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Structural characteristics and suitable medium of soft sealing gate valve

Structural characteristics of soft sealing gate valve:

Gate valves are mainly used in water-passing pipelines, but traditional gate valves may leak or corrode during use, which affects the performance of gate valves. As an upgraded product of traditional gate valves, the emergence of soft-sealed gate valves solves the problems of traditional gate valves that are easy to leak, easy to rust, and have poor elasticity. This article will give an introduction to the structural characteristics of soft sealing gate valves.

AWWA C509-C515-resilient seated wedge gate valve-DN80-150lb (4)

AWWA C509-C515-resilient seated wedge gate valve-DN80-150lb (4)

Soft sealing gate valve can be divided into dark rod soft sealing gate valve and rising rod soft sealing gate valve according to the structure. The working principle of the two structures is the same, the difference lies in the valve body structure, installation space, application range and so on. Details will be shared with you in future articles.

The structural characteristics of soft sealing gate valve are:
1. The valve body is made of ductile iron, which is lighter in weight and more conducive to installation and maintenance than traditional gate valves.
2. The valve body is coated with powder epoxy resin, which can play an anti-oxidation effect, prevent the valve body from being corroded, and is not easy to rust.
3. The traditional gate valve seat has grooves at the bottom. After the medium flows through, impurities in the medium such as stones, wood chips, iron chips and other debris will deposit and accumulate in the grooves at the bottom of the valve seat, which will cause the gate to fail to close completely over time. , causing leakage. The bottom of the valve seat of the soft-sealed gate valve is a flat-bottom design, and the medium containing impurities will not be precipitated and deposited when the valve body flows through, which ensures the sealing performance.
4. The gate of the soft-sealing gate valve is covered with high-quality rubber as a whole. The rubber and the gate are firmly attached, not easy to fall off, and have elastic memory, so that the gate and the valve seat can be tightly sealed to achieve good sealing performance. .

What medium is suitable for soft sealing butterfly valve:

In the introduction of the previous article, we learned that the sealing performance of the soft-sealed butterfly valve is superior, and it can achieve two-way sealing and zero leakage. The suitable media for soft seals are air, water, steam, various corrosive media, mud, oil, etc.
Butterfly valve can be divided into soft sealing butterfly valve and hard sealing butterfly valve according to the different sealing surface materials. The sealing surface refers to the valve seat of the butterfly valve. The sealing surface materials of the soft-seal butterfly valve we often see are EPDM, nitrile and PTFE. The three types of soft-sealed butterfly valves of different materials are also different in the applicable medium in the pipeline.

EPDM
Also called EPDM, codenamed EPDM. EPDM rubber is the most commonly used valve seat material for soft-seal butterfly valves, and it is also widely used. In the working environment of normal temperature and pressure, the use of EPDM valve seats has very good sealing performance. And EPDM rubber is resistant to ozone, aging, and has a long service life. The soft-sealed butterfly valve with EPDM as the valve seat material is suitable for fresh water, sewage, seawater and similar mud and other media containing impurities.

Nitrile
Nitrile-butadiene rubber, code-named NBR, has one of the biggest features of this material is its oil resistance is particularly good, in addition to a certain degree of wear resistance and heat resistance. The soft-sealed butterfly valve uses nitrile rubber as the sealing surface material, which can be used in oil pipelines and oily media. In addition, nitrile rubber is not suitable for medium such as fresh water, because it contains certain toxicity, which will cause harm to human health.

Teflon
PTFE is a fluoroplastic, code-named PTFE. The characteristics of PTFE are resistance to various acids and alkalis and various organic solvents; PTFE is used as the soft sealing partner of the valve seat material, which is mainly used in chemical industry, oil refining, chemical fiber, phosphate fertilizer, non-ferrous smelting, acid production, dyeing and other industries In the field, the applicable media are all corrosive strong acid and strong alkali media.
It can be seen from the above introduction that the soft sealing butterfly valve has a wide range of media and can be used in many fields. However, the soft sealing butterfly valve also has certain defects. Because of its own sealing material, it is not suitable for high temperature, high pressure and severe erosion conditions. In addition, in order to ensure the sealing performance of the soft-sealed butterfly valve, regular maintenance of its sealing surface should also be noted.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Video of resilient seated gate valve:

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What to consider when choosing a suitable resilient seated gate valve

The soft-seal /resilient seated gate valve is widely used. It is favored by users because it overcomes the product defects such as poor sealing and rust of ordinary gate valves. The soft sealing gate valve has a unique elastic seat seal to achieve a good sealing effect. The soft sealing gate valve is easy to open and close, reliable in sealing, good elastic

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

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

memory and long service life. It can be widely used as a regulating and intercepting device on the pipelines of tap water, sewage, construction, petroleum, chemical industry, food, medicine, textile, electric power, shipbuilding, metallurgy, energy system, etc.
To choose a resilient seated gate valve, you must first select the corresponding product according to the use environment, that is, the difference in the medium. Followed by some other technical parameters such as specifications, models and pressures. The correct selection can ensure the performance characteristics of the soft seal gate valve to the extreme, as well as the good operation of the pipeline, extend the service life of the pipeline, pump, and valve, and achieve the expected use effect of production. There are many types of rubber, but the best and economical ones are nitrile rubber and natural rubber. As an elastic sealing pair, they have high elasticity, high tensile strength, good abrasion resistance and drought resistance. Operating temperature range: about -60℃~80 ℃ Non-corrosive or general corrosive medium, can be water, gas, etc.
Soft seal gate valve, the inner cavity surface of the valve is not lined or covered with various rubbers, suitable for various working temperatures and fluid pipelines. Relatively speaking, as a resilient seated gate valve, rubber gate valves are not as resistant to high temperature and corrosion as fluorine-lined gate valves, which is a disadvantage of rubber seals. Fluorine-lined gate valve, also known as fluoroplastic-lined corrosion-resistant valve, is to place PTFE resin on the inner wall of steel or iron valve pressure-bearing parts or the outer surface of valve inner parts by moulding or inlaying, and use it in The unique performance of anti-corrosive medium is made into various valves.
When choosing a resilient seated gate valve, you must fully consider the main issues of medium, temperature, pressure, caliber, etc., to ensure that the use of the valve conforms to the working conditions and the characteristics of the product itself, and to maintain the service life.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

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Can a gate valve be used for oxygen as the medium?

If the soft-sealed gate valve you purchase will be used for oxygen media, the manufacturer will usually advise you not to do so, and inform you that it is prohibited to use gate valves in oxygen media pipelines in the specification. What

Grooved resilient seated BB NRS wedge gate valve (4)

Grooved resilient seated BB NRS wedge gate valve (4)

is the reason for this requirement? In fact, this is mainly related to the movement of the gate valve. The opening and closing method of the gate valve is the vertical movement of the gate. The gate and the valve seat will have strong friction and sparks may be generated. Since the contact between the valve plate and the valve seat is not continuous, it is also Static electricity may occur, which is very dangerous when used in flammable and explosive oxygen media pipelines. Let’s analyze it in detail below.

According to the characteristics of the gate valve: the gate valve should not be used to adjust the flow and pressure, otherwise, the sealing surface will wear out quickly and the tightness will decrease.

Moreover, the gate valve cannot be slowly opened for pressure adjustment, so the gate valve is not suitable for oxygen pipelines. One of the reasons why gate valves are forbidden in peroxygen pipelines is that the sealing surface of the gate valve will fall off from the sealing surface due to friction due to relative movement. Although this seems so trivial to us in normal times, in an environment of high-pressure pure oxygen, these small particles of iron powder are very easy to reach the ignition point and burn, and bury potential safety hazards.

Here, there is one more thing to pay attention to, that is, the safety hazards of the oxygen pipeline are not all to blame on the gate valve. When the pressure difference between the two sides of the valve is large, an explosion accident will also occur. Judging from the lessons learned from the accident, banning the gate valve is actually prohibiting the production of combustibles, and the purpose is the same as the regular removal of rust, degreasing, and banning oil. The need to further control the flow rate, do a good job of static grounding and other measures to eliminate the source of ignition, it has a great relationship with the valve material. Although copper-based alloy gate valves are more effective than cast iron and cast steel gate valves in preventing the production of combustibles, this does not mean that there are no hidden safety hazards. The reason is that there is no control of the fire source, and it is impossible to focus on the safety of the gate valve without controlling the source. The attention to operating pressure and the meticulous maintenance of the entire pipeline at all stages must tighten the nerve of safety, not just considering whether a gate valve is used.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

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Excellent environmental protection characteristics of soft sealing gate valve

In many working conditions, gate valves are more used to cut off water bodies such as pure water and tap water. Among them, the soft seal gate valve is an updated product of the ordinary gate valve. Generally speaking, as long as one side between the gate and the valve seat is made of soft material instead of metal, it can be called a soft seal. The

AWWA C509-C515-resilient seated wedge gate valve-DN80-150lb (4)

AWWA C509-C515-resilient seated wedge gate valve-DN80-150lb (4)

more common one is fluorine or rubber lining. The rubber-lined soft-seal gate valve we mentioned today mainly uses the overall nitrile rubber encapsulation outside the gate, and uses the softness of the rubber to seal the valve to achieve zero leakage in the valve. In addition to the advantages of sealing, the environmental protection characteristics of soft-seal gate valves are also excellent.
The gate plate of the soft-seal gate valve is made of pollution-free rubber material, and the inside and outside of the valve are sprayed with non-toxic epoxy resin electrostatically. This spraying process is advanced and environmentally friendly. It not only makes the appearance of the product smoother and more beautiful, but also does not produce rust water, which can meet the requirements of direct drinking water. Tanghai Valve has invested a huge amount of money to introduce an electrostatic spraying automatic assembly line, which has faster work efficiency. The soft sealing gate valve of Tanghai Valve is also widely used in fluid pipelines such as tap water, sewage, construction, fire fighting, HVAC, metallurgy, energy systems, etc., as a shut-off device. Under the country’s strong environmental protection call, some small factories with unsound qualifications but not enough to shut down have been forced to close under pressure. However, Tanghai Valve has steadily increased its sales due to the green and environmental characteristics of its products.
The soft sealing gate valve produced by Tanghai has extremely low resistance and light switch. At the same time, the “O” type sealing ring is adopted, which is reliable in sealing. The unique design structure enables the “O” type ring to be replaced under pressure, without pressing the packing, and free of maintenance. If you need gate valve products with high environmental performance, you will come to Tanghai Valve. After-sales quality is guaranteed, environmental protection quality is passed.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

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Characteristics of soft seal /resilient seated gate valves

Title: what are the characteristics of soft seal /resilient seated gate valves?

Traditional gate valves often have water leakage and corrosion. In order to overcome this shortcoming, the soft-seal gate valve appeared. As an updated product of the traditional gate valve, the soft-seal gate valve overcomes the shortcomings of poor sealing performance, poor elasticity, and easy corrosion of general gate valves.
The soft-seal gate valve uses a flexible rubber-wrapped gate, which uses the elastic energy of rubber to produce a small amount of deformation compensation, so that the valve can achieve a good sealing effect. The characteristics of the soft seal gate valve are as follows:

DIN-F5-BB-NRS-soft seated-wedge gate valve (10)

DIN-F5-BB-NRS-soft seated-wedge gate valve (10)

1. The gate is made of integral rubber
Use high-quality rubber to tightly wrap the gate of the soft-seal gate valve as a whole, which improves the sealing performance and is not easy to fall off.
2. The valve body is not easy to rust and corrosion resistant
The use of powder epoxy resin to coat the valve body of the soft-seal gate valve can effectively prevent the valve body from being oxidized, not easy to rust, and also prevent the valve body from being corroded. Soft-seal gate valves are often used in sewage treatment systems.
3. The valve seat is designed with a flat bottom
Traditional gate valves usually have a groove at the bottom of the valve seat. When the medium in the pipeline flows through the valve, impurities and particles contained in the medium will settle and silt in the bottom groove, which will make the valve unable to close tightly and cause leakage. Cause an accident. The bottom of the valve seat of the soft sealing gate valve is designed with a flat bottom and has no groove. After the medium in the pipeline flows through, there will be no siltation of impurities and particles, and the sealing performance of the valve is guaranteed to avoid leakage.
4. Precision casting valve body
The valve body of the soft sealing gate valve adopts precision casting, the size is accurate, and the inside of the valve body does not need to do any fine processing, and the sealing performance of the valve body is guaranteed.
5. Ductile iron valve body, light weight
The soft seal gate valve uses ductile iron as the valve body material. The overall weight of the valve is 20%-30% lighter than the traditional gate valve. The lighter weight makes the soft seal gate valve easier to install and maintain.
6. The inside of the valve body is not easy to be corroded
The valve body of the soft sealing gate valve is coated with non-toxic epoxy resin, and the gate is completely wrapped by rubber, which can effectively prevent the inside of the valve body from being corroded by the medium in the pipeline.
7. Three “O” seal ring seal design
The valve stem of the triple “O” seal ring seal design greatly reduces the friction resistance of the soft seal gate valve when it is closed, and the sealing performance is reliable, and no water leakage occurs; the unique design structure also makes the “O” seal ring It can be replaced under pressure and is maintenance-free.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Related news/knowledge:
Difference between Soft seal gate valve and hard seal gate valve
Difference between soft seal butterfly valve and hard seal butterfly valve
Electric ball valve-metal seated vs soft-seated type
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Resilient seated socket end gate valve

GATE VALVE-resilient seated SOCKET END
Standard: EN1074; EN1171

Socket ended resilient seated wedge gate valve-ductile iron (1)

Socket ended resilient seated wedge gate valve-ductile iron (1)

CAST IRON / DUCTILE IRON GATE VALVE SOCKET END
NON RISING STEM
Pressure: PN10 / PN16
Connection ends: Socked ends, for PVC pipes, uPVC pipes
FACE TO FACE: ACCORDING TO BS, DIN, ANSI, AWWA, SABS STANDARD ETC.
BODY:CAST IRON/DUCTILE IRON
BONNET:CAST IRON/DUCTILE IRON
WEDGE:CAST IRON/DUCTILE IRON, fully vulcanized with EPDM rubber
STEM: SS/BRASS
Coating: fusion bonded expoxy coating

The opening and closing part of the socket gate valve is a gate. The movement direction of the gate is perpendicular to the direction of the fluid. The gate valve can only be fully opened and fully closed, and cannot be adjusted or throttled. The gate has two sealing surfaces. The two sealing surfaces of the most commonly used mode gate valve form a wedge. The wedge angle varies with valve parameters, usually 50, and 2°52′ when the medium temperature is not high. The gate of the wedge gate valve can be made into a whole, called a rigid gate; it can also be made into a gate that can produce slight deformation to improve its manufacturability and compensate for the deviation of the sealing surface angle during the processing. The plate is called an elastic gate.

Socket gate valve can be divided into wedge gate valve and parallel gate valve according to the sealing surface configuration. The wedge gate valve can be divided into: single gate, double gate and elastic gate; parallel gate valve can be divided into It is single gate type and double gate type. According to the thread position of the valve stem, it can be divided into two types: rising stem gate valve and non-rising stem gate valve.

When the socket 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 against the valve seat on the other side to ensure the sealing of the sealing surface, which is self-sealing. Most gate valves use 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.

The gate of the socket gate valve moves linearly with the valve stem, which is called rising stem gate valve (also called rising stem gate valve). 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 into operating thrust.

When the valve is opened, when the lifting 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 a mark, that is, the position where it cannot be opened, as its fully open position. In order to take into account the locking phenomenon of the temperature change, it is usually at the top position of the opening, and then rewind 1/2-1 turn as the position of the fully open valve. Therefore, the fully open position of the valve is determined by the position of the gate (that is, the stroke).

Socket ended resilient seated wedge gate valve-ductile iron (2)

Socket ended resilient seated wedge gate valve-ductile iron (2)

In some gate valves, the stem nut is set on the gate, and the rotation of the handwheel drives the rotation of the valve stem to lift the gate. This kind of valve is called a rotating stem gate valve or a dark stem gate valve.

advantage:
The fluid resistance is small, and the sealing surface is less brushed and corroded by the medium.
It is easier to open and close.
The flow direction of the medium is not restricted, does not disturb the flow, and does not reduce the pressure.
The shape is simple, the length of the structure is short, the manufacturing process is good, and the scope of application is wide.

Disadvantages:
It is easy to cause erosion and scratches between the sealing surfaces, which makes maintenance difficult.
The overall size is large, opening requires a certain amount of space, and the opening and closing time is long.
The structure is more complicated.

The types of socket gate valves can be divided into wedge gate valves and parallel gate valves according to the sealing surface configuration. Wedge gate valves can be divided into: single gate type, double gate type and elastic gate type; parallel gate type Gate valves can be divided into single gate type and double gate type. Divided according to the thread position of the valve stem, it can be divided into two types: open stem gate valve and dark stem gate valve.

Matters needing attention in installation and maintenance
Handwheels, handles and transmission mechanisms are not allowed to be used for lifting, and collisions are strictly prohibited.
The double gate valve should be installed vertically (that is, the valve stem is in the vertical position and the handwheel is at the top).
The gate valve with bypass valve should be opened before opening (to balance the pressure difference between inlet and outlet and reduce the opening force).
The gate valve with transmission mechanism should be installed according to the product manual.
If the valve is frequently opened and closed, lubricate at least once a month.

Structural features:
The general gate valves used on the market for a long time generally have water leakage or rust. The company introduces the elastic seat seal gate valve produced by European high-tech rubber and valve manufacturing technology, which overcomes the defects of poor sealing and rust of general gate valves. The sealing gate valve uses the compensation effect of the elastic gate plate to produce a small amount of elastic deformation to achieve a good sealing effect. The valve has the obvious advantages of light switch, reliable sealing, good elastic memory and service life. It can be widely used as a regulating and intercepting device on the pipelines of tap water, sewage, construction, petroleum, chemical industry, food, medicine, textile, electric power, shipbuilding, metallurgy, energy system, etc.

 

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