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Design Features of Electric Gate Valve

An electric gate valve is a gate valve that uses an electric actuator to control the opening and closing of the valve. Its structure can be divided into upper and lower parts, the upper part is the electric actuator, and the lower part is the gate valve body. Connect the electric actuator and the gate valve, after installation and debugging, it becomes an electric gate valve. The electric gate valve uses electric energy to realize the opening and closing of the valve, so as to control the interception and circulation of the pipeline medium.

DN1000-DIN-F5-NRS gate valve-IS&Y (6)

DN1000-DIN-F5-NRS gate valve-IS&Y (6)

The switching speed of the electric gate valve can be adjusted, the structure is relatively simple, and the maintenance is easier. Its design structure also has its own characteristics.
1. The electric gate valve adopts pressure self-tightening seal, which has excellent sealing performance and is reliable and safe to use.
2. The electric gate valve adopts a double gate with a universal roof structure in the middle, which can automatically adjust the degree of sealing between the gate and the valve seat to ensure the sealing performance of the valve. At the same time, this structure is very convenient to maintain and save costs.
3. The sealing surface of the gate and the valve seat is made of cobalt-chromium-tungsten cemented carbide by plasma spray welding. The sealing surface has high hardness, and is very wear-resistant and corrosion-resistant, which prolongs the service life of the valve.
4. The valve stem is made of nitrided steel, and the surface is nitrided, which has high hardness, good performance and long life.
5. The electric device of the electric gate valve is equipped with a torque control mechanism, an on-site operating mechanism and a hand and electric switching mechanism. It can also carry out remote operation and intelligent control. It is suitable for use in situations where manual operation is difficult or the pipeline environment is complex and dangerous.
6. When the electric gate valve is used for the first time, during installation and debugging, it is necessary to manually open the valve to about half of the position, so as to avoid the valve or electrical equipment damage due to the reverse connection of the motor phase sequence.

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:
Working principle of electric gate valve
Electric ball valve principle | Electric ball valve working principle
Working principle diagram of electric butterfly valve
Types and selection of electric valves

The Basic Knowledge of Butterfly Valves

Butterfly valve is also called butterfly type valve or flap valve, which is a kind of regulating valve with very simple structure. Its main structure is composed of valve body, butterfly plate, valve stem, valve seat, transmission device and operating mechanism.
How does the butterfly valve work?
The working principle of the butterfly valve is that a disc-shaped butterfly plate is used as the opening and closing part, which is connected with the valve stem and rotates with the valve stem around its own axis in the valve body to realize the opening and closing and adjustment of the pipeline. When the butterfly plate rotates 90° in the closed position, the valve is in a fully open state. At this time, the thickness of the butterfly plate is the only resistance to the flow of the medium, and the resistance is very small. In addition, changing the angle of the butterfly plate can be used to adjust the media flow. Butterfly valves are generally installed in the diameter direction of the pipeline and can be installed at any position.
The structural principle of the butterfly valve is very suitable for making large-diameter valves, which are used in general industries such as petroleum, gas, chemical industry, and water treatment. The most common fault in the use of butterfly valves is that the sealing surface rubber of the butterfly valve is corroded, worn and teared, aging or even falling off during long-term continuous use, which causes the valve to jam and cannot be closed normally, which affects the valve’s performance. Sealing performance. In order to solve this problem, the structure of the butterfly valve has been continuously optimized.
The simplest butterfly valve is the concentric butterfly valve, that is, the shaft center of the valve stem, the center of the butterfly plate, and the center of the body are in the same position. The structure of this kind of butterfly valve is very simple. The disadvantage is that the butterfly plate and the valve seat are severely squeezed and scratched, and the sealing surface wears quickly.
In order to make up for the shortcomings of the concentric butterfly valve, the single eccentric butterfly valve was born. The stem axis of the single eccentric butterfly valve deviated from the sealing center of the valve plate, so that the lower end of the butterfly plate is no longer the center of rotation, and the lower end of the butterfly plate and the valve seat are reduced. The pressure brought by the excessive squeeze.

ductile iron, DI, butterfly valve, manufacturer, center line, TH valve

ductile iron, DI, butterfly valve, manufacturer, center line, TH valvedoes

The double eccentric butterfly valve is an improvement based on the single eccentric butterfly valve. The stem axis of the double eccentric butterfly valve deviates from the center of the seal and the center of the valve body. The advantage of the double eccentric butterfly valve is that the butterfly plate can be quickly separated from the valve seat after the valve is opened, which largely eliminates unnecessary squeezing and scratching between the butterfly plate and the valve seat, and also reduces the opening and closing of the valve. Resistance, wear and tear are reduced, and the life of the valve seat is improved.
All of the above valves have a shortcoming. They are all soft-sealed and cannot withstand high temperatures, but the use of high-temperature resistant metal materials to make butterfly valves has no guarantee of sealing performance. In order to solve this problem, a triple eccentric butterfly valve was developed.
The biggest feature of the triple eccentric butterfly valve is that it fundamentally changes the sealing structure of the butterfly valve. The triple eccentric butterfly valve is a torsion seal, not a position seal, that is to say, it no longer relies on the elastic deformation of the valve seat to seal, but completely relies on The contact surface pressure of the valve seat achieves the sealing effect. Therefore, the triple eccentric butterfly valve is resistant to high temperature, high pressure, and corrosion, but also has a good sealing effect.

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 sealing characteristics and principle of eccentric butterfly valve;
Basic knowledge of valve;
Introduction to basic knowledge of gate valve;
Selection and application of eccentric butterfly valve

Applicable occasions and application conditions of butterfly valves

At present, the butterfly valve has become the most widely used valve in the application field. Many people are not very familiar with the applicable occasions of butterfly valves. This article will take you to understand the applicable occasions and application conditions of butterfly valves, so that you have a better understanding of butterfly valves.
When the valve plate of the butterfly valve is opened and closed, there is wiping property between the butterfly plate and the valve seat, so the butterfly valve can be used in the flowing medium pipeline with suspended solid particles, according to the strength of the seal. It can also be used in powder and granular flowing medium pipelines.

U-type-flange-butterfly-valve-2

U-type-flange-butterfly-valve-2

The structure length and overall height of the butterfly valve are not large, and the opening and closing speed is very fast. When the butterfly valve is fully opened, only the butterfly plate in the valve body is the only resistance to the flow of the medium, so the fluid resistance of the butterfly valve is also very small. Between 15° and 70°, sensitive flow control can be performed. Therefore, according to the structure principle of the butterfly valve, the butterfly valve is most suitable for making large-diameter valves.

Specifically, the application occasions of butterfly valves are as follows:
1. In the pipeline that requires throttling, adjustment and control of flow;
2. In the working environment of mud medium and medium containing solid particles;
3. In occasions requiring short valve structure length;
4. In occasions requiring fast opening and closing speed;
5. In occasions where the pressure difference is small.

The butterfly valve can also be used under the following conditions:
1. In the case of two-position adjustment, narrowing passage, low noise, cavitation and vaporization, a small amount of leakage to the atmosphere, and abrasive media, butterfly valves can be used.
2. Under special working conditions, throttling adjustment or strict sealing requirements, or severe abrasion, low temperature and other working conditions require the use of three-eccentric or double-eccentric special butterfly valves with metal sealing belts.

The above is an introduction to the applicable occasions and application conditions of the butterfly valve. I hope to provide you with help in the use of the butterfly valve. Tanghai Valve is a high-quality butterfly valve manufacturer. If you have a need for butterfly valves, look for the brand of Tanghai Valve.

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:
Applicable occasions and operation method of ball valve;
Applicable occasions of butterfly valve;
Valve material and valve standards-(8)- Monel alloy application;
The main classification and use conditions of valve sealing materials

What is butt welding? (1)

Butt resistance welding (hereinafter referred to as butt welding) is a type of resistance welding method that uses resistance heat to weld two workpieces along the entire end surface at the same time. Butt welding has high

welding

welding

productivity and easy automation, so it is widely used.
Application of butt welding:
Butt welding has high productivity and easy automation, so it is widely used. Its application range can be summarized as follows:
(1) The length of the work piece, such as the butt welding of strip steel, profile, wire, steel bar, rail, boiler steel pipe, oil and natural gas transportation pipeline.
(2) Butt welding of annular workpieces, such as car rims and bicycles, motorcycle rims, butt welding of various chain links, etc.
(3) Assembling welding of components The simple rolling, forging, stamping or machining parts are butt-welded into complex parts to reduce costs. For example, butt welding of automobile steering shaft shell and rear axle housing, butt welding of various connecting rods and tie rods, and butt welding of special parts.
(4) Butt welding of dissimilar metals can save precious metals and improve product performance. For example, the butt welding of the working part of the tool (high-speed steel) and the tail (medium carbon steel), the butt welding of the head (heat-resistant steel) and the tail (structural steel) of the exhaust valve of an internal combustion engine, the butt welding of aluminum and copper conductive joints, etc. .
Classification of butt welding:
Butt welding is divided into resistance butt welding and flash butt welding.
Resistance butt welding
Resistance butt welding is a method in which the end faces of the two workpieces are always pressed tightly, heated to a plastic state by resistance heat, and then upset pressure is quickly applied (or no upset pressure is applied and only the pressure during welding is maintained) to complete the welding.
One, resistance and heating of resistance butt welding
The resistance distribution during butt welding is shown in the figure. The total resistance can be expressed by the following formula:
R=2Rω+RC+2Reω
where Rω-the internal resistance of the conductive part of a workpiece (Ω);
Rc–the contact resistance between two workpieces (Ω);
Rω–The contact resistance between the workpiece and the electrode (Ω);
The contact resistance between the workpiece and the electrode is usually ignored due to its small resistance and far from the joint surface.
The internal resistance of the workpiece is proportional to the resistivity ρ of the welded metal and the length l0 of the workpiece extending from the electrode, and inversely proportional to the cross-sectional area s of the workpiece.
Same as spot welding, the contact resistance of resistance butt welding depends on the surface condition, temperature and pressure of the contact surface. When the contact resistance has obvious oxides or other stolen goods, the contact resistance is large. The increase in temperature or pressure will reduce the contact resistance due to the increase in the actual contact area. At the beginning of welding, the current density at the contact point is very large; after the end surface temperature rises rapidly, the contact resistance decreases sharply. When heated to a certain temperature (steel 600 degrees, aluminum alloy 350 degrees), the contact resistance disappears completely.
Like spot welding, the heat source during butt welding is also the resistance heat generated by the resistance of the welding zone. In resistance butt welding, the contact resistance exists for a very short time, and the heat generated is less than 10-15% of the total heat. But because this part of the heat is generated in a very narrow area near the contact surface. Therefore, the temperature in this area will increase rapidly, and the internal resistance will increase rapidly. Even if the contact resistance disappears completely, the heat generation intensity in this area is still higher than other places.
The harder the welding rod used (that is, the larger the current and the shorter the energization time), the smaller the pressing force of the workpiece, and the more obvious the influence of contact resistance on heating.

Valve flow characteristic curve and classification

The flow characteristic of the valve is the relationship between the relative flow of the medium flowing through the regulating valve and its opening under the condition that the pressure difference between the two ends of the valve remains constant. Flow characteristic is an important technical index and parameter of regulating valve. It is very important to make the correct selection in the application process of the control valve.

Flow characteristics of regulating valve

Flow characteristics of regulating valve

Valve flow characteristics can be defined as: the relative flow of the controlled medium flowing through the valve, and the relationship between the relative opening (relative displacement) of the valve is called the flow characteristics of the regulating valve. Generally speaking, it is divided into four types: straight line, equal percentage (logarithm), parabola and quick opening! The specific description and advantages are as follows:

1. The linear characteristic refers to the linear relationship between the relative flow of the valve and the relative opening, that is, the time constant of the flow change caused by the change of unit opening. The relative stroke of the linear characteristic is linear with the relative flow. The flow change caused by the change of unit stroke is constant. When the flow is large, the relative value of the flow changes little, and when the flow is small, the relative value of the flow changes greatly.

2. the equal percentage characteristic (logarithm) means that the relative flow change caused by the change of the unit opening is proportional to the relative flow at that point, that is, the amplification factor of the regulating valve changes, and it increases with the increase of the relative flow. The relative stroke and relative flow of equal percentage characteristics are not in a linear relationship. The change in flow caused by the change of unit stroke at each point of the stroke is proportional to the flow at this point, and the percentage of flow change is equal. Therefore, its advantage is that when the flow rate is small, the flow rate changes small, and when the flow rate is large, the flow rate changes greatly, that is, it has the same adjustment accuracy at different opening degrees.

3. the parabolic characteristic means that the relative flow change caused by the change of the relative opening of the unit is proportional to the square root of the relative flow value at this point. The flow rate changes in proportion to the two sides of the stroke, and generally has an intermediate characteristic between linear and equal percentage characteristics.

4. the quick opening flow characteristic means that there is a larger flow when the opening is small. With the increase of the opening, the flow can reach the maximum quickly, and then the opening is increased, and the flow change is small, so it is called For quick opening characteristics.

The flow characteristic of the diaphragm valve is close to the quick opening characteristic, the flow characteristic of the butterfly valve is close to the equal percentage characteristic, the flow characteristic of the gate valve is the linear characteristic, the flow characteristic of the ball valve is linear in the middle opening and closing stage, and the equal percentage characteristic in the middle opening.

Globe valve (9)

Globe valve (9)

Under normal circumstances, ball valves and butterfly valves are usually not used for adjustment. If they are used for adjustment, they are only used for adjustment when the opening is small. Generally, they can be classified as quick-opening, and they are really used for adjustment. Most of them are basically cut-off valves (globe valve). The valve head is processed into a parabolic cone, spherical shape, etc., and different curve characteristics are used. Generally speaking, as an adjustment, the basic percentage characteristic is used more.

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:
Comparison table of valve diameter and medium flow rate;
Working principle and movement mode of gate valve;
Valve actuator / actuation -(4)-angle stroke valve actuator application;
Application of low temperature butterfly valve

Valve material and valve standards-(7)- Monel alloy

Monel alloy for corrosion resistant valve
1. Introduction/overview of Monel alloy:
Monel alloy, cast nickel alloy, Hastelloy alloy, etc. are all materials for making special purpose valves. Monel alloy is a Ni-Cu alloy in nickel-based corrosion-resistant alloys. It was first developed by the US Nickel Company. Its typical composition is 70% Ni and 30% Cu. It is the most widely used nickel-based corrosion-resistant alloy.

Monel alloy not only has high strength and toughness, but also has excellent resistance to corrosion by reducing acid and strong alkali media and sea water, so it is usually used to manufacture and transport hydrofluoric acid (HF), salt water, neutral media, and alkali salts. And reducing acid medium equipment. Monel alloy is also suitable for dry chlorine, hydrogen chloride, high temperature chlorine (425°C) and high temperature hydrogen chloride and other media, but it is not resistant to corrosion by sulfur-containing media and oxidizing media (such as nitric acid, media with high oxygen content), and it is nickel It reacts violently with sulfur and oxygen and easily forms Ni3S2 and NiO.

2. Performance of Monel alloy:
Monel alloy is a Ni-Cu solid solution, where Cu is used as a non-oxidizing resist added to Ni, which improves the corrosion resistance of nickel alloys and acts as a strengthening alloy. The addition of C can improve the casting performance of the alloy, but only 0.15% of C can be dissolved in the alloy at room temperature, and the excess C will be precipitated as a graphite phase. Adding 1.5%-3.5% Fe can also improve the casting performance of the alloy. Adding Mn and Si can improve the mechanical properties of the alloy, especially the content of Si has an important influence on the mechanical and physical properties of the Monel alloy.

3. Classification of Monel alloy:
Monel alloys are classified into casting alloys and deformed alloys.
3.1 Deformation alloy: There are more than 10 types of deformed Monel alloys in the United States, such as Monel400, MonelC, Monel403, Monel404, Monel R2405, Monel406, Monel411, MonelK500, MonelK501 and Monel502. Because Monel has its own representation methods in different American standard systems, SAE and ASTM jointly developed ASTM2SAE unified digital system (unified numbt system2 UNS) in order to facilitate the use and unified management of calculations. In the United States’ UNS, nickel alloys have 5 grades of deformed Monel alloys, including solid solution hardened No5500 (Monel400), No4404 (Monel404) and No4405 (MonelR2405), and precipitation hardened NO5500 (MonelK500) and NO5502 (Monel502). ) Etc. (refer to Table 1). Among them, the deformed Monel alloy commonly used in the manufacture of corrosion-resistant valves is Monel400 and MonelK500.
Table 1. Chemical composition of deformed Monel alloy in United States UNS

Grade name chemical composition/ %
C Si Mn S Ni Fe others
NO4400(Monel400) ≤0.3 ≤0.5 2 ≤0.024 63-70 ≤2.5 Cu base
No4404(Monel404) ≤0.15 ≤0.1 ≤0.1 ≤0.024 52-57 ≤0.5 Cu base, Al≤0.05
No4405(MonelR2405) ≤0.3 ≤0.5 ≤2.0 0.025-0.06 63-70 ≤2.5 Cu base
No5500(MonelK500) ≤0.25 ≤0.5 ≤1.5 ≤0.01 63-70 ≤2 Cu base, Al213-3115,Ti0135-0185
NO5502(Monel502) ≤0.10 ≤0.5 ≤1.5 ≤0.01 63-70 ≤2 Cu base, Al215-315

3.2 Casting alloy: The American cast Monel alloy has five grades of M35-1, M35-2, M-30H, M-25S and M-30C in ASTM A494 (Table 2), which is in the US Federal Standard QQ-N2-88 There are also 5 cast Monel alloys (Table 3).
Table 2. Cast Monel alloy in ASTM A494:

grade name chemical composition /% mechanical properties
C Mn Si P.S Cu Fe Ni Nb Compressive strength/Mpa Tensile strength/Mpa Elongation rate/% HB
M35-1(a) ≤0.35 ≤1.5 ≤1.25 ≤0.03 26-33 ≤3.5 Ba ≥450 ≥170 ≥25
M35-2 ≤0.35 ≤1.5 ≤2.00 ≤0.03 26-33 ≤3.5 Ba ≥450 ≥205 ≥25
M-30H ≤0.30 ≤1.5 2.7-3.7 ≤0.03 27-33 ≤3.5 Ba ≥690 ≥415 ≥10
M-25S ≤0.25 ≤1.5 3.5-4.5 ≤0.03 27-33 ≤3.5 Ba 243-294(b)
M-30C(a) ≤0.30 ≤1.5 1.0-2.0 ≤0.03 26-33 ≤3.5 Ba 1-3 ≥450 ≥225 ≥25 125-130(b)

Notes:
1.Ba=balance, means the balance is all Ni content.
2. To remove the weldability, it should be M3521 or M230C
3. This table is a data parameter
4. HB minimum is 300
Table 3 QQ2N2288 cast Monel alloy:

QQ-N-288 chemical composition /% mechanical properties
C Si Mn Cu Fe Ni Nb Compressive strength/Mpa Tensile strength/Mpa Elongation rate/% HB
A ≤0.35 ≤2.0 ≤1.5 26-33 ≤2.5 62-68 ≥448 ≥224 ≥25 125-150
B ≤0.30 2.7-3.7 ≤1.5 27-33 ≤2.5 61-68 ≥689 ≥455 ≥10 240-290
C ≤0.20 3.3-4.5 ≤1.5 27-31 ≤2.5 ≥60 ≥825 ≥550 ≥10 250-300
D ≤0.25 3.5-4.5 ≤1.5 27-31 ≤2.5 ≥60 ≥300
E ≤0.30 1.0-2.0 ≤1.5 26-33 ≤2.5 ≥60 1-3 ≥448 ≥221 ≥25 125-150

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:
Valve material and valve standards-(8)- Monel alloy application;
Detailed introduction of soft sealing butterfly valve-(2);
Code of valve sealing or lining material;
Classification and advantages of gate valve;

 

Valve actuator / actuation -(3)-classifications

Double acting valve actuator:
The selection of double-acting actuators takes DA series pneumatic actuators as an example. The output torque of

Pneumatic actuator (2)

Pneumatic actuator (2)

the gear-and-pinion actuator is the piston pressure (supplied by the air source pressure) multiplied by the pitch circle radius (arm). And the friction resistance is small and the efficiency is high. The output torque is linear when rotating clockwise and counterclockwise. Under normal operating conditions, the recommended safety factor for double-acting actuators is 25-50%

Single-acting valve actuator:
The selection of single-acting actuator takes the SR series pneumatic actuator as an example. In the application of spring return, the output torque is obtained during two different operations. According to the stroke position, each operation produces two different torque values. The output torque of the spring-return actuator is obtained by multiplying the force (air pressure or spring force) by the force arm. The first situation: the output torque is obtained by air pressure entering the central cavity to compress the spring, which is called “air stroke output torque”. In this case, the air source pressure forces the piston to turn from 0 degrees to 90 degrees. Due to the reaction force generated by the compression of the spring, the torque gradually decreases from the maximum value

hydraulic actuator for marine valve

hydraulic actuator for marine valve

at the starting point to the second condition: the output torque is the spring recovery when the middle cavity loses air. The force acting on the piston is called “spring stroke output torque”. In this case, due to the extension of the spring, the output torque gradually decreases from 90 degrees to 0 degrees. As mentioned above, the single-acting actuator is based on two It is designed on the basis of generating a balance torque under this condition.

Linear valve actuator:
1. Through single seat valve

The so-called single seat means that there is only one valve core and one valve seat in the valve body. Its characteristics are simple structure, small leakage (even completely cut off) and small allowable pressure difference. Therefore, it is suitable for occasions requiring clean media with small leakage and small working pressure difference. Special attention should be paid to the allowable pressure difference in the application to prevent the valve from closing.

2. Straight through double seat valve

There are two valve cores and valve seats in the valve body of the straight-through double-seat regulating valve. Compared with the single seat valve of the same caliber, its flow capacity is about 20% to 25% larger. Because the force of the fluid on the upper and lower valve cores can cancel each other, but the upper and lower valve cores are not easy to close at the same time, the double seat valve has the characteristics of large allowable pressure difference and large leakage. Therefore, it is suitable for clean media where the pressure difference between the two ends of the valve is large and the leakage requirement is not high. It is not suitable for high viscosity and fiber-containing occasions.

3. Angle valve

The valve body of the angle control valve is right-angled, its flow path is simple, and the service force is small. It is suitable for the control of high pressure difference, high viscosity, suspended solids and granular materials. Generally used for bottom inlet and side outlet, this kind of control valve has better stability. In high pressure situations, in order to prolong the service life of the spool, the side inlet and the bottom outlet can be used, but oscillation is prone to occur in small openings.

Classification of valves

Valve classification by function and purpose:

ductile iron, DI, butterfly valve, manufacturer, center line, TH valve

ductile iron, DI, butterfly valve, manufacturer, center line, TH valve

(1) Cut-off type: such as gate valve, globe valve, plug valve, ball valve, butterfly valve, needle valve, diaphragm valve, etc. The cut-off valve is also called a closed-circuit valve or a cut-off valve, whose function is to connect or cut off the medium in the pipeline.

Check valve, also known as one-way valve or check valve, check valve is an automatic valve, its function is to prevent the back flow of the medium in the pipeline, prevent the pump and drive motor from reversing, and the leakage of the container medium . The bottom valve of the pump to close the water is also a check valve.

Explosion-proof valves, emergency valves, etc. The role of safety valves is to prevent the pressure of the medium in the pipeline or device from exceeding the specified value, so as to achieve the purpose of safety protection.

Regulating valve, throttle valve and pressure reducing valve, its role is to adjust the pressure, flow and other parameters of the medium.

(2) Vacuum: such as vacuum ball valve, vacuum baffle valve, vacuum charging valve, pneumatic vacuum valve, etc. Its role is in the vacuum system to change

The vacuum system components that adjust the air flow direction, cut off or connect the pipeline are called vacuum valves.

(3) Special purpose categories: such as pigging valve, vent valve, drain valve, exhaust valve, filter, etc. The exhaust valve is an indispensable auxiliary component in the pipeline system, which is widely used in boilers, air conditioners, oil and gas, and water supply and drainage pipelines. It is often installed at high points or elbows to remove excess gas in the pipeline, improve the efficiency of pipeline use and reduce energy consumption.

According to the main parameters:

According to the nominal pressure:

lug type butterfly valve, ductile iron, center lined,

lug type butterfly valve, ductile iron, center lined,

  • (1) Vacuum valve: refers to a valve whose working pressure is lower than the standard atmospheric pressure.
  • (2) Low pressure valve: refers to the valve with a nominal pressure PN ≤ 1.6Mpa.
  • (3) Medium pressure valve: refers to valves with nominal pressure PN of 2.5Mpa, 4.0Mpa, 6.4Mpa.
  • (4) High-pressure valve: refers to the valve whose nominal pressure PN is 10.0Mpa~80.0Mpa.
  • (5) Ultra-high pressure valve: refers to a valve with a nominal pressure PN≥100.0Mpa.
  • (6) Filter: Refers to the nominal pressure PN is 1.0Mpa, 1.6Mpa

According to working temperature

  • (1) Ultra-low temperature valve: used for valves with medium working temperature t<-101℃.
  • (2) Normal temperature valve: used for valves with medium working temperature -29℃<t<120℃.
  • (3) Medium temperature valve: used for valves with a working temperature of 120℃<t<425℃.
  • (4) High temperature valve: used for valves with medium working temperature t>425℃.

By driving method:

According to the driving mode, it is divided into automatic valves, power-driven valves and manual valves

Valves driven by compressed air. Hydraulic valve: A valve driven by the pressure of liquids such as oil.

In addition, there are combinations of the above several driving methods, such as pneumatic-electric valves.

According to the nominal diameter:

  • (1) Small diameter valve: Valve with nominal diameter DN≤40mm.
  • (2) Middle diameter valve: a valve whose nominal diameter DN is 50~300mm.
  • (3) Large diameter valve: a valve with a nominal valve DN of 350~1200mm.
  • (4) Extra large diameter valves: valves with nominal diameter DN ≥ 1400mm

6. According to structural characteristics:

Valve structure characteristics:

The structural features of the valve can be divided into:

  • (1) Sectional gate shape: The closing part moves along the center of the valve seat; such as a globe valve
  • (2) Cock and ball: The closing part is a plunger or a ball, which rotates around its own centerline; such as a plug valve, a ball valve
  • (3) Gate shape: The closing part moves along the center of the vertical valve seat; such as gate valve, gate, etc.
  • (4) Swing shape: The closing part rotates around the axis outside the valve seat; such as swing check valve, etc.
  • (5) Butterfly shape: the disc of the closing part, which rotates around the axis in the valve seat; such as butterfly valve, butterfly check valve, etc.
  • (6) Slide valve shape: The closing piece slides in a direction perpendicular to the channel. Slippery

Press connection method:

  • (1) Threaded connection valve: The valve body has an internal thread or an external thread, which is connected with the pipe thread…
  • (2) Flange connection valve: The valve body has a flange and is connected to the pipeline flange.
  • (3) Welding connection valve: The valve body has a welding groove and is welded to the pipeline.
  • (4) Clamp connection valve: The valve body has a clamp, which is connected with the pipe clamp.
  • (5) Ferrule connection valve: the ferrule is connected to the pipeline.
  • (6) Wafer connection valve: a connection form in which the valve and two pipes are directly clamped together with bolts.

According to the body material

  • (1) Metal material valve: its valve body and other parts are made of metal material. Such as cast iron valves, cast steel valves, alloy steel valves, copper alloy valves, aluminum alloy valves, lead alloy valves, titanium alloy valves, Monel alloy valves, etc.
  • (2) Non-metallic material valve: its valve body and other parts are made of non-metallic material. Such as plastic valves, enamel valves, ceramic valves, FRP valves, etc.

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:
Notes on selection and installation of butterfly valve;
Classification of check valves;
Classification and advantages of gate valve;
The main classification methods of butterfly valve (1)

Classification and characteristics of ball valve

There are different ways of classification of ball valves.

Function classification:
1. Bypass valve: The ball valve is generally opened by static water, so the bypass valve is set to be pressed first, that is, both sides are filled with water;

ball valve (6)

ball valve (6)

2. Air valve: when filling with water, the buoy will automatically close the valve when the air is removed; when draining, the buoy will drop by itself when it is used for replenishing air;

3. Pressure relief valve: When opening and closing the valve, remove the pressure water between the valve and the sealing cover to avoid wearing the sealing cover;

4. Drain valve: drain the sewage in the lower part of the ball shell.

Transmission classification:
1. Pneumatic ball valve

2. Electric ball valve

3. Hydraulic ball valve

4. Pneumatic hydraulic ball valve

5. Electro-hydraulic ball valve

6. Turbine drive ball valve

Classification characteristics of ball valve:

Ball valves are divided into: floating ball valve, fixed ball valve, orbital ball valve, V-shaped ball valve, three-way ball valve, stainless steel ball valve, cast steel ball valve, forged steel ball valve, ash unloading ball valve, anti-sulfur ball valve, pneumatic ball valve, electric ball valve, card sleeve Ball valves, welded ball valves.

Classified by shell/body material, ball valves can be divided into:

1. Metal material valves: such as carbon steel valves, alloy steel valves, stainless steel valves, cast iron valves, titanium alloy valves, Monel valves, copper alloy valves, aluminum alloy valves, lead alloy valves, etc.

2. Metal valve body lining valves: such as rubber-lined valves, fluorine-lined valves, lead-lined valves, plastic-lined valves, and enamel-lined valves.

3. Valves of non-metallic materials: such as ceramic valves, glass valves, and plastic valves.

There are many domestic manufacturers of ball valves, and most of the connection sizes are not uniform. Mainly divided into the following categories:

The ball of the ball valve is floating. Under the action of the medium pressure, the ball can produce a certain displacement and press tightly on the sealing surface of the outlet end to ensure that the outlet end is sealed.

Structural features of ball valve:
The sealing performance is good, but all the load of the sphere bearing the working medium is transmitted to the outlet sealing ring. Therefore, it is necessary to consider whether the sealing ring material can withstand the working load of the sphere medium. When subjected to higher pressure impact, the sphere may deviate . This structure is generally used for medium and low pressure ball valves.

The ball of the ball valve is fixed and does not move when pressed. The fixed ball valve is equipped with a floating valve seat. After receiving the pressure of the medium, the valve seat will move, so that the sealing ring is pressed tightly on the ball to ensure sealing. Bearings are usually installed on the upper and lower shafts of the ball, and the operating torque is small, which is suitable for high pressure and large diameter valves.

In order to reduce the operating torque of the ball valve and increase the reliability of the seal, an oil-sealed ball valve has appeared, which not only injects a special lubricant between the sealing surfaces to form a layer of oil film, which enhances the sealing performance and reduces the operating torque. Suitable for high pressure and large diameter ball valves.

Flexible features of ball valve:

The ball of the ball valve is elastic. Both the ball and the valve seat sealing ring are made of metal materials, and the sealing specific pressure is very large. The pressure of the medium itself cannot meet the sealing requirements, and external force must be applied. This valve is suitable for high temperature and high pressure media.

The elastic sphere is made by opening an elastic groove on the lower end of the inner wall of the sphere to obtain elasticity. When closing the passage, use the wedge-shaped head of the valve stem to expand the ball and press the valve seat to seal. Loosen the wedge-shaped head before rotating the sphere, and the sphere will return to its original shape, so that there is a small gap between the sphere and the valve seat, which can reduce the friction and operating torque of the sealing surface.

Qv347, Qv647, Qv947 V-type regulating ball valve

The Qv347, Qv647, and Qv947 V-type regulating ball valves have a shearing effect on the valve seat because the ball core has a V-shaped structure. Therefore, it is suitable for the control of relevant process parameters in the suspension medium containing fibers or small solid particles in papermaking, chemical, metallurgical and other industrial enterprises. It is especially suitable for the pulp, white water, black liquor and white water in the pulp and paper production process. Automatic adjustment of the fluid of suspended particles such as liquid and thick and turbid slurry fluid medium.

This V-shaped ball valve is a fixed ball valve and also a single-seat sealed ball valve. The adjustment performance is the best among ball valves, the flow characteristics are equal percentages, and the adjustable ratio is 100:1. It has a shearing effect between the V-shaped incision and the metal valve seat, which is especially suitable for media containing fibers, small solid particles, slurry, etc.

Three-way ball valve has T type and L type. The T type can connect three orthogonal pipelines with each other and cut off the third channel, which can split and merge. The L-shape can only connect two orthogonal pipelines, and cannot maintain the third pipeline to communicate with each other at the same time. It only plays a role of distribution.

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…)