manufacturer Archives

Reasons and fixing for Leakage of the seat of the metal seated Gate Valve

November 8, 2021

The metal seated gate valve is well used in high temperature and high pressure media, but it also requires high quality due to the particularity of the working conditions, and the sealing problem that makes users most concerned about. What are the main reasons for leakage on the sealing surface? What measures can we take? The sealing

PN40-DN100 cast steel WCB gate valve photo

surface of the gate valve is the core part of the valve. There are four ways of leaking, namely, leakage of the sealing surface, leakage of the joint of the sealing ring, leakage caused by the falling of the closure and leakage of foreign objects embedded between the sealing surfaces. Today we mainly take a look at the leakage causes and solutions of the sealing surface.
1. The sealing surface of the metal sealing gate valve is unevenly ground and cannot form a tight line. Therefore, when the manufacturer grinds the sealing surface, grinding tools, abrasives, emery cloth, sandpaper and other objects should use reasonable grinding methods to be accurate. After grinding, they should be colored and checked. The sealing surface should be free of defects such as indentation, cracks, and scratches.
2. The top center of the connection between the valve stem and the closing part is suspended, incorrect or worn. In production, it is necessary to pay attention to the connection between the valve stem and the closure piece to meet the requirements. The top center should have a certain movable clearance, especially the axial clearance between the valve stem table and the closing part is not less than 2mm.
3. The valve stem is tortuous or the equipment is not right, which makes the closing part tilted or misaligned. If it is because of this situation, it is necessary to straighten and adjust in time to ensure that the valve stem, valve stem nut, closing parts, and valve seat are on a common axis after adjustment.
4. Unscientific selection of raw materials for the sealing surface or unsuitable working conditions of valve selection, resulting in corrosion, erosion and abrasion of the sealing surface. When selecting a valve or replacing the sealing surface, it should meet the working conditions.
5. Surfacing and heat treatment are not operated in accordance with the regulations. The defects such as wear due to low hardness, corrosion due to burning of alloy elements, and cracks due to excessive internal stress will also cause leakage of the sealing surface of the metal sealing gate valve. During the production process of the manufacturer, pay attention to the surfacing welding and heat treatment skills to meet the technical requirements of the compliance procedures and standards. After the sealing surface is processed, the inspection should be carried out to eliminate any shortcomings that affect the use.
6. The sealing surface is not tightly closed or the crevices appearing due to cold shrinkage after sealing, causing a phenomenon of eclipse. For high-temperature valves, some of the slits that show cold shrinkage after being closed should be closed again at a certain time after being closed to be used as a shut-off valve.
7. The metal sealing gate valve has reached the fully enclosed position and continues to exert excessive sealing force, including inaccurate use of long lever operation, and the sealing surface is crushed and squeezed. Therefore, whether it is a metal-sealed gate valve or not, all valves must be opened and closed in accordance with the operating specifications and signs given by the manufacturer. Strictly implement one-person operation or two-person operation according to the size of the valve handwheel, and whether levers within 500mm are allowed.
8. Excessive wear of the sealing surface causes the sealing pair to fail to fit perfectly. To prevent this situation, it should be adjusted in time, and the sealing surface that cannot be adjusted should be replaced.
The quality assurance of the metal seated gate valve is deeply related to the unevenness of the valve manufacturing quality, the quality of the working conditions, the quality of the operation, and the quality of maintenance. Only strict design and production of each link can ensure the safe operation of the valve without problems.

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

What kind of centerline wafer butterfly valve is a high-quality butterfly valve

November 5, 2021

There are many types of butterfly valves. Today we mainly want to discuss the centerline wafer butterfly valve, which is our more common type of butterfly valve. It has a wide range of applications, and currently there are many

Wafer type butterfly valve with worm gear

manufacturers of soft-seal wafer type butterfly valves. However, the quality and appearance of these butterfly valve products are still very different. How do we judge the quality of butterfly valves when we purchase butterfly valves? What are the characteristics and elements of a good centerline wafer butterfly valve? Tanghai Valve also summarized some of the feedback from many customers on-site and shared it with all users and friends.

1. Many of the centerline wafer butterfly valves are soft-sealed butterfly valves, lined with fluorine or rubber. Therefore, the quality of the material of the sealing pair requires high standards. Such as rubber, high-quality rubber can be long-lasting and elastic to play a good sealing role. However, the low-quality rubber hardened in a short time, and the valve naturally stuck or leaked internally. Therefore, in many cases, the final quality of the product is determined by details that are easily overlooked. For another example, the shaft hole on the valve stem and the valve body must have bushings, and the function of the bushing is to limit the bending deformation of the valve stem under pressure. The sealing ring between the valve stem and the valve stem shaft hole should be designed reasonably to ensure that the medium will not penetrate between the valve stem and the valve stem shaft hole. The bushing and sealing ring on the valve stem should not increase the torque too much.
2. Small torque, long service life, and good adjustment performance are all evaluation criteria.
3. Good airtightness and guaranteed leakage level!

To achieve good quality of the centerline wafer butterfly valve, butterfly valve manufacturers need to strictly control from several aspects. One is from the structure, such as bearings, valve stems, actuator connections, etc. are well-made. The design between the valve seat and the valve body can be more rationalized. Second, the processing technology is brave to innovate on the basis of maturity and adapt to more working conditions. Material selection should be scientifically optimized to ensure that the performance of the material meets the characteristics of the medium. In the selection, professional manufacturers should also provide customers with mature application experience to assist in purchasing. Actively collect feedback from users on product quality and respond to market demand in a timely manner.
The centerline wafer butterfly valve is very popular in the market, but any product has its own weaknesses. The weak point of the centerline pair clip-on butterfly valve is that when it is opened and closed, the unavoidable valve plate and valve wall are scratched and worn, which affects the service life. Therefore, Tanghai Valve is also actively launching a new double eccentric soft sealing butterfly valve. Due to the ingenious design of eccentricity, the valve plate can quickly leave the valve wall when it is opened, the sealing surface is protected, and the service life is longer. Coupled with a soft seal, the sealing performance is better. Tanghai’s double eccentric soft-seal butterfly valve also received very good market response soon after its launch. You are welcome to inquire.

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

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

November 3, 2021

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)

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 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

Operation precautions of stainless steel butterfly valve

November 2, 2021

Stainless steel butterfly valves are usually metal seated butterfly valves, which can be driven by manual, pneumatic, etc., and are suitable for use in high temperature and corrosive medium pipelines. Stainless steel butterfly valves are currently widely used in the market and can be seen in many fields. Especially in metallurgy, chemical industry,

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

building materials, power stations, glass and other industries in the dusty cold or hot air pipelines of ventilation and environmental protection projects, it plays an important role as a gas medium to adjust the flow or cut off the device.

Stainless steel butterfly valves mainly have the following two characteristics:
1. It is designed and manufactured with a new structure welded by a centerline disc plate and a short structure steel plate. It is compact in structure, light in weight, easy to install, small in flow resistance, large in circulation, avoiding the influence of high temperature expansion, and easy to operate.
2. There are no connecting rods, bolts, etc., so it works reliably and has a long service life. It can be installed in multiple positions and is not affected by the flow direction of the medium.
The advantages and disadvantages of stainless steel butterfly valves are: advantages. 1. It is convenient and quick to open and close, labor-saving, low fluid resistance, and can be operated frequently. 2. Simple structure, small size and light weight. 3. Mud can be transported, and the accumulation of liquid at the pipe mouth is the least. 4. Under low pressure, good sealing can be achieved. 5. Good adjustment performance. shortcoming. 1. The working pressure and working temperature range are small. 2. Poor airtightness.
In view of these characteristics, we first strictly follow the operating procedures in the instructions in our usual operations. Finally, pay attention to observe the valve opening and closing instructions and the operation of the valve stem, and the valve opening and closing degree must meet the requirements. In the process of opening and closing the valve, if the signal indicator is found to be wrong or the valve makes an abnormal sound, it should be shut down in time for inspection. We pay attention to these problems in daily use, so as to reduce the damage caused by operating errors in stainless steel butterfly valves.
Stainless steel butterfly valve is one of the valve products that many manufacturers need to purchase. Customers must pay attention to the selection of valve manufacturers when choosing specific valve parameters such as model size and caliber. Only by choosing a reputable and advantageous valve manufacturer can the valve quality be better and the later repairs more convenient.

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

Is it better to install gate valve or ball valve next to regulating valve?

November 1, 2021

Because both gate valve and ball valve can be used behind the regulating valve, the functions they undertake are basically similar. The two are only different in structure, so users often have questions about whether the gate valve is better or the ball valve is better. This is exactly what this article will discuss today.

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

Before the problem unfolds, we must first make it clear that there is no concept of which product is better for installing a gate valve or a ball valve before and after the regulating valve. Only the more suitable one can be selected according to the actual situation of the user and the working conditions. Let’s first briefly understand the characteristics of gate valves and ball valves.
In terms of function, the gate valve can be installed before and after the regulating valve, mainly used for water supply and hot water pipelines, commonly known as water valves. Generally not used on steam pipelines, because when the steam pressure is high, the gate is difficult to open under pressure, and it is also not suitable for use on pipelines with sediment. The sediment accumulates in the ram seat groove, which will cause the gate to close. strict. The opening and closing part of the 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 ball valve can also be installed before and after the regulating valve. It is mainly used to cut off, distribute and change the flow direction of the medium in the pipeline. It has the same action of rotating 90 degrees. The difference is that the cock body is a sphere with a circular through hole. Or the channel passes through its axis.
In terms of advantages, the more prominent advantages of gate valves are small resistance, short size, and low price. The relative advantage of ball valves is that they have better fluid control characteristics than gate valves. It only

electric ball valve

needs a 90-degree rotation operation and a small torque to close tightly. Ball valves are most suitable for use as on-off and shut-off valves.

From the above we can see that both gate valve and ball valve can be used before and after the regulating valve. Both of these valves are not suitable for flow control, but the ball valve has better fluid control characteristics than the gate valve, and the sealing performance is also better than that of the gate valve. . However, in actual installation cases, although gate valves and ball valves are installed before and after regulating valves, gate valves are more selected by users. This is why? details as follows:
1. It is troublesome to open and close the ball valve, and it has high requirements on the sealing surface. The sealing of the ball valve has strict requirements on the production and processing technology. If the correct manufacturer is not selected, it is easy to cause the internal leakage of the ball valve if the technology cannot meet the requirements. The cost is therefore relatively high, especially for large-caliber ball valves. The gate valve purchase cost is low, the sealing effect is good, the switch is relatively labor-saving, and when the gate valve is fully opened, it can provide the largest flow passage without causing resistance.
2. If the ball valve is in a static state for a long time, it will jam after a period of use.
3. The requirement of the ball valve for the medium is higher than that of the gate valve. For example, with more fibers and oxygen media, only ball valves can be used.
To sum up, whether it is better to install a gate valve or a ball valve before and after the control valve, we conclude that: Consider the economy, use the gate valve, and the gate valve is much cheaper. Or use gate valves on large-caliber, low-pressure oil, steam, and water pipelines. Considering the tightness, use the ball valve. The ball valve is suitable for working conditions with high requirements for leakage, and is suitable for fast opening and closing, and its quality life is better than that of gate valves.

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

cast steel gate valve vs stainless steel gate valve

October 29, 2021

The statement “cast steel gate valve is a gate valve made of stainless steel” is inaccurate. It is only a one-sided understanding of the two types of valves from the literal meaning. In fact, there are still very big differences between the two. Cast steel gate valves refer to all gate valves made of metal steel materials that are cast into castings. Such

PN40-DN100 cast steel WCB gate valve photo

gate valves are collectively referred to as cast steel gate valves. According to the material, it can also be divided into: carbon steel gate valve, stainless steel gate valve, low alloy steel gate valve (high temperature resistant chromium molybdenum steel belongs to this category), low temperature steel gate valve and so on. Corresponding to cast steel gate valves are also cast iron gate valves, forged steel gate valves, malleable cast iron gate valves.
I believe that at this time we can already see that the cast steel gate valve and the stainless steel gate valve are actually a molding method, that is, a process, and the other is a material type. Cast steel gate valves may be stainless steel gate valves, carbon steel gate valves, alloy steel gate valves. The stainless steel gate valve alone refers to the stainless steel valve, which can be cast or forged. In terms of scope: cast steel ≥ stainless steel valve.

Various cast steel gate valves correspond to different steel grades, which will be engraved on the valve body. The commonly used ones are as follows:
1. The grades of carbon steel gate valve castings are: WCA, WCB, WCC, LCB, etc.; applicable temperature is -46°C~425°C.
2. Stainless steel gate valve casting grades: 301 stainless steel, CF8 stainless steel (corresponding to forging 304 stainless steel), CF8M stainless steel (corresponding to forging 316 stainless steel), etc.; applicable temperature is -198 degrees ~ 816 degrees.

electric stainless steel gate valve

3. Low-alloy steel is divided into high-temperature alloy steel and high-strength low-alloy steel, among which high-temperature alloy steel is often referred to as chromium-molybdenum steel. Casting grades of chromium molybdenum steel gate valve: ZG1Cr5Mo, ZG15Cr1MoV, ZG20CrMoV, WC6, WC9, C12A, etc. The applicable temperature is between 550 degrees and 750 degrees.

The applicable temperature for each specific grade of material is different, depending on the actual working conditions.
Another point worth mentioning here is that cast steel gate valves and forged steel gate valves are often confused because of their similar names, making it unclear how to choose. In fact, the direct way to distinguish is to look at the material grades. For example, 304 stainless steel castings are generally marked as CF3 or CF8, and forgings are generally marked as 06Cr19Ni10 or directly marked as 304. The choice of cast steel gate valve or forged steel gate valve is mainly determined by the working conditions. Forged steel gate valves are mainly used when the medium conditions are special. Because forged steel gate valves are more mature in technology, many domestic manufacturers can do it. It can also be a general reference from the caliber. Generally, forged gate valves below DN40 and cast gate valves above DN40, the pressure will be lower for larger calibers than for smaller calibers. But in the end, of course, we must actively consider the actual requirements of customers, and manufacturers can give some reasonable suggestions.

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 metal seated butterfly valve in metallurgical field

October 28, 2021

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

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

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

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

Can cast steel gate valves and 304 stainless steel gate valves be universal?

October 27, 2021

Commonly used cast steel gate valves and 304 stainless steel gate valves are made of steel, and some customers think that stainless steel gate valves are more expensive than cast steel. Can they be universal if they have similar

electric stainless steel gate valve

performance. This is not possible. The two valves cannot be used universally, because the media they are applicable to are still different.
Stainless steel gate valve is more corrosion-resistant and durable! It can still easily hold media with high acid and alkali content, and can be applied to special media. Cast steel gate valves will not work. They are not resistant to acid and alkali. If they are in a medium with high acid and alkali content, they will rust after a while, and they will rust after a while. Cast steel gate valves are more suitable for common media, such as power plants.
Regarding the fact that stainless steel gate valves are more expensive than cast steel gate valves, it also requires specific analysis and cannot be summarized simply. For example, if you use high-density high-quality cast steel gate valves to compare with regular 304 stainless steel gate valves, the cast steel gate valves are more expensive. If it is a lower quality cast steel gate valve compared with a regular 304 stainless steel gate valve, then the stainless steel gate valve is expensive. So we still have to choose according to our own working conditions and make a good budget.

PN40-DN100 cast steel WCB gate valve photo

The types of stainless steel 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, double gate and elastic gate; parallel gate gate valves It 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. This type of valve should generally be installed horizontally in the pipeline.
To find a good gate valve product, first of all, a good manufacturer is very important. Tanghai Valve has focused on the production of gate valves for 24 years, with rich experience and good feedback from product users. It is your intimate valve procurement expert. You are welcome to visit the factory!

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 concentric |double eccentric |triple eccentric butterfly valve

October 26, 2021

The difference in butterfly valve structure distinguishes four types of butterfly valves, namely: concentric butterfly valve, single eccentric butterfly valve, double eccentric butterfly valve and triple eccentric butterfly valve. What is the concept of this eccentricity? How to decide when to use concentric butterfly valve, when to use single eccentric

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

butterfly valve, when to use double eccentric butterfly valve and triple eccentric butterfly valve? Many users are not particularly clear. We might as well share together.
Concentric butterfly valves, single eccentric butterfly valves, double eccentric butterfly valves and triple eccentric butterfly valves reflect the process of opening and closing more and more labor-saving, and the sealing surface wear is getting smaller and smaller. By setting the position of the shaft of the butterfly valve valve plate, the sealing and opening state of the butterfly valve can be changed. Under the same conditions, the torque of the valve is greater than one at each opening. When the valve is opened, the angle required for the valve plate to be separated from the seal is smaller than one.
The structural feature of the concentric butterfly valve is that the shaft center of the valve stem, the center of the butterfly plate, and the center of the valve body are in the same position. Generally, if you can use concentric butterfly valves in principle, use concentric butterfly valves as much as possible. Because the concentric butterfly valve does not require high sealing performance in terms of structure or operation, it is a conventional product. In order to overcome squeezing, scratching, and to ensure the sealing performance, the seat of the concentric butterfly valve is basically made of rubber or polytetrafluoroethylene and other elastic materials,

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

which is a soft sealing butterfly valve. This makes the concentric butterfly valve subject to temperature restrictions in use. In order to solve the problem of the squeezing of the butterfly plate and the valve seat of the concentric butterfly valve, a single eccentric butterfly valve was also produced. Its structural feature is that the shaft center of the valve stem deviates from the center of the butterfly plate.
Double eccentric butterfly valve is the most widely used. Its structural feature is that the shaft center of the valve stem deviates from the center of the butterfly plate and the center of the valve body. It deviates from the two center positions so it is called a double eccentric butterfly valve. Many double eccentric butterfly valves are line-sealed. When the sealing surface is closed, friction occurs between the disc and the valve seat, and the sealing effect is very good. It has the characteristics of small area and strong pressure. After the valve is opened, the butterfly plate can be quickly separated from the valve seat, which greatly eliminates unnecessary excessive squeezing and scratching of the butterfly plate and the valve seat, reduces the opening resistance, reduces the wear, and improves the life of the valve seat.
The triple eccentric butterfly valve is eccentric for the third time on the basis of the double eccentric butterfly valve. The shape of the sealing pair is not a positive cone, but an oblique cone. Mostly short-distance force and face seal. The stem shaft of the triple eccentric butterfly valve is a three-section shaft structure. The two shaft sections of this three-section shaft valve stem are concentric, and the center line of the central section shaft deviates from the axis of both ends by a center distance, and the butterfly plate is installed in the middle On the shaft section. Such an

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

eccentric structure makes the butterfly plate a double eccentric shape when in the fully open position, and a single eccentric shape when the butterfly plate rotates to the closed position. Due to the effect of the eccentric shaft, when it is close to closing, the butterfly plate moves a distance into the sealing cone surface of the valve seat, and the butterfly plate matches the sealing surface of the valve seat to achieve reliable sealing performance. It makes up for the contradiction that the hard seal has poor sealing, and the soft seal has good sealing effect but is not resistant to high temperatures. When to use a concentric butterfly valve and when to choose a double eccentric butterfly valve or a triple eccentric butterfly valve, it mainly depends on the usage habits and budget. If it is not for extreme working conditions, concentric butterfly valves can generally be selected, and concentric butterfly valves should be used as much as possible. Because the concentric butterfly valve is simple in structure and relatively economical in price.

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 gate valve products

October 25, 2021

Today, the professional gate valve manufacturer in Tanghai wants to share with you: Which one is better to choose between threaded gate valve and flanged gate valve? Threaded gate valve and flanged gate valve are common

threaded gate valve-inner screw-wedge-EPDM (1)

products in our daily use. Threaded gate valve is also called threaded gate valve. The biggest difference between it and flanged gate valve lies in the connection method. So to figure out whether to choose a threaded gate valve or a flanged gate valve, we only need to be clear about the factors that determine our connection method, so that it is easy to make a choice.
Generally speaking, the pressure and diameter of the pipeline have the greatest influence on the choice of connection. For gate valve products, threaded valves are used for DN80 and below, and flanged valves are used for DN80 and above valves. Sometimes flange connection is combined with threaded connection and welding connection, depending on the specific working conditions.
According to pressure conditions, flange gate valves are generally selected for high-pressure pipelines, and threaded gate valves are used for low pressure. Flange gate valves are stable and reliable when used in pipelines, so flange gate valves are often used in high-pressure pipelines. In summary, when the pressure is small, the pipe diameter is small, use threaded gate valve, and when the pressure is large, the flange gate valve is used when the pipe diameter is large.
Because flanged gate valves need to be welded to the pipeline, sometimes the material of the pipeline needs to be

DN1000-DIN-F5-NRS gate valve-IS&Y (6)

taken into consideration. The flanged gate valve should be selected when the pipe material is suitable for flange welding. If the pipe material is not suitable, other connection methods need to be considered. In addition, there are many kinds of flange materials, so you can listen to the manufacturer’s suggestions according to your own pipeline conditions.
When purchasing gate valves, users should make a simple understanding of the gate valve products and their connection methods from the manufacturer. In this way, when the manufacturer makes a recommendation, the purchaser will have a concept in mind, so as to choose the gate valve product that is more in line with the budget and adapts to the working conditions. Generally, the professional and technical personnel of Tanghai Valve will give detailed explanations to customers to ensure that customers will use and maintain, and are trusted by customers.

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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