Knowledge Archives

Why is austenitic stainless steel magnetic

November 11, 2021

In the procurement case of austenitic stainless steel butterfly valves or gate valves, we can often find an interesting phenomenon. Customers carry magnets with them to check whether the material of the product is genuine. I think it is really “stainless steel” if it can’t be absorbed, and it’s faked with “stainless iron” if it sucks. This is really an “unjust case”. Today this article will share the unscientific aspects of this method.

high performance-double eccentric-butterlfy valve-wafer-lug-flanged (5)

The main reason for the emergence of the magnet inspection method is the recognition of a characteristic of austenitic stainless steel, that is, everyone must know that austenite is non-magnetic or weakly magnetic, while martensite or ferrite is magnetic. . Stainless steel is classified according to its organizational structure at room temperature: 1. Austenite type: such as 304, 321, 316, 310, etc.; 2． Martensite or ferrite type: such as 430, 420, 410, etc.; however, everyone ignores the change in ferrite content caused by the difference in forging and casting processes. This kind of magnetism, which is caused by chemical composition fluctuations or different processing conditions caused by smelting, cannot be regarded as counterfeit or substandard. Let’s see why?
1. During smelting, if composition segregation or improper heat treatment, a small amount of martensite or ferrite structure will appear in austenitic stainless steel. In this way, the austenitic stainless steel gate valve will have weak magnetism.
2. After austenitic stainless steel is cold-worked, the structure will also be transformed into magnetic martensite. The greater the degree of cold-working deformation, the more martensite transformation and the greater the magnetic properties of the steel.

marine valve; butterfly valve; check valve; gate valve; manufacturer in China

3. When polishing the product, use an iron wrist to polish it. If it is not cleaned or there are iron filings on the surface, it will show magnetism.
However, the magnetism of austenitic stainless steel caused by the above reasons is not at the same level as that of other stainless steels, such as 430 and carbon steel. That is to say, even if austenitic steel shows a certain degree of weak magnetism, it makes the magnet feel When it comes to suction, it is by no means strong magnetism, and the product itself is still qualified. In other words, if the austenitic stainless steel gate valve is weakly magnetic or non-magnetic at all, it should be judged as 304 or 316 austenitic stainless steel. If the magnetism is the same as that of carbon steel and shows strong magnetism, the product material is not austenitic steel but other materials are used indiscriminately.
If manufacturers want to completely eliminate the magnetic properties of austenitic stainless steel caused by the above reasons, they can restore and stabilize the austenitic structure through high-temperature solution treatment, thereby eliminating the magnetic properties. At the same time, select sand with high silicon content during forging and polishing treatment and then pickling passivation to remove magnetism. At the same time, as a user, when we are purchasing, we also recommend to choose products from reputable manufacturers, not to be greedy for cheap prices and avoid being deceived.

Therefore, it is unscientific to use a magnet to detect whether austenitic stainless steel contains magnetism.

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife 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

electric fluorine-lined butterfly valve vs electric metal seated butterfly valve

August 2, 2021

The difference between electric fluorine-lined butterfly valve and electric hard seal butterfly valve
Electric butterfly valve is one of the most commonly used valves in industrial pipelines in recent years. In addition to ordinary opening and closing, it can also be used to adjust and control the pressure, flow, temperature and other parameters of various water, liquid, gas and other fluids. An important execution unit in the field of automation control, is widely used in chemical, electric power, petroleum, metallurgy, steam, environmental protection, fire-fighting systems and other occasions! In addition, there are many types of electric butterfly valves and various control modes, which can meet the requirements of various working conditions!

Fluorine lined butterfly valve-PTFE-WAFER (10)

Electric fluorine-lined butterfly valves and electric hard-sealed butterfly valves are the two most commonly used types of butterfly valves. The applicable medium and pressure temperature are completely different! But many people’s choice between the two often seems a bit uncertain! In the simplest terms, the two control modes are the same, the difference is the sealed structure. The electric fluorine-lined butterfly valve is suitable for corrosive media, but it can only be used at room temperature and pressure. The electric hard seal butterfly valve can be used for various pressures. temperature range! The detailed differences are as follows:
Electric fluorine-lined butterfly valve Electric hard-sealed butterfly valve
1. From the structure:
The hard sealing butterfly valve refers to that both sides of the sealing pair are made of metal materials or other harder materials. For soft sealing butterfly valves, the two contacting sealing surfaces can be separate or all of soft materials. For example, fluorine-lined butterfly valve means that the butterfly plate and valve seat are both wrapped in PTFE;

D943H-16C-metal seated stainless steel electric triple offset butterfly valve

2. From the sealing performance:
The advantage of soft-sealed fluorine-lined butterfly valve is good sealing performance, but the disadvantage is that it is easy to age, wear, and has a short service life. The hard seal butterfly valve has a long service life, but the sealing performance is relatively worse than that of the soft seal.
3. From the conditions of use:
The soft-sealed fluorine-lined butterfly valve is used in normal temperature and pressure environment, and the hard-sealed butterfly valve can be used in low temperature, normal temperature, high temperature and other environments. Generally, it can be used for higher pressure, but the soft seal is not. However, the fluorine-lined butterfly valve has super corrosion resistance!
4. From the manufacturing point of view:
As for manufacturing, from a principle point of view, there is little difference between the two, mainly the difference in valve seats. The soft-seal fluorine-lined butterfly valve is a non-metallic structure, and the hard-seal butterfly valve is a metal structure. The hardness relationship between metals and the workmanship must be considered. Situation, what medium to go and so on.
Related knowledge: Working principle diagram of electric butterfly valve Selection of electric wafer butterfly valve and flange butterfly valve

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife 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, API

Single eccentric|double eccentric|triple eccentric butterfly valve structure principle (diagram)

July 30, 2021

The evolution of butterfly valve sealing structure: single eccentric butterfly valve, double eccentric butterfly valve and triple eccentric butterfly valve

Butterfly valves have been widely used due to their low cost, small size, light weight and long life. With the development of my country’s industry, various industries have more and more stringent requirements for the performance of equipment, especially in some gas pipelines or other hazardous material pipelines, the butterfly valve must achieve zero leakage, so the sealing structure design of the butterfly valve has always been important Research topics.

With the rapid development of modern industrial technology, butterfly valves are widely used in pipeline control systems, especially large-diameter pipeline control systems where other control valves are difficult to apply. Generally, the valve seat of the butterfly valve is a fixed type, and its materials are polymer and metal. The polymer valve seat is mainly suitable for working conditions with lower temperature. Although the metal seat butterfly valve can meet the higher temperature and pressure However, the elasticity of the metal valve seat is lower than that of the polymer valve seat, and the sealing performance is poor. The improvement of various performances of butterfly valves is closely related to its continuous improvement. For example, the development of butterfly valve sealing structure technology has successively experienced the evolution process of ordinary butterfly valve, single eccentric butterfly valve, double eccentric butterfly valve and triple eccentric butterfly valve.

Since the rotation center of the butterfly plate (that is, the center of the valve shaft) and the sealing section of the butterfly plate are set eccentrically according to a, the butterfly plate sealing surface gradually separates from the valve seat sealing surface during the opening process of the butterfly valve, and the butterfly plate rotates to 20°～25° , The sealing surface of the butterfly plate is completely separated from the sealing surface of the valve seat. When the valve is fully opened, a gap x is formed between the two sealing surfaces, so that the relative mechanical wear and extrusion between the two sealing surfaces of the butterfly valve is greatly reduced during the opening and closing process. Ensure the sealing of the butterfly valve.

Since the rotation center of the butterfly plate (that is, the center of the valve shaft) and the center line of the valve body are offset by size b on the basis of the single eccentric butterfly valve, the sealing surface of the butterfly plate will be faster than the single eccentric sealing butterfly valve during the opening process of the butterfly valve. When the butterfly plate rotates to 8°～12°, the butterfly plate sealing surface is completely separated from the valve seat sealing. When it is fully opened, a larger gap y is formed between the two sealing surfaces. This type of butterfly valve is designed , Which greatly reduces the mechanical wear and extrusion deformation between the two sealing surfaces, and improves the sealing performance of the butterfly valve.

There are different types of eccentric sealing butterfly valves, and the fields of application and their respective characteristics are naturally different. But fundamentally speaking, the basic principles of eccentric sealing butterfly valves are similar.

Structural characteristics of single eccentric butterfly valve:

single eccentric butterfly valve structure diagram

1. The center of rotation of the disc plate (that is, the center of the valve shaft) is located on the center line of the valve body, and an A-size offset is formed on the sealing section of the valve plate. The single eccentric butterfly valve is that the rotation center of the disc plate is on the center line of the valve body, and the valve plate deviates a distance from the sealing surface, which is suitable for soft sealing.
2. When the valve is closed, the valve seat and the sealing surface of the valve plate are in a relatively interference contact state. To achieve the seal, it is mainly by pressing the sealing ring to expand in the peripheral direction to produce the sealing specific pressure and the pipeline pressure against the valve plate. It can only be sealed in one direction because of the strong force.
3. When the valve is opened, the contact side of the valve plate and the valve seat is separated from the valve seat, and the other side is always two-point contact along the axial direction of the half circumference. Repeated opening and closing of the sealing ring is easy to be damaged, which affects the sealing performance. It is impossible to achieve a metal seal.
4. From a geometric point of view, it is obvious that X does not exist in the above figure, and in turn there is a certain amount of interference.
Structural features of double eccentric butterfly valve:

double eccentric butterfly valve structure diagram

The center of rotation of the valve plate (that is, the center of the valve shaft) forms an offset of dimension A on the sealing section of the valve plate, and forms an offset of dimension B with the center of the valve body.
Since the center line of the valve seat and the center line of the valve body form a β angle offset on the basis of the double eccentric butterfly valve, the sealing surface of the butterfly plate immediately leaves the sealing surface of the valve seat at the moment of opening during the valve opening process of the butterfly valve. Only at the moment of closing does it contact and compress the seat sealing surface. When fully opened, a gap y is formed between the two sealing surfaces, which is the same as that of the double eccentric sealing butterfly valve. The design of this type of butterfly valve completely eliminates the mechanical wear and abrasion between the two sealing surfaces, making the butterfly valve more effective in its sealing performance and use. The life span has been greatly improved.

Structural features of triple eccentric butterfly valve:

triple eccentric butterfly valve structure diagram

The center of rotation of the valve plate (that is, the center of the valve shaft) forms an offset A on the sealing section of the valve plate, and an offset b from the center of the valve body; the centerline of the valve body sealing surface and the centerline of the valve seat (ie the centerline of the valve body) An angular offset of β is formed.
The uniqueness of the triple eccentric butterfly valve is that the stem shaft on which the butterfly plate is installed is a three-segment shaft structure. This three-segment shaft type valve stem has two shaft sections concentric, and the center line of the central shaft is deviated from the two ends of the axis by a center distance. , The butterfly plate is installed on the intermediate shaft section. Such an eccentric structure makes the butterfly plate a double eccentric shape when in the fully open position, and a single eccentric shape when the butterfly plate rotates to the closed position. Due to the effect of the eccentric shaft, when it is close to closing, the butterfly plate moves a distance into the sealing cone surface of the valve seat, and the butterfly plate matches the sealing surface of the valve seat to achieve reliable sealing performance.
Related Knowledge: Common Sense of Eccentric Butterfly Valve

Related Products: Electric Triple Eccentric Butterfly Valve Pneumatic Triple Eccentric Butterfly Valve

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife 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

Pneumatic butterfly valve installation instructions

July 29, 2021

Pneumatic butterfly valve installation instructions and steps
Whether the pneumatic butterfly valve is installed well will affect the efficiency of the equipment. And the maintenance of the pneumatic butterfly valve is also related to the performance of the equipment. Improper installation or lack of maintenance will cause the performance of the butterfly valve to decline, and even unnecessary dangers. The user should check and maintain the pneumatic butterfly valve as scheduled.

D673H-16C-stainless steel pneumatic triple eccentric butterfly valve

1. Before installation, check that all parts of the pneumatic butterfly valve are not missing, the model is correct, there is no debris in the valve body, and there is no blockage in the solenoid valve and muffler;
2. Put the valve and cylinder in the closed state.
3. Hit the cylinder against the valve (the installation direction is either parallel or perpendicular to the valve body), and then check whether the screw holes are aligned, there will be no too much deviation, if there is a little deviation, just rotate the cylinder body a little. , And then tighten the screws.
4. After installation, debug the pneumatic butterfly valve (the air supply pressure is 0.4~0.6MPa under normal circumstances), and the solenoid valve must be opened and closed manually during the debugging operation (the solenoid valve coil can only be operated manually after the solenoid valve coil is de-energized). Observe the opening and closing of the pneumatic butterfly valve. If the valve is found to be a bit difficult at the beginning of the opening and closing process during the debugging operation, and then it is normal, you need to reduce the stroke of the cylinder (the stroke adjustment screws at both ends of the cylinder should be adjusted inward at the same time, and the valve should be moved to the open position during adjustment. , Then turn off the air source and adjust again) until the valve opens and closes smoothly and closes without leakage. It should also be noted that the adjustable silencer can adjust the opening and closing speed of the valve, but it should not be adjusted too small, otherwise the valve may not operate.
5. Defa should be kept dry before installation, and should not be stored in the open air;
6. Check the pipeline before installing the butterfly valve to ensure that there is no foreign matter such as welding slag in the pipeline;
7. The manual opening and closing resistance of the butterfly valve body is moderate, and the torque of the butterfly valve matches the torque of the selected actuator.
8. The flange specification for butterfly valve connection is correct, and the pipe clamp flange conforms to the

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

butterfly valve flange standard. It is recommended to use special flanges for butterfly valves instead of flat welding flanges.
9. Confirm that the flange welding is correct. After the butterfly valve is installed, the flange must not be welded to avoid scalding the rubber parts.
10. The installed pipe flange should be centered and centered with the inserted butterfly valve.
11. Install all the flange bolts and tighten them by hand. It will be confirmed that the butterfly valve and the flange have been aligned, and then the butterfly valve will be opened and closed carefully to ensure flexible opening and closing.
12. Fully open the valve. Use a wrench to tighten the bolts in diagonal order. No washers are needed. Do not overtighten the bolts to prevent serious deformation of the valve ring and excessive opening and closing torque.
Related knowledge: Installation instructions for ventilation butterfly valves; Installation instructions for telescopic butterfly valves

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife 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

Structural characteristics of metal hard seal butterfly valve

July 29, 2021

Structural characteristics of metal hard seal butterfly valve
The metal hard seal butterfly valve is mainly composed of valve body, butterfly plate, valve shaft, valve body sealing ring, butterfly plate sealing ring, shaft sleeve, self-lubricating bearing, driving device and so on. The high-performance metal hard seal butterfly valve drives the valve shaft to rotate through various driving devices, and the pin shaft drives the butterfly plate to rotate within 90°, so that the butterfly plate is in the open or closed state, so as to achieve the purpose of connecting or cutting off. It is widely used in metallurgy, hydropower, thermal power, thermal power, urban water supply and drainage, farmland irrigation and drainage and other industries. The applicable medium is gas, steam, air, water, etc., in the pipeline system.

triple eccentric butterfly valve-lug

Structural features of metal sealing butterfly valve:
①The unique design of three-way eccentricity enables frictionless transmission between the sealing surfaces and prolongs the service life of the valve.
②The elastic seal is produced by the torque.
③The ingenious wedge-shaped design makes the valve have the function of automatic sealing as the valve closes tighter and tighter, and the sealing surface has compensation and zero leakage.
④Small size, light weight, light operation, easy to install.
⑤Pneumatic and electric devices can be configured according to user requirements to meet the needs of remote control and program control.
⑥The material of replacement parts can be applied to various media, and can be lining anti-corrosion (lining F46, GXPP, PO, etc.).
⑦The sealing ring is made of stainless steel, which has the dual advantages of metal hard seal and elastic seal. It has excellent sealing performance regardless of low temperature and high temperature.
The difference between metal hard seal butterfly valve and rubber seal butterfly valve:
The disadvantage of the rubber seal butterfly valve is that when it is used for throttling, cavitation will occur due to improper use, causing the rubber seat to peel off and damage. For this reason, the metal sealing butterfly valve has been developed internationally. The metal hard sealing butterfly valve is an eccentric metal sealing structure, and the sealing form is metal to metal sealing. The metal sealing ring can be exchanged for metal sealing, and the stainless steel plate and graphite composite plate sealing ring is sealing to metal. .

The high-performance elastic metal sealing butterfly valve adopts a double eccentric and a special oblique cone oval sealing structure. It solves the shortcoming of the traditional eccentric butterfly valve that the sealing surface is still in sliding contact friction at the moment of opening and closing 0°～10°, and the sealing surface of the butterfly plate is separated at the moment of opening, and the effect of closing the contact is sealing, so as to extend the service life and maximize the sealing performance.
Related knowledge: the principle of butterfly valve structure
Related products: Electric hard-sealed butterfly valve Pneumatic hard-sealed butterfly valve

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife 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

Pneumatic butterfly valve working principle diagram

July 28, 2021

Pneumatic butterfly valve working principle diagram
Pneumatic butterfly valve is a kind of general-purpose valve that is particularly widely used. Nowadays, many chemical industry, paper industry, coal industry, petroleum, medical, etc. will use valves, especially pneumatic valves, and if the use is relatively large, it must be Pneumatic butterfly valves are extremely common on many pneumatic pipelines! Especially in low-pressure large and medium-caliber pipelines, it is used more and more. The larger the diameter, the more economical and economical than other valves.

Double offset-butterfly valve-D972F-150lbC (1)

Pneumatic butterfly valves are so widely used because of their simple structure, easy maintenance, and rapid switching, which can not only improve work efficiency, but also reduce maintenance time. According to customer requirements, seal rings of different materials and parts of different materials can be selected to be suitable for different media and working conditions, so that the pneumatic butterfly valve can achieve great results.
Working principle of pneumatic butterfly valve:
The pneumatic butterfly valve uses compressed air as the power source, and drives the valve stem to control the disc-shaped butterfly plate to rotate around the axis. The initial position of the valve is determined according to actual needs. When the valve rotates 90° from the initial position, an action ends (by opening To off, or from off to on), otherwise, another action (from off to on, or from on to off) ends.
The execution speed of the pneumatic butterfly valve is relatively fast, it is not easy to be damaged due to jamming during the movement process, and does not require the hands of workers. It can not only be used as a cut-off valve, but also can be equipped with a valve positioner to achieve the function of regulating and controlling the pipeline medium. Pneumatic butterfly valve actuators are divided into single-acting and double-acting forms. The double-acting is vent opening and vent closing! Among them, the single-acting actuator has a spring return function, which can be

U-type flange butterfly valve, ductile iron, DI, center line,

automatically closed or opened in the case of gas or power failure, with a high safety factor!
Related knowledge: dynamic diagram of butterfly valve working principle
Recommended products: Pneumatic regulating butterfly valve Pneumatic triple eccentric butterfly valve

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife 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

electric wafer butterfly valve vs electric flange butterfly valve

July 27, 2021

The difference and selection of electric wafer butterfly valve and electric flange butterfly valve
As one of the most common valves in pipelines, electric butterfly valves are used to realize the on-off and flow control of various media in the pipeline system. They have been widely used in many fields such as petroleum, chemical industry, metallurgy, and hydropower. application. Then in the commonly used electric butterfly valve, it can be

D673H-16C-stainless steel pneumatic triple eccentric butterfly valve

divided into two kinds, electric wafer butterfly valve and electric flange butterfly valve, and these two kinds of valves have their own characteristics, and they are not the same in performance. They can be used in Different industries.

For these two kinds of valves, in addition to the different structural forms, if they are under the same parameters, the biggest difference is that the connection method is different, that is, the installation form is different, which depends on the site working conditions!

The difference between electric wafer butterfly valve and electric flange butterfly valve:
The thickness of the electric wafer butterfly valve is relatively thin compared to the flanged butterfly valve. There are no flanges at both ends of the valve body, but only a few guide bolt holes. The valve uses a set of bolts/nuts to connect with the flange of the pipe end, which is generally applicable. It is used in places where the space is relatively narrow or the pipeline is restricted. The advantage is that it is more convenient to disassemble, the valve cost is lower, and the space is small, but the disadvantage is that one sealing surface has a problem, and both sealing surfaces have to be disassembled!
Electric flange butterfly valve has flanges at both ends of the valve body, which are connected with pipeline flanges. Compared with wafer butterfly valves, the sealing performance is more reliable. It is generally used in places with larger diameters or higher pressures, but the cost is relatively good.

D943H-16C-metal seated stainless steel electric triple offset butterfly valve

Choice between the two:
However, there are still some things to pay attention to in the design. For example, wafer type valve bolts are generally relatively long. Under high temperature conditions, the expansion of the bolts may cause leakage, so it is not suitable for large pipe diameters under high temperature conditions. . Another example is the wafer butterfly valve generally cannot be used in the end of the pipeline and downstream needs to be disassembled, because when the downstream flange is removed, the wafer valve will fall off, in this case, it must be shortened separately. The flange type butterfly valve does not have the above problems, but the cost will be higher.
Related Electric butterfly valve series products View other butterfly valves

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife 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

Advantages and disadvantages of butterfly valve and structure diagram

July 26, 2021

Advantages and disadvantages of butterfly valve and structure diagram
The butterfly valve opening and closing part is a disc-shaped butterfly plate, which rotates around its own axis in the valve body to achieve opening and closing or adjustment. The butterfly valve is usually less than 900 from fully open to fully closed. The butterfly valve and the butterfly rod themselves are not self-locking. For the positioning of the butterfly plate, a worm gear reducer must be installed on the valve rod. The use of worm gear reducer can not only make the disc plate have self-locking ability, make the disc plate stop at any position, but also improve the operation performance of the valve.

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

The industrial butterfly valve is characterized by high temperature resistance, high applicable pressure range, large nominal diameter of the valve, the valve body is made of carbon steel, and the sealing ring of the valve plate uses a metal ring instead of a rubber ring. The large high temperature butterfly valve is made of steel plate welding, and is mainly used for flue ducts and gas pipes of high temperature media.
(1) Advantages of butterfly valve:
1. It is convenient and quick to open and close, labor-saving, low fluid resistance, and can be operated frequently.

Wafer and Lug type butterfly valve structures & parts

2. Simple structure, small size and light weight.
3. Mud can be transported, and the accumulation of liquid at the pipe mouth is the least.
4. Under low pressure, good sealing can be achieved.
5. Good adjustment performance.
(2) Disadvantages of butterfly valves:
1. The working pressure and working temperature range are small.
2. Poor airtightness.
(3) Installation and maintenance of butterfly valve:
1. During installation, the valve disc should be stopped in the closed position.
2. The opening position should be determined according to the rotation angle of the butterfly plate.
3. For the butterfly valve with bypass valve, the bypass valve should be opened before opening.
4. The installation should be carried out according to the installation instructions of the manufacturer, and the heavy-weight butterfly valve should be installed with a firm foundation.
Related knowledge: the principle of butterfly valve structure

Double flange butterfly valve structure

Related products: Electric butterfly valve Pneumatic butterfly valve

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife 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

Fluorine-lined butterfly valve vs metal seated butterfly valve

July 23, 2021

The difference and selection of fluorine-lined butterfly valve and metal seated butterfly valve
As one of the most commonly used valves in process pipelines, butterfly valves are not only simple in structure, easy to operate, and equipped with different driving devices, but also can form a variety of control methods, such as electric butterfly valves, hydraulic butterfly valves, pneumatic butterfly valves, etc.! Moreover, butterfly valves are often used in occasions with large caliber and flow. Compared with other valves of the same caliber, the cost can be reduced by 1.5 to 2 times, which is economical and practical!

Fluorine lined butterfly valve-PTFE-DOUBLE FLANGE (2)

According to the different sealing forms of butterfly valves, they can be divided into two categories, one is soft seal and the other is metal seated! The two butterfly valves with different sealing forms play different roles in the relatively used pipelines. In a sense, there are still big differences! When choosing, users should have a detailed understanding and awareness of the difference between the two!

Take the most common soft-sealed fluorine-lined butterfly valves and metal hard-sealed butterfly valves, fluorine-lined butterfly valves are generally used for pipelines containing corrosive media, and the sealing effect can reach zero leakage, but it is only suitable for normal temperature and pressure! The hard-sealed butterfly valve is relatively high in temperature and pressure, but the sealing and corrosion resistance are not as good as the soft-sealed butterfly valve!
1. From the structure: The metal seated butterfly valve refers to the metal material or other harder materials on both sides of the sealing pair. For soft sealing butterfly valves, the two contacting sealing surfaces can be separate or all of soft materials. For example, fluorine-lined butterfly valve means that the butterfly plate and valve seat are both wrapped in PTFE;

triple offset butterfly valve-double flange- (5)

2. In terms of sealing performance: The advantage of the soft-sealed fluorine-lined butterfly valve is that it has good sealing performance, but the disadvantage is that it is easy to age, wear, and has a short service life. The metal seated butterfly valve has a long service life, but the sealing performance is relatively worse than that of the soft seal.
3. From the conditions of use: The soft-sealed fluorine-lined butterfly valve is used in normal temperature and pressure environments, while the hard-sealed butterfly valve can be used in low temperature, normal temperature, high temperature and other environments. Generally, it can be used for higher pressure, but the soft seal is not. However, the fluorine-lined butterfly valve has Super corrosion resistance!
4. From the manufacturing aspect: As for the manufacturing, from the principle point of view, the difference between the two is not big, mainly the difference in the valve seat. The soft-sealed fluorine-lined butterfly valve is a non-metallic structure, and the hard-sealed butterfly valve is a metal structure. It is necessary to consider the metal structure. The relationship between the hardness, the working conditions, what medium is used, and so on.

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife 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

The difference between globe valve and gate valve

July 23, 2021

The difference between globe valve and gate valve, The difference between gate valve and globe valve

From the structure:
The length of the gate valve is shorter than that of the stop valve, and the height is higher than that of the stop valve. The installation of the rising stem gate valve should pay attention to the height. This should be paid attention to when the installation space is limited. The gate valve can be tightly closed with the sealing surface depending on the medium pressure, so as to achieve the effect of no leakage. When opening and closing, the valve core and the valve seat sealing surface are always in contact and rub against each other, so the sealing surface is easy to wear. When the gate valve is close to closing, the pressure difference between the front and rear of the pipeline is large, which makes the sealing surface wear more serious.

globe valve structure diagram

gate valve structure diagram

In principle:
The difference between the globe valve and the gate valve in principle is that the globe valve is a rising stem type, and the hand wheel rotates and rises together with the stem. In the gate valve, the hand wheel rotates and the valve stem moves upward. The flow rate is different, the gate valve is required to be fully open or fully closed, but the stop valve is not required. The shut-off valve has specified inlet and outlet directions; the gate valve has no inlet and outlet direction requirements.
Schematic diagram of gate valve Schematic diagram of globe valve
Explanation: The flow part of the gate valve is also the same as the straight pipe, but a gate is set in the pipe. If the gate is lifted up, the door will be fully opened, and the fluid of the stop valve will turn inside the valve. A 180-degree bend, usually the fluid enters from one side of the valve and after entering the valve, the fluid flows upward at a 90-degree angle, and then flows through the upper part of the valve body and then turns a 90-degree flow out, just as the fluid flows inside the valve. A cover is added to the upper outlet, the cover is closed and the door is closed, and the valve is opened when the cover is opened.

From the flow up:
The shut-off valve is low in and high out. From the outside, it is obvious that the pipeline is not on the horizontal line of one phase. The gate valve flow path is on a horizontal line. The stroke of the gate valve is larger than that of the stop valve.

globe cut-off valve working diagram-3D GIF animated presentation-flow direction

Explanation: From the perspective of flow resistance, the flow resistance of the gate valve is small when it is fully opened, and the flow resistance of the load stop valve is large. The flow resistance coefficient of ordinary gate valve is about 0.08~0.12, the opening and closing force is small, and the medium can flow in two directions. The flow resistance of ordinary globe valves is 3-5 times that of gate valves. When opening and closing, it needs to be forced to close to achieve the seal. The valve core of the stop valve does not contact the sealing surface when it is completely closed, so the wear of the sealing surface is very small. The stop valve that needs to add an actuator due to the main flow force should pay attention to the torque control mechanism Adjustment.

gate valve working diagram-3D GIF animated presentation-flow direction

From the installation:
1. The flow direction of the gate valve is the same when entering from both sides.
2. There are two ways to install the shut-off valve. One is that the medium can enter from below the valve core. The advantage is that the packing is not stressed when the valve is closed, which can prolong the service life of the packing and can be piped in front of the valve. Under pressure, the packing should be replaced; the disadvantage is that the driving torque of the valve is relatively large, which is about 1 times that of the upper flow, and the axial force on the valve stem is large, and the valve stem is easy to bend. Therefore, this method is generally only suitable for small-diameter stop valves (below DN50). For stop valves above DN200, the medium flows in from above. (The electric shut-off valve generally adopts the way that the medium enters from above.) The shortcoming of the medium entering method from above is just the opposite of that of the downward entering method.

From the sealing surface:
The sealing surface of the globe valve is a small trapezoidal side of the valve core (see the shape of the valve core for details). Once the valve core falls off, it is equivalent to closing the valve (if the pressure difference is large, of course the closing is not tight, but the anti-reverse effect is not bad). The gate valve is sealed by the side of the valve core gate plate, the sealing effect is not as good as the stop valve, and the valve core will not be closed like the stop valve when the valve core falls off.

You can check the detailed data sheet /specification /structure diagram /sizes /materials of

globe valve on:https://www.tanghaivalve.com/wp-content/uploads/2021/05/500-api-jis-globe-valve-cast-steel-forged-steel.pdf gate valve: https://www.tanghaivalve.com/wp-content/uploads/2021/05/301-data-sheet-gate-valve-th-valve.pdf

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife 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

Why is austenitic stainless steel magnetic

electric fluorine-lined butterfly valve vs electric metal seated butterfly valve

Single eccentric|double eccentric|triple eccentric butterfly valve structure principle (diagram)

Pneumatic butterfly valve installation instructions

Structural characteristics of metal hard seal butterfly valve

Pneumatic butterfly valve working principle diagram

electric wafer butterfly valve vs electric flange butterfly valve

Advantages and disadvantages of butterfly valve and structure diagram

Fluorine-lined butterfly valve vs metal seated butterfly valve

The difference between globe valve and gate valve

TH VALVE • PROFESSIONAL VALVE MANUFACTURER

GET IN TOUCH WITH US