The main occupational hazards of special welding operations are dust, toxic gas, high temperature, arc light and high frequency electromagnetic field. Today, with the rapid development of social economy, welding operations involve almost all industrial fields, the number of welders has risen sharply, and the occupational hazards in welding have become increasingly prominent.
First, the main hazards in welding operations
1. Harm of metal dust
The composition of welding fume changes with the use of covered electrode. Covered electrode consists of welding core and coating. The core contains a lot of iron, carbon, manganese, silicon, chromium, nickel, sulfur and phosphorus. The materials in the coating are mainly composed of marble, fluorite, rutile, pure salt, water glass, ferromanganese and so on. During welding, the high temperature of 4000℃-6000℃ is generated by arc discharge. When covered electrode and weldments are melted, a lot of smoke and dust will be produced, which is mainly composed of iron oxide, manganese oxide, silicon dioxide, silicate and so on. Smoke particles diffuse in the working environment and are easily inhaled into the lungs. Long-term inhalation can cause pulmonary fibrosis, which is called welder's pneumoconiosis, often accompanied by manganese poisoning, fluorosis and metal smog fever. The main manifestations of patients are chest tightness, chest pain, shortness of breath, cough and other respiratory symptoms, accompanied by headaches, general weakness and other diseases, and lung function is also damaged to some extent.
2. Hazards of toxic gases
Under the action of high temperature and strong ultraviolet rays generated by welding arc, a large number of toxic gases such as carbon monoxide and nitrogen oxides will be produced around the arc area.
(1) ozone is a colorless and harmful gas with a special pungent smell, which has a strong stimulating effect on respiratory mucosa and lungs. Inhalation of ozone with low concentration (0.4 mg/m3) for a short time can cause symptoms such as cough, dry throat, chest tightness, loss of appetite and fatigue, while inhalation of ozone with low concentration for a long time can cause bronchitis, emphysema and pulmonary sclerosis.
(2) Carbon monoxide is a colorless, odorless and non-irritating gas, which is easily combined with hemoglobin which transports oxygen in human body and is extremely difficult to separate. Therefore, when a large amount of hemoglobin is combined with carbon monoxide, oxygen loses the opportunity to combine with hemoglobin, which hinders the function of transporting and utilizing oxygen, leading to the necrosis of human tissues due to lack of oxygen.
(3) Nitrogen oxides are toxic gases with pungent odor, among which nitrogen oxides that are often contacted are mainly nitrogen dioxide. It is a reddish-brown gas with a special smell. After inhalation, it enters the alveoli through the upper respiratory tract and gradually reacts with water to generate nitric acid and nitrous acid, which strongly stimulates and corrodes lung tissue and causes pulmonary edema.
3. The harm of arc radiation
The arc produced by welding mainly includes infrared, visible and ultraviolet rays. Among them, the harm of ultraviolet rays to human body is mainly through photochemical action, which damages eyes and bare skin, causing corneal conjunctivitis (electro-optic ophthalmia) and skin erythema. The main manifestations are eye pain, shame, tears, eyelid swelling and spasm. After the skin is irradiated by ultraviolet rays, edema and erythema with obvious boundaries may appear, and in severe cases, blisters, exudates and edema may appear, with obvious burning sensation.
Second, the protection of occupational hazards in welding operations
To sum up, there are many harmful factors in welding operation, all of which are harmful. Therefore, in order to reduce the occupational hazards of welders, a series of effective preventive measures must be taken.
1. Improve welding technology and materials.
By improving the welding technology, the welding operation is mechanized and automated, and people are isolated from the welding environment, thus fundamentally eliminating the harm of welding operation to human body. By improving the welding process, such as reasonably designing the structure of the welding container and adopting a new process of single-sided welding and double-sided molding, the welder can be prevented from welding in a poorly ventilated container, and the working conditions of the welder are greatly improved. Another example is that ion with welding fume are char in situ.
Suppression technology company. Protective welding technology can restrain 80% ~ 90% of welding dust in working face, realize on-site dust purification and reduce welding dust pollution. Since the welding hazards are mostly related to the composition of covered electrode coating, it is also one of the effective measures to reduce the welding hazards by improving covered electrode materials and choosing non-toxic or low-toxic covered electrode.
2. Improve the ventilation in the workplace.
Ventilation methods can be divided into natural ventilation and mechanical ventilation, in which mechanical ventilation relies on the pressure generated by the fan to exchange air, and the effect of dust removal and detoxification is better. Therefore, mechanical ventilation measures must be taken when welding in a closed container with poor natural ventilation.
3. Strengthen personal protective measures
Strengthening personal protection can prevent the harm of toxic gas and dust produced during welding. Operators must use corresponding protective glasses, masks, masks and gloves, wear white protective clothing and insulated shoes, and are not allowed to wear short sleeves or roll up sleeves. If they work in a closed container with poor ventilation, they must also wear a protective helmet with gas supply performance.
4. Strengthen labor protection publicity and education and on-site tracking and monitoring.
Necessary occupational safety and health education should be given to welding workers to improve their self-prevention awareness and reduce the occurrence of occupational diseases. At the same time, we should also strengthen the monitoring of dust and toxic hazards in welding workplaces and the physical examination of welders to find and solve problems in time.