What Is a Stop Valve?
The shut-off valve, also called a shut-off valve, is a forced-sealed valve. When the valve is closed, pressure must be applied to the disc to force the sealing surface to not leak. When the medium enters the valve from below the valve disc, the resistance to be overcome by the operating force is the friction between the valve stem and the packing and the thrust generated by the pressure of the medium. The force to close the valve is greater than the force to open the valve. The diameter must be large, otherwise the valve top bending failure will occur. There are three types of connection: flange connection, screw connection and welding connection. After the self-sealing valve appeared, the medium flow direction of the shut-off valve changed from the upper part of the disc into the valve cavity. At this time, under the action of the medium pressure, the force to close the valve is small, and the force to open the valve is large, and the diameter of the valve stem can be corresponding To reduce. At the same time, this type of valve is also tight under the action of the medium. China's valve "three chemical supply" has stipulated that the flow direction of the shut-off valve will be used from top to bottom. When the shut-off valve is opened, the opening height of the valve flap is 25% to 30% of the nominal diameter. The flow has reached the maximum, indicating that the valve has reached the fully open position. Therefore, the fully open position of the shut-off valve should be determined by the stroke of the disc.
The shut-off valve, also called a shut-off valve, is a forced-sealed valve. When the valve is closed, pressure must be applied to the disc to force the sealing surface to not leak. When the medium enters the valve from below the valve disc, the resistance to be overcome by the operating force is the friction between the valve stem and the packing and the thrust generated by the pressure of the medium. The force to close the valve is greater than the force to open the valve. The diameter must be large, otherwise the valve top bending failure will occur. There are three types of connection: flange connection, screw connection and welding connection. After the self-sealing valve appeared, the medium flow direction of the shut-off valve changed from the upper part of the disc into the valve cavity. At this time, under the action of the medium pressure, the force to close the valve is small, and the force to open the valve is large, and the diameter of the valve stem can be corresponding To reduce. At the same time, this type of valve is also tight under the action of the medium. China's valve "three chemical supply" has stipulated that the flow direction of the shut-off valve will be used from top to bottom. When the shut-off valve is opened, the opening height of the valve flap is 25% to 30% of the nominal diameter. The flow has reached the maximum, indicating that the valve has reached the fully open position. Therefore, the fully open position of the shut-off valve should be determined by the stroke of the disc.
The opening and closing parts of the stop valve (Globe Valve) are plug-shaped discs. The sealing surface is flat or conical, and the discs move linearly along the center line of the valve seat. The movement form of the valve stem (general name: dark rod), also has the lifting and rotating rod type which can be used to control various types of fluids such as air, water, steam, various corrosive media, mud, oil, liquid metal and radioactive media. flow. Therefore, this type of shut-off valve is very suitable for shut-off or regulating and throttling. Because this type of valve has a relatively short opening or closing stroke and a very reliable shut-off function, and because the change in valve seat opening is proportional to the stroke of the valve disc, it is very suitable for regulating flow.
- Chinese name
- Shut-off valve
- Foreign name
- stop valve
- Function
- Cut-off, regulation and throttling
- Classification
- Channel direction class
- Alias
- Shut-off valve
- Link
- Flange connection, screw connection, welding connection
Globe valve works
Globe valve, also called shut-off valve, is used Illustration of thread stop valve
One of the most widely used valves is popular because of the low friction between the sealing surfaces during opening and closing, relatively durable, low opening height, easy manufacturing, and convenient maintenance. And suitable for high pressure. The closing principle of the shut-off valve is to rely on the pressure of the valve rod to make the sealing surface of the valve disc and the sealing surface of the valve seat closely to prevent the medium from flowing. China's valve "three chemical supply" has stipulated that the flow direction of the shut-off valve is always from top to bottom, so there is directionality during installation. The structural length of the globe valve is longer than that of the gate valve. At the same time, the fluid resistance is large. During long-term operation, the sealing reliability is not strong.
As one of the most important shut-off valves, globe valves play an important role in the aerospace field. As an important component of aerospace equipment, the shut-off valve realizes the functions of media transportation, cut-off, adjustment, etc. Its sealing performance directly affects the safe and reliable operation of aerospace equipment. Studying the influencing factors and influencing laws of typical globe valve sealing characteristics has guiding significance for the structural design of the valve sealing pair, thereby improving the sealing performance and reliability of the valve. [1]
Globe valve globe valve working principle and characteristics
The valve plays an important role in cutting off and throttling the medium in the pipeline where it is located. As a very important shut-off valve, the valve is sealed by applying torque to the valve stem. The valve disc exerts pressure to make the valve disc sealing surface and the valve seat sealing surface closely fit to prevent the medium from leaking along the gap between the sealing surfaces.
The sealing pair of the cut-off valve is composed of a valve disc sealing surface and a valve seat sealing surface, and the valve rod drives the valve disc to move vertically along the center line of the valve seat. During the opening and closing process of the shut-off valve, the opening height is small, the flow rate is easy to adjust, and the manufacturing and maintenance are convenient, and the pressure is applicable in a wide range.
Compared with the other commonly used shut-off valves in industrial production, one by one, in terms of structure, the cut-off valve is simpler than the former, which is easier to manufacture and maintain. In terms of service life, the sealing surface of the shut-off valve is not easy to wear and abrasion, and there is no relative sliding between the valve disc and the seat sealing surface during the valve opening and closing process. The service life of the pair of shut-off valves has a small valve flap stroke during the fully-closed process, and its height is smaller than that of the valve. The disadvantage of the globe valve is that the opening and closing torque is large and it is difficult to achieve rapid opening and closing. Because the flow passage in the valve is relatively tortuous, the fluid flow resistance is large, resulting in a large loss of fluid power in the pipeline. [1]
Globe valve classification
Globe valve according to channel direction
1) Globe valve
2) DC-type globe valve: In a DC-type or Y-type globe valve, the flow path of the valve body and the main flow line are inclined, so that the damage in the flow state is less than that of a conventional globe valve, so the pressure loss through the valve is corresponding It's small.
3) Angle-type globe valve American standard bellows globe valve ZDAJ41W stainless steel body
In a check valve, the fluid only needs to change its direction once, so that the pressure drop through the valve is smaller than that of a conventional stop valve.
4) Plunger globe valve: This type of globe valve is a variant of a conventional globe valve. In this valve, the disc and seat are usually designed based on the plunger principle. The valve flap is polished so that the plunger is connected to the valve stem, and the sealing is achieved by two elastic sealing rings sleeved on the plunger. The two elastic sealing rings are separated by a collar, and the sealing ring around the plunger is firmly pressed by the load applied to the bonnet by the bonnet nut. The elastic sealing ring can be replaced and can be made of various materials. The valve is mainly used for "on" or "off", but a special form of plunger or special collar is also available to adjust the flow .
Location of the thread on the stem
1) Upper threaded stem globe valve: the thread of the stem of the globe valve Shut-off valve
Outside the valve body. The advantage is that the valve stem is not affected by the medium and is easy to lubricate. This structure is widely used.
2) Lower threaded stem stop valve: The thread of the stop valve stem is in the valve body. This structure of the valve stem thread is in direct contact with the medium, is susceptible to erosion and cannot be lubricated. This structure is used in places with small caliber and low temperature.
There are many domestic manufacturers of globe valves, and most of the connection sizes are not uniform. Mainly divided into the following categories: JB / T2203-1999 "Seal Valve Structure Length" is a general category. At present, most domestic stop valve manufacturers are designed and produced according to this standard. However, this standard is not perfect, and the specifications are not complete. The maximum nominal diameter of a single gate globe valve is DN1200, and the maximum nominal diameter of a double gate globe valve is DN1500. According to the specifications of the globe valve produced by the manufacturer and the information available, the minimum nominal diameter of the angle globe valve is DN15, and the nominal diameter of the Z-type straight through globe valve reaches DN2000. After verification, the connection sizes of various manufacturers are not uniform. In order to have a unified standard, the same specifications can be interchanged when the user selects and installs it. It is recommended that China General Machinery Research Institute revise JB / T2203-1999 "Stop Valve Structure Length". It is recommended that design institutes and users choose according to standards, and globe valve manufacturers design and manufacture according to standards.
Globe valve according to application
Globe valve (12 photos)
Fluorine-lined shut-off valves are suitable for aqua regia, sulfuric acid, hydrochloric acid, hydrofluoric acid and various organic acids, strong acids, strong oxidants at -50 to 150 ° C, and are also suitable for strong alkali organic solvents of various concentrations and other For corrosive gas and liquid medium.
The national standard globe valve is the most commonly used product in the globe valve series. The American standard globe valve implements ANSI and API standards. The sealing surface of the valve disc and valve seat is made of Stellite cobalt-based hard metal with different hardness. The alloy is made by surfacing, with reliable sealing, high hardness, abrasion resistance, high temperature resistance, corrosion resistance, good abrasion resistance and long life.
Needle valve is a small-caliber instrument valve, which plays a role of opening and closing and precise flow control in the instrument measuring pipeline system. It mainly includes power station instrument series, oilfield special series, American standard series, etc.
Low temperature cut-off valve usually refers to the valve whose working temperature is lower than -110 , which is widely used in liquefied natural gas, liquefied petroleum gas and other low-temperature industries. From 2008, it is possible to manufacture globe valves suitable for temperatures up to -196 ° C. All parts are pre-treated with liquid nitrogen at low temperature to completely avoid leakage of seal deformation during use.
The plunger valve is also known as the plunger stop valve. Its sealing surface adopts a radial seal structure. The two elastic sealing rings sleeved on the polished plunger apply the load on the bonnet by the load bolt on the bonnet through the valve body and bonnet. The elastic sealing ring around the plug is pressed to achieve a sealed stop valve.
The insulation jacket cut-off valve adopts the insulation jacket design, and the external heat source is used to circulate heat outside the valve, which can effectively prevent the temperature loss when the medium passes through the valve and ensure the temperature of the medium.
Forged steel globe valve is designed and manufactured according to API 602 standard. It provides three bonnet design forms: bolt bonnet, welded bonnet, pressure self-tight sealing bonnet. Users can choose different forms according to their needs. Provide RF flange, NPT thread, SW welding type three connection methods.
The special oxygen stop valve is made of silicon brass or stainless steel with excellent material, which has the advantages of high mechanical strength, wear resistance and good safety. Used on oxygen pipelines, it has the best explosion-proof and flame-retardant performance, eliminates unsafe factors on the oxygen pipelines, and is widely used in steel, metallurgy, petrochemical, chemical and other oxygen engineering pipeline networks. In addition to the functions of ordinary valves, it also has its own characteristics. Strict oil-free measures are adopted during manufacturing, and all parts are strictly degreased before installation.
The bellows globe valve adopts the shape of stainless steel bellows design. The bellows reciprocating test is 10,000 times without failure. The sealing performance is reliable. It is suitable for industrial and mining with flammable and explosive, toxic and harmful media, which can effectively prevent the valve from leaking.
Comparison of globe valve products
Comparison of bellows globe valve and ordinary globe valve
1. Double sealing design (corrugated pipe + packing) If the bellows fails, the valve stem packing will also avoid leakage and meet international sealing standards.
2. No fluid loss, reducing energy loss and improving plant equipment safety.
3. Long service life, reducing maintenance times and operating costs.
4. The durable and durable bellows seal design guarantees zero leakage of the valve stem and provides maintenance-free conditions.
5, gas medium valve seat using PTFE soft sealing material to improve the tightness of the valve.
6. High temperature resistance 425 ° C valve seat adopts tapered hard seal. Achieve zero airtight performance.
As labor costs continue to rise, mitigating labor is what more and more companies want. Having such a bellows globe valve makes it easier for workers to switch on and off. Products have a longer life and better sealing performance. There is reason to believe it. The prospects will become wider and wider.
Electric
Features of electric globe valve
1. The fluid resistance is small, and its resistance coefficient is equal to the pipe length of the same length.
2. Simple structure, small size and light weight. Electric globe valve
3 It is tight and reliable. The sealing surface material of the gate valve is widely used in plastic and has good sealing performance. It has also been widely used in vacuum systems.
4 Easy operation, fast opening and closing, only need to rotate 90 ° from fully open to fully closed, which is convenient for long-distance control.
5. Easy maintenance, simple structure of the gate valve, the seal ring is generally movable, and it is more convenient to remove and replace.
6. When fully open or fully closed, the sealing surfaces of the ball and valve seat are isolated from the medium, and the medium will not cause erosion of the valve sealing surface when the medium passes.
7. Wide range of application, from small diameter to several millimeters, large to several meters, from high vacuum to high pressure can be applied.
Classification of electric globe valve
According to the channel position, it can be divided into straight type and right angle type.
working principle
The working principle of the electric shut-off valve is to make the valve open or occluded by rotating the valve. The gate valve is lightweight, small in size, can be made into a large caliber, has a reliable seal, simple structure, and convenient maintenance. The sealing surface and the spherical surface are often in a closed state, which is not easy to be eroded by the medium.
A. Opening process
1 In the closed position, the valve body is tightly pressed on the valve seat by the mechanical pressure of the valve stem.
2 When the handwheel is turned counterclockwise, the valve stem moves in the opposite direction, and the angular plane at the bottom makes the ball release the valve seat.
3 The valve stem continues to lift, and interacts with the guide pin in the spiral groove of the valve stem, so that the ball starts to rotate without friction.
4 Until the fully open position, the valve stem is lifted to the extreme position, and the ball is rotated to the fully open position.
B. The closing process
1 When closed, turn the handwheel clockwise, the valve stem starts to lower and the ball leaves the valve seat and starts to rotate.
2 Continue to rotate the handwheel, the valve stem is affected by the guide pin embedded in the spiral groove on it, so that the valve stem and the gate rotate 90 ° at the same time.
3 When it is about to close, the gate body has been rotated 90 ° without contacting the valve seat.
4 In the last few turns of the hand wheel, the angular plane at the bottom of the valve stem is mechanically wedged to press the ball tightly against the valve seat to achieve a complete seal.
Structural features of electric globe valve:
1. No friction during opening and closing. This function completely solves the problem that the traditional valve affects the seal due to the friction between the sealing surfaces.
2. Top-loading structure. The valve installed on the pipeline can be directly checked and repaired online, which can effectively reduce the equipment shutdown and reduce costs.
3. Single valve seat design. Eliminates the problem that the medium in the cavity of the valve affects the safety of use due to abnormal pressure rise.
4. Low torque design. The valve stem with special structure design can be easily opened and closed with a small handle.
5. Wedge-shaped seal structure. The valve is sealed by the mechanical force provided by the valve stem, which presses the ball wedge against the valve seat, so that the sealing of the valve is not affected by the change in the pressure difference of the pipeline, and the sealing performance is reliably guaranteed under various working conditions.
6. Self-cleaning structure of sealing surface. When the sphere is tilted away from the valve seat, the fluid in the pipeline passes through the sealing surface of the sphere uniformly at 360 °, which not only eliminates the local erosion of the valve seat by the high-speed fluid, but also removes the accumulation on the sealing surface to achieve the purpose of self-cleaning. .
7. The valve body and valve cover below DN50 are die forgings, and the valve body and valve cover above DN65 are steel castings.
8. There are different connection forms between valve body and valve cover, clamp pin connection, flange gasket connection and self-sealing thread connection.
9. The sealing surfaces of the valve seat and valve disc are made of plasma spray welding or surfacing of cobalt chromium tungsten cemented carbide. The sealing surface has high hardness, wear resistance, abrasion resistance and long service life.
10. The material of the valve stem is nitriding steel. The surface of the valve stem after nitriding has high hardness, wear resistance, abrasion resistance, corrosion resistance and long service life.
Installation of electric globe valve
1. Pay attention to the flow direction of the medium when installing the valve, and install it strictly in the direction indicated by the valve flow direction arrow.
2. Any position of the pipeline where the valve can be installed, and at the same time choose the carbon steel or alloy steel valve according to the medium and the temperature of the medium.
3. Install the electric shut-off valve as vertically as possible, with the stem up.
Advantages and disadvantages of globe valves
Features
(1) The structure of globe valve is simpler than that of gate valve, and it is more convenient to manufacture and maintain.
(2) The sealing surface is not easy to wear and abrasions, and has good sealing performance. There is no relative sliding between the valve disc and the sealing surface of the valve body during opening and closing, so the wear and abrasion are not serious, the sealing performance is good, and the service life is long.
(3) When opening and closing, the travel of the valve flap is small, so the height of the stop valve is smaller than that of the gate valve, but the structure length is longer than that of the gate valve.
(4) The opening and closing torque is large, and the opening and closing is more laborious, and the opening and closing time is the principal.
(5) The fluid resistance is large, because the medium passage in the valve body is tortuous, the fluid resistance is large, and the power consumption is large.
(6) When the nominal pressure PN 16MPa in the flow direction of the medium, the forward flow is generally adopted, and the medium flows upward from the valve disc; when the nominal pressure PN 20MPa, the reverse flow is generally used, and the medium flows downward from the valve disc. To increase the seal capacity. In use, the medium of the shut-off valve can only flow in one direction, and the flow direction cannot be changed.
(7) The valve flap is often eroded when fully opened.
The stem axis of the globe valve is perpendicular to the seat sealing surface. The valve stem has a relatively short opening or closing stroke and has a very reliable shut-off action, making this valve suitable for use as a medium for cutting or regulating and throttling.
Disadvantage
1. Fluid resistance Bellows globe valve
The force is large, and the force required when opening and closing is large.
2. It is not suitable for media with particles, large viscosity and easy to coke.
3. Poor regulation performance.
advantage
1. Double sealing design (corrugated pipe + packing) If the bellow fails, the valve stem packing will also be avoided;
2. External leakage and meet international sealing standards;
3. No fluid loss, reducing energy loss and improving plant equipment safety;
4. Long service life, reducing maintenance times and operating costs;
5. The durable and durable bellows seal design guarantees zero leakage of the valve stem and provides maintenance-free conditions.
6. The bellows seal stop valve adopts the design of bellows seal, which completely eliminates the shortcomings of the common valve stem packing seals, such as aging, and easy to leak, which not only improves the use of energy efficiency, increases the safety of production equipment, reduces maintenance costs and frequent Maintenance also provides a clean and safe working environment.
Stop valve installation method
The installation and maintenance of globe valve should pay attention to the following:
1. Stop valves operated by handwheels and handles can be installed at any position in the pipeline.
2. Handwheel, handle and micro-movement mechanism are not allowed for lifting.
3. The flow direction of the medium should be consistent with the direction of the arrow shown on the valve body.
Stop valve main standard
1.GB/T 12233-2006 "General valve iron globe valve and lifting check valve"
2. GB / T 12235-2007 "General valve flange connection steel globe valve and lifting check valve"
3. JB / T53174-94 "Quality Rating of Globe Valve Products"
4, JB / T53165-92 "high pressure balanced globe valve"
5.GB/T 587-2008 "Marine flange bronze globe valve"
6.GB/T 590-2008 "Marine flange cast iron globe valve"
7, GB / T 8464-2008 "iron and copper threaded connection valve"
8. GB8465.2-87 "Internally threaded gate valve, globe valve, ball valve, check valve, basic size iron globe valve"
Stop valve related knowledge
A shut-off valve is a valve in which the closing member (valve) moves along the centerline of the seat. According to this type of movement of the valve disc, the change in the valve seat port is proportional to the valve stroke. Because this type of valve has a relatively short opening or closing stroke and a very reliable shut-off function, and because the change in valve seat opening is proportional to the stroke of the valve disc, it is very suitable for regulating flow. Therefore, this type of valve is very suitable for shut-off or regulating and throttling.
Selection principle
1. High-temperature and high-pressure medium pipelines or devices should use stop valves. Such as thermal power plant, nuclear power plant, petrochemical system high temperature, high pressure pipeline.
2. On pipelines where convection resistance is not strict. That is, where pressure loss is not considered.
3. Needle valve, instrument valve, sampling valve and pressure gauge valve can be used for small valves.
4. There are flow adjustment or pressure adjustment, but the accuracy of the adjustment is not high, and the diameter of the pipeline is relatively small. For a pipeline with a nominal through diameter of 50mm, it should be selected.
5. Small chemical fertilizers and large chemical fertilizers used in synthetic industrial production should choose high pressure angle globe valves or high pressure angle throttle valves with nominal pressure PN160 nominal pressure 16MPa or PN320 nominal pressure 32MPa.
6. In the desiliconization workshop and the coke-prone pipeline in the production of alumina Bayer method, it is easy to choose a DC-type globe valve or a DC-type throttle valve with separated valve body and removable valve seat.
7. In the water supply and heating projects in urban construction, the nominal passage is smaller, and the stop, balance valve or plunger valve can be selected, such as the nominal passage of less than 150mm.
During the opening and closing process, the valve disc is tight Structure diagram
The friction between the covers is less than that of the gate valve and is therefore wear-resistant. The opening height is generally only 1/4 of the diameter of the seat channel, so it is much smaller than the gate valve. Usually there is only one sealing surface on the valve body and valve disc, so the manufacturing process is better and it is easier to maintain.
Nominal pressure or pressure level: PN1.0-16.0MPa, ANSI CLASS 150-900, JIS10-20K Nominal diameter or caliber: DN10 500, NPS 1/2 36 "Connection method: flange, butt welding, thread, etc. Applicable temperature: -196 700 Drive mode: pneumatic, electric, hydraulic, gas-liquid linkage, valve body material: WCB, ZG1Cr18Ni9Ti, ZG1Cr18Ni12Mo2Ti, CF8 (304), CF3 (304L), CF8M (316), CF3M (316L), Ti. Different materials are used, which can be applied to various media such as water, steam, oil, nitric acid, acetic acid, oxidizing media, urea, etc.
Shut-off valve operation
For globe valves, not only will they be installed and maintained, but they will also be operated.
Open and close the shut-off valve, the force should be stable and not impact. Some parts of the high-pressure shut-off valve that have been opened and closed by shock have considered that this kind of impact force is not equivalent to the ordinary shut-off valve.
When the shut-off valve is fully open, the handwheel should be turned upside down a little to tighten the threads tightly to avoid loose damage.
When the pipeline is used for the first time, there is a lot of internal dirt. You can slightly open the shut-off valve, use the high-speed flow of the medium, flush it away, and then close it gently (cannot be closed quickly or violently to prevent the sealing surface from being trapped by residual impurities) , Turn it on again, repeat this many times, rinse the dirt, and then put it back into normal work.
Normally open shut-off valve, there may be dirt on the sealing surface, when it is closed, it must be flushed clean with the above method, and then closed formally.
If the handwheel or handle is damaged or lost, it should be equipped immediately. It can not be replaced by a flexible wrench, so as not to damage the four sides of the valve stem, opening and closing failure, and an accident in production.
Some media are cooled after the shut-off valve is closed to shrink the valve, and the operator should close it again at an appropriate time so that there are no fine seams on the sealing surface. Otherwise, the medium flows at high speed through the fine seams and it is easy to erode the seal. surface.
During operation, if it is found that the operation is too laborious, the cause should be analyzed. If the packing is too tight, it can be properly relaxed. If the valve stem is skewed, the personnel should be notified to repair it. In some shut-off valves, when the closing part is heated, the closing member expands due to heat, which makes it difficult to open; if it must be opened at this time, the valve cover can be loosened by half a turn to one turn to eliminate the valve stem stress, and then the handwheel is moved.
Globe valve torque analysis
At the stage when the shut-off valve starts to close from the fully open position, as the disc is lowered, the fluid causes a pressure difference before and after the disc to prevent the disc from descending, and this resistance increases rapidly as the disc is lowered. When the shut-off valve is fully closed, the pressure difference between the front and back of the disc is equal to the working pressure of the medium. At this time, the resistance is the largest. In addition to the forced sealing force, the operating force at the moment of closing the shut-off valve increases quickly. During the valve opening process, the thrust caused by the pressure of the medium or the pressure difference between the front and back of the valve flap helps to open the valve. It should be pointed out that the moment at the moment of opening the valve may exceed the moment at the moment of closing the valve, because a larger static friction force must be overcome at this time. When the shut-off valve is opened, when the opening height of the flap reaches 25% to 30% of the nominal diameter of the shut-off valve, the flow rate has reached the maximum, indicating that the shut-off valve has reached the fully open position, so the fully open position of the shut-off valve should be determined by the flap Itinerary to determine. The situation when the shut-off valve is closed and re-opened after it is closed is similar to that of a forced-sealed gate valve. Therefore, the closed position of the shut-off valve should be determined by increasing the operating torque to a specified value.
Globe valve works
The shut-off valve only allows the medium to flow in one direction, and it is directional during installation. The structural length of the globe valve is longer than that of the gate valve. At the same time, the fluid resistance is large. During long-term operation, the sealing reliability is not strong.
There are three types of globe valves: straight-through globe valves, right-angle globe valves, and DC oblique globe valves.
The most obvious advantage is that during the opening and closing process, the friction between the valve disc and the sealing surface of the valve body is smaller than that of the gate valve, so it is wear-resistant. The opening height is generally only 1/4 of the diameter of the seat channel, so it is much smaller than the gate valve. Usually there is only one sealing surface on the valve body and valve disc, so the manufacturing process is better and it is easier to maintain.
Stop valve nominal pressure or pressure level: PN1.0-16.0MPa, ANSICLASS150-900, JIS10-20K, nominal diameter or caliber: DN10 ~ 500, NPS1 / 2 ~ 36 ", stop valve connection method: flange, butt welding , Thread, etc., applicable temperature: -196 ~ 700 , stop valve driving mode: manual, bevel gear transmission, pneumatic, electric, hydraulic, gas-hydraulic linkage, electro-hydraulic linkage, valve body material: WCB, ZG1Cr18Ni9Ti, ZG1Cr18Ni12Mo2Ti, CF8 (304), CF3 (304L), CF8M (316), CF3M (316L), Ti. The globe valve is made of different materials.
The selection principle of globe valve is:
1. High-temperature, high-pressure medium pipelines or devices should choose stop valves. Such as thermal power plant, nuclear power plant, petrochemical system high temperature, high pressure pipeline.
2. On pipelines where convection resistance is not strict. That is, where pressure loss is not considered.
3. Needle valve, instrument valve, sampling valve, pressure gauge valve can be used for small valves.
4. There are flow adjustment or pressure adjustment, but the accuracy of the adjustment is not high, and the diameter of the pipeline is relatively small, such as the nominal through the pipeline 50mm, it should be used.
5. Small chemical fertilizers and large chemical fertilizers in synthetic industrial production should choose high pressure angle globe valve or high pressure angle globe valve with nominal pressure PN160 nominal pressure 16MPa or PN320 nominal pressure 32MPa.
6. In the desiliconization workshop and the coke-prone pipeline in the production of alumina Bayer method, it is easy to choose a DC-type globe valve or a DC-type globe valve with a separated valve body and a removable seat, and a hard alloy sealing pair.
7. For urban water supply and heating projects, the nominally passing small pipelines can be used with stop valves, balancing valves or plunger valves, such as those with nominally passing pipelines smaller than 150mm.
Globe valve maintenance
The shut-off valve in operation should be complete and intact. The bolts on the flange and the bracket are indispensable, and the threads should be intact and no looseness is allowed. The tightening nut on the handwheel should be tightened in time if looseness is found, so as not to wear the connection or lose the handwheel and nameplate. If the handwheel of the shut-off valve is lost, it is not allowed to use a spanner to replace it. Packing glands must not be skewed or have no pre-tensioning gap. For globe valves that are susceptible to contamination by rain, snow, dust, wind and sand, the valve stem should be equipped with a protective cover. The scale on the stop valve should be kept complete, accurate and clear. Seals, caps, pneumatic accessories, etc. of the globe valve should be complete. It is not allowed to knock, stand on or support heavy objects on the shut-off valve in operation; especially for non-metallic valves and cast iron valves, it is also forbidden to perform maintenance work on the valve during grease injection. Before welding and before putting into operation, professional valve maintenance Serving the valve in the production and operation plays a vital role. Correct and orderly and effective maintenance will protect the valve, make the valve function properly and prolong the service life of the valve. Valve maintenance may seem simple, but it is not. There are often neglected aspects of work.
First, the problem of the amount of fat injection is often overlooked when the globe valve is filled with fat. After refueling, the operator selects the valve and the way of refueling and then performs refueling. There are two situations: On the one hand, the amount of grease injected is small, and the amount of grease injected is insufficient, and the sealing surface is accelerated due to lack of lubricant. On the other hand, excessive fat injection causes waste. The reason is that there is no accurate calculation of the sealing capacity of different shut-off valves according to the type of valve. The sealing capacity can be calculated based on the size and type of the shut-off valve, and then a reasonable amount of grease can be injected.
Second, the pressure problem is often ignored when the globe valve is filled with grease. During the fat injection operation, the fat injection pressure changed regularly in peaks and valleys. The pressure is too low, the seal leaks or fails, the pressure is too high, the grease injection port is blocked, the grease in the seal is hardened, or the seal ring is locked with the valve ball and valve plate. Usually when the grease injection pressure is too low, the injected grease flows into the bottom of the valve cavity, which usually occurs in small gate valves. The grease injection pressure is too high. On the one hand, check the grease injection nozzle, and replace it if the fat hole is blocked. . In addition, the seal type and seal material also affect the grease injection pressure. Different seal types have different grease injection pressures. Generally, the hard seal grease injection pressure is higher than the soft seal. The ball valve is generally in the open position during maintenance. In special cases, the valve is closed for maintenance. Other valves cannot be treated in the same way. The gate valve must be closed during maintenance to ensure that the grease fills the sealing groove along the seal ring. If it is open, the seal grease will fall directly into the flow channel or valve cavity, causing waste.
After installation, the globe valve should be inspected regularly. The main inspection items are:
(1) Wear of sealing surface of globe valve.
(2) Wear of trapezoidal threads on the stem and stem nut.
(3) Whether the packing is out of date and should be replaced in time if damaged.
(4) After maintenance and assembly of the shut-off valve, a seal performance test shall be performed.
Globe valve performance parameters
J41H cast steel flange globe valve product shape and structure size and weight 1.6MPa
DN | L | D | D1 | D2 | b | z × ød | H | D0 | Weight / KG |
10 | 130 | 90 | 60 | 40 | 14 | 4 × ø14 | 198 | 120 | 5 |
15 | 130 | 95 | 65 | 45 | 14 | 4 × ø14 | 200 | 120 | 5.5 |
20 | 150 | 105 | 75 | 55 | 14 | 4 × ø14 | 243 | 140 | 7.3 |
25 | 160 | 115 | 85 | 65 | 14 | 4 × ø14 | 253 | 160 | 8 |
32 | 180 | 135 | 100 | 78 | 15 | 4 × ø18 | 280 | 160 | 12 |
40 | 200 | 145 | 110 | 85 | 16 | 4 × ø18 | 312 | 200 | 16 |
50 | 230 | 160 | 125 | 100 | 16 | 4 × ø18 | 321 | 200 | 16 |
65 | 290 | 180 | 145 | 120 | 18 | 4 × ø18 | 325 | 240 | twenty two |
80 | 310 | 195 | 160 | 135 | 20 | 4 × ø18 | 355 | 240 | 31 |
100 | 350 | 215 | 180 | 155 | 20 | 4 × ø18 | 415 | 280 | 45 |
125 | 400 | 245 | 210 | 185 | twenty two | 4 × ø18 | 460 | 320 | 80 |
150 | 480 | 280 | 240 | 210 | twenty four | 8 × ø23 | 510 | 360 | 97 |
200 | 600 | 335 | 295 | 265 | 26 | 12 × ø23 | 590 | 360 | 169 |
J41H cast steel flange globe valve product shape and structure size and weight 2.5MPa
DN | L | D | D1 | D2 | b | z × ød | H | D0 | Weight / KG |
10 | 130 | 90 | 60 | 40 | 16 | 4 × ø14 | 198 | 120 | 4.9 |
15 | 130 | 95 | 65 | 45 | 16 | 4 × ø14 | 233 | 120 | 5.5 |
20 | 150 | 105 | 75 | 55 | 16 | 4 × ø14 | 275 | 140 | 7 |
25 | 160 | 115 | 85 | 65 | 16 | 4 × ø14 | 285 | 160 | 7.5 |
32 | 180 | 135 | 100 | 78 | 18 | 4 × ø18 | 302 | 180 | 8.5 |
40 | 200 | 145 | 110 | 85 | 18 | 4 × ø18 | 355 | 200 | 12.5 |
50 | 230 | 160 | 125 | 100 | 20 | 4 × ø18 | 362 | 240 | 16 |
65 | 290 | 180 | 145 | 120 | twenty two | 8 × ø18 | 325 | 280 | 25 |
80 | 310 | 195 | 160 | 135 | twenty two | 8 × ø18 | 369 | 280 | 30 |
100 | 350 | 230 | 190 | 165 | twenty four | 8 × ø23 | 370 | 300 | 35 |
125 | 400 | 270 | 220 | 188 | 28 | 8 × ø18 | 558 | 400 | 89 |
150 | 480 | 300 | 250 | 218 | 30 | 8 × ø23 | 611 | 400 | 98 |
200 | 600 | 360 | 310 | 278 | 34 | 12 × ø25 | 721 | 400 | 170 |
J41H cast steel flange globe valve product shape and structure size and weight 4.0MPa
DN | L | D | D1 | D2 | b | z × ød | H | D0 | Weight / KG |
10 | 130 | 90 | 60 | 40 | 16 | 4 × ø14 | 198 | 120 | 4.5 |
15 | 130 | 95 | 65 | 45 | 16 | 4 × ø14 | 233 | 120 | 5 |
20 | 150 | 105 | 75 | 55 | 16 | 4 × ø14 | 275 | 140 | 7 |
25 | 160 | 115 | 85 | 65 | 16 | 4 × ø14 | 285 | 160 | 9 |
32 | 180 | 135 | 100 | 78 | 18 | 4 × ø18 | 302 | 160 | 12 |
40 | 200 | 145 | 110 | 85 | 18 | 4 × ø18 | 355 | 200 | 17 |
50 | 230 | 160 | 125 | 100 | 20 | 4 × ø18 | 373 | 240 | twenty four |
65 | 290 | 180 | 145 | 120 | twenty two | 8 × ø18 | 408 | 280 | 33 |
80 | 310 | 195 | 160 | 135 | twenty two | 8 × ø18 | 436 | 320 | 44 |
100 | 350 | 230 | 190 | 160 | twenty four | 8 × ø23 | 480 | 360 | 60 |
125 | 400 | 270 | 220 | 188 | 28 | 8 × ø25 | 558 | 400 | 89 |
150 | 480 | 300 | 250 | 218 | 30 | 8 × ø25 | 611 | 400 | 130 |
