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• Finishing
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Features of gate valves of various modifications

The performance of the same tasks can be carried out by various types of reinforcement, characterized by different principles shutter designs. So, according to the principle of the shutter, the following main types are distinguished pipe fittings: valves, gate valves, cocks, dampers, hose valves, diaphragm valves, level, flow and pressure regulators.

The wedge valve is intended only for blocking the flow of the working substance; it cannot be used to regulate the pressure.

Gate valves are an integral part of the plumbing system. Exist different types gate valves, each of which has its own characteristics, advantages and weaknesses.

Functional purpose

Depending on the type of product, it can be used to perform various functions:

• as flow regulator working environment;
• as pipeline shut-off valves;
• as pipeline shut-off and control valves.

The main purpose of valves is their use as shut-off valves - devices necessary to shut off the flow of the working medium with a certain degree of tightness.

Their similar use allows discrete (two-position) regulation of the flow rate of the working medium.

In some cases, short-term use of valves is allowed to perform the functions of shut-off and control valves.

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Structural features of gate valves

Scheme of the main elements of the valve.

Each valve type differs from other types in a number of ways. Depending on the design of the gate, the designs are divided into parallel and wedge.

The difference between wedge modifications is that their sealing rings are located at a certain angle, forming a wedge, while for parallel valves, such rings are located parallel to each other.

Wedge models are made with a solid (elastic or rigid) wedge or a two-disk composite wedge formed by 2 disks located at some angle to each other.

A parallel valve can have a gate in the form of 1 sheet or disk, or in the form of 2 disks with a spacer spring or spacer wedge located between them.

Parallel gate valves differ in cast iron. They are used as control and shut-off valves for steam, gases and water. The fittings are connected to the pipeline using flanges and bolts. Parallel gate valves with a rising spindle are shut-off valves and at the same time can be used as a gate to control the volume of water supplied. They are installed on pipelines with a diameter of at least 50 mm.

Shut-off valves can be with non-retractable (rotatable) or retractable spindle. In the first case, when opening and closing the valve, the spindle performs only a rotational movement. The lead thread is in contact with the working medium. In the second case, when opening and closing the valve, the spindle makes a translational movement. The lead thread and nut are located outside the valve cavity.

The shut-off valves are controlled by an electric or manual drive. On manually operated valves with large diameters, a spur, bevel or worm gear reducer is used to reduce the force required on handwheels.

As a rule, such shut-off valves are made with full bore, that is, the diameter of the valve passage is almost the same as the diameter of the pipeline. In some cases, to reduce the size and weight, reduce the moments and forces required to control the shut-off valves, "socket" (narrowed) valves are used.

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Structural modifications and main types of gate valves

Scheme of valve drives.

Gate valves are various types. So, according to the type of shutter, the following valves are distinguished:

• with a wedge locking element (wedge);
• with a parallel locking element (gate);
• with elastic deformation of the valve channel for the working medium (hose).

In turn, wedge modifications can be with a composite wedge, with an elastic wedge and with a solid wedge.

Knife gate valves are a type of valves in which the sealing surfaces of the gate elements are parallel to each other. Such fittings also have a number of modifications. So, single-disk sliding gate models are equipped with 1 disk, which is pressed by the sealing surface to the surface of the body seat. In the center of the disk there is a hinge, with the help of which the force is transferred from the rod to the disk. The compression can be carried out using wedge spacers installed in the housing.

Double-disk slide gate products can be both with wedge and spring spacers.

According to the way the gate moves, the valves can be of rotary type and reciprocating type. In gate fittings, sealing along the gate is carried out using spring-loaded movable saddles. There are modifications of the rotary type, which are equipped with 2 fixed disks with holes, between which a movable disk is placed. During the rotation of this disk, the working environment is overlapped.

The use of elastic elements guarantees the necessary fit of the contact surfaces of the disks.

Depending on the type of shaping of the body of the product, there can be:

• cast;
• welded;
• forged or stamped;
• combined.

Scheme of types of gate valves.

When choosing a method for manufacturing a product body, the following factors are taken into account:

• release program and technological capabilities for the production of products;
• resistance of the valve body to the working environment;
• restrictions depending on the conditions of use of the product (temperature, pressure, corrosion resistance, etc.);
• quality characteristics of the material used for the manufacture of the case.

In the manufacture of locking structures from metal, the main type of shaping of the body of products is casting. But with high strength requirements, stamping, forging, or a combined method of manufacturing the case are more preferable.

There are other classifications of locking products. So, according to the type of sealing of moving parts, they are divided into:

• self-sealing;
• bellows;
• omental.

Stuffing box gate valves - the tightness of moving parts (stem, spindle) in relation to the external environment is ensured with the help of a stuffing box seal. In bellows modifications, the tightness of moving parts is ensured by means of a bellows - an elastic corrugated shell that retains strength and density during high-cycle deformations.

According to the nature of the transfer of control force to the gate valves are:

• with progressive drive;
• with rotary drive.

By type of management:

• from the working environment;
• from hydraulic drive;
• from pneumatic drive;
• from the electric drive;
• manual through a reducer;
• manual from the flywheel.

Shut-off valves

Trumpet ( a. valving fittings, valve accessories; n. Absperrarmatur, Verschluβarmatur; f. accessoires d "arret, robinetterie; And. armadura de cierre) - devices for controlling the flow of transported materials ( natural gases, oil, etc.) in pipelines, boilers, units, tanks, etc. tech. structures; the most common pipe fittings. Fastens on pipes with the help will attach. branch pipes (coupling, flange, pin or choke) or welded. Distinguish Z. a. general technical and special destination. The most widely used in the industry received Z. a. general technical destination, edge is used in the transportation of non-aggressive liquids and gases. Z. a. specialist. intended for corrosive, aggressive or toxic media, as well as high pressures, low and ultra-low temperatures, vacuum, etc. and is made from legir. chromium-nickel steel. Main structural elements Z. a. - housing and shutter. Depending on the shape of the shutter and the nature of its movement in the body during the work of Z. a. is subdivided into taps, valves (gates), gate valves and dampers (rotary or butterfly valves). The valves are mounted on main gas pipelines, gas collection manifolds, gas collection and treatment plants, etc. The body of the crane - demountable or welded. The shape of the shutter is conical (plug valves), cylindrical and spherical (Fig. 1).
hydraulic drive; 2 - spindle; 3 - body; 4 - ; 5 - shutter ">
Fig. 1. Ball valve: 1 - hydraulic drive; 2 - spindle; 3 - body; 4 - saddle; 5 - shutter.
Distinguish between valves of equal and unequal passage (the diameter of the through passage channel of the fittings, respectively, is equal to or less than the inner diameter of the pipeline). The first have significantly less hydraulic. resistance, increased degree of tightness, reduced size and weight, allow cleaning the cavity of pipelines with a scraper and other cleaning devices; the latter are used if the increased pressure drop that occurs on them does not affect the operation. pipeline mode. In the case of underground installation, the cranes are additionally equipped with columns with an extension spindle. For tightness and to reduce friction between the valve body (with conical and cylindrical gates) and the gate, a seal is introduced. lubricant. The tightness of valves with a ball valve is ensured by packing seals. lubrication (paste) between the valve and the saddles, as well as due to the rubber rings located on the saddles. The cranes are controlled by manual mechanical, electric, pneumatic. and hydraulic drives (more economical and provide smooth and uniform rotation of the shutter). Valves are manufactured with a nominal diameter (Dy) from 15 to 1400 mm (nominal diameter of the hole used for the passage of transported materials), for a nominal pressure (Py) from 0.1 MPa to 16 MPa (the largest overpressure operating pressure at t 20 ° C, at Krom it is provided for a long time. And safe work armature) and temp-py; transported materials from -60°C to +80°C, environment from -60°C to +40°C. Promising are cranes with a welded body, a full-bore ball valve, the surface of which is covered with chromium, nickel or chromium-nickel, constantly pressed saddles, hydraulic. drive, local and remote. control, equipped with automatic emergency closing. Ball valves made by French, Italian, Japanese, German and Czechoslovak factories also found wide application in the CCCP.
Valves (fig. 2) are used in the main. to connect control and measure. devices, as well as on dead ends of pipelines, technol. piping of boilers, units, tanks and other installations.

According to the design of the body, the valves are subdivided into straight-through, angular, direct-flow and mixing valves, the valve - poppet, membrane and hose, the spindle - with its vertical and angular arrangement (in relation to the direction of the transported flow). The tightness of the valves on the saddle is achieved by lapping seals. surfaces or by placing on the gate will seal. rings made of soft metals or non-metallic. materials, along the spindle - can be adjusted by tightening the stuffing box connection. The movement of the shutter is carried out using a flywheel or actuator (pneumatic, manual mechanical, electromagnetic; the first are the most common). The valves are characterized by a relatively small stroke of the shutter, which is necessary for the complete overlapping of the pipeline section, as well as the possibility of throttling the flow; are produced in connection with high hydraulic resistance and the need to overcome when closing means. pressure from the side of the transported material c Dy up to 300, less often up to 400 mm. They operate at high pressure drops across the gate and final operating pressures - Py up to 250 MPa, as well as the temperature of the transported material from -200 to 450°C. For small pipe diameters, the most rational is the design of the valve with a shutter in the form of a conical plate, for large - flat.
Gate valves are installed at the wellhead, as well as on pipelines transporting oil products, water and steam (Fig. 3).

Depending on the diameter of the passage channel, there are equal and unequal gate valves, according to the principle of operation of the gate - with one- and two-sided force. sealing, as well as self-sealing, according to the design of the gate (large valves) - wedge and parallel. Wedge gate valves are relatively simple in design, reliable in operation, however, they are distinguished by the possibility of jamming during a sharp change in temperature, leakage due to contamination of the seals. surfaces, in addition, some difficulty is caused by fitting the wedge to the valve body. Parallel - are subdivided into gate valves with expansion wedges, self-sealing (without expansion devices), mechanical. driven discs with lubrication (the most common are the first and last). Gate valves with lubrication have an increased degree of tightness, but are difficult to manufacture and require more careful maintenance during operation. All types of gate valves are characterized by a small allowable pressure drop across the gate. Drive - manual mechanical, electric (more common), pneumatic. or hydraulic. Gate valves are produced with Dy from 50 to 2000 mm, Ry from 0.4 MPa to 16 MPa, at a temperature of the transported medium up to 450°C. The most rac. design - gate valves with lubrication, parallel gate and electric. drive.
B case large diameter, low pressures of the transported material and reduced requirements for the tightness of the shut-off valve on pipelines transporting water, oil, oil products and non-aggressive, dampers are installed (Fig. 4).


Their tightness is achieved by placing on the gate, less often in the case of rubber seals. rings. Small diameter dampers are controlled manually using a lever, large ones - using a drive (manual mechanical, pneumatic, electric or hydraulic). The dampers are characterized by relative simplicity of design and control, low metal consumption and overall dimensions, however, due to the uneven passage and the complexity of ensuring the tightness of the shutter, their use is difficult. The shutters are produced from Dy up to 2200 mm, Py up to 1 MPa, at the temperature of the transported material from -45 to +100°C. Literature: Modern designs of pipeline fittings, Edited by Yu. M. Kotelevsky, M., 1970; Andreev G. S., Stop valves, 2nd ed., L., 1974. H. M. Lebedev, G. S. Gruntenko.

Mountain Encyclopedia. - M.: Soviet Encyclopedia. Edited by E. A. Kozlovsky. 1984-1991 .

Shut-off valves are used in various industries dealing with pipelines of gaseous substances, steam, water, oil, oily substances and other liquids. Such fittings are necessary to disconnect sections of pipelines of any system, to perform installation or repair, to stop the supply of transported substances to consumers, as well as to dose the release of these substances and protect the pipeline network and its elements from overloads.

Purpose and device

The main purpose of shut-off valves is to reliably disconnect a pipeline section or other pipelines and devices associated with it from the flow of the medium transported through them, thereby ensuring the safety of the planned work. In addition to shutting off (cutting off) the medium circulating in the system, valves have other purposes. With its help, you can regulate, distribute, mix and remove the used medium.

In accordance with the design of the pipe, the type and parameters of the medium flow, the necessary shut-off, control and discharge devices are selected. For example, they must correspond to the pressure in the system, the type and temperature of the medium, design features pipelines (diameter, type of connections) and meet all safety requirements. By appointment, locking devices are divided into several groups.

• General purpose. It is used on water and steam pipelines, in gas lines of city networks and heating systems.
• Special Purpose. Used for high pressure, as well as in cases of low or high temperatures, toxicity, viscosity, corrosivity, radioactivity and abrasiveness of transported substances.
• Target armature. It is intended for individual cases provided for by the technical regulations.
• Plumbing. Fittings of small diameters for home appliances.
• Sudovaya. It is equipped with marine and river boats are produced taking into account specific operating conditions.
• Unique. It is produced according to special orders for industrial and experimental installations.

There are such types of locking devices:

• gate valves with cast iron and steel bodies;
• shut-off or shut-off and control valves;
• cranes of various types and devices;
• butterfly valves;
• control valves;
• safety and protective products.

All listed locking devices are similar in design. They are a hermetically sealed housing with a locking unit located in it. This unit must hermetically close the pipeline on which it is installed, dividing it into parts - sections before the valve along the medium and after it. The composition of the shut-off assembly includes two main working elements: the saddle and the mechanism of the shut-off body. These two devices, in contact with their sealing surfaces, create an obstacle to the movement of the medium used in the pipeline. In addition to the shut-off part, the fittings have details of connection with the pipeline: flanges, threaded pipes, smooth pipes for a welded joint.

Classification

All pipeline fittings are classified in several categories depending on the scope, functionality, design features, material, environmental parameters, method of fastening.

By Application

Several types of fittings for application are considered.

• Shut-off. The most numerous class of devices, accounting for approximately 3/4 of all fittings used. It is used to completely turn off the flow of the medium in the pipeline, as well as its start-up if necessary. This includes: gate valves, valves, taps produced for pipelines various diameters, working environments and parameters. The scope of such devices is quite wide: from valves for pipelines of steam, water, gas to conventional valves for heating systems and kitchens.

• Regulatory. This type of device includes all kinds of control valves, which are called at manufacturing enterprises medium pressure regulators, liquid level in vessels, pressure drops between different media, as well as throttling valves. Control valves are not considered purely shut-off bodies, therefore they are usually used with a shut-off assembly consisting of gate valves or valves installed both before and after the regulator.

• Safety. This type of device provides protection for steam pipelines, water pipelines, gas pipelines and other pipelines with the equipment located on them from excess pressure in excess of the permissible pressure by automatically dumping part of the working medium. Safety fittings include the following devices: safety valves, IPU (pulse safety devices), bursting discs and medium bypass valves.

• Protective. It is used to protect pipelines and equipment from breakdowns and accidents when the parameters of production processes are unacceptable for them, as well as to prevent a change in the direction of the flow of the working medium. Unlike safety valves protective devices liquidate emergencies without discharge of the working medium from pipelines, acting only on shutting off the movement of the working medium. These devices include non-return and shut-off valves.

• Distribution-mixing. Such fittings are also called three-way or multi-way. For example, it includes three-way valves and distribution valves. Devices are used for mixing media or distributing work flows in directions.

• Control. Designed to control the liquid level in vessels and boilers, used as shut-off valves for instrumentation. These are various taps and valves for pressure gauges, test and drain valves and level indicators.

• Phase separation. It is used to separate working media in different states and phases. These fittings are, for example, oil separators, condensate and air traps.

It should be noted that shut-off valves (gate valves, taps, valves) should only be used in two operating positions - “fully open” or “fully closed”. Most of these devices are not intended for operation as control or throttling valves. Otherwise, it quickly fails: the seats are worn out, the valve gaskets are deformed, the fittings become loose, they can no longer keep the flow of the working medium in a locked state. Spherical reinforcement can be called some exception to the rule: its opening angle does not have such a destructive effect on density. For ball devices, the most important thing in extending their service life is to clean the used working medium from solid abrasive impurities that erase the balls.

For high pressure drainage and purge systems, two locking devices are used on each line, located side by side. One of them (the first one along the medium) is considered shut-off, and the other is regulating. With a short-term purge of the drainage lines, the shut-off valve opens first, and then the control valve. After purging, the valves are closed in the reverse order (the control valves are closed first). This arrangement ensures a long service life of the shut-off valve.

Gate valves are used in engineering and industrial pipeline networks. These can be water pipes, steam pipes, heating and sewage systems. Gate valves, depending on the type of shutter, are:

• wedge mounted on sewers and water pipes for various purposes;
• disk, used for pipelines of large diameters and low pressures of the working medium, they are often called dampers;
• parallel (two-disk), characterized by high reliability, they are installed in a wide pressure range from two to two hundred atmospheres and working environments with elevated temperatures.

A valve is a locking device in which the movement of the shutter occurs due to a simple threaded pair. The flywheel stem is connected to the gate or valve by means of a clamp. When the handwheel is rotated to open, the check valve stem is pulled through the clamp. Often these devices are used as control valves, although they are classified as shutoff valves. The fact is that it is not always rational to install expensive control valves. Cranes are used in different areas, they are familiar to many from everyday life: they overlap the lines of hot and cold water in the bathroom and kitchen, gas supply to the stove, plumbing to the hose for watering the garden and other devices. They have the simplest design, but this does not make work with their repair easier.

By connection method

According to the design features of the connecting parts, pipeline fittings can be divided into two large groups:

• flanged;
• flangeless.

The specific list of flange-type fittings is limited only by the difference in the shapes of the flanges themselves.

They are:

• round;
• square (rectangular);
• triangular.

The most common fittings with round and square flanges. Other forms are rarely used or not considered at all in the design of new production facilities. Square flanges are used for media with limited maximum pressure values ​​- no more than twenty atmospheres. The main shape of the flanges remains round: it is less time-consuming to manufacture, and in terms of reliability it has a tolerance for both low pressures and high ones.

The circle of flangeless fittings is more extensive in terms of the difference in the ways of its connection to pipelines, branch pipes of vessels and containers.

This includes fittings:

• welded;
• connected using couplings;
• choke;
• tsapkovaya.

It should be noted that all the above types of connections of locking devices with pipelines, except for welded ones, are detachable. Reinforcement connected by welding, for replacement or repair, you only have to cut it out with the help of a grinder, gas burner or a hacksaw for metal in domestic cases. In choke, coupling and pin fittings for fastening connecting elements carving is used. The tightness of the joints of flange locking devices is provided by flanges with gaskets or sealing rings laid between them. There are some other devices to improve the tightness and strength of flange connections (protrusions, chamfers, spikes and annular selections).

Materials and accessories

The materials used for the manufacture of valves and components must comply with the general specifications in accordance with the standards of the Central Design Bureau of Valve Engineering (TsKBA) “Pipeline valves. General technical conditions”, which came into force in January 2006, as well as current national standards and industry specifications. The main criterion in choosing the material for the body of any valve is its strength. The body is the basis for installing all other parts into it. It is like a foundation in construction - a supporting structure for the whole building.

The bodies of most pipeline locking devices are made of cast iron or steel. Sometimes used for this and others metallic materials: on sale there are bronze, copper, aluminum and brass taps and valves for household appliances. Reinforcement made of non-ferrous metals and their alloys has a good feature - it is not subject to corrosion and has a good appearance.

The most economical material for fittings is plastic, which combines under its common name products made of PVC (polyvinyl chloride), polypropylene, polyethylene and other artificial alloys of plastic material. But such fittings cannot withstand high pressure and temperatures, as they are not durable. But for pipes of small diameter and low pressures, this is a very suitable alternative to metal products. In addition to low cost, plastic pipelines and fittings are valuable for their resistance to corrosion - the main scourge of steel devices of the same type.

Malleable, gray or high-strength cast iron is used for casting valve bodies, depending on the area and conditions of use of a particular product. Due to their brittleness, fittings with a cast-iron body are not used at high pressures in pipelines, as well as where water hammer and sudden temperature changes are possible. In such situations, the cast iron housing can simply burst.

Steel cases are made of various grades of steel: alloyed, heat-resistant and carbon. Stainless steel with high resistance to corrosion is used for the manufacture of valve bodies that are installed on pipelines with aggressive substances or have a particularly clean working environment. Cases made of heat-resistant steel are used for fittings operating at elevated temperatures of the working medium. The use of a particular material, as well as the design and type of flange, are determined by a number of factors, the main of which are the following:

• conditional diameter of pipelines;
• working environment pressure;
• flow direction;
• temperature conditions.

The valve closure is often made from the same material as the body, but more often it is made from a different metal, based on high wear resistance and working environment parameters. The material of the sealing surfaces must ensure the tightness and durability of the valve.

The sealing material is:

• metal products in the form of rings with corrosion resistance, anti-friction properties, well processed (steel, brass, bronze, monel);
• deposits from various hard alloys: stellite (cobalt alloy), sormite (iron-based alloys);
• non-metallic products (rubber and rubber-metal rings, polymer seals);
• sealing packings made of material of plant origin (cotton and linen fiber), talc, fiberglass;
• fluoroplastic and graphite for stuffing box seals in aggressive and high-temperature working environment;
• sheet rubber, paranit and fluoroplast for gaskets.

Cast iron and steel fittings equipped with flanges have undeniable advantages in terms of tightness, maintainability and strength of the pipeline network compared to flangeless ones. But the mass and dimensions of such reinforcement sometimes reach large values ​​(in tons and several meters, respectively). To this, you still need to add control devices (handwheel, electric drive or pneumatic drive, hung on fittings). Flanges lead to increased metal consumption and labor intensity in their manufacture.

Replacement and installation

The process of installing or replacing valves should be approached responsibly. There is a wide variety of such valves, which differ from each other in appearance, the device of the shutter mechanism, the method and mechanism of control, and the features of installation on the pipeline. It is necessary to choose a locking device that is suitable for this type of pipeline, this working environment and its parameters. And also make sure that the locking device can be installed in terms of connecting devices. Pipelines and fittings to them must correspond to each other according to the following indicators.

• Same sectional shape. For a round pipe, fittings are needed that have round section. This form of gate valves and other types of fittings is preferable. Pipelines rectangular section are found in ventilation systems and furnace business, where slide or plate valves are used.
• Same diameter. The diameter of the locking device must be fully consistent with the diameter of the pipeline to which it is attached. The passport data of the valve, valve, regulator and pipelines always contain information about this. In addition to the passport (instruction), data on the diameter of the devices are applied to the body of the product in accordance with the requirements for marking fittings. For example, the marking indicates Dy = 150, which means that such fittings are suitable for a pipeline with a diameter of 150 mm.
• Connecting parts of the pipeline and the installed locking device have all the possibilities of their reliable connection. This includes: the identity of the flanges in shape and size, the coincidence of the mounting holes, the diameters of the threaded connections, the correspondence of the external thread of the fastened fittings internal thread coupling, union nuts and the like.

You should know the basic rules for installing or replacing fittings on pipelines, which you cannot do without and even start work.

• Any repair or installation work is carried out only on a disconnected section of the pipeline, in which there is no working medium, no residual high temperature, no pressure. The drains and air vents on the line are open, and safety signs are hanging on the shut-off fittings on both sides of the disconnected section being repaired, excluding their erroneous opening.
• Be sure to pre-installation preparation of the connecting parts of the fittings and pipelines: they are cleaned of possible dirt and rust, and the welded joints are cleaned to a metal shine and prepared for the weld. During cleaning, you need to pay attention to the absence of any hidden defects in flanges, cracks, shells and other flaws that prevent the continuation of work.

• Installation of fittings should be carried out only on flat and straight sections of pipes. It is unacceptable to install it on bends, as this will lead to a decrease in the tightness of the joints.
• For heavy gate valves and gate elements, additional support structures and lifting devices must be provided in order to avoid accidents during work or breakage of devices and sealing elements.
• Bolts and other fasteners are tightened using special tool. The tightening of the flange studs must be uniform and according to the following rule: the nut is tightened at one end of the flange, and then at the opposite end so that the flanges do not warp.
• Welding are made only on fittings in which the shutter is in the open state.

Such sections can be, for example, jumpers between two or more lines with the same substance in pipelines. When these sections are connected during operation, the fitting is first fully opened, the direction of flow in which is opposite to that expected, and then the second device is carefully opened, corresponding to the direction of the medium. Here are some more important recommendations that are useful when replacing or installing certain types of fittings.

• All fittings intended for installation must be inspected in advance for tightness and adjustment of all internal devices.
• In flanged connections, the fixing bolts must be periodically tightened. It is impossible to immediately tighten them strongly, since you can overtighten the connection, as a result of which the gaskets will become unusable.
• When assembling the butterfly valves, slightly open the valve disc.
• For tight connection of ball valves, it is necessary to use special tapes wound around the threads of the joints.
• It is better to install locking devices in such places that they always have free access for quick shutdown, control, inspection and repair.

During installation, attention must be paid to the conformity of the installation of the valve with the direction of the medium flow. Recently, on the bodies of gate valves, valves, taps and other locking devices, the direction of the working media has been indicated with an arrow. For pipelines where the possibility of a two-way flow of liquid, steam and other substances with high pressure is provided, two shut-off valves with different directions of the working flow should be installed.

Welding work on fittings and pipelines should be carried out only by experienced specialists. Independent attempts to weld taps, valves and gate valves, as a rule, end in poor quality results and constantly arising problems at the welding points (fistulas, cracks). And the appearance of such "homemade" leaves much to be desired. But to change the faucet or faucet in the bathroom - a real owner can take up this business without fear.

For an overview of the installation of valves, see the following video.

Shut-off valves for pipelines are a means of dividing the pipeline network into separate local sections and regulating the pressure in them, depending on their purpose.

This equipment is designed to completely close/open the flow of liquids of various nature in the pipeline in accordance with the requirements of technological processes. Such devices include shut-off valves, gate valves, rotary valves and taps. In turn, shut-off and control valves play the role of a flow regulator and create tightness in the pipeline medium.

Stop valves of all types are intended for use in the following environments:

• liquid and gas-liquid;
• water;
• vaporous.

For the most part, such equipment is designed to operate only in two positions: "open" or "closed" and, most often, are not used in intermediate positions.

According to their purpose, the fittings are divided into the following types:

• shut-off - to shut off the flow of the transported medium with the main condition - tightness;
• regulating - to establish a certain flow rate of the working medium by changing the nominal section of the pipeline, as a rule, it is controlled by an independent source of energy;
• distribution - division of the flow in the necessary directions, as well as for mixing different flows;
• safety - to prevent exceeding the permissible parameters of pipelines and vessels in terms of pressure by dumping the products being pumped up to stop the flow;
• phase separation - used to separate the product into various fractions and states, these include oil separators, condensate and moisture traps.

The use of shut-off valves in sewerage systems is associated with the need to turn off its individual sections for repair.

For pipelines

Product transfer, to be an effective means of transportation, is carried out over long distances at high pressure and at high speed. Therefore, special requirements are imposed on the selection of the actual pipes and valves - gate valves, valves, butterfly valves.

It is selected according to technical standards, with design pressure, viscosity of the medium, differences in internal and outdoor temperature. The degree of pumping automation also matters.

In trunk systems plumbing systems The pumped liquid always contains a certain amount of aggressive components. Therefore, chemically resistant materials are used for fittings. These properties are fully possessed by cast iron, from which all types of valves for pipelines are made.

They are used in high and low pressure pipelines and for pumping various media. The same material is most popular in the manufacture of pipeline fittings for oil pipelines.

On main pipelines, shut-off valves with dimensions of 8 - 2000 millimeters are used.

Gate valves are controlled manually using flywheels, and in hard-to-reach places - using an electric drive remotely.

Most cast iron gate valves are designed with flange mechanisms and can be produced in various designs:

1. Gate valves - with a movable or fixed stem;

, in which there is a flat gate with a hole corresponding to the size of the pipe. Two types of drive are used for control: manual for units located in an accessible place, and remote, if the valve is installed in a closed space.

The manual drive consists of a handle in the form of a steering wheel, a screw pair and a rod attached to the gate. When the handle is rotated, the screw pair converts the rotational movement into a translational one, which through the rod drives the gate into the right direction. When the hole in it coincides with the hole in the pipe, the fluid flow resumes.

1. Wedge - a highly effective type of valves for pipelines. The shape of the locking element makes it possible to ensure the maximum tightness of the closing of the lock and the seat, which increases the quality of the overlap.

Lifting the valve moves the wedge relative to the seat, as a result of which its hole is aligned with the hole in the stationary part, ensuring the passage of the working medium. Rotation can be done manually or using a remote control.

1. Parallel.

Such devices are designed to operate at a pressure of 2 - 200

atmospheres.

The working medium and the locking elements of the device in the form of two plates are located in the chamber. The gate plates are attached to the actuator stem. When it rotates, they open, passing water or steam through the pipeline.

All presented valves have a number of common parameters, including:

1. Connection to the product pipeline is made using flanges, couplings or welding.
2. Gate valves are not used to adjust the pressure in the pipeline, but only close or open it in extreme positions.
3. Valve bodies are made of cast iron by casting, less often - of steel.
4. In all types of these fittings, sealing devices made of rubber, paronite, cardboard, etc. are used.
5. Depending on the availability of the device, a manual drive is used in the form of a flywheel or remote control using an electric drive.

Flanged valves for pipelines are used not only in water supply networks, but also when pumping oil products or other liquid media.

IN distribution networks on pipelines DN100 and less, valves and taps with coupling connections are often used. Such devices are less overall and technologically advanced during installation. Connections are made by screwing onto the thread of the mating part.

The tightness of such a joint is ensured by the use of various sealants: flax fiber, FUM tape (fluoroplastic sealing material), sealing cords and silicone sealant special purpose. Such a connection is less reliable than a flanged one, but the elimination of leaks on it is faster and easier.

Shut-off coupling valves for pipelines are used on in-house distribution networks with dimensions less than DN 50 at a pressure in the pipeline from 0.6 atmospheres.

Water stop valves for distribution networks

Such products various kinds and destinations are intended to deliver water from the supply tank to the end point of consumption. Its main purpose is to close or open the flow of fluid in the pipeline, as well as to regulate the pressure in the network. Simply put, any of these mechanisms, be it a faucet or a valve, allows you to cut off or resume the water supply.

The device of shut-off valves is quite simple. The basis is a cast-iron or brass pipe. A valve is inserted into it, which can partially or completely block the lumen in the pipe, which leads to a change in pressure in the pipeline or a cessation of flow. The mechanism is controlled by a lever crane of arbitrary shape.

Functional purpose of devices

Fittings on the water supply network are installed not only in every house, but also in every apartment. It serves to regulate the pressure in the domestic plumbing and distribute water to all areas of the apartment, where it is provided for by the project.

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Such devices are also installed in industrial buildings and premises where the use of water is provided for by the production technology, as well as for sanitary needs. For this purpose, pipes made of special materials other than those used in residential construction are used.

Shut-off valves for water supply are functionally designed to lock the liquid in the pipe and, if necessary, supply it to the destination in the right amount.

The material for the manufacture of locking mechanisms can be various substances, but more often than others it is such as:

1. Cast iron of various modifications.
2. Brass.
3. Stainless steel, capable of painlessly passing chemically active liquids, which are also often pumped through pipelines.

On the advantages and disadvantages of various classifications of devices

Due to their high performance and aesthetic appearance, brass or stainless steel valves are the most popular at present. Such products in the water supply network can serve up to a decade and a half.

Despite this, research to improve the resistance of water fittings using new materials is ongoing. As a result, devices polymer materials, which can be operated indefinitely long time, unless disloyal methods of mechanical action are applied to them.

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Otherwise, at the junction with various materials wear will be different. And the overall service life of the system is determined by the most rapidly wearing material.

One of the advantages of plastic water pipes is the fact that they do not have threaded connections. Elements are joined by soldering on special equipment or using adhesives. Such dockings are as reliable as possible and can only be broken using brute force.

For main networks for water, they are mainly used polyethylene pipes size 820 - 1020 millimeters. Used with them plastic fittings for water supply systems. Such pipes easily withstand the pressure accepted for water, in most cases, no more than 20 atmospheres.

Metal pipes are connected by the same fittings. But since threaded connections less reliable, sealing materials and sealants must be used.

Consider the types and classifications

There are many designs of valves and faucets for plumbing. The most popular of them are:

1. Cranes with crane box.

The flow of water through the pipe is blocked when the stem is twisted by its action on the rubber gasket, which sits on the saddle and blocks the passage. Weak point in this system is a gasket that periodically has to be replaced. The presence of a spare gasket in the house with such taps is an objective necessity. The bodies of such cranes are made of brass, less often - of cast iron.

1. Faucets and valves with ceramic inserts

This design of water shut-off valves has already become familiar due to the high reliability of the checkpoint.

Water is passed from the pipe by turning the handle at an angle of about 180 degrees. In this case, the openings in the two ceramic plates are combined, and a passage for water from water pipe. Due to the high surface strength of the plates, their wear is very slow, and the use of a backing rubber gasket in the lower (fixed part) of the bushing crane provides wear compensation and tightness of the connection. Details of the crane box (and the crane itself) are made of brass.

1. Ball Valves.

As a locking element in such devices, a ball made of brass with a high surface quality is used. It is processed by polishing using diamond paste and then nickel or chrome plating. The hole in the ball corresponds to the size of the passage. When the stem handle is rotated, the ball rotates 90 degrees and closes/opens the hole. Wear-resistant Teflon rings are used as seals. Not intended for pressure regulation.

In addition to these types of valves, many others are produced:

• cranes for dumping air congestion in the heating system;
• emergency pressure relief valves installed on vessels;
• valves for adjusting the pressure in the internal water supply system.

To shut off the pipeline emergency cases ball valves are used.

Technology and production methods

Manufacture of pipeline fittings is a complex technological process that includes a number of sequential steps that ensure the production of reliable and salable products.

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The technology for the production of valves for pipelines provides for the following steps:

1. Marketing on the market of relevant products in order to determine the effective (sellable) range of products.
2. Design and survey work to create models and types of effective products, both in terms of quality and manufacturing costs.
3. Development of production technology, definition optimal composition equipment.
4. Development of methods for effective non-destructive control of product quality.
5. Development effective advertising its products.
6. Logistics and sales of products.

The technology for the production of valves for pipelines can be represented as follows:

1. Purchase of raw materials for production. Input quality control of raw materials and components.
2. Manufacture of blanks for the manufacture of fittings by casting from cast iron, brass and other suitable materials.
3. Heat treatment of cast blanks to give them the necessary mechanical properties.
4. Machining of working surfaces up to required parameters flatness and surface finish. Turning threaded connections.
5. Applying a protective coating by electroplating. Nickel plating is usually applied.
6. Assembly of water fittings using parts of our own production and components purchased through cooperation.
7. Final quality control finished products and transfer to the warehouse finished products. It should be noted that intermediate control operations during the manufacture of reinforcement are carried out after each technological step. For example, after casting and electroplating, ultrasonic testing is mandatory to detect pits and other discontinuities.
8. Sales of finished products.

Enterprises that intend to sell their products abroad need to certify them according to ISO 9001. It is important that, in accordance with the requirements of this standard, not only final result(products), but also the entire process of organizing production, starting from the workflow.

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Technical documentation

Production of shut-off valves for pipelines and oil pipelines in part general requirements regulated by GOST R 53673-2009. The operating rules and features of the installation are considered by a number of SNiPs in terms of the relevant requirements.

Entries

Shut-off valves

In the heading "Accessories" we will consider shut-off valves. Without shutoff valves, it is impossible to imagine any piping system. Shut-off valves – this is a pipe fitting that has found wide application and usually accounts for up to 80% of the total number of products used. The name "shut-off valves" refers 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 right direction or depending on the requirements of the ongoing technological process. Shut-off valves are used in various pipeline systems, whether it is a heating system, gas supply, steam pipelines, water supply, sewerage or other engineering systems. Without fittings, it is impossible to imagine the stable operation of a variety of equipment, both industrial and household purpose. From a variety of types of fittings greatest application received valves, ball valves, gate valves and gates. 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 is made and working part, closing speed. For reliable and long term operation, shut-off pipeline valves must have high strength, corrosion resistance, tightness and high reliability. Regarding the method of installation, 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 polymeric materials, as well as cast iron, bronze, steel, brass, titanium and aluminum.

By appointment shut-off pipeline fittings is divided into the following categories: industrial, sanitary, ship, by special order. Industrial valves are divided into general industrial pipeline valves for special working conditions and special ones.

• Industrial pipeline fittings are used in various branches of industry and national economy. It is produced serially and in large quantities, it is intended for heating systems, for water pipes, steam pipelines, city gas pipelines, etc.
• general industrial pipeline valves for special operating conditions are used for operation under conditions of high pressures and temperatures, low temperatures, on corrosive, toxic, radioactive, viscous, abrasive and loose media. This category of fittings includes: corrosion-resistant, cryogenic, fountain, 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 produced and used for operation 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 operation conditions.
• Plumbing pipeline fittings are mounted on various household appliances: gas stoves, boilers, columns, bathrooms, showers, sinks, etc. These products are produced in batches in huge quantities in specialized companies. It has small connection diameters and is operated manually, with the exception of pressure regulators and gas safety valves.
• By special order designed and manufactured according to special orders and availability of special technical requirements. It can be experimental or unique industrial plants. For example: fittings for nuclear power plants.

The main classes of valves

In my own way functional purpose pipeline shut-off valves subdivided into the following main classes:

• "shut-off" used to block or stop the flow of a working fluid or gas with a certain tightness;
• "regulatory" used to control the flow of liquid or gas by controlling the process parameters (pressure, temperature, etc.);
• "distributive-mixing" used to distribute the flow of a working fluid or gas in given directions or to mix their flows;
• "safety" intended for automatic protection pipelines and equipment from unacceptable excess pressure by relieving excess liquid or gas pressure,
• "protective" (cut-off) designed to automatically protect pipelines and equipment from unacceptable or unforeseen changes in the parameters or direction of the flow of the working fluid or gas, as well as to turn off the flow;
• "phase separation"(condensate traps, air vents, oil separators) is used for automatic separation of the working liquid or gas depending on their state and phase.

In this article, we will consider shutoff 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. Shutoff valves include:

• gate valves;
• Valves;
• Cranes;
• valves;
• shutters.

gate valve- this is a product of industrial pipeline shut-off valves, in which the regulating or shut-off body of the valve in the form of a sheet, disk or wedge performs reciprocating movements perpendicular to the axis of the flow of the working medium. This is the most common type of reinforcement . Gate valves can be found at facilities 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 Gate valves are mounted on pipelines with a connecting diameter of more than 50 mm, where it is necessary to smoothly adjust the flow rate to prevent occurrence. The valve device is shown in (Fig. one).

The valve consists of the following main components. The housing (Fig. 1) is made of cast iron or steel. On the rod (Pos. 6), when the flywheel (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 design;
• small construction length;
• used in various operating conditions;
• little hydraulic resistance.

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

The main disadvantages of valves include:

• high headroom (in rising stem valves, this is due to the fact that full speed shutter is one passage diameter);
• long time required to open or close;
• development of sealing surfaces in the gate and in the housing;
• difficulty in carrying out repairs during operation.

The industry produces gate valves with a rising stem or stem, and with a non-rising stem. They differ in the design of the screw pair, with which the shutter moves. Gate valves with a non-rising stem have a significantly smaller construction size. Due to the symmetrical design, the gate 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, an analogue of gate valves is a gate, which is a rectangular a 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 movement of the actuating element with gates, or as they are often called butterfly valves.

Valve is a control pipe fitting, with the help of which it is possible to change the flow in the pipeline. With the help of valves, the necessary pressure in the pipeline is maintained, or liquids are mixed in a given proportion. The locking element in the device is located on the spindle. The rotational movements of the flywheel in one direction or the other are converted into reciprocating movements of the spindle and the locking element. The locking element regulates the flow of fluid 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 valve in everyday life, it can be found in apartments and cottages or in suburban areas, etc. The most common type of valve is a through valve, which is mounted on straight sections of pipelines. In apartments, valves are mounted on the supply pipelines of cold and hot water supply. The main disadvantage of valves is a rather large hydraulic resistance. This disadvantage is not present in direct-flow valves, which are mounted in those places of pipelines where it is unacceptable to reduce the flow rate of the liquid at its outlet. The valve device is shown in (Fig. 2).

The valve consists of a body (Pos. 1). Cases are made of cast iron, steel, brass or bronze. Cast iron valves are general technical shut-off valves, which have received a very wide application, are made with flange and socket connections, are characterized by a low price and are easily accessible. Steel valves are most often used in technological processes with strict 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 coupling design and are very often mounted in heating systems, hot and cold water supply of buildings and structures. Connection of the product to pipelines, depending on the design, is carried out using flanges (Pos. 8), socket connections or welding. The direction of flow of the working medium is always indicated on the body of the device (Pos. 9). The flow of the working medium is adjusted using a spool (Pos. 2) mounted on the stem (Pos. 5). The stem seal (Item 4) is designed to prevent fluid from flowing over the stem. In the spindle sealing assembly, a stuffing box, bellows or membrane design can be used. The rotation of the rod is carried out using the handwheel (Pos. 6). The bonnet (Pos. 10) is sealed with a gasket (Pos. 7) and fastened 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 replaced 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 most rarely with a conical locking device. By performance, shut-off valves are divided into full bore or non-full bore. A full bore ball valve has a through hole equal to the diameter of the connecting one. A non-full bore valve has a through hole smaller in diameter than the diameter of the connecting one. The shut-off valve operates in two modes, open or closed. Its main task is to block the flow of the working environment passing through it. The stopcock device can be seen in (Fig. 3)

The ball valve consists of a body (Pos. 1) made of brass or stainless steel or plastic. The locking element ball (Pos. 2) is made of brass. Both sides of the seat are sealed with Teflon O-rings(Pos. 3). After Assembly ball valve the whole structure is closed with a nut (Pos. 4) made of brass. With the help of a rod (Pos. 5) made of brass, you can control the position of the ball (open or closed). A handle (Pos. 6) made of steel or aluminum is mounted on the stem, which is fastened with a nut (Pos. 7).

The most widely used ball valves are made of brass and various steel grades. This stainless steel, steel with molybdenum content and ordinary 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 scope. Plastic ball valves are sensitive to high temperatures of the working environment, and they are best installed 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, they are deformed and the tightness is broken. The scope of stainless steel taps is main pipelines with a diameter of 50 mm or more. They are designed to work at high pressure and temperature. For domestic purposes, the use of stainless faucets is too expensive.

check valves- this is a protective pipe fitting that prevents the reverse flow of liquid or gas in pipelines. Purpose and types check valves have been considered in more detail

closures is a compact shut-off valve made of steel or special alloys, which ensures high tightness when closed. In this case, the flow of the working medium can be adjusted so that it passes in optimal mode or cover completely. This pipeline fitting is the most simple and convenient in operation and has affordable price. In the shutter, the regulating (shut-off) element rotates around the axis on which it is fixed. Butterfly type butterfly valve is the most common type of this type of pipe fittings. Butterfly valves according to the type of materials used to seal the flow of the working medium, are used with soft saddle seal, with metal-to-metal seal, with Teflon-coated closing parts of the valve. Device butterfly valve type "Butterfly" is shown in (Fig. 4)

Butterfly valve device

Butterfly gate valve is a body (Pos. 1), which can be made of steel or cast iron. Inside the housing there is a movable part, a rotary disk (Pos. 3), which rotates around its axis. The turntable 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 knob (Item 5) and knob position lock (Item 6) is used to rotate and lock the rotary disc in various angle positions. To control the position of the shutter, depending on the required applied force, you can use the handle, through the gearbox or with the help of electric drive. Such operational properties butterfly dampers, 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 relatively low price gave impetus to their mass application in heating, water supply and air conditioning systems.

Ways of installation to the pipeline

Depending on the method of connection to pipelines, the following types of industrial stop valves: coupling, nipple, welding fittings, coupling, pin, flange, nipple.

1. Coupling fittings its connection to pipelines is made by means of couplings with an internal thread.
2. Nipple fittings it is attached to the pipelines with nipples.
3. Weld fittings its installation to the pipeline is carried out by welding. This method of mounting to the pipeline has both advantages and disadvantages. Thus, high-quality installation of fittings has absolute tightness in the joint, the weld does not require maintenance (tightening of flange joints), but has certain problems in case of repair when replacing fittings.
4. Coupler fittings (wafer type) its fastening to pipelines is carried out with the help of studs and nuts;
5. Flanged fittings it is connected to pipelines by means of flanges. This method of fastening makes it possible to repeatedly assemble and dismantle the reinforcement. Very high mounting strength and the ability to operate valves in a wide range of operating pressures and diameters. To disadvantages this method installation should include the loosening of fasteners during operation and the loss of tightness of the joints, as well as a large mass and dimensions.
6. C apical fittings (american) its installation to the pipeline is carried out on an external thread with a collar for sealing with union nuts.
7. Choke fittings attached to the pipeline with fittings.

Medium pressure

Depending on the conditional pressure of the working medium, pipeline valves 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, valves are divided into:

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

Control methods

Armature for remote control does not have a direct control, but is connected to it using rods, speakers and other devices.

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

Valves with automatic control the shutter is controlled without the participation of the operator, but directly under the influence of the parameters of the working environment, on the shutter or on the sensor, or by acting on the actuator of the valve of the control medium, as well as by signals coming to the actuator from the ACS devices.

Valves with manual control The control is carried out by the operator manually remotely or directly.

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