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Factors Affecting the Operation and Use of resilient seated Butterfly Valves

August 18, 2021

Butterfly valves are classified according to the sealing material, which can be divided into resilient seated butterfly valves and hard-sealed butterfly valves. There is a big difference in the scope of use between the two. The sealing pair of the resilient seated butterfly valve is composed of two parts. One side of the sealing pair is made of metal hard

U-type-flange-butterfly-valve-2

material and the other side is non-metal soft material. This combination makes the resilient seated butterfly valve have good sealing performance and can achieve zero leakage. However, compared with hard-sealed butterfly valves, resilient seated butterfly valves are not suitable for high temperature environments.

The resilient seated butterfly valve is small in size, light in weight, and has good sealing performance. It is responsible for switching on and off and controlling fluid flow in the pipeline system. It has a very wide range of applications in petroleum, chemical, metallurgical, and municipal construction industries.

The connection method of resilient seated butterfly valve is flange type and wafer type. In the process of operating and using resilient seated butterfly valve, some situations are often encountered. Let’s take a look at the factors that affect the operation and use of resilient seated butterfly valve.

In the valve market, rubber and PTFE are the most commonly used sealing materials for resilient seated butterfly valves. These sealing materials can maximize the sealing performance of resilient seatedbutterfly valves, regardless of whether it is a liquid or a gas medium. Zero leakage. However, because of the limitations of the structural characteristics of these sealing materials, the resilient seated butterfly valve cannot be used in high temperature, high pressure and high-wear circulation pipelines. If any of the above conditions appears in the pipeline, the resilient seated butterfly valve will malfunction and damage.
Fluorine lined butterfly valve-PTFE-WAFER (10)
The sealing ring of the resilient seated butterfly valve is fixed on the valve plate. When the butterfly plate of the butterfly valve is in the open position, the fluid medium in the pipeline will flush the sealing surface of the butterfly valve positively. Under the long-term erosion and corrosion of the fluid medium, the resilient seated material will wear out over time, which will affect the sealing performance of the resilient seated butterfly valve and cause leakage.

The factors that affect the operation of the resilient seated butterfly valve are the above two points. After the operator understands this information, he must pay attention to the use of the resilient seated butterfly valve, master the correct operation method of the resilient seated butterfly valve, and regularly perform maintenance and repairs to maximize the resilient seated butterfly valve Play a role and serve our industrial production.

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

Applicable occasions and application conditions of butterfly valves

August 17, 2021

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

U-type-flange-butterfly-valve-2

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

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

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

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

TH Valve is a professional manufacturer of butterfly 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

Introduction to basic knowledge of gate valve

August 16, 2021

The gate valve is one of the important pipe fittings in the pipeline for conveying fluid media. The gate valve is mainly used for cutting off the medium. It can only be fully opened or fully opened, and cannot be used for flow adjustment. Its opening and closing part is a gate. The movement direction of the gate is perpendicular to the direction of the fluid. The gate has two sealing surfaces. When the gate valve is closed, the sealing surface of the gate can be pressed to the other side only by the pressure of the medium. The valve seat is sealed, which is self-sealing. Most gate valves are forcibly sealed, that is, when the valve is closed, it needs to rely on the external force of the medium to force the gate to the valve seat to ensure the tightness of the sealing surface.

BS5163-BB-NRS-soft seated-wedge gate valve-DN200-PN16-handwheel (1)nt

The gate valve has a wide range of uses, and has applications in petroleum, petrochemical, chemical, metallurgical, electric power, water conservancy, urban construction, fire protection, coal and other industries. Gate valve is also a valve with distinct advantages and disadvantages.

Advantages of gate valve
1. After the gate valve is opened, the medium channel inside the valve body is straight, without any obstruction, and the flow resistance is very small.
2. When opening and closing, the movement direction of the gate valve is perpendicular to the flow direction of the medium, the pressure is small, and the opening and closing is labor-saving.
3. The height of the gate valve is large, so the opening and closing time is longer, and water hammer is not easy to occur.
4. The two sides of the gate valve channel are symmetrical, and the medium can flow in any direction on both sides, so the installation of the gate valve is very convenient.
5. The length of the structure is short, the manufacturing process is good, and the scope of application is wide.

Disadvantages of gate valve
1. The sealing surface of the gate valve is very easy to wear, which affects the service life of the valve, and it is troublesome to maintain.
2. The structure of the gate valve is more complicated, and it is also troublesome to process, especially the sealing surface on the gate seat is not easy to process, and there are many parts, so the price is more expensive.
3. The overall size is large, a certain amount of space is required for opening, and the opening and closing time is long.

Precautions for installation and use of gate valve
1. Handwheels, handles and transmission mechanisms are not allowed to be used for lifting, and collisions are strictly prohibited.
2. The double sluice gate valve should be installed vertically, that is, with the hand wheel facing upwards.
3. The gate valve with bypass valve should be opened before opening, the purpose is to balance the pressure difference between the inlet and outlet.
4. The gate valve with transmission mechanism should be installed strictly in accordance with the product manual.
5. If the gate valve is switched frequently, lubricate at least once a month.
6. The gate valve is not suitable for regulating or throttling.

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

Installation and Maintenance of Butterfly Valve

August 13, 2021

The butterfly valve has become one of the most widely used valves. Although it is only a small part on the fluid pipeline, it has a very large effect. The installation and maintenance of butterfly valves is a science. The correct installation of butterfly valves is the first step to ensure the normal operation of the pipeline, and subsequent maintenance has a positive effect on prolonging the service life of butterfly valves and reducing production costs. This article will talk about the installation and maintenance of butterfly valves for you.

lug type butterfly valve, ductile iron, center lined,

The working principle of butterfly valve
The working principle of the butterfly valve is that the valve stem drives the rotation of the butterfly plate to complete the opening and closing, and the rotation angle is 90°; changing the deflection angle of the butterfly plate can control the flow of the medium. Common butterfly valves include wafer butterfly valves and flange butterfly valves. Wafer type butterfly valve uses double-head bolts to connect the valve between two pipeline flanges. Flange type butterfly valve has flanges on the valve, and bolts are used to connect the flanges at both ends of the valve to the pipeline flanges. Butterfly valve allows fluid speed: liquid ≤ 4.5 m/s, gas ≤ 20 m/s.

Installation direction and position of butterfly valve

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

Butterfly valves generally have no direction requirements. If required, it should be determined according to the rotation angle of the butterfly valve and the working principle of the pneumatic actuator. The best position of the valve installed on the horizontal pipeline is vertical installation, and vertical downward is not allowed. The valve installation position must be easy to operate; timely installation is temporarily difficult, and the operator must also consider the long-term work of the operator. It is best to keep the valve hand wheel flush with the chest, generally 1.2 meters away from the operating floor, so that it is easier to open and close the valve. The handwheel of the floor valve should be upward, not tilted. For valves that lean against the wall against the equipment, leave room for the operator to stand on. It is necessary to avoid operating from the sky, especially acid-base, toxic media, etc., otherwise it is very unsafe.

Maintenance work of butterfly valve
When maintaining the butterfly valve, pay attention to whether there is water in the pneumatic actuator mechanism. In the wet season, the accumulation of water in the air compressor tank makes the transmission mechanism or the transmission shaft sleeve rust, and the accumulation of water in the air compressor tank in the cold winter weather enters the pneumatic actuator mechanism and freezes, causing aerodynamics. When the actuator is operated, the torque is too large, which damages the transmission components and cannot be operated manually; if the actuator is operated forcibly, the internal parts of the actuator will also be damaged. During maintenance, the discharge valve in the air compressor tank should be opened from time to time and the internal water should be taken out. For butterfly valves with hand wheels, open the turbine box cover to check whether the lubricating oil is normal within 6 months of operation, and keep a proper amount of lubricating oil.

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

resilient seated butterfly valve vs metal seated butterfly valve

August 12, 2021

Butterfly valve, also called flap valve, has a wide range of uses. It is generally installed on pipelines that transport various corrosive and non-corrosive fluid media in gas, natural gas, liquefied petroleum gas, cold and hot air, chemical smelting and other engineering systems for adjustment. And cut off the flow of the medium. There are many types of butterfly valves, and different types of butterfly valves have different uses. Butterfly valves are classified according to the sealing form and can be divided into soft-sealed /resilient seated butterfly valves and hard-sealed /metal seated butterfly valves. Although there is only one word difference between the two types of butterfly valves, they are very different in terms of structural materials and application fields. This article will analyze the difference between a resilient seated butterfly valve and a metal seated butterfly valve.

wafer type butterfly valve, EPDM seat (10)

The main difference between resilient seated butterfly valve and metal seated butterfly valve lies in the sealing surface:

The two sides of the sealing pair of the resilient seated butterfly valve are made of metal materials on one side, and the other side is made of elastic non-metallic materials, generally rubber or tetrafluoroplastics. The combination of this sealing material makes the resilient seated butterfly valve have good sealing performance, but it is not resistant to high temperature, easy to wear, and has a short service life.

Both sides of the sealing pair of the metal seated butterfly valve are made of metal materials. The metal-to-metal seal makes the sealing performance of the metal seated butterfly valve normal, but it is resistant to high temperature, pressure and abrasion, and has a long service life.

The seat of the soft sealing butterfly valve is made of rubber or tetrafluoroplastic. It has excellent sealing performance and can achieve zero leakage, but it has a relatively short service life and is not resistant to high temperatures. It is also not suitable for some highly corrosive media pipelines. The sealing seat of the hard-sealed butterfly valve is made of metal material, and the sealing performance is

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

relatively poor, but it is wear-resistant and has strong pressure resistance. It is suitable for strong corrosive medium pipelines.

In addition to the difference in the sealing surface, the difference between the resilient seated butterfly valve and the metal seated butterfly valve is as follows:

Resilient seatedbutterfly valves are mostly center-line type. Metal seatedbutterfly valves are mostly single eccentric, double eccentric and triple eccentric.
The Resilient seatedbutterfly valve is suitable for normal temperature environment. metal seatedbutterfly valves are well adapted to low temperature, normal temperature and high temperature environments.
The Resilient seatedbutterfly valve is suitable for low pressure and normal pressure environment. metal seated butterfly valveis not only suitable for low pressure and normal pressure, but also suitable for medium and high pressure working environment.
As mentioned above, the sealing performance of the Resilient seatedbutterfly valve is better than that of the metal seatedbutterfly valve, but now in order to adapt the hard sealing butterfly valve to more working conditions, it has a special process
The Resilient seatedbutterfly valve is suitable for the two-way opening and closing of the ventilation and dust removal pipeline and the adjustment of water treatment, light industry, petroleum, chemical and other industries. metal seatedbutterfly valves are mostly used in heating, gas, gas, oil, acid and alkali environments.

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

Difference between NRS gate valve and RS gate valve

August 11, 2021

NRS gate valve, means Non-rising Stem gate valve; RS gate valve, means Rising stem gate valve. you can see the difference in appearance on below photos.

Gate valve is one of the most common valves in piping systems. Because it can only be fully open and fully open, gate valves are commonly used when the fluid medium in the pipeline needs to be cut off. The operation of the gate valve does not need to be so frequent. Gate valves are widely used because they can be divided into many types. Different gate valve types have certain differences in use. This article mainly analyzes the difference between the RS gate valve and the NRS gate valve.

rising stem gate valve-RS-BB OS&Y (3)

Gate valves are classified according to the type of stem, which can be divided into two types: RS gate valve and NRS gate valve. The two are different in transmission mode, valve body structure, installation space, application range, etc.
1. The difference in the transmission mode. The transmission mode of the RS gate valve is that the handwheel drives the nut to rotate in place, and the valve stem rises and falls linearly. Through the threaded drive of the valve stem and the steering wheel, the valve flap is raised and lowered to complete the switch; the NRS gate valve is manual The wheel drives the valve stem to rotate. The hand wheel and the valve stem are connected together and relatively immovable. There are threads in the gate, and the valve stem rotates at a fixed point to drive the gate to rise and fall.
Second, the difference in structure, the structure of the rising stem gate valve is that the stem nut is on the bonnet or bracket. When the gate is opened and closed, the stem nut is rotated to realize the lifting of the stem. The structure of the NRS gate valve is that the stem nut is in the valve body and is in direct contact with the medium; when opening and closing the gate, it is realized by rotating the stem.

DIN-F4-BB-NRS-soft seated-wedge gate valve-DN100-PN16-copper holding ring-handwheel (3)

Third, the difference in installation space, the rising stem gate valve requires a larger installation space due to the stem; the height of the NRS gate valve is small, and it will not take up too much space during installation.
Fourth, the difference in application scope, the structure of the rising stem gate valve is beneficial to the lubrication of the stem, and the degree of opening and closing is obvious; the stem thread of the NRS stem gate valve is not only unable to be lubricated, but it is directly corroded by the medium and is easily damaged. Therefore, the RS gate valve is more The NRS stem gate valve has a wider range of applications.

The above is the difference between the RS gate valve and the NRS gate valve. Next, I will introduce you a little common sense, how to judge the RS gate valve and the NRS gate valve:

The stem of the RS gate valve drives the gate to move up and down together. The drive thread on the stem is outside the valve body. The opening and closing and position of the gate can be intuitively judged according to the movement direction and position of the stem; the drive thread of the NRS gate valve is located on the valve. Inside the body, during the opening and closing process, the valve stem only rotates, the gate moves up and down in the valve body, and the valve opens and closes until the steering wheel does not rotate.

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

Ways to Extend the Service Life of Valves

August 10, 2021

In industrial production, we always want to reduce costs, increase production capacity, and maximize profits. In addition to vigorously developing scientific and technological productivity, in daily work, paying attention to some small details, avoiding waste, can also reduce costs. Valves are disposable items and have their own service life. Once this period has passed, they must be replaced with new ones. Frequent replacement of valves will increase our production costs. Therefore, extending the service life of the valve can also maximize our production benefits. This article will start with the selection of the valve and tell us how to maximize the service life of the valve during the process of valve maintenance.

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

Valve selection
Getting the best performance level of the valve is the first step in ensuring the life of the valve, so we have to make sure that the right valve is selected and used in the right place. In many cases, the main reason for valve leakage and failure is the wrong valve design or the wrong material of construction. Therefore, when selecting a valve, you must be clear about the parameters of the pipelined medium, use temperature, pressure, etc., and select the correct and appropriate valve according to the parameters.

Valve installation
After purchasing a suitable valve, pay special attention to the installation. On-site technicians may cause further damage to the valve when removing the valve end cover. When the end cover is removed, dust and foreign matter will be deposited in the valve, which may cause Damage to the ball and valve seat, and cause leakage once installed. So do not open the end cap without special reason.
Incorrect hoisting of pneumatic valves or electric valves will damage the actuators and valves. When transporting the valve on site, there is a lifting ring on the valve. Do not lift the valve or actuator through the valve stem. Therefore, during the installation phase, the most important step is to purge the pipeline before it is pressurized.

Valve maintenance
After the valve is installed, frequent maintenance is required to prevent the valve and drive equipment from malfunctioning. Every month, the valve in operation should be moisturized to optimize the performance of the valve.

Finally, there are some caveats:
1. Make sure that the start of the valve and the material list of valve control accessories conform to our specification sheet.
2. The valve packaging must be inspected to ensure that the exterior of the valve and components are intact during the transportation process, and all grease fittings are present.
3. Ensure that the valve process connection is covered to prevent dust and debris from entering the body cavity.
4. Pay attention to the valve manufacturer’s instructions for lifting and transporting the valve.
Tanghai Valve, a high-quality valve manufacturer, has better quality and longer service life. Escort your production work.

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

How to choose a valve in the chemical industry

August 5, 2021

The media transported in various pipelines in the chemical industry are usually corrosive, such as sulfuric acid, hydrochloric acid, nitric acid and other corrosive media. All corrosion protection is the most basic requirement of chemical equipment. Chemical valves are of course no exception, and the selection of valve materials must be corrosion-resistant. If the chemical valve is wrongly selected, it will damage the equipment at the slightest level, or cause serious accidents, causing injury to machinery, equipment and even people. However, for different corrosive media, the selection of valves is also different. This article will talk about the key points of valve material selection for some common chemical media:

lug type butterfly valve, ductile iron, center lined,

Hydrochloric acid: Most metal materials, including various stainless steel materials, are not resistant to hydrochloric acid corrosion, and high-silicon ferro-molybdenum can only be used in hydrochloric acid below 50°C and 30%. Contrary to metal materials, most non-metal materials have good corrosion resistance to hydrochloric acid, so rubber-lined valves (such as fluoroplastics, etc.) are the best choice for transporting hydrochloric acid. But if the temperature of the medium exceeds 150°C, or the pressure is greater than 16 kg, any plastics (including fluoroplastics and even polytetrafluoroethylene) will be difficult to handle. For hydrochloric acid exceeding this condition, there is no ideal valve currently on the market.

Sulfuric acid: As one of the strong corrosive media, sulfuric acid is an important industrial raw material with a wide range of uses. Different concentrations and temperatures of sulfuric acid have great differences in the corrosion of materials. For concentrated sulfuric acid with a concentration of more than 80% and a temperature of less than 80°C, carbon steel and cast iron have good corrosion resistance, but it is not suitable for high-speed flowing sulfuric acid. Not suitable for use as a valve material; ordinary stainless steels such as 304 and 316 have limited use for sulfuric acid media. Therefore, pump valves for transporting sulfuric acid are usually made of high-silicon cast iron (difficult to cast and process) and high-alloy stainless steel (20 alloy valve). Fluoroplastics have better resistance to sulfuric acid, and fluorine-lined valves (recommended by Tanghai Valves) are a more economical choice. If the pressure is too high and the temperature rises, the point of use of the plastic valve will be impacted, and you can only choose the more expensive ceramic ball valve.

Nitric acid: Most metals are rapidly corroded and destroyed in nitric acid. Stainless steel is the most widely used nitric acid resistant material. It has good corrosion resistance to all concentrations of nitric acid at room temperature. Note that stainless steel containing molybdenum (such as 316, The corrosion resistance of 316L) to nitric acid is not better than that of ordinary stainless steel (such as 304, 321), and sometimes even worse.

Acetic acid: Acetic acid is one of the most corrosive substances in organic acids. Ordinary steel will be severely corroded in acetic acid at all concentrations and temperatures. Stainless steel is an excellent acetic acid resistant material. 316 stainless steel containing molybdenum is also suitable for high temperature and rarefied materials. Acetic acid vapor. For demanding requirements such as high temperature and high concentration of acetic acid or other corrosive media, high alloy stainless steel or fluoroplastic pumps can be used.

Salt water/sea water: The corrosion rate of ordinary steel in sodium chloride solution, sea water and salt water is not very high, and generally must be protected by paint; all kinds of stainless steel also have a very low uniform corrosion rate, but may cause local corrosion due to chloride ions. It is usually better to use 316 stainless steel.

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

Gate valve structure diagram and working principle

August 4, 2021

Gate valve structure; Working principle of gate valve
Gate valve /stop valve structure:
The gate valve refers to a valve in which the gate closing member moves along the vertical direction of the center line

rising stem gate valve-open and closed position

of the passage. Generally, it consists of valve body, valve seat, valve stem, gate, valve cover, and sealing ring. It can be transformed into a variety of electric gate valves and pneumatic gate valves by equipping transmission devices and gate valves. It is used for full-open and full-close cut-off, and cannot be used for adjustment and throttling. ,
Gate valve structure diagram Gate valve working principle:
The gate of the gate valve moves linearly with the valve stem. Usually there is a trapezoidal thread on the lifting rod. Through the nut on the top of the valve and the guide groove on the valve body, the rotary motion is changed into linear motion, that is, the operating torque is changed. For operating thrust. When the gate valve is closed, the sealing surface can only rely on the medium pressure to seal, that is, rely on the medium pressure to press the sealing surface of the gate to the valve seat on the other side to ensure the sealing of the sealing surface, which is self-sealing. Most gate valves adopt forced sealing, that is, when the valve is closed, the gate must be forced against the seat by external force to ensure the sealing performance of the sealing surface.

gate valve working diagram-3D GIF animated presentation

When the gate valve is opened, when the lift height of the gate is equal to 1:1 times the valve diameter, the fluid passage is completely unblocked, but this position cannot be monitored during operation. In actual use, the apex of the valve stem is used as the mark, that is, the unmovable position, as its fully open position. In order to take into account the lock-up phenomenon caused by temperature changes, it is usually opened to the top position, and then rewind 1/2-1 circle, as the position of the fully open valve. Therefore, the fully open position of the valve is determined by the position of the gate (ie stroke).

Posts

Factors Affecting the Operation and Use of resilient seated Butterfly Valves

Applicable occasions and application conditions of butterfly valves

Introduction to basic knowledge of gate valve

Installation and Maintenance of Butterfly Valve

resilient seated butterfly valve vs metal seated butterfly valve

Difference between NRS gate valve and RS gate valve

Ways to Extend the Service Life of Valves

Working principle and characteristics of triple eccentric butterfly valve

How to choose a valve in the chemical industry

Gate valve structure diagram and working principle

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