News Archives

Knife Gate Valve Structure and Working Principle

February 16, 2022

Knife gate valve, also called knife type gate valve, is a kind of gate valve. The structural feature of the knife gate valve is that there is an oblique cut at the bottom of its valve plate. Like a knife edge, this knife-shaped oblique cut can easily cut off the medium circulating in the pipeline, so that the valve can be closed without being blocked by the medium. Below is the structure diagram of the knife gate valve.

Knife gate valve (6)

Knife gate valves are generally used in medium pipelines such as pulp, slag, coal ash, sewage, and chemical raw materials. They can only be fully opened and fully closed. They are used as shut-off valves and cannot be used for flow regulation. The transmission modes of the knife gate valve are manual, pneumatic, electric, etc., and its working principle is also very simple. The following takes the manual knife gate valve as an example to introduce the working principle of the knife gate valve to you.
The working principle of the manual knife gate valve is to turn the handwheel by hand to make the valve stem rise or fall, thereby driving the gate to move up and down to achieve the purpose of opening or closing the valve. Turn the handwheel clockwise, the gate goes down, and the valve closes. Turn the handwheel counterclockwise, the gate rises, and the valve opens.
Compared with the traditional gate valve, the structure of the knife gate valve is simpler, the length and size are smaller, and it is easier to install, disassemble and maintain. Knife gate valves are suitable for use in medium pipelines with high consistency and solid particles. The gate like a guillotine has a better gate breaking effect, and can effectively cut off various impurities contained in the medium in the pipeline, completely solving the leakage phenomenon of the traditional gate valve after passing through the medium containing particulate impurities.
Knife gate valves have very short structural lengths and take up little space. The full-bore knife gate valve design allows the valve to be used in dirty media, and the replaceable seat and packing also make valve maintenance easier.
Although the performance of the knife gate valve is better than that of the traditional gate valve, the price of the knife gate valve is higher than that of the traditional gate valve, so the knife gate valve cannot completely replace the traditional gate valve at present.

Knife gate valve installation and use:
1. Before installation, check the valve cavity and sealing surface, and do not allow dirt or sand to adhere;
2. The bolts of each connecting part should be tightened evenly;
3. Check that the packing parts are required to be pressed tightly, not only to ensure the sealing of the packing, but also to ensure the flexible opening of the gate;
4. Before installing the valve, the user must check the valve model, connection size and pay attention to the flow direction of the medium to ensure the consistency with the valve requirements;
5. When installing the valve, the user must reserve the necessary space for the valve drive;
6. The wiring of the drive device must be carried out according to the circuit diagram;
7. The knife gate valve must be maintained regularly, and must not be collided and squeezed at will, so as not to affect the sealing.

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

Video of knife gate valve:

Sealing Surface Structure of Handle Wafer Type Butterfly Valve

February 14, 2022

The sealing surface structure of the handle wafer butterfly valve is the key to ensure the reliable sealing of the valve and an important basis for judging the performance of the valve. The sealing performance is related to whether the butterfly valve can perform normal adjustment and cut off the medium work. In general, the sealing surface is

JIS 10K-wafer butterfly valve-backup seat (1)

composed of the valve seat and the disc of the wafer butterfly valve. It depends on the close contact between the valve seat and two or more precision-machined and ground sealing surfaces on the disc, or the sealing surface is produced by pressure. The sealing is achieved by plastic deformation.

The sealing surface of the handle wafer butterfly valve:
1. Resistant to medium corrosion;
2. Wear resistance and friction;
3. Ensure reliable sealing under the current working conditions;
4. Good processing technology;
5. Easy to assemble and maintain.

The sealing surface form of the handle wafer butterfly valve:
The sealing surface of the valve has several forms, including flat seal, cone seal, spherical seal, and knife seal. The handle wafer butterfly valve is mainly flat seal and spherical seal. The concept of flat seal is that the two contact surfaces of the seal are flat. Compared with several other sealing forms, the flat seal has its own unique advantages, the most important being the convenience of processing and repair. If it is used on the globe valve, it can also make the valve open and close without friction at the moment. Spherical seal means that one of the two contact surfaces of the seal is spherical. Butterfly valves with good sealing performance, ball valves and some small-diameter globe valves are used more. The advantage of the spherical seal is that the seal is larger and the sealing performance is good, but the disadvantage is that the maintenance is more difficult.
There are many fastening forms for the sealing surface of the handle wafer butterfly valve, which are mainly determined according to the conditions of the medium used, such as the pressure, temperature, corrosiveness of the medium, and the properties of the material of the sealing ring and the material of the housing. The basic requirements for the tightening of the valve sealing ring are that the joint surface has good sealing, easy processing, convenient maintenance, reliable connection and durability.

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

Video of center-lined butterfly valve:

What is the principle of triple eccentric butterfly valve

February 11, 2022

Triple eccentric butterfly valve is a kind of butterfly valve with outstanding performance in industrial pipelines. According to the sealing form, triple eccentric butterfly valve belongs to the category of hard sealing butterfly valve. Therefore, the triple eccentric butterfly valve has the characteristics of a hard-sealed butterfly valve, which is

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

resistant to high temperature, erosion, and has a long service life. And because the triple eccentric butterfly valve directly welds the high temperature corrosion resistant alloy material on the valve seat surface, the valve also has the same excellent sealing performance as the soft sealing butterfly valve. So what is the principle of triple eccentric butterfly valve? What are the three eccentricities of the triple eccentricity? Why use a triple eccentric structure?

The sealing surface of the triple eccentric butterfly valve is an inclined conical surface. The valve seat of the valve body is in contact with the sealing ring of the butterfly plate. Its working principle is to drive the movement of the butterfly plate by operating the transmission device. During the movement of the butterfly plate, its sealing The ring is in full contact with the valve seat because of the elastic deformation to achieve the seal.
A prominent feature of the triple eccentric butterfly valve is that the sealing structure of the valve is changed. It is no longer a traditional position seal, but a torsion seal, that is to say, it does not rely on the elastic deformation of the valve seat to achieve sealing, but relies on the sealing surface of the butterfly plate. The contact surface pressure with the valve

triple eccentric butterfly valve-wafer-lug-double flange-welded (5)

seat is used to achieve the sealing effect, which also solves the problem of large leakage of the metal valve seat, and because the contact surface pressure is proportional to the medium pressure, the triple eccentric butterfly valve has a strong high pressure and high temperature resistance.

Three eccentric butterfly valve three eccentric
The first eccentricity: the deviation from the plane of the sealing surface to the centerline of the valve stem;
The second eccentricity: the distance from the centerline of the valve body to the centerline of the stem;
The third eccentricity: there is an included angle between the center line of the cone surface where the sealing surface of the valve body is located and the center line of the valve body channel.

Reasons for using triple eccentric structure
The use of triple eccentric structure can reduce the friction between the sealing surface of the disc and the sealing surface of the valve body when opening or closing, so that the disc can quickly disengage or release the valve seat when the triple eccentric butterfly valve is opened or closed, reducing the operation time. torque, the operation is more labor-saving and light, and the service life of the sealing surface of the butterfly valve is increased.

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

Video of triple eccentric butterfly valve:

Properties of triple eccentric butterfly valve

February 10, 2022

Performance advantages of triple eccentric butterfly valve:
1. It integrates adjustment and cut-off, and has strong controllability.
The design of the new triple eccentric butterfly valve adopts a double safety structure. In order to prevent the deformation of the disc, the dislocation of the valve stem, and the occlusion of the sealing surface caused by the

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

influence of fluid pressure and temperature, two independent stoppers are installed on the upper and lower sides of the disc. The push ring ensures the normal operation of the valve under any working conditions; in order to prevent the valve stem from being damaged and flying out and causing unexpected accidents, independent valve stem flying-out prevention mechanisms are designed at the lower end of the valve inside and outside.
2. No dead zone design, small opening torque.
The shape of the valve plate of the triple eccentric butterfly valve is an elliptical cone, and its surface is surfacing with hard alloy, which has excellent wear resistance. The floating U-shaped stainless steel valve seat has the function of automatically adjusting the center. When the valve is opened, the valve plate of the elliptical cone sealing surface is first separated from the U-shaped elastic valve seat, and then rotated; when the valve is closed, the valve plate rotates, and the valve plate automatically adjusts the center to the elastic valve seat under the action of the eccentric shaft. Seat pressure deforms the seat until the seat is in close contact with the oval conical sealing surface of the valve plate. When the valve is switched on and off, the disc does not scratch the valve seat, the torque of the valve stem is directly transmitted to the sealing surface through the disc, and the opening torque is small, thus eliminating the common jumping phenomenon when opening the valve, that is, eradicating the dead zone (no sense band) . This design without dead zone enables the triple eccentric butterfly valve to enter the controllable area almost from 0 opening to 90 opening, and its control ratio can be as high as 1001 or more, which is twice that of ordinary butterfly valves.
3. Zero leakage, high temperature and high pressure resistance.
The biggest feature of triple eccentricity is that it fundamentally changes the sealing structure. It is no longer a position seal, but a torsion seal, that is, it does not rely on the elastic deformation of the valve seat, but completely relies on the contact surface pressure of the valve seat to achieve the sealing effect. This sealing structure enables the triple eccentric butterfly valve to achieve a hard seal of level VI and achieve true zero leakage. At the same time, due to the selection of the metal valve seat and the structural characteristics of the face seal, the problem of high temperature and high pressure resistance is also easily solved. In addition, the triple eccentric butterfly valve adopts the body seat structure, which makes the valve structure more compact, and reduces the chance of the valve seat directly contacting the medium, reduces the degree of erosion of the valve seat, and can effectively prevent small solids in the medium. The impact of the material and thermal expansion may cause the sealing surface to bite, thereby extending the service life of the valve seat. The new triple eccentric butterfly valve can not only replace the body seat, but also the disc sealing surface and disc are independent, and the disc sealing surface can also be replaced, which greatly reduces the maintenance cost.

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

Video of triple eccentric butterfly valve:

introduction of micro-resistance slow-closing butterfly check valve

January 25, 2022

Introduction of Micro-resistance Slow-closing Butterfly Check Valve
The structure of the butterfly check valve is very simple, and its structural length is also very short compared to other check valves. Butterfly check valve is also called butterfly check valve. The connection method is wafer type. The

micro resistance butterfly check valve (3)

valve plate is two semicircular butterfly plates. The two butterfly plates are connected by the valve stem and are forced to reset by spring. The working principle of the butterfly check valve is: when the medium flows through the valve body channel, the medium pressure is greater than the force of the spring, and the two discs are pushed open, the valve is opened, and the medium flows; when the medium stops flowing, the two discs Then due to the force of the spring, the valve is forced to reset, and the valve is closed, and the backflow of the medium is prevented at the same time.
Butterfly check valve is also known as double-clip check valve. Its sealing surface can be surfacing wear-resistant material or lined with rubber. It has a wide range of use and reliable sealing. Butterfly check valves are automatic valves and do not require manual operation. This type of valve is usually used in pure pipelines, as well as pipelines in the fields of industry, environmental protection, water treatment, and high-rise building water supply and drainage, to prevent the backflow of the medium. To prevent the reverse flow of the medium.
The main code is HH46 HH48 HH49
Micro-resistance slow-closing butterfly check valve application
It is mainly used in the supply and drainage pipelines of purified water, source water, sewage, seawater and other media. It is installed at the outlet of the pump to cut off the backflow of the medium to eliminate destructive water hammer, protect the pipeline and make the pump run safely.
Features of Micro-resistance Slow-closing Butterfly Check Valve

micro resistance butterfly check valve (4)

1. Small in size, light in weight, and only about one-third of the length of the swing check valve, it is more suitable for use in pipelines with limited space.
2. The slow closing system has excellent performance, long-term movement does not fail, can effectively control the slow closing of the valve disc, and can eliminate the destructive water hammer.
3. Rubber soft seal, good sealing performance, wear resistance, long service life and better stability. .
4. There is a closing spring on the valve disc, which opens and closes smoothly, without vibration and noise.
5. The flow channel is usually small in fluid resistance, sensitive in opening and closing of the valve plate, and good in sealing performance.
6. Compared with other check valves, the flow resistance is smaller, and it has obvious energy saving effect.

Micro-resistance slow-closing butterfly check valve main parts and materials

Part Name	Material
valve body	Gray cast iron, carbon steel, ductile iron, stainless steel
Disc	Cast steel, ductile iron, stainless steel
stem, spring	Stainless steel
Slow closing device, micro-control valve	Stainless steel

Main technical parameters of micro-resistance slow-closing butterfly check valve

Nominal pressure (Mpa)	Shell test pressure (MPa)	Sealing test pressure (MPa)	proper temperature	Applicable media	Slow closing time
1	1.5	1.1	≤80℃	clean water, sewage, sea water	3-60 seconds
1.6	2.4	1.76
2.5	3.75	2.75

Product structure diagram of micro-resistance slow-closing butterfly check valve

structure diagram of micro resistance butterfly check valve

The main connection dimensions of some products of the micro-resistance slow-closing butterfly check valve (unit: mm)

main dimensions-sizes of micro resistance butterfly check valve

Working principle of micro-resistance slow-closing butterfly check valve

This check valve is mainly composed of a valve body, two semicircular discs, a return spring, an oil storage cylinder, a slow-closing small cylinder group, and a needle valve (micro-adjustment valve). Relying on the thrust of the imported medium, the two valve discs are pushed open smoothly. At the same time, the imported pressure medium enters the lower part of the piston in the oil cylinder, pushes the piston, and presses the oil on the upper part of the piston into the tail end of the small cylinder on both sides of the valve body through the needle valve, so that the piston rod in the small cylinder extends. When the inlet medium pressure drops below the outlet pressure, the medium will flow back, and the valve flap will automatically close under the action of the spring and the medium backflow. However, since the piston rod is in the extended position, it cannot be fully closed against the valve disc, and there is still about 20% of the area left for the medium to pass through, thus eliminating the water hammer. The valve disc is divided into two steps by the piston to quickly close first and then slowly to close, which can not only prevent the motor from reversing, but also play the role of eliminating mute.

Installation of Micro-resistance Slow-closing Butterfly Check Valve

1. The check valve can be installed horizontally (the arrow is parallel to the horizontal ground), or it can be installed vertically (the arrow is vertical to the horizontal ground).
2. Before installation, the pipeline should be cleaned, and the valve should be fully inspected to ensure that it is not damaged and then loaded into the pipeline. When loading, pay attention to the direction of the arrow and the running direction of the medium.
3. A filter should be installed at the inlet of the valve. A butterfly valve or gate valve should be installed at the outlet to facilitate the maintenance of the valve and other equipment.
4. When tightening the flange connecting bolts, attention should be paid to the symmetry, uniformity and firmness.
5. For a check valve with a working pressure greater than 1.0 MPa, the strength and tightness test should be carried out before installation, and it can be used only after passing the test. During the strength test, the test pressure is 1.5 times the nominal pressure, and the duration is not less than 5 minutes. The valve housing and packing should be qualified without leakage. During the tightness test, the test pressure is 1.1 times the nominal pressure; the duration of the test meets the requirements of GB 50243.
6. The check valve cannot bear the weight in the pipeline, and the large check valve should be supported independently so that it will not be affected by the pressure generated by the pipeline system.

Operation and debugging of micro-resistance slow-closing butterfly check valve

1. Initial test debugging
Close the needle valve on the oil reservoir clockwise, then open it counterclockwise for 3-5 turns.

2. Operation adjustment
After starting the water pump, observe whether there is oil leakage or water leakage at each connection of the slow-closing system. At the same time, use a wrench to loosen the screw plug on the needle valve body by one or two turns, so that the air in the slow-closing system can be discharged, and then quickly tighten the screw plug until there is leakage. When the pipeline pressure rises to a certain pressure, stop the pump and observe, there may be two situations at this time:

(1) The seal does not die when closed, and the motor reaches the speed of rotation faster. The reason for this phenomenon is that the opening of the needle valve is too small, and the pressure oil in the small cylinder does not return to the oil storage cylinder in a short time, so that the valve disc cannot be closed for a long time. At this point, just turn the needle valve counterclockwise half a turn to one turn.

(2) The seal is closed quickly, and the pipeline produces a great vibration sound. There are two reasons for this phenomenon: A) Because the opening of the needle valve is too large, the oil in the small cylinder quickly returns to the oil storage cylinder, that is, the valve disc is quickly closed to produce water hammer. At this time, try to close the small needle valve clockwise. If the small needle valve is closed and the pump is turned on for the second time, there is still a loud vibration when the pump is stopped again, which belongs to the reason B. B) The piston in the small cylinder does not extend. Check whether the needle valve is open, gently loosen the oil pipe joint at the small cylinder, and observe whether there is oil coming out. If there is oil leakage, it is proved that the oil circuit is unblocked. At this time, it may be because the oil in the oil storage is not enough, please refuel urgently. Refueling method: Disassemble the oil pipe joints on both sides of the needle valve, remove the needle valve counterclockwise with a wrench, insert a steel rod with a diameter of about 12mm and a length of about 300mm into the oil cylinder, and use a hammer to gently press the oil cylinder into the oil cylinder. The piston is knocked into the bottom end, at this time, add 20# oil to the oil cylinder, then install the needle valve, and then connect the copper pipe.
After the operation is adjusted, there is no need to move all parts, and it will work automatically and normally in the future.

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

Video of center-lined butterfly valve: https://youtu.be/NuSZH_AJcwY
Video of double eccentric butterfly valve: https://youtu.be/yOw2xp3bIaE
Video of triple eccentric butterfly valve: https://youtu.be/AkRwg2X1Wh0
Video of dual plate wafer check valve: https://youtu.be/XqRRI7o-LFI
Video of knife gate valve: https://youtu.be/vFSbTF_FGXM
Video of PTFE butterfly valve: https://youtu.be/Lutith_TJD0
Video of resilient seated gate valve: https://youtu.be/AI-LT1dy2sU

Types and Models of Butterfly Valves

January 24, 2022

With the advancement of science and technology, the production process of butterfly valves has become more and more sophisticated, and different types have been extended from this, and their uses have become more and more extensive. What are the types of butterfly valves? What is the corresponding model? This article will take you to understand the types and models of butterfly valves.

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

Types of Butterfly Valves
There are many classifications of butterfly valves, and different classification forms can divide butterfly valves into different types. Let’s talk about it specifically.
1. According to the different connection forms, it can be divided into wafer butterfly valve, flanged butterfly valve, welded butterfly valve, threaded butterfly valve, clamp butterfly valve and so on. The most commonly used connection forms are wafer butterfly valve and flanged butterfly valve.
2. According to the different transmission modes, it can be divided into handle butterfly valve, turbine butterfly valve, pneumatic butterfly valve, electric butterfly valve, hydraulic butterfly valve, solenoid valve, etc. The most common transmission methods are handle, turbine, pneumatic and electric. The handle butterfly valve and turbine butterfly valve are collectively referred to as manual butterfly valve.
3. According to the material of the sealing surface, it can be divided into soft sealing butterfly valve and hard sealing butterfly valve. The sealing performance of the soft-seal butterfly valve is better than that of the hard-seal butterfly valve. The commonly used materials for the sealing surface of the soft-seal butterfly valve are EPDM, nitrile rubber and PTFE. Hard-sealed butterfly valves are mainly used in high temperature and high pressure conditions.
4. According to different structural forms, it can be divided into centerline butterfly valve, single eccentric butterfly valve, double eccentric butterfly valve and triple eccentric butterfly valve. Among them, the midline butterfly valve generally uses a soft seal; the eccentric butterfly valve uses a hard seal. The triple eccentric butterfly valve is the valve with the best performance at present. It not only has the excellent sealing performance of the soft sealing butterfly valve, but also has the characteristics of high temperature and high pressure resistance and corrosion resistance of the hard sealing butterfly valve.
5. According to the different working pressure, it can be divided into vacuum butterfly valve (nominal pressure lower than standard atmospheric pressure), low pressure butterfly valve (nominal pressure PN<1.6MPa), medium pressure butterfly valve (nominal pressure PN2.5-6.4MPa), high pressure butterfly valve (nominal pressure PN2.5-6.4MPa) Nominal pressure PN10.0-80.0MPa), ultra-high pressure butterfly valve (nominal pressure PN>100MPa). A high-quality butterfly valve manufacturer, Tanghai Valve mainly produces low-pressure butterfly valves and medium-pressure butterfly valves.
The above is an introduction to the types of butterfly valves. For the description of butterfly valve models, you can refer to the article “Method of Representing Butterfly Valve Models”. The code name of the butterfly valve is D. The commonly used butterfly valve models include D71X, D371X, D671X, D971X for the wafer type of the soft-sealed butterfly valve, and D41X, D341X, D641X, and D941X for the flange type. Among them, X represents the rubber material. Pipes with corrosive media can be replaced with F fluoroplastics. For hard sealing, you only need to change X or F, that is, the material of the sealing surface, to H, that is, the metal material.

The types and models of butterfly valves are introduced here. For more butterfly valve information, you are welcome to visit the official website of Tanghai Valve.

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

Video of center-lined butterfly valve: https://youtu.be/NuSZH_AJcwY
Video of double eccentric butterfly valve: https://youtu.be/yOw2xp3bIaE
Video of triple eccentric butterfly valve: https://youtu.be/AkRwg2X1Wh0
Video of PTFE butterfly valve: https://youtu.be/Lutith_TJD0

Advantages and Disadvantages of Triple Eccentric Butterfly Valves

January 21, 2022

The triple eccentric butterfly valve is a new type of butterfly valve product. Before the advent of the triple eccentric butterfly valve, the soft sealing butterfly valve and the single eccentric double eccentric metal hard sealing butterfly

triple eccentric butterfly valve-

valve were the most used in industrial pipelines. These two types of butterfly valves have their own advantages, but also have obvious disadvantages. The advantage of soft sealing butterfly valve is that it has good sealing performance and can achieve zero leakage; the disadvantage is that it is not suitable for high temperature and high pressure environment and is not resistant to wear. The advantage of hard sealing butterfly valve is that it can adapt to high temperature and high pressure working conditions, but the sealing performance is very poor. In order to solve the shortcomings of the two types of butterfly valves and better serve our production work, the triple eccentric butterfly valve came into being and has been widely used.

Advantages of triple eccentric butterfly valve
The triple eccentric butterfly valve also belongs to the metal hard sealing butterfly valve. The technology makes the triple eccentric butterfly valve more resistant to high temperature and high pressure environment and more corrosion resistant than traditional butterfly valve products. At the same time, due to the unique design of the triple eccentricity, the valve is very easy to operate. When opening and closing, the disc and the valve body have no friction. When the valve is closed, the torque of the transmission mechanism increases to provide a compensation seal, which greatly improves the triple eccentricity. The sealing performance of the butterfly valve also prolongs the service life of the butterfly valve. So what do the three eccentricities of the triple eccentricity mean?
1st eccentric: The valve shaft is located behind the valve plate shaft, allowing the seal to have a complete tight encircling contact with the entire valve seat.
The second eccentricity: the centerline of the valve shaft is offset from the centerline of the pipe and valve, which is free from the interference of valve opening and closing.
3rd eccentricity: The valve seat cone shaft is offset from the centerline of the valve shaft, which eliminates friction during closing and opening and achieves a uniform compression seal around the entire valve seat.

Disadvantages of triple eccentric butterfly valve
No matter how perfect things are, there will be more or less defects and imperfections, and the triple eccentric butterfly valve is no exception. Its shortcomings have the following two points:
1. Due to the special process of the triple eccentric butterfly valve, the structure of the butterfly plate will be relatively thick, so if a butterfly valve with a triple eccentric structure is used on a small-diameter pipeline, the resistance of the butterfly plate to the circulating medium in the pipeline will be very large in the open state, and the flow of The resistance is large, so generally speaking, the triple eccentric butterfly valve is not suitable for small diameter pipelines below DN200.
2. In the normally open pipeline, the sealing surface of the valve seat of the triple eccentric butterfly valve and all layers of the sealing ring on the butterfly plate will be washed by the front, which will affect the sealing performance of the valve for a long time.

The above is the introduction of Tanghai valve for the advantages and disadvantages of triple eccentric butterfly valve. If you have purchase requirements for triple eccentric butterfly valves, 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

Video of triple eccentric butterfly valve:

Which valves are used for wastewater and sewage treatment

January 20, 2022

Which valves are used for wastewater and sewage treatment? The continuous increase of water pollution in my country has made the sewage treatment and regeneration industry receive unprecedented attention. In the sewage treatment pipeline system, the valve plays a very important role.

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

Definition of sewage treatment
Sewage treatment: The process of purifying sewage in order to make it meet the water quality requirements for discharge into a body of water or for reuse. Sewage treatment is widely used in construction, agriculture, transportation, energy, petrochemical, environmental protection, urban landscape, medical treatment, catering and other fields, and is increasingly entering the daily life of ordinary people.

Sewage treatment classification
According to the classification of sewage sources, sewage treatment is generally divided into production sewage treatment and domestic sewage treatment. Production sewage includes industrial sewage, agricultural sewage and medical sewage, etc., while domestic sewage is sewage generated in daily life, which refers to the complex mixture of various forms of inorganic and organic substances, including: ① floating and suspended solid particles; ② glue shape and gel-like diffusion; ③ pure solution.
According to the quality of water pollution, there are two types of water pollution: one is natural pollution; the other is man-made pollution. At present, man-made pollution is the most harmful to water bodies. Water pollution can be divided into three categories: chemical pollution, physical pollution and biological pollution according to the different pollution impurities. The main pollutants are: (1) industrial wastewater discharged without treatment; (2) domestic sewage discharged without treatment; (3) farmland sewage with extensive use of chemical fertilizers, pesticides, and herbicides; (4) industrial waste and domestic garbage piled up by the river ; ⑸ soil erosion; ⑹ mine sewage.

Sewage treatment valve
Modern sewage treatment technology can be divided into primary, secondary and tertiary treatment according to the degree of treatment. Generally, the degree of sewage treatment is determined according to the water quality and the destination of the treated water. The valves used at each level are also different.
primary treatment
It mainly removes suspended solid pollutants in sewage, and most of the physical treatment methods can only complete the requirements of primary treatment. After primary treatment of sewage, BOD can generally be removed by about 30%, which does not meet the discharge standard. The primary treatment belongs to the preprocessing of the secondary treatment. Valves and their pipeline accessories are used: knife gate valve, triple eccentric butterfly valve, filter, etc.
secondary processing
It mainly removes colloidal and dissolved organic pollutants (BOD, COD substances) in the sewage, and the removal rate can reach more than 90%, so that the organic pollutants can meet the discharge standard, and the suspended solids removal rate can reach 95%, and the effluent effect is good. The valves used are soft-sealed butterfly valves, gate valves, ball valves, check valves, etc.
tertiary treatment
Further treatment of refractory organic matter, nitrogen and phosphorus and other soluble inorganic matter that can lead to eutrophication of water bodies. The main methods are biological denitrification and phosphorus removal, coagulation sedimentation, sand filtration, activated carbon adsorption, ion exchange and electrodialysis. The valves used are wafer butterfly valve, gate valve, ball valve, check valve, rubber soft joint, etc.

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

Video of center-lined butterfly valve: https://youtu.be/NuSZH_AJcwY
Video of triple eccentric butterfly valve: https://youtu.be/AkRwg2X1Wh0
Video of dual plate wafer check valve: https://youtu.be/XqRRI7o-LFI
Video of knife gate valve: https://youtu.be/vFSbTF_FGXM
Video of resilient seated gate valve: https://youtu.be/AI-LT1dy2sU

Precautions for the application of fluorine-lined valves

January 19, 2022

Appropriate selection and application of fluorine-lined anti-corrosion valves is a matter of concern to everyone in engineering. Tanghai Valve puts forward the following views based on years of field application experience for your reference. We are specialised in the production of fluorine lined butterfly valves.

lug butterfly valve-lined-PTFE-DI body (1)

The price of fluorine-lined butterfly valves is much lower than that of corrosion-resistant stainless steel valves and Hastelloy valves. Some metal valves with strong corrosive media cannot be used, but only plastic-lined valves can be used well. However, the plastic-lined valve must be suitable for application. It is hoped that several technical conditions such as application pressure and application temperature should be used. Take our company’s products as an example to illustrate the following:
(1) The temperature of the medium used in the fluorine-lined valve: Usually, the fluorine plastic used in the fluorine-lined valve is F46 (FEP), and the temperature of the medium used cannot exceed 150 °C (the medium temperature can reach 150 °C in a short time, and the temperature of the long-term use It should be around 120℃), otherwise, the F46 lining of various parts of the valve is easy to soften and deform, resulting in the valve not closing and the leakage is large.
If the temperature of the medium used by the user is below 180 °C for a short time and below 150 °C for a long time, another fluoroplastic, PFA, can be used, but the price of fluoroplastic lined with PFA is more expensive, so it should be used in advance when matching. Inquiry.
(2) Do not have negative pressure. Fluoroplastic-lined valves should avoid negative pressure in the pipelines used. If there is negative pressure, it is easy to cause the fluoroplastic-lined layer of the valve cavity to be sucked out (bulged) and shelled, resulting in failure of the valve to open and close.
(3) The pressure and differential pressure should be controlled within the allowable range. Especially the fluorine-plastic-lined regulating valve and globe valve sealed by bellows. Because the bellows is made of tetrafluoro material, the pressure is high and the pressure difference is high, which can easily lead to the rupture of the bellows.
Bellows-sealed fluoroplastic-lined regulating valve can be changed to PTFE packing seal if the operating condition pressure and differential pressure are high.
(4) The medium conditions used in the fluoroplastic valve should not have hard particles, crystallization, impurities, etc., so as to prevent the valve from breaking the valve core, the fluoroplastic layer of the valve seat or the tetrafluoro bellows during the opening and closing operation. For the medium with hard particles, crystals and impurities, when selecting, the valve core and valve seat can be changed to Hastelloy, but additional inquiry is required.

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

Video of PTFE butterfly valve:

Introduction to Common Butterfly Valve Materials

January 14, 2022

This article makes an introduction to the commonly used butterfly valve materials. For butterfly valves, you should already have a certain understanding. There are many types of butterfly valves. According to the different connection forms, they can be divided into wafer butterfly valves and flanged butterfly valves; according to different sealing surface materials, they can be divided into soft sealing butterfly valves and metal hard sealing. Butterfly valve;

Types of wafer butterfly valves

according to the different driving methods, it can be divided into handle butterfly valve, turbine butterfly valve, pneumatic butterfly valve, electric butterfly valve and so on. So what are the commonly used butterfly valve materials?
Commonly used butterfly valve materials are mainly cast iron, cast steel, stainless steel three categories. Each material can be further subdivided. Below we will give an introduction to these three types of butterfly valve materials.

Category 1: Cast Iron
Cast iron is subdivided into four categories: gray cast iron, malleable cast iron, ductile iron, and nickel cast iron. This article mainly introduces the two main cast iron materials made by Tanghai valve: gray cast iron, ductile iron and stainless steel.

lug butterfly valve-lined-PTFE-DI body (1)

Gray cast iron is cast iron with flake graphite, because the fracture is dark gray when broken, so it is called gray cast iron. Gray cast iron is the most widely used cast iron, and its output accounts for more than 80% of the total output of cast iron. The casting performance, cutting performance and wear resistance of gray cast iron are very good. Its disadvantage is that its strength, plasticity and toughness are lower than other cast irons.
Grey cast iron is used as the material of butterfly valve, which is usually suitable for weak acid and weak alkali media such as water and air, but not suitable for pipelines with perhydrochloric acid and nitric acid media.
Ductile iron is a high-strength cast iron material with very high strength, toughness and wear resistance, and its comprehensive performance is close to that of steel. At present, the application range of ductile iron is second only to gray cast iron. We often say “replace steel with iron”, which refers to ductile iron.

U type flange butterfly valve (4)

Ductile iron is used as the material of butterfly valve, which has certain corrosion resistance and performance is much higher than that of butterfly valve made of gray iron. The applicable medium includes steam, general gas and oil.

The second category: cast steel
Cast steel is a cast iron alloy, which is a general term for iron-based alloys used to produce castings that do not undergo eutectic transformation during solidification. The advantages of cast steel are greater design flexibility and variability, increased overall structural strength and a wide range of weight variations. Using cast steel as the butterfly valve material, the performance is better than that of cast iron but not as good as stainless steel. Butterfly valve made of cast steel is suitable for steam, non-corrosive gas, oil, etc.

The third category: stainless steel
Stainless steel refers to steel that is resistant to weak corrosive media such as air, steam, and water, and chemically corrosive media such as acid, alkali, and salt, also known as stainless acid-resistant steel. Generally, the butterfly valve made of stainless steel has the best performance and can be used in more severe working conditions. It is used in some ultra-high temperature, ultra-low temperature and strong acid-base corrosive medium pipelines. Wear-resistant and long-lasting.

The above is the introduction of commonly used butterfly valve materials. Generally speaking, the price of stainless steel butterfly valve is the highest, and gray cast iron is the cheapest. If you want to know more about butterfly valve, you are welcome to visit Tanghai Valve”

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

Video of center-lined butterfly valve:

Knife Gate Valve Structure and Working Principle

Sealing Surface Structure of Handle Wafer Type Butterfly Valve

What is the principle of triple eccentric butterfly valve

Properties of triple eccentric butterfly valve

introduction of micro-resistance slow-closing butterfly check valve

Types and Models of Butterfly Valves

Advantages and Disadvantages of Triple Eccentric Butterfly Valves

Which valves are used for wastewater and sewage treatment

Precautions for the application of fluorine-lined valves

Introduction to Common Butterfly Valve Materials

TH VALVE • PROFESSIONAL VALVE MANUFACTURER

GET IN TOUCH WITH US