Noise
The noise in welding workshops is mainly generated by the aerodynamic noise during plasma spraying and cutting processes. Its intensity depends on various factors, such as gas flow rate, gas properties, site conditions, and the diameter of the welding gun nozzle. Most of this type of noise exceeds 100dB.
High Frequency Electromagnetic Radiation
High frequency electromagnetic radiation is produced with the increasing application of argon arc welding and plasma welding. When plasma welding and argon arc welding use high frequency oscillators for arc ignition, the oscillator generates strong high frequency oscillations, which breakdown the air gap between the thorium-tungsten electrode and the nozzle and ignite the plasma arc.
Additionally, a portion of the energy is radiated into space in the form of electromagnetic waves, forming a high frequency electromagnetic field, which pollutes the local environment.
The intensity of high frequency electromagnetic radiation depends on the output power of the high frequency equipment, the working frequency of the high frequency equipment, the distance of the high frequency oscillator, and whether the equipment and transmission line are shielded.
Optical Radiation
In various welding processes, especially in various open arc welding, poorly protected submerged arc welding, and slag making stage of electric arc welding, exposed arcs are generated, forming optical radiation.
The intensity of optical radiation depends on the following factors: welding process parameters, welding methods, distance and relative position to the welding point, and protective measures.
Harmful Effects of Welding Workshop Pollution on Operators
The occurrence of welding occupational diseases is the result of the comprehensive effect of various welding pollution factors. Occupational diseases of welders include welder’s pneumoconiosis, manganese poisoning, fluoride poisoning, metal fume fever, and arc eye.
Among them, the medical clinical manifestations of chemical pollution (welding fumes and harmful gases) are cough, sputum, chest tightness, shortness of breath, and sometimes hemoptysis. The medical clinical manifestations of physical pollution are diverse.
Noise can cause operators to feel irritable and have headaches; the main effect of high-frequency electromagnetic radiation on the human body is a comprehensive syndrome of neurasthenia, such as dizziness, headaches, fatigue, palpitations, emaciation, and hair loss; during the welding process, light radiation can cause arc eye, with mild discomfort and foreign body sensation in the eyes, and severe burning and pain in the eyes.
The occurrence of welding occupational diseases mainly depends on the following factors: the concentration, nature, and degree of pollution of welding fumes and gases, the frequency and duration of welders’ exposure to harmful pollution, the individual physical fitness and personal protective conditions of welders, the quality of the production environment in which welders are located, and the interaction of various harmful factors.
Only when welders work in poor working conditions or lack labor protection for a long time is there a possibility of occupational diseases occurring.
Prevention, control, and development direction of pollution in welding workshops.
The three approaches to preventing pollution in welding workshops are source control, transmission pathway management, and personal protection.
Source Control
The types and quantity of pollutants generated during welding depend on the production process, equipment, and technical capabilities of operators.
Optimization of Production Process Selection
Different welding processes produce significantly different types and quantities of pollutants. When conditions permit, mature hidden-arc welding should be used instead of visible arc welding to greatly reduce the degree of pollution.
Equipment Improvement
Under the premise of determining the production process, equipment with high mechanization and automation levels should be selected. Low-dust and low-toxic welding rods should be used to reduce smoke concentration and toxicity. When purchasing new equipment, attention should be paid to its environmental performance, and integrated equipment with purification components should be used as much as possible.
Improvement of Operator Technical Level
High-level welders can skillfully and flexibly follow operating rules during the welding process, such as constantly observing the drying degree, tilt angle, length, and position of the welding rod and making corresponding technical adjustments. Compared with unskilled workers, dust emissions can be reduced by more than 20%, welding speed can be increased by 10%, and welding quality can be improved.
Transmission Pathway Management
Control of Welding Smoke and Harmful Gases
There are two ways to control welding smoke and harmful gases in transmission pathways: comprehensive ventilation and local exhaust.
Comprehensive ventilation, also known as dilution ventilation, uses clean air to dilute the concentration of harmful substances in the indoor air to prevent it from exceeding the highest allowable concentration specified by hygiene standards. The polluted air is continuously discharged outside or collected and purified.
Comprehensive ventilation includes two methods: natural ventilation and mechanical ventilation. In foreign countries, natural ventilation is generally used for outdoor welding or welding in open spaces, while mechanical ventilation is usually used for indoor operations.
Axial flow fans installed on walls or ceilings are used to exhaust welding smoke from the workshop outside or to recycle purified air inside the workshop, thereby reducing the concentration of smoke in the workshop. Recycling purified air solves the problem of energy loss in the workshop and is widely used in foreign countries.
Local exhaust is the treatment of local airflow to prevent the pollution of harmful substances and maintain a good air environment in the working area. Local exhaust systems generally consist of gas-collecting hoods, air ducts, purification systems, and fans.
Depending on the collection method, local exhaust can be divided into fixed and mobile systems. Fixed local exhaust systems are mainly used in large welding production workshops where the working locations and methods of workers are fixed, and the position of the hoods can be fixed according to actual conditions.
The working status of mobile local exhaust systems is relatively flexible, and different working postures can be adopted according to different working conditions to ensure processing efficiency and operator convenience.
Purification systems for welding smoke and harmful gases usually use a combination of bag filters or electrostatic precipitators and adsorbents, with high processing efficiency and stable working status.
Noise Control
The noise in welding workshops is mainly reflected sound. Therefore, sound-absorbing materials should be placed on the walls of the workshop when conditions permit. Placing sound-absorbing material in space can reduce noise by about 30 dB.
High-frequency Electromagnetic Radiation Control
The workpiece should be well grounded during welding. At the same time, ventilation and cooling should be strengthened to control the temperature and humidity of the workplace.
Control of Optical Radiation
Protective screens should be installed in welding workstations, and the protective screens should be gray or black, and the workshop walls should be decorated with absorbent materials. Both measures can reduce arc reflection and protect the operator’s eye health.
Personal Protection
In some specific places, such as underwater, high altitude, tanks, or ship compartments, overall protection is difficult to achieve due to the limitations of the location.
In such cases, personal protective equipment becomes the main protection measure. Personal protective equipment is designed according to the characteristics of various hazardous factors, with strong pertinence and a variety of types, such as face shields, helmets, protective goggles, safety helmets, earplugs, masks, etc.
Welding Safety, Hazards, and Prevention
- Incidents of combustion and explosion caused by welding sparks
- Accidents of burns and scalds caused by welding flames or torches
- Electrical shock accidents and falling accidents at high altitudes that occur during welding
- Welders can cause blood, eye, skin, and lung diseases during operations
- Welders are often exposed to radiation hazards such as bright light, infrared radiation, and ultraviolet radiation during welding. The X-rays produced by electron beams during welding can also affect the welder’s physical health
- Toxic fumes in the form of smoke and vapor are formed by the evaporation or combustion of the welding area, welding rods, dirt, paint, etc. due to high temperatures during welding
- High-frequency electromagnetic fields generated during welding can cause dizziness and fatigue The hazards of welding operations are not unavoidable. As long as each welder strictly complies with the welding safety regulations during the operation, these hazards can be prevented. Safety Precautions for Welding and Cutting Torches
- Before using the welding torch, check its absorption performance and airtightness. The various connecting parts of the welding torch, gas passages, and regulators should not be greasy.
- When igniting the welding torch, turn on the acetylene valve first and then ignite it. Then, turn on the oxygen valve to adjust the flame. When turning off the torch, turn off the acetylene first and then the oxygen. It is strictly prohibited to make permanent connections between the welding torch, hose, and gas source when not in use.
- When using the cutting torch, clean the paint, rust, etc. on the working surface, and do not work on cement floors to prevent rust water and cement from splashing and hurting people at high temperatures.
- When igniting the cutting torch, conduct an ignition test first to check whether the cutting nozzle is properly installed. When turning off the torch, turn off the acetylene first and then the oxygen.
Conclusion
There are many types of pollution in welding workshops, and comprehensive management should be carried out from three aspects: pollution sources, transmission pathways, and personal protection.
Pollution control measures should be based on the specific situation of workshop stations and should not be disconnected from actual production operations. The design of pollution control measures should fully consider the treatment effect of various pollution control methods and use integrated equipment and facilities to reduce site occupation and investment.
Potential hazards in metal welding operations include electric shock, arc radiation, welding smoke, fire, and explosion. Metal welding is widespread in the construction operations of the petrochemical industry, so it is essential to pay attention to the harm that metal welding can cause to human health.
Based on the characteristics of safety management in welding operations at home and abroad and practical management experience in petrochemical construction enterprises, effective protection measures for potential hazards in metal welding operations can be analyzed and proposed from the following aspects.
Radiation hazards that welders often face in welding operations include strong light, infrared radiation, and ultraviolet radiation. The X-rays generated by the electronic beam during welding can also affect the welder’s health.
