Welding production as a whole is based on the interatomic connection of the parts of the product being welded together. All production can be divided into three large classes: thermal, thermomechanical and mechanical. Classes differ in the ways of formation of interatomic bonds between products, energy sources, tools. Since welding works require less time and money, they are widely used in construction and industry. However, welding production is not safe for the health of the workers themselves and the people around them, therefore the topic of this article is labor protection in welding production.
General safety rules.
Only those workers who have passed a medical examination, introductory and primary instruction are allowed to work on welding of any kind. Each employee undergoes preliminary training and internship, only if there is a minimum electrical safety group (i.e. II), the employee can be admitted to self-fulfillment welding work.
When performing welding work, the worker is exposed to toxic substances that are contained in the welding aerosol and in the air. To prevent poisoning of the body, it is necessary to check the condition of the funds before starting work. personal protection, such as:
- tarpaulin gloves;
- canvas suit;
- boots made of genuine leather;
- goggles / visor / helmet with eye shield
- safety belt;
- respirator.
Cartridge respirator is used at high concentrations of dust and normal concentrations of gases. If the concentration of dust and gases exceeds the norm, if welding work is carried out in close quarters, workers are given respirators with increased filtration.
Safety rules before starting work.
Before starting work, the welder must check the tools and personal safety equipment, clear the workspace from debris, while not blocking the exit from the room or the passage to the street. It is necessary to prepare cold water in advance to cool the tool after work and check the presence of water in the water seal.
There must be no flammable objects within a radius of 5 m from the place of work.
Particular attention should be paid to gas cylinders: transport from place to place should be carried out only in trolleys designed for this purpose; in no case should the cylinder be lifted by the valve. If the balloon must be carried up stairs, the balloon should be carried at chest level, not overhead or on the shoulder. Before taking a cylinder, you must make sure that there is a plug on the valve fitting, and a cap on the cylinder itself.
If welding work takes place indoors, it is necessary to turn on the ventilation before starting the work itself.
In the event of a malfunction of the tools, this should be notified to the management, but in no case should you try to repair them yourself.
Safety rules directly during welding.
If work is carried out outdoors in rain or snow, the place of direct welding and within a radius of 5 m should be covered with a tarpaulin canopy.
If high-altitude work is carried out, it is necessary to build scaffolding. In no case should high-altitude welding work be carried out from ladders.
Before work, it is necessary to make sure that the edges of the parts to be welded are free of debris, dust and rust. If parts need to be cleaned, protective goggles must be worn. It is also necessary to check whether the parts to be connected are firmly attached. Parts to be cut must not fall down during operation.
All the rules listed above, which provide for labor protection in welding production, ensure not only safety, but also the convenience of the welder. Adhering to the safety rules and strictly following the instructions given in this manual is the key to correctly and safely performed welding work.
Dangerous and harmful production factors. Hazardous production factor is a factor, the impact of which on the welder can lead to injury.
A harmful production factor is a factor, the impact of which on a welder can lead to a disease.
The main dangerous and harmful production factors in manual arc welding coated electrodes are:
welding aerosols;
elevated level optical radiation in the ultraviolet, visible and infrared (thermal) ranges;
sparks, splashes and emissions of molten metal and slag;
increased temperature of the slag bath, materials, equipment and air in the working area;
high voltage in electrical circuit;
physical and neuropsychic overload.
A particularly characteristic harmful factor is the presence in the air of the working area of welding aerosols containing toxic substances. Their prolonged exposure to the body of a welder can lead to occupational diseases (pneumoconiosis, dust bronchitis, etc.).
The most harmful aerosols are formed during welding with highly alloyed electrodes containing nickel and chromium compounds. This must be taken into account when choosing means of neutralization. harmful substances in systems of industrial ventilation and personal respiratory protection of welders.
When using electrodes, you should be guided by the technical specifications, which contain requirements for safety and protection. environment with a list of harmful and dangerous factors, as well as protective equipment for welders and the environment.
When welding and cutting copper-zinc alloys and galvanized steels, zinc oxide is released, the effect of which on the body causes loss of appetite, thirst, increased fatigue and dry cough, which leads to bouts of fever (chills, fever, nausea, vomiting).
When welding and cutting lead and metal coated with lead paints, lead oxide is released, the effect of which on the body of the worker is manifested in the form of a metallic taste in the mouth, belching, loss of appetite and loss of strength. After 2.5–3.5 months, a lilac-gray border around the gums and severe headaches appear.
Manual arc welding is accompanied by radiation in the ultraviolet, visible and infrared ranges, which is many times higher than the value physiologically tolerated by a person. The radiation intensity of the welding arc and its spectral characteristics depend on the power of the arc, the welding method, and the type of welding materials.
An electric arc is a powerful source of bright light, ultraviolet, and infrared rays, the impact of which on unprotected eyes for 10–20 seconds within a radius of up to 1 m causes severe pain, tearing and photophobia.
The impact of an electric arc on the skin for 60–180 s causes a burn (similar to prolonged exposure to the sun), and prolonged exposure to the organs of vision leads to electrophthalmia and cataracts.
The intensity of infrared (thermal) radiation from the welded products and the weld pool is determined by the temperature of the products, their dimensions and design, as well as the temperature and dimensions of the weld pool. In the absence of personal protective equipment, exposure to thermal radiation exceeding allowable level, leads to violation of thermoregulation, heat stroke. Contact with hot metal can cause burns.
The intensity of electromagnetic fields depends on the design and power of the welding equipment, the configuration of the products to be welded. The nature of their influence on the body is determined by the level and duration of exposure. As a rule, in manual arc welding, the tension magnetic field insignificant (up to 300 A/m) and does not exceed the maximum permissible levels.
Sources of noise during arc welding are the welding arc, power sources, pneumatic actuators, etc. The noise level from the welding arc is determined by the stability of its combustion. Therefore, when welding with coated electrodes and other welding materials, which contain elements - arc stabilizers, the noise level does not exceed the permissible level.
Spattering of metal during welding is also a consequence of unstable arc burning. When using coated electrodes, it is negligible. Splashes, sparks and emissions of molten metal and slag in the absence of protective equipment can cause skin burns, eye injuries, and fires.
considered dangerous to human life electrical voltage over 42V AC and 110V direct current when working in welding shops and 12V - in damp rooms, closed metal volumes, etc. However, these stresses are conditional, since the danger of damage electric shock significantly depends on the individual characteristics of the organism and environmental conditions. The presence of even small amounts of alcohol in the blood dramatically reduces the electrical resistance of the human body. Wet or sweaty skin is much more electrically conductive than dry skin.
Static and dynamic physical loads during manual welding cause overstrain of the nervous and musculoskeletal systems of the body. Static loads depend on the mass of the welding tool (electrode holder, semi-automatic hose holder), flexibility of hoses and wires, duration continuous work and working posture (standing, sitting, half-sitting, kneeling, lying on your back). The greatest physical exertion is felt when performing welding work while half-sitting and standing when welding in a ceiling position or lying on your back in hard-to-reach places.
Dynamic overvoltage is associated with the performance of heavy auxiliary work: delivery to workplace workpieces, welding materials, lifting and carrying fixtures, turning the welded units. Such loads cause fatigue of welders and, as a result, a deterioration in the quality of welds.
In addition to these dangerous and harmful factors, during manual arc welding, the air of the working area is ionized with the formation of ions of both polarities. The reason for this is electrical and thermal ionization as a result of the electric arc process, as well as the effect of ultraviolet radiation from the arc on air. An increased or decreased concentration of negatively or positively charged ions in the air of the working area can also have an adverse effect on the health of workers.
General requirements. The electric welder must have a qualification group in electrical safety not lower than the second. A newly hired person, regardless of qualifications, is required to undergo an introductory safety briefing, as well as a briefing at the workplace, a preliminary medical examination, and subsequently, in the prescribed manner, undergo periodic medical examinations. Occupational safety briefings are carried out at least once every three months. When transferring to work using new equipment, the welder must familiarize himself with its design and undergo additional safety training.
The administration of enterprises and organizations is obliged to issue workers overalls, footwear and protective equipment that meet the standards or specifications in accordance with the issuance standards.
Before starting welding work, the electric welder is obliged to check the protective devices, helmet, shield, dielectric mat or dielectric boots, put on overalls - canvas suit with fire-resistant impregnation, boots, headgear, dielectric gloves or canvas mittens.
Insulating protective equipment is checked upon acceptance into operation, and then periodically at the following times: dielectric gloves once every 6 months, dielectric boots once every 3 years, dielectric boots, galoshes and tools with insulating handles once a year, dielectric mats once every 2 years.
All protective equipment, except for tools with insulating handles, must be stamped with the date of the next test and the highest rated voltage of the apparatus for which the protective equipment is intended.
To protect those working nearby, as well as auxiliary workers, from the radiant energy of welding arcs in permanent places welders for each electric welder arrange the cabin. The free area per one welding station in the cabin must be at least 3m2. The height of the cabin walls is 1.8–2m. For better ventilation walls are installed at a height of 50 mm from the floor, when welding in a shielding gas environment - at a height of 300 mm.
The temperature of the heated surface of the equipment must not exceed 45°C. The requirements for equipment used for manual arc welding with coated electrodes are set out in GOST 12.2.003, GOST 12.2.049, GOST 12.2.007.8, "Electrical Installation Rules", "Safety Rules for the Operation of Consumer Electrical Installations" and "Rules technical operation consumer settings.
Current sources must be reliably grounded (GOST 12.2.007.0). During operation, the voltage idle move power sources should not exceed 80V for AC and 100V DC. Power sources must be equipped with a voltmeter and a signal light indicating the presence or absence of voltage in the welding circuit, blocks for limiting idling.
Eye protection. In manual arc welding, the welding arc and molten metal can be a source of injury to the electric welder. Shields are designed to protect the welder from radiation and metal splashes, as well as from the effects of metal vapors, slag and aerosols released during welding. They are of two types: head and hand. The head shield is more comfortable as it frees the welder from having to hold it. Shields cover all exposed parts of the welder's head and neck. If necessary, it is not necessary to fold the shield back, it is enough to lift the cover of the frame with a light filter and inspect the structure through a transparent protective glass, prepare the joint for welding, clean the edges, remove slag and perform other operations.
To protect against harmful arc radiation, dark green glass filters are inserted into the shields, which allow you to see the arc, the melted metal and manipulate the electrode. 13 classes of type C light filters are used for welding current from 13 to 900A. (Table 2)
Table 2. Light filters for arc welding.
The most convenient are shields with automatic darkening of the light filter, freeing the welder's hands and excluding blind welding.
It must be borne in mind that the radiation of the welding arc can injure the eyes of people who are close to the welder. Therefore, workers present in the welding zone should be provided with glasses and filters. Arc radiation is dangerous for vision at a distance of up to 20m.
Cleaning of the metal surface is carried out in safety goggles with transparent safety glasses or protective shields.
Body protection. To protect the body from sparks and splashes of molten metal and slag, elevated temperatures materials and equipment, all-weather and summer overalls made of tarpaulin with heat-resistant, spark-resistant and fire-resistant impregnation are intended. Hands are protected with mittens (GOST 12.4.010).
Overalls (jackets and trousers) are made of a material that protects the welder from arc radiation. When working at stationary posts, the welder uses an apron that protects against metal splashes, especially dangerous when arc cutting. Shoes must have non-slip soles.
During work, the jacket must be buttoned up, cuffs tied or fastened, pockets closed with flaps, boots tightly laced, trousers should cover boots to prevent metal splashes on the legs. Overalls, footwear and gloves must be dry, without traces of oil.
Personal protective equipment also includes rubber mat, rubber gloves and galoshes used in especially dangerous work.
At welding work on outdoors in the cold season, overalls are supplemented with heat-protective linings in accordance with climatic zones.
Ventilation. Ventilation can be general and local. The general is made supply and exhaust. It serves to remove polluted air from the entire room and supply fresh air. General exhaust ventilation at permanent workplaces is not effective enough: the flow of polluted air, rising up from the arc or flame, adversely affects the electric welder. Therefore, the contaminated flow from the workplace is removed by local exhaust devices.
Effective local ventilation devices, deflecting the welding torch from the face of the worker and removing polluted air - exhaust panels. The choice of panel type depends on the volume of air to be removed, the length of the welding table and the dimensions of the workpieces to be welded. Exhaust panels are especially effective when welding relatively small parts. When welding on large sheets and structures, it is advisable to install local suction near the arc or panel mobile type connected to exhaust ventilation with telescopic pipes and swivel flanges.
Work in special hazardous conditions. For manual arc welding alternating current in especially dangerous conditions (inside a metal container, in the open air, as well as in a room with heightened danger) when changing electrodes, blocking devices are used. They allow you to change the electrodes when the voltage of the welding circuit is turned off or lowered to a safe value (12–14V). Perform work in canvas mittens. During breaks in welding, the electric holder is hung on a tripod or hook.
special attention requires the organization of the workplace when working inside tanks, boilers, wells and in other closed or cramped spaces, as this creates the risk of gas poisoning and electric shock.
An electric welder working in closed vessels is provided with a PSH-2 or PSH-1 gas mask, a life belt with a strong rope attached to it, rubber insulating mats on a felt or other lining that does not conduct heat well, a helmet made of dielectric material and overalls with rubber armrests and knee pads .
Before starting work in a hazardous area, take an air sample. During operation, the blower is fed into working area fresh air.
Containers to be welded, which were filled with oil products and other flammable and combustible liquids, must be washed and steamed
When performing welding work at height, the worker must have a safety belt and tool bag. If welders simultaneously work at different heights along the same vertical, means must be provided to protect people below from falling drops of molten metal and slag. A dense platform covered with sheets of roofing iron or asbestos is equipped under the welding site.
Welders working on construction sites are required to wear helmets that protect the head from falling objects, electric shock and weather. A balaclava is worn under the helmet.
Literature.
1. Vinogradov Yu.G., Orlov K.S. Material science for fitters. M. 1983
2 Kikhchik N.N. Rigging work in construction. M. 1983
3. Lupachev V.G. Manual arc welding. Mn. 2006
4. Tavastsherna R.I. Installation of technological pipelines. M.1980
5. Tavastsherna R.I., Besman A.I., Pozdnyshev V.S. Technological pipelines of industrial enterprises. Builder's Handbook. M. 1991
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The workplace of the welder must be kept clean and tidy, not allowing anything superfluous to interfere with work at the workplace, as well as in the aisles and driveways. Parts and blanks should be kept in a stable position on linings and racks, the height of the stacks should not exceed one and a half width or one and a half diameters of the base of the stack and in all cases should not be more than 1 m.
Welding cables must not be located near gas welding hoses and pipelines under pressure, or in areas with high temperatures, as well as near oxygen cylinders and acetylene generators.
Welding and cutting should not be carried out inside vessels with closed hatches or plugs that have not been turned out, near unprotected or unclosed hatches, openings, wells, etc.
Individual protection means
In electric arc manual welding, the welding zone (welding arc, molten metal) is a source of possible injury to the electric welder from the radiation and heat of the welding arc and splashes of molten metal. To protect the eyes, face, skin of the head and neck of the welder from radiation and metal splashes, as well as partial protection of the respiratory organs from direct exposure to metal fumes, slag and aerosols released during welding (small particles of molten metal and slag suspended in vapors), protective shields. Shields are made in two main types: head-mounted and hand-held. The head shield is more convenient, as it frees the welder's hand from having to hold the hand shield. Shields are made in a recessed shape so that they protect well all exposed parts of the head and neck of the welder. When using the shield to view the structure, it is not necessary to fold the shield back on the head, it is enough to lift the frame cover with a light filter and inspect the structure through a transparent protective glass, as well as prepare the joint for welding, clean the edges, remove slag and perform other operations that require good visibility. To protect against harmful arc radiation, glass filters are inserted into the shields. dark green, which do not transmit harmful radiation, but allow you to see the arc, molten metal and manipulate the electrode for better formation seam. 13 classes of type C light filters are used for welding at currents from 13 to 900 A. A variety of light filters allows the welder to choose the light filter suitable for her vision desired class. It must be borne in mind that the radiation of the welding arc can injure the eyes of workers in the vicinity of the working welder. Therefore, workers in the welding zone should be provided with goggles and filters intended for auxiliary workers. Arc radiation is dangerous for vision at a distance of up to 20 m.
Welders working on construction sites are required to wear helmets that protect the worker's head from possible injury from falling objects and protect against electric shock and weather impacts. Under the helmet should be worn headgear - balaclava. Important means of individual protection of the welder are overalls and safety shoes. Overalls (jackets and trousers) are made of material that protects the welder from radiation and has anti-spark stripes. For work in stationary posts, the welder uses an apron that protects against splashes, especially dangerous when arc cutting. The shoes of the welder working on the assembly site must have non-slip soles.
Personal protective equipment also includes a rubber mat, rubber gloves and overshoes used when working in a special dangerous places. During work, the welder must fasten the jacket, preventing exposure and damage by the rays of the arc to open areas of the body. The valves of the jacket must be closed, the trousers are worn to the release so that they cover the boots in order to avoid splashing metal on the legs.
When welding outdoors in the cold season, overalls should be equipped with heat-protective linings in accordance with climatic zones.
When using materials that emit an increased amount of welding aerosols (non-ferrous metals and steels with zinc and zinc coating, etc.), enhanced ventilation is used to provide clean air to the welder. general ventilation does not always achieve the desired effect, so they resort to personal protective equipment. For this, filtering dust respirators are mainly used and less often - insulating hose and self-contained breathing apparatus. effective method protection.
To reduce the concentration of harmful substances in the workplace to the maximum allowable, it is necessary to use suction of various types.
Local suction for manual electric welding
Manual electric welding of small products should be carried out in booths or fixed places equipped with local suction in the form of fixed lattice panels of uniform suction.
In the working section of the panel, the air speed is 0.15 m/s, which ensures air mobility in the welding zone at a distance of no more than 0.7 m from the suction of 0.5 m/s.
When welding under a layer of flux, a local suction is used, which is connected to a hose semiautomatic device.
When welding in carbon dioxide, local suction is used, combined with an automatic or semi-automatic torch.
When performing welding work, dangerous and harmful production factors arise that can lead to injury or occupational diseases.
HEALTH AND SAFETY DURING WELDING
Violation of safety regulations during welding often leads to the most unfortunate consequences - fires, explosions and, as a result, injuries and deaths.
The following injuries are also possible during welding - electric shock, burns from slag and metal drops, mechanical injuries.
To prevent all these provisions, it is important to strictly observe the precautionary measures.
1. Reliable insulation of all wires connected to the power supply of the current source and the welding arc, the device of geometrically closed switching devices, grounding of the bodies of welding machines. Grounding is subject to: cases of power supplies, equipment box, auxiliary electrical equipment. The cross section of the ground wires must be at least 25 mm2. Connection, disconnection and repair welding equipment only the electrician on duty is engaged. Welders are prohibited from performing these works /7/.
2. Application in power supplies of circuit breakers high voltage, which, at the moment of idling, break the welding circuit and supply a voltage of 12 V to the holder.
3. Reliable device of the electric holder with good insulation, which ensures that there will be no accidental contact of the current-carrying parts of the electric holder with the workpiece to be welded or the welder's hands (GOST 14651-69). The electrode holder must have high mechanical strength and withstand at least 8000 electrode clips.
4. Work in good dry overalls and gloves. When working in tight spaces and closed spaces it is mandatory to use rubber galoshes and rugs, light sources with a voltage of not more than 6-12 V.
5. When working on cathode-beam installations, the prevention of the danger of damage by hard X-ray rays (almost complete) absorption of harmful radiation associated with arc burning. The light beam of quantum generators (lasers) is especially dangerous in terms of damage to the eyes, since even reflected laser beams can cause severe damage to the eyes and skin. Therefore, lasers are automatic devices preventing such damage, but subject to strict observance production instructions operators-welders working on these installations /7/.
Protective glasses inserted into shields and masks are closed from the outside plain glass to protect them from splashes of molten metal. Shields are made of insulating metal - fiber, plywood, and in shape and size they must completely protect the face and head of the welder (GOST 1361-69).
To weaken the sharp contrast between the brightness of the arc and the low brightness of the dark walls (cabins), the latter should be painted in light colors (gray, blue, yellow) with the addition of zinc oxide to the paint in order to reduce the reflection of the ultraviolet rays of the arc falling on the walls.
When working outside the cabin, portable shields and screens /9/ should be used to protect the eyes of others, working welders and auxiliary workers.
Preventing the danger of splashing molten metal and slag. The molten metal splashes formed during arc welding have a temperature of up to 1800 degrees. C. in which clothing from any fabric is destroyed. To protect against such splashes, overalls (trousers, jacket and mittens) made of canvas or special fabric are usually used. Jackets during work should not be tucked into trousers, and shoes should have a smooth top so that splashes of molten metal do not get inside the clothes, as severe burns are possible in this case.
To protect against contact with wet, cold earth and snow, as well as with cold metal during outdoor work and indoors, welders must be provided with warm bedding, mats, knee pads and armrests made of fire-resistant materials with an elastic layer.
Poison prevention harmful gases and aerosols released during welding. Heat arc (6000-8000 ° C) inevitably leads to the fact that part of the welding wire, coatings, fluxes goes into a vapor state. These vapors, getting into the workshop atmosphere, condense and turn into a condensation aerosol, the particles of which are close to smoke in terms of dispersion and easily enter the respiratory system of welders. These aerosols represent the main occupational hazard for welders. The amount of dust in the welder's breathing zone depends mainly on the welding method and materials being welded, but to a certain extent it is also determined by the type of structures. Chemical composition electric welding dust depends on the welding methods and the types of base and welding materials.
There are strict requirements in the field of ventilation during welding work. To capture welding aerosol at stationary posts, and where possible, also at non-stationary ones, it is necessary to install local exhausts in the form of a fume hood of a vertical or inclined panel of uniform suction of a table with under-grid exhaust, etc. When welding large-sized serial structures on conductors, manipulators, etc. • local suctions must be built directly into these devices. At automatic welding submerged arc, in shielding gases, electroslag welding, devices with local exhaust gases are used.
When using cylinders with compressed gases, it is necessary to observe the established safety measures: do not drop cylinders, do not install them near heating devices, do not store oxygen and combustible gas cylinders together, store cylinders in an upright position. When moisture freezes in the reducer of a CO2 cylinder, warm it up only through a special electric heater or by wrapping it with rags soaked in hot water. It is strictly forbidden to warm any cylinders with compressed gases with an open flame, as this almost inevitably leads to an explosion of the cylinder.
When performing welding work on previously used containers, it is required to determine the type of product stored and the presence of its residues. It is obligatory to thoroughly clean the vessel from product residues and 2-3 times washing with a 10% alkali solution; subsequent purging is also necessary. compressed air to remove odors that may be harmful to the welder /3/.
It is strictly forbidden to blow the containers with oxygen, which is sometimes attempted, since in this case the ingress of oxygen on the clothes and skin of the welder with any open source of fire causes intense ignition of the clothes and leads to fatal burns.
An explosion hazard also exists when performing work in rooms with a large number of pulverized organic substances (food flour, peat, coal). This dust at a certain concentration can give explosions. great strength. In addition to thorough ventilation, welding in such rooms requires special permission fire department.
Fire prevention from molten metal and slag. The risk of fires for this reason exists when welding is performed on metal covering wood or combustible insulating materials, on wooden scaffolding, near flammable materials, etc. All of these welding options should not be allowed.
Prevention of injuries associated with assembly and transport operations (mechanical injuries). It is important to introduce integrated mechanization and automation, which significantly reduces the risk of injuries of this kind.
The main causes of injuries during assembly and welding: lack of Vehicle for transportation of heavy details and products; vehicle malfunction; malfunction of rigging devices; faulty tools: sledgehammers, hammers, wrenches, chisels, lack of goggles when cleaning seams from slag; lack of overalls and other protective equipment.
Security measures in this case: all specified means and tools should be checked periodically; rigging work must be carried out by persons who have undergone special instruction; workers must be required to comply with all safety regulations, including work in overalls, gloves; use of means of individual ventilation (where necessary), etc. The introduction of complex mechanization and automation is of great importance, which significantly reduces the risk of injuries of this kind.
To make it convenient for welders to work, the following recommendations should be observed:
1. Assembly and welding of large sections should be carried out on specialized places, beds, stands, while sufficient passages should be provided on each side of the structure.
2. When welding volumetric sections at a height, it is necessary to arrange scaffolding with the location of welding equipment outside the workplace of the welder.
3. All equipment that may be energized in a faulty condition must be individually grounded with a lead to a common protective ground.
4. All welding installations must be supervised by a fitter. Only the fitter-adjuster has the right to correct defects in electric welding equipment.
