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Welding is a construction process that fuses two or more parts through heat, pressure, or both. It is an elementary fabrication process used in various industries such as construction, mechanical installations, machinery production, and the oil/gas industry. Metals and thermoplastics are the most common materials merged by welding, but welding can fuse a broad range of materials. However, welding does not come without its hazards. Welders are one of the most endangered professions to workplace hazards. In addition to conspicuous risks of high-heat and bright sparks, toxic fumes are another hazardous factor of welding that is often overlooked. The welding process produces smoke that contains harmful metal fume and gas by-products. This smoke can be damaging to the respiratory tract.
Types of Welding
There are two main types of welding: fusion and pressure. Fusion welding uses heat, while pressure welding utilizes both heat and pressure. Arc, gas, and thermite welding are the three subcategories of fusion welding, which is the most used technique.
Arc welding gets its name from the electric arc located at the tip of the welding torch. Arc generates high levels of heat, melting the metals to fuse them. The electric arc which melts the metals needs to be protected by a layer of inert gas. Argon, helium, nitrogen, and carbon monoxide are the most used shielding gases for arc welding.
Other techniques such as gas and thermite welding utilize a variety of gases as well. Gas welding is the process of fusing metals with an open flame coming out of a torch. This technique burns gases with high-calorie content such as acetylene to achieve needed high-temperature levels. Thermit welding uses a chemical reaction to produce intense heat instead of gas fuel or electric current.
In addition, toxic fumes may release from the metals during welding. Most metals and alloys have hazardous content that generates poisonous fumes under high temperatures.
All the gases mentioned can be perilous for workers, especially when combined.
Health Effects of Welding Fume
The health effects of welding fumes vary on the exposure time, frequency, and chemical content. Acute exposure to welding fumes causes may lead to eye, nose, and throat irritation, dizziness, and nausea. Prolonged exposure can cause lung damage and certain types of cancer.
Certain fumes can cause metal fever, a health condition that displays flu-like symptoms. Welders who are exposed to metal fumes regularly report that they experience the symptoms of chills, fatigue, aches, and pain.
Manganese fumes can be particularly threatening. Workers with high levels of manganese fumes exposure display Parkinson’s-like symptoms. Common symptoms of manganese fume exposure may include difficulty gaining balance, uncontrollable shaking, and stiffness.
Gases such as helium, argon, and carbon dioxide displace oxygen in the air and can lead to suffocation, particularly when welding in confined or enclosed spaces. As such, carbon monoxide gas can form, posing a deadly asphyxiation hazard.
The health effects of certain substances are listed in the table given below.
|Fume Type||Source||Health Effect|
|Aluminum||Aluminum component of some alloys, e.g., Inconel, copper, zinc, steel, magnesium, brass and filler materials.||Respiratory irritant.|
|Beryllium||Hardening agent found in copper, magnesium, aluminum alloys and electrical contacts.||“Metal Fume Fever.” A carcinogen. Other chronic effects include damage to the respiratory tract.|
|Cadmium Oxides||Stainless steel containing cadmium or plated materials, zinc alloy.||Irritation of respiratory system, sore and dry throat, chest pain and breathing difficulty. Chronic effects include kidney damage and emphysema. Suspected carcinogen.|
|Chromium||Most stainless-steel and high-alloy materials, welding rods. Also used as plating material. Converts to hexavalent chromium during welding.||Increased risk of lung cancer. Some individuals may develop skin irritation. Some forms are carcinogens (hexavalent chromium).|
|Copper||Alloys such as Monel, brass, bronze. Also some welding rods.||Acute effects include irritation of the eyes, nose and throat, nausea and “Metal Fume Fever.”|
|Fluorides||Common electrode coating and flux material for both low- and high-alloy steels.||Acute effect is irritation of the eyes, nose and throat. Long-term exposures may result in bone and joint problems. Chronic effects also include excess fluid in the lungs.|
|Iron Oxides||The major contaminant in all iron or steel welding processes.||Siderosis – a benign form of lung disease caused by particles deposited in the lungs. Acute symptoms include irritation of the nose and lungs. Tends to clear up when exposure stops.|
|Lead||Solder, brass and bronze alloys, primer/coating on steels.||Chronic effects to nervous system, kidneys, digestive system and mental capacity. Can cause lead poisoning.|
|Manganese||Most welding processes, especially high-tensile steels.||“Metal Fume Fever.” Chronic effects may include central nervous system problems.|
|Molybdenum||Steel alloys, iron, stainless steel, nickel alloys.||Acute effects are eye, nose and throat irritation, and shortness of breath.|
|Nickel||Stainless steel, Inconel, Monel, Hastelloy and other high-alloy materials, welding rods and plated steel.||Acute effect is irritation of the eyes, nose and throat. Increased cancer risk has been noted in occupations other than welding. Also associated with dermatitis and lung problems.|
|Vanadium||Some steel alloys, iron, stainless steel, nickel alloys.||Acute effect is irritation of the eyes, skin and respiratory tract. Chronic effects include bronchitis, retinitis, fluid in the lungs and pneumonia.|
|Zinc||Galvanized and painted metal.||Metal Fume Fever.|
|Gas Type||Source||Health Effect|
|Carbon Monoxide||Formed in the arc.||Absorbed readily into the bloodstream, causing headaches, dizziness or muscular weakness. High concentrations may result in unconsciousness and death|
|Hydrogen Fluoride||Decomposition of rod coatings.||Irritating to the eyes and respiratory tract. Overexposure can cause lung, kidney, bone and liver damage. Chronic exposure can result in chronic irritation of the nose, throat and bronchi.|
|Nitrogen Oxides||Formed in the arc.||Eye, nose and throat irritation in low concentrations. Abnormal fluid in the lung and other serious effects at higher concentrations. Chronic effects include lung problems such as emphysema.|
|Oxygen Deficiency||Welding in confined spaces, and air displacement by shielding gas.||Dizziness, mental confusion, asphyxiation and death.|
|Ozone||Formed in the welding arc, especially during plasma-arc, MIG and TIG processes.||Acute effects include fluid in the lungs and hemorrhaging. Very low concentrations (e.g., one part per million) cause headaches and dryness of the eyes. Chronic effects include significant changes in lung function.|
Source and Health Effect of Welding Gases
|Gas Type||Source||Health Effect|
|Aldehydes (such as formaldehyde)||Metal coating with binders and pigments. Degreasing solvents||Irritant to eyes and respiratory tract.|
|Diisocyanates||Metal with polyurethane paint.||Eye, nose and throat irritation. High possibility of sensitization, producing asthmatic or other allergic symptoms, even at very low exposures.|
|Phosgene||Metal with residual degreasing solvents. (Phosgene is formed by reaction of the solvent and welding radiation.)||Severe irritant to eyes, nose and respiratory system. Symptoms may be delayed.|
|Phosphine||Metal coated with rust inhibitors. (Phosphine is formed by reaction of the rust inhibitor with welding radiation.)||Irritant to eyes and respiratory system, can damage kidneys and other organs.|
Source and Health Effect of Organic Vapors as a result of Welding
Source: Tables 1 to 3 are from Work Safe Alberta’s Welder’s Guide to Hazards of Welding Gases and Fumes, 2009
Regulations and Preventative Measures
According to The Occupational Safety and Health Administration Standard No: 1926.353, the permissible exposure limit (PEL) to welding fumes is 5 mg/m3. As the first line of safety, employers must ensure that welders are not exposed to toxic fumes above permitted limits.
Like all workplace hazards, correct use of face and skin protectors is crucial to prevent the health risks of welding fumes. The Occupational Safety and Health Administration suggests that workers performing welding, cutting, or heating shall wear suitable protective equipment.
Employers must ensure that exposed workers are properly informed through informative training as required by OSHA’s Hazard Communication standard.
According to OSHA regulations, the permissible exposure limit (PEL) to welding fumes is 5 mg/m3. Workers should position themselves to avoid breathing welding fume and gases.
Welding surfaces should be cleaned of any coating that could potentially create toxic exposure, such as solvent residue and paint. If the work area is enclosed, proper ventilation and air circulation must be ensured to avoid the build-up of toxic fumes. If a large-scale ventilation system is not available, local exhaust can be used.
Fume hoods, extractor guns, and vacuum nozzles can be utilized to remove hazardous gases from the worker’s personal breathing area. Care must be taken to ensure that the outlets of local exhausting systems are not contaminating other worker’s breathing zone. Respiratory protection may be required if work practices and ventilation do not reduce exposures to safe levels.
After considering all of the possible preventative measures, it’s important to note that the best prevention technique is prevention at the source. If possible, welding techniques and metals that don’t involve hazardous gases must be considered.
Welders are one of the most exposed professions when it comes to workplace-related health issues due to the involvement of toxic fumes in welding. However, the hazards of welding fumes can be efficiently prevented by following recognized international standards.