Hello dear readers. Everyone has probably experienced a pipeline break. Moreover, most often this happened in places where the so-called wedge valve was installed. What it is?
Diameters and dimensions
The overall and installation dimensions of wedge valves are determined by GOSTs and TUs and differ for products made from different materials for different purposes. So, for products 30ch925brM and 30ch39r the parameters are given in the table.
The model range of wedge gate valves includes products with a nominal diameter (nominal diameter of the passage opening) of 15...2000 mm.
Manufacturers and average prices
Among the manufacturers we can distinguish the following domestic and foreign companies (near abroad):
- Agrokomplekt, JSC (Russia, Podolsk);
- Armalit, OJSC (Russia, St. Petersburg);
- Blagoveshchensk Reinforcement Plant, JSC (Russia, Blagoveshchensk);
- Budava, JSC (Lithuania, Kaunis);
- Pipeline Elements Plant, JSC (Russia, Bolshoi Istok);
- Ivano-Frankivsk Reinforcement Plant, JSC (Ukraine, Ivano-Frankovsk);
- IKAR, Kurgan Pipeline Fittings Plant, LLC (Russia, Kurgan);
- InterArm, group of companies (Russia, Moscow).
For gate valves made of ferrous metals, the price index for the indicated manufacturers is 1.9777 rubles/+12.90% (according to Infogeo.ru).
For foreign manufacturers (Tecofi, HAWLE, BRANDONI, UKSPAR and others) prices range from 800...170,000 rubles, depending on the brand, characteristics and purpose of the product.
Installation
Basic rules for mounting and installing a wedge valve:
- first verify the suitability of the product for installation according to technical characteristics and actual performance;
- monitor the partially open position of the shutter during the process;
- if the nominal diameter of the device is more than 100 mm, use additional supports;
- To move the product using lifting and transport equipment, secure it only to the mounting lugs;
- for underground installation, arrange a base of rammed soil without sharp fractions, the thickness of the base for channelless laying of communications is at least 200 mm;
- After installation, check the operability of the pipeline section, first at minimum, then at nominal and at maximum permissible pressure. During testing, the shutter must be fully lowered or raised.
The selection of gaskets for connecting the valve flanges to the pipeline flange should be carried out according to the requirements.
The permissible forces when tightening the nuts are given in the table “Tightening torques for hex nuts flange connection».
| Nominal diameter (DN) | Nut/bolt, nominal thread diameter | Moment, Nm |
| 15…32 | M10 | 15…30 |
| 40…65 | M12 | 35…50 |
| 80…100 | M16 | 75…100 |
| 125…150 | M16 | 80…120 |
| 200 | M20 | 150…200 |
| 250…400 | M24 | 340…410 |
| 500 | M27 | 340…410 |
For a better understanding of the installation, control and connection process, a video is presented about installing a valve with a large nominal diameter in an underground utility well.
The wedge valve plays an important role in ensuring reliable operation of pipelines that facilitate the movement of various media. The mechanism of the device and the method of operation are highly efficient and functional.
What is a wedge valve?
Pipeline fittings are widely used in the organization of technological processes, the operation of energy systems and processing complexes. Wedge valves are a type of valve that has some technical features.
The saddles of the locking elements are located at an angle, and the locks are a wedge, which is made in such a way as to best meet the technological needs of the pipeline. They can be rigid, elastic or double-disc.
In any case, when adjusting, the wedges fit tightly into the space between the seats and reliably close the path of movement of the pumped product. The type of wedge is selected based on the technical requirements for the medium transportation system used.
Types of valves
- A flanged valve is the most common type of shut-off valve, widely used in pipeline systems with a diameter of up to two thousand millimeters. They are used both in industry and in housing and communal pipelines that provide residents with heat, water, gas and sewage disposal. At the same time, they are able to guarantee high-quality movement of petroleum products, steam, liquid or other media with a pressure of up to 25 MPa and an upper temperature limit of 565 degrees Celsius. The flanged gate valve has a reputation for reliable and efficient control and control.
- The gate valve is not intended to regulate the flow of the transported medium. It can only be in two positions - open or closed - and is installed on horizontal pipelines. Valves are available with rising or non-rising spindles. In addition, experts distinguish them by the method of fastening, using flanged or flangeless connections. Design features include a special control dial that guarantees quick raising or lowering of the working rod. Blocking the flow of movement in the environment is provided by special oil seals and seals.
- Parallel valves have a design similar to wedge valves. The main difference is the presence of parallel disks, which guarantee reliable closing of access to the material pumped through the pipeline. A fairly simple design makes it possible to provide the pipeline with high-quality fittings at a minimal price, while guaranteeing the durability and efficiency of the system as a whole. Since it has minimal hydraulic resistance, it is the main element for adjusting main pipelines for housing and communal services.
- The hose valve ensures the operation of pipelines transporting various media. It makes it possible to quickly and efficiently block the movement of liquid, steam or fuel and is connected to pipes using flange connections. The mechanism is a metal case with pinch devices and special pipes located inside, guaranteeing the reliable operation of the pipeline supplying fuel, steam or water. The temperature of the pumped medium should not exceed 170 degrees Celsius, and the pressure should not exceed 1.6 MPa.
A wedge valve is nothing more than one of the types of shut-off valves. Today, wedge valves are actively used not only when transporting liquids, but also any other media.
Wedge valves have a fairly simple design. This means that it practically does not break down in the long term. Reliability is one of the main qualities of a locking mechanism.
As mentioned above, the said valves are shut-off. This means that by rotating the spindle, the medium supply can be completely shut off. Below are the parts that make up a wedge gate valve:
- body (cast steel);
- spindle;
- wedge.
In this case, the mechanism that locks the line may be partially located outside. Do not also forget that the device itself may also have a flange design.
In this case, the case is replete with holes that are intended for screws. Such valves are much easier to install. You just need to remember that you need to install the bolts with the same tension, progressively tightening them evenly throughout the entire body.
The valve is installed in those sections of the route where there is sufficient space. Naturally, the spindle itself can be rotated, both with the help of muscular force and thanks to the torque generated by the electric motor.
It is worth noting that an ordinary structure, due to an increase in size and weight, can be used even in the oil industry. Gas pumping is impossible without shut-off valves.
In particular, in emergency situations, wedge valves are often the only way to stop the flow of media. In all other cases, the above becomes impossible.
In conclusion, it must be emphasized that the spindle itself is made of a different grade of steel. It is in direct contact with the environment. Therefore it must withstand heavy loads.
We are talking not only about mechanical deformations, but also about temperature. For this reason, only hardened steel is used. It has not only high strength, but also ductility.
Spindle breakage is the worst thing that can happen to shut-off valves.
The video will clearly demonstrate the design of a wedge valve, and also outline the main scope of application of the valve:
Based on materials from: http://www.armprof.ru/catalog/zadvizhki-klinovye/
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Advantages and disadvantages of steel valves
Based on the type of control, these devices are divided into valves with manual control (using a steering wheel), electric, hydraulic or pneumatic drive. Valves of large diameters are usually equipped with gearboxes, which can significantly reduce the effort when moving the valve.
The advantages of valves most often include the following features:
- simplicity of design compared to other types of shut-off valves
- short device length for easy installation
- wide range of external conditions in which the valves are allowed to operate
- low open flow resistance
Among the main disadvantages of valves, the following are most often mentioned:
- long time for full opening or closing
- gradual wear of the seals in the valve body and gate, ultimately leading to the need for repairs, which is difficult to perform without taking the valve out of service
- requirements for free space at the installation site of the valve, which is due to the large operating height (primarily for valves with a rising spindle) to ensure full speed shutter
Valve components
Depending on the principle of operation of the shut-off part, wedge, gate, parallel and hose valves are distinguished. Let's look at what a steel valve consists of using the example of a wedge valve with a spindle. The valve body and cover form a working cavity within which the valve (in this case wedge type) moves. On both sides of the body there are connecting units for installing the valve into the pipeline. These units are most often designed for flange connection, but there are also options for mounting using a coupling or by welding. In the internal cavity of the body there are 2 seats with sealing surfaces (depending on the type of valve, these surfaces can be located at an angle to each other or parallel), to which in the closed position the sealing surfaces of the wedge valve are hermetically adjacent.
and with the help of the spindle and the running nut, which make up a threaded pair, the valve moves perpendicular to the axis of the pipeline along which the working fluid is transported. This method of moving the valve using a threaded pair is used in the case of a manual or electric valve drive. If the valve is equipped with a hydraulic or pneumatic drive, then the rod attached to the valve moves forward under the influence of the drive. In our case, the spindle passes through the sealing gland in the cover and is connected to the steering wheel, which is the valve control.
Valves with rigid wedge
Wedge valves have several varieties, which differ in the shape, type and material of the wedge. Regardless of the wedge type, general device The valve looks like this. The body contains seats that form a small angle with respect to each other. In the closed position, a wedge fits tightly onto these saddles and completely covers the space between them. If a rigid wedge is used in the valve design, then, subject to high precision processing of the sealing surfaces of the wedge and seats, excellent sealing tightness is ensured. However, this type of wedge also has disadvantages associated with possible jamming of the valve in the event of excessive force being applied when closing it, as well as in the event of temperature fluctuations caused by changes in the ambient temperature or the transported liquid or gas. Corrosion or wear of the sealing surfaces also leads to loss of sealing of the connection or difficulty in opening the valve.
Gate valves with double disc wedge
To reduce the risk of jamming, the valve design uses a so-called double-disk wedge, which consists of two rigidly connected disks placed at an angle relative to each other. Thus, the composition of a steel gate valve with a double-disc wedge is increased by several parts. Thanks to the self-alignment of the disks relative to the seats, the requirements for the identical angles of the seats and disks are reduced, and the tightness of the valve in the closed position is increased. The design of a double-disc wedge is more complex than that of a traditional one, but the complexity is compensated by less wear of the sealing surfaces during operation and a reduced force applied to reliably close the valve. Shut-off valves with a double-disc wedge, used on ships, are also called clinket valves.
Gate valves with elastic wedge
An intermediate type, which has the convenience of a double-disk wedge in the field of compensating for deformations of the valve body due to temperature fluctuations, and at the same time representing a simpler design, is an elastic wedge. Unlike a rigid wedge, it does not require such precise adjustment of the valve surfaces and seats. This is due to the design of the elastic wedge, which consists of two disks connected by an elastic bending element, which ensures the necessary tightness of the contact between the sealing surfaces.
Parallel and gate valves
The design of parallel gate valves is characterized by the presence of two parallel disks and two seats parallel to each other. In the closed position, the discs are pressed tightly against the seats using a specially designed lowering wedge-shaped fungus. A type of parallel valve is a gate valve. This valve uses only one disk, which reduces the tightness of the locking and makes it possible to use the valve only in pipelines with one direction of movement of the transported working fluid. Most often, valves of this type are used in pipelines for pumping sewage and other wastewater, pulp or sludge.
Hose type valve
The hose valve is structurally completely different from other types of shut-off valves in the absence of seats and sealing surfaces of the valve.
The answer to the question of what this type of valve consists of is the following. Such a valve contains a pipe or hose made of elastic material installed in the body, through which the working medium is transported through the valve. In the process of closing the valve, this hose is completely compressed due to the action of the rod on it. Hose valves are used in pipelines pumping working media with a high viscosity index. This type of valve is classified as valves because the principle of its operation is also associated with the movement of the spindle or rod in a plane perpendicular to the axis of the pipeline.
Retractable or non-retractable spindle
Based on the location of the running unit, which is a threaded pair of a spindle and a nut included in a pipeline valve, the devices are divided into valves with a retractable and non-retractable spindle. The first type of spindle involves the location of the spindle outside the housing. In the process of opening or closing the valve, the running nut rotates, which leads to translational movement of the spindle, the upper end of which extends by an amount equal to the stroke of the valve. To allow the spindle to move, the spindle nut is located above the top of the cover.
For example, steel gate valves 30s41nzh and 30ls41nzh are of this type with a retractable spindle. The advantage of this design is the absence of contact of this unit with the working environment, which can have an aggressive effect, as well as providing free access to the running unit for carrying out maintenance procedures. The disadvantages of this design include the requirements for free space for moving the spindle, which leads to a greater construction height when installing such a valve.
In valves with a non-rising spindle, the advantages and disadvantages are exactly the opposite of the previous design. In such a valve, the spindle makes only rotational movements, and the running nut, which is connected to the valve, in the process of opening or closing the valve, is screwed onto the spindle and moves the valve. Since in this type of design the running unit is exposed to the transported working medium, valves with non-rising spindles are used in pipelines pumping non-corrosive liquids, oils and petroleum products. Due to the fact that this design of the spindle significantly complicates access to it for maintenance procedures, valves of this type are rarely used in high-security facilities. But the low requirements for additional space for installing the valve allow it to be used in conditions of limited space for installing shut-off valves, such as wells, wells and other underground communications.
Methods for manufacturing valves and materials used in construction
Gate valve bodies are most often made by casting from various grades of steel, cast iron or aluminum alloy. However, some steel cases, as well as cases made of titanium alloys, are manufactured by the so-called stamp-weld method, which involves stamping blanks from rolled sheets at the first stage, and welding the blanks at the second stage (in an inert environment for titanium alloys). The second manufacturing method is in no way inferior to casting; moreover, in terms of its strength characteristics, due to the use of materials of increased strength and wear resistance, such valves are used under conditions of increased requirements for the characteristics of the shut-off valve material. The use in production of modern methods of quality control of joints obtained by welding allows us to guarantee the highest quality of welded seams and ensures the possibility of using such valves at high-risk facilities, including nuclear power plants.
The sealing surfaces of most valves are made of brass or fluoroplastic, a grade of steel that is resistant to corrosion. In some types of wedge valves, the sealing surfaces may be coated with rubber, and in hose-type valves, the pinch hose is made from rubber or similar elastic materials.
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Application area
Valves are used as shut-off and flow-regulating fittings in pipes; sometimes they are used to control the flow volume by reducing the nominal diameter of the passage.
Valves are rarely used in everyday life; they are mainly used to regulate water and gas supply in housing and communal services, in pipelines for transporting gas, oil, food and chemical industries when supplying technological components in the production process.
Shut-off elements are used on pipelines with large nominal bore diameters; the materials used are inexpensive ferrous and non-ferrous metals in various combinations.
Fig.1 Shut-off equipment for water supply
What are valves: purpose and main structural elements
A valve is a type of pipeline fitting designed to block or regulate the flow of a substance passing through a pipeline. They can work in environments with gaseous, granular, and liquid substances of varying viscosity and chemical activity.
The main structural elements in a valve system of any design are:
- Frame. It consists of a main part and a cover, the first is placed directly in the line, and the second is used to fasten and control the movement of the shut-off element. The body is made of metal: steel alloys, stainless steel, brass, aluminum, malleable cast iron, the latter is coated with anti-corrosion mica-containing paints or epoxy primers.
- Constipation. The element (damper) is designed in the form of a metal wedge, gate, disk or flexible pipe made of elastic materials; to increase the tightness, the metal is sometimes coated with rubber (elastomer). When moving, the assembly fits tightly into the profile seat located in the body and seals the channel.
- Drive system. Designed to control the movement of the damper in the assembly, it is represented by mechanical structures in the form of a flywheel moving on a retractable or stationary rod; pneumatic, electric and hydraulic drives are also used.
Rice. 2 Pipeline valves made of steel - parameters according to GOST 9698-86
Advantages of valves
The main parameters of valves are regulated by GOST 9698-86; products used in industry have the following features:
- Simplicity of design. The body consists of a main part placed in the line using a flange or coupling threaded connection (for small diameters), its cover is secured with nuts or bolts - this simplifies the procedure for installing, dismantling and repairing the device.
- High specifications. Sliding valves, depending on the purpose and operating conditions, can withstand operating temperatures from -60 to +565 C., pressure from 0.16 to 25 MPa. (1.6 - 250 bar.) in steel structures. In this case, the pressure limit for cast iron is 25 bar, for products made of non-ferrous metals - 40 bar.
Rice. 3 Shut-off cast iron flange fittings
- Versatility. The devices can operate in pipelines for any purpose with high chemical activity of the transferred substances, and are designed for use in pipelines with diameters from 15 to 2000 mm.
- High hydraulic characteristics. Gate valves are selected according to the internal diameter of the pipelines, which has standard values, so they do not affect the hydraulic resistance in the line. The smooth movement of the damper when blocking the flow of the transported substance avoids water hammer in the system. The design of the sliding elements and the body seat is designed to create high tightness of the closed channel.
- Good maintainability. Installation and repair of fittings and fittings with valves is easy to carry out if you have simple tools and components - adjustable plumbing wrenches, gaskets. In case of wear, valves and gaskets can simply be removed and replaced with new ones.
- Long service life. Body parts and valves are made of strong, durable materials designed for use in a specific working environment; internal valves are made of corrosion-resistant metals - this significantly increases their service life.
Rice. 4 Types of valves made of non-ferrous metals
Minuses
In the manufacture of shut-off valves, cast iron is often used to reduce costs; such designs have the following disadvantages:
- The high weight of the valves makes it difficult to install units with large pipeline diameters—several workers or special lifting equipment may be needed to hold the massive part. For example, the weight of a cast iron constipation with a nominal bore of 1600 mm. According to GOST 9698-86 it is 10025 kg.
- Cast iron is a corrosion-unresistant material; over time, its inner surface rusts, becomes covered with shells and limescale - this leads to a failure of sealing when the flow is blocked.
- Another disadvantage of cast iron is its fragility, which leads to irreversible damage to the product under strong impacts.
- A cheap gland seal with packing, which is used in budget cast iron products, is not sufficiently tight compared to modern mechanical seals - during its operation, leaks of the transported substance often occur.
Rice. 5 Operating principle of a wedge-type valve
Valves for pipelines - types and classification
Gate units have different design and physical parameters; according to the design and classification of gate valves, they are divided into the following classes:
- According to the housing manufacturing technology:
- Welded.
- Casting is the main method of forming hulls.
- Forged or stamped - the technology is used to create high-strength cases; the parts are connected to each other by welding.
- Combined - made from forged and stamped parts by welding.
- By seal type:
- Graphite-reinforced, liquid metal.
- Stuffing box - the movable spindle or rod is separated from the working medium by a stuffing box, impregnated with oil and compressed by a union nut or a special part - an oil seal.
- Bellows - tightness is achieved through the use of corrugated elastic shells made of metal and synthetic materials.
Rice. 6 Disassembling the wedge-shaped system (body, type of valve wedge)
- By type of force transmission to the valve:
- Rotary - used in manual mechanical systems, where the screw spindle moves due to the flywheel.
- Translational - the rod has a cylindrical shape and moves by transmitting force to it hydraulically or electrically.
- By drive type:
- Manual - a flywheel and a threaded spindle are used to transmit force.
- Electric - the valve is controlled by a moving spindle, which is the armature of the electric coil.
- Hydraulic - hydraulic fluid exerts pressure on a movable rod with a valve placed in a sealed cylinder.
- Pneumatic - the spindle moves due to the pressure of compressed air on its surface.
Rice. 7 Drives
- According to the design of the valve assembly:
- Wedges. The shutter is wedge-shaped and, when lowered, is located between two inclined seat surfaces.
- Parallel (single or double disc, gate). The gate element is made in the form of a flat disk or gate, which locks the channel, descending into small profile recesses in the body.
- Hose. When the system operates, the shutter mechanism compresses the elastic rubber hose, thereby blocking the channel of movement of the substance.
- Rotary. A shut-off element in the form of a disk is located in the pipe channel on its center line; during operation, it rotates around the central axis and blocks the flow of the passing substance.
Wedge valves
This type of valve device is a valve with angled surfaces, which, when released, is located in a wedge-shaped seat.
Hard wedge
The model is characterized by its low cost, simplicity, rigidity, reliability and good tightness parameters; during manufacture it requires the use of high-precision equipment. The wedge is hinged to a spindle located in the top cover and lowers into the channel along guides built into the body; the system is capable of working with large pressure drops. Disadvantages include difficult repairs and jamming when exposed to high temperatures as a result of linear expansion of the metal when heated.
Fig. 8 Double-disc wedge - design
Wedge with two discs
Wedge models of this type consist of a damper in the form of two disks placed at an angle with an expanding part between them (looks like a spherical fungus) - this allows it to self-install, while ensuring a high density of channel closure and eliminating jamming.
Types of valves with two disks have a complex design and are therefore expensive; their advantages are low wear of the valve and seat surfaces due to the lack of contact along the path of movement, a high degree of sealing, and a small applied force to close the passage.
The devices are produced only with a retractable stem; many models come with o-ring seals on the shutter disks, which improve the sealing of the passage.
Rice. 9 Types of rotary systems
Elastic wedge
In this design, the valve drive is cut into two parts and a spring element is located between them - this allows the sealing elements to move relative to each other at a small angle, thereby ensuring better contact with the seat ring. During manufacturing, high-precision adjustment is not required, high-temperature jamming is excluded, the disadvantages include increased abrasion of the wedge planes as a result of early contact during lowering.
Rotary
A device of this type is called a butterfly valve; during operation, the disk is located in the flow of matter and moves in its direction. Discs are used in systems with pipeline diameters up to 1200 mm. at ambient temperatures from -200 to +450 C. and pressure up to 600 bar. The device has a simple design, small size and weight, seals the sealed channel well, and is easy to repair. Disadvantages include high flow resistance, operation only in one direction, and the inability to use in environments with high viscosity and contamination.
Parallel (gate)
In these devices, the surfaces of the seats and the shutter disk are parallel; when lowered, the disk (gate) seals the passage due to the pressure of the conductive medium on its surface. The disadvantages include high energy consumption for movement as a result of friction of the sealing rings of the seat and gate along the entire path of movement and, accordingly, increased abrasion of the sealing surfaces. Used with reduced requirements for tightness, easy to maintain and repair.
Fig. 10 Parallel gate valves
Hose
When transporting aggressive chemical media in the system, valves must have high corrosion protection - the best option in this case is to use hose-type devices. The unit has a working channel in the form of an elastic flexible hose, which, when the flow is blocked, is compressed in the middle part.
Rice. 11 Hose type valve - operating principle
Marking
The marking of sliding pipeline fittings is regulated in accordance with GOST 4666-75; it is carried out on the body or on a plate indicating the following data:
- Business name;
- pressure, temperature;
- bore diameter;
- steel grade in the case of using materials with special properties (increased corrosion, temperature resistance);
- quality mark, if available.
Rice. 12 Marking examples
Installation of shut-off valves in water supply systems
The installation of a valve in a main industrial pipeline is carried out by qualified specialists, and the most common method is to connect the elements to each other using flanges. When carrying out work on the water main, observe the following installation features:
- Removal of water supply shut-off valves is carried out only in the absence of working fluid in the system; if necessary, the pipes at the joints are protected from dirt, scale, and limescale.
- Before installing the shut-off valves, check the quality of the flanges - the flange washer should not have cracks, scratches, gouges or other defects.
- The shut-off valves of the water supply system are placed on a strictly straight part of the pipeline and on flat areas of the earth's surface - this avoids excessive stress in places of bends and distortions that cause leaks. When installing heavy units, additional rigid supports are used.
- During operation, it is not allowed to apply excessive force to the flywheels by which the shut-off valves are activated - this can lead to breakage and cracks.
- Installation should be carried out with a soft sling, avoiding fastening to the rod or steering wheel and trying not to damage protective covering- this leads to premature corrosion. Falls from heights and mechanical shocks are unacceptable.
Rice. 13 Methods of installation and configuration of locking devices
Before choosing shut-off valves, it is necessary to take into account its characteristics in accordance with GOST - industrial steel products have the highest parameters. Sliding units for pipelines made of non-ferrous metals are suitable for domestic use - they have small nominal diameter sizes and easy installation using threaded couplings.
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Advantages and disadvantages
A cast iron gate valve is a popular type of shut-off valve, which is used in the energy sector, industry, housing and communal services, and agriculture. The product is a simple, reliable and universal system that lasts a long time. The valve closes or opens the flowing volume with just two positions.
The advantages of locking products include the following points, which characterize them as:
- simple in design;
- compact in volume;
- resistant to corrosion and chemical influences;
- having low hydraulic resistance;
- universal (for different working environments);
- durable when used;
- resistant to various external conditions.
The disadvantages of cast iron structures include:
- probability of damage;
- wear of parts that are difficult to repair;
- the time required to close or open the structure.
The advantages of a cast iron valve are much greater than the disadvantages.
IMPORTANT! To prevent damage to the integrity of cast iron fittings, it is prohibited to deform it.
Design and operating principle
There are many types of cast iron products: hose, gate, parallel, etc. Preference is given to wedge ones, as they are considered the most functional. Such products differ from others in the design of the sealing rings, which are placed at an angle to each other.
The structure of a cast iron product is represented by the following components:
- body (substance passes through it);
- wedge (ensures tightness) is a locking element, which is represented by one or two disks;
- manual or electric flywheel (valve, gearbox, electric drive) – used for control;
- steel retractable spindle (moves the product);
- housing cover (comes with a seal).
The principle of operation is that when the valve is turned, the shut-off element, using a spindle, begins to move upward, perpendicular to the flow. In this way, the tube lumen opens, and the transported substance passes smoothly. To close the passage, on the contrary, turn the valve and the wedge lowers into place.
IMPORTANT! The retractable spindle requires constant care: it must be constantly cleaned and lubricated with special machine oil (for example, VD-40).
Types of valves
There are several types of cast iron products. Based on the design of the gate element (wedge), the following types are distinguished:
- Tough.
Such products provide very good tightness and require precise workmanship. Here it is necessary to completely match the angle of the wedge and the saddles. Disadvantages include the ability to jam and the occurrence of operational difficulties during strong temperature fluctuations.
- Double disc.
The design of the locking element consists of two firmly fastened metal wedges. This type has a reduced likelihood of jamming and is less susceptible to corrosion and negative environmental influences.
- Rubberized.
The disk of the product is covered with a dense rubber layer, which increases the tightness of the cast iron structure. The product provides excellent protection against corrosion and is suitable for transporting highly aggressive substances.
- Elastic.
This design is simple and in many ways similar to a double-disc valve. The only difference is that the working parts are connected to each other by elastic elements, which reduces the tendency of the product to hull deformation and temperature changes that affect the tightness.
- Gate.
The valve is represented by a locking element in the form of a knife. This design allows you to well block the flow of bulk and liquid substances.
According to the generally accepted classification, all cast iron products are divided into wedge and parallel, which are: high, medium and low working pressure. Parallel structures have 2 connected disks, in which a wedge is placed between them and goes down. The ring seals are located perpendicular to the axis of the product.
IMPORTANT! Belonging to one type or another can be recognized by the body of the structure. Cast iron valves with low pressure are presented in a flat shape, with medium pressure – oval, with high pressure – spherical.
Depending on the location of the running gear, cast iron systems can be either with a retractable or non-retractable spindle. The second type can only be used on pipes through which non-aggressive and clean (without impurities) media pass due to their strong susceptibility to corrosion.
In addition, cast iron products are divided into: full bore (the nominal diameter coincides with the diameter of the passing pipe) and tapered (smaller diameter, reduces rubber wear and reduces torque).
IMPORTANT! The device can be controlled manually, electrically, or using a hydraulic or pneumatic drive. Installed gearboxes make process control as easy as possible.
Features of the cast iron system
Valves are produced with different diametrical sizes: from 50 to 420 mm (80, 100, 125, 200, 350), designed for pressures of 10 bar and temperatures up to 200˚C. Systems with a large diameter are most often equipped with an electric drive, which allows you to control the system remotely and install it in hard-to-reach areas of the pipe line. If the electric drive comes complete with return springs, this increases the operating speed of the valve per control signal.
Frequently used wedge valves have the following features:
- the passage is closed with a wedge mounted on the spindle;
- capable of withstanding gas movement up to 30 m/s, liquid movement up to 4 m/s;
- requires frequent use;
- sealing rings wear out faster than in parallel (exception: rubber-coated products that require the least effort during operation);
- ease of use - due to the reduction in torque time and smooth operation of rubberized systems;
- compliance with technical requirements of international standards;
- strength and tightness.
Depending on the type of connection, there is a flanged valve. This product has characteristic features (use life up to 8 years) and is used for:
- operating pressure up to 1.6 MPa;
- temperature conditions – up to 75˚С;
- diametric pipe size - 50-3000 mm.
Features of the operation of valves include the ability to select valve control: manual or electric (drive). For small diameters (up to 150 mm), manual control is installed, and in all other cases, electric control. The second method is convenient for remote control of the product.
IMPORTANT! The highest tightness is provided by cast iron products with a rubberized wedge.
Installation of cast iron products
Mounting of the structure to the pipe is carried out using fastenings from a flange, socket and couplings, or by welding. Since the valve design is simple, its repair and maintenance are quick, which ensures a long service life.
The most popular is the flange mount. Its installation is carried out in the following way:
- First, check compliance with the cut flanges.
- Then ring seals are installed in the channels on the plates.
- Then the flanges are attached to each other using bolts and tightened with nuts.
- The tightness of the joints must be checked. If necessary, the connection is sealed with a special sealant.
Cast iron fittings are used for steam systems, sewerage, and transport of bulk solids.
IMPORTANT! You can install a cast iron valve yourself. Installation must be carried out in such conditions that foreign substances and dirt do not get into it.
Application of gate valves in housing and communal services
For the installation of pipes in the national economy (any area of industry), the valve is a necessary device and reliable shutoff of the transport of substances. Cast iron products are successfully used in many areas of housing and communal services for the passage of steam, mixtures, mixed materials, and liquid substances through pipes.
Popularity is due to:
- simplicity of the device;
- use in all climatic zones;
- ability to repair;
- low cost;
- strength (cast valve body).
A reliable and durable shut-off device can ensure safe and permanent operation of the pipeline for such utility networks, as heating; sewer; gas; cold and hot water supply; pumping oil.
You can purchase a locking structure at any specialized supermarket.
To move various media (liquid, bulk, gaseous) through a pipe system, a special valve is often used - a wedge-shaped valve, which is characterized by high efficiency and functionality.
Wedge design
The product with a wedge is used for heating systems and related communications, pumping hydrocarbons in liquid form, gaseous substances and chemical reagents, hot and cold water. The use of the design in the oil, gas transportation, energy industries, as well as in the housing and communal services sector speaks for itself.
The valve has technical features and also helps to close or open movement along the pipe (hence the 2 phases of operation - open/closed). This is manifested in the fact that the seat of the locking movable element is placed at an angle, and the lock itself is made in the form of a wedge. During operation, the wedge fits into the gap between the seats and reliably blocks the path of the substance moving through the pipe.
Depending on the valve, the following wedge-shaped valves are distinguished:
- hard;
- double-disc;
- elastic.
The rigid wedge has good tightness and stability due to secondary elastic seals. Double-disc products wear out less than rigid ones (in which the seals quickly fail), have a high reinforcing ability and a low probability of jamming. But their dimensions are much larger than rigid ones, which leads to additional metal consumption.
An elastic valve is represented by disks connected to each other by elastic parts. This product is resistant to temperatures and operating pressure, but does not cope well with media that contain impurities.
Rigid products are less metal-intensive, but are labor-intensive to manufacture. Double-disc ones are always large in size, but easy to make. Elastic - are average in terms of performance between rigid and double-disc.
IMPORTANT! The design of the regulating element of the valve with a wedge can be different models, but all of them are made according to the quality standards of the current GOST 24856-2014.
Device and principle of operation
A valve with a wedge quickly blocks the flow of a moving substance. For this, manual flywheels and automated systems are used, which is very convenient for remote objects.
The device of the product is very simple and is presented:
- metal body with locking elements;
- spindle nut inside or outside the housing (extends the spindle to its full extent);
- rod (activates the shutter);
- flange connectors (ensure tightness);
- sealants (rubber, polyurethane, fluoroplastic, metal surfacing, elastomers).
Depending on the spindle, wedge structures can be retractable or non-retractable (compact). The second type is often used for underground pipelines.
Retractable spindles - cast iron or steel, have the property of full bore (with a non-narrowed recess for the diameter of the nozzles). The presented products are gate valves and are equipped with an electric wire.
Non-retractable spindles are always immersed in the transported medium and therefore require frequent replacement. Of course, such a device wins over retractable devices due to compactness and building mass, but they are durable and wear-resistant.
IMPORTANT! The product is driven by a flywheel or electric, pneumatic, hydraulic drives. Manual or automatic control of the wedge valve is selected depending on the pumped medium.
Advantages and disadvantages
Like any device, the wedge design has different sizes, can even be installed on polymer pipes, and has its pros and cons. The advantages include:
- simple internal structure and maintenance;
- small dimensions in length;
- functional ability under different level conditions;
- lowest hydraulic resistance in open passages;
- versatility (use at different temperature fluctuations and pressure);
- ensuring the movement of substances in different directions using a gearbox;
- durability;
- smoothness when closing;
- wide size range;
- low repair costs.
The disadvantages of the products include:
- large working height;
- rapid wear of the seal;
- time spent on unscrewing or screwing the valve;
- small permissible difference in the gate;
- compliance with operating rules.
Features of wedge products depend on:
- selected model and flange dimensions;
- bandwidth;
- ability to drive (manual or electric);
- the required level of tightness and ability to withstand mechanical stress;
- planned operating conditions (modes: pressure, temperature, corrosion resistance).
In order for a wedge gate valve to serve reliably, you need to select a suitable model in full accordance with the required operating characteristics.
IMPORTANT! The choice of wedge design depends on the chemical and temperature environment used, pressure, and connecting flange system.
Characteristics of wedge gate valves
Products with a rigid wedge are very tight. But the disadvantage of such a device is the increased risk of the shutter jamming and difficulty in opening during temperature fluctuations of the moving substance or when the seal is erased.
The double-disk design jams less often. Despite the fact that its design is more complex and metal-intensive, it has a low probability of seal abrasion, a high degree of seal tightness, and little effort when closing the product. The body is made of materials such as cast iron, steel, and non-ferrous metals. Devices made of cast iron have the best characteristics, the possibility of many years of operation. They can be coated with polymer coatings to protect them from aggressive external environments.
Steel products are used at high temperatures and pressure parameters in pipes. Such valves are cast, stamped and welded. Brass, copper, titanium, mixed or bronze valves are used at temperatures up to 150-200*C. Knife-shaped structures connected using flanges are simple to construct. They are made of cast iron and also steel, which are driven by a flywheel.
There are also rubberized products. Such wedge representatives are made of cast iron and steel, but are covered with polymer rubber on top. Structural seals can also be made using hard surfacing, laser hardening, plasma spraying, or fluoroplastic. There are also sealing elements: without rings; ring (made of brass or fluoroplastic); with anti-corrosion surfacing; rubber.
IMPORTANT! In areas with very low temperature conditions, steel valves are used for pipes. The design lasts a long time and rarely breaks.
Types of valves
Wedge valves are available: full bore and narrowed; with manual control and automatic; with retractable or non-retractable spindle; hard, double-disc, elastic, rubberized; cast iron, brass or steel. In addition to the listed types, there are also flange and gate types. Welded and sleeve valves are rarely found.
The flange device is used in pipes with a diameter of up to 2,000 mm. It regulates and controls the mass moving through the pipes well. The design is used in the housing and communal services sector - for all types of pipes (water, gas, wastewater), and is considered high quality. The maximum pressure in the pipe for such a valve should be up to 25 MPa, and the temperature should be 565*C.
The sliding or non-rising spindle gate valve operates quickly, but cannot regulate the transported substances, and is always in the open or closed position. This product is only suitable for straight pipes. The device is connected with or without a flange.
Gate valve installation
There are several ways to connect a valve to a pipe system. The wedge flange is secured with bolts, the cast iron - with flanges. Steel and coupling products are welded, valves made of non-ferrous alloys are connected with threaded connections, flanges and welding.
The mounting steps are as follows:
- The flange area is cleaned of dirt and lubricants.
- Install the product between the pipe flanges, separating them with spacers.
- Then insert the bolts into the holes made and tighten them, achieving a parallel flange connection.
- Carry out reliable fixation of fasteners.
- The movement of the wedge and the flywheel is adjusted.
Installation of the structure is carried out with the pipe positioned only in a horizontal position. Select suitable gaskets for reliable sealing, which must match in size with the connecting flanges, as well as diametrical bolts.
Wedge valves are represented by a huge assortment; they are produced by many Russian and foreign companies. There are many model designs on the market and in specialized supermarkets that are purchased depending on their purpose.
It is better to entrust the choice of product to a specialist so as not to make mistakes with the parameters. The trouble-free operation of pipe systems with moving substances depends on a correctly selected product.
Wedge devices are of great importance for all spheres of human life. Housing and communal services (heating, gas, water, wastewater), gas, oil, construction mixtures production - all this helps to regulate the wedge valve.
The valve belongs to the category of shut-off valves. To function properly, a pipeline system requires valves. The most common today are wedge type valves.
Advantages of wedge valves
- Simplicity of the device;
- Short working length;
- Products are able to function in conditions with varying degrees of complexity;
- Insignificant hydraulic resistance.
Disadvantages of wedge valves
- Models equipped with retractable spindles have a significant working height;
- To unscrew or screw the valve, you will have to spend a significant amount of time;
- Poor wear resistance of the seal.
When choosing the AVK gate valve model, we take into account chemical environment, temperature and pressure in the pipe, as well as the connection system carried out using a flange.
Characteristics of wedge gate valves
In the body of such a valve there are special seats placed at a slight angle relative to each other. The product's shutter has a wedge-shaped configuration. It can be rigid, elastic or with two discs. If the valve is closed, the wedge will fit very tightly between the seats.
A model with a rigid wedge will make the locking device super tight. The disadvantage of this valve design is the high risk of the valve jamming. In addition, such a model is very difficult to open. This is especially noticeable if there are significant temperature differences in the working environment and if there is significant abrasion of the seal.
A valve with two discs jams much less often. Its design is quite complex, but has many advantages. Its seal wears very little during operation, and the locking device has high level tightness. Closing the product does not require significant force.
Steel and cast iron gate valves
Some models of wedge gate valves are equipped with rising spindles. Such spindles are made of cast iron and steel. They are not able to regulate the flow of the medium. Such models can play the role of shut-off valves. In this case, the locking device of the product must be either closed or open during operation. Products made of cast iron or steel are distinguished by a full bore device. This means that their diametrical recesses, located in special pipes, are not narrowed. This category of valves includes gate valves equipped with an electric wire, as well as models made of cast iron and steel.
Knife valves are connected using flanges. Both cast iron and steel valves are distinguished by their simplicity of design and low hydraulic resistance.
Such products are used in main pipelines, where the working medium moves at significant speed and in a constant mode. The cast iron and steel structures are operated by a hand wheel. In some models, the steering wheel is replaced with an electric drive or with pneumatics and hydraulics
Wedge flanged valves
This valve is used in pipelines designed to move aggressive chemical liquids used in the hydrolysis industry. The model belongs to the category of flanged products, since it has special connecting flanges. Their bolt is made in the form of a strong and reliable wedge.
The valve is mounted on a pipeline located in a horizontal plane. In this case, its flywheel should be directed upward or placed on the edge. If the product is installed on a vertical pipeline, then its flywheel should lie flat