11. Occupational safety requirements when repairing tank boilers

Before being delivered to the depot, tanks must be cleaned, steamed and degassed at PPP.

Before starting work on the tank boiler, the air environment should be re-analyzed with a gas analyzer under the guidance of the deputy depot manager or foreman.

Before starting work on the tank boiler, the mechanic must check the availability of a certificate of form VU-19 on the suitability of the tank for repair, indicating the type of treatment, analysis results, signatures of the persons and the seal of the organization that carried out this work. In the absence of such an act, repair work on the tank is not allowed.

When working inside the tank boiler, it is necessary to open the cap cover and the drain valve, provide fresh ventilation with sufficient air exchange, and in cases where ventilation does not provide the required air frequency of the working area, respiratory protective equipment should be used (hose breathing device or hose gas mask) providing clean air supply to the breathing zone. In the cold season, the supplied air must be heated to 18-200C.

Workers should descend into the tank boiler for repairs using ladders located inside the boiler. In the absence of permanent ladders, portable wooden unframed ladders must be used, the length of which must be at least 3.3 m.

Work on top of the tank boiler must be carried out from mobile platforms or at a special workplace equipped with a cable for attaching a safety belt.

Work related to lowering the tank into the boiler must be performed by two mechanics.

Before lowering the tank into the boiler, the mechanic must put on a safety belt with a safety rope attached to it. The second end of the rope must be in the hands of the supervising mechanic, who must, when performing work inside the boiler, be constantly at the tank cap and be able to give and receive signals using the rope, and also, if necessary, provide assistance to the mechanic located inside the boiler.

Simultaneous work on the outside and inside of the tank boiler is prohibited.

To communicate between mechanics using a safety rope, the following alarm system is installed:

One jerk from below (from the boiler) - “tighten the hose and rope”, and they need to be tightened after repeating the signal of the observing worker located at the boiler hatch and receiving the same response signal from the boiler;

Two jerks in a row - “let go of the hose and rope.” This signal is given by the mechanic working in the boiler to allow movement inside the boiler;

Two jerks with breaks between them - “release the container” or “raise the container” (depending on where it is at the moment);

Repeated tugs given by the observing worker located at the boiler hatch, the mechanic in the boiler is obliged to go to the hatch or go upstairs. The same signal given by a mechanic working in a boiler means a requirement to immediately take measures to remove it from the boiler.

If there is no response to the rope pulls given by the observing worker located at the boiler hatch, he must raise the alarm and call the foreman, other workers and a medical worker to provide assistance to the victim.

Welding work inside tank boilers must be carried out in accordance with the requirements.

Lighting when working inside the boiler can be an artificial light source located outside. It is allowed to use portable electric lamps (voltage no higher than 12 V with a glass cap and metal mesh) or battery-powered explosion-proof lamps.

When working inside a tank boiler, a mechanic must use a safety helmet, rubber shoes, canvas or leather mittens, knee pads and armrests made of tarpaulin and cotton wool, and a rubber mat, a felt mat with a rubber layer or a dry wooden board underfoot.

Persons over 18 years of age who have passed a medical examination, trained in safe work methods and techniques, the use of personal protective equipment, rules and techniques for providing first aid to victims are allowed to work...

Analysis of the activities of an enterprise producing seamless steel pipes for the oil and gas industry

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Modeling and performing an elegant women's prom hairstyle on long hair. Creating a harmonious image using makeup and clothes

Do not pin special clothing with pins or needles, do not keep sharp, fragile or breakable objects in clothing pockets. Check by external inspection: o sufficient illumination of the working area, if necessary...

Modeling and performing an elegant women's prom hairstyle on long hair. Creating a harmonious image using makeup and clothes

hairdressing modeling hair make-up Perform only the work for which you have been trained, for which you have received instructions on labor protection and approved by the employee responsible for the safe performance of work...

Modeling and performing an elegant women's prom hairstyle on long hair. Creating a harmonious image using makeup and clothes

If a device (device) or equipment breaks down, threatening an accident at the workplace, in a hairdressing salon (steaming, leaking water and other malfunctions), it is necessary to stop operating and supplying water and electricity to it...

Modeling and performing an elegant women's prom hairstyle on long hair. Creating a harmonious image using makeup and clothes

Disconnect the infraheater, climazone, water heater, drying cabinet, hair dryers (dryers) and other devices from the power supply. Process the removable knives of the electric razor in accordance with the established instructions...

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Welding materials and equipment

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Creation of air conditioners

The method of industrial mountaineering is used in the production of steeplejack work for access (approach) to the place of work on building structures, buildings, structures, or to perform the work itself, when it is impossible...

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Before starting work, the person responsible for the safe performance of work must: - instruct workers in accordance with the work permit...

Creation of air conditioners

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Ice cream production line

Operating personnel must have a good knowledge of the operating principle and design of the machines being operated. Before starting work, it is necessary to check the condition of the main components. Do not operate the freezer if there is an ammonia smell...

Technological process for restoring the bipod shaft of the steering mechanism with the roller assembly

Before starting work, it is necessary to put your work clothes in order, tuck your hair under your headdress, prepare the necessary tools, safety devices (glasses, headphones, respirator), inspect the machine equipment...

The surface of the tank is cleaned, the walls are inspected and their thickness is measured.

A person working inside the tank is constantly monitored by two backups located outside it, who are obliged to:

• constantly stay at the tank hatch and watch the person working in it;
• hold a signal and rescue rope, the end of which is tied to a support;
• monitor the correct position of the gas mask hose, blower and intake pipe, as well as their serviceability;
• monitor the signals given by those working inside the tank;
• be located on the windward side of the lucalase.

The backup must be in the same equipment as the person working in the tank in order to provide immediate assistance or replace him.

If any malfunctions are detected (puncture of the hose, stoppage of the blower, breakage of the rescue rope), as well as when a person working in the tank tries to remove the gas mask helmet, work inside the tank must be immediately suspended, and the worker removed from the tank.

If a worker in the tank feels unwell, he must give a signal to the backup, stop working and leave the tank. If a worker loses consciousness while working inside a tank, backup personnel must immediately remove the victim. The maximum stay in the tank when working in a hose gas mask should not exceed 15 minutes.

While working inside the tank, it is necessary to ventilate it and systematically take air samples from the lower parts of the tank for analysis. If an explosive concentration of gas is detected in the tank, work must be stopped immediately and the worker removed from the tank.

After completion of the work, the person responsible for carrying out the work and the head of the gas filling station (warehouse) must personally verify that the container has been repaired and that there are no people, tools or materials in it.

“Occupational health and safety in the gas industry”,
A.N. Yanovich, A.Ts. Astvatsaturov, A.A. Busurin

Before an internal inspection, the tank must be emptied of liquefied gas in the following sequence: sediment is removed from the tank through the drain line; water and heavy residues, then the liquid phase is pumped, then the vapor phase is pumped out to an excess pressure of at least 0.5 kgf/cm2. The tank is disconnected from the pipelines of the liquid and vapor phases using shut-off valves and plugs with...

Immediately before lowering a worker into the tank, the person responsible for carrying out the work must check the health status of the workers through a survey, re-instruct all team members on safe work methods (each worker must sign the work order), check the quality of protective clothing, hose gas masks, life belts, lighting explosion-proof lamps, lanterns, etc. At the same time, an analysis is carried out in the tank: the content of hydrocarbons in ...

The team performing scheduled preventive maintenance of hydraulic fracturing equipment (GRU) must consist of three or more people. The size of the brigade is determined by the base management. All other scheduled maintenance and repair work must be recorded in the operational log. Work on routine preventive inspection and repair of hydraulic fracturing equipment must be carried out during the daytime. In case of insufficient natural light, it is allowed to use...

Tools and equipment, vessels for removing heavy residues from the container, all metal parts of belts and gas masks must be made of non-sparking materials or reliably protected from impacts, shoes should not have iron nails, squares or horseshoes. The use of aluminum and its alloys as a non-sparking material is not permitted. Before putting on overalls, shoes and equipment...

6.1. Containers to be opened, inspected, cleaned or repaired must be cut off from the existing process equipment and communications by shut-off valves, freed from the product, disconnected from the existing equipment and pipeline systems using standard plugs (according to the diagram attached to the permit) and Depending on the properties of the products contained in them, they are washed, steamed, and blown with clean air.

6.2. Work on installing (removing) plugs, included in the list of measures for preparing the facility and provided for in clause 6 of the permit work order, does not require additional execution of the permit work order and can be carried out both by operational personnel performing preparatory work and by personnel included in team to carry out this work.

Safety measures when installing (removing) plugs must be set out in clause 6 of the work permit for work inside the device

6.3. Before lowering people into them, heated containers must be cooled to a temperature not exceeding plus 30°C. In exceptional cases, if it is necessary to carry out work in conditions of higher temperatures, additional safety measures are developed (continuous blowing with fresh air, the use of thermal protective suits, shoes, frequent breaks in work, etc.).

6.4. Before starting work inside the tanks and for the entire duration of the work in the gas hazardous work area, a “Gas Hazardous Work” poster is posted in a visible place, which is removed after completion and only with the permission of the person responsible for the work.

6.5. To carry out work inside tanks, a team consisting of at least two employees(working and observing), and when working inside wells, collectors, tunnels, trenches and other similar devices and structures - by a team consisting of at least three employees.

As a rule, one person is allowed to stay inside the container. If it is necessary for a larger number of workers to stay in a tank, safety measures must be developed, included in the permit and additionally implemented, providing for an increase in the number of observers (at least one observer per person working in the apparatus), the procedure for entry and evacuation of workers, the procedure for placing hoses, gas mask intake pipes, signal and rescue ropes, availability of communication and signaling equipment at work sites, etc.

6.6. In all cases worker descending into the tank must wear a hose gas mask with a belt and a signal and rescue rope. The hose gas mask kit must be tested in accordance with the established procedure in accordance with OT-6.

If there is no visual connection between the worker and the observer, a system for giving conditioned signals must be installed.

6.7. When working inside a container watching must be at the hatch (manhole) of the tank in the same equipment as working, having an insulating gas mask in position "ready".

At the same time he must:

– monitor the signals and behavior of the worker;

– monitor the condition of the air hose of the gas mask and the location of the air intake device;

– descend into containers wearing a hose gas mask to provide assistance to the victim after prior notification to the person responsible for carrying out gas-hazardous work.

6.8. To protect the respiratory organs of those working inside the tanks, hose gas masks PSh-1, PSh-2 (by workers of technological installations, maintenance personnel), and air-containing breathing apparatus (by workers of the State Observatory) should be used.

Use of filter gas masks prohibited.

Work inside a container without respiratory protection (the worker has RPE with him, but does not use it, but keeps it in the “ready” position) can be authorized in writing by the chief engineer of the ZPKT, provided that the volumetric oxygen content in the container is at least 20% vol. (actual atmospheric), and the content of harmful vapors and gases in the container does not exceed the maximum permissible concentrations (MPC) of these substances in the air of the working area.

In this case, the possibility of harmful, explosive and fire-hazardous vapors and gases entering from the outside or being released from deposits, linings, etc. must be excluded.

Measures to ensure the safety of performing work inside devices without personal respiratory protection must be set out in the general plant instructions for organizing and carrying out gas hazardous work, in the instructions for workplaces, in the work permit and include:

– continuous guaranteed supply of fresh air to the device, ensuring normal air conditions in the device;

– continuous monitoring of the air condition;

– the presence of hose gas masks in the “ready” position for everyone working in the apparatus and observing;

– availability of signaling and communication equipment (light, sound, radiotelephone) near the work site;

– everyone working in the tank has a life belt with a signal and rescue rope attached to it and other measures to ensure the safety of workers.

NOTE :

Work inside wells, sewers, tunnels, trenches and other similar devices and structures without respiratory protection not allowed .

6.9. To lower a worker into a tank, to work inside the tank and to climb out of it, the stationary or portable ladders used must be tested in the prescribed manner and meet safety conditions.

Checking the serviceability, stability and reliability of securing the ladder at the place of work is carried out in the presence of the person responsible for the work.

6.10. When descending into the tank and leaving it, the worker should not hold any objects in his hands.

All spark-proof tools and materials necessary for work must be supplied (removed) into the container in a way that prevents them from falling and injuring workers, before lowering (after lifting) the worker into the container.

Lighting - no higher than 12V, corresponding to the category and group of the explosive mixture, is turned on and off outside the container.

6.11. If there are deviations from normal behavior in the actions of a person working inside the tank (signs of malaise, an attempt to remove the gas mask), as well as other circumstances that threaten his safety, the work should be stopped immediately and the worker should be evacuated from the tank.

6.12. After completing the work inside the tank, the person responsible for carrying it out, before closing the hatches, must personally make sure that there are no people left in the tank, that tools and materials have been removed, and that there are no foreign objects left and make a note about this in clause 16 of the work permit.

6.13. Carrying out work related to the depressurization of flare equipment and pipelines, as well as work in wells, sewer networks, tunnels and similar structures must be agreed upon (against signature in the work permit) with the heads of production facilities and service areas technologically related to these facilities, by which measures must be taken to prevent volley releases of harmful and explosive products to the work site.

6.14. During the period of work, open well hatches must be fenced and illuminated at night.

6.15. When applying protective coatings to the internal surfaces of containers, the implementation of which is accompanied by the release of harmful and explosive products, forced removal of these products should be provided.

6.16. Hot work in tanks is carried out with fully open hatches (manholes) and air exchange, ensuring normal air conditions in the work area.

When they are carried out, not only a work permit is issued for carrying out gas-hazardous work, but also a work permit for hot work in accordance with the requirements of the “Instructions for organizing the safe conduct of hot work at explosive, fire-hazardous and other facilities of ZPKT LLC Gazprom Pererabotka (OT – 03) a person authorized to carry out this type of work.

Developed by:

Commander of the gas rescue squad ZPKT V.A. Kotov

Agreed:

Deputy Chief Engineer for Health and Safety V.V. Basyuk

Chief mechanic of ZPKT Yu.S. Zhogin

Chief power engineer of ZPKT S.A. Leonov

Chief technologist of ZPKT O.E. Obukhov

Head of Production V.I. Kondratei

Head of PRO ZPKT R.A. Koishin

Chief metrologist of ZPKT A.A. Belyaev

Before being delivered to the depot, tanks must be cleaned, steamed and degassed at PPP.

Before starting work on the tank boiler, the air environment should be re-analyzed with a gas analyzer under the guidance of the deputy depot manager or foreman.

Before starting work on the tank boiler, the mechanic must check the availability of a certificate of form VU-19 on the suitability of the tank for repair, indicating the type of treatment, analysis results, signatures of the persons and the seal of the organization that carried out this work. In the absence of such an act, repair work on the tank is not allowed.

When working inside the tank boiler, it is necessary to open the cap cover and the drain valve, provide fresh ventilation with sufficient air exchange, and in cases where ventilation does not provide the required air frequency of the working area, respiratory protective equipment should be used (hose breathing device or hose gas mask) providing clean air supply to the breathing zone. In the cold season, the supplied air must be heated to 18-200C.

Workers should descend into the tank boiler for repairs using ladders located inside the boiler. In the absence of permanent ladders, portable wooden unframed ladders must be used, the length of which must be at least 3.3 m.

Work on top of the tank boiler must be carried out from mobile platforms or at a special workplace equipped with a cable for attaching a safety belt.

Work related to lowering the tank into the boiler must be performed by two mechanics.

Before lowering the tank into the boiler, the mechanic must put on a safety belt with a safety rope attached to it. The second end of the rope must be in the hands of the supervising mechanic, who must, when performing work inside the boiler, be constantly at the tank cap and be able to give and receive signals using the rope, and also, if necessary, provide assistance to the mechanic located inside the boiler.

Simultaneous work on the outside and inside of the tank boiler is prohibited.

To communicate between mechanics using a safety rope, the following alarm system is installed:

One jerk from below (from the boiler) - “tighten the hose and rope”, and they need to be tightened after repeating the signal of the observing worker located at the boiler hatch and receiving the same response signal from the boiler;

Two jerks in a row - “let go of the hose and rope.” This signal is given by the mechanic working in the boiler to allow movement inside the boiler;

Two jerks with breaks between them - “release the container” or “raise the container” (depending on where it is at the moment);

Repeated tugs given by the observing worker located at the boiler hatch, the mechanic in the boiler is obliged to go to the hatch or go upstairs. The same signal given by a mechanic working in a boiler means a requirement to immediately take measures to remove it from the boiler.

If there is no response to the rope pulls given by the observing worker located at the boiler hatch, he must raise the alarm and call the foreman, other workers and a medical worker to provide assistance to the victim.

Welding work inside tank boilers must be carried out in accordance with the requirements.

Lighting when working inside the boiler can be an artificial light source located outside. It is allowed to use portable electric lamps (voltage no higher than 12 V with a glass cap and metal mesh) or battery-powered explosion-proof lamps.

When working inside a tank boiler, a mechanic must use a safety helmet, rubber shoes, canvas or leather mittens, knee pads and armrests made of tarpaulin and cotton wool, and a rubber mat, a felt mat with a rubber layer or a dry wooden board underfoot.

Electric welding of a tank boiler is characterized by a high concentration of heat flux (more than 30 cal/g per 1 mm 2 arc spot area). There is a rapid transition of the welded metal and welding materials from solid to liquid state. The process is explosive in nature and takes place at very high temperatures (several thousand degrees in the arc zone).

When electric welding, the human body can be exposed to the following types of energy:

• - electric;
• - electromagnetic;
• - mechanical.

Each of these components poses a danger to humans.

Welding work at machine-building plants is carried out mainly in assembly and welding shops or departments. Harmful factors arising during the welding process can cause injuries (electric shock, burns from splashes of molten metal, etc.) and occupational diseases (electro-ophthalmia, pneumoconiosis, manganese intoxication...).

During manual electric arc welding, during work the welder deals with electrical installations - welding units and movable transformers, as well as various electrical equipment. This creates a risk of electric shock.

When welding with an alternating current arc, the operating voltage supplied from the welding transformer to the product should not exceed 70 V. All housings of welding installations, generators, and electric motors must be grounded. Welding units, machines and transformers are equipped with a casing to protect live parts of the primary circuit. The covers must be securely fastened. To reduce the risk of the primary voltage transferring to it during a breakdown, the secondary winding of the transformer should be reliably grounded together with the metal casing.

The open circuit voltage of a DC and especially an AC power supply is hazardous when the welder comes into contact with large metal surfaces, so when working in particularly hazardous conditions, such as when welding inside a metal container (tank boiler), avoid prolonged exposure no-load voltage, electric welding installations must have a lock, in which the welding circuit is automatically switched on when the electrode comes into contact with the work being welded and automatically switched off when idle. When working inside the boiler, complete electrical safety of the welder is ensured.

The blocking diagram is shown in Fig. 11.2. It can be seen that as soon as the welder touches the parts being welded with an electrode before starting work, the auxiliary transformer circuit, designed for a voltage of 12-24V, turns out to be closed. As a result of this, the contactor coil is excited and closes contacts K1 and K2, turns on the primary winding of the welding transformer and, at the same time, opens the short-circuit contacts. In this case, the capacitor coil will be connected in parallel with the inductor.

The welding current passing through the inductor causes a voltage drop across it, which powers the contactor coil. When work is completed or the electrode is changed, the arc breaks, the voltage at the inductor drops to zero and the contactor coil, losing power, opens the primary circuit of the welding transformer using contacts K2 and thereby disconnects it from the network. At the same time, contacts K1 are opened and the short circuit is closed. In addition to electrical safety, such a solution is of great economic importance, since the idling time is reduced, thereby reducing losses from idling, and the power factor of the machine is increased.

A) Closed grounding scheme

B) Zeroing circuit

Rice. 11.1

Rice. 11.2

Welding inside containers is characterized by the rapid formation of high concentrations of gases and aerosols in the breathing zone, as well as unfavorable meteorological conditions, and therefore requires special sanitary measures. Working conditions when welding inside tanks are aggravated by increased thermal radiation and uncomfortable body position of the welder. Research by the Institute of Hygiene and Occupational Diseases has established that the air temperature in small confined spaces increased by 6-10 0 C during 30 minutes of work, and the intensity of thermal radiation at the level of the welder’s face was 300 -450 kcal/m 2 *h. According to sanitary standards SN 245-71, when irradiation is more than 300 kcal/m 2 *h, in order to create normal working conditions, it is necessary to use air blowing of the workplace.

In accordance with “Sanitary Rules for Welding, Surfacing and Cutting of Metals” No. 1009-73, the mobility of air supplied to closed volumes should be 0.7-2 m/s in order to exclude the possibility of welders catching colds. The temperature of the supplied air during the cold season should not be lower than 20 0 C.

In accordance with the “Safety and Industrial Sanitation Rules for Electric Welding Work,” welding inside confined spaces without ventilation is not allowed.

Before welding tanks, the following must be carried out: cleaning, rinsing and ventilating them.

In workshops where welding is carried out inside tanks, it is necessary to install general exchange and local ventilation. In some cases it is necessary to use personal respiratory protection.

Ventilation of confined spaces can be carried out according to the following schematic diagrams:

• 1) creating an organized air exchange in the container: mechanical supply of clean outside air into the container; mechanical removal of air from it; combined action of inflow and exhaust;
• 2) removal of contaminated air directly near the electric welding arc;
• 3) ventilating only the welder’s breathing zone (by supplying clean air under the mask or under the shield).

A characteristic feature of tank ventilation is the need to use, in most cases, flexible hoses and high-pressure fans.

When ventilating a container with a supply stream from a stationary ventilation unit, clean (outside) air, heated in cold weather, is supplied to the container. With this method, the tank should be installed in fixed places. Flexible hoses of large diameters (~200-300mm) can also be used if there is a ready-made flange at the end of the tank. When determining the volume of supplied air, it is important that the air speed at the workplace is 0.7-2.0 m/s during manual welding, and when welding in shielding gases within the limits specified by the relevant standards.

The supplied stream of clean air must be directed from the welder to the arc so that harmful emissions do not enter the breathing zone.

The disadvantage of the scheme under consideration is that contaminated air is released into the workshop and must be removed by general exchange ventilation.

This can be avoided by simultaneously removing contaminated air from the container on the side opposite to the air flow using exhaust ventilation.

The device of one exhaust from the tank (with exhaust outside the workshop) has the disadvantage that air from the workshop, which is already partially polluted, enters the tank. The recommended volume of air removed per post is 2000 m 3 /h. With this method of ventilation, lower air velocities are created than when supplying a supply jet, but during the cold period the air does not heat up from the workshop temperature (16-18°) to that recommended for supply to containers (not lower than 20°).

When welding containers at non-stationary locations, when it is impossible to install the systems described above, mobile units are used.

Mobile units transfer partially contaminated air from the workshop into a container, and exhaust air with a high content of aerosol and gases is returned to the room.

To remove contaminated air directly from the welding arc, an air installation with small-sized portable local suction units has been developed. Dust and gas are removed directly from the welding arc using small-sized dust and gas receivers with flexible lightweight hoses of small diameter.

The following can be used as air movement stimulators:

• A) in long-distance systems - various vacuum pumps; for a small number of welding stations, water-ring vacuum pumps of the RMK or VVN type should be used; for a large number - multi-stage centrifugal machines of the brands TV - 50-1.5, TV - 70-1.6 and TV - 175-1.6, creating a vacuum of 2500 -3000 mm water column.
• B) in systems with a short work front (up to 6-8 m), high-pressure fans can be used, creating a vacuum of 1500 mm water column.

A sealed thin-walled steel pipe, laid along the possible front of electrical welding work, is connected to the stimulator. The length of the collector can be 100m or more. Fittings are welded to the manifold for connecting portable hoses. All fittings are equipped with plugs for hermetically sealed closure.

In high-vacuum installations, special rubber-fabric hoses of lightweight construction are used. At the air inlet into the hoses, small-sized portable dust and gas receivers with pneumatic suction cups - holders are installed.

The action of a pneumatic suction cup is based on the use of vacuum created by a traction stimulator. The vacuum in the suction cup necessary to hold the receiver and hose is ensured by locally increasing the magnitude of the vacuum using a diffuser pinch built into the hose, the narrowed cross-section of which is connected by a hollow sleeve to the cavity of the rubber hemisphere. The suction cup is attached automatically upon contact with the surface due to the rapid formation of a vacuum.

The suction cup is pulled off by squeezing the edges of the hemisphere with your fingers. Rearrangement of the suction cup is carried out, as a rule, every time the electrodes are changed. With proper operation of such local suction, the necessary sanitary and hygienic effect is ensured. The concentration of dust and gases in the welder’s breathing zone is reduced to a level close to the maximum permissible concentration. This effect is achieved by removing air from one welding station at 100-150 m 3 /h.

When manually welding structures at non-stationary locations, constantly moving exhaust ventilation receivers can be used, attached with hinges to the handles of the protective shields. Swivel joints allow you to change the angle of rotation of the receiver pipe, both in the vertical and horizontal planes.

When welding inside cylindrical planes, carried out on tilters, that is, performed only in the lower position, only a mobile dust and gas receiver can be used, which moves on rollers as the cylinder being welded rotates. To ensure the desired hygienic effect, 250 m 3 /h of air must be removed through such a receiver.

The required air exchange when harmful substances (gases, vapors and dust) are released into the room is determined by the formula:

Where K d is the maximum permissible concentration of harmful substances released into the room Kd = 6 for electrodes E46A brand UONI-13/55 according to GOST 12.1.005-88;

Kp is the concentration of harmful substances in the supply air, we take Kp = 0;

K in - the amount of harmful substances released into the room within an hour, mg/h.

Where Q p is the average ratio of the weight of dust released into the surrounding space to the weight of consumable electrodes, we accept:

Q p = 0.01 for automatic welding;

Q p = 0.04 for manual welding;

Fn - annual actual working time fund.

G e - annual consumption of wire and electrodes for electric welding, kg;

Where P is the annual program;

K e - the ratio of the mass of the electrode coating to the mass of the electrode wire, we take K e = 0.25 - 0.4 for automatic welding with flux;

K p - coefficient of transition to the seam;

G n - mass of metal consumed per product, kg.

Where g is the mass of deposited metal per meter;

t is the length of all seams on the boiler, m.

With automatic welding, the length of the seams is 130 m, and with manual welding - 85 m.

We determine the mass of metal per meter of seam.

Where is the specific gravity of the deposited metal, we take g/cm 3 ;

Volume of deposited metal.

Where KSh is the leg of the seam, we take KSh = 8 mm.

Substituting numerical values ​​into formula (11.13), we obtain

Substituting numerical values ​​into expression (11.12), we obtain

The mass of deposited metal per meter during automatic welding is g = 0.46 kg/m, then, substituting the numerical values ​​into the formula, we get

Substituting the numerical values ​​into formula (11.10), we obtain the annual wire consumption

The annual consumption of electrodes according to the formula will be

The annual working time fund can be calculated from the expression

Where P 0 is a coefficient that takes into account rest during working hours;

F k - annual fund of equipment operating time.

where t H is the working time per week, we take t H = 35 hours;

n cm - number of shifts, take n cm = 2.

Substituting numerical values ​​into expression (11.15), we obtain

Substituting numerical values ​​into formula (11.14), we obtain

Substituting numerical values ​​into expression (11.9), we obtain the average hourly dust emission in the workshop during automatic welding

and with manual welding it will be

The total average hourly dust emission in the workshop will be Kv = 245693.7 mg/h.

Thus, the required air exchange during the release of harmful gases can be calculated by substituting numerical values ​​into formula (11.8):

From the catalog we select the MTs-6 fan with a speed of 965 rpm and an air flow rate of L = 40,000 m 3 /h.

We select the number of fans from the expression

The power of the electric motor is determined by the formula

where L is the required air exchange during the release of harmful gases;

Design resistance under standard conditions, take kgf/m2;

Fan efficiency, we accept;

Feed efficiency, accepted.

Substituting numerical values ​​into formula (11.16), we obtain

Thus, from the calculation results it is clear that in order to ensure the necessary ventilation during the production of tank boilers through welding work, it is necessary to have at least one fan of the MTs-6 brand.

The cross-sections and lengths of the hoses and manifold are determined by calculation for each specific installation, depending on local conditions and the type of vacuum draft stimulator used in the system.

Where U is the air speed in the working section, we take 6 m/s;

F - working section area, constituting 25% of the total area Fob (F = 0.01 m 2). Fob - we take it equal to 0.04 m 2.

In this case, the effect of removing air from one welding station, the concentration of dust and gases in the welder’s breathing zone is reduced to a level close to the permissible concentration. With their help, the necessary working conditions will be maintained in the workshop. In the absence of local suction, personal respiratory protection should be used, especially when local exhaust devices cannot provide the required air parameters. When the concentrations of gases in the breathing zone are low, anti-dust respirators TTTB-1 “Lepestok”, “Astra-2” can be used.

When a welder works in conditions of high concentrations of not only aerosol, but also gases, hose gas masks PSh-1, PSh-2-57, DPA-5, ASM with forced air supply should be used. The disadvantage of hose gas masks used for personal respiratory protection is the lack of devices for heating the air, which limits their use in the cold season and filters for air purification,

The installation for forced air supply under the electric welder’s mask consists of the following main components:

• - masks;
• - hoses;
• - electric heater;
• - filter;
• - reduction washer.

Air for installation can be supplied from a high-pressure fan; from factory piston compressors or turbochargers. If high-pressure fans are used, the hoses should be short in length (up to 10m) with an internal diameter of 20-25mm.

The compressed air supplied by reciprocating compressors is usually contaminated with lubricating oil products, dust and water vapor. If the cooling of piston compressors is insufficient, the possibility of the presence of carbon monoxide in the compressor air cannot be excluded. To clean the air coming from piston compressors, a special filter should be installed.

When working, a welder experiences an increase in the volume of pulmonary ventilation as a result of the influence of factors such as forced body position, the influence of radiant heat, impaired thermoregulation and protective clothing. To ensure normal pulmonary ventilation, maintain hygienic standards of carbon dioxide and relative humidity, the grease should be supplied with at least 100 m 3 / h of air per minute. To maintain an excess pressure of about 0.35 kg/cm 3, another 20% of air must be added, that is, 120 l/min.

The required amount of air passes through a reducing washer with a hole in it of 1.7 mm in diameter. A mesh is installed in front of the washer to catch particles of dust or scale that accidentally get into the mesh behind the washer for compaction - a rowan gasket. The brass mesh with a mesh size of 0.3 mm in the light can be easily removed for cleaning.

The final purification of the air takes place in the filter and enters the electric motor with a voltage of 36 V and a power of 300 W, which is used to heat the air in the cold season.

An autogenous hose with an internal diameter of 12 mm is used to supply air to the welder. In the area from the manifold to the reducing washer, the hose is under network pressure.

When supplying air from a high-pressure fan, to which up to five masks can be connected, the air duct can be a lightweight vacuum cleaner hose with a diameter of 25 mm and a length of 2 m, assembled with couplings to the required length.

A 1m long medical rubber hose with an internal diameter of 8mm is installed from the belt to the visor. The air from under the visor, through a slot that expands slightly from the center of the mask to the sides, is evenly directed to its front wall.

On the front wall of the mask there is a folding frame mounted on an axis with a light filter with protective glass on the outside. When the frame is raised, the viewing window, with an area 4 times larger than the dimensions of the light filter, is covered with organic glass, the surface of which is treated with varnish made on the basis of silicon-organic compounds to prevent the formation of scratches.

Through the viewing glass, the electric welder can freely view the area being welded without removing the entire mask, and thanks to the presence of organic glass and a slight excess pressure, he can breathe clean air.

Clean air, washing the front wall of the mask on which the plexiglass is fixed, eliminates fogging without cooling the skin of the face.

Along the inner perimeter of the mask there is reinforced fabric (black sarta), which is tightened with an elastic band along the welder’s chin and cheeks. Through this soft material, excess air, including that exhaled by the welder, freely escapes. The fabric is treated with a special fire-resistant impregnation to prevent ignition from a spark.

A replaceable gauze cover is fastened with pins to the edge of the fabric in contact with the face. In the event of a transition to a new workplace, a supply of fabric is provided, allowing you to completely retract the mask by turning it on the headband.

This design is characterized by low dust concentration, good subjective feeling of the welder and well-being. The absence of sweat from the skin of the face made it possible to use a mask with air supply during welding work inside the tank boiler.

To protect the eyes and faces of welders and support workers, special shields and masks are used. To protect the eyes from the blinding visible part of the radiation spectrum, ultraviolet and infrared rays, protective light filters appropriate for specific conditions must be used in glasses, shields and masks.

To protect the eyes of electric welders, ShchEU shields of a universal type for electric welders are used. Due to frequent occupational eye diseases of auxiliary workers, MVE protective masks are used for them. The mask consists of a fiber screen, a headband and an apron. At eye level there is a rectangular frame with a set of glasses: an outer colorless cover glass and an inner two-color protective light filter, which allows you to see when the welding arc is burning and not. The split leather apron protects the lower part of the face and neck from metal splashes and radiation. To protect the eyes of crane operators in assembly and welding shops, it is recommended to use Voskhod safety glasses.

To protect the head, electric welders should be provided with protective helmets made of non-conductive materials.

Electric welders must be provided with protective suits, gloves, and special footwear. Overalls must be durable, fire-resistant, lightweight, breathable, non-electrically conductive, and have low shrinkage. When the risk of electric shock increases, welders should be provided with dielectric gloves, galoshes and mats. When plasma processing, ceiling welding, or working in cold conditions, welders are given oversleeves, knee pads, and armrests made of fire-resistant or heat-protective materials. To protect welders and auxiliary workers from injuries and burns, special boots with toes protected by metal plates and a side fastener are used to prevent sparks and drops of molten metal from entering.