Tag Archive for: globe valve manufacturer

Posts

Electric globe valve selection and application

Electric shut-off valve selection, Electric shut-off valve application, globe valve also named shut off valve or cut off valve.
Advantages of electric shut-off valve:
Once the electric shut-off valve is in the open state, there is no contact between its valve seat and the sealing surface of the disc, so its sealing surface is less mechanically worn, because most of the electric shut-off valves have relatively easy repairs. Or there is no need to remove the entire valve from the pipeline when replacing the sealing

electric globe valve

electric globe valve

element,which is very suitable for the occasion where the valve and the pipeline are welded together. The most obvious advantage is that during the opening and closing process, the friction between the 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 valve seat passage, so it is 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 it is easy to maintain. The flow direction of the medium through this type of valve has changed, so the flow resistance of the electric shut-off valve is higher than that of other valves.

Selection of electric shut-off valve:
Commonly used electric globe valves are electric straight-through globe valves, electric throttle valves, electric angle globe valves, electric DC globe valves, electric plunger globe valves, etc. In addition to electric throttle valves, other electric globe valves generally do not Make high-pressure choices.
1. Angle type electric shut-off valve; in the angle type electric shut-off valve, the fluid only needs to change its direction once, so that the pressure drop through this valve is smaller than that of the conventional structure of the electric shut-off valve.
2. DC type electric shut-off valve; electric shut-off valve in the DC type or Y-shaped electric shut-off valve, the flow passage of the valve body is in a diagonal line with the main flow path, so that the degree of damage to the flow state is smaller than that of the conventional electric shut-off valve, so it passes The pressure loss of the valve is correspondingly small.
3. Plunger type electric shut-off valve: This type of electric shut-off valve is a modification of the conventional electric shut-off valve. In this valve, the disc and valve seat are usually designed based on the plunger principle. The valve clack is polished so that the plunger and the valve stem are connected, and the sealing is achieved by two elastic sealing rings sleeved on the plunger. The two elastic sealing rings are separated by a sleeve ring, and the sealing ring around the plunger is pressed firmly by the load exerted on the bonnet by the bonnet nut.
Electric shut-off valve application:
If the electric shut-off valve is used in high-pressure occasions, it is generally connected by butt welding, or electric angle type shut-off valve is used. According to the material, you can choose carbon steel or 304 stainless steel. If the temperature is relatively high, you need to choose chromium-molybdenum steel or chromium-molybdenum-vanadium steel. The typical J941Y-170V electric high temperature and high pressure stop valve used in power plants.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Related news /knowledge:
Classification of the globe valves-(1);
The working principle and characteristics of the globe valve;
Electric globe valve model coding method.
working principle of electric globe valve

Globe valve structures and design standard

Globe valve structure, Globe valve design standard
The shut-off valve is a particularly common shut-off valve, which is mainly used to connect or cut off the medium in the pipeline, and is generally not used to adjust the flow. The globe valve is suitable for a wide range of pressure and temperature, but it is generally used for medium and small diameter pipelines.

Globe valve (2)

Globe valve (2)

Globe valve (1)

Globe valve (1)

Globe valve (9)

Globe valve (9)

Structural principle of globe valve:
1. The center of the inlet and outlet of the shut-off valve are on the same straight line, and the fluid flows like an S-shaped sphere, so it is also called a spherical shut-off valve.
2. When the valve seat of the valve stem descends toward the bottom sealing surface and is pressed down, the medium stops flowing; when the valve stem rises, the medium passes through the flow path from below to above.
Globe valves generally have direction requirements during installation. The flow direction of the medium in the pipeline generally flows from bottom to top through the valve seat port, which is what we often call the so-called “low inlet and high outlet”. The purpose of this is to reduce fluid resistance and save effort in opening. In the closed state, the valve stem and the packing culvert are not in contact with the medium to ensure that the valve stem and the packing culvert are not damaged or leaked.

Globe valve structure diagram Globe valve structure and design standards:

name Globe valve structure Globe valve design standard
Typical Forged Steel Globe Valve 1. Flow channel JB/T 7746-1995: Shrinkage hole BS5352-1999: Through hole or shrinkage hole (CL150~800); Through hole (Cl1500) JPI-7S-36-1999: Through hole
2. Valve body and bonnet Connection: flange, thread or welding
3. Connection end JB/T 7746-1995: internal thread, socket welding or flange BS5362-1999: internal thread, socket, flange and butt welding JPI-7S-36- 1999: Internal thread, socket
JB/T 7746-1995
BS 5352-1999
JPI-7S-36-1999
Internal pressure self-sealing forged steel globe valve 1. Flow path: shrinkage hole
2. Connection between valve body and bonnet: internal pressure self-sealing
3. Connection end: butt welding, flange or socket
ASME B16.34-1996
Cast steel globe valve 1. Flow path: angle type, straight-through, direct current (Y type)
2. Connection between valve body and bonnet: flange
3. Connection end: flange or butt welding
4. Various types of discs can be used, Usually exposed rod, there are also a few smaller diameter valves with dark rod
JPI-7S-46-1999
JIS B2071-1999
JIS B2072-1999
JIS B2081-1999
JIS B2082-1999
BS 1873-1999
MSS-SP-42-1999
GB/T 12235-1989
BS 5160-1989
Bellows Sealed Globe Valve 1. Flow path: angle type, straight-through, direct current (Y type)
2. Connection between valve body and bonnet: flange
3. Connection end: flange or butt welding
4. Various types of discs can be used, It is usually an exposed stem, but there are also a few valves with smaller diameters that use double stem seals with concealed stem 5, bellows and packing
ASME B16.34-1996
Angle type high pressure globe valve 1. Flow path: angle type
2. Connection between valve body and bonnet: thread, clamp or welding
3. Various types of discs can be used. For ultra-high pressure valves, internal pressure self-balancing discs are usually used
4. The valve body can adopt integral type, two-piece type
5. Connection end: flange or butt welding
ASME B16.34-1996
GB/T 12235-1989
Lining stop valve 1. Flow channel: angle type, straight-through, direct current (Y type)
2. Connection between valve body and bonnet: flange
3. Connection end: flange or butt welding
4. Lining material is rubber, plastic, etc.
ASME B16.34-1996
Two-way three-way globe valve 1. Flow path: two-way three-way flow path
2. Connection between valve body and bonnet: flange
3. Connection end: flange or butt welding
ASME B16.34-1996
Cast steel discharge stop valve 1. Flow path: straight-through
2. Connecting end: flange
3. Disc: upward or downward expansion
4. Connection between valve body and bonnet: flange
ASME B16.34-1996
Three-way globe valve 1. Flow path: Tee
2. Connecting end: Flange
3. Disc: Plane seal
ASME B16.34-1996
Pressure gauge shut-off valve 1. Flow path: DC, right angle, three-way
2. Connection between valve body and bonnet: integral forging or thread
3. Connection end: external thread, clamp
4. Disc: Cone and flat
ASME B16.34-1996
Water seal stop valve 1. Flow path: DC
2. Connection end: socket welding, butt welding
3. Valve body and bonnet: both forged, with a chromium nickel steel or carbon steel
4. Disc: Cone seal (DN10~25mm) , Plane seal (DN32~200mm)
E101-1999
GB/T 12235-1999
ASME B16.34-1996
Slurry shut-off valve 1. Flow path: DC
2. Connection end: Flange
3. Valve body structure: The valve seat is clamped between the left and right valve bodies, and the left and right valve bodies are connected by bolts.
4. The valve body and the bracket are connected by bolts.
5. The valve cover: CL150 is forged as a whole, CL300 and CL400 are split type, using strut connection.
6. Disc: Cone surface is sealed into plane seal, or throttle type sealing surface is overlaid with hard alloy
GB/T 12235-1989
ASME B16.34-1996
Angle globe valve 1. Flow path: right angle
2. Connection end: flange
3. Valve body and bonnet: forged throttling type. The sleeve is drilled and the piston moves up and down in the sleeve to adjust the flow.
4. Valve body, valve Cover connection: bolt connection
API 6A-2002
Titanium Globe Valve 1. Flow path: straight-through
2. Valve body, bonnet, stuffing box, valve clack, valve stem are made of titanium
3. Valve body and bonnet connection: bolt connection
4. Valve clack is flat seal
GB/T 12235-1989

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

related news /knowledge:
The structure and connection of the American standard valve;
Classification of the globe valves-(2);
The working principle and characteristics of the globe valve;
Pneumatic globe valve model preparation method

bellows globe valve vs ordinary globe valve

The difference and comparison between bellows globe valve and ordinary globe valve
The bellows globe valve is also called the bellows seal globe valve. Through automatic seam welding, a metal barrier is formed between the fluid medium and the atmosphere to ensure the design of zero leakage of the valve stem. Compared with traditional globe valves, it has the following advantages:

Globe valve (9)

Globe valve (9)

1. The bellows globe valve has a long service life, reduces the number of maintenance and lowers operating costs. The sturdy and durable bellows seal design ensures zero leakage of the valve stem and provides maintenance-free conditions.
2. The valve opening and closing torque is small, reducing labor intensity, and can drive any form of driving device, which is convenient for remote control.
3. The appearance is beautiful, the valve channel has a smooth streamline, and the flow resistance coefficient of the valve is reduced. It is a high-quality energy-saving product.
4. The outer seal of the valve adopts bellows seal and graphite, stainless steel gasket seal, the seal is reliable, and the sealing packing does not need to be replaced for long-term use. In industrial use, the leakage caused by the stop valve: high temperature, highly toxic, flammable and explosive, radiant medium, etc., not only pollute the environment, but also often cause significant personal and property losses. However, this type of valve is much safer and more stable, and strictly adopts foreign advanced standards in design and manufacturing.

Advantages and application of bellows globe valve The bellows globe valve has no leakage, and it is safer to be used in high-risk media. Ordinary globe valve is sealed with packing, the valve stem and packing will slide, and it is easy to leak at low temperature (spool).
The bellows cut-off valve uses a closed bellows that can be stretched and compressed to replace the packing seal, which can effectively prevent external leakage caused by packing loss. It is generally used for the transmission of highly permeable media, such as valves on hydrogen systems, as long as the bellows is not damaged, there is generally no leakage; while the general shut-off valve is sealed with packing, which is prone to leakage.
The opening or closing stroke of the valve stem of this kind of valve is relatively short, and it has a very reliable cut-off function. Also, because the change of the valve seat port is proportional to the stroke of the valve disc, it is very suitable for flow adjustment. Therefore, this type of valve is very suitable for use as a shut-off or adjustment and throttling.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Related news /knowledge: The structure and characteristics of bellows gate valve; Comparison of bellows globe valve and ordinary globe valve; 

Installation attentions for valves

Precautions for valve installation:

Globe valves, throttle valves, pressure reducing valves, check valves and other valves are all directional. If the throttle valve is installed upside down, it will affect the use effect and life. If the pressure reducing valve does not work at all, if it is stopped The return valve can even cause danger.

lift-swing-check-valve-2

lift-swing-check-valve-2

Generally, the valve has a direction mark on the valve body; if not, it should be correctly identified according to the working principle of the valve.

The valve cavity of the shut-off valve is asymmetrical left and right, and the fluid must pass through the valve port from bottom to top, so that the fluid resistance is small (determined by the shape), and the opening is labor-saving (due to the upward pressure of the medium), and the medium does not press the packing after closing, which is convenient for maintenance . This is the reason why the globe valve cannot be reversed. Other valves also have their own characteristics.

The valve installation location must be convenient for operation; even if the installation is temporarily difficult, it is necessary to consider the long-term work of the operator.

It is best to keep the valve hand wheel flush with the chest (usually 1.2 meters away from the operating floor), so that opening and closing the valve is easier. The hand wheel of the floor valve should be upward, do not tilt, to avoid

Globe valve (9)

Globe valve (9)

awkward operation. The valve of the wall machine and the equipment should also leave room for the operator to stand. It is necessary to avoid operating from the sky, especially acid and alkali, toxic media, etc., otherwise it is very unsafe.

Do not install the gate valve upside down (that is, the handwheel is down), otherwise the medium will remain in the valve cover space for a long time, which will easily corrode the valve stem, and it is taboo for certain process requirements. At the same time, it is extremely inconvenient to replace the packing.

1. The pressure reducing valve should be installed upright on the horizontal pipeline, and not inclined in all directions.

2. As for the lift check valve, make sure its valve flap is vertical when installing it so that it can be lifted flexibly.

3. Swing check valve, ensure that its pin shaft is level when installing, so that it can swing flexibly.

4. Do not install the rising stem gate valve underground, otherwise the exposed stem will be corroded due to moisture.

Tianjin Tanghai Valve Manufacturing Co., Ltd. is one of the largest butterfly valve manufacturers in China, main products are butterfly valves, check valves, gate valve and globe valves. Key words:  butterfly valve, lug type butterfly valve, wafer type butterfly valve, U-type butterfly valve, double flange butterfly valve, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…)

Electric globe valves’ structural features and installation attention

Structural features of electric globe valve:

1. Open and close without friction. This function completely solves the problem of traditional valves affecting the

Globe valve (6)

Globe valve (6)

sealing due to mutual friction between the sealing surfaces.

2. Top-mounted structure. The valves installed on the pipeline can be directly inspected and repaired online, which can effectively reduce device shutdown and reduce costs.

3. Single valve seat design. Eliminates the problem that the medium in the valve cavity affects the safety of use due to abnormal pressure increase.

4. Low torque design. The valve stem with special structure design can be opened and closed easily with only a small handle.

5. Wedge-shaped sealing structure. The valve relies on the mechanical force provided by the valve stem to press the ball wedge onto the valve seat to seal, so that the sealing performance of the valve is not affected by changes in pipeline pressure, and the sealing performance is reliably guaranteed under various working conditions.

6. Self-cleaning structure of the sealing surface. When the ball is tilted away from the valve seat, the fluid in the pipeline passes through the sealing surface of the ball evenly at 360°, which not only eliminates the local erosion of the valve seat by the high-speed fluid, but also washes away the accumulation on the sealing surface to achieve the purpose of self-cleaning .

7. The valve body and bonnet with valve diameter below DN50 are die forgings, and the valve body and bonnet above DN65 are steel castings.

8. The connection forms of the valve body and the bonnet are different, clamp pin shaft connection, flange gasket connection and self-sealing thread connection.

9. The sealing surfaces of the valve seat and the valve disc are all made of plasma spray welding or surfacing welding of cobalt-chromium-tungsten cemented carbide. The sealing surface has high hardness, wear resistance, scratch resistance and long service life.

10. The valve stem material is nitrided steel. After nitriding, the surface of the stem has high hardness, wear resistance, scratch resistance, corrosion resistance and long service life.

Electric shut-off valve installation attention:

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. The valve can be installed at any position of the pipeline, and at the same time, choose a carbon steel or alloy steel valve according to the temperature of the medium and the medium.

3. The electric globe valve should be installed vertically as far as possible, with the valve stem upward.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Related news /knowledge:
Installation attentions for valves;
Structural characteristics of butterfly valve
Structural characteristics of metal hard seal butterfly valve;
The structural characteristics and uses of the wafer butterfly valve;

Characteristics and working principle of electric globe valve

Features of electric globe valve:

  • The fluid resistance is small, and its resistance coefficient is equal to that of a pipe section of the same length.

    Globe valve (9)

    Globe valve (9)

  • Simple structure, small size and light weight. Electric globe valve
  • It is tight and reliable. The sealing surface material of the gate valve is widely used plastic, and it has good sealing performance. It has also been widely used in vacuum systems.
  • It is easy to operate and open and close quickly. It only needs to rotate 90° from fully open to fully closed, which is convenient for remote control.
  • The maintenance is convenient, the gate valve has a simple structure, the sealing ring is generally movable, and it is convenient to disassemble and replace.
  • When fully open or fully closed, the sealing surface of the ball and the valve seat is isolated from the medium, and the medium will not cause erosion of the valve sealing surface when the medium passes.
  • It has a wide range of applications, with a diameter ranging from a few millimeters to a few meters, and can be applied from high vacuum to high pressure.

Electric globe valve classification:

According to its channel position, it can be divided into straight-through type and right-angle type.

Working principle of electric globe valve:

The working principle of the electric shut-off valve is to make the valve unblocked or blocked by rotating the valve. The gate valve switch is light, small in size, can be made into a large diameter, reliable in sealing, simple in structure, convenient in maintenance, the sealing surface and the spherical surface are often closed, and it is not easy to be eroded by the medium. It is widely used in various industries.

A. Opening process of globe check valve:

  • In the closed position, the valve body is pressed against the valve seat by the mechanical pressure of the valve stem.
  • When the hand wheel is turned counterclockwise, the valve stem moves in the opposite direction, and the angular plane at the bottom causes the ball to separate from the valve seat.
  • The valve stem continues to lift and interacts with the guide pin in the spiral groove of the valve stem, so that the ball begins to rotate without friction.
  • Until it reaches the fully open position, the valve stem is raised to the limit position, and the ball rotates to the fully open position.

B. Closing process of electric globe valve:

  • When closing, turn the handwheel clockwise, the valve stem begins to drop and the ball leaves the valve seat to start rotating.
  • Continue to rotate the hand wheel, and the valve stem will be acted on by the guide pin embedded in the upper spiral groove to make the valve stem and the gate rotate 90° at the same time.
  • When it is about to close, the gate body has rotated 90° without contact with the valve seat.
  • In the last few turns of the handwheel, the angular plane at the bottom of the valve stem mechanically wedges and presses the sphere to make it tightly press on the valve seat to achieve a complete seal.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Related news/knowledge:
Characteristics of ball valve;
The working principle of butterfly valve (picture);
Electric ball valve principle | Electric ball valve working principle;
Working principle of electric gate valve

Classification of the globe valves-(2)

According to the classification of purposes, the globe valve can be divided into the following types:

12 Globe-valve-4

12 Globe-valve-4

The fluorine-lined stop valve: it is suitable for various concentrations of aqua regia, sulfuric acid, hydrochloric acid, hydrofluoric acid and various organic acids, strong acids, strong oxidants, and various concentrations of strong alkali organic solvents and other Use on corrosive gas and liquid medium pipelines.

The national standard globe valve: it is the most commonly used product in the globe valve series. The API American standard globe valve and the American standard globe valve implement ANSI and API standards. The sealing surfaces of the disc and seat are made of Stellite cobalt-based hard with different hardness. It is made of alloy surfacing, with reliable sealing, high hardness, wear resistance, high temperature resistance, corrosion resistance, good scratch resistance and long life.

Needle valve: it is a small-caliber instrument valve, which plays a role of opening and closing and precise flow control in the instrument measurement pipeline system. It mainly includes power station instrument series, oil field special series, American standard series, etc.

Cryogenic globe valve: it usually refers to the valve whose working temperature is lower than -110℃, which is widely used in LNG, LPG and other low temperature industries. Since 2008, the globe valve with a suitable temperature of -196℃ can be manufactured, and all parts are pretreated with liquid nitrogen at low temperature to completely avoid seal deformation and leakage during use.

The plunger valve: it is also known as the plunger stop valve. Its sealing surface adopts a radial sealing structure. The load exerted on the valve cover by two elastic sealing rings sleeved on the polished plunger through the connecting bolts of the valve body and the valve cover The elastic sealing ring around the plug compresses the shut-off valve for sealing.

The insulation jacket cut-off valve: it adopts the insulation jacket design, using external heat source to circulate heating outside the valve, which can effectively prevent temperature loss when the medium passes through the valve and ensure the temperature of the medium.

The forged steel globe valve: it is designed and manufactured in accordance with API 602 standards, and provides three bonnet design forms: bolted bonnet, welded bonnet, pressure self-tightening bonnet, users can choose different forms according to their needs, providing RF flanges, NPT thread, SW welding type three connection methods.

The special oxygen stop valve: it 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 in oxygen pipelines, it has the best explosion-proof and flame-retardant performance, eliminates the unsafe factors on the oxygen pipelines, and is widely used in the pipeline network of oxygen-using projects such as steel, metallurgy, petrochemical, and chemical industries. In addition to the functions of ordinary valves, it also has its own characteristics. Strict oil prohibition measures are adopted during manufacturing, and all parts are subjected to strict degreasing treatment before installation.

The bellows stop valve: it adopts a shaped stainless steel bellows design. The bellows reciprocating test is 10,000 times without failure, and the sealing performance is reliable. It is suitable for industrial and mining with inflammable, explosive, toxic and harmful media, and can effectively prevent valve leakage.

Tianjin Tanghai Valve Manufacturing Co., Ltd. is one of the largest  valve manufacturers in China, main products are butterfly valves, check valves, gate valve and globe valves. Details: butterfly valve, lug type butterfly valve, wafer type butterfly valve, U-type butterfly valve, double flange butterfly valve, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…)

Classification of the globe valves-(1)

According to the channel direction, the globe valve is devided into 4 types:

Globe valve (6)

Globe valve (6)

1) Straight-through globe valve.
2) Direct flow stop valve: In direct flow or Y-shaped stop valve, the flow passage of the valve body is in a diagonal line with the main flow passage, so that the damage degree of the flow state is less than that of the conventional stop valve, so the pressure loss through the valve is also corresponding Is too small.
3) Angle type stop valve: In the angle type stop valve, the fluid only needs to change its direction once, so that the pressure drop through this valve is smaller than that of the conventional structure.
4) Plunger type globe valve: This type of globe valve is a variation of the conventional globe valve. In this valve, the disc and valve seat are usually designed based on the plunger principle. The valve clack 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 pressed firmly by the load exerted on 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 “open” or “close”, but it is equipped with a special form of plunger or a special collar, which can also be used to adjust the flow .

The position of the thread on the valve stem:

1) Upper threaded stem stop valve: The thread of the stem of the stop valve is on the outside of the valve body. The advantage is that the valve stem is not corroded by the medium and is convenient for lubrication. This structure is more common.

2) Bottom thread stem stop valve: The thread of the stem of the stop valve is in the valve body. The stem thread of this structure is in direct contact with the medium, which is susceptible to corrosion and cannot be lubricated. This structure is used in places with small diameters and low temperatures.

There are many domestic manufacturers of globe valves, and most of the connection sizes are not uniform. It is mainly divided into the following categories: General category based on JB/T2203-1999 “Structural Length of Stop Valves”. At present, most domestic shut-off valve manufacturers design and produce according to this standard. However, this standard is not perfect, and the specifications are not complete. The maximum nominal diameter of a single gate valve is DN1200, and the maximum nominal diameter of a double gate valve is DN1500. According to the specifications of the shut-off valve produced by the manufacturer and the information available, the smallest nominal diameter of the angle-type shut-off valve is DN15, and the nominal diameter of the Z-type straight-through shut-off valve reaches DN2000. After research, the connection size of each manufacturer is not uniform. In order to have a unified standard, users can interchange the same specifications when selecting and installing, it is recommended that China General Machinery Research Institute revise JB/T2203-1999 “Structural Length of Stop Valves”. It is recommended that the design institute and users choose according to the standard, and the stop valve manufacturer should design and manufacture according to the standard.

The working principle and characteristics of the globe valve

The globe valve is a tool that relies on the pressure of the valve stem to make the sealing surface of the disc and the sealing surface of the valve seat tightly fit to prevent the flow of the medium. It is a forced sealing valve and is one of the most widely used valves.

According to the direction of the passage, the globe valve is divided into four types: straight-through globe valve, direct-flow globe valve, angle globe valve and plunger globe valve.
1. Working principle of globe valve:

Globe valve (9)

Globe valve (9)

The stop valve, also called the cut-off valve, is one of the most widely used valves. The reason why it is popular is that the friction between the sealing surfaces is small during the opening and closing process, which is relatively durable, has a small opening height, and is easy to manufacture. , Easy maintenance, not only suitable for medium and low pressure, but also suitable for high pressure. The closing principle of the shut-off valve is to rely on the pressure of the valve stem to make the sealing surface of the disc and the sealing surface of the valve seat closely fit, preventing the flow of the medium. Our country’s valve “Sanhua” once stipulated that the flow direction of the stop valve should be from top to bottom, so there is directionality when installing. The structural length of the shut-off valve is longer than that of the gate valve, and the fluid resistance is large, and the sealing reliability is not strong during long-term operation.

As one of the most important cut-off valves, the globe valve plays an important role in the aerospace field. As an important component of aerospace equipment, the shut-off valve realizes the functions of medium transportation, cut-off, and adjustment, and its sealing performance directly affects the safe and reliable operation of aerospace equipment. Studying the influencing factors and influencing rules of the sealing characteristics of typical globe valves has guiding significance for the structural design of the valve sealing pair, thereby improving the sealing performance and reliability of the valve.

2. Globe valve characteristics:

The valve plays an important role in cutting off and throttling the medium in the pipeline. As an extremely important cut-off valve, the valve is sealed by applying a torque to the valve stem, and the valve stem is in the axial direction. The valve clack applies pressure to make the sealing surface of the valve clack closely fit the sealing surface of the valve seat, and prevent the medium from leaking along the gap between the sealing surfaces.

The sealing pair of the globe valve is composed of a valve flap sealing surface and a valve seat sealing surface, and the valve stem drives the valve flap to move vertically along the center line of the valve seat. During the opening and closing process of the globe valve, the opening height is small, the flow is easy to adjust, and the manufacturing and maintenance are convenient, and the pressure application range is wide.

Compared with another commonly used shut-off valve in industrial production, an alarm valve, the shut-off valve is simpler than the former in terms of structure, and is easy to manufacture and maintain. In terms of service life, the sealing surface of the globe valve is not easy to wear and scratch. During the opening and closing process of the valve, there is no relative sliding between the valve disc and the sealing surface of the seat, so the wear and abrasion of the sealing surface are small, so the sealing is improved. During the full closing process of the auxiliary service life stop valve, the disc stroke is small, and its height is relatively small compared to the alarm valve. The shortcoming 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 body is relatively tortuous, the fluid flow resistance is large, and the fluid power is lost in the pipeline.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Related news/knowledge:
bellows globe valve structure and features;
working principle of electric globe valve;
Electric globe valve selection and application;
Pneumatic globe valve model preparation method