Avoid Hazards by Welding Safely

March 1, 1999
Arc welding is a safe process when sufficient measures are taken to protect the welder from potential hazards and when proper operating practices are

Arc welding is a safe process when sufficient measures are taken to protect the welder from potential hazards and when proper operating practices are followed. However, if potential dangers are overlooked, welding operators can face major hazards in the form of fumes and gases, arc rays and sparks, and electric shock.

Here are a few of the main precautions that will help welding operators avoid trouble. Rental counter personnel should be prepared to instruct renters of welding equipment on safe welding practices. Everyone with welding responsibility should also be familiar with ANSI standard Z49.1, "Safety in Welding and Cutting."

Silent hazards The fumes and gases that result from the welding process can cause acute or chronic health effects if proper precautions are ignored. The fume plume contains solid particles from the consumables (electrodes), base metal, base metal coating and gases formed in the process, which include oxides of nitrogen and ozone. The gases used for shielding (argon, helium and carbon dioxide) are nontoxic, but as they are released, they displace oxygen. This can cause dizziness, unconsciousness and even death with longer exposures. Avoid exposure to fumes and gases whenever possible, and use ventilation equipment or a respirator when necessary.

Here are some suggestions to help welding operators avoid exposure:

* Operators should always keep their heads out of the fumes.

* Always use enough ventilation or exhaust to remove fumes and gases from the work area. Mechanical equipment should exhaust at least 2000 cfm of air for each welder, except where individual exhaust hoods, booths or air-line respirators are used.

Natural ventilation may be used under certain conditions. For welding or cutting mild steel, natural ventilation is usually sufficient if a room has at least 10,000 cubic feet per welder, with a ceiling height of at least 16 feet. Cross-ventilation should not be blocked, and welding should not be done in a confined space.

* Don't get too close to the arc. Operators should use corrective lenses to help them maintain the proper distance if necessary.

* Read and understand the Material Safety Data Sheets (MSDS) for the product.

* Read and obey warning labels on all containers of welding materials.

* Use a smoke extractor-type welding gun for semiautomatic welding processes.

Arc rays and sparks Arc rays and sparks are the most obvious hazards because they are the most visible and can seriously injure eyes and burn skin. However, they should not be taken for granted. While the dangers may be well-recognized, the following precautions should always be taken:

* Protect eyes and face with a properly fitted welding helmet that is equipped with the correct grade of filter plate (See ANSI Z49.1 and Z87.1 standards). Infrared radiation can cause retinal burning and cataracts. Even brief exposure to ultraviolet (UV) radiation can cause an eye burn known as "welder's flash," which results in extreme discomfort, swelling, fluid excretion and possibly temporary blindness.

* Protect the body from welding spatter and arc flash with clothing made from durable, flame-resistant material, such as woolen fabrics, and gear that includes flameproof apron and gloves, leather leggings and high boots. Avoid clothing made of synthetic materials, which can melt when exposed to extreme heat or sparks, or of cotton, unless it is specially treated for fire protection. Keep clothes free of grease and oil, which may ignite.

* Protect others from spatter, flash and glare with nonflammable protective screens or curtains.

* Be sure to wear safety glasses with side shields when in a welding area.

Electric shock can kill The hazards of electric shock are one of the most serious risks facing a welder. Contact with equipment or metal parts that are electrically "hot" can cause injury or death from the shock or from a fall that results from reaction to the shock. Primary voltage shock (i.e., 230-460 volts) is the most serious danger because it is much greater than secondary voltage shock (i.e., 60-100 volts). Primary voltage shock comes from touching a lead inside the welding power source when the operator has his body or hand in contact with the welder case or other grounded metal.

The following precautions should always be taken:

* Turning the equipment's power switch to the off position does not turn off power inside the case. Never remove panels without unplugging the input power cord or turning off the power disconnect switch. Secondary voltage shock comes from touching part of the welding circuit, such as a bare spot on the electrode cable, while also touching the grounded metal workpiece.

* Avoid touching both parts of a circuit at the same time.

* The operator must be sure he is insulated from the workpiece and ground, as well as other live electrical parts.

* Don't lean on the workpiece. Use plywood, rubber mats or other dry insulation to stand on, and wear dry, hole-free gloves.

* Stay dry, and do not weld when wet. Never dip the electrode in water to cool it.

* Check equipment to be sure it is properly grounded, in good repair and installed according to prevailing codes.

* Be sure equipment is turned off when not in use.

Electric current flowing through a conductor causes electric and magnetic fields (EMFs), which can interfere with pacemakers and may affect health in other ways. Customers should be cautioned to consult their physician before arc welding if they have a pacemaker.

To avoid excessive exposure to EMFs, keep the electrode and work cables together. The operator must never place his body between the two cables or coil the electrode lead around his body. Never work directly next to the welding power source.

Other hazards Welding sparks can cause fire or explosion, and can easily go through small cracks and openings or spray up to 35 feet to adjacent areas. Remove fire hazards from the welding area or cover them with a fire-resistant shield if necessary. Do not weld near unshielded fuel or hydraulic lines.

Cylinders used for shielding gas in some processes can explode if handled improperly. Always store and handle them safely, keep them upright, and protect them from mechanical shocks or falling. Maintain all hoses, fittings and regulators in good condition. Never allow the electrode or any electrically "hot" parts of the welding equipment to touch a cylinder.

Do not weld near fumes from other processes, such as cleaning, degreasing or painting. Some fumes may cause an explosion; others can form highly toxic gases when exposed to welding arcs and heat.

Ear plugs or muffs will help prevent hearing loss from working around noisy arc welding equipment or some processes. They also will keep flying sparks out of the ears, especially when welding overhead or in close quarters. Hearing loss can be gradual and will add up over time, so ear protection is always a good idea.

Welding is indispensable to numerous industrial and consumer products, as it plays a key role in building and maintaining equipment, tools and infrastructure. Done properly, it is safe, productive and efficient. Poor safety techniques often translate into poor quality and can pose a hazard to operators and other people in the area. Insistence on strict safety requirements for welding operations will pay off in employee health and productivity.