welds that argon does. Carbon dioxide is commonly used in mixtures rather than its pure form for this reason. It is also used in flux core welding, MIG welding, and plasma shielding.
Oxygen is often considered a friendly, passive gas, but, in reality, it is one of the most reactive gases in the world. It is often used in welding mixed in small amounts of shielding gases to add fluidity to the molten weld and make the process faster. It amplifies heat during gas welding and is used to cut metals in a process called oxy-cutting. When mixed with acetylene, it creates the only flame that has a temperature high enough to weld steel.
Nitrogen is the most abundantly found gas in the atmosphere and is essential for all living organisms. It is used as a shielding gas, and when mixed with other shielding gases, it can also be used for other more specific applications. It increases alloys’ mechanical properties and deepens penetration while also stabilizing the arc.
Hydrogen is used as a fuel that burns without emissions and found abundantly on earth. It is used as a shielding gas in mixture with other shielding gases but in very small amounts to avoid danger. It can increase penetration and makes a cleaner weld than other gases.
How Much Welding Gas Do You Need?
When you’re new to welding, you might not have an idea of how much welding you have to do for a certain project, let alone how much gas you need. You would want to have an idea of how long a welding gas bottle would last you before you decide which size you want to choose.
Welding Gas Bottle Sizes
In many cases, homeowners and hobby welders, who do not have to weld a lot of material at once and mostly have to do small jobs, will choose gas cylinders of 40, 80, or 125 cubic feet (cf) volume. Larger cylinders allow for a greater welding time, since they have more gas, while the smaller ones are easier to transport. Larger cylinders with higher volumes are usually available but are usually leased to customers who demand higher volumes, such as for industrial work.
How Long Will Welding Gas Last?
The amount of time your welding gas cylinder lasts depends on your regulator’s flow rate, which you have to set yourself. Depending on the work environment, this is probably going to be somewhere between 10 to 40 cfh (cubic feet per hour). For windy areas, you need a higher flow rate to maintain the shielding gas around the weld and protect it from air bubbles, etc. Even the smallest breeze can cause problems, so if you are working in an area where there is a high chance that a breeze can enter, such as your garage if the door is open, you might need to set your regulator at a higher flow rate.
Therefore, gas welding time for cylinders is calculated by dividing the volume of the cylinder by the flow rate. This will give you the number of hours you can use your gas cylinder while welding.
Depending on the welding machine, you may also lose gas faster than with other machines. For example, if the machine dispenses gas all the time, your gas will not last as long as if it were to dispense only while welding.
Finding Out How Much Gas Is Left
Of course, you may want to know how much gas is left in your cylinder at any point, if you want to keep welding. A full welding gas cylinder will have a pressure gauge reading at the cylinder’s working pressure, which would be provided to you. Unless there is a leak or drastic temperature change, such as entering a sudden cold or hot environment, you can expect that the pressure of the cylinder will respond linearly to the remaining gas volume.
For example, if your full cylinder had a working pressure at 1000 psi, then a later reading of 1000 psi would mean that your cylinder is approximately half full. Some pressure gauges have a greater level of accuracy than others, which can cause some concern among new welders, but you will get a feel for accuracy with practice. As long as the regulator maintains a set flow while the trigger is pulled, you can continue with your welding and be assured that your shielding gas is protecting your weld.
Sometimes, the gauge may hold steady and fall suddenly. This is because of a hang-up because of the slow gas discharge and is not a cause for concern.
How Much Does Welding Gas Cost?
Depending on the size of the cylinder and what gas you are buying, the cost of the gas may vary greatly, leading up to $350 per cylinder. Argon gas is generally more expensive than others because of the difficulty with which it is collected.
You can also choose to get your gas cylinder refilled instead of buying a new one. This process is much more economical than buying new cylinders. If you purchase a larger cylinder with a higher volume once, refilling it will be more economical and cost-efficient than refilling many smaller cylinders.
How much gas does a MIG welder use?
For average-sized MIG welds, you’d need about 25 to 30 cfh of gas, but if the metal is thicker, you’d need to weld with more gas to complete the weld and make it look aesthetically pleasing.
How long does an argon gas tank last?
An average-sized tank of argon gas for industries will last about 10 hours at a 20-25 cfh flow rate. Household tanks, on the other hand, will last approximately 3 to 4 hours.
Can argon gas kill you?
While argon is an inert and non-poisonous gas, it is odorless, colorless, and tasteless, which means that if too much of it surrounds you, you may not get the amount of oxygen you need and can result in asphyxiation.