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 | Plant Engineering  | Plant Engineering

Reduce weld fume exposure by choosing the right option

Protecting employees against weld fumes is critical to providing a safe working environment. Choosing the right welding solution involves many key factors including the welding process, the type of fumes produced, and the OSHA standards relevant to the manufacturing process.

10/12/2017


Manufacturing operations understand that protecting employees against weld fumes is critical to providing a safe working environment—and it’s also an issue of staying compliant with regulations. 

What many manufacturers may not realize is that some weld fume management solutions also can help significantly improve productivity—and the bottom line—so it’s important to consider which option can help save the most time and money in your operation. Fume extraction MIG guns are a source capture option that use a fume chamber above the nozzle connected to a high vacuum system to capture welding fumes very close to the source—before they reach the operator. Images: Courtesy Miller Electric Mfg. Co.

In the United States, OSHA is the first line of worker protection. Another great resource is the American Conference of Governmental Industrial Hygienists (ACGIH), a member-based organization that develops recommendations at a deeper level of assistance in the control of occupational health hazards.

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When choosing a weld fume management solution, consider these key factors: the welding process used or being implemented; the type of filler metal and consumables used; and the condition of all materials in the upstream process. It’s important to consider all steps involved in the welding operation before making any changes or implementing new solutions.  

Not all welding processes or filler metals are the same; some produce more weld fumes than others. To ensure success with the chosen solution, you must first know what types of weld fumes are being produced. 

Becoming familiar with OSHA’s Hierarchy of Controls is also key. The hierarchy outlines the steps employers can take to comply with environmental regulations and improve workplace safety. Before trying any steps in the hierarchy, first conduct air sampling within the facility with the help of a certified industrial hygienist or safety professional. Air sampling identifies the type and concentration of contaminants present in the facility.

Step 1: Process modification or substitution 

The parts and types of materials in the upstream process can vary greatly—as can the condition of those parts. Always consider what can be done upstream to minimize or eliminate the source of weld fumes later. Sourcing clean materials or cleaning parts before the welding process can help.Overhead capture hoods are another source capture option. Overhead hoods, which vary in size, are placed above the work area and connect to ductwork and a larger centralized fume extraction system.

A change to the welding process, consumables, or filler metal also can help reduce the amount and type of weld fumes produced. Options include switching from stick welding to MIG, or from self-shielding wire to solid wire to reduce fume generation.  Any time you can improve the weld process by reducing spatter and stabilizing the weld puddle, overall fume generation is reduced. Spatter and fume generation also can be reduced by using higher end processes that offer advanced puddle control and stability in combination with mixed shielding gases that provide higher argon content. 

Substituting alternate materials or filler metal consumables is another approach to consider.  Filler metal products with low manganese content can reduce manganese fume emissions. When combined with processes such as advanced pulsed MIG welding, this may result in a 60% reduction of manganese in fumes compared to standard filler metal fume emissions.  

While selecting the right welding process or filler metal can reduce weld fumes, these modifications may require recertification of welding procedures or additional training and testing costs. 

Step 2: Engineering controls 

If fume can’t be eliminated or significantly reduced through process modifications, the next step is to consider implementing engineering controls. These include process enclosure, general ventilation or source capture, and may require a physical change to the workspace.

General (ambient) ventilation includes using the building’s HVAC system or high-powered fans to move large quantities of air to dilute weld fumes with fresh air on a predetermined air exchange rate. While it may be seen as an easier option to implement than source capture, this solution circulates air within the space rather than capturing fumes. Ambient solutions do have their place, such as when operators weld on large workpieces, making it impractical to move a source capture arm each time they change position. In this case, a ventilation system should be paired with the proper personal protective equipment (PPE).

Process enclosure is another option in some applications, such as robotic welding. This solution uses an enclosure to create a barrier between the process and the operator, so all the fumes are contained within the weld cell. Not all robotic welding applications eliminate exposure during part changes, however, and the operator must wear proper PPE if air sampling determines it’s necessary. This option can eliminate the issue of weld fumes for other workers outside of the cell. 

Source capture through fume extraction is the best solution when considering the scale of good, better, best in engineering controls. Capturing fume at the source before it reaches the worker’s breathing zone should be the goal in every facility. Source capture options include fume extraction MIG guns, hoods and arms, which are both available in portable and stationary models. 

Some source capture solutions are difficult to position over large weldments or other obstructions within the weld cell or fixturing, which can be a disadvantage. In addition, welding operators working on large weldments may not want to frequently reposition a source capture arm as needed. 

In these cases, a fume extraction MIG gun may be the answer. These MIG guns use a fume chamber above the nozzle connected to a high vacuum system to capture welding fumes very close to the source—before they reach the operator. Keep in mind that fume extraction MIG guns are best suited for flat, in-position welding.  

Typically, extraction systems with standard source capture fume arms capture weld fumes at a distance equal to the hood’s diameter over the weldment. When considering source capture options, look for one with the latest technology that creates a much larger capture area and minimizes arm interactions. This reduces or eliminates the number of times the operator must adjust or move the arm—saving time and improving productivity. 

Overhead capture hoods are another option. Overhead hoods can be as small as 4 ft. by 4 ft. or as large as 16 ft. by 16 ft. They are placed above the work area and connect to ductwork and a larger centralized fume extraction system. Hoods with a low profile are designed to minimize the space they require. Hoods typically can cover more area for fume capture than arms. 

Step 3: Work practice (administrative) controls

The next step is to implement work practice controls, which do not remove hazards but instead limit or prevent an operator’s exposure to weld fumes by modifying behavior or the work environment. This step often involves proper operator training or modification of jigs and fixtures to allow for more ergonomic body positions in relation to the weldment and work habits to limit fume exposure. Even small adjustments can reduce exposure rates significantly and greatly improve productivity by helping operators be more efficient. 

In following work practice controls, welding operators should use basic best practices, including keeping their heads out of the weld plume; changing body position to take advantage of airflows moving from back to front; and making sure any air movement in the work area pushes fume away from the breathing zone.

Choose welding helmets that offer a larger, clear view of the weld puddle. These allow operators to stand in a better position to keep their heads out of the weld plume—while still having a clear view of their work. Combined with regular vision testing, better helmets provide welders with more options for positioning—resulting in higher-quality work.

Step 4: PPE

The final step includes implementing respiratory protection such as disposable masks, half masks, powered air purifying respirators (PAPRs) or supplied air respirators (SARs). In some applications, PPE may be the only viable solution that reduces weld fume exposure below required levels. However, there are additional steps and expenses necessary with this solution, including medical evaluations, fit tests, training, and filter replacements. 

Respirators should be used if engineering controls are not feasible or do not reduce fume exposure levels enough, or during maintenance or emergency situations. Whenever respirator use is either mandatory or voluntary, companies must establish and maintain a written respiratory protection program as stated by OSHA 29 CFR 1910.134. 

Each type of respirator is given an assigned protection factor (APF), which is the level of protection it will provide when used properly in conjunction with a written respiratory protection program. Companies must consider the respirator’s APF, air-sampling results within the facility, and OSHA’s Permissible Exposure Limits (PELs) for those contaminants to determine which respirator is suitable. To get the most out of the respiratory protection, ensure each employee has selected a respirator that provides a comfortable fit and does not negatively impact productivity.  

There is no one-size-fits-all solution to minimize fume exposure in manufacturing welding applications. When determining the right solution for the application, evaluate various products, get feedback during the process, and encourage welding operator involvement to enhance buy-in. 

Remember, proper training is also key for successful implementation of fume management controls. And depending on the environmental factors and the goals of the operation, it may be necessary to implement multiple solutions from OSHA’s Hierarchy of Controls. 

Al Hilbert is a service manager for Miller Electric Mfg. Co.



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