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The working principle of the ball valve (GIF)

June 23, 2021

Principle of Ball Valve (GIF), Principle of Ball Valve Working Principle

The opening and closing part of the ball valve is a sphere with a circular channel, which rotates around an axis perpendicular to the channel, and the sphere rotates with the valve stem to achieve the purpose of opening and closing the channel. The ball valve can be closed tightly with only a 90-degree rotation and a small torque. According to the requirements of the working conditions, different driving devices can be assembled to form ball valves with different control methods, such as electric ball valves, pneumatic ball valves, hydraulic ball valves, etc.
The working principle of the ball valve: When the ball valve rotates 90 degrees, the inlet and outlet should all show a spherical surface, thereby closing the valve and cutting off the flow of the medium.

ball valve working diagram-3D GIF animated presentation

When the ball valve rotates 90 degrees, all the ball ports should be present at the inlet and outlet, so as to open the flow, and there is basically no flow resistance.
The structure principle of the ball valve:
1. The ball valve is not restricted by the installation direction, and the flow direction of the medium can be arbitrary. The fluid resistance is small, and the full-bore ball valve basically has no flow resistance.
2. The ball valve has a simple structure, relatively small size, light weight and easy maintenance.
3. Close and reliable. It has two sealing surfaces, and the current sealing surface materials of ball valves are widely used in various plastics, which have good sealing performance and can achieve complete sealing. It has also been widely used in vacuum systems.
4. The ball valve is suitable for frequent operation, opening and closing quickly and lightly. It is easy to operate and open and close quickly. It only needs to rotate 90° from fully open to fully closed, which is convenient for remote control.

ball valve (4)

5. The maintenance is convenient, the structure of the ball valve is simple, the sealing ring is generally movable, and it is convenient to disassemble and replace.
6. The ball valve has good sealing performance. When fully open or fully closed, the sealing surface of the ball and the valve seat is isolated from the medium, and the medium will not cause erosion of the valve sealing surface when the medium passes.
7. It has a wide range of applications, with a diameter ranging from a few millimeters to a few meters, and can be applied from high vacuum to high pressure.
8. Since the ball valve has wiping properties during opening and closing, it can be used in media with suspended solid particles.
9. The ball valve has low fluid resistance, no vibration, and low noise.

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

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

full bore ball valve vs reduced bore ball valve

June 22, 2021

The difference and selection of full bore ball valve and reduced bore ball valve
Ball valve is currently the most widely used mechanical product in all valve markets. It is mainly composed of valve body, valve seat, ball, valve stem and transmission device. The ball core is driven to rotate through the actuator to achieve the function of switching or adjusting. . In the chemical industry, environmental protection, water treatment, urban construction, machinery, and food industries, it is widely used and very popular! there are Electric ball valve and Pneumatic ball valve, and other actuated ball valves.

Pneumatic electric high platform ball valve

There are many types of ball valves, which can be combined into various products with different functions through different structures, connection methods, pressure levels, drive forms, etc., but from the most basic point of view, ball valves have two types: full-diameter ball valves and reduced-diameter ball valves. The difference between major categories. Generally speaking, when the inner diameter of the valve ball is less than or equal to 85% of the inner diameter of the ball valve port, it is called a reduced-diameter ball valve, and when the inner diameter of the ball valve is greater than 95% of the inner diameter of the ball valve port, it is called a full-bore ball valve. So what is the difference between the two in the selection or application?
The definition of full bore ball valve and reduced bore ball valve:

fixed ball valve

1. The full-bore ball valve has equal-width flow channels, that is to say, the size of the orifices from inflow to outflow is the same, and its size cannot be less than the value specified by the standard, which is roughly equivalent to the nominal diameter of the specification, such as DN50 full-diameter The diameter of the ball valve flow path also needs to be about 50;
2. The inlet of the reduced diameter ball valve is wider than the diameter of the flow path, and the actual diameter of the flow path is about one specification smaller than this specification. For example, the diameter of the DN50 reduced diameter ball valve is about 38, which is roughly equivalent to the specification of DN40. One specification is reduced within DN250 and two specifications are reduced from 250-600. Above 600 depends on the actual situation.
Applicable medium for full bore ball valve and reduced bore ball valve:
1. The full-bore ball valve is generally used on pipelines for conveying viscous and slagging media. Because of its low fluid resistance, it can be said that there is basically no flow resistance, and it is convenient for regular wax scrapers to pass through.
2. Reduced diameter ball valve is suitable for conveying gas or pipelines with physical properties similar to water. Because its weight is about 30% lighter than a full-diameter ball valve, and its flow resistance is only 1/7 of that of a stop valve of the same diameter. about. It is helpful to reduce the pipeline load and reduce the cost.
Applicable process for full bore ball valve and reduced bore ball valve:
1. For pipelines that require regular pigging, no matter what kind of medium is transported, full-diameter ball valves must be used. The medium passing through the full-bore ball valve will not reduce the flow, and the flow resistance is small, which is an ideal product for pipeline control, especially for strict working conditions. Especially when the main line in the oil pipeline and gas pipeline needs to be buried underground, full-diameter welded ball valves must be used.
2. The reduced diameter ball valve is suitable for some working conditions such as low requirements and small convection resistance requirements. When the inner diameter of the valve is greater than 80% of the inner diameter of the pipe end, it has almost no effect on the pipeline fluid passing capacity. Many valves have a reduced diameter, which is generally controlled within 0.8. On the one hand, the reduced diameter reduces the flow capacity of the valve, that is, the Kv value of the valve, and increases the pressure drop at both ends of the valve, causing energy loss. That said, there is not much impact, and it may increase the erosion of the pipeline.
The advantages and disadvantages of full-bore ball valves and reduced-bore ball valves are compared:
1. Installation space: The reduced-diameter ball valve has a small volume, so its installation space requirements are smaller. Because its weight is about 30% lighter than a full-diameter ball valve, it is beneficial to reduce the pipeline load, reduce the transportation load and reduce the cost.
2. Cost: Reduced-diameter ball valves are one grade lower than full-diameter ball valves. Considering the cost performance, it is generally accepted internationally that adjacent pipe diameters use the same ball-diameter valve body. For example, dn32 and dn40, dn50 and dn63, dn90 and dn110, dn160 and dn200, dn250 and dn315 use the same sphere.
Note: Since the inner diameter of the reduced diameter ball valve is small, the torque on the valve stem is small, which is more suitable for prolonging the service life of the valve switch. Especially the low-torque design of large-diameter valves. However, the diameter cannot be reduced too much, otherwise the system resistance will increase. However, if the diameter is not reduced, the purchase cost will be increased, and the control characteristics of the valve will generally be reduced, which will make the adjustment effect worse. For example, if the regulating valve is always used at a small opening, the service life of the valve will be reduced.

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

Application of low temperature butterfly valve

June 22, 2021

Article title: Application of low temperature triple eccentric butterfly valve
With the rapid development of industrial technology, more stringent requirements have been put forward for valves, especially for butterfly valves used in low temperature media. In addition to meeting the performance of general valves, it is more important that butterfly valves seal under low temperature conditions. Reliability, flexibility of action and some other special requirements for cryogenic valves. Now combined with its structural characteristics, a brief introduction to the performance of the cryogenic butterfly valve is given. Remarks: The cryogenic butterfly valve we are talking about here specifically refers to the low temperature triple eccentric butterfly valve.

triple offset valve parts-after-cryogenic process

Requirements for sealing performance of low temperature triple eccentric butterfly valve:
There are two main reasons for the leakage of the low temperature triple eccentric butterfly valve, one is internal leakage; the other is external leakage.
1. Internal leakage of butterfly valve:
The main reason for the internal leakage of the valve is the deformation of the sealing pair in the low temperature state. When the temperature of the medium drops to a phase change of the material, the volume changes, which causes the sealing surface with high grinding accuracy to warp and deform, resulting in poor low-temperature sealing. We conducted a low temperature test on the DN250 valve. The medium was liquid nitrogen (-196 ℃) and the butterfly plate material was 1Cr18Ni9Ti (without low temperature treatment). It was found that the sealing surface warped and deformed up to about

cryogenic triple offset butterfly valve 1

0.12mm, which is the main cause of internal leakage. And if the plane seal of the butterfly valve is changed to a cone seal. The valve seat is an oblique cone ellipse sealing surface, which forms a sealing pair with a round elastic sealing ring embedded on the butterfly plate. The sealing ring can float radially in the butterfly plate groove. When the valve is closed, the elastic sealing ring first contacts the short axis of the elliptical sealing surface. As the valve stem rotates, the sealing ring is gradually pushed inward, forcing the elastic ring to contact the long axis of the oblique cone surface, and finally the elastic sealing ring All contact with the oval sealing surface. Its sealing is achieved by the deformation of the elastic ring. Therefore, when the valve body or butterfly plate is deformed at low temperature, it will be absorbed and compensated by the elastic sealing ring, and leakage and jamming will not occur. When the valve is opened, this elastic deformation disappears immediately, and there is basically no relative friction during the opening and closing process, so the service life is long.
2. Leakage of butterfly valve:
One is that when the valve and the pipeline are connected by flanges, leakage occurs due to the unsynchronized contraction and relaxation of the connecting gasket, connecting bolts, and connecting materials at low temperatures. Therefore, we changed the connection between the valve body and the pipeline from a flange connection to a welded structure to avoid low temperature leakage. The second is leakage at the valve stem and packing. Generally, most valve packing adopts F4 because of its good self-sliding performance, low friction coefficient (friction coefficient for steel f=0.05 ~ 0.1), and unique chemical stability, so it is widely used. However, F4 also has shortcomings. First, the tendency of cold flow is large; second, the linear expansion coefficient is large, and the cold shrinkage at low temperature causes leakage, which causes a large amount of ice at the valve stem, so that the valve fails to open. The low-temperature triple-eccentric butterfly valve developed for this purpose adopts a self-shrinking sealing structure, that is, taking advantage of the large expansion coefficient of F4, and achieves the purpose of sealing at room temperature and low temperature through the reserved gap.
Design requirements for low temperature triple eccentric butterfly valve body and stem bushing:
1. The structure and shape of the cryogenic valve shell. The correct selection of materials is of great significance to the normal and reliable operation of the valve. Compared with the stop valve and gate valve, the structural characteristics of the butterfly valve not only avoid the irregular shape and uneven shell wall thickness, which can cause problems at low temperatures. Due to the small size of the butterfly valve, the shape of the valve body is basically symmetrical, so the heat capacity is small; the pre-cooling consumption is also small; the shape is regular and it is convenient to take measures to keep the valve cold. ,
2. Selection of stem bushing: Some low-temperature triple-eccentric butterfly valves are in operation, the rotating parts of the valve are sticky, and seizure occurs from time to time. The main reason is: unreasonable selection of matching materials, too small pre-cooling clearance, and processing Causes such as low accuracy. In the development of cryogenic valves, a series of measures have been taken to prevent the occurrence of the above phenomena. For the upper and lower bushings of the valve stem, SF-1 type composite bearings with low friction coefficient and self-lubricating properties are selected, which can be suitable for some special needs of cryogenic valves. The metal-sealed butterfly valve has the characteristics that some ordinary valves do not have, especially the small flow resistance, reliable sealing, rapid opening and closing, and long service life. The triple eccentric metal sealing butterfly valve is sealed by the deformation of the elastic ring, so it does not need to rely on the force of the medium, so it can be used for two-way sealing.
Related information: The difference of cryogenic valve and ordinary temperature valve; Cryogenic valve principle |standard |illustration |selection

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

Fire-proof and anti-static ball valve and ordinary ball valve

June 18, 2021

The difference and selection of fire-proof and anti-static ball valve and ordinary ball valve
The fire-proof and anti-static ball valve is a kind of pipeline that can be used for natural gas, artificial coal gas, liquefied gas, city gas and non-corrosive gas. It has anti-static and fire-proof devices, that is, it is installed between

fixed ball valve

the ball and the valve stem, the valve stem and the valve body. The conductive spring enables the static electricity generated in the opening process of the valve to be introduced into the underground through the set static electricity channel, so as to achieve the purpose of eliminating static electricity. Avoid static sparking and ignite flammable media to ensure system safety. The fire protection device, that is, the ball valve is designed with double seals. When the soft gasket melts due to high temperature, the valve core ball is again designed to form a right-angle hard seal with the soft seal behind, forming a sealing relationship again.
The fire-proof anti-static ball valve is compared with the conventional ordinary ball valve. It will be widely used in many industries, and its safety performance has been improved a lot. For occasions prone to fire, it can effectively prevent internal leakage. The realization of this function mainly depends on the ball valve. Sealing ring, this kind of sealing ring is a double-layer seal, a layer of soft seal and a layer of metal seal, when the soft seal layer is destroyed by combustion, the metal seal can further fill the air, play a key alternate sealing role, can be to a certain extent It prevents a large amount of media from leaking out and the spread of fire.

electric ball valve

When the fire-proof and anti-static ball valve is switched, there will be friction between the ball and the valve seat, and the static electricity generated by the friction will accumulate on the ball. This is not allowed for the ball valves used on the gas, fuel, and chemical pipelines. , It may cause pipeline explosion accidents. The anti-static structure of the ball valve is equipped with an electrostatic discharge device, which can extract the electrostatic charge gathered in the sphere in the first time, effectively ensuring the safe operation of the pipeline; generally, elastic components are usually used at home and abroad According to the standard, the connection between the ball and the valve body and the valve stem and the ball is below 12VDC, and the resistance value is below 10 ohms.
It should be noted that the fire and anti-static functions of ball valves are not omnipotent. They can only play an emergency role and give more time to solve accidents. In addition to the use of fire-resistant and anti-static ball valves in gas and oil pipelines, they also It should be equipped with certain fire-fighting measures such as explosion-proof and fire-prevention, and strictly abide by relevant national regulations.

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 hard seal butterfly valve vs electric soft seal butterfly valve

June 18, 2021

The difference between electric hard seal butterfly valve and electric soft seal butterfly valve
With the rapid development of many industrial fields in our country, industrial automation has gradually replaced the manual operating system, especially the use of various automatic control valves. With its unique structural

wafer type butterfly valve, EPDM seat (10)

characteristics, electric butterfly valves have become one of the most used valve types. First, the scope of application is also the most extensive. However, in different working conditions, it is particularly important to choose different electric butterfly valves, not to waste costs, and to save resources. From the valve sealing structure, electric butterfly valves can be divided into two categories: soft seal and hard seal. What is the difference between them? Which one has more advantages? How should we distinguish between them?

The difference between the electric hard-sealed butterfly valve and the electric soft-sealed butterfly valve is mainly reflected in the performance and structure. The two seals can complement each other. Both have advantages and disadvantages. The advantage of one side may be the disadvantage of the other. When choosing, you should analyze your own needs, working conditions, etc., and choose the right product.
The main differences are as follows:
1. From the structure: the electric soft sealing butterfly valve is mostly in the middle line structure, and the sealing material is generally fluorine plastic, rubber, resin, etc., which has good corrosion resistance and sealing. Choose different parts and materials, which can be suitable for use. In a variety of media. Electric hard-sealed butterfly valves are mostly single-eccentric, double-eccentric and triple-eccentric butterfly valves. The seals are mostly stainless steel + cemented carbide. Among them, the three-eccentric butterfly valve has no friction transmission between the sealing surfaces, and has the characteristics of high temperature resistance, wear resistance, and good mechanical properties.

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

2. Temperature resistance: soft seal is used in normal temperature environment, hard seal can be used in low temperature, normal temperature, high temperature and other environments;
3. In terms of pressure: soft seal low pressure-normal pressure, hard seal can also be used in working conditions such as medium and high pressure;
4. Sealing performance: The soft sealing butterfly valve has better sealing performance and can reach zero leakage. The disadvantage is that it is easy to age, wear, and has a short service life. The hard-sealed butterfly valve can maintain good operation under high pressure and high temperature, is relatively resistant to wear, has good mechanical properties, and has a long service life, but the sealing performance is poor!
When the electric butterfly valve is opened and closed, it not only saves effort, but also has low flow resistance. It is convenient and quick to operate, light in weight, small in size, and has a relatively simple structure. Customers can choose a soft-seal or hard-seal butterfly valve reasonably according to economic conditions, the conditions of the medium used, and the on-site environment.

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

High platform ball valve and ordinary ball valve

June 17, 2021

The difference and selection of high platform ball valve and ordinary ball valve
High platform ball valve, the so-called high platform means that the ball valve adopts the ISO5211 manufacturing standard. A square or round flange and the ball valve are cast into one piece, and the end of the platform is higher than the outer edges of the flanges at both ends, which is not only conducive to easy installation Pneumatic actuators, electric actuators and other actuators can greatly improve the stability between the valve and the actuator, and the appearance is more beautiful and refined. The high platform usually called york or bracket.

Pneumatic electric high platform ball valve

Electric high platform ball valve Pneumatic high platform ball valve
The high platform ball valve is an evolution of the conventional ordinary bracket ball valve. The difference between it and the ordinary ball valve is that it can be directly connected to the drive actuator without installing a connecting bracket, while the ordinary ball valve requires the bracket to be installed before the actuator can be installed. . In addition to avoiding additional bracket installation, because it is installed directly on the platform, this greatly improves the stability between the actuator and the ball valve.
The advantage of the high platform ball valve is that it can directly install pneumatic or electric actuators on its own platform, while ordinary ball valves require additional valve connections. This may occur due to loose brackets or excessive coupling gaps. As a result, the valve is affected in use, but the high platform ball valve will not have this problem. Its performance is very stable during operation.

Schematic diagram of high platform ball valve

In the selection of high-platform ball valves and ordinary ball valves, the internal structure of the high-platform ball valve is still the principle of opening and closing, which is consistent with the ordinary ball valve. In addition to the advantages described above, when the medium temperature is relatively high, it needs to be adopted The connection bracket is to protect the normal use of the actuator and prevent the heat transfer of the medium from causing the actuator to be unusable.

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

Vulcanized vs soft seated/back-up butterfly valve

June 17, 2021

The difference between rubber-lined butterfly valve and rubber butterfly valve (illustration)
The difference between a rubber-lined butterfly valve and a rubber butterfly valve, and the difference between a rubber-lined butterfly valve and a plastic-lined butterfly valve. The rubber-lined butterfly valve uses a high-temperature method to vulcanize the rubber and the valve body into one body. It has very high corrosion resistance and is generally used. To control some corrosive fluids with strong acidity and alkalinity. The rubber butterfly valve is a butterfly valve whose seal is a rubber seal, which is generally called a valve seat, and is separately installed into a whole.

Fluorine lined butterfly valve-PTFE-WAFER (8)

At normal temperature, the abrasion resistance of natural soft rubber is much better than that of nitrile rubber, but their high temperature resistance is the highest limit within 80 degrees, and it is not suitable for use if it exceeds.
The difference between a fully lined butterfly valve and a half lined butterfly valve:
1. Semi-lined butterfly valve means: the butterfly valve is not lined with rubber, but the place where the butterfly valve is connected to the valve body is lined with rubber;
2. Fully lined butterfly valve means: the butterfly plate of the butterfly valve and the part connected with the valve body are lined with rubber. The difference between rubber-lined butterfly valve, fluorine-lined butterfly valve and plastic-lined butterfly valve: rubber-lined butterfly valve and fluorine-lined butterfly valve are only one kind of plastic-lined butterfly valve.

wafer type butterfly valve (6)

The sealing materials in the rubber-lined butterfly valve are:
Applicable temperature of hard rubber NR: -10℃~85℃,
Applicable temperature of soft rubber BR: -10℃~85℃,
Suitable temperature for butyl rubber IIR: -10℃~120℃,
Applicable temperature of neoprene CR: -10℃~105℃;
The sealing materials in the fluorine-lined butterfly valve are:
Use temperature of polyperfluoroethylene FEP (F46): -85℃~150℃,
Polytetrachloroethylene PTFE (F4) operating temperature: -200℃~180℃,
Polytrifluoroethylene PCTEF (F3) operating temperature: -195℃~120℃,
Polypropylene: RPP operating temperature: -14℃~80℃,
Polyvinyl chloride: rigid) PVC service temperature: 0℃-55℃,
Polyvinylidene chloride PVDF (F2) operating temperature: -70℃~100℃,
Polyolefin: PO Operating temperature: -58℃~80℃.

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

Prevention and treatment of valve corrosion

June 16, 2021

What is valve corrosion?
Corrosion of the valve is usually understood as the damage to the metal material of the valve under the action of a chemical or electrochemical environment. Since the “corrosion” phenomenon occurs in the spontaneous interaction between the metal and the surrounding environment, how to isolate the metal from the surrounding environment or use more non-metallic synthetic materials is the focus of corrosion prevention. The valve body (including the bonnet) of the valve occupies most of the weight of the valve and is in constant contact with the medium. Therefore, the selection of the valve is often based on the material of the valve body.

Fluorine lined butterfly valve-PTFE-WAFER (8)

The corrosion of the valve body is nothing more than two forms, namely chemical corrosion and electrochemical corrosion. Its corrosion rate depends on the temperature, pressure, chemical properties of the medium and the corrosion resistance of the valve body material. The corrosion rate can be divided into six levels:
1. Complete corrosion resistance: the corrosion rate is less than 0.001 mm/year;
2. Extremely resistant to corrosion: the corrosion rate is 0.001 to 0.01 mm/year;
3. Corrosion resistance: the corrosion rate is 0.01 to 0.1 mm/year;
4. Still corrosion resistant: the corrosion rate is 0.1 to 1.0 mm/year;
5. Poor corrosion resistance: the corrosion rate is 1.0 to 10 mm/year;
6. Not resistant to corrosion: the corrosion rate is greater than 10 mm/year.

How to prevent valve corrosion?
The anti-corrosion of the valve body is mainly based on the correct selection of materials. Although there are abundant anti-corrosion materials, it is not easy to choose the right one, because the problem of corrosion is very complicated. For example, sulfuric acid is very corrosive to steel when the concentration is low, and when the concentration is high, the steel is produced. Passivation film can prevent corrosion; hydrogen only shows strong corrosiveness to steel under high temperature and high pressure. The corrosion performance of chlorine is not great when it is in a dry state, but it is very corrosive when there is a certain humidity, and many materials cannot be used. . The difficulty in selecting valve body materials lies in not only considering corrosion issues, but also factors such as pressure resistance and temperature resistance, whether it is economically reasonable, and whether it is easy to purchase. So it must be attentive.
1. The second is to take lining measures, such as lining lead, lining aluminum, lining engineering plastics, lining natural rubber and various synthetic rubbers. If the media conditions permit, this is an economical method.
Second, again, when the pressure and temperature are not high, the main material of the fluorine-lined valve can often be very effective in preventing corrosion.
3. In addition, the outer surface of the valve body is also corroded by the atmosphere, and generally steel materials are protected by painting.

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 working principle of butterfly valve (picture)

June 15, 2021

Working principle of butterfly valve:
The butterfly valve is a valve that opens and closes according to the rotation of the valve stem, while driving the disc plate to rotate. In the cylindrical channel of the butterfly valve body, the disc-shaped butterfly plate rotates around the axis, mainly by rotating the disc plate 90° for flow control. When the disc reaches 90°, the valve is in a fully open state, and the angle of the disc can be changed to adjust the medium flow. It is generally installed in the

U-type-flange-butterfly-valve-2

diameter direction of the pipe. The butterfly valve and the valve stem have no locking ability. In order to effectively adjust the flow, a worm gear reducer is required. The butterfly valve with a worm gear reducer not only makes the butterfly valve self-locking, but also changes the operating performance of the butterfly valve and adjusts the medium flow more accurately. .
Features of butterfly valve:
(1) Simple structure and small size. Due to its compact structure, short structure length, small size and light weight, it is suitable for large diameters.
(2) The fluid resistance is small. When fully opened, the effective flow area of the valve seat channel is large, so the fluid resistance is small.
(3) The opening and closing is convenient and rapid, the adjustment performance is good, and the butterfly plate rotates 90. Both can complete the opening and closing. The flow can be controlled in stages by changing the rotation angle of the butterfly plate.

(4) The opening and closing moment is small, because the discs on both sides of the rotating shaft are basically the same under the action of the medium, and the direction of the torque is opposite, so the opening and closing is labor-saving.
(5) The low-pressure sealing performance is good, and the sealing surface material is generally rubber or plastic, so the sealing performance is good. Limited by the material of the sealing ring, the operating pressure and operating temperature range of the butterfly valve is relatively small. However, the working pressure and working temperature range of the hard seal butterfly valve have been greatly improved.

butterfly valve working diagram-3D GIF animated presentation

1. The butterfly valve has a small flow resistance when it is fully opened. When the opening is between about 15° and 70°, it can carry out sensitive flow control. Therefore, the application of butterfly valves is very common in the field of large-diameter adjustment. Since the movement of the butterfly plate of the butterfly valve is wiping, most butterfly valves can be used for media with suspended solid particles. Depending on the strength of the seal, it can also be used for powder and granular media.
2. The butterfly valve is suitable for flow adjustment. Because the pressure loss of the butterfly valve in the pipe is relatively large, about three times that of the gate valve, when selecting the butterfly valve, the influence of the pressure loss of the piping system should be fully considered, and the strength of the butterfly plate to withstand the pressure of the pipeline medium when it is closed should also be considered. . In addition, it is necessary to consider the limitation of the working temperature that the elastic valve seat material can withstand at high temperatures. To
3. The structural length and overall height of the butterfly valve are small, the opening and closing speed is faster, and it has good fluid control characteristics. The structure principle of butterfly valve is most suitable for making large-diameter valves. When a butterfly valve is required to control flow, the most important thing is to correctly select the specification and type of the butterfly valve so that it can work properly and effectively.
Related knowledge: Principles of butterfly valve structure
Related products: Electric switching butterfly valve Electric regulating 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

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