Welding a silver metal rack with MIG welding

What Gas Pressure to Use for MIG Welding

MIG, or metal inert gas welding, is a very versatile welding process. It is a favorite among welders who need to finely join together two large or thick pieces of metal without too noticeable a weld. The benefits of MIG welding are numerous.

It is a much faster process than other kinds of welding – plus, it’s easier to learn and, therefore, much cheaper in the long run. After all, you won’t need to pay laborers quite as much for MIG welding since it isn’t nearly as complicated as other welding processes.

However, despite all of the benefits MIG welding offers, there is still quite a lot to understand about the process. You’ll need to know about all the different components that will come up during the MIG welding process, including gas pressure, managing the gas flow rate, and how that flow rate might adjust based on what kinds of metal you’re working with.

While, in theory, MIG welding is pretty easy to understand, it gets a little more complicated once you’re actually working with materials. In this guide, we’ll be breaking down what goes into the MIG welding process – let’s get started!

Why the Gas in MIG Welding Matters

To understand why gas pressure matters in MIG welding, you’ll need to understand the role that gas plays in the process as a whole. As the process’s name might suggest, inert gas plays a significant part in ensuring the welding process goes smoothly.

When heating up and cooling down metal during welding, you must account for oxygen and other contaminants in the air. While you’ve likely never thought of oxygen, nitrogen, hydrogen, and helium as contaminants, the truth is that they can prove to be quite a bother to the integrity of any welding process.

When oxygen and other gasses come in contact with heated metal, it can cause various detrimental effects, including corrosion and weaker welds.

To circumvent these effects, metal inert gas welding creates a protective atmosphere around the welding site by pumping gas through the welding gun into the weld pool or the site where the metal is being joined.

This atmosphere replaces the normal air that would otherwise come in contact with the metal being heated, protecting said metal from the harmful effects of oxidation and coming in contact with other contaminating gasses.

By protecting the weld pool, the MIG welding gas ensures that no outside contaminants come in contact with the MIG wire being used. This wire is much thinner than you’d typically see in other welding. This is partially because it is not covered in a layer of flux, which acts as another protective covering that a welder could use.

So, How Does Gas Pressure Come Into Play?

Now that you know the crucial role that gas plays in the MIG welding process, we can talk about the role of gas pressure. The pressure applied to the MIG welding gas you’re pumping into the weld pool will directly impact the integrity of the weld and its resulting strength.

If gas pressure is applied incorrectly, not only can it directly affect the weld quality you’re going to end up with, but it could also lead to damaged equipment if the welding bead you end up with is too strong or weak.

Most MIG welding jobs require a gas pressure of between 3 and 8 PSI, but different metals require different pressures. You’ll need to make use of a gas regulator to gauge what your gas pressure is at accurately.

Copper colored MIG welding wire

How to Manage Gas Pressure During the Welding Process

So, how do you regulate gas pressure? Well, most MIG welders will come with a flow meter regulator that has two gauges attached to it. One flow gauge shows the gas pressure in PSI, and the other demonstrates the gas flow rate.

These gauges allow people to view and adjust the gas pressure using a gas valve. Using these gauges, you can reliably regulate the overall gas pressure throughout the MIG welding process, allowing you to get the weld you want every time.

There are two types of measurements that you are likely to see during the MIG welding process. These are cubic feet per hour, or CFH, and liters per minute, or LPM. Since one utilizes imperial measurements and the other uses the metric system, the measuring system you come across will largely depend on where you live and the type of welding equipment you get – or, to put it more succinctly, where that equipment was manufactured.

We recommend that you familiarize yourself with both measurement systems, as there’s no telling which one you will need for each welding application.

Adjusting Gas Pressure Based On Metals

As you might have guessed, due to the wideness of the range in gas pressure measurements, you are likely to see in your average MIG welding process that different metals require different pressures.

That means that if you’re getting involved with MIG welding, you will need to know which pressure is required by which kind of gas.

If that sounds complicated, let’s break it down a bit more. Not only do different kinds of gasses necessitate different pressures, but different metals will further impact the gas pressure you should be using.

Most MIG welders will come with a chart for you to utilize when working with new metals that you might not be familiar with, thankfully. Nobody would expect you to remember the exact pressure number needed when working with a particular copper alloy versus a nickel-based one.

Welder with thick protective gloves welding metal pipe together

Adjusting Gas Pressure Based on Gas

You'll come across three main types of gasses when you get involved with MIG welding: argon, helium, and 100% CO2. Each will require a different gas pressure and flow rate, especially when working with different kinds of metal. Working with 100% CO2, in particular, can be a cumbersome experience because there is a risk of freezing occurring during the use of 100%.

Excessively cold temperatures could harm your welding equipment and interfere with the welding process. Not only could it pose a risk to the ability of your electrode to break down effectively, but it might also cause your resulting weld to fail.

Argon is an inert gas widely utilized for many kinds of welding processes. Due to its stable nature – it is a noble gas, after all – it forms a protective atmosphere widely lauded for its ability to effectively block out gasses that could be an obstacle to the MIG welding process.

What Else Is There to Know About Gas Pressure in MIG Welding?

Knowing how gas pressure plays into the MIG welding process might sound like it would be incredibly complicated, but the truth is quite the opposite. Once you know how to read any given gas's pressure and flow rate, you can effectively regulate the gasses involved in your welding experiences.

You’ll also need to know how different gasses interact with various metals, but this comes with experience and the frequent consultation of charts imbued with that kind of information. We hope this guide proved helpful in your understanding of regulating gas pressure while MIG welding.

Back to blog