triple offset butterfly valve Archives

What is the principle of triple eccentric butterfly valve

February 11, 2022

Triple eccentric butterfly valve is a kind of butterfly valve with outstanding performance in industrial pipelines. According to the sealing form, triple eccentric butterfly valve belongs to the category of hard sealing butterfly valve. Therefore, the triple eccentric butterfly valve has the characteristics of a hard-sealed butterfly valve, which is

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

resistant to high temperature, erosion, and has a long service life. And because the triple eccentric butterfly valve directly welds the high temperature corrosion resistant alloy material on the valve seat surface, the valve also has the same excellent sealing performance as the soft sealing butterfly valve. So what is the principle of triple eccentric butterfly valve? What are the three eccentricities of the triple eccentricity? Why use a triple eccentric structure?

The sealing surface of the triple eccentric butterfly valve is an inclined conical surface. The valve seat of the valve body is in contact with the sealing ring of the butterfly plate. Its working principle is to drive the movement of the butterfly plate by operating the transmission device. During the movement of the butterfly plate, its sealing The ring is in full contact with the valve seat because of the elastic deformation to achieve the seal.
A prominent feature of the triple eccentric butterfly valve is that the sealing structure of the valve is changed. It is no longer a traditional position seal, but a torsion seal, that is to say, it does not rely on the elastic deformation of the valve seat to achieve sealing, but relies on the sealing surface of the butterfly plate. The contact surface pressure with the valve

triple eccentric butterfly valve-wafer-lug-double flange-welded (5)

seat is used to achieve the sealing effect, which also solves the problem of large leakage of the metal valve seat, and because the contact surface pressure is proportional to the medium pressure, the triple eccentric butterfly valve has a strong high pressure and high temperature resistance.

Three eccentric butterfly valve three eccentric
The first eccentricity: the deviation from the plane of the sealing surface to the centerline of the valve stem;
The second eccentricity: the distance from the centerline of the valve body to the centerline of the stem;
The third eccentricity: there is an included angle between the center line of the cone surface where the sealing surface of the valve body is located and the center line of the valve body channel.

Reasons for using triple eccentric structure
The use of triple eccentric structure can reduce the friction between the sealing surface of the disc and the sealing surface of the valve body when opening or closing, so that the disc can quickly disengage or release the valve seat when the triple eccentric butterfly valve is opened or closed, reducing the operation time. torque, the operation is more labor-saving and light, and the service life of the sealing surface of the butterfly valve is increased.

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

Video of triple eccentric butterfly valve:

Advantages and Disadvantages of Triple Eccentric Butterfly Valves

January 21, 2022

The triple eccentric butterfly valve is a new type of butterfly valve product. Before the advent of the triple eccentric butterfly valve, the soft sealing butterfly valve and the single eccentric double eccentric metal hard sealing butterfly

triple eccentric butterfly valve-

valve were the most used in industrial pipelines. These two types of butterfly valves have their own advantages, but also have obvious disadvantages. The advantage of soft sealing butterfly valve is that it has good sealing performance and can achieve zero leakage; the disadvantage is that it is not suitable for high temperature and high pressure environment and is not resistant to wear. The advantage of hard sealing butterfly valve is that it can adapt to high temperature and high pressure working conditions, but the sealing performance is very poor. In order to solve the shortcomings of the two types of butterfly valves and better serve our production work, the triple eccentric butterfly valve came into being and has been widely used.

Advantages of triple eccentric butterfly valve
The triple eccentric butterfly valve also belongs to the metal hard sealing butterfly valve. The technology makes the triple eccentric butterfly valve more resistant to high temperature and high pressure environment and more corrosion resistant than traditional butterfly valve products. At the same time, due to the unique design of the triple eccentricity, the valve is very easy to operate. When opening and closing, the disc and the valve body have no friction. When the valve is closed, the torque of the transmission mechanism increases to provide a compensation seal, which greatly improves the triple eccentricity. The sealing performance of the butterfly valve also prolongs the service life of the butterfly valve. So what do the three eccentricities of the triple eccentricity mean?
1st eccentric: The valve shaft is located behind the valve plate shaft, allowing the seal to have a complete tight encircling contact with the entire valve seat.
The second eccentricity: the centerline of the valve shaft is offset from the centerline of the pipe and valve, which is free from the interference of valve opening and closing.
3rd eccentricity: The valve seat cone shaft is offset from the centerline of the valve shaft, which eliminates friction during closing and opening and achieves a uniform compression seal around the entire valve seat.

Disadvantages of triple eccentric butterfly valve
No matter how perfect things are, there will be more or less defects and imperfections, and the triple eccentric butterfly valve is no exception. Its shortcomings have the following two points:
1. Due to the special process of the triple eccentric butterfly valve, the structure of the butterfly plate will be relatively thick, so if a butterfly valve with a triple eccentric structure is used on a small-diameter pipeline, the resistance of the butterfly plate to the circulating medium in the pipeline will be very large in the open state, and the flow of The resistance is large, so generally speaking, the triple eccentric butterfly valve is not suitable for small diameter pipelines below DN200.
2. In the normally open pipeline, the sealing surface of the valve seat of the triple eccentric butterfly valve and all layers of the sealing ring on the butterfly plate will be washed by the front, which will affect the sealing performance of the valve for a long time.

The above is the introduction of Tanghai valve for the advantages and disadvantages of triple eccentric butterfly valve. If you have purchase requirements for triple eccentric butterfly valves, you are welcome to inquire.

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

Video of triple eccentric butterfly valve:

Structure of Triple Eccentric Metal seated Butterfly Valve (Picture)

December 31, 2021

Butterfly valves can be divided into soft-sealed butterfly valves and metal seated butterfly valves according to the sealing form. This article mainly analyzes the structure of the triple eccentric metal seated butterfly valve. Metal hard seal butterfly valves are usually used in some high temperature and high pressure environments. They are mainly composed of valve body, butterfly plate, valve shaft, valve seat, butterfly plate sealing ring, shaft sleeve, self-lubricating bearing, driving device and so on.

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

The triple eccentric metal hard seal butterfly valve is a high-performance butterfly valve. It drives the rotation of the valve shaft through various driving devices, and the valve shaft drives the butterfly plate to rotate within the range of 0-90° in the valve body passage to achieve the valve opening and closing. The purpose is to realize the control of the medium flowing in the pipeline. Because of its super high performance, the triple eccentric metal hard seal butterfly valve can be widely used in the pipelines of generators, steam, hot and cold air, chemical smelting engineering, power generation, environmental protection, etc. The applicable media include various corrosive and non-corrosive fluid media. .

Structure diagram of triple eccentric metal seated butterfly valve
Insert “154-1 Picture”

Structural features of triple eccentric metal seated butterfly valve
①Unique and novel three-way eccentric design, frictionless transmission between sealing surfaces, greatly prolonged valve life.
②The elastic seal is produced by the torque, which improves the sealing performance of the valve.
③The wedge-shaped design allows the valve to be closed tighter and tighter, realizing automatic sealing, and the sealing surfaces directly compensate each other to achieve zero leakage.
④The drive mode of the valve can be selected according to the needs of customers, such as equipped with pneumatic and electric devices.
⑤ Only need to change the material of the parts, the valve can be applied to different media, and it can also be lining anti-corrosion (lining F46, GXPP, PO, etc.).
⑥The sealing ring is made of stainless steel, and it has the advantages of metal hard seal and elastic seal. It can achieve good sealing performance regardless of low temperature environment or high temperature working conditions.

If you want to know more about the triple eccentric metal seated butterfly valve, please pay more attention to the official website of “Tanghai Valve”. If you have any valve requirements in this area, you are also welcome to inquire.

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

Video of triple eccentric butterfly valve:

Application of metal seated butterfly valve in metallurgical field

October 28, 2021

In the initial use of metallurgical blast furnaces, gate valves occupies half of the country. However, as the government has increased its efforts in environmental protection construction, and the pipe diameter of the blast

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

furnace system has gradually increased, the metal seated butterfly valve, which is light in weight, good in sealing performance, small in torque, and more suitable for making large-diameter valves, has gradually replaced gate valves. It is widely used in the field of metallurgy.
The metal hard seal butterfly valve has two driving methods: hydraulic drive and electric drive. In the ironmaking blast furnace, it is mainly installed in the waste heat utilization system, the dry dust removal system and the gas pipe network. It is used under the high temperature conditions of large nominal diameter, low working pressure and opening and closing pressure difference, and temperature of 200-350℃ . Because most of the metallurgical system pipelines are high-temperature gas media, the metal hard seal eccentric butterfly valve has been developed.
The metal hard sealing butterfly valve adopts surface-to-surface contact, and the sealing material is metal, so it is more resistant to high temperatures, even up to 400°C. However, correspondingly, the selection of metal seals has become very important. We must choose old brands and professional brands. Because brand manufacturers pay attention to reputation and their qualifications are relatively sound, we can check whether the metal seal is of high quality when purchasing, which can ensure that it maintains flexibility under high temperature conditions. This is also the possibility to ensure that the metal eccentric butterfly valve will not deform and leak after a period of use.
Now Tanghai also has a triple-eccentric butterfly valve whose sealing pair is a multi-layer composite material, which is a composite of metal and non-metal materials. This further makes up for the slight inferiority of metal sealing performance to fluorine lining, especially the non-metal interlayer in the middle can make the sealing of the sealing pair produce a stepped sealing form. After long-term use, it can still maintain good and reliable high-temperature use effects. The disadvantage is that the valve can maintain good sealing performance while maintaining high temperature and aging resistance. Various systems in metallurgical blast furnaces have been widely used, especially high-temperature systems.
Metal hard seal butterfly valves are suitable for high temperature gas pipeline systems in metallurgy, mining, cement, chemical, power generation and urban heating industries, as opening and closing equipment. In addition, Tanghai’s metal eccentric hard seal butterfly valve has compact structure, few parts, small size, light weight, high temperature resistance, flexible opening and closing, and can achieve zero leakage under long-term working conditions, long service life, and low power required. , The future will also usher in a wider range of applications.

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

Working principle and characteristics of triple eccentric butterfly valve

August 9, 2021

Triple eccentric butterfly valve, also named triple offset butterfly valve.

Nowadays, butterfly valves have been used in many industries. In the beginning, the butterfly valve was only used for the interception and communication of water media. The triple eccentric design enhances the function of the butterfly valve and has become one of the valves with excellent performance in industrial industrial pipeline equipment. The triple eccentric butterfly valve, as the name implies, is that three independent offsets are designed as valves. In reality, many people do not know which one is a triple-eccentric butterfly valve because of insufficient cognition. In this article, let’s talk about the working principle and characteristics of the triple-eccentric butterfly valve.

triple offset butterfly valve-double flange- (5)

The working principle of the triple eccentric butterfly valve is that the valve body of the butterfly valve has a horizontal valve port connected to the pipeline in structure, and the valve port has a valve plate. The shaft is perpendicular to the valve port and penetrates the valve body and the valve plate. The edge of the valve plate is provided with an outer spherical surface, and the valve port is provided with a sealing surface that can be matched with the outer spherical surface. When the sealing surface and the outer spherical surface are matched and sealed, there is an eccentric distance a between the sealing line and the axis of the shaft, which is in the transverse center of the valve plate. The line is the eccentricity b between the center line of the valve port and the center line of the shaft, and there is an angle β between the connection line of the outer spherical surface and the center line of the valve port. This is the principle of the triple eccentric butterfly valve.
The triple eccentric butterfly valve cleverly puts the triple eccentricity on the valve plate, and adopts a partial outer spherical structure on the outer edge of the valve plate. This structure needs to be completed on a CNC machine with a self-designed simple fixture. The outer eccentric spherical surface is polished to reach a roughness of Ra0.4, the spherical surface is chrome-plated or made of Stellite alloy, and the hardness reaches HRC45-60.
Put the eccentric angle on the valve plate, and press the valve seat on the valve body with a pressing ring, which solves the difficulties encountered in the processing of ordinary triple eccentric butterfly valves. The valve body, valve plate and valve seat cannot be exchanged for pairing. Repair after damage A series of problems such as high cost, all parts are modularized, warehouse management is simple, processing is simple, maintenance is convenient, and the cost of spare parts is reduced.
The butterfly valve is suitable for making large-diameter valves. It can be widely used in the cutting of petroleum transportation pipelines, metallurgical steel plants, gas main pipeline adjustment and cutting, chemical smelting equipment medium adjustment and cutting, water treatment equipment inlet and outlet adjustment and shutdown, and cooling water in thermal power stations. System, natural gas, lye, sea water, acid and other industries.

The characteristics of the triple eccentric butterfly valve are as follows:
1. Simple structure, light weight, composed of only a few parts. easy to use.
2. After the valve plate is fully opened, the thickness of the butterfly plate is the only resistance for the medium to pass through the valve body. The pressure is small and the flow can be better controlled.
3. When the valve plate is closed, the specific pressure between the outer spherical surface of the valve plate and the sealing surface of the valve seat is generated by the driving torque applied to the shaft. Coupled with the elastic compensation of the M-type elastic valve seat, the sealing performance of the valve can be enhanced, and the service life is greatly improved.
Understand the working principle and characteristics of triple eccentric butterfly valve, then where can I buy high-quality triple eccentric butterfly valve products? of course, Tanghai 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 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

Selection and application of eccentric butterfly valve

June 23, 2021

Selection and application of eccentric butterfly valve
The advantages of eccentric butterfly valves and other butterfly valves are very prominent, so they are widely used in all aspects of life and work to meet various requirements. Moreover, with the continuous development of eccentric sealing butterfly valve technology, the space for its use becomes more and more extensive. TH valve company can produce double eccentric butterfly valve and triple eccentric butterfly valves, with good quality and reasonable prices.

Double eccentric-wafer butterfly valve-D372F-150lbP-stainless steel (1)

Application of double eccentric sealing butterfly valve
The double eccentric sealing butterfly valve adopts an eccentric structure design. The main structure of the valve is composed of valve body, butterfly plate, valve seat, valve stem and transmission mechanism. The valve seat adopts a detachable structure and can be based on the physical and chemical properties of different media. Corresponding corrosion-resistant, light-resistant, and aging-resistant materials are selected, which can be widely used in fluid pipelines such as water supply and drainage, sewage, construction, air conditioning, petroleum, chemical, food, medicine, textile, papermaking, hydropower, shipbuilding, metallurgy, energy systems, etc. Used as a regulating and intercepting device. The double eccentric butterfly valve usually uses tetrafluoroethylene material as its sealing seat, and can also use metal sealing seat to expand its application in the high temperature field. However, the seal of the double eccentric butterfly valve with metal sealing seat is still a positional sealing structure, that is, the sealing surface of the butterfly plate and the seat is in line contact, so it cannot withstand high pressure, and it will inevitably lead to greater leakage when used in a high pressure system. Therefore, double eccentric butterfly valves with metal seal seats should be avoided as far as possible in high-pressure or tight shut-off systems.

Application of triple eccentric sealing butterfly valve
The triple eccentric butterfly valve, as the crystallization of the latest technology of valves, takes advantage of the advantages of various valves and avoids the shortcomings of various valves, and has attracted more and more

cryogenic triple offset butterfly valve 1

attention from users and designers. The maximum pressure level can reach 2500 pounds, the standard caliber can reach 48 inches, and the clamp, lug, flange, ring connection, butt welding, jacket, various structural lengths, etc. can be corresponded, due to the room for material selection Very large, high and low temperature, various acids, alkalis and other corrosive media can also respond freely. Especially in the aspect of large diameter, with its zero leakage advantage, it is constantly replacing the thick gate valve and ball valve in the shut-off valve. Similarly, with its excellent control function, it is also constantly replacing the bulky control valve. Shut-off valve. So far, triple eccentric sealing butterfly valves have been used in various important pipelines including China’s oil and gas exploration, offshore platforms, petroleum refining, petrochemicals, inorganic chemicals, energy power generation and other major industrial fields such as process control. In actual engineering, if the working pressure of the system is not less than 1.0 MPa or in important parts that need to be opened frequently, triple eccentric butterfly valves can be used.
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

Cryogenic valve principle |standard |illustration |selection

June 3, 2021

Principle of Cryogenic valve|Standard of Cryogenic valve|Selection of Cryogenic valve
The so-called cryogenic valve is a kind of altra-low temperature valve, as the name implies, is a valve suitable for working in cryogenic conditions. In the valve industry, valves that tend to -40°C are called cryogenic valves. Cryogenic valves are generally used in cryogenic systems such as liquid helium, liquid hydrogen, liquefied natural gas, and air separation. The medium used is liquid helium, liquid hydrogen, liquefied natural gas, liquid nitrogen, liquid oxygen and other cryogenic fluids. Under low temperature conditions, conventional metal hard seals and non-metal soft seals cannot meet the sealing requirements. In order to ensure that cryogenic valves can operate safely and reliably at low temperatures, there are some special considerations and requirements in the design and manufacture of cryogenic valves. see photo attached is a cryogenic triple offset butterfly valve.

triple offset valve parts-after-cryogenic process

Principle of ultra-low temperature valve: For valves used in ultra-low temperature conditions, the medium temperature is very low, and the metal materials will experience low temperature cold brittleness. The strength and hardness will be greatly improved, and the plasticity and toughness will be greatly reduced. This will directly affect the performance and safety of the valve. If an ordinary valve is used, the low temperature will freeze the packing in the valve stuffing box, and it will not be able to play a sealing role. In this way, the valve needs to be lengthened from the sealing seat on the bonnet to the bottom of the stuffing box. With sufficient isolation space and heat dissipation distance, the low-temperature medium in the valve body will not freeze the packing. As shown in the figure, the part marked with 175mm is the lengthened part.

In ultra-low temperature conditions, the valve stem and valve body can only adopt stuffing box or bellows structure. There are many restrictions on the use of bellows. Generally, the structure of the stuffing box seal is adopted. The stuffing box seal structure is simple to process and convenient to maintain. However, the sealing effect cannot be guaranteed under the condition of <-40℃, so the ultra-low temperature valves are all Keep the stuffing box as far away from the material as possible, and choose packing with low temperature characteristics.

Selection of ultra-low temperature valve:

cryogenic triple offset butterfly valve 1

Valve body: Ferritic stainless steel can be used when the temperature is higher than -100°C, austenitic stainless steel can be used when the temperature is lower than -100°C, copper alloy or aluminum alloy can be used for low-pressure and small-diameter valves. Stem: Made of austenitic stainless acid-resistant steel, it needs to be properly heat-treated to increase the tensile strength. At the same time, it must be hard chrome plated (coating thickness 0.04~0.06mm) or nitriding treatment to increase the surface hardness.

Gasket: When the working temperature is higher than -196℃ and the maximum low temperature working pressure is 3MPa, the asbestos rubber sheet made from long fiber can be used; when the working temperature is higher than -196℃ and the maximum low temperature working pressure is 5MPa, it can be used. Stainless steel spiral wound gasket with asbestos, stainless steel spiral wound gasket with PTFE, or stainless steel spiral wound gasket with expanded graphite.

Fasteners: when the temperature is higher than -100°C, the bolt material is Ni, Cr-Mo and other alloy steels, which need to be properly heat-treated to prevent thread bite; when the temperature is lower than -100°C, the bolt material can be austenitic Body stainless steel. The nut material is generally Mo steel or Ni steel, and the thread surface is coated with key disulfide.

Ultra-low temperature valve design standards:

1. Design: API6D, JB/T7749

2. Valve routine inspection and test: according to API598 standard.

3. Low temperature inspection and test of valve: According to JB/T7749.

4. Drive mode: manual, bevel gear drive and electric drive device.

5. Valve seat form: The valve seat adopts a welded structure, and the sealing surface is welded with cobalt-based hard alloy to ensure the sealing performance of the valve.

6. The ram adopts an elastic structure, and a pressure relief hole is designed at the pressure inlet end.

7. One-way sealing valve body is marked with flow direction mark.

8. The low-temperature ball valve, gate valve, and stop valve adopt a long neck structure to protect the packing.

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

Classification and features of Eccentric butterfly valves

July 24, 2020

Eccentric butterfly valves are divided into single eccentric butterfly valves, double eccentric butterfly valves, triple eccentric butterfly valves, and variable eccentric butterfly valves. Contrast with concentric butterfly valve. A butterfly valve whose stem axis deviates from the center of the disc and the center of the body at the same time, and the sealing pair is an oblique vertebra is called an eccentric butterfly valve.

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

Structure classification of eccentric butterfly valve:
Single eccentric butterfly valve
In order to solve the problem of the extrusion of the butterfly plate and the valve seat of the concentric butterfly valve, a single eccentric butterfly valve was produced. Its structural feature is that the shaft center of the valve stem deviates from the center of the butterfly plate, so that the lower end of the butterfly plate no longer becomes the rotation axis. Disperse and reduce the excessive squeezing between the lower end of the butterfly plate and the valve seat.
Double eccentric butterfly valve
On the basis of the single eccentric butterfly valve, the double eccentric butterfly valve is the most widely used double eccentric butterfly valve. Its structural feature is that the axis of the valve stem deviates from the center of the butterfly plate and the center of the body. The double eccentric effect enables the butterfly plate to be released from the valve seat immediately after the valve is opened, which greatly eliminates unnecessary excessive extrusion and scratching of the butterfly plate and the valve seat, reduces the opening resistance, reduces wear and improves The life of the valve seat is improved.
Triple eccentric butterfly valve
To withstand high temperatures, hard seals must be used, but the amount of leakage is large; for zero leakage, soft seals must be used, but they are not resistant to high temperatures. In order to overcome the contradiction of the double eccentric butterfly valve, the butterfly valve was eccentric for the third time. The so-called third eccentricity means that the shape of the sealing pair is not a positive cone, but an oblique cone.
Variable eccentric butterfly valve
The uniqueness of the variable eccentric butterfly valve is that the valve stem shaft where the butterfly plate is installed is a three-segment shaft structure. The three-segment shaft type valve stem has two shaft sections concentric, and the center line of the central shaft is offset 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 close to closing, the butterfly plate moves a

triple eccentric butterfly valve-lug

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.

Features of eccentric butterfly valve:

The butterfly valve and the upper and lower valve shafts are connected by special-shaped holes and special-shaped shafts. During the opening and closing process of the butterfly plate, the function of the butterfly plate floating up and down, left and right, without a pin link, reduces the interference area between the butterfly plate and the valve seat. Thereby greatly reducing the torque. The floating structure of the butterfly plate realizes the single eccentric manufacturing process and the use function of variable eccentricity.
There is an over-position stopper for the butterfly plate in the inner cavity of the valve body to ensure that the butterfly plate is not in place when it is closed.
Bushings are used between the upper and lower valve shaft holes of the valve body cavity and the upper and lower valve shaft holes of the butterfly plate to prevent large particles in the medium from entering the valve shaft holes.

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

Posts

What is the principle of triple eccentric butterfly valve

Advantages and Disadvantages of Triple Eccentric Butterfly Valves

Structure of Triple Eccentric Metal seated Butterfly Valve (Picture)

Application of metal seated butterfly valve in metallurgical field

Working principle and characteristics of triple eccentric butterfly valve

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

Selection and application of eccentric butterfly valve

Cryogenic valve principle |standard |illustration |selection

Classification and features of Eccentric butterfly valves

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