Welding is the most common method of joining metals in industry today. When welded, two parts of similar metals are melted together. Once completed, the welded joint is as strong or stronger than the pieces from which the joint is formed. Welding covers a temperature range 800ºC – 1635ºC. General hazards of welding include impact, penetration, harmful dust, smoke, fumes, intense heat and light radiation. The proper personal protective equipment can protect you from these hazards !
Welding health hazards – chemical agents
Generally, welding fumes and gases come from the base material or filler material; paints and coatings on the metal and covering the electrode; shielding gases; chemical reactions from arc ultraviolet light and heat; process and consumables; and contaminants in the air, such as vapors from cleaners and degreasers.
Welding fume exposure in the workplace is a serious occupational hazard and can cause numerous health problems. (for more Info see „Health hazards“ chapter). The highest risk factors include ozone, chromium particularly in its hexavalent state (Cr 6+ ), nickel (potential carcinogens), cadmium and lead. Cadmium in welding fumes can be fatal in a short time. Ultraviolet radiation given off by welding reacts with oxygen and nitrogen in the air to form ozone and nitrogen oxides, which are deadly at high doses, irritate the nose and throat, and cause serious lung disease.
Ultraviolet rays can react with chlorinated hydrocarbon solvents, such as trichloroethylene; 1,1,1,-trichloroethane; methylene chloride, and perchloroethylene, to form phosgene gas, a deadly substance, even at small amounts. The symptoms of exposure, dizziness, chills, and cough usually take five or six hours to appear. One single welder produces 20-40 g fumes per hour which corresponds to about 35-70 kg of weldimg fume per year. (The OEL of general welding fume is 5mg/m3.)
Welding health hazards – physical agents
Electric arc and laser welding emit ultraviolet (UV), visible light and infrared (IR). Gas welding and gas cutting emit visible light and IR radiation. The potential effect of radiation on the body depends on the type and intensity of radiation, the distance you are from it and the duration of exposure.
Ultraviolet radiation (UV) is generated by the electric arc in the welding process. Skin exposure to UV can result in severe burns, in many cases without prior warning. UV radiation can also damage the lens of the eye. Many arc welders are aware of the condition known as „arc-eye,“ a sensation of sand in the eyes.
Exposure to infrared radiation (IR), produced by the electric arc and other flame cutting equipment may heat the skin surface and the tissues immediately below the surface. Except of this effect, which can progress to thermal burns in some situations, infrared radiation is not dangerous to welders. Most welders protect themselves from IR (and UV) with a welder‘s helmet (or glasses) and protective clothing.
Intense visible light
Exposure of the human eye to intense visible light can produce adaptation, pupillary reflex, and shading of the eyes. These actions are protective mechanisms to prevent excessive light from being focused on the retina. In the arc welding process, eye exposure to intense visible light is prevented for the most part by the welder‘s helmet. However, some individuals have sustained retinal damage due to careless „viewing“ of the arc. At no time should the arc be observed without eye protection.