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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

Resilient seated /soft-seal butterfly valve prices

October 22, 2021

The purchase price of soft-sealed butterfly valves is a problem that many customers are concerned about when inquiring, but because the valve is not like furniture and other items in the structure and material is relatively

wafer-type-butterfly-valve-with-handle-13

simple, there are more components of the valve, and according to the material used in different working conditions, The components are different, which makes it difficult to give a fixed quotation for the soft-sealed butterfly valve, which should be based on the actual situation. How much it costs to purchase a soft sealing butterfly valve has a lot to do with the material of the valve plate, the material of the valve body, the material of the sealing ring, manual or automatic, etc. Let’s take a look at the specific factors that affect the purchase price of soft-sealed butterfly valves?
1. Material of valve plate. The material of the valve plate of the soft sealing butterfly valve is nylon plate, galvanized plate, 304 plate, 316 plate, etc. The selection of the valve plate is determined according to the medium to be taken by the customer’s pipeline. The general medium mainly relates to whether it is corrosive. If it is not corrosive, you can choose galvanized sheet, and if it is corrosive, you can choose stainless steel 304 plate or 316 plate. Cold-rolled stainless steel costs more than 10,000 yuan per ton, while galvanized steel is several thousand yuan per ton, so obviously the price will be different for different materials.
2. Material of sealing ring. The sealing ring of soft sealing butterfly valve is generally rubber or fluoroplastic. The rubber sealing ring includes nitrile rubber, EPDM rubber, and tetrafluoro rubber. Several rubbers have their own advantages. Nitrile rubber is oil-resistant, and EPDM rubber is resistant to aging. PTFE rubber is resistant to weak corrosion. The temperature resistance of nitrile rubber and EPDM rubber is about 80 degrees, and the temperature resistance of tetrafluoro rubber is about 150 degrees. So we still have to choose according to the temperature and characteristics of the medium. If the temperature is around 80 degrees, you can choose nitrile rubber or EPDM rubber. If the temperature exceeds 80 degrees, you can choose tetrafluoro rubber. Fluoroplastics can also be used when the medium is corrosive but not high temperature. The price of fluoroplastics will be much more economical than rubber.
3. Manual or automatic. The soft sealing butterfly valve is divided into manual and automatic. Manual is the handle butterfly valve, turbine butterfly valve, the driving method is mainly manual. However, electric butterfly valves and pneumatic butterfly valves do not need to be operated manually but are opened and closed automatically by the device. Of course, the price is relatively higher than that of manual ones.
In addition to the above, the size of the valve’s caliber, the size of the applicable pressure, whether it is a flange connection or a wafer connection or an electric welding connection, these factors will all affect the purchase price of the soft sealing butterfly valve. So if you want to know the purchase price of the soft sealing butterfly valve you need, the easiest and best way is to quickly contact our Tanghai staff to give you a professional quotation. According to the working conditions, pressure and medium conditions you provide, Tanghai Professional Services will recommend the most suitable valve types for you and quickly give you an accurate quotation. 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

factors affecting the sealing performance of resilient butterfly valve seat

October 21, 2021

Rubber butterfly valve is an important part of regulating flow medium, and tight sealing is the most important quality of the product. The sealing performance of rubber butterfly valves is affected by many factors, and the most important influence is still closely related to the sealing surface. Today we will focus on three factors. Let’s take a

Wafer type butterfly valve with worm gear

look at the main factors that affect the sealing performance of rubber butterfly valves:

1. Quality of the sealing surface/valve seat
First of all, we must make it clear that the sealing surface refers to the part where the valve seat and the disc are in contact with each other for medium opening and closing control, and only which part of the valve seat and the disc are in contact instead of the entire sealing pair. The quality of the sealing surface is mainly related to the quality of the sealing material. The quality of the sealing material should be produced by the brand manufacturer and qualified in process. In addition, the choice of sealing material should be in line with the medium. For example, rubber butterfly valves cannot be used for highly corrosive media.

2. Width of sealing surface/valve seat
The width of the sealing surface mainly affects the movement resistance of the fluid. The larger the sealing surface, the lower the resistance, and the narrower the resistance is relatively large. Therefore, the increase in the width of the sealing surface can reduce the erosion and wear of the sealing surface by the fluid. At the same time, because the increase in the width of the sealing surface increases the length of the leakage stroke proportionally, the leakage can be reduced proportionally. However, the width of the sealing surface must not be excessively increased, because an increase in the width of the sealing surface, under the same sealing force, the reduction of the specific pressure of the seal will increase the possibility of leakage.

3. The pressure difference between before and after the valve
The specific pressure on the sealing surface is caused by the pressure difference between the front and rear of the valve and the applied sealing force, which refers to the pressure acting on a unit area of the sealing surface. The specific pressure directly affects the sealing performance, reliability and service life of the rubber butterfly valve. When the specific pressure on the sealing surface is small and the surface roughness is low, the leakage increases rapidly. When the specific pressure on the sealing surface is large, the effect of surface roughness on the leakage is significantly reduced.

In addition, the sealing performance of the rubber butterfly valve is related to the sealing surface material of the butterfly valve and its processing state, the nature of the medium, the existence of the sealing oil film, the rigidity and structural characteristics of the closing part, and so on. For more information, please call Tanghai for inquiries, and we will have professionals to answer your questions about butterfly 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

Excellent environmental protection characteristics of soft sealing gate valve

October 20, 2021

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)

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 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

Factors affect the sealing performance of butterfly valves

October 19, 2021

For the choice of butterfly valve, sealing is the most important attribute, because it directly affects the effect of butterfly valve throttling and is a direct manifestation of the quality of butterfly valve products. However, for most

wafer type butterfly valve, NBR seat (11)

working conditions, sealing does not mean that one drop is not allowed to leak. For the sealing performance of the butterfly valve, the accurate judgment standard should be: any sealing is allowed to have a small amount of leakage sometimes, if the leakage is not effective, it can be considered as sealed. The use experience of the valve shows that, in many cases, it is unnecessary to put high requirements on the sealing performance of the valve, because some working conditions completely allow a small amount of leakage of the medium, because this leakage is not enough to affect the use of the valve.
Of course, there are also more demanding working conditions in terms of sealing, usually for high pressure or corrosive media, and pipelines that transport flammable, explosive and toxic media. The leakage of the medium between the valve sealing surfaces may cause personal hazards, economic losses, and even In the event of an accident, etc., the tightness requirements should be reasonably put forward according to the danger level of the medium.
For example, for a hard-sealed butterfly valve, a certain amount of leakage is allowed when the sealing performance test is performed in the closed state in accordance with the technical standards for valve manufacturing. However, in order to ensure the high sealing performance of the hard-sealed butterfly valve, Tanghai Valve still carefully grinds the sealing surface, increasing the specific pressure on the sealing surface within the allowable specific pressure range of the sealing surface material, and improving the rigidity of the structure at the same time. At the same time, Tanghai Valve has stricter requirements on design, manufacturing and processing, such as:
(1) The quality of the valve body and bonnet, especially during forging or casting, should avoid defects and uneven composition such as folding, slag inclusion, pores, organization evacuation, and hidden cracks.
(2) The processing quality of the connecting parts of the valve stem and the valve body is improved, especially the roughness of the valve stem and the stuffing box, the straightness of the valve stem, the verticality of the stuffing box hole of the bonnet, and the processing accuracy are increased.
(3) The structure selection of the valve stuffing box. Since the seal at the valve stem is a dynamic seal, the packing is easy to wear during the rotation or sliding process of the valve stem. It is necessary to select a special low-leakage packing seal and packing seal combination, and strictly control the packing and packing. The gap between the valve stem, the gap between the packing and the stuffing box.
In summary, in addition to meeting the process conditions and standard specifications, the sealing performance of the control butterfly valve should also be fully considered for various operating conditions. In the engineering design, the sealing level of the butterfly valve should be selected to meet the principles of safety, reasonableness and economy.

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

Flange butterfly valve is more suitable for large and medium diameter pipelines

October 18, 2021

Commonly used butterfly valves include wafer butterfly valves, flanged butterfly valves and welded butterfly valves. Wafer type butterfly valve uses double-head bolts to connect the valve between two pipe flanges. Flange type

Double flange butterfly valve (16)

butterfly valve has flanges on the valve, and bolts are used to connect the flanges at both ends of the valve to the pipe flanges. The welding butterfly valve, as its name implies, is to weld the butterfly valve directly to the pipeline. The groove of the butt welding butterfly valve corresponds to the groove on the pipeline, and the welding rod is used to weld it. This type of connection is generally used in the case of high pressure media. Because welding is not easy to disassemble, the quality of the butterfly valve is required to be very high, and the price is naturally relatively high. Therefore, when DN50-300, flanged butterfly valve can be used, which is a cost-effective choice.
The flanged butterfly valve has its own flanges on both sides of the valve. Usually the flange and the valve body are cast together, so that the applicability to the pipeline is relatively strong, and it has the advantages of convenient installation and firmness. It is mainly used as a cut-off valve. Can have the function of a regulating valve. At present, flanged butterfly valves are used more and more on large and medium diameter, low pressure pipelines.
The butterfly plate of the flange butterfly valve is installed on the diameter side of the pipeline. The structural principle is very suitable for making large-diameter valves and has good fluid control characteristics. When the flange butterfly valve is in the fully open position, the thickness of the butterfly plate is the only resistance when the medium flows through the valve body. The larger the diameter, the lower the pressure. Therefore, the pressure drop generated by the flange butterfly valve is very small, so the flange butterfly valve can Actively play a role in large-diameter pipelines.
Flange butterfly valves are not only widely used in general industries such as petroleum, gas, chemical, water treatment, etc., but also used in cooling water systems of thermal power stations. The future market development prospects are bright.

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

Posts

cast steel gate valve vs stainless steel gate valve

Application of metal seated butterfly valve in metallurgical field

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

How to choose concentric |double eccentric |triple eccentric butterfly valve

How to choose gate valve products

Resilient seated /soft-seal butterfly valve prices

factors affecting the sealing performance of resilient butterfly valve seat

Excellent environmental protection characteristics of soft sealing gate valve

Factors affect the sealing performance of butterfly valves

Flange butterfly valve is more suitable for large and medium diameter pipelines

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