Dangers and hazards when welding aluminum. What harmful substances are formed during welding? Measures to reduce the risk of disease

Prevents intense burnout of alloying elements, however, toxic compounds of manganese, chromium, titanium, tungsten, cobalt, etc. get into the air.

The emission of dust at the most is small. Its highest concentrations (up to 8 mg/m3) are observed at a distance of 200 mm from the arc. The composition of the welding aerosol when welding low-carbon and low-alloy steels includes:

• iron oxides (up to 80%);
• manganese (up to 12%)
• silicon dioxide (8%).

The concentration of manganese oxides (in terms of manganese) - 0.4 mg / m 3, silicon oxide - up to 1.6 mg / m 3.

Of the harmful gases released during submerged arc welding (SAW), the most dangerous are carbon monoxide and fluorine compounds - hydrogen fluoride and silicon fluoride. The concentration of carbon monoxide when using ceramic fluxes (without ventilation) reaches 400 mg / m 3, hydrogen fluoride - up to 1.7 mg / m 3. The largest number fluorine compounds are released when welding under flux OSC-45 (up to 360 mg/kg) and AN-348A (up to 160 mg/kg), and the least - when using fluxes FTs-9 (up to 65 mg/kg) and AN-51, AN-10 (up to 85 mg/kg). In addition, the release of fluorine compounds is significantly affected by technological conditions (, electrode diameter, current strength, etc.). So, with an increase in the welding speed, the amount of fluoride compounds released decreases, the same happens with an increase in the diameter of the electrode (electrode). However, in order to radically improve working conditions the use of fluxes containing fluorine compounds should be abandoned replacing them with less harmful ones.

Dust content in the breathing zone during the normal course of the process and sufficient qualification of the welder does not exceed the MPC. However, the suction and collection of the flux, refilling for its reuse are additional sources of dust emission.

The dust concentration in the welder's breathing zone during flux collection is on average 30 mg/m 3, which exceeds the MPC. It has been established that when the flux is reused, the dust content of the air is 2 times higher than when welding under fresh flux. With the repeated use of the flux, a breakthrough of gases and dust is sometimes observed at the place of the arc, which increases the amount of harmful substances released several times. In addition, one should keep in mind the common factor for all types of welding, the increase in dust emissions during process intensification (working at high currents) due to the entrainment of fine particles by convective flows. To combat dust formation during flux collection, it is desirable to use pneumatic ejector flux collectors equipped with a filter.

It should also be added to the features of submerged arc welding that a worker observing the welding process at a certain distance from the arc is less exposed to harmful substances even in the absence of local suction.

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As you know, welding processes are characterized by intense heat release (radiant and convective), dust emission, leading to high dust content. industrial premises toxic fine dust, and gas emissions that have a negative effect on the body of workers. Some processes, such as plasma-arc cutting, are accompanied, in addition, by intense noise, which also creates unfavorable working conditions.

The high temperature of the welding arc promotes intense oxidation and evaporation of the metal, flux, shielding gas, and alloying elements. Oxidized by atmospheric oxygen, these vapors form fine dust, and the convective flows that occur during welding and thermal cutting carry gases and dust upwards, leading to high dust and gas contamination of industrial premises. Welding dust is finely dispersed, the speed of its particles is no more than 0.08 m / s, it settles slightly, therefore its distribution along the height of the room is in most cases even, which makes it extremely difficult to combat it.

The main components of dust during welding and cutting of steels are oxides of iron, manganese and silicon (about 41, 18 and 6%, respectively). The dust may contain other compounds of alloying elements. Toxic inclusions that are part of the welding aerosol, and harmful gases, when they enter the human body through the respiratory tract, can have an adverse effect on it and cause a number of occupational diseases. Fine dust particles (from 2 to 5 microns), penetrating deep into the respiratory tract, pose the greatest health hazard, dust particles up to 10 microns in size and more linger in the bronchi, also causing their diseases.

The most harmful dust emissions include manganese oxides, which cause organic diseases of the nervous system, lungs, liver and blood; silicon compounds, causing their silicosis as a result of inhalation; chromium compounds that can accumulate in the body, causing headaches, diseases of the digestive organs, anemia; titanium oxide, which causes lung disease. In addition, compounds of aluminum, tungsten, iron, vanadium, zinc, copper, nickel and other elements adversely affect the body.

The biological properties of electric welding dust are fully and well described in the work of K. V. Migai, in which three main hygienic indicators of the harmfulness of dust are analyzed: solubility, breath holding by the lung tissue and phagocytosis. Many of the studies (for example, the solubility of electric welding dust in the body) are of great practical value in assessing the aggressiveness of the welding aerosol.

Harmful gaseous substances entering the body through the respiratory tract and digestive tract sometimes cause severe damage to the entire body. The most harmful gases released during welding and cutting are nitrogen oxides (especially nitrogen dioxide), which cause diseases of the lungs and circulatory organs; carbon monoxide (suffocating gas) - a colorless gas, has a sour taste and smell; being 1.5 times heavier than air, it goes down from the breathing zone, however, accumulating in the room, it displaces oxygen and, at a concentration of more than 1%, leads to irritation of the respiratory tract, causes loss of consciousness, shortness of breath, convulsions and damage to the nervous system; ozone, the smell of which in high concentrations resembles the smell of chlorine, is formed during welding in inert gases, quickly causes eye irritation, dry mouth and chest pain; Hydrogen fluoride is a colorless gas with a pungent odor that acts on the respiratory tract and even in small concentrations causes irritation of the mucous membranes.

When welding in a shielding gas environment with thoriated tungsten electrodes of the VT-10, VT-15 grades, thorium oxides and its decay products are released into the air, which pose a radiation hazard.

Detailed information about the harmful effects on the body of various elements and compounds is given in the special literature.

In addition to aerosols and gases, a number of other phenomena that are not eliminated by ventilation, but in combination with harmful substances worsen working conditions, have an adverse effect on workers in welding industries. These are the radiant energy of the welding arc, ultraviolet and infrared radiation, which cause burns to exposed parts of the body and sometimes (especially in summer) overheating of the body; noise, which, in combination with ultrasonic vibrations, causes permanent hearing loss in workers. In addition to the noise generated by welding, procurement operations (straightening, straightening, assembly) and especially plasma-arc cutting are accompanied by a lot of noise Create noise and poorly balanced ventilation units(or mounted without vibration bases).

As you can see, there are many reasons for occupational diseases of welders, gas cutters and other workers in welding industries. Knowledge of the main types of welding and cutting contributes to the successful struggle for the creation of favorable working conditions, the required air purity in the working area through the development of rational and efficient systems of local and general ventilation, the use of personal protective equipment for eyes, hands, etc. Practice shows that ventilation in together with a set of measures of a technological and organizational nature, it allows to reduce the concentration of harmful substances to the maximum permissible and contributes to a significant improvement in the working conditions of workers in welding shops.

V.L. Pisarenko, M.L. Roginsky. "Ventilation of workplaces in welding production", Moscow, Mashinostroenie, 1981

The electric arc is a powerful source of radiation of ultraviolet, infrared and visible rays.

Ultraviolet radiation is the most dangerous to the eyes, as it causes temporary damage to the eyes (welding flash). There may be a sharp pain in the eyes, photophobia, inflammation of the mucous membrane of the eyes. Ultraviolet radiation can also damage the skin, as in sunburn.

Infrared radiation bears thermal energy, which can cause reddening of the skin and burns of varying degrees, damage to the retina and lens.

Visible radiation has a blinding effect and a harmful effect on vision.

The best protection against all types of radiation are Chameleon welding helmets with self-darkening cartridges. For example, the Yincheng welder's mask protects the worker from UV and IR radiation.

Gases during the welding arc are released in the form of smoke and welding aerosols containing compounds of manganese, silicon, chromium, nitrogen, fluorine, titanium and other compounds.

Manganese oxides are formed when welding steels containing manganese, or when welding with electrodes containing manganese. Such oxides enter the body through the respiratory and digestive organs and can cause acute and chronic poisoning, affecting nervous system. They also act on the lungs and liver.

Symptoms:

• headache,
• dizziness,
• heartburn,
• pain in the limbs.

Silica in aerosols of the welding arc appears in the presence of silicon compounds in the electrode coatings. Silicon dioxide causes lung disease - silicosis.

• cough,
• labored breathing,
• nausea.

Chromium oxides formed during welding of steels containing chromium. They enter the body through the respiratory system and irritate the nasal mucosa, causing a runny nose and easy bleeding. At high concentrations of these oxides, damage to the nose is possible, up to perforation of the cartilaginous part of the nasal septum.

• headaches,
• weakness inflammatory processes in the gastric tract.

and vapors are formed when welding copper-zinc alloys, galvanized and zinc-painted parts.

• poor appetite,
• sweetish taste in the mouth
• elevated body temperature.

Hydrogen fluoride may be released from electrode coatings during welding and irritate the upper respiratory tract.

• sneezing,
• runny nose,
• nose bleed,
• loss of smell.

Nitrogen oxides- are formed when the welding arc comes into contact with the surrounding air. Once in the respiratory system, they come into contact with their wet surface, forming nitric acid, which affects the lungs.

Symptoms:

• cough,
• headache,
• loss of consciousness.

During welding, intense splashing of molten metal and slag occurs, their splashes can cause burns to the body. Chameleon masks quite reliably protect the eyes from harmful radiation, and the concept can refer not only to welding, but also, for example, to a chameleon mug with application, which you can make to order in high quality at affordable prices in Moscow.

At welding work, during grinding and related technologies, harmful substances are formed during chemical and physical processes
in the form of gaseous and solids from materials, filler materials and contaminants.

The occurrence of gaseous and solid particles during welding and related processes depends on the technology used and the type of base material, (gaseous harmful substances arise primarily as a product of the reaction of process gases and gases from the surrounding atmosphere.
Substances in the form of solid particles are formed primarily from filler materials used for welding.

Particles
The chemical composition of particles in welding operations primarily depends on the type of filler materials used. In the thermal cutting of metals, dust particles are formed during the production process of the material being cut. The number of particles depends on the combination of technologies used, materials and the capacity of a given production technology.

Factors affecting the amount and type of harmful substances
- electric current, voltage
- shell type
- type of electric current
- electrode installation angle
- electrode diameter
- welding method
Depending on the technology used - manual arc welding, thermal cutting with oxygen, plasma and laser - particles of different sizes with different morphologies are formed.
Exposure to health-damaging particles primarily depends on particle size (particle diameter).
During various welding processes, smoke is generated during welding with various particles, the diameter of which, however, varies from 0.1 µm to 1.0 µm, mostly even within the range of less than 0.4 µm.

These ultra-light particles have the ability to penetrate into the lung alveoli. This means that they penetrate into the smallest pulmonary vesicles (alveoli), and there they are deposited. From the pulmonary vesicles, they penetrate into the circulatory system, diffuse through the walls of blood vessels and are deposited in the human body.

Only the development of new measurement methods in recent times has made it possible to determine the size and quantity of dust particles that form harmful substances in the ultrafine fraction.

The fumes that arise during the welding process clearly have the ability to penetrate into the alveoli

The table says that 98.9% of the particles are within 0.4 microns.
Particles larger than 1.0 µm are very rare.

About particle size in detail

Manual arc welding
In manual arc welding with a sheathed rod electrode, for the most part, particles are formed in the range from 0.01 µm to 0.4 µm.

Arc welding in a protective atmosphere
Only a small number of particles produced during shielded arc welding have a value greater than 0.2 µm. The value of the maximum fraction of particles is in the range from 0.01 µm to 0.05 µm.
And when welding high-alloy steels in a protective atmosphere, the particle size is mainly 0.01 microns. The agglomerated particles reach sizes up to 0.5 µm.

MIG welding
When welding aluminum alloys using the MIG method, the particles of combustion products formed during the welding process, almost without exception, are characterized by a value of less than 0.4 microns. And here the main fraction of particles ranges from 0.01 µm to 0.05 µm.

Thermal cutting of metals
During thermal cutting - cutting with oxygen, plasma, laser - particles arise as a result of release from the materials being cut. The particles have a diameter of 0.03 µm. In agglomerated form, secondary particles up to 10 µm in diameter can be formed.

Harmful substances in the form of gaseous particles
The greatest risk of harm to health is caused by harmful substances in the form of solid particles. But with various technologies, harmful substances in the form of gaseous particles also arise, first of all, these include:

- carbon monoxide
- nitric oxide
- nitrogen dioxide
- ozone

Carbon monoxide
Carbon monoxide (CO) is a gas that is poisonous. Formed in critical concentrations during MAG welding in a carbon dioxide protective atmosphere or during MAG welding in a mixed gas protective atmosphere with a high proportion of carbon dioxide.

Nitric oxide and nitrogen dioxide
Nitric oxide and nitrogen dioxide (NOX = NO, N02) is a gas that is poisonous. Occurs with technologies carried out by autogenous technology, with plasma cutting with compressed gas or nitrogen, and with laser cutting with compressed gas or nitrogen.
Nitrogen dioxide is already dangerous at relatively low concentrations, and at high concentrations it can lead to fatal pulmonary edema.

Ozone
Ozone (03) is a gaseous substance and is formed primarily during welding work in a protective atmosphere from highly reflective materials. Ozone is a very unstable gas. The presence of other dust harmful substances in the air can cause the decomposition of ozone into oxygen.

Generalization.
The maximum danger for the welder and maintenance personnel of cutting equipment, laser cutting devices, etc. represent ultrafine particles up to 0.4 microns.
These particles penetrate into the alveoli and, further, through the circulatory system enter the human body, where they are deposited.
Sooner or later, these precipitations can cause severe damage to health, which can lead to cancer.