AN EDUCATION IN WELDING FUME EXTRACTION

Welding is everywhere. It?s performed outdoors at 37 stories up on a high-rise construction project and on the ground repairing a backhoe loader. Manufacturers are welding in their shops, and home hobbyists in their garage. Regardless of where you?re welding, it?s essential to follow safe practices, including wearing long sleeves and pants, safety glasses and a welding helmet, being aware of electrical hazards and welding in an area free of flammable materials. Another important factor to consider ?
Is the control of fumes and gases produced when welding.

If safe practices are not followed, overexposure to welding gases and fumes can occur which has the potential to cause health problems, which is why it is important for welders to make safe practices a part of their work habits. With that in mind, let?s take a more detailed look at the use of welding fume extraction to control welding fume exposures and why it?s important and how you can protect yourself and your employees.

There are a number of variables that contribute to fume and gas generation, including the welding process (Stick, MIG, TIG, etc.), shielding gas, consumable, the base material and its coating, and other possible contaminants in the air and on the materials. The plume contains very fine particles from the consumables, base metal and base metal coatings.

There are some basic steps which should be taken to identify potentially hazardous substances in the welding environment. First, read the product label and material safety data sheet (MSDS) for the electrode to what substances can be reasonably expected in the welding fume and to determine if special ventilation is required. Secondly, know what the base metal is, and determine if there is any paint, plating or coating that could expose you to toxic fumes and/or gases. If possible, remove the coating from the metal being welded.

For common mild steel arc welding, depending on the amount and length of exposure to these fumes, immediate or short-term effects are generally temporary and can include burning eyes and skin, dizziness, nausea and fever. Long-term exposure to welding fumes can lead to siderosis (iron deposits in the lungs) and may affect pulmonary function. Bronchitis and some lung fibrosis have been reported.

The gases used during arc welding also present a potential hazard. Most of the shielding gases (argon, helium and carbon dioxide) are non-toxic, but as they are released, they can displace oxygen in your breathing space, potentially causing dizziness, unconsciousness and death in very hazardous situations. Carbon monoxide is one of the several gases that can develop and pose a hazard in excessive levels.

Now let?s examine the steps to take and equipment needed to control exposure to welding fumes and gases.

BASIC SAFETY PRECAUTIONS

The easiest way to reduce the risk of hazardous fumes and gases is to keep the welders head out of the fume plume. But the failure to follow this advice may cause overexposure to substances in the fume because the concentration of fumes and gases is greatest in the fume plume. You can control exposure to fumes and in the breathing zone and general area using natural ventilation, mechanical ventilation, fixed or moveable exhaust hoods or local exhaust at the arc. It might also be necessary to wear an approved respirator if ventilation has been installed and is not capable of controlling exposures to applicable limits. The most accurate way to ensure exposure does not exceed applicable ranges is to have an industrial hygienist analyze a sample of the air you are breathing. This is particularly important if you are welding with stainless, hardfacing or products that require special ventilation.

Next, let?s examine methods to control welding fume exposure.

PROTECTING WORKERS
The particular type of ventilation or exhaust needed for your application depends on a number factors, including workspace volume, workspace configuration, number of welders, welding processes and current, consumables used, the applicable exposure limits, material welded and natural airflow.

Natural ventilation. Natural ventilation is the movement of air through the workplace caused by natural forces such as the flow of fresh air through open doors and windows. According to OSHA regulations, when welding and cutting (mild steels), natural ventilation is usually considered sufficient provided that:
? A room or welding area contains at least 10,000 cubic feet (about 22 ft x 22 ft x 22 ft) for each welder.

? The ceiling height is not less than 16 ft.

? Cross ventilation is not blocked by partitions, equipment or other structural barriers.

? Welding is not done in a confined space. Spaces not meeting these requirements should be equipped with mechanical ventilating equipment.

Mechanical ventilation and source extraction equipment. Mechanical ventilation (use of a portable or fixed fan) is an effective method of general fume control, however it is not as effective in controlling individual work station exposures. The local exhaust of welding fumes is an effective method of controlling work station exposures and can be provided by a mobile or stationary, single or multi-station, exhaust or filtration equipment designed with adjustable extraction arms, nozzles or guns. It can also include fixed enclosures, booths or tables with extraction canopies (also known as down-draft) or by back-draft or cross-draft tables/booths.

Local exhaust falls into two categories: low vacuum/high volume or high vacuum/low volume. Mobile or stationary, single or multi-station, large centralized exhaust or filtration equipment designed with adjustable arms are usually low vacuum/high volume systems. When positioned correctly, the capture rate of adjustable fume extraction arms (6 in to 12 in) is suitable for all welding and cutting.

High vacuum/low volume systems are designed for close proximity (2 in to 4 in) positioning. It is achieved with lower airflow rates than those encountered when using a low vacuum system. In order to be effective it must be properly located near the arc at all times. Fume extraction is only one component of reducing welding fume. You should also consider the selection of the welding process, welding procedure and consumable. Many times a combination of fume extraction, training, process change and/or consumable change is needed to reduce the amount of fume to acceptable levels.

Solutions to a particular application may involve one or all of these factors, and you must determine which solution best fits your application and work environment. Confirm that the ventilation is adequate by having an industrial hygienist exposures after any changes or improvements are make.

WHERE TO BEGIN
Teaching safe welding practices in the classroom, is one of the best ways to ensure that welders understand the use of proper ventilation and fume control when they?re on the job. The following is a description of training use at a welding school and two union training programs integrating safe ventilation and fume control practices into their curriculum and labs.

Eastern Wyoming College
(Torrington, WY)
Eastern Wyoming College pulls students from a five-state area to its Welding & Joining Technology Program, which experienced such significant growth that in 2006 it invested $1 million to built a second welding lab. Graduating students leave the program as American Welding Society (AWS)-certified welders. The program, led by three AWS-certified instructors, incorporates safety and health and training into every part of its curriculum from the first day a student steps into the lab. When it came to constructing the new lab with 19 welding booths, the first piece of equipment the school purchased and installed was a high-vacuum/low volume, self-cleaning central fume extraction system, an X-Tractor® 52.

?The safety of our students, instructors and visitors is paramount,? says Leland Vetter, senior welding instructor. ?We use more than 10,000 pounds of consumables a year, and we?re working with students at all different experience levels. The X-Tractor® is easy to use and integrate into our teaching of safety first.?

Sheet Metal Union Workers? Local Union No. 33
(Cleveland, OH)
Sheet Metal Union Local 33 represents more than 4,500 members throughout Ohio and West Virginia. 70 percent of the union?s members work in commercial HVAC, where welding is commonly used on the job. Apprentices receive 48 hours of hands-on welding lab work where they learn primarily stick, MIG and TIG welding. Classes are also open to journeymen for refresher courses. The union recently built a new regional headquarters and training facility in Cleveland, which includes a new welding lab with 19 booths. Along with new MIG and TIG welders, the union installed two new low vacuum/high volume Statiflex® 6000 central fume extraction systems.

?Our apprentices are taught safe work practices at every stage of their training in the classroom, in the lab and on the jobsite. This includes welding,? explains John Nesta, Local 33?s training coordinator and an AWS-certified instructor. ?With the new welding lab, we wanted the latest and safest welding technology and equipment available. The Statiflex® systems allow us to effectively control fumes in close quarters.?

Southeast Wisconsin Carpentry Union 1074
Eau Claire, WI
The Southeast Wisconsin Carpentry Union trains carpenters, millwrights, pile drivers, floor covers and cabinet makers. And while welding might not seem a skill used by professionals working primarily with wood, union members are required to be familiar with basic welding processes. ?Because of where our members work during the construction process, we often come across situations where welding is required. It can include making structural attachments to curtain walls or welding attachments,? states Joe Weisling, training director.

The union was constructing a new training center, and because of its location, faced constraints on the amount of noise it was allowed to generate. This was a factor when the union was selecting a welding fume extraction system for 12 welding stations. ?We purchased a Statiflex® system. The decibel rating was the deciding factor,? Weisling explains. ?And it also has a great auto-start feature on the fan, which is especially beneficial when teaching welding due to ease of use.?

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Tim Rosiek is a product/applications engineer for environmental systems at The Lincoln Electric Company, 22800 Saint Clair Avenue, Cleveland, OH 44117-8542, 216) 383-2692, Fax: 216) 383-4727, www.lincolnelectric.com, rosiek@lincolnelectric.com.