Gases for GMAW / MAG Welding of Carbon Steels

Tackle Welding Fume Emissions at the Source

Take occupational health and safety to the next level by combining exposure controls with our PREVENTION LINE of gases for reduced fume formation at the source

Enhancing OSH Through Substitution Measures in the Hierarchy of Controls

The many advantages of gas-shielded arc welding processes such as gas metal arc welding (GMAW) or metal active gas (MAG) welding are well-appreciated in the metal fabrication industries. However, the welding fumes generated by these processes are considered hazardous from an occupational safety and health (OSH) perspective. Welding fumes are a complex mixture of particles, with sizes ranging from respirable to inhalable scale. The chemical composition of the fume particles is mainly determined by the metal alloy used in the filler (wire) electrode, since usually over 90% of fume emissions originate from overheating and vaporization of the solid filler in the GMAW / MAG welding arc. While these metal vapors are essential for arc stability, some of them can leave the arc zone and condense, forming welding fume particles.

When GMAW / MAG welding is used, measures need to be implemented to control the hazardous welding fume generated. The avoidance or minimization of human exposure to welding fumes and compliance with local regulations is obviously a high priority. Beyond the regulatory aspect, investments into more effective welding fume prevention can increase the attractiveness of welding companies. In the ongoing competition for qualified welders, a better working environment attracts and safeguards top welding specialists.

The “Hierarchy of Controls”, known as the S.T.O.P. principle in some regions, as illustrated below is a structured OSH methodology guiding companies on how to protect welders against exposure. It ranks control measures based on their general effectiveness, cascading down from elimination of the hazard as the most effective measure at the top. OSH regulations recommend that companies check all measures for applicability, starting from the top of the hierarchy, moving downwards, and combining measures for the best possible reduction of exposure.

As the complete elimination of arc welding is rarely an option in metal fabrication, we focus on the remaining four levels of control measures:

Substitution: Use a less-emissive GMAW process, optimizing the welding gas composition, arc parameters and/or filler metallurgy accordingly
Technical systems: Capture the fumes, isolate workplaces or ventilate accordingly
Organizational: Educate personnel, change behaviors and optimize workplaces
Personal protective equipment (PPE): Use powered air purifying respirators (PAPR), helmets, respiratory masks, etc.

All of these measures can contribute to occupational safety and health protection. As recommended by OSH regulations, many operators prefer to combine different measures for the best possible protection of workers. Our PREVENTION LINE of welding gases can reduce metal vapor formation directly at the source - in the arc. This has a knock-on benefit. If the fume emission rate (FER) has been successfully reduced directly at the source, downstream measures like fume extraction or PPE will work more effectively.

The Hierarchy of Controls is a regulatory Occupational Safety and Health (OSH) procedure implemented internationally, with national- or hazard-specific adaptations. The graphic above is proposed by Linde as an informative adaptation, particularly for gas-shielded metal arc welding processes like gas metal arc welding (GMAW), metal-cored arc welding (MCAW) and flux-cored arc welding (FCAW).

Innovative Approach: PREVENTION LINE Welding Gases as Substitution Measure to Reduce FER

We developed our PREVENTION LINE of welding gases specifically to reduce FER at the source, without compromising on weld productivity or quality. As part of this process, we conducted laboratory tests, applying the relevant industry standards to explore the benefits of gases with a higher argon share for GMAW welding of low- and mild-alloyed carbon steels.

Scientific progress in arc physics indicates that a higher carbon dioxide (CO2) content in the welding gas focuses the heat input at the melting tip of the wire, leading to localized overheating. In contrast, higher argon content in our specialized gas mixes can spread the arc heat input over a wider area of the melting wire, reducing localized overheating and the generation of metal vapors.

Measured Reduction in FER Using PREVENTION LINE Gases for GMAW of Mild-/Low-alloyed Steels

GMAW of carbon steel with spray arc at 10 m/min (394 ipm), WFS 1.2 mm solid wire G3Si1 (ER70S-6). Fume emission measurement according to ISO 15011-1. Only Linde gas products tested. Data source: Linde Technology Arc Welding Laboratory.

Wider Benefits of PREVENTION LINE Gases

Not only are substitution measures with our PREVENTION LINE of gases positioned towards the top of the OSH hierarchy, but the use of gases with a lower CO₂ content can offer a broad range of advantages compared with shielding gases with a higher CO₂ content:

OSH: Lower welding fume emission rates
Productivity: Less spatter and oxides, resulting in less post-processing effort
Quality: Deposited weld material shows better metallurgical properties with less alloying element burn-off
Sustainability: Less fugitive CO₂ emissions (Scope 1) released in the welding process

PREVENTION LINE Gases in Action

Video above illustrates the visible reduction in fume emission rate (FER) achievable using PREVENTION LINE gases for GMAW of mild-/low-alloyed steels, with the left image based on an industry-standard C25 gas and the right image based on CORGON^® 8/ MIGMIX GOLD^™

Useful Tips: Fine-tuning Gas, Filler and Equipment Settings when Working with the PREVENTION LINE

Our research focuses not only on the gas impact, but also on the interdependencies between all variables. Our experts explore ways of fine-tuning these variables to help you meet your productivity and quality goals. In the following, you will find some useful tips.

Optimizing both arc transfer mode and gas may increase the benefit

Check if spray arc can be substituted by pulsed arc or lower-energy arc types
At a set wire feed rate, the arc length will change if the gas composition changes
Adjust arc parameters, e.g. voltage
Modern synergic power sources use proprietary arc control software, which can react differently to a gas change
Check if your welding equipment already offers optimized parameters for Linde gases listed here
Weld quality control and documentation depend on the industry branch, applied standards and company procedures
Check your weld job specification for what needs to be re-evaluated when implementing a gas optimization

Video above illustrates the impact of PREVENTION LINE gases on the visible fume emission rate (FER) when using C18 gas in a spray arc and a PREVENTION LINE mix with a higher argon content in a pulse arc

Disclaimers

Disclaimer re. Test Results

All fume emission rate (FER) data was generated according to industry standards (e.g. ISO and AWS) and are provided for reference and comparison purposes only. FER is only one factor affecting workplace air quality. Your actual welding conditions, materials, processes and methods will also affect workplace air quality and the welder’s exposure levels. Users and employers have the sole responsibility for and control over workplace conditions, including the manner in which work is performed and the safety measures taken. Always read and follow all information on product labeling and safety data sheets when using Linde products. Safety data sheets for Linde products, including references to other important and helpful information specific to your location, can be found by visiting your local country website.

If you have any questions about reducing or controlling welding fumes, or complying with applicable standards in your workplace, you should consult with a qualified industrial health professional who can assess your unique circumstances and provide customized advice about the options available to you.

Disclaimer Of Warranties

Because every welding environment is different, Linde does not warrant that customer’s use of its products will duplicate the FER set out herein since this data was produced under laboratory conditions and in line with applicable industry standards. Linde expressly disclaims any and all warranties, aside from those (if any) Linde expressly makes in writing for a particular product sold to a particular customer. Linde expressly disclaims any and all implied warranties, including any implied warranty of merchantability or any warranty of fitness for any customer’s particular purpose.

More Information on

Supply Modes

Looking how you can benefit from our PREVENTION LINE?

Talk to one of our experts and see how you can improve OSH for welders working with carbon steels

Contact your Linde Representative