Occupational hazards and prone occupational diseases
Occupational hazards are related to the health and safety of workers and the overall situation of economic development and social stability. In today's rapid economic development in my country, electric welding operations involve almost all industrial fields. The number of electric welders has risen sharply. The distribution of electric welding operations is very wide, but the largest number of electric welding workers are in ships, vehicles, steel structures and boiler manufacturing. When welding in poorly ventilated or closed containers such as hull equipment, boilers or oil tanks, the concentration of dust in contact with electric welding is high, and the occupational hazards in electric welding are becoming increasingly prominent. The main occupational hazards of electric welding for special operations are dust, toxic gases, high temperature, arc light, high-frequency electromagnetic fields, etc.
???1. Main hazards in electric welding
???1. The danger of metal fume The composition of electric welding fume varies depending on the electrode used. The electrode is composed of welding core and coating. In addition to a large amount of iron, the welding core also contains carbon, manganese, silicon, chromium, nickel, sulfur, and phosphorus. The material in the drug coating is mainly composed of marble, fluorite, rutile, pure salt, water glass, ferromanganese, etc. During welding, the arc discharge generates a high temperature of 4000 ° C to 6000 ° C. While melting the electrode and the weldment, a large amount of smoke is generated. Its composition is mainly iron oxide (mainly iron oxide, accounting for 36% -76%) ), Manganese oxide, silicon dioxide, silicate, fluoride, ozone and nitrogen oxides, etc., soot particles are diffused in the working environment and are easily drawn into the lungs. Long-term inhalation will cause fibrotic lesions of the lung tissue, known as the welder's pneumoconiosis, and is often accompanied by manganese poisoning, fluorine poisoning, and metal fume fever. The welder's pneumoconiosis has a slow onset, mainly manifested as chest tightness, chest pain, shortness of breath, cough, sputum and other respiratory symptoms, accompanied by headaches, general weakness and other symptoms, but it is very mild and generally does not affect work. Early lung function damage is not obvious, and late lung function may be impaired. When combined with lung infection, symptoms and signs tend to be obvious. The onset service age is mostly 7-23 years, with an average of about 20 years. X-ray chest radiographs: early irregular small shadows, mainly in the middle and lower lung area. There are small round-like shadows with wide distribution and low density; some are mainly small round-like shadows with high density, and large blocky shadows can be seen in late cases of individual cases. The hilum is generally not enlarged, and there are few pleural adhesions and emphysema. After leaving work, little progress was made.
???2. Harm of toxic gas Under the action of high temperature and strong ultraviolet rays generated by welding arc, a large amount of toxic gas, such as carbon monoxide and nitrogen oxide, will be generated around the arc area.
???(1). Ozone is a colorless, harmful gas with a special pungent odor, which has a strong stimulating effect on the respiratory tract mucosa and lungs. Short-term inhalation of low concentration (0.4mg / m3) of ozone can cause symptoms such as cough, dry throat, chest tightness, loss of appetite, fatigue, etc. Long-term inhalation of low concentration of ozone can cause bronchitis, emphysema, lung Hardening, etc.
???(2) Carbon monoxide is a colorless, odorless and non-irritating gas. It is easily combined with hemoglobin that transports oxygen in the human body and is very difficult to separate. Therefore, when a large amount of hemoglobin is combined with carbon monoxide, oxygen is lost The opportunity to combine with hemoglobin will make the body's function of transporting and using oxygen malfunction, causing human tissue to die due to lack of oxygen.
???(3) Nitrogen oxides are toxic gases with a pungent odor, and the nitrogen oxides that are often contacted are mainly nitrogen dioxide. It is a red-brown gas and has a special odor. When inhaled, it enters the alveoli through the upper respiratory tract and gradually interacts with water to form nitric acid and nitrous acid. .
???3. The hazards of arc radiation The arc generated by welding mainly includes infrared, visible and ultraviolet rays. Infrared rays can cause local skin temperature to rise, blood vessels dilate, erythema reaction, and repeated exposure to pigmentation. Short-wave infrared and visible light are converted into thermal energy by refractive interstitial focusing, resulting in visual choroid burns. The short-wave infrared rays can be absorbed by the cornea to produce thermal damage to the cornea, and can penetrate the cornea to damage the iris. If the working age is longer, the infrared light is absorbed by the iris pigment and converted into heat energy, which indirectly damages the crystal, or because the anterior segment tissues such as the cornea, iris, and crystal itself absorb infrared heat energy, the heat of the anterior segment increases, and the crystal protein undergoes hydrolytic deformation Solidification, leading to cataracts. The typical manifestation of infrared cataract is the vacuolar degeneration of the subcapsular cortex of the posterior pole, which is spider-like and gradually develops into a dish-like turbidity with clear boundaries. Early follow-up treatment of early infrared cataract workers can be surgically removed when the vision is seriously affected. Electromagnetic waves with a wavelength in the range of 100-400nm are called ultraviolet radiation, also known as ultraviolet rays. Ultraviolet rays can appear when the temperature of an object reaches 1200 ° C or higher. As the temperature increases, the wavelength of ultraviolet rays becomes shorter and the intensity becomes greater. Ultraviolet rays mainly harm the human body through photochemical action. It damages the eyes and bare skin, causing corneal conjunctivitis (electro-optic ophthalmitis) and skin erythema. The main manifestations are patients with eye pain, shame, tears, and redness and spasm of the eyelids. After ultraviolet irradiation, the skin may show obvious edema erythema, and in severe cases, blisters, exudate and puffiness may appear, and there is a significant burning sensation. Electro-optic ophthalmia is the most common type of electromagnetic radiation injury in ophthalmology. Its clinical manifestation is that the attack requires a certain incubation period. The length of the incubation period depends on the irradiation direction, radiation intensity and irradiation time. It is usually 6-8 hours, so it often occurs at night or early morning.
???2. Protection of occupational hazards in electric welding operations
???1. Improve the welding technology, improve the welding process and materials. By improving the welding technology, the welding operation can be mechanized, automated, and the people and the welding environment can be isolated. The harm of the electric welding operation to the human body is fundamentally eliminated. By improving the welding process, such as rationally designing the structure of the welding container, the new process of single-sided welding and double-sided molding is adopted to avoid the welder from welding in the poorly ventilated container, thereby greatly improving the working conditions of the welder; The soot ions are charged in situ to suppress the CO of the technology. The protection of the welding process can make 80% to 90% of the welding fumes on the working surface, realize the purification of the dust in situ, and reduce the pollution of welding fumes. Most of the harms caused by electric welding are related to the composition of the electrode coating. Therefore, by improving the electrode material, selecting non-toxic or low-toxic welding electrodes is also one of the effective measures to reduce welding hazards.
???2. Improve the ventilation situation of the workplace. Ventilation methods can be divided into natural ventilation and mechanical ventilation. Mechanical ventilation relies on the pressure generated by the fan to exchange air. The dust removal and detoxification effects are better. Therefore, in rooms with poor natural ventilation, closed When welding in the container, there must be mechanical ventilation measures.
???3. Strengthen personal protection measures Strengthen personal protection to prevent the harm of toxic gas and dust generated during welding. Workers must use corresponding protective glasses, face masks, masks, gloves, wear white protective clothing, insulated shoes, never wear short-sleeved clothes or roll up sleeves. If you work in a closed container with poor ventilation, you must wear Protective helmet for air supply performance.
???4. Strengthen labor protection publicity and education and on-site follow-up monitoring. Welding operators should be given the necessary occupational safety and health knowledge education to improve their self-prevention awareness and reduce the incidence of occupational diseases. At the same time, the monitoring of dust and poison hazards at the welding site and the physical examination of the welders should be strengthened to find and solve problems in a timely manner.