Globe valve analysis and process flow
2021-11-20 13:06:28
The opening and closing member of the stop valve (GlobeValve) is a plug-shaped valve flap with a flat or tapered surface, and the valve disc moves linearly along the center line of the valve seat. The movement form of the valve stem (general name: dark rod), also has the lifting rotary rod type, (common name: bright rod) the stop valve refers to the valve that the closing member (valve) moves along the center line of the valve seat. Depending on the form of movement of the flap, the change in the seat opening is proportional to the flap travel. Due to the relatively short opening or closing stroke of the valve stem of this type of valve, and the very reliable cutting function, and because the change of the valve seat opening is proportional to the stroke of the valve flap, it is very suitable for the adjustment of the flow rate. Therefore, this type of shut-off globe valve is well suited for shut-off or regulation and throttling.
The shut-off valve is a forced-sealed valve, so when the valve is closed, pressure must be applied to the valve flap to force the sealing surface to leak. When the medium enters the valve from below the valve flap, the resistance to be overcome by the operating force is the friction between the stem and the packing and the thrust generated by the pressure of the medium. The force of closing the valve is greater than the force of opening the valve, so the valve stem The diameter of the stem should be large, otherwise the valve stem can be bent. There are three types according to the connection method: flange connection, thread connection, and welding connection. In recent years, after the appearance of the self-sealing valve, the medium flow direction of the shut-off valve is changed into the valve chamber from above the valve flap. At this time, under the action of the medium pressure, the force of closing the valve is small, and the force of opening the valve is large, the valve stem is The diameter can be reduced accordingly. At the same time, this type of valve is also tight under the action of the medium. China's valve "three-way to give" has stipulated that the flow of the stop valve, all from top to bottom. When the valve is to be installed horizontally, the opening height of the valve flap is 25% to 30% of the nominal diameter. The flow rate has reached a large value, indicating that the valve has reached the fully open position. Therefore, the full open position of the shutoff valve should be determined by the stroke of the valve flap. The shut-off valve, also called the cut-off valve, is a kind of valve that uses zui extensively. It is popular because of the small friction between the sealing surfaces during the opening and closing process, which is relatively durable, the opening height is not large, the manufacturing is easy, and the maintenance is easy. Convenient, not only for medium and low pressure, but also for high pressure.
The closing principle of the shut-off valve is that, relying on the pressure of the valve bar, the sealing surface of the valve disc and the sealing surface of the valve seat are closely fitted to prevent the medium from flowing.
The shut-off valve allows only one-way flow of the medium and is directional when installed. The structural length of the shut-off valve is larger than that of the gate valve, and the fluid resistance is large. When the machine is operated for a long time, the sealing reliability is not strong.
1) Straight-through globe valve 2) DC-type globe valve: In the DC or Y-shaped globe valve, the flow path of the valve body is inclined with the main flow channel, so that the flow state is less damaged than the conventional globe valve, so The pressure loss of the valve is also correspondingly small.
3) Angle stop valve: In the angle cut-off valve, the fluid only needs to change in one direction, so that the pressure drop through the valve is smaller than that of the conventional structure.
American standard bellows stop valve ZDAJ41W type 4) Plunger type stop valve: This type of stop valve is a variant of the conventional stop valve. In this valve, the flap and seat are usually designed based on the principle of the plunger. The valve flap is polished into a plunger that is coupled to the valve stem, and the seal is achieved by two elastomeric sealing rings that are placed over the plunger. The two elastomeric seals are separated by a collar and the seal around the plunger is pressed by the load exerted by the bonnet nut on the bonnet. The elastomeric seal can be replaced and can be made from a wide variety of materials. The valve is mainly used for "opening" or "off", but with a special form of plunger or special collar, it can also be used to regulate flow. . Position of the thread on the stem 1) Upper threaded stem stop valve: The thread of the shutoff valve stem is outside the valve body. The advantage is that the valve stem is not eroded by the medium and is easy to lubricate, and such a structure is relatively common.
2) Lower threaded stem stop valve: The thread of the shutoff valve stem is inside the valve body. This type of stem thread is in direct contact with the media and is susceptible to erosion and lubrication. This structure is used in places with small calibers and low temperatures.
There are many manufacturers of shut-off valves in China, and the connection sizes are mostly not uniform. Mainly divided into the following major categories:
1) General class based on JB/T2203-1999 "Structural length of shut-off valve". At present, most domestic safety valve manufacturers are designed and produced according to this standard. Such as Hailai Le Valve Co., Ltd., Zhejiang Luofu Boiler Accessories Factory, Hangzhou Stop Valve Factory, Shanghai Liangzhong Valve Co., Ltd., Shanghai Cut-off Valve Factory, Kaifeng High Pressure Globe Valve Factory, Hai'an Globe Valve Factory, etc. However, this standard is not perfect, the specifications are not complete, single gate stop valve zui large nominal diameter is DN1200, double gate cut-off valve zui large nominal diameter DN1500. According to the specifications of the shut-off valve produced by the factory and the information obtained, the nominal diameter of the angle cut-off valve is DN15, and the nominal diameter of the Z-type straight-through stop valve reaches DN2000. According to the research, the connection sizes of various manufacturers are not uniform. For example, the DN150Z straight-through globe valve, Shanghai Liangzhong Valve Factory, Shanghai Globe Valve Factory and Shanghai Yaze Valve Factory are all different. In order to have a uniform standard, the user can exchange the same specifications during the selection and installation. It is recommended that China General Machinery Research Institute revise JB/T2203-1999 "Structure Length of Globe Valve". It is recommended that the design institute and users choose according to the standard, and the manufacturer of the globe valve is designed and manufactured according to the standard.
The organic aqua regia, sulfuric acid, hydrochloric acid, hydrofluoric acid and various uses of fluorine <br> <br> lined shut-off valve in the shut-off valve suitable for -50 ~ 150 ℃ various concentrations, strong acids, strong oxidants, further Suitable for use in various concentrations of strong alkali organic solvents and other corrosive gases, liquid media.
API American standard cut-off valve American standard cut-off valve performs ANSI and API standards. The sealing surface of the valve disc and seat is made of Slite cobalt-based hard alloy with different hardness. The seal is reliable, high hardness and resistant. Grinding, high temperature resistance, corrosion resistance, good scratch resistance and long life.
The national standard stop valve is the commonly used product of the cut-off valve series. The sealing surface of the valve seat and the valve disc is made of Slite cobalt-based hard alloy with different hardness. The seal is reliable and the hardness is high. Wear resistance, high temperature resistance, corrosion resistance, good scratch resistance and long life.
Needle-type valve needle valve is a small-diameter 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, oil field special series and American standard series.
Low temperature shut-off valves Low temperature shut-off valves are generally referred to as valves operating at temperatures below -110 ° C and are widely used in liquefied natural gas, liquefied petroleum gas and other cryogenic industries. At present, it is possible to manufacture a shut-off valve with a temperature of -196 ° C. All parts are treated with liquid nitrogen for low temperature pretreatment, completely avoiding sealing deformation and leakage during use.
The plunger valve plunger valve, also known as the plunger stop valve, has a sealing surface with a radial sealing structure, and two elastic sealing rings sleeved on the polishing plunger are applied to the valve cover through the connecting bolts of the valve body and the valve cover. The load presses the elastomeric seal around the plunger to seal the shutoff valve.
<br> <br> insulation jacket insulation jacket cut valve globe valve design insulation jacket, external heat source in the external circulation of the valve, the medium can be effectively prevented when the temperature loss through the valve, to ensure the temperature of the medium.
<br> <br> forged steel forged steel cut-off valve shut-off valve in accordance with design and manufacturing standards API602, a valve cover design provides three forms: bonnet bolted, welded valve cover, a pressure tight seal from the valve cover, the user can choose according to need Different forms, RF flange, NPT thread, SW welding type are available.
For oxygen shut-off valve for oxygen shut-off valve <br> <br> use of fine silicon material cast from brass or stainless steel, having high mechanical strength, wear resistance, and good safety. Used in the oxygen pipeline, it has excellent explosion-proof flame retardant performance, eliminating the unsafe factors on the oxygen pipeline, and is widely used in the pipe network of oxygen, steel, metallurgy, petrochemical, chemical and other oxygen projects. In addition to the function of ordinary valves, it has its own characteristics. Strict oil-free measures are taken during manufacturing and all parts are strictly degreased prior to installation.
<br> <br> bellows valve bellows valve formed using stainless steel bellows design, the bellows Test reciprocating 10,000 times without failure, a reliable sealing performance for explosive, toxic and hazardous industrial medium can be effectively Prevent leakage of the valve.
Advantages 1. Simple structure, convenient manufacturing and maintenance.
2. The working stroke is small and the opening and closing time is short.
3, good sealing, small friction between sealing surfaces, long life.
4. The structure of the shut-off valve body is straight-through, direct-flow and right-angle. Straight-through is a common structure of Zui, but its fluid resistance is large. DC fluid resistance is small, and it is mostly used for fluids containing solid particles or high viscosity. The right angle valve body is mostly forged, suitable for small through, high pressure shut-off valves.
5. The frictional force of the sealing surface is smaller and more wear-resistant than the gate valve during the opening and closing process.
6, usually only one sealing surface, good manufacturing process, easy to repair. Disadvantages 1. The fluid resistance is large, and the force required for opening and closing is large.
2. It is not suitable for media with particles, high viscosity and easy coking.
3. The adjustment performance is poor.
4. The type of shut-off valve is divided into external thread type and internal thread type according to the position of the stem thread. According to the flow direction of the medium, there are straight-through, direct-current and angular. The shut-off valve is divided into seals, with a packing seal shut-off valve and a bellows seal shut-off valve.
5. The bellows seal stop valve adopts the design of the bellows seal, completely eliminating the shortcomings of the normal valve stem packing seal aging and easy to leak, not only improving the energy efficiency, increasing the safety of the production equipment, reducing the maintenance cost and frequent Maintenance and maintenance also provides a clean and safe working environment.
Advantages of use 1. Double seal design (corrugated pipe + packing) If the bellows fails, the stem packing will also be avoided;
2, external leakage, and in line with international sealing standards;
3. No fluid loss, reduce energy loss, and improve plant equipment safety;
4, long service life, reduce the number of maintenance, reduce operating costs;
5, rugged bellows seal design, to ensure zero leakage of the valve stem, providing maintenance-free conditions.
The type of the shut-off valve is divided into an external thread type and an internal thread type according to the position of the stem thread. According to the flow direction of the medium, there are straight-through, direct-current and angular. The shut-off valve is divided into seals, with a packing seal shut-off valve and a bellows seal shut-off valve.
The structural form of the stop valve:
The structure of the shut-off valve body is straight-through, direct-flow and right-angle. Straight-through is a common structure of Zui, but its fluid resistance is large. DC fluid resistance is small, and it is mostly used for fluids containing solid particles or high viscosity. The right angle valve body is mostly forged, suitable for small through, high pressure shut-off valves.
The following items should be noted for the installation and maintenance of the shut-off valve:
1. The handwheel and handle operated shut-off valve can be installed at any position of the pipeline.
2. Handwheels, handles and aerodynamic mechanisms are not allowed to be used for lifting.
3. The flow direction of the medium should be consistent with the direction of the arrow shown in the valve body.
The main criteria for the globe valve:
1. GB/T12233-2006 "Universal Valve Iron Globe Valve and Lifting Check Valve"
2, GB/T12235-2007 "Universal valve flange connection steel shut-off valve and lift check valve"
3, JB/T53174-94 "cut-off valve product quality classification"
4. JB/T53165-92 "High Pressure Balance Globe Valve"
5, GB/T587-2008 "Marine flanged valve for marine flanges"
6, GB/T590-2008 "Marine flanged cast iron globe valve"
7, GB/T8464-2008 "iron and copper threaded connection valve"
8, GB8465.2-87 "internal thread connection gate valve, globe valve, ball valve, check valve basic size iron shut-off valve"
1. GB/T12233-2006 "General-purpose valve iron globe valve and lift check valve" 2. GB/T12235-2007 "Universal valve flange connection steel globe valve and lift check valve" 3. JB/T53174- 94 "cut-off valve product quality classification" 4, JB/T53165-92 "high pressure balance cut-off valve" 5, GB/T587-2008 "marine flange flanged valve" 6, GB/T590-2008 "Marine flange cast iron cut-off Valve"7, GB/T8464-2008 "iron and copper threaded connection valve" 8, GB8465.2-87 "internal thread connection gate valve, globe valve, ball valve, check valve basic size iron shut-off valve" cut-off valve related A knowledge stop valve is a valve that moves a closure (valve) along the centerline of the seat. Depending on the form of movement of the flap, the change in the seat opening is proportional to the flap travel. Due to the relatively short opening or closing stroke of the valve stem of this type of valve, and the very reliable cutting function, and because the change of the valve seat opening is proportional to the stroke of the valve flap, it is very suitable for the adjustment of the flow rate. Therefore, this type of valve is well suited for use as a cut or adjustment and throttling. The selection principle is as follows: 1. The shut-off valve should be used on the pipeline or device of high temperature and high pressure medium. Such as thermal power plants, nuclear power plants, high-temperature, high-pressure pipelines of petrochemical systems. 2. On the pipeline where the flow resistance is not strict on the pipeline. That is, the place where the pressure loss is not considered. 3. Small valves can be used with needle valves, instrument valves, sampling valves, pressure gauge valves, etc. 4, there are flow regulation or pressure regulation, but the adjustment accuracy is not high, and the pipeline diameter is relatively small, such as the nominal diameter of ≤ 50mm pipeline, should be used. 5. For small chemical fertilizers and large chemical fertilizers in synthetic industrial production, high-pressure angle shut-off valves or high-pressure angle throttle valves with nominal pressure PN160 nominal pressure 16MPa or PN320 nominal pressure 32MPa should be used. 6. In the desiliconization workshop and the easy coking pipeline in the production of alumina Bayer method, it is easy to select the DC type shut-off valve or the DC type throttle valve with the valve body separated, the valve seat can be removed, and the carbide seal pair. 7. In the water supply and heating projects in urban construction, it is known to pass through smaller pipelines, and the cut-off, balance valve or plunger valve can be used, such as the pipeline passing the nominal less than 150mm. The obvious advantage of zui is that during the opening and closing process, the friction between the valve flap 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 and therefore much smaller than the gate valve. Usually there is only one sealing surface on the valve body and the valve flap, so the manufacturing process is better and easy to repair. Nominal pressure or pressure level: PN1.0-16.0MPa, ANSICLASS150-900, JIS10-20K nominal diameter or caliber: DN10～500, NPS1/2～36" Connection: flange, butt welding, thread, etc. -196°C～700°C Driving mode: pneumatic, electric, hydraulic, gas-liquid linkage, valve body materials: WCB, ZG1Cr18Ni9Ti, ZG1Cr18Ni12Mo2Ti, CF8(304), CF3(304L), CF8M(316), CF3M(316L) , Ti. Choose different materials, which can be applied to water, steam, oil, nitrate, acetic acid, oxidizing medium, urea and other media.
For the shut-off valve, not only will it be installed and maintained, but it will also operate.
To open and close the shut-off valve, the force should be stable and not impact. Some components of the high pressure shut-off valve that have been opened and closed have been considered such that the impact force is not equivalent to a general globe valve.
When the shut-off valve is fully open, the handwheel should be reversed a little to make the threads tightly tight to avoid loose damage.
When the pipeline is used initially, there is a lot of internal dirt. The shut-off valve can be slightly opened, and the high-speed flow of the medium is used to wash it away, and then it is gently closed (cannot be closed quickly and violently closed to prevent residual impurities from pinching the sealing surface) , turn it on again, repeat this many times, flush the dirt, and put it into normal work.
Normally open the shut-off valve, the sealing surface may be stuck with dirt, and when it is closed, it should be washed clean by the above method, and then officially closed.
If the handwheel or handle is damaged or lost, it should be immediately equipped. It should not be replaced by a live wrench, so as not to damage the valve stem, and the opening and closing is not working, resulting in an accident in production.
Some media, after the shut-off valve is closed, cool, so that the valve member shrinks, the operator should close again at the appropriate time, so that the sealing surface does not leave a slit, otherwise the medium flows through the slit at high speed, it is easy to erode the seal. surface.
When operating, if you find that the operation is too laborious, you should analyze the cause. If the packing is too tight, it can be properly relaxed. If the valve stem is skewed, the person should be notified to repair it. In some closed valves, the closing member is heated and expanded, which makes opening difficult; if it must be opened at this time, the bonnet thread can be loosened half a turn to one turn, the stem stress is eliminated, and then the hand wheel is driven.
The shut-off valve is a forced-sealed valve, so when the valve is closed, pressure must be applied to the valve flap to force the sealing surface to leak. When the medium enters the valve from below the valve flap, the resistance to be overcome by the operating force is the friction between the stem and the packing and the thrust generated by the pressure of the medium. The force of closing the valve is greater than the force of opening the valve, so the valve stem The diameter of the stem should be large, otherwise the valve stem can be bent. There are three types according to the connection method: flange connection, thread connection, and welding connection. In recent years, after the appearance of the self-sealing valve, the medium flow direction of the shut-off valve is changed into the valve chamber from above the valve flap. At this time, under the action of the medium pressure, the force of closing the valve is small, and the force of opening the valve is large, the valve stem is The diameter can be reduced accordingly. At the same time, this type of valve is also tight under the action of the medium. China's valve "three-way to give" has stipulated that the flow of the stop valve, all from top to bottom. When the valve is to be installed horizontally, the opening height of the valve flap is 25% to 30% of the nominal diameter. The flow rate has reached a large value, indicating that the valve has reached the fully open position. Therefore, the full open position of the shutoff valve should be determined by the stroke of the valve flap. The shut-off valve, also called the cut-off valve, is a kind of valve that uses zui extensively. It is popular because of the small friction between the sealing surfaces during the opening and closing process, which is relatively durable, the opening height is not large, the manufacturing is easy, and the maintenance is easy. Convenient, not only for medium and low pressure, but also for high pressure.
The closing principle of the shut-off valve is that, relying on the pressure of the valve bar, the sealing surface of the valve disc and the sealing surface of the valve seat are closely fitted to prevent the medium from flowing.
The shut-off valve allows only one-way flow of the medium and is directional when installed. The structural length of the shut-off valve is larger than that of the gate valve, and the fluid resistance is large. When the machine is operated for a long time, the sealing reliability is not strong.
1) Straight-through globe valve 2) DC-type globe valve: In the DC or Y-shaped globe valve, the flow path of the valve body is inclined with the main flow channel, so that the flow state is less damaged than the conventional globe valve, so The pressure loss of the valve is also correspondingly small.
3) Angle stop valve: In the angle cut-off valve, the fluid only needs to change in one direction, so that the pressure drop through the valve is smaller than that of the conventional structure.
American standard bellows stop valve ZDAJ41W type 4) Plunger type stop valve: This type of stop valve is a variant of the conventional stop valve. In this valve, the flap and seat are usually designed based on the principle of the plunger. The valve flap is polished into a plunger that is coupled to the valve stem, and the seal is achieved by two elastomeric sealing rings that are placed over the plunger. The two elastomeric seals are separated by a collar and the seal around the plunger is pressed by the load exerted by the bonnet nut on the bonnet. The elastomeric seal can be replaced and can be made from a wide variety of materials. The valve is mainly used for "opening" or "off", but with a special form of plunger or special collar, it can also be used to regulate flow. . Position of the thread on the stem 1) Upper threaded stem stop valve: The thread of the shutoff valve stem is outside the valve body. The advantage is that the valve stem is not eroded by the medium and is easy to lubricate, and such a structure is relatively common.
2) Lower threaded stem stop valve: The thread of the shutoff valve stem is inside the valve body. This type of stem thread is in direct contact with the media and is susceptible to erosion and lubrication. This structure is used in places with small calibers and low temperatures.
There are many manufacturers of shut-off valves in China, and the connection sizes are mostly not uniform. Mainly divided into the following major categories:
1) General class based on JB/T2203-1999 "Structural length of shut-off valve". At present, most domestic safety valve manufacturers are designed and produced according to this standard. Such as Hailai Le Valve Co., Ltd., Zhejiang Luofu Boiler Accessories Factory, Hangzhou Stop Valve Factory, Shanghai Liangzhong Valve Co., Ltd., Shanghai Cut-off Valve Factory, Kaifeng High Pressure Globe Valve Factory, Hai'an Globe Valve Factory, etc. However, this standard is not perfect, the specifications are not complete, single gate stop valve zui large nominal diameter is DN1200, double gate cut-off valve zui large nominal diameter DN1500. According to the specifications of the shut-off valve produced by the factory and the information obtained, the nominal diameter of the angle cut-off valve is DN15, and the nominal diameter of the Z-type straight-through stop valve reaches DN2000. According to the research, the connection sizes of various manufacturers are not uniform. For example, the DN150Z straight-through globe valve, Shanghai Liangzhong Valve Factory, Shanghai Globe Valve Factory and Shanghai Yaze Valve Factory are all different. In order to have a uniform standard, the user can exchange the same specifications during the selection and installation. It is recommended that China General Machinery Research Institute revise JB/T2203-1999 "Structure Length of Globe Valve". It is recommended that the design institute and users choose according to the standard, and the manufacturer of the globe valve is designed and manufactured according to the standard.
The organic aqua regia, sulfuric acid, hydrochloric acid, hydrofluoric acid and various uses of fluorine <br> <br> lined shut-off valve in the shut-off valve suitable for -50 ~ 150 ℃ various concentrations, strong acids, strong oxidants, further Suitable for use in various concentrations of strong alkali organic solvents and other corrosive gases, liquid media.
API American standard cut-off valve American standard cut-off valve performs ANSI and API standards. The sealing surface of the valve disc and seat is made of Slite cobalt-based hard alloy with different hardness. The seal is reliable, high hardness and resistant. Grinding, high temperature resistance, corrosion resistance, good scratch resistance and long life.
The national standard stop valve is the commonly used product of the cut-off valve series. The sealing surface of the valve seat and the valve disc is made of Slite cobalt-based hard alloy with different hardness. The seal is reliable and the hardness is high. Wear resistance, high temperature resistance, corrosion resistance, good scratch resistance and long life.
Needle-type valve needle valve is a small-diameter 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, oil field special series and American standard series.
Low temperature shut-off valves Low temperature shut-off valves are generally referred to as valves operating at temperatures below -110 ° C and are widely used in liquefied natural gas, liquefied petroleum gas and other cryogenic industries. At present, it is possible to manufacture a shut-off valve with a temperature of -196 ° C. All parts are treated with liquid nitrogen for low temperature pretreatment, completely avoiding sealing deformation and leakage during use.
The plunger valve plunger valve, also known as the plunger stop valve, has a sealing surface with a radial sealing structure, and two elastic sealing rings sleeved on the polishing plunger are applied to the valve cover through the connecting bolts of the valve body and the valve cover. The load presses the elastomeric seal around the plunger to seal the shutoff valve.
<br> <br> insulation jacket insulation jacket cut valve globe valve design insulation jacket, external heat source in the external circulation of the valve, the medium can be effectively prevented when the temperature loss through the valve, to ensure the temperature of the medium.
<br> <br> forged steel forged steel cut-off valve shut-off valve in accordance with design and manufacturing standards API602, a valve cover design provides three forms: bonnet bolted, welded valve cover, a pressure tight seal from the valve cover, the user can choose according to need Different forms, RF flange, NPT thread, SW welding type are available.
For oxygen shut-off valve for oxygen shut-off valve <br> <br> use of fine silicon material cast from brass or stainless steel, having high mechanical strength, wear resistance, and good safety. Used in the oxygen pipeline, it has excellent explosion-proof flame retardant performance, eliminating the unsafe factors on the oxygen pipeline, and is widely used in the pipe network of oxygen, steel, metallurgy, petrochemical, chemical and other oxygen projects. In addition to the function of ordinary valves, it has its own characteristics. Strict oil-free measures are taken during manufacturing and all parts are strictly degreased prior to installation.
<br> <br> bellows valve bellows valve formed using stainless steel bellows design, the bellows Test reciprocating 10,000 times without failure, a reliable sealing performance for explosive, toxic and hazardous industrial medium can be effectively Prevent leakage of the valve.
Advantages 1. Simple structure, convenient manufacturing and maintenance.
2. The working stroke is small and the opening and closing time is short.
3, good sealing, small friction between sealing surfaces, long life.
4. The structure of the shut-off valve body is straight-through, direct-flow and right-angle. Straight-through is a common structure of Zui, but its fluid resistance is large. DC fluid resistance is small, and it is mostly used for fluids containing solid particles or high viscosity. The right angle valve body is mostly forged, suitable for small through, high pressure shut-off valves.
5. The frictional force of the sealing surface is smaller and more wear-resistant than the gate valve during the opening and closing process.
6, usually only one sealing surface, good manufacturing process, easy to repair. Disadvantages 1. The fluid resistance is large, and the force required for opening and closing is large.
2. It is not suitable for media with particles, high viscosity and easy coking.
3. The adjustment performance is poor.
4. The type of shut-off valve is divided into external thread type and internal thread type according to the position of the stem thread. According to the flow direction of the medium, there are straight-through, direct-current and angular. The shut-off valve is divided into seals, with a packing seal shut-off valve and a bellows seal shut-off valve.
5. The bellows seal stop valve adopts the design of the bellows seal, completely eliminating the shortcomings of the normal valve stem packing seal aging and easy to leak, not only improving the energy efficiency, increasing the safety of the production equipment, reducing the maintenance cost and frequent Maintenance and maintenance also provides a clean and safe working environment.
Advantages of use 1. Double seal design (corrugated pipe + packing) If the bellows fails, the stem packing will also be avoided;
2, external leakage, and in line with international sealing standards;
3. No fluid loss, reduce energy loss, and improve plant equipment safety;
4, long service life, reduce the number of maintenance, reduce operating costs;
5, rugged bellows seal design, to ensure zero leakage of the valve stem, providing maintenance-free conditions.
The type of the shut-off valve is divided into an external thread type and an internal thread type according to the position of the stem thread. According to the flow direction of the medium, there are straight-through, direct-current and angular. The shut-off valve is divided into seals, with a packing seal shut-off valve and a bellows seal shut-off valve.
The structural form of the stop valve:
The structure of the shut-off valve body is straight-through, direct-flow and right-angle. Straight-through is a common structure of Zui, but its fluid resistance is large. DC fluid resistance is small, and it is mostly used for fluids containing solid particles or high viscosity. The right angle valve body is mostly forged, suitable for small through, high pressure shut-off valves.
The following items should be noted for the installation and maintenance of the shut-off valve:
1. The handwheel and handle operated shut-off valve can be installed at any position of the pipeline.
2. Handwheels, handles and aerodynamic mechanisms are not allowed to be used for lifting.
3. The flow direction of the medium should be consistent with the direction of the arrow shown in the valve body.
The main criteria for the globe valve:
1. GB/T12233-2006 "Universal Valve Iron Globe Valve and Lifting Check Valve"
2, GB/T12235-2007 "Universal valve flange connection steel shut-off valve and lift check valve"
3, JB/T53174-94 "cut-off valve product quality classification"
4. JB/T53165-92 "High Pressure Balance Globe Valve"
5, GB/T587-2008 "Marine flanged valve for marine flanges"
6, GB/T590-2008 "Marine flanged cast iron globe valve"
7, GB/T8464-2008 "iron and copper threaded connection valve"
8, GB8465.2-87 "internal thread connection gate valve, globe valve, ball valve, check valve basic size iron shut-off valve"
1. GB/T12233-2006 "General-purpose valve iron globe valve and lift check valve" 2. GB/T12235-2007 "Universal valve flange connection steel globe valve and lift check valve" 3. JB/T53174- 94 "cut-off valve product quality classification" 4, JB/T53165-92 "high pressure balance cut-off valve" 5, GB/T587-2008 "marine flange flanged valve" 6, GB/T590-2008 "Marine flange cast iron cut-off Valve"7, GB/T8464-2008 "iron and copper threaded connection valve" 8, GB8465.2-87 "internal thread connection gate valve, globe valve, ball valve, check valve basic size iron shut-off valve" cut-off valve related A knowledge stop valve is a valve that moves a closure (valve) along the centerline of the seat. Depending on the form of movement of the flap, the change in the seat opening is proportional to the flap travel. Due to the relatively short opening or closing stroke of the valve stem of this type of valve, and the very reliable cutting function, and because the change of the valve seat opening is proportional to the stroke of the valve flap, it is very suitable for the adjustment of the flow rate. Therefore, this type of valve is well suited for use as a cut or adjustment and throttling. The selection principle is as follows: 1. The shut-off valve should be used on the pipeline or device of high temperature and high pressure medium. Such as thermal power plants, nuclear power plants, high-temperature, high-pressure pipelines of petrochemical systems. 2. On the pipeline where the flow resistance is not strict on the pipeline. That is, the place where the pressure loss is not considered. 3. Small valves can be used with needle valves, instrument valves, sampling valves, pressure gauge valves, etc. 4, there are flow regulation or pressure regulation, but the adjustment accuracy is not high, and the pipeline diameter is relatively small, such as the nominal diameter of ≤ 50mm pipeline, should be used. 5. For small chemical fertilizers and large chemical fertilizers in synthetic industrial production, high-pressure angle shut-off valves or high-pressure angle throttle valves with nominal pressure PN160 nominal pressure 16MPa or PN320 nominal pressure 32MPa should be used. 6. In the desiliconization workshop and the easy coking pipeline in the production of alumina Bayer method, it is easy to select the DC type shut-off valve or the DC type throttle valve with the valve body separated, the valve seat can be removed, and the carbide seal pair. 7. In the water supply and heating projects in urban construction, it is known to pass through smaller pipelines, and the cut-off, balance valve or plunger valve can be used, such as the pipeline passing the nominal less than 150mm. The obvious advantage of zui is that during the opening and closing process, the friction between the valve flap 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 and therefore much smaller than the gate valve. Usually there is only one sealing surface on the valve body and the valve flap, so the manufacturing process is better and easy to repair. Nominal pressure or pressure level: PN1.0-16.0MPa, ANSICLASS150-900, JIS10-20K nominal diameter or caliber: DN10～500, NPS1/2～36" Connection: flange, butt welding, thread, etc. -196°C～700°C Driving mode: pneumatic, electric, hydraulic, gas-liquid linkage, valve body materials: WCB, ZG1Cr18Ni9Ti, ZG1Cr18Ni12Mo2Ti, CF8(304), CF3(304L), CF8M(316), CF3M(316L) , Ti. Choose different materials, which can be applied to water, steam, oil, nitrate, acetic acid, oxidizing medium, urea and other media.
For the shut-off valve, not only will it be installed and maintained, but it will also operate.
To open and close the shut-off valve, the force should be stable and not impact. Some components of the high pressure shut-off valve that have been opened and closed have been considered such that the impact force is not equivalent to a general globe valve.
When the shut-off valve is fully open, the handwheel should be reversed a little to make the threads tightly tight to avoid loose damage.
When the pipeline is used initially, there is a lot of internal dirt. The shut-off valve can be slightly opened, and the high-speed flow of the medium is used to wash it away, and then it is gently closed (cannot be closed quickly and violently closed to prevent residual impurities from pinching the sealing surface) , turn it on again, repeat this many times, flush the dirt, and put it into normal work.
Normally open the shut-off valve, the sealing surface may be stuck with dirt, and when it is closed, it should be washed clean by the above method, and then officially closed.
If the handwheel or handle is damaged or lost, it should be immediately equipped. It should not be replaced by a live wrench, so as not to damage the valve stem, and the opening and closing is not working, resulting in an accident in production.
Some media, after the shut-off valve is closed, cool, so that the valve member shrinks, the operator should close again at the appropriate time, so that the sealing surface does not leave a slit, otherwise the medium flows through the slit at high speed, it is easy to erode the seal. surface.
When operating, if you find that the operation is too laborious, you should analyze the cause. If the packing is too tight, it can be properly relaxed. If the valve stem is skewed, the person should be notified to repair it. In some closed valves, the closing member is heated and expanded, which makes opening difficult; if it must be opened at this time, the bonnet thread can be loosened half a turn to one turn, the stem stress is eliminated, and then the hand wheel is driven.
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