Welding, cutting and brazing are hazardous activities that pose a combination of both safety and health risks to millions of workers in a wide variety of industries. According to OSHA the risk of fatal injuries is more than 4 deaths per 1000 workers over a working lifetime. In order to protect workers during these operations depends upon understanding the hazards involved and methods of control.
Welding joins pieces of metal by use of heat, pressure or both. The most common types of welding includes arc welding, MIG, TIG, plasma arc and submerged arc welding. Other welding processes may use oxy-acetylene gas, electrical current, lasers, electron beams, friction and chemical reactions.
Brazing involved joining piece s of metal together by use of a metal or alloy which has a lower melting point than the metal pieces being joined. The filler materials may contain lead or cadmium.
Cutting involves heating the metal with a frame and directing a stream of oxygen along the line to be cut.
There are a number of health hazards associated with welding. Welding smoke is a mixture of very fine particles termed fumes and gasses. Many of the substances that make up welding smoke are extremely toxic. This includes chromium, nickel, arsenic, manganese, beryllium, cadmium, silica, nitrogen oxides, cobalt, copper, lead, ozone, selenium and zinc. The welding fumes and gasses come from a variety of sources including:
- The base metals being welded;
- The filler material that is used;
- Coatings and paint o the metal being welded;
- Chemical reactions resulting from the ultraviolent light from the arc and the heat that is generated;
- Contaminants such as cleaners, degreasers, oils on the metals.
The health effects of welding, brazing and cutting exposures are difficult to list. The fumes may contain a varied number of substances known to be harmful. The individual components of the fumes can affect almost and pat of the body. Health effects may be short or long term. Short term acute effects include:
- Exposure to metal fumes can cause metal fume fever. This normally comes from zinc, magnesium, copper and copper oxide. It can result from welding, brazing, cutting or even heating wires or other metal forms. Symptoms of metal fume fever may occur 4-12 hours following an exposure. These symptoms may include chills, thirst, fever, muscle ache, coughing, wheezing, fatigue, nausea, and a metallic taste in the mouth.
- Fumes and smoke can irritate the eyes, nose, chest and respiratory tract. This can cause coughing, wheezing, shortness of breath, bronchitis, pulmonary edema and pneumonitis. Gastrointestinal effects include nausea, vomiting, cramps, loss of appetite and slow digestion.
- Cadmium is sometimes a component of fumes and f the concentration is sufficient can be a fatal exposure. UV radiation produced by welding may react with oxygen and nitrogen in the air to form ozone and nitrogen oxides. These gasses are deadly at high does and can irritate the nose and throat and cause serious lung damage.
- UV radiation produced by welding can react with chlorinated hydrocarbon solvents to form phosgene gas. Even a small amount of propene can be fatal. Early symptoms of exposure such as dizziness, chills, and cough may take 5-6 hours to appear. Welding should never be done anywhere near solvents or degreasing equipment.
Long term or chronic health effects include:
- Welders, brazers and metal cutters have an increased risk of lung, larynx and urinary tract cancer. Metal smoke and fumes may contain carcinogenic materials such as cadmium, nickel, beryllium, chromium and arsenic.
- Chronic respiratory problems may result from exposure. These include bronchitis, pneumonia, emphysema, pneumoconiosis, decreased lung capacity, silicosis and silicosis.
- Other health problems related to metal fume exposure including heart disease, gastritis, gastrouodentis and ulcers of the stomach and small intestines.
- There are reproductive hazards related to exposure. An increase in miscarriages and delayed conceptions occur among welders or their spouses. Studies indicate that welders who work with stainless steel had poor sperm quality compared to men who did other work.
The heat associated with welding, brazing and cutting can present a significant hazard. Burns can result from high, heat, hot slag, metal chips, sparks and hot electrodes.
- Exposure to heat can cause heat stress or stroke. The symptoms are fatigue, dizziness, nausea, abdominal pain and irritability. Good general ventilation, shielding, rust breaks and plenty of fluids will help to prevent heat related illnesses.
- Invisible ultraviolent light from the welding can cause welders flash even following an exposure of less than one minute. The symptoms usually occur several hours after UX exposure and include a fueling of sand in the eyes, blurred vision, pain, tearing, burning and a headache.
- About half of welders flash injuries occur in workers who are not welding. They arc can reflect off nearby materials and injure others.
- Exposure to UN light can cause burns similar to sunburn and increase the risk of skin cancer.
- The intense light associated with arc welding can cause damage to the retina of the eye.
- Infrared radiation may damage the corner and result in the formation of cataracts.
Metal workers have a high incidence rate of musculoskeletal problems including back injuries, shoulder pain, tendonitis, carpal tunnel, white finger and knee joint issues. Work postures and heavy lifting contribute significant to these problems. These issues could be prevented by following a new work practice techniques.
- Do no work in one position for long periods of time;
- Keep the work at a comfortable height;
- Locate tools and materials conveniently;
- Minimize vibration
There are a number of safety hazards associated with welding, brazing and cutting. These are generally related to electrical hazards, fire and explosions, dangerous machinery and falls.
Even though welding general uses low voltage there is a possibility of electrical shock. The likihood of a shock may be increased by conditions such as wet or cramped spaces. Accidents can result from even a small shock. Dry gloves should be used to protect against electrical shock. The worker should wear rubber solid shoes and use an insulated layer for protection on surfaces that conduct electricity. The work piece being used and all electrically powered machines must be grounded. Electrodes should not be changed with bare hands, wet gloves, while standing on wet floors or grounded surfaces.
The Intense heat and sparks which are produced can cause fires if combustibles or flammable materials are in the area. Welding, brazing or cutting should only be performed in areas that are free of combustible materials including trash, wood, paper, textiles, plastics, chemicals and flammable materials. Containers that have held a flammable or combustible material should never be welded, brazed or cut unless it has been thoroughly cleaned or filled with an inert gas. Explosions, fires or sudden release of toxic vapors may result. Containers with unknown contents are assumed to be flammable. Fire extinguishers should be located nearby when welding, brazing or cutting.
A confined space is an area with limited access which normally as little or not ventilation. Dangerous concentrations of toxic fumes and gasses can build up very quickly. Suffocation can occur because welding, brazing and cutting can use up or displace oxygen in the air. Workers who enter or work in a confined space should follow the Confined Space Guidelines which are available from EHS or on the EHS web site.
The first step prior to a welding, brazing or cutting job is to identify the hazards associated with a partial task. The hazards will depend on the type of work, the materials used and the environmental conditions. Once the hazard is identified the appropriate control methods are implemented.
Engineering controls and work practices are the preferred method of controlling employee exposure and melting hazards. Among the engineering controls which should be examined are:
- Substitution with less hazardous materials if possible.
- Local exhaust and ventilation removed fumes and gasses at the source. This is the most effective ventilation control method. Exhaust ventilation can be provided by a partial enclosure, hoods or capture ducts.
- General ventilation is a minimum requirement for welding, brazing and cutting operations. This uses roof vents, fans, open doors, windows and other means to increase the general ventilation rate.
- Shielding should be used to protect others in the area from light, heat and hot metal spatter
- Welding booths should be painted with a dull finish that doesn’t reflect UV light.
Work practices can be modified to eliminate or mitigate hazards. Among the work practice changed to be considered are:
- Do not weld or cut painted on couted ports. Remove surface coatings prior to work.
- Use a water table under the plasma arc cutting to reduce fume and noise levels.
- Minimize light and fumes produced by welding as much as possible.
- Position yourself so that your breathing zone is not in fumes.
- Remove all nearby flammable or combustibles prior to starting work.
- Make sure all equipment is properly maintained.
- Keep work area free of equipment, supplies and other items that could cause trips or falls.
- Use the lowest amperage possible when welding.
Personal protective equipment (PPE) may be used along with but never in place of engineering controls and work practices. Among the PPE required for welding, brazing and cutting operations are eye protection and protective clothing.
Eye protection must be worn to protect from bright lights, heat, UV light and flying sparks. Helmets, goggles and other eye protection must have lenses for exposure to welding, cutting or brazing.
Protective clothing should be worn by workers welding, cutting or brazing. The clothing should include:
- Leather shoes
- Leather apron
- Flame retardant clothing
Protective clothing should be made of treated cotton fabric and approved for use in these applications. Sleeves and collars should be kept buttoned. Pants and shirts should not be cuffed.
Hearing protection may be needed, as well as respirators in certain situations.
Welding emissions can be very hazardous. Because of this NISOH recommends that workers involved in welding, cutting and brazing on a routine basis should receive annual medical exams. An eye exam should be part of the annual physical.