It is difficult to imagine modern pipelines without valves. Gate valves, gates, valves, valves - all these products allow you to regulate the pressure in pipeline systems up to the complete shutdown of the transported medium. Stop valves are installed on any type of pipeline - oil, gas, food production, water, steam, etc. The range of valves is varied, and is selected for any transport environment and conditions. The largest group of shut-off and control valves in terms of distribution are gate valves. The gate valves are widely used due to their design versatility and high performance indicators (temperature of the ambient and transported medium, pressure, alkaline / acidic media, etc.). According to the degree of tightness, the valves are divided into classes A, B, C, D, B1, C1, D1. The tightness classes are regulated by GOST 9544-2005.

• Wedge gate valves
• Parallel gate valves
• Pinch valves
• Gate (or knife) gate valves

If we abstract from the nuances, the structure of the valve in general terms is a steel or cast iron body and a cover, which are interconnected. From the body there are connecting pipes, through which shut-off valves crashes into the pipeline. According to the variability of the types of connections, the main types of valves can be distinguished:

• Welded - nozzles are pipes corresponding to the diameter of the pipe, which are cut into the pipeline using electric arc welding. Not so common.
• Flanged. At the ends of the branch pipes there are flanges through which the installation on the pipeline takes place. This type of connection is more common because allows for quick hermetic installation of the valve, as well as provides further easy dismantling of the valve, if necessary.
• Coupling valves are the most rare view connection, can be found up to a diameter of 50 mm.

The main locking part in the gate valve is a wedge (which can be rubberized, or it can be steel). When the stem (spindle) is rotated, the wedge moves in the valve body perpendicular to the flow of the pipeline medium. When closed, the wedge seals against the sealing seats, which are located on both sides of the wedge, most often at an angle. When the flywheel (or handwheel) rotates, the spindle rotates around its axis, which sets the wedge itself in motion. This is a very simplified wedge gate valve diagram that may vary in detail from manufacturer to manufacturer.

The valve body can be made of brass, bronze, steel and cast iron. Brass and bronze gate valves are produced in a sleeve design and are rarely used. Steel gate valves are more commonly used when high temperatures ah internal environment. Cast iron valves are installed on most housing and communal services facilities due to their low cost and ease of installation, but they require careful handling during installation, since cast iron is very fragile and can crack upon impact, twisting and compression.

V recent times gate valves equipped with an electric actuator have become very popular. The electric drive allows you to quickly open or close the locking mechanism, and this can be done remotely. One operator is enough to control the operation of the valves on the pipeline section.

Structural types of valves

Since the gate valve devices are insignificant, but still differ, it makes sense to dwell on each type in more detail.

Wedge gate valves - these valves use a rigid, rubberized or double-sided wedge that fits tightly at an angle to the seats and seals the flow. Depending on the operational parameters, one or another wedge option is selected:

• Rigid wedge - allows you to achieve reliable tightness of the assembly, but requires high accuracy of fitting the wedge and sealing seats (ideally, an identical angle is turned on the wedge and seats, this is the only way a high tightness of the device is achieved). The main disadvantages can be considered frequent jamming due to temperature changes in the internal environment, as well as wear of rubber gaskets and O-rings. If the valve mechanism is jammed, then it is very difficult to open it!
• Double-disc wedge - this version of the locking mechanism implies two discs connected to each other. Thanks to this design, the wedge self-aligns when adjacent to the sealing seats, which allows some imperfections when turning the corner of the seats and wedge. Despite the fact that the double-disc wedge complicates the valve mechanism and increases the cost of the product as a whole, the advantages of this option are obvious - long term service of rubber seals, reliable tightness, less effort required to open / close the mechanism.
• The resilient wedge is a type of double disc closure. The two discs are joined together by an elastic material that can deform and fit into the seats when the valve is closed. Thus, the elastic wedge is the golden mean between the rigid wedge and the double disc. For example, an elastic wedge allows you to neglect the exact fit to the seats, and its structure is more reliable than that of a two-disc mechanism.

Parallel gates differ from all others in that the sealing rings are not located at an angle, but strictly parallel, and the locking mechanism itself consists of two discs, which, with the help of a special wedge, fit tightly to the sealing seats.

Gate valves (which are more often called knife gate valves) are an even simpler design in which the gate is located strictly perpendicular to the medium current. It is most often installed on sewers, slurry pipelines and other systems where the medium is thick and high tightness of the unit is not required. In this case, the shut-off element, as it were, cuts the transported stream, for which the valves are called knife valves.

Pinch valves are the most unusual type of valves, fundamentally different from the rest and the most rare. This type of valve has neither sealing seats nor a closing element per se. It is a rubber hose that most often transports a viscous medium and passes through the valve body. With the help of the rod, the hose is pinched and completely blocks the movement in the overpass. Typically, such valves are used on small-diameter pipelines, where slurry, sludge, various impurities, etc. act as a medium.

Spindle location

By the type of extension of the spindle, the gate valves can be divided into two large groups:

• Gate valves with a rising spindle are a design where the spindle is placed outside the valve body without contact with the transported medium. Thus, the threaded connection is accessible for maintenance and inspection and does not corrode in the valve body. But such a design has a number of disadvantages - due to the fact that when the flow is opened, the spindle extends from the valve to a length equal to at least the diameter of the pipeline, space is required for easy access to such a mechanism. Due to the design features, the mass and headroom increase, which is also important to consider when designing a pipeline. But such products can be installed on especially important objects, since the service life of the oil seals and other working elements of the mechanism is increased, and it is possible to monitor the condition of the spindle thread and carry out timely repairs and maintenance.
• Gate valves with a non-rising stem - in such devices, the nut-spindle running assembly is completely in the valve body, does not move beyond the valve and is in contact with the transported medium. As a result, the spindle and the sealing elements are corroded by the medium. It is recommended to install such valves on pipelines transporting water, oil and other non-aggressive liquids without impurities, since during operation it is impossible to monitor the condition of the spindle and make scheduled repairs without disassembling the valve. Because of this, such fittings are not recommended to be installed on especially important pipelines, but they are indispensable in narrow wells and other hard-to-reach places due to its relatively small size.

Advantages and disadvantages of gate valves

Gate valves are the most popular type of valves used in our country. This is due to the following advantages:

• Relatively simple design of the locking mechanism;
• Relatively small installation length, which is convenient for wells, oil wells, etc .;
• Variability of use - valves can be used on various types of pipelines with a variety of operating parameters;
• Possibility of changing the direction of flow of the transported medium in the opposite direction.
• Low hydraulic resistance;

The last favorable factor influenced the widespread use of valves on main pipelines, where the absence of hydraulic resistance is suitable for high speeds and pressures of the transported medium.

The main disadvantages of valves include:

• Long opening / closing time of the mechanism;
• Increased headroom (especially important for gate valves with a rising stem, since the stem extends at least by the nominal bore diameter)
• Rapid wear of rubber O-rings, laborious repair and maintenance of parts inside the valve body;
• Expensive repairs at a low price for valves - often valve repair is at least 50% of its original cost.

It is used in various industrial fields, and it can be divided into two types: for general technical purposes and intended for use in special conditions.

All types of valves are made from ductile iron or steel.

Shut-off valves of general technical importance are required in various industrial sectors and construction. Its operation is carried out on water pipelines, gas pipelines, steam pipelines. All types of valves are made from ductile iron or steel. They come in contact with water, steam, gas, oils. Shut-off valves include full-opening fittings: plug valves, valves, fittings with a through channel, which has the structure of a Venturi tube.

Characteristics of the main types of valves

Industrial production of all types of valves includes the manufacture of taps, valves (gates), gate valves and dampers. For shut-off valves, the size is up to Dy = 300 mm, where Dy is the diameter of the passage. The shut-off valves are operated in dead-end areas. They can be used for spindle bellows seals. Ball valves and valves of simple design are widespread. The gate valves have a simple device: short length, low hydraulic resistance. They are of two types: parallel double disc and wedge. With low pressure, it is necessary to use double disc valves, high pressure requires the use of wedge valves. Their wedge can be solid, elastic or composite.

What are cranes for? Their types and purpose

Cranes are installed on pipelines, water pipelines, steam pipelines, gas pipelines. The operated cranes are characterized by small dimensions and low resistance. The weight of the crane ranges from 0.881 kg to 8.64 kg. Diameter d in inches from 1 to 3 d. Two types of valves are widely used: cork and ball valves. Depending on the method of sealing, they are subdivided into tension and stuffing boxes.

The taps are connected to the pipeline using a coupling, flange or welded to it. Cork, gas, coupling, cast iron valves are used on pipelines supplying natural gas. Operating temperature is tp< 50°С. Установка осуществляется в любом положении. Изготавливаются из чугуна. Соединение крана с трубопроводом происходит за счет резьбовой муфты. Параметры для работы кранов: рабочее давление - Pp=0,1 МПа, tp< 50°С.

Another type of valves is cast iron stuffing box couplings. Installed on pipelines supplying water or oil. Working temperature is tp< 100°С. Положение крана при установке - любое. Изготовлены из чугуна основные детали крана: корпус, пробка, сальник. Сальник набивается пенькой или резиной. Давление среды составляет Pp= 1,0 МПа, если tp< 100°С, где Pp - давление, а tp °С - рабочая температура среды.

Small-sized valves, or ball valves, are characterized by low resistance, but at the same time they have high quality, therefore, their operation is permissible where the pipeline has a large diameter. The crane is made of cast iron. Fluoroplastic-4 is used for sealing rings. The oil seals are stuffed with hemp. The pressure in the working medium should be Pp = 1.0 MPa, and tp< 100°С.

Flanged steel valves are connected to the pipeline with flanges. Large cranes have a worm gearbox. The crane is controlled by a flywheel. Steel crane. On pipelines transporting gas at temperatures from -40 to + 70 ° C, lubricated steel flanged valves or with welded nozzles are used. These cranes are only installed in an upright position. Their work is carried out at low and high temperatures from -40 to + 40 ° C. The cranes are controlled remotely, and at the same time, manual control can be performed using a handwheel.

Device, use of shut-off valves

Most often, some types of shut-off valves are used, which are installed on pipelines and regulated by a flywheel or an electric drive. There is also a remote control.

For cast-iron shut-off coupling, the body is sealed with a PTFE-4 ring or a rubber or leather ring. They are installed on pipelines through which steam, water and air are transported. The connection is made with threaded couplings. The stuffing box is packed with AP impregnated with asbestos.

In pipelines transporting water at temperatures up to 50 ° C, shut-off coupling valves made of cast iron are installed. They work in any position. Water is supplied under the spool. The valve body is made of cast iron - leather; all gaskets are made of paronite. The oil seals are stuffed with asbestos.

In pipelines through which water or air is transported, the ambient temperature is + 45 ° C, shut-off valves with an electromagnetic drive are used. They work at high temperatures, up to + 50 ° С. When installed, the solenoid actuator itself points upwards. The cover and spool are made of steel, and the body is made of cast iron. The valve is powered by an electromagnetic drive. Can be operated manually.

Purpose and device of dampers

The dampers are used on pipelines with a diameter of 2200 mm. They have a simple structure; they are easy to operate, relatively cheap and lightweight. The dampers are easy to operate manually. Some dampers are hydraulically or pneumatically reinforced. Controlled electric drives include dampers with a diameter of 300-1600 mm at PN = 1.0 MPa.

On pipelines through which water is transported, flangeless dampers are installed for PN = 1.0 MPa. The shut-off element is sealed by a rubber ring, which is installed in the groove of the disc. Rotary shaft connected to the body, and the cuff - with rubber rings, seals their movable connection. The entire damper body is made of cast iron; made of steel - rotary shaft.

The dampers, controlled by an electric drive, are placed on the pipeline with an electric drive up, and the drive shaft is located vertically. Manual dampers can be installed in any position.

The dampers are flanged to the pipeline. Welding can also be used for this purpose. They are controlled by an electric drive. For dampers with a diameter of 300 to 600 mm, a manual gearbox is provided. The rubber ring on the disc serves as a seal. The rotary shaft is movably connected to the housing, sealed by a bushing with locking rings. The damper is made of 40X steel. Works at working pressure up to Pp = 1.0 MPa.

Electric actuators for flangeless steel dampers for PN = 1.0 MPa have a diameter PN of 1200 to 200 mm, power from 3 to 5.2 kW. The time during which the damper opens or closes is 1.5 to 1.8 minutes.

Gate valves - shut-off devices on technological lines

Dampers are devices of short length; they are used on highways and technological lines. provides for the presence of a non-rising or rising spindle. To close or open the passage, the spindle makes many turns: such valves are electrically driven. Wedge gate valves have a non-rising stem, flanged, cast iron, pressure PN = 0.25 MPa. They have a remote control. Diameter - from 800 to 2000 mm, weight - from 1772 to 14015 kg. The electric actuator has a diameter Dy from 800 to 2000 mm, opening or closing time from 2.3 to 5.8 minutes. Installation is carried out vertically, the electric drive is directed upwards. You can put the valve so that the spindle is in a horizontal position. For this, the worm gear and the roller bearing are coated with a very thick grease. The electric drive must be supported.

The connection to the pipeline takes place by means of flanges. The main parts are made of cast iron. The gasket consists of paronite; stuffing box packing - impregnated asbestos. Wedge construction - rigid or resilient.

For pipelines through which fuel gas flows and the supply temperature for which reaches 100 ° C, double-disc wedge valves are used; their spindle is non-rising, they are made of cast iron, PN = 0.6 MPa. Manually operated. Installation can be done in any position. Paronite serves as a gasket. The shut-off element is sealed with cast iron rings located on the discs and the body.

Double-disc wedge valves are installed on pipelines transporting coke oven gas. They have a sliding spindle and are made of cast iron. They are placed in a working environment with a pressure of Pp = 1.8 MPa for a gate valve with a diameter of 1300 mm and a temperature of 200 ° C. Gate valves with large diameter, 1500 mm, operate at a temperature of 85 ° C and Pp = 0.05 MPa. It is controlled by an electric drive, whose power is 3 kW. The valve has cast iron parts: body, cover, discs, post, - and a steel spindle. The stuffing box is made of asbestos.

Welded steel gate valves are installed on the pipeline through which oil and oil are pumped. They have a retractable spindle. Equipped with branch pipes. Installed in an environment with temperatures up to 250 ° C. They put the valves in any position. The entire valve is made of carbon steel. Steel 20x13 is used for the spindle.

Special shut-off valves for aggressive media

Shut-off valves operated in special environments are divided into the following types: taps, valves, gate valves. The choice of installation of one type or another depends on many indicators of the environment itself. Tightness, service life, and valve reliability are taken into account. Locking devices are widespread: diaphragm valves, ball valves, hose valves.

The valves are the most frequently used. For valves, the spool and seat are reliably mated; due to this, there is no friction. The stuffing box assemblies were replaced with bellows. Valves create a lot of hydraulic friction, and this is their disadvantage.

In a liquid medium, brass shut-off valves are installed, working pressure Pp = 1.6 MPa. Installation is carried out in any position. The valve is connected to the pipeline using a threaded coupling. The whole body is brass. The stuffing box is stuffed with asbestos.

In vaporous media at Рр = 1 MPa and temperatures up to 50 ° С, the valves have a brass O-ring. The same ring on the spool is made of rubber, you can also use a leather ring. The stuffing box is stuffed with asbestos.

Shut-off valves, gummed to PN = 0.6 MPa, have a protective coating, which consists of rubber. Diaphragm valves operate in an environment with a pressure of 0.6 to 1.6 MPa. As a material for the membrane and protective coating polyethylene, rubber or fluoroplastic is used.

Bellows shut-off valves made of corrosion-resistant steel are installed for operation at temperatures up to 350 ° C. Operate under vacuum up to 0.5 Pa. Pipeline connection - flanges. It is also possible to connect with pipes or pins. There is a paronite gasket between the body and the lid. There is also a connection without gaskets. The valve is operated manually. Porcelain shut-off valves have the entire body made of porcelain. Glaze belongs to anti-corrosion coatings.

Gate valves in aggressive environments are not widely used. Rising stem valves are not used. The bellows must not be used. On rising stem valves, it makes a large stroke in the stuffing box, which wears out quickly. They also require a lot of corrosion-resistant steel for coating, which is very expensive in itself.

The choice of modern shut-off valves meets all the requirements for production conditions.

Under shut-off valves understand various devices designed to control the flow of liquid transported through the pipeline.

Depending on the purpose, it is subdivided into:

1. Shut-off - which is designed to completely shut off the flow of fluid from pipelines (gate valves, valves, taps, valves).

2. Shut-off - non-return fittings - which serve for the passage of liquid in one direction and locking in the opposite direction (check valves).

3. Safety - which provides a partial release or bypass working fluid when the pressure rises to the value of the threatening strength of the system, and also prevents the reverse flow of liquid (safety valves).

4. Control valves - for flow regulation and level maintenance (valve regulation and level regulators).

Gate valve- a shut-off device in which the passage is closed by translational movement of the shutter in the direction perpendicular to the flow of the transported medium.

Compared to other types of shut-off valves, gate valves have the following advantages: low hydraulic resistance with a fully open passage; no flow turns working environment; the possibility of using to block flows of a medium of high viscosity; ease of maintenance; relatively small face-to-face length, the ability to supply the medium in any direction.

The disadvantages common to all gate valve designs include: impossibility of using for media with crystallizing inclusions: small allowable pressure drop across the gate (in comparison with valves); low gate response speed; the possibility of receiving a water hammer at the end of the stroke; high difficulty in repairing worn valve sealing surfaces during operation.

Valves are classified according to their strength into:

1.steel - for high pressure

2. cast iron - for pressure up to 16 kgf / cm 2.

Gate valves are available with a rising stem and with a non-rising stem, when the flywheel itself rises when opening. There are parallel dies, maple, the flow area overlaps in the vertical plane.

When looking at the structural type of valves, one should proceed from the following:

1. type of working environment;

2. chemical composition working environment;

3. pressure of the working medium;

4. working temperature;

5. the presence of reasonable requirements for the tightness of the shutter;

6. the diameter of the pipeline.

Wedge gate valves with a solid wedge are intended mainly for hermetic shut-off of pipelines with a high working pressure of a non-aggressive medium, both liquid and gaseous.

Wedge gate valves with resilient wedge are mainly used for tight shut-off of pipelines with oil and gas media of high temperature and high working pressure of the medium. It is not recommended to use gate valves of this type for work in crystallizing media or in media with mechanical impurities.

Gate valves with a compound wedge are recommended mainly for pipelines with an average working pressure of the medium, both liquid and gaseous, without solid and abrasive inclusions. The temperature of the working medium is set depending on the materials of the sealing surfaces of the valve.

Parallel valves are intended for installation on pipelines in processes where a sufficiently tight shut-off of the pipeline is not required at high operating pressures. The medium may contain a small amount of mechanical impurities.

Single-disc valves are used, as a rule, for pipelines with high t and average pressure of the working medium, in which it is required to ensure the passage of the medium in case of incomplete shut-off of the pipeline. With increased requirements for the tightness of the passage block, the most acceptable medium is non-crystallizing liquids with a sufficiently high viscosity, for example, oil, fuel oil, etc.

Double-disc valves are recommended for tight shut-off of pipelines with medium pressure of the working medium (both liquid and gaseous) containing a small amount of mechanical impurities. The medium temperature depends on the material of the sealing surfaces of the valve.

Gate valves with an elastic seal of the gate are designed for tight shut-off of a pipeline with a low temperature and medium pressure of the working medium, both liquid and gaseous.

Gate valves with a rubberized coating of the inner cavity are used for hermetically sealing pipelines with working media that are highly aggressive at low operating temperatures, as well as containing abrasive inclusions.

Gate valves with a bypass (bypass) are used mainly for pipelines with high pressure of the working medium.

Valve- the locking device is pushed onto the spindle, the flow area overlaps in the horizontal plane.

By the design of the body, the valves are divided into: straight-through, angle, direct-flow and mixing.

The classification of valves according to their purpose is essential: shut-off, shut-off and control valves and special ones. In turn, regulating valves can be subdivided according to the design of throttling devices into valves with profiled spools and needle valves. Similarly, shut-off valves are subdivided into poppet and diaphragm valves according to the design of the closures, and according to the method of spindle sealing, into stuffing box and bellows valves.

Straight-line valves are designed for installation in straight pipelines.

Disadvantages: relatively high hydraulic resistance; the presence of a stagnation zone; large building dimensions; the complexity of the structure of the case and the relatively large weight.

Angle valves are designed for connection of two parts of the pipeline, located perpendicular to each other or for installation in a turn. They work at pressures of the working medium less than 64 kg / cm2 and at low temperatures.

Direct-flow valves. Advantages: relatively low hydraulic resistance; compact design; lack of stagnation zones. Disadvantages: long length and relatively heavy weight.

Mixing valves are used to mix two streams of a liquid medium in order to stabilize its temperature, concentration of reagents, dilute the main medium, maintain quality, etc. A simpler solution to the mixing scheme is obtained when using mixing valves, in which two streams are mixed directly in the body of one valve. Their use gives a high economic effect due to the fact that instead of 2 valves and a special mixer, only one valve is used.

Diaphragm valves (diaphragm) are designed to shut off media flows at low temperatures (up to 100-1500C) and the absence of a stuffing box; stagnation zones and pockets; low hydraulic resistance; small overall dimensions and weight. The main disadvantage is the relatively short membrane service life.

Bellows valves are designed to operate in environments, the leakage of which into the surrounding atmosphere is unacceptable due to high cost, aggressiveness, toxicity, explosion or fire hazard, toxicity, etc. Advantages - complete elimination of fluid leakage and reliability of the sealing element.

Shut-off and control valves allow manual or remote control medium flow rate by changing the hydraulic resistance of the throttle pair with reliable fixation of intermediate positions even in case of accidents in the drive supply line or with difficult access to the valve, and also reliably shut off the pipeline.

Needle valves can be either mash or regulating. They have found wide application in the regulation and throttling of small gas flows, with large values ​​of pressure drops across the throttling device.

Tap- the flow area is opened or closed with a plug, it is used for diameters up to 50 mm, for pressures up to 40 kgf / cm 2

Tapered valves can be classified into the following types: tension valves, stuffing box valves with lubrication, and valves with clamping (or lifting) plugs.

Tension cocks are used for mass production and normal conditions operation (for example, kitchen gas taps). They are mainly used for free-flowing or viscous media where high liquid or gas tightness is not required. Mainly, tension valves are used for low working pressures (up to 10 kg / cm 2) or for media, the passage of which into the environment is not dangerous.

Stuffing box valves are widely used for liquid and gaseous media at pressures of 6-40 kg / cm 2.

Lift-off valves are not recommended for media containing solids and for suspensions, as the ingress of solid particles between the body and the plug can cause a loss of tightness with damage to the sealing surfaces, as well as for polymerizing or very viscous media.

Cylinder valves can be divided into 2 groups: metal sealed valves and resilient sealed valves.

Valves with a metal seal are mainly used for highly viscous media (fuel oil, coal tar pitch, etc.)

Valves with a resilient seal are used mostly with a metal plug and a non-metallic resilient seal in the seat.

Ball valves are used with lubrication and for high medium pressures and large passages (mainly for main gas pipelines and oil pipelines). They are divided into 2 types: floating plug cranes and floating ring cranes.

Floating plug valves are of 2 main types: with lubricated metal rings, with non-metallic rings made of pure plastics, rubbers.

Bellows valves are very expensive to manufacture due to increased requirements for manufacturing accuracy. The presence of a lifting plug - does not allow its use in viscous and polymerizing media.

Valve products belong to a special type of products for pipelines, the purpose of which is to promptly regulate the flow rate of the working medium to ensure the specified parameters of the technological process. The action of the shut-off valves is aimed at closing, opening, changing the direction and speed of the working gas / liquid. In addition, the shut-off valves should include drainage and control items that serve to discharge the carrier from pipeline systems, technological devices, and supply the carrier to the control and measuring devices.

Armature of this type is present in all pipelines of industrial production, technical household facilities (heating, gas, water supply, sewerage, etc.), and makes up at least 80% of the total used products in the line. Gate valves, gates, taps, valves and gates are most widely used as shut-off elements.

The choice of materials from which these parts are made is currently quite wide:

• metals (titanium, aluminum);
• alloys (cast iron, steel, bronze);
• polymer and synthetic materials eg polyvinylidene fluoride (PVDF), chlorinated polyvinyl chloride (CPVC), polyethylene (PE), polypropylene (PP).

When choosing a locking device, the following are guided technical characteristics: connecting diameter, purpose and material from which the body and the working part of the pipeline are made, closing speed. Special requirements: long service life, high strength, reliability, safety, corrosion resistance of the material to the working environment, tightness, ease of installation and ease of use.

It should be noted that the working environment of the pipeline quickly damages the products of shut-off valves, abrasion of the sealing elements, wear, corrosion processes occur, therefore it is necessary to timely carry out technical control of the equipment, flushing of the main systems, repair or replacement of the product.

Depending on the purpose of the technical object, shut-off valves are divided into categories:

• industrial (general industrial, special) - used in production different kinds activities, including the national economy;
• ship - operated in the specified specific conditions of sea and river transport;
• plumbing - pipe fittings for household use, used in gas stoves, water heaters, bathrooms, boilers, etc.;
• custom-made - designed, manufactured and operated in accordance with specific specified technical requirements, for example, in unique, experimental industrial facilities.

The functions performed by this type of valves are extensive: control, distribution and mixing, safety, protective, shut-off, phase separation.

In this article, we will consider the types of valves, the action of which is aimed at changing the cross-sectional area of ​​the pipeline to regulate the flow rate of the carrier or to stop it completely.

Types of valves

Gate valve

The main difference between this part is that the locking (regulating) element is a sheet, disk or wedge, which can move back and forth in a direction perpendicular to the direction of movement of the working medium. This type of fittings belongs to the industrial category and is used mainly in pipeline communications of housing and communal services and industrial production. Gate valves are divided into full-bore and truncated, their device allows you to smoothly adjust the flow rate and prevent hydraulic overloads.

The considered type of products has a number of advantages: simplicity of design, a wide range of operating conditions, small face-to-face length, low hydraulic resistance, which is especially important when used in pipelines with a high speed of the working medium. Disadvantages of valves are determined by their design: enough big time, spent on closing or opening the shutter element, wear of sealing parts, difficulty in maintenance.

The domestic industry produces gate valves with a non-rising stem and a rising stem. Gate valves are installed regardless of the direction of flow in the pipeline, since their design is symmetrical. Withstand working pressures from 2 to 200 atmospheres, connecting diameter varies from 8 mm to 2 m.

Valve

The valve, as a type of shut-off valve, performs a regulating function and allows you to change the flow rate of the carrier in the pipeline up to the termination of its supply. With their help, a given level of pressure in the line is maintained and the flows are mixed in the required proportion.

In the valve, the working element is located on the spindle, which reciprocates from the rotational movements of the flywheel. The movement of the spindle can be carried out automatically using servo drives and manually.

These products belong to the industrial category and are most often found in household objects of housing and communal services. The most common type of valve is straight-through, placed on straight sections of highways. One of the disadvantages of this type of fittings, in addition to direct-flow valves, is a large hydraulic resistance, which limits their use in special technical objects. The advantages of valves are low cost, availability, reliability, ease of repair and maintenance during operation.

Shut-off ball valve

The difference in the design of the shut-off valve lies in the simplicity of execution: the shut-off element is made in the form of a ball, a cylinder and, which is quite rare, can be of a conical shape. Cranes are available with full bore and not full bore. In full bore valves, the bore diameter always corresponds to the diameter of the connecting bore to the pipeline, in non-full bore valves, respectively, the bore diameter is smaller.

The work is carried out in the extreme modes "closing" and "opening". Its main function is aimed at blocking the movement of the work flow. The advantages, disadvantages and operating conditions are determined by the material from which the crane is made. For example, plastic valves PP, PE are resistant to aggressive media, but are subject to the destructive action of mechanical impurities in the working environment. Stainless steel faucets can withstand high operating pressures and temperatures, but from a domestic use point of view, they have a significant cost.

Valve

Valves (non-return) refer to protective pipeline fittings, functionally designed to prevent the reverse flow of the working medium in the technological scheme. By passing the working medium in one direction, the valves do not allow liquid or gas to return.

With their help, various production equipment (pumps, tanks, apparatus, etc.) are protected, and the damaged section of the pipeline is excluded in case of leaks of the working medium from the general technological process, which is extremely important in the event of an emergency.

There are valves with a spherical or cone-shaped closure element design, the movement of which occurs in a direction parallel to the movement of the carrier. The flow passing through the working window of the valve presses the shut-off element against the base of the device, which stops its movement in the opposite direction. Reverse valves are manufactured both built into the components and assemblies, and as an independent form. As a rule, check valves are mounted on horizontal straight sections of pipelines in the direction of the operating flow.

Valves having comparatively simple design, nevertheless, provide reliable and tight shut-off of the working flow, due to which they are widely used for gaseous and liquid working media. They are used in a wide range of pressures (from 5 · 10 -6 to 2000 atm.) And operating temperatures (from minus 200 to plus 600 ° С). Suitable for pipe structures of relatively small diameters.

Gates

A shutter is a shut-off valve device used to ensure tightness when the working flow is shut off. It can work in the "regulation" and "overlap" modes. It is the most convenient and simple type of shut-off valves for maintenance and operation, has a low cost and market availability.

The shutter device is designed in such a way that the locking element rotates around the axis on which it is located. The most common version of this butterfly valve device is the Butterfly.

The gate position can be controlled manually using a handle and mechanically using a gearbox or an electric drive. The advantages of butterfly valves "Butterfly", such as ease of maintenance, installation and replacement of sealing parts, low headroom and weight, as well as long service life and affordable cost are widely used in pipelines for domestic use.

The domestic industry produces a wide range of valves that meet general and special requirements, high quality and modern technologies. The cost of such products can vary widely from 100 rubles. up to several tens of thousands of rubles, which is determined by the material, purpose, size, manufacturer.

Shut-off valves

Under the heading "Accessories" we will consider shutoff valves. Without valves, it is impossible to imagine any kind of pipeline system. Shut-off valves – These are pipeline fittings that have found wide application and usually account for up to 80% of the total number of products used. The name "shut-off valves" means to all of us well-known valves, ball valves, gate valves and so on. With their help, you can open or vice versa, close the movement of liquid or gases in the desired direction or depending on the requirements of the ongoing technological process. Shut-off valves are used in various pipeline systems, be it a heating system, gas supply, steam pipelines, water supply, sewage or other engineering systems. Without fittings, it is impossible to imagine the stable operation of a variety of equipment, both industrial and domestic. Of the variety of types of fittings, valves, ball valves, gate valves and gates are most widely used. One of the main parameters of any type of shut-off valves are: the connecting diameter to the mating device, the materials from which the body and the working part are made, the closing speed. For a reliable and long service life, shut-off pipeline valves must have high strength, corrosion resistance, tightness and high reliability. With regard to the installation method, all valves are designed so that their installation does not take much time. Depending on the area of ​​use, fittings are made from various synthetic and polymer materials as well as cast iron, bronze, steel, brass, titanium and aluminum.

By appointment shut-off pipeline fittings divided into the following categories: industrial, plumbing, marine, special order. Industrial valves are divided into general industrial pipeline valves for special conditions work and special.

• Industrial pipeline fittings are used in various industries and the national economy. It is produced in series and in large quantities, it is intended for heating systems, for water pipelines, steam pipelines, city gas pipelines, etc.
• general industrial pipeline fittings for special operating conditions are used for operation at high pressures and temperatures, low temperatures, on corrosive, toxic, radioactive, viscous, abrasive and bulk media. This category of fittings includes: corrosion-resistant, cryogenic, Christmas tree, heated fittings, fittings for abrasive hydraulic mixtures and for bulk materials.
• Special fittings are designed and manufactured according to special orders; their use and application are specified by technical regulations.
• Ship pipeline valves are manufactured and used for work in special operating conditions, on river and sea vessels, taking into account special requirements for minimum weight, increased reliability, vibration resistance, as well as special control and operating conditions.
• Plumbing pipeline fittings are mounted on various household appliances: gas stoves, boilers, water heaters, bathrooms, showers, sinks, etc. These products are produced in large quantities at specialized enterprises. It has small connection diameters and is operated manually, with the exception of pressure regulators and gas safety valves.
• By special order developed and manufactured according to special orders and the presence of special technical requirements... These can be experimental or unique industrial installations. For example: fittings for nuclear power plants.

The main classes of valves

According to its functional purpose, the pipeline shut-off valves is subdivided into the following main classes:

• "Shut-off" it is used to shut off or stop the flow of working fluid or gas with a certain tightness;
• "Regulatory" it is used to regulate the flow of liquid or gas by controlling the parameters of the technological process (pressure, temperature, etc.);
• "Distribution - mixing" it is used to distribute the flow of working liquid or gas in specified directions or to mix their flows;
• "Safety" designed for automatic protection of pipelines and equipment from unacceptable overpressure by relieving excess pressure of liquid or gas,
• "Protective" (cutoff) designed for automatic protection of pipelines and equipment from unacceptable or unforeseen changes in the parameters or direction of the flow of working fluid or gas, as well as to shut off the flow;
• "Phase separating"(condensate drains, air vents, oil separators) is used to automatically separate a working liquid or gas depending on their state and phase.

In this article, we will look at shut-off valves. This class of devices is mounted on pipelines and is designed to change the flow rate of liquids or gases, up to its complete cessation. Stop valves include:

• Gate valves;
• Gates;
• Cranes;
• Valves;
• Closures.

Gate valve- this is a product of industrial pipeline valves, in which the control or shut-off element of the valve in the form of a sheet, disk or wedge makes reciprocating movements perpendicular to the axis of the flow of the working medium. This is the most common type of fittings. . Gate valves can be found at objects belonging to housing and communal services, at industrial facilities and various pipelines. Gate valves are divided into full bore, in which the seat diameter is equal to the diameter of the pipeline, and truncated, where the seat diameter is less than the diameter of the pipeline. 1).

The valve consists of such basic components. The body (Fig. 1) is made of cast iron or steel. On the rod (Pos. 6), when the handwheel (Pos. 7) rotates, the disk (Pos. 2) reciprocates. The bonnet (Pos. 5) is attached to the valve body with tie bolts and nuts (Pos. 4).

Such widespread use of valves can be explained by a number of their advantages, among them:

• simple construction;
• small face-to-face length;
• used in various operating conditions;
• small hydraulic resistance.

The last advantage of the gate valves is especially valuable when they are used in main pipelines, where a very high movement of the medium is characteristic.

The main disadvantages of valves include:

• high headroom (in valves with a sliding spindle, this is due to the fact that the full stroke of the valve is one passage diameter);
• long time required for opening or closing;
• development of sealing surfaces in the valve and in the body;
• difficulty in carrying out repairs during operation.

The industry manufactures gate valves with a rising stem or stem, and with a non-rising stem. They differ in the design of the screw pair, with the help of which the shutter moves. Gate valves with a non-rising stem have a significantly smaller size. Due to the symmetrical design, the valves can be mounted on pipelines without regard to the direction of movement of the working medium. Gate valves are wedge and parallel. This fitting is used at pressures from 2 to 200 atmospheres (bar). The nominal diameter is from 8 mm to 2 m. In air conditioning and ventilation systems, the analogue of the gate valves is a gate, which is a rectangular metal sheet moving in guides perpendicular to the central axis of the duct. Now, due to the rapid development of technology and technology, gate valves are increasingly being replaced when laying new pipelines by products for shutting off water with a circular motion of the actuator with gates or as they are often called butterfly valves.

Valve is a control pipe fittings with which it is possible to change the flow rate in the pipeline. Valves supported required pressure in the pipeline, or mixing of liquids occurs in a given proportion. The shut-off element in the device is located on the spindle. The rotational movements of the flywheel to one side or the other are converted into reciprocating movements of the spindle and the locking element. The shut-off element regulates the flow rate of the liquid passing through it. The spindle is rotated either manually, with little effort, or with the help of servo drives. Most consumers most often encounter this type of fittings in everyday life, it can be found in apartments and summer cottages or on suburban areas etc. The most common type of valve is straight-through, which is mounted on straight sections of pipelines. In apartments, valves are mounted on cold and hot water supply pipelines. The main disadvantage of valves is a sufficiently large hydraulic resistance. Direct-flow valves do not have this drawback, which are mounted in those places of pipelines where it is unacceptable to reduce the flow of liquid at its outlet. The valve arrangement is shown in (Fig. 2).

The valve also consists of a body (Pos. 1). The casings are made of cast iron, steel, brass or bronze. Cast iron valves, general technical shut-off valves, which have received a very wide application, are manufactured with flange and sleeve connections, are characterized by a low price and are readily available. Steel valves are most often used in technological processes with rigid parameters of the working environment, as well as with high requirements for reliability, are manufactured with flange connection. Brass and bronze valves are made in a sleeve design and are very often installed in heating systems, hot and cold water supply of buildings and structures. The connection of the product to the pipelines, depending on the design, is made using flanges (Pos. 8), couplings or welding. The direction of flow of the working medium is always indicated on the body of the device (Pos. 9). The regulation of the flow of the working medium is carried out using the spool (Pos. 2) mounted on the rod (Pos. 5). The stem seal (key 4) is designed to prevent fluid from flowing through the stem. In the spindle seal assembly, a stuffing box, bellows or diaphragm design can be used. The stem is rotated using a handwheel (Pos. 6). The cover (Pos. 10) is sealed with sealing gasket(Pos. 7) and is fixed to the valve body with bolts and nuts (Pos. 3). This design of the valve makes it easy to repair it during operation.

Shut-off valve (ball)- another type of shut-off pipeline equipment that has recently been very popular and has come to replace valves. The shut-off valve device is a very simple body and a shut-off element, which can be made in the form of a ball (ball) or in the form of a cylinder (cylindrical) and, less often, with a conical shut-off device. By performance, shut-off valves are divided into full bore or not full bore. A full bore ball valve has a bore equal to the connecting diameter. A non-full bore valve has a bore that is smaller in diameter than the diameter of the connecting one. The shut-off valve works in two modes, open or closed. Its main task is to block the flow of the working medium passing through it. The shut-off valve device can be seen in (Fig. 3)

The ball valve consists of a body (Item 1) made of brass or stainless steel or plastic. The ball valve (Pos. 2) is made of brass. The seats are sealed on both sides with Teflon O-rings (Key 3). After assembling the ball valve, the entire structure is closed with a nut (Pos. 4) made of brass. The stem (Pos. 5) made of brass can be used to control the position of the ball (open or closed). The stem is fitted with a handle (Pos. 6) made of steel or aluminum, which is fastened with a nut (Pos. 7).

The most widely used ball valves are made from brass and various grades of steel. These are stainless steel, molybdenum steel and common carbon steel. There are also ball valves that are made of plastic, polyethylene or polypropylene, materials resistant to aggressive environments... Plastic products have low tightness and are sensitive to mechanical impurities in the working environment. Their main difference from products made of metal is the area of ​​application. Plastic ball valves are sensitive to the high temperature of the working environment, and it is best to install them in cold water supply systems and hot water supply systems with hot water temperatures up to 65 C. Due to the large coefficient of linear expansion, about ten times more than in metals, in systems heating, these products should not be used. From the effect of high temperature on the plastic parts of the ball valve, their deformation occurs and the tightness is broken. The area of ​​application of stainless steel taps is trunk pipelines with a diameter of 50 mm or more. They are designed to work with high pressure and temperature. For domestic purposes, the use of stainless steel taps is too expensive.

Check valves Is a protective pipe fitting that prevents the backflow of liquid or gas in pipelines. Purpose and types check valves were examined in more detail

Gates it is a compact shut-off valve made of steel or special alloys, providing high tightness when closing. In this case, the flow of the working medium can be regulated so that it passes through optimal mode or completely overlap. This pipeline fittings are the simplest and most convenient in operation and have affordable price... In the gate, the regulating (shut-off) element rotates around the axis on which it is fixed. Butterfly valve is the most common type of this type of pipeline fittings. Butterfly valves according to the type of materials used for sealing the shut-off of the flow of the working medium, are used with a soft seat seal, with a metal-to-metal seal, with a Teflon coating of the overlapping parts of the valve. The device of the butterfly valve is shown in (Fig. 4)

Butterfly valve device

The butterfly valve "Butterfly" is a body (Pos. 1), which can be made of steel or cast iron. Inside the body there is a movable part, a rotary disc (Pos. 3), which rotates around its axis. The swivel disc is pressed against the rubber O-ring (Pos. 2). Thus, the flow of the working medium is blocked. For ease of installation, there are special lugs in the valve body (Pos. 4). The handle (Pos. 5) and the handle position lock (Pos. 6) are used to pivot and lock the turntable in various angular positions. You can control the position of the shutter, depending on the required applied force, using a handle, through a gearbox or using an electric drive. Such operational properties of butterfly valves "butterfly" as ease of installation and replacement of sealing elements, small construction dimensions and weight, as well as durability (up to 100 thousand openings and closings) and a relatively low price gave impetus to their widespread use in heating systems, water supply and air conditioning.

Installation methods to the pipeline

Depending on the method of connection to pipelines, the following types of industrial shut-off valves: coupling, nipple, fittings for welding, clamping, pinned, flanged, choke.

1. Coupling fittings its connection to pipelines is carried out using couplings with an internal thread.
2. Nipple fittings it is attached to the pipelines with nipples.
3. Butt weld fittings its installation to the pipeline is carried out by welding. This method of installation to the pipeline has both advantages and disadvantages. So, high-quality installation of fittings has absolute tightness in the connection, the welded seam does not require maintenance (tightening of flange connections), but it has certain problems in case of repairs when replacing fittings.
4. Tightening fittings (wafer) its attachment to pipelines is carried out using studs and nuts;
5. Flanged fittings it is connected to the pipelines using flanges. This method of fastening makes it possible to repeatedly mount and dismantle the reinforcement. Very high installation strength and the ability to operate valves in a wide range of operating pressures and diameters. The disadvantages of this method of installation include the weakening of the fasteners during operation and the loss of tightness of the joints, as well as the large weight and dimensions.
6. C apk fittings (american women) its installation to the pipeline is carried out on an external thread with a shoulder for sealing using union nuts.
7. Choke fittings attached to the pipeline with fittings.

Working medium pressure

Depending on the nominal pressure of the working medium, pipeline fittings can be divided into: vacuum, low, medium, high and ultra-high pressure.

• Vacuum(medium pressure less than 1 atmosphere)
• Low pressure(from 0 to 16 atmospheres)
• Medium pressure(from 16 to 100 atmospheres)
• High pressure(from 100 to 800 atmospheres)
• Ultra high pressure(from 800 atmospheres).

Temperature regime

Depending on the operating temperature, shut-off valves are subdivided into:

• Cryogenic(operating temperature below minus 153 ° С)
• For refrigeration technology(operating temperature from minus 153 ° С to minus 70 ° С)
• For low temperatures(operating temperature from minus 70 ° С to minus 30 ° С)
• For medium temperatures(working temperature up to 455 ° С)
• For high temperatures(working temperature up to 600 ° С)
• Heat resistant(operating temperature over 600 ° C)

Control methods

Remote control fittings does not have a direct control, but is connected to it using rods, speakers and other devices.

Drive armature control is carried out by means of an actuator (directly mounted on the valve or remotely).

Automatically controlled valves the shutter is controlled without the participation of the operator, but directly under the influence of the parameters of the working medium, on the shutter or on the sensor, or by acting on the valve drive of the control medium, as well as by signals coming to the drive from the ACS instruments.

Manual valves Control is carried out by the operator manually, remotely or directly.

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