Breathing Easy: Top 10 Welding Fume Collection Considerations
Implementing effective welding fume control ensures employee health and compliance with regulatory standards.
- By Brian Richardson
- Mar 01, 2024
Have you ever visited a smoky, air-polluted welding shop? Or, worse yet, worked in one? Welding and cutting activities produce harmful fumes and particles from manual and robotic welding, arc gouging, plasma cutting and laser cutting. These fumes not only pollute the shops and lower indoor air quality, but they also endanger the health and safety of workers.
Reducing exposure to hazardous metalworking fumes, which consist of many different sizes of airborne dust particles, is most effectively achieved by incorporating dust collection systems equipped with high-efficiency primary cartridge-style filters. Certain types of particulates may even require secondary safety filters.
Here are ten important considerations to address when developing and executing a welding fume control program.
1. Employee Health
Ultimately, the main goal of any weld smoke and particulate collector is to maintain good workplace air quality for employees. Workers have a right to clean air, and an employer is legally and ethically responsible for doing all that is needed to keep employees healthy. Removing particulate and fumes from the welding shop helps to maintain better workplace morale and enables employees to enjoy longer and healthier careers. Air quality affects more than weld shop workers because employees in surrounding areas of the facility can also suffer from the overflow of fumes.
2. OSHA and EPA Regulations
For welding shops that recirculate the air cleaned by a dust collection system into the workspace, the reintroduced air must stay below OSHA permissible exposure limit (PEL) thresholds for metal contaminants generated by welding processes. Shops that exhaust the air outdoors are subject to EPA emission requirements.
OSHA has established PELs based on an eight-hour time-weighted average (TWA) for hundreds of dusts, including metals contained in welding fumes. They are listed in OHSA’s annotated PEL tables. The OSHA PEL requirements will determine the minimum level of filtration efficiency that a fume collector should achieve. However, even when a facility meets the PELs for its metals, some workers may still suffer from health problems caused by fumes. In this case, operators may have to lower the exposure limits further to protect the air quality and health of all employees.
In 2008, the EPA introduced the National Emission Standards for Hazardous Air Pollutants (NESHAP) Rule 6X as part of the Clean Air Act for metal finishing hazardous air pollutants (MFHAPs). The EPA created these standards to reduce exposures to hazardous air pollutants (HAPs), including materials that contain 1.0 percent by weight manganese, or 0.1 percent by weight cadmium, chromium, lead, or nickel.
3. Protecting Surrounding Equipment
Abrasive metal particles in welding air can migrate into the inner workings and moving parts of surrounding equipment and cause premature failure. In addition, metal dust can migrate into electrical connections in control panels, buss rails and even into surrounding electrical panels and switch gear rooms and can create arc flash dangers for unsuspecting electrical maintenance personnel and even shutting down the production process.
4. Welding Processes
Determining the best dust collection system and configuration depends upon the type of welding processes performed at the shop. For example, contained-booth welding is common with smaller product welding processes or welding of more toxic metals, such as with stainless steel or galvanized material. It is also very common with robot welding cells, which are more protected when the robotic welders are in operation.
Large product welding operations require a large area around the welding operation or high ceilings to accommodate moving products in and out of the welding area. Large rooms or facilities are also used when different products are being welded or any number of welders are working in the same area.
Applications occurring in the same area, such as plasma cutting, grinding, torching and arc gouging, must also be taken into consideration.
5. Types of Material Being Welded
The type and thickness of the material being welded also play a key role in how much smoke and fumes are introduced into the weld shop and surrounding areas. For example, hot rolled steel may have a thin, flakey layer on the surface called mill scale, which is a form of iron oxide. Welding hot rolled steel can produce more fumes than welding cold rolled steel, because the mill scale can vaporize and oxidize in the welding arc.
Stainless steel can contain chromium, nickel and other alloying elements that improve its corrosion resistance. Welding stainless steel can produce a great volume of fume because it requires high welding temperatures that can also vaporize the alloying elements. A byproduct of welding stainless steel is toxic, which has an OSHA PEL of 5 micrograms per cubic meter of air (5 µgm/m3), calculated as an eight-hour time-weighted average (TWA).
Galvanized steel is coated with zinc to prevent rusting. Welding galvanized steel can produce more fumes than welding uncoated steel, because the zinc coating can vaporize and oxidize in the welding arc. Similar to the OSHA PEL for hexavalent chromium, zinc oxide also has a 5-microgram limit over an eight-hour period.
6. How the Material is Being Welded
Different welding processes create different amounts of smoke and fumes, which should be evaluated closely in order to select the correct fume capture system for the application. Welding processes using manual metal arc (MMA), such as stick welding and flux cored wire, tend to produce the most fume.
Other welding processes that produce a lot of smoke and fumes include flux core arc welding (FCAW), shielded metal arc welding (SMAW) and gas or oxy-fuel welding. These processes involve the use of fluxes, coatings or gases that can vaporize and oxidize in the welding arc or flame, creating more fumes than other methods. The fumes can contain various metals, oxides and gases that can pose health risks to the welder and other nearby workers.
7. Size of the Work Area
The size of the welding work area influences the design and implementation of fume control measures. Whether the space is small or large, it is crucial to assess the specific characteristics of the environment and utilize appropriate ventilation systems to minimize worker exposure to welding fumes.
Smaller welding spaces might include booths at technical training shops or a professional shop with a small open-air area where several welders work. Fumes generated in a smaller space can accumulate more quickly, making it essential to have efficient fume extraction to prevent overexposure of workers to hazardous substances. Close proximity to welding operations in smaller work areas may lead to higher concentrations of fumes, necessitating strict adherence to PELs and the use of personal protective equipment (PPE).
Larger spaces often involve numerous welders engaging in welding processes or one open location that contains a welding area. In larger areas, careful planning is required to position fume extractors strategically, considering the layout of workstations and potential sources of fumes. Larger work areas may have more complex airflow patterns, and it may be necessary to strategically position multiple ventilation devices to ensure thorough fume control.
Robotic weld cells come in both large and small booths, either enclosed or open-top. Large robotic welding operations can also involve a traveling robot that moves from one end of the cell to the other.
8. Handling the Collected Air
Welding facility operators also must consider whether the collected air will be cleaned and returned into the facility or exhausted outside.
Recycling the air may require using a secondary high-performance filter with the dust collection system, such as a HEPA filter in order to maintain OSHA PELs for the indoor workplace air. This can be done with an integrated safety monitoring filter system, which is contained in the footprint of the primary dust collector filter housing. Another option is to use a remote monitoring filter system that is a separate housing in line with the ductwork downstream from the main filter housing.
Welding shop operators that choose to exhaust fumes outside are particularly at risk of being in violation of the NESHAP Rule 6X EPA requirement. Older dust collection equipment or HVAC filtration units used to clean the air can also lead to non-compliance if they are not properly designed to handle the process fumes or are using older filter technology.
9. Type of Capture Needed
Hood and source capture systems work well for smaller operations with booth-style setups and welding smaller products. These systems are commonly applied to applications with stainless steel or galvanized welding processes. Portable units can be used at a minimum and should be limited to small processes in the facility. For welding operations beyond small-job welding projects, a portable unit will not keep up with fume production, and it eventually will stop being effective, get pushed to the side and not used at all.
Assess sparks and possible filter ignition sources to prevent fires in the dust collection equipment. Spark arrestors can be added to address this issue.
Ambient dust collection systems are frequently used in expansive workspaces where various operations are conducted. A central unit or multiple smaller collectors filter all the air within the workshop. They can be designed around bridge cranes and overhead equipment. While these systems effectively manage airborne particles within the whole room, it is important to note that they do not eliminate fumes from the welders’ immediate breathing zone. Consequently, workers may need to utilize PPE or use fans to redirect fumes away from their working area.
Ambient systems can be used to push hot air out of work areas that do not have air conditioning. They also help to reduce energy costs by recycling heated or cooled air into the facility.
10. Fume Collector Sizing
Airflow and air exchange are important considerations in controlling weld fumes. Air changes per hour is a calculation of how many times per hour the entire volume of air in a given space is replaced with supply and/or recirculated air. A good starting point is eight to ten air changes per hour in the welding area. If smoke is heavy or plasma cutting and other grinding processes are performed in the area, use faster air change times and lower air-to-cloth filter media ratios (the volume of air flowing through each square foot of filter media every minute).
Low ceilings and smaller rooms concentrate smoke and fumes quicker, so more air changes per hour will be needed. Medium to light smoke in an area with a very high ceiling might be controlled with fewer air changes per hour.
In addition to airflow in the room, consider factors such as ceiling fans, open doors, HVAC-conditioned air entering and leaving the room, as well as individual work area comfort fans. These efforts can all affect how smoke and fumes travel through a room or facility and should be taken into account when evaluating where and how air is collected from the area. When using an ambient type of collection system, it is imperative to know how your building works in the summer and winter time. Key questions to answer are: what type of heating system is used, what type of air conditioning system is used, and if there is no air conditioning, where are the exhaust fans and intake louvers located?
Ceilings also play an important role in controlling airborne particulates. Welding fumes will rise along sloped ceilings. Utilizing the higher points in a building’s roof area will help to ensure successful capture of the smoke. Use of ceiling-to-floor curtains around the perimeter of weld areas or booths can help to contain smoke in a collection area if needed and can be used to isolate areas in large plants.
Wide, clear, solid panels situated around the welding cell can also help with welding flash protection for employees in the area. Locating the smoke and fume collector outdoors not only saves floor space, it is safer with regard to fire protection.
Summing It Up
Maintaining healthy, compliant indoor air quality in welding facilities is a necessary component to a properly run operation. A well-designed weld fume and smoke collection system will change the accepted clean air culture in an industry setting. Employees will embrace the change it makes in their lives and will be the first to raise the flag when the system is not doing its job.
This article originally appeared in the February/March 2024 issue of Occupational Health & Safety.