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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 dan- gers for unsuspecting electrical mainte- nance personnel and even shutting down the production process. 4. Welding Processes Determining the best dust collection sys- tem and configuration depends upon the type of welding processes performed at the shop. For example, contained-booth welding is common with smaller prod- uct welding processes or welding of more toxic metals, such as with stainless steel or galvanized material. It is also very com- mon with robot welding cells, which are more protected when the robotic welders are in operation. Large product welding operations re- quire a large area around the welding op- eration 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, be- cause the mill scale can vaporize and oxi- dize 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 al- loying 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 un- coated 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-micro- gram limit over an eight-hour period. 6. How the Material is Being Welded Different welding processes create differ- ent 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 pro- duce 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 vapor- ize and oxidize in the welding arc or flame, creating more fumes than other methods. The fumes can contain various metals, ox- ides and gases that can pose health risks to the welder and other nearby workers. 7.SizeoftheWorkArea The size of the welding work area influ- ences 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 environ- ment and utilize appropriate ventilation systems to minimize worker exposure to welding fumes. Smaller welding spaces might include booths at technical training shops or a pro- fessional shop with a small open-air area where several welders work. Fumes gen- erated in a smaller space can accumulate more quickly, making it essential to have efficient fume extraction to prevent overex- posure of workers to hazardous substances. Close proximity to welding operations in smaller work areas may lead to higher con- centrations 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 strate- gically, considering the layout of worksta- tions and potential sources of fumes. Larger www.ohsonline.com FEBRUARY/MARCH 2024 | Occupational Health & Safety 41 Cut labor costs for safety shower testing by 80%. www.greengobblersafety.com