What is a toggle valve assembly. Tutorial on the topic "wedge gate valve". Parallel gate valves: design
In general, the design of the gate valve (Fig. 13) consists of a body and a cover, forming a cavity in which the working medium is located under pressure and inside which the gate is placed (in the drawing it is a wedge). The body has two ends for connecting the valve to the pipeline (connecting ends are flanged and welded).
As a rule, two seats are located inside the body, parallel or at an angle to each other (see Fig. 13), sealing surfaces of the valve are pressed against their sealing surfaces in the “closed” position. The shutter moves in a plane perpendicular to the axis of the passage of the medium through the body, using a spindle or rod. A spindle with a running nut forms a threaded pair, which, when one of these elements is rotated, ensures the movement of the shutter in the desired direction. This solution is the most common, and is used for manual or electric control. The spindle has one end inside the body connected to the valve, and the other end passes through the cover and the stuffing box (which is mainly used as a sealing device in valves) to connect to the valve control element (in this case, the handwheel
Figure 13 - Wedge gate valve:
1 - wedge; 2 - saddle; 3 - spindle; 4 - body; 5 - cover; 6 - stuffing box; 7 - flywheel
Wedge gate valves
Wedge gate valves (Fig.14) have a gate in the form of a flat wedge. In wedge gate valves, the seats and their sealing surfaces are parallel to the sealing surfaces of the gate and are located at some angle to the direction of movement of the gate. The advantages of such valves are increased tightness of the passage in the closed position, as well as a relatively small amount of force required to ensure sealing.
Figure 14 - Wedge valve device
The disadvantages of valves of this type include the need to use guides to move the valve, as well as technological difficulties in obtaining tightness in the valve.
All wedge gate valves according to the design of the gate can be with a solid, elastic or composite wedge.
Solid wedge gate valves have been widely used because their design is simple and, therefore, has a low cost to manufacture. The one-piece wedge is a very rigid structure, is quite reliable under operating conditions and can be used to shut off flows with fairly large pressure drops across the gate.
The gate valve (Figure 15) consists of a cast body into which the sealing seats are screwed. As a rule, they are made of alloyed, wear-resistant steels. Together with the body, guides are cast and then machined to fix the direction of wedge movement. The wedge has two annular sealing surfaces and is hinged to the spindle through a spherical support. The top cover is connected to the body by means of bolts or studs. To center the cover with respect to the body, it has an annular protrusion that enters the groove of the body. The seal between the cover and the body is provided by a gasket, which is inserted into the groove of the body. A guide sleeve is pressed into the upper part of the cover to prevent distortion of the spindle.
There is also a gate valve design with a solid wedge, but with a non-rising stem, where the stem nut is fixed at the top of the gate. A spindle is screwed into the nut, rigidly connected to the flywheel. The screw-nut system is used to convert the rotational movement of the handwheel (when opening or closing the valve) into the translational movement of the gate.
Figure 15 - Full bore gate valve with solid wedge
1 - body; 2 - saddle; 3 - wedge movement guide; 4 - wedge; 5 - spindle;
6 - top cover; 7 - hairpin; 8 - sealing gasket; 9 - guide sleeve, 10 - stuffing box; 11 - pressure flange; 12 - yoke; 13 - running nut; 14 - flywheel.
Resilient wedge gate valves (Fig. 16). In them, the valve is a cut wedge, both parts of which are interconnected by an elastic (spring) element (elastic rib), which allows the sealing surfaces of the wedge to rotate relative to each other at a certain angle, which ensures their better fit to the sealing surfaces of the seats. This feature of the elastic wedge eliminates the need for individual technological adjustment of the seal and reduces the risk of jamming. Gate valves of this type are manufactured with both rising and non-rising stems (Fig. 17).
The design of the valve gate of this type provides a better sealing of the passage in the closed position without individual technological adjustment. Under the action of the pressing force, which is transmitted through the spindle, in the closed position, the elastic element can bend within the elastic deformations, ensuring a snug fit of both sealing surfaces of the wedge and seats.
Valves of this type have increased reliability at high temperatures (due to the reduction of the risk of uneven thermal expansion, leading to jamming of the valve). However, the risk of jamming in the closed position has not been completely eliminated. A major disadvantage of this type of gate valves is the increased wear of the sealing surfaces of the wedge and seats, since they come into mutual contact much earlier than in gate valves with a solid wedge.
Figure 16 - Resilient wedge gate valve with rising stem
1 - saddle; 2 - shutter; 3 - body; 4 - running nut; 5 - sealing gasket;
6 - spindle; 7 - top cover; 8 - ring gasket; 9 - stuffing box;
10 - pressure sleeve; 11 - flywheel.
Figure 17 - Rising and non-rising stem valves.
Composite wedge gate valves are used when a high degree of tightness of the passage is required with the gate closed.
Gate valve with a composite wedge consists of two discs, between which there is an expanding element made in the form of a fungus with a spherical surface. The fungus rests against a thrust bearing fixed on another disk. To avoid disintegration, the discs are placed in a holder when opening the passage. The force from pressing the spindle is transmitted using an internal disk.
Often there are designs without a thrust bearing. In this case, the fungus with its spherical end rests against the inner surface of one of the disks. The force from the drive is transmitted through the cage to the inner disk. When the spindle moves from the open position to the closed position, the disks do not unclench and there is no friction between the saddles and the shutter. At the moment of touching the lower edges of the disks with the seats, the drive force is transferred to the expansion element and the passage is sealed. Commercially available split wedge gate valves have a rising stem only.
Despite the complexity of the design and, consequently, the high cost, as well as the non-rigid valve, these valves have clear advantages over other types of valves: slight wear of the sealing surfaces of the valve and seats; high sealing of the passage in the closed position; less actuating force required to close the valve.
The absence of friction of the sealing surfaces along the entire path of the valve movement allows sealing the passage in double-disk valves with the help of elastic rings mounted on the valve disks.
Gate valves
In valves of this type, the sealing surfaces of the seats are parallel to each other and are located perpendicular to the direction of the flow of the working medium. The valve in these valves is usually referred to as a "disk", "gate" or "knife".
The advantages of this design are: ease of manufacture of the shutter; ease of assembly, disassembly and repair; no jamming of the shutter in the fully closed position.
Knife gate valves are divided into single-disc
(Fig. 18) and two-disk.
Figure 18 - Single disc gate valve.
1 - gate; 2 - branch pipe; 3 - body; 4 - spindle and gate fastening unit;
5 - saddle; 6 - hairpin; 7 - sealing ring; 8 - gasket; 9 - top cover;
10 - gland packing; 11 - pressure bar; 12 - spindle; 13 - casing;
14 – drive output element; 15 - stand.
In single-disk gate valves, the gate (gate) is made in the form of a shield with a ring having an opening in the lower part equal to the diameter of the passage, which, when the gate valve is closed, shifts down. The passage is blocked by the blind part of the gate. The tightness of the passage is ensured by pressing the valve by the pressure of the medium against the sealing surfaces of the seat from the low pressure side.
The main disadvantages of sliding gate valves are: high energy consumption for opening and closing, caused by the fact that the drive overcomes friction between the sealing surfaces of the seats and the gate along the entire path of movement; significant wear of the sealing surfaces.
Despite these shortcomings, gate valves are quite easy to maintain and repair. The amount of wear is very easily compensated for during repairs by shifting (turning out) the seats. Gate valves are mainly used when high tightness of the passage is not required.
Gate valves type UK 19001 according to TU 647 RK-05772090-032-97 are intended for installation as locking devices on the linear part of the main oil pipelines and on the process pipelines of the PS.
The design of the gate valve provides for a constant calculated pressing of the seat to the gate using special springs, which does not depend on the pressure drop across the gate. The gate is made of carbon steel with a coating that provides reliability when working in oil. The design of the valves provides the possibility of injecting a sealing lubricant into the stuffing box assembly and replacing the spindle stuffing box without reducing the working pressure in the pipeline (Fig. 19). The valve body is unloaded from excess pressure created by the thermal expansion of the transported medium.
Figure 19 - Knife valve design
Of great importance for the operation and scope of valves is the location of the running unit - the spindle-nut. It can be located inside the valve in the working environment or outside the body cavity.
Placement of the "screw - nut" system in the valve, in the ideal case, should ensure both its compactness and easy access to the threaded pair for lubrication and routine repairs without disassembly.
From the point of view of compactness, it is preferable to place the running nut directly on the valve. In this case, the spindle performs only rotational movement and therefore the valve has a minimum height, determined only by the stroke of the valve and the length of the stuffing box. This design of gate valves is called "non-rising stem gate valves".
In this case, the lead thread is located inside the cavity of the valve and when opening the spindle does not move out of the cover, maintaining its original position in height. The running nut in these gate valves is connected to the gate and, when the spindle is rotated to open the passage, it seems to be screwed onto it, dragging the gate along with it.
In gate valves with a non-rising stem, the running unit is immersed in the working environment and therefore exposed to corrosion and abrasive particles in the working environment, access to it is closed and there is no possibility of maintenance during operation, which leads to a decrease in the reliability of the running and stuffing box units.
Taking into account the shortcomings of gate valves with a non-rising spindle, designs have been used in which the stem nut is fixed in the flywheel or directly in the drive, i.e. outside the working cavity of the body. In these designs, the spindle performs only translational movement and moves along with the shutter, as if moving out of the valve. The translational movement of the spindle ensures the best performance of the stuffing box seal. The design allows you to replace a worn running nut without dismantling the valve, and sometimes without stopping the process. However, rising spindle designs have the following limitations:
· increasing the height of the valve (due to the output of the spindle);
The need to protect the threaded part of the spindle from contamination, corrosion and mechanical damage.
In this design, the spindle thread and lead nut are located on the outside of the valve body. The lower end of the spindle is connected to the gate, and when the spindle nut is rotated to open the gate, it performs together with the gate only forward movement, while the upper end of the spindle extends by the amount of the shutter stroke. To allow the spindle to move, the running nut is raised above the top of the cover (i.e. above the stuffing box) approximately the size of the shutter stroke in the design, which is called the yoke assembly.
Virtues of such a design are the absence of harmful effects of the working environment on the running unit and free access for its maintenance, and consequently less wear of the stuffing box and higher reliability of the threaded pair and stuffing box.
To shut-off valves(Fig. 20) include shutoff valves with translational movement of the shutter in the direction parallel to the flow of the transported medium. The shutter (spool) is moved using the screw-nut system. The shut-off valve is used to shut off the flows of transported media in pipelines with DN up to 300 mm at operating pressures up to 2500 kgf / cm 2 and media temperatures from - 200 to + 450 0 С.
Figure 20 - Stop valve
As a rule, the stop valve spindle performs both rotational and translational movement, since its running nut is rigidly fixed in the upper part of the yoke column, which impairs the performance of the stuffing box seal. The spool in shape is a body of rotation with a flat base, on which a sealing ring made of metal is fixed. rubber or PTFE. The spool is pivotally connected to the spindle and detaches from the seat without slipping, which prevents damage to the sealing surfaces.
Compared to other types of shut-off valves, shut-off valves have the following advantages:
Valve advantages:
Possibility of operation at high pressure drops across the spool and at high operating pressures
Simplicity of design, maintenance and repair in operating conditions
Smaller spool travel (compared to valves) required to completely shut off the passage
Relatively small size and weight
application at high and ultra-low temperatures of the working environment
tightness of passage overlap
use as a regulatory body
installation on the pipeline in any position
elimination of the possibility of hydraulic shock
Valve Disadvantages:
· high hydraulic resistance in comparison with other locking devices;
· impossibility of application on streams of heavily polluted media, as well as on media with high viscosity;
large construction length;
· supply of the medium in only one direction, determined by the design of the shut-off valve.
Bugel"handle, arc") - a detail of a mechanism, device, vehicle:Notes
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See what "Bugel" is in other dictionaries:
YOKE- (Hoop) a ring or hoop made of strip iron, put on (stuffed) on an object, for example. on the mast, yard for its strengthening or connection of its components. B. are deaf and hinged. Samoilov K.I. Marine Dictionary. M. L .: State Naval ... ... Marine Dictionary
yoke- ring, hoop, current collector Dictionary of Russian synonyms. bow n., number of synonyms: 3 ring (40) hoop ... Synonym dictionary
YOKE- (from the Dutch beugel) 1) a metal ring at the top of the pile, protecting it from destruction when driven in2)] Pantograph element (tram, trolleybus) sliding along the contact wire3) Metal ring on the mast of the ship for fastening ... ... Big Encyclopedic Dictionary
YOKE- husband, marine iron hoop, forging, lace, clip, coverage. Dahl's Explanatory Dictionary. IN AND. Dal. 1863 1866 ... Dahl's Explanatory Dictionary
YOKE- see Pantograph. Technical railway dictionary. M.: State transport railway publishing house. N. N. Vasiliev, O. N. Isaakyan, N. O. Roginsky, Ya. B. Smolyansky, V. A. Sokovich, T. S. Khachaturov. 1941 ... Technical railway dictionary
yoke- boucle f. German Ear. Text. sl… Historical Dictionary of Gallicisms of the Russian Language
yoke- current collector - [Ya.N. Luginsky, M.S. Fezi Zhilinskaya, Yu.S. Kabirov. English Russian Dictionary of Electrical Engineering and Power Engineering, Moscow, 1999] Topics in electrical engineering, basic concepts Synonyms pantograph EN bow collector ... Technical Translator's Handbook
yoke- (German bugel syfa) 1) a steel ring mounted on the end of the pile to protect it from damage when driving; 2) sea. a metal ring on the ship's mast for attaching gear; 3) email current collector insert of an electric locomotive, tram, ... ... Dictionary of foreign words of the Russian language
yoke- I; pl. yokes, to her and (colloquial) yokes, to her; m. [Dutch] beugel] Tech. 1. A metal ring at the end of the pile (to protect it from damage when driving) or the mast (for attaching gear). 2. Part of the current collector on the roof of a tram, trolley bus, ... ... encyclopedic Dictionary
Yoke- 1. A ring made of strip iron, which protects the upper end of the pile when driving. 2. An iron closed strip covering a number of driven piles (for example, one yoke for fifty piles). (Terms of the Russian architectural heritage. Pluzhnikov ... ... Architectural Dictionary
Books
- Yoke SKY Expert. Italy No. 4, 2012, . The Alps cover the entire upper part of the Italian "boot" - almost all of its ski resorts are located in the north of the country. There are about a hundred of them - towns and villages quite different in character, ...
Gate valves are valve structures with a gate in the form of a sheet, disk or wedge, moving along the sealing rings of the body seat perpendicular to the axis of the medium flow. Gate valves can be full bore and narrowed in the latter, the diameter of the opening of the sealing rings is less than the diameter of the pipeline.
According to the shape of the gate valves are divided into wedge and parallel. The wedge gate valve has a wedge gate valve in which the sealing surfaces are located at an angle to each other. The wedge can be one-piece rigid, one-piece elastic or composite disk. A parallel gate valve has a gate whose sealing surfaces are parallel to each other. Parallel valve can be sliding (single-disk) or double-disk (Fig. 11).
By the nature of the movement of the spindle, valves with a rising spindle are distinguished, where, when opening and closing the valve, the spindle performs a translational or rotational translational (screw) movement.
Valves with a non-rising stem, where the stem only rotates when opening (see fig. 12).
According to the material, they are divided into cast iron, carbon steel, steel, alloy steel, stainless steel. According to the method of manufacturing body parts - cast, forged, welded, forged-welded, stamp-welded and cast-welded. Hydraulic resistance coefficient of gate valves =0.5÷1.5 ( - zeta).
gate valves- fittings of two-position action. They can only be used to turn pipelines on or off. The use of gate valves as control devices is prohibited.
Gate valves are controlled manually (using a handwheel) or remotely (electrically). Gate valves are supplied both with built-in: located on the valve itself, and with a remotely located (column electric drive). In the latter case, the drive with the valve is connected by means of a rod with a hinge.
Gate valves are installed on both horizontal and vertical pipelines. It is advisable to install gate valves with an integrated electric drive on horizontal sections of pipelines with the spindle up. In places where valves are installed, free access must be provided for their maintenance and repair without cutting out from the pipeline, for installation and dismantling.
Gate valves are available with wedge and parallel type gates. Gate valves are mainly equipped with wedge-type gates. A feature of this type of valves is the dependence of the force of pressing the working surfaces of the gate to the working surfaces of the seats on the force on the drive.
The connection of the body with the cover in gate valves has several designs: flanged and flangeless. Sealing of flanged joints is carried out using gaskets, flangeless - asbestos-graphite
» » Design of non-rotating stem nut assemblies for gate valves
When designing non-rotating stem nut assemblies, the thread direction is chosen so that the valve closes when the handwheel is rotated clockwise. This rule is provided by the requirements of Gosgortekhnadzor. Various designs of non-rotating lead nut assemblies are shown in table 1.
Table 1.
| Design | Sketch | Application area |
|---|---|---|
| The nut is screwed into the cover and locked. Large spindle travel. | Gate valves of small sizes. The environment is not corrosive | |
| The running nut is located in the seat of the wedge |  | Wedge gate valves with rotating stem. The environment is not corrosive |
| The running nut is located in the socket of the wedge. Composite nut, brass insert screwed into the cage |  | Wedge gate valves with large passage diameters. Medium is not corrosive. |
| The running nut is located in the sockets of the disks | Double disc parallel gate valves. Environment non-corrosive |
The most common is the design in which the nut is a hollow cylinder with internal trapezoidal and external metric threads. With the help of an external thread, the nut is screwed into the jumper of the yoke and is locked with a screw screwed into the “half-body” simultaneously into the nut and into the yoke. In wedge gate valves with a non-corrosive medium, the stem nut is installed in the seat of the wedge. In wedge gate valves with large passage diameters, in order to save non-ferrous metal, a brass nut is screwed into a holder made of ferrous metal. Nuts located inside the valve cavity are in an environment that is heavy duty and leads to relatively rapid wear and failure. Replacing them is difficult, so their use is limited.