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The working principle of butterfly valve (picture)

June 15, 2021

Working principle of butterfly valve:
The butterfly valve is a valve that opens and closes according to the rotation of the valve stem, while driving the disc plate to rotate. In the cylindrical channel of the butterfly valve body, the disc-shaped butterfly plate rotates around the axis, mainly by rotating the disc plate 90° for flow control. When the disc reaches 90°, the valve is in a fully open state, and the angle of the disc can be changed to adjust the medium flow. It is generally installed in the

U-type-flange-butterfly-valve-2

diameter direction of the pipe. The butterfly valve and the valve stem have no locking ability. In order to effectively adjust the flow, a worm gear reducer is required. The butterfly valve with a worm gear reducer not only makes the butterfly valve self-locking, but also changes the operating performance of the butterfly valve and adjusts the medium flow more accurately. .
Features of butterfly valve:
(1) Simple structure and small size. Due to its compact structure, short structure length, small size and light weight, it is suitable for large diameters.
(2) The fluid resistance is small. When fully opened, the effective flow area of the valve seat channel is large, so the fluid resistance is small.
(3) The opening and closing is convenient and rapid, the adjustment performance is good, and the butterfly plate rotates 90. Both can complete the opening and closing. The flow can be controlled in stages by changing the rotation angle of the butterfly plate.

(4) The opening and closing moment is small, because the discs on both sides of the rotating shaft are basically the same under the action of the medium, and the direction of the torque is opposite, so the opening and closing is labor-saving.
(5) The low-pressure sealing performance is good, and the sealing surface material is generally rubber or plastic, so the sealing performance is good. Limited by the material of the sealing ring, the operating pressure and operating temperature range of the butterfly valve is relatively small. However, the working pressure and working temperature range of the hard seal butterfly valve have been greatly improved.

butterfly valve working diagram-3D GIF animated presentation

1. The butterfly valve has a small flow resistance when it is fully opened. When the opening is between about 15° and 70°, it can carry out sensitive flow control. Therefore, the application of butterfly valves is very common in the field of large-diameter adjustment. Since the movement of the butterfly plate of the butterfly valve is wiping, most butterfly valves can be used for media with suspended solid particles. Depending on the strength of the seal, it can also be used for powder and granular media.
2. The butterfly valve is suitable for flow adjustment. Because the pressure loss of the butterfly valve in the pipe is relatively large, about three times that of the gate valve, when selecting the butterfly valve, the influence of the pressure loss of the piping system should be fully considered, and the strength of the butterfly plate to withstand the pressure of the pipeline medium when it is closed should also be considered. . In addition, it is necessary to consider the limitation of the working temperature that the elastic valve seat material can withstand at high temperatures. To
3. The structural length and overall height of the butterfly valve are small, the opening and closing speed is faster, and it has good fluid control characteristics. The structure principle of butterfly valve is most suitable for making large-diameter valves. When a butterfly valve is required to control flow, the most important thing is to correctly select the specification and type of the butterfly valve so that it can work properly and effectively.
Related knowledge: Principles of butterfly valve structure
Related products: Electric switching butterfly valve Electric regulating butterfly 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

Electric ball valve principle | Electric ball valve working principle

June 15, 2021

Electric ball valve principle | Electric ball valve working principle
The electric ball valve is mainly composed of an electric actuator and a ball valve. The cock body is a ball with a 90-degree rotation. Electric ball valve is not only a good product for throttling, blocking, cutting, on-off, and diversion, it is also the first choice in the flow control system. It has many characteristics such as pressure resistance,

electric ball valve

temperature resistance, corrosion resistance, low flow resistance, long service life, and wide application range. To
The working principle of the electric ball valve: The electric ball valve mainly relies on the adjustment of the electric current in the electric actuator to operate the ball valve. The input and output signal of the electric actuator is 4-20mA and the standard signal of the 220VAC power supply. The motor group drives the gear and worm torque to control the opening and closing of the ball valve, to distribute and change the flow direction of the medium or to adjust the proportional degree of the spool rotation, namely The opening of the valve is proportional to the control fluid, or percentage.
Electric ball valve application:

electric V type ball valve

The electric ball valve does not need to be operated manually, but is operated intelligently. In the production process, the environmental site determines all the factors. Electric ball valves used in high pressure, high temperature or low pressure and low temperature environments are different. The following points should be noted:
1. For low temperature and low pressure, the material does not need to be adjusted too much.
2. In the case of high pressure and high temperature, high temperature and high pressure resistant materials should be used as the electric ball valve material, such as stainless steel and alloy, which can withstand high pressure and high temperature.
3. The internal parts of the electric ball valve need to be replaced to reduce the damage to the valve core, and it is also conducive to the flow of the medium and avoid the coking and blockage of the electric ball valve.
4. When the electric ball valve is opened, some machinery to avoid vibration can be installed to prevent the internal structure of the electric ball valve spool from being damaged when it is opened.

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

Ball valve model preparation method/code name establishment

June 11, 2021

Ball valve model preparation method/code name establishment in China.
With the rapid development of my country’s industrial modernization, the use of valves is also increasing. Ball valves have the advantages of fast opening and closing speed, and not only can switch and cut off, but also control flow, etc., and become the most widely used valve type. one! However, due to the wide variety of ball valves, including the use of pressure, temperature and control methods, the corresponding ball valve models are also different. In order to avoid errors in the selection of the user, and to ensure that the ball valve can be used normally, more instruments Self-Control Valve Company hereby provides instructions for the preparation of ball valve models for everyone to understand and recognize!

Pneumatic electric high platform ball valve

Ball valve model editing instructions are mainly from the increase of additional conditions of the ball valve, the selection of the drive mode, the difference of the connection form, the change of the structure form, the type of sealing material, the level of valve pressure and the material of the valve body, etc. to facilitate the explanation, hope It is helpful to the majority of users.
Ball valve model representation method:
Ball valve additional code: V means the valve core has a V-shaped structure, D means low temperature, B means heat preservation, P means eccentric structure, U, S and DY mostly mean top-mounted type;
Ball valve name code: Q means ball valve; Ball valve drive code: 2 means electro-hydraulic, 3 means turbine, 6 means pneumatic, 7 means hydraulic, 9 means electric, manual without code;
Code of connection method: 1 means internal thread, 4 means flange type, 6 means welding, 7 means wafer type;
Structural type code: Floating type: 1 means straight-through runner, 2 means Y-type tee, 4 means L-type tee, 5 means T-type tee; Fixed type: 0 means hemispherical through, 6 means four-way runner, 7 Means straight-through flow to, 8 means L-type tee, 9 means Y-type tee;

fixed ball valve

Sealing material code: B babbitt alloy, F fluorine rubber, F46 lining fluorine, H stainless steel, J rubber lining, M Monel alloy, N nylon plastic, Monel P, Y cemented carbide, W valve body directly processed;
Pressure rating code: 16 means the pressure is 16 kg (1.6Mpa) and the maximum can reach 64Mpa; 150LB means the American standard pound pressure, and the maximum pressure rating can reach 2500LB (150LB=1.6MPA/300LB=2.5-4.0mpa/400LB=6.4 mpa/600LB=10mpa); 5K means Japanese pressure, maximum pressure is 63K; Valve body material code: A titanium and titanium alloy, C carbon steel, I chromium molybdenum steel, P18-8 series stainless steel, RMo2Ti series stainless steel, S plastic.
ball valve model editing instructions:
Q645F-16P Stainless steel pneumatic flange three-way ball valve
1. Q: represents the ball valve;
2. 6: It means that the transmission mode is pneumatic;
3. 4: The connection method is flange connection;
4. 5: The structure is a floating T-type tee;
5. F: The sealing material is fluorine rubber;
6. 16: Indicates that the nominal pressure is 1.6MPa;
7. P: indicates that the valve body is made of stainless steel.

Editing instructions for electric ball valve model:
VQ947F-16P Stainless steel electric flange V-shaped ball valve
1. V: indicates that the spool has a V-shaped structure
2. Q: represents the ball valve;
3. 9: indicates that the transmission mode is electric;
4. 4: The connection method is flange connection;
5. 7: The structure is a fixed straight flow channel;
6. F: The sealing material is fluorine rubber;
7. 16: Indicates that the nominal pressure is 1.6MPa;
8. P: indicates that the valve body is made of stainless steel.

More details for valve model establishment, you can visit another article: https://www.tanghaivalve.com/valve-model-establishment-and-meaning/

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 telescopic butterfly valve application | advantages and disadvantages | installation instructions

June 10, 2021

Flange telescopic butterfly valve application|advantages and disadvantages|installation instructions
Flange telescopic butterfly valve application:
The butterfly plate of the flange telescopic butterfly valve is installed in the diameter direction of the pipeline. In the cylindrical passage of the telescopic butterfly valve body, the disc-shaped butterfly plate rotates around the axis, and the rotation angle is between 0° and 90°. When the rotation reaches 90°, the valve is fully opened. Applicable temperature≤80℃, used in petroleum, chemical, food, medicine, textile, papermaking, electric power, water supply and drainage, gas pipelines, as the function of regulating flow and intercepting medium, and has the function of compensating for thermal expansion and contraction of pipelines.

Double flange butterfly valve (16)

Advantages and disadvantages of flange telescopic butterfly valve:
Flange retractable butterfly valve (the structural length can be extended within a certain range), which not only brings convenience for valve disassembly, but also relieves pipeline stress and protects the valve. At the same time, it also condenses the installation method of butterfly valve plus retractor, and space More compact. Normally, this type of valve does not require special maintenance, and only needs to be regularly observed for leakage and pull-off in the telescopic part. The initial cost of flange expansion butterfly valve is lower than the installation method of flange butterfly valve plus expansion, but considering the maintenance cost in the future, the gain is not worth the loss.
If the sealing part of the butterfly valve is damaged and the sealing ring cannot be replaced and the butterfly valve needs to be scrapped, then the telescopic part will be scrapped together, resulting in greater loss. For example, when the sealing part of the butterfly valve needs maintenance, only the compression and expansion part cannot realize the valve-free online maintenance. However, the installation method of the butterfly valve and the expansion device has a great advantage. Only the expansion device needs to be removed, that is, manual Large maintenance space to realize valve free maintenance (butterfly valve is heavy, retractor is light, and labor intensity is low).
Precautions for installation of flange telescopic butterfly valve:
1. It is strictly forbidden to disassemble the butterfly valve of the disintegrated telescopic flange at the pipeline construction site; it is strictly forbidden to lengthen and shorten the telescopic butterfly valve repeatedly at the site.
2. The pipes at both ends of the telescopic valve must be concentric, and the two flange surfaces on the pipe must be parallel;
3. Flange fixing bolts should be tightened symmetrically, please do not forcibly tighten flange fixing bolts unilaterally;
4. The telescopic tube is installed behind the valve;
5. The expansion part of the expansion valve shall not be installed at the corner of the pipeline or at the end of the pipeline.
6. The telescopic flange butterfly valve must be placed flat before installation, and do not bump it at will;
7. The structural length of the telescopic flange butterfly valve is the minimum length when it leaves the factory, and when installed, it is pulled to the installation length (ie the design length);
8. When the length between the pipelines exceeds the installation length of the telescopic butterfly valve, please adjust the pipeline interval and do not force the telescopic valve to avoid damage to the telescopic valve;
9. The butterfly valve of the telescopic flange butterfly valve can be installed at any position. When used for temperature compensation, after the installation of the pipeline, brackets should be added along the two ends of the pipeline axis to prevent the telescopic valve telescopic tube from being pulled out. The support force of the bracket is calculated according to the following formula , It is strictly forbidden to remove the bracket during operation;
10. The telescopic flange butterfly valve does not do temperature compensation. At the same time, it is only used for installation, replacement, and maintenance. When the valve is convenient for use, it can be limited by bolts, and the telescopic flange butterfly valve can be clamped symmetrically to prevent the telescopic tube from being pulled out and damaging the telescopic butterfly valve and piping devices or buildings. Things. The bolt diameter can be calculated according to the flange bolt diameter, its bolt strength and test pressure and pipeline tension, according to the above formula. The limit bolts are strictly prohibited to be removed during operation (bolts are provided separately).

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

Wafer butterfly valve installation instructions and steps

June 10, 2021

Wafer butterfly valve is one of the most common types of valves in industrial pipelines. The wafer butterfly valve itself has a relatively small structure. You only need to put the butterfly valve in the middle of the flanges at both ends of the pipeline, and use stud bolts to pass through the pipeline flange and the The clip-on butterfly valve is locked to control the fluid medium in the pipeline. Wafer butterfly valve is especially suitable for places with narrow space or short distance between pipelines. When the 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. Therefore, the pressure drop generated by the valve is very high. Small, so it has better flow control characteristics.

wafer type butterfly valve, with handle (13)

1. Instructions before installation of wafer butterfly valve:
1. Before installation and operation, use air spray to remove foreign objects on the piping, and clean the inner surface of the piping with clean water.
2. Carefully check whether the valve usage is consistent with its performance specifications; (temperature, pressure)
3. Check the valve channel and sealing surface for debris, and remove it in time;
4. The valve must be installed in time after unpacking, please do not loosen any fastening screws or nuts on the valve at will;
5. Wafer butterfly valves must use special butterfly valve flanges.
6. The electric butterfly valve can be installed on the pipeline at any angle. For the convenience of maintenance, it is recommended not to install it upside down.
7. When installing the butterfly valve flange, it must be ensured that the flange surface and the sealing rubber are aligned, the screws are evenly tightened, and the sealing surface must fit completely; if the screw tightening force is uneven, the rubber bumps will block the butterfly plate, or the top Staying on the butterfly plate causes leakage at the valve stem. To
2. The installation steps of the wafer butterfly valve: The correct installation of the wafer butterfly valve is related to the sealing degree of the butterfly valve, and whether it will leak or not, including the safety in working conditions. The user should understand the installation process.

wafer & lug type butterfly valve (7)

1. As shown, place the valve between the two pre-installed flanges, paying attention to the alignment of the bolt holes.
2. Gently insert four pairs of bolts and nuts into the flange holes, and tighten the nuts slightly to correct the flatness of the flange surface;
3. Fix the flange to the pipeline by spot welding;
4. Remove the valve;
5. Fully weld and fix the flange on the pipeline;
6. Install the valve after the welding port has cooled down. Ensure that the valve has enough space in the flange to prevent the valve from being damaged, and ensure that the valve plate has a certain degree of opening;
7. Correct the valve position and tighten the four pairs of bolts (be careful not to over tighten)
8. Open the valve to ensure that the valve plate can be opened and closed freely, and then slightly open the valve plate;
9. Tighten all nuts in cross balance;
10. Reconfirm that the valve can open and close freely. Note: Confirm that the valve plate does not touch the pipeline.
The installation of the wafer butterfly valve must be laid flat before installation, remember not to bump it at will, after it is drawn to the installation length during installation, in the design of the on-site pipeline, it is not possible without special permission Disassemble the wafer butterfly valve at will, this is what we need to know before installation. At the same time, everyone should know that the wafer butterfly valve can be installed in any position, but after the wafer butterfly valve is installed, the butterfly valve needs to be laid along the line, and a bracket is made for the wafer butterfly valve. Once the bracket is made, it will be used At that time, it is strictly forbidden to remove the bracket.
Related products: Electric wafer butterfly valve Pneumatic wafer butterfly 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

Pneumatic ball valve-with high platform vs with bracket

June 9, 2021

The difference between pneumatic high platform ball valve and pneumatic ball valve with bracket
Pneumatic ball valve is one of the most widely used valve types in recent years. It is not only convenient in operation, but also very fast in execution. It is used in a variety of fields, such as petroleum, chemical, power generation, paper, food, and pharmaceutical industries. And in people’s daily lives. By connecting the air source, solenoid valve control, and related accessories, the pipeline can be quickly opened or closed, and it can also be intelligently controlled to achieve the adjustment of various process parameters such as pipeline media!

Schematic diagram of high platform ball valve

There are many types of pneumatic ball valves, which can be divided into various models according to pressure, material, connection form, applied medium, including control form. Today we will analyze the difference and choice between the pneumatic high platform ball valve and the ordinary pneumatic ball valve with bracket!
Description and advantages and disadvantages of pneumatic high platform ball valve:
Pneumatic high platform ball valve, as the name implies, is that the ball valve adopts a high platform design. The ISO standard is commonly used. The purpose of this is to facilitate the installation of the drive device. The connecting plate can be directly installed and connected with the (electric/pneumatic) actuator without a bracket. And connecting shaft. It can save costs by avoiding the bracket, improve production efficiency, and greatly improve the stability between the valve and the actuator, and the performance is very stable in use, so the application of the overall valve will not be affected by the looseness of the bracket or the large coupling gap. To
The advantage of pneumatic high platform ball valve is that its shape is more beautiful than ordinary ball valve, more refined, beautiful and generous, it takes up less space, and the structure is more compact. The disadvantage is that it is not resistant to high temperature, and the temperature is transmitted to the cylinder. The rubber ring in the cylinder is easy to age, and it is generally applicable. In the pipeline where the medium temperature is below 80 degrees. To
Description and advantages and disadvantages of pneumatic ball valve with bracket:
The use and function of the pneumatic bracket ball valve and the high platform ball valve are the same. The difference is that between the pneumatic bracket ball valve actuator and the ball valve body, there is a bracket supported, usually high medium temperature needs to be equipped with a bracket , This can avoid damage to the actuator due to high temperature. In layman’s terms, the ultimate purpose of the bracket is to extend the service life of the valve. The advantage of the pneumatic ball valve with bracket is that the heat dissipation function is relatively strong. For example, the medium temperature of the pipeline is above 300 degrees. At this time, it is recommended that the valve stem of the pneumatic ball valve should be correspondingly lengthened and the bracket should be attached at the same time. The reason for the extension of the valve stem with the bracket is to separate the valve body of the ball valve from the actuator, so as to prevent the medium temperature of the ball valve body from being too high, thereby affecting the service life of the actuator. For example, when the valve body of a ball valve is immersed in a liquid medium, and the liquid medium is strongly corrosive, the operator cannot approach it, and the actuator is outside the liquid surface, and the actuator needs to be operated by the staff. In this case It is necessary to choose a ball valve with a longer stem and a bracket, and if the liquid is strongly corrosive, the material of the ball valve must also be standard stainless steel, so as to ensure the normal operation of the pneumatic ball 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

Fluorine-lined valve instructions | Installation instructions

June 7, 2021

Fluorine-lined valve instructions | Installation instructions
1 The fluorine-lined valve flange cover cannot be opened at will. Unless it is ready to be connected to the pipeline, the PTFE flange surface may be bumped, scratched or deformed due to temperature differences and foreign objects, which may affect the sealing. If the cover is moved due to inspection needs, It is also necessary to quickly reset the cover plate after inspection to protect the PTFE flange surface.

Fluorine lined butterfly valve-PTFE-WAFER (9)

2 When the fluorine-lined valve is connected to the pipeline, the gasket is generally no longer used alone, but when it is connected with the flange surface of dissimilar materials (metal surface, etc.), appropriate gaskets should be used to protect the PTFE flange surface.
3 During the use of the fluorine-lined valve, if a leak occurs at a higher temperature, the system temperature should be lowered to room temperature first, and then the cause should be investigated and repaired.
4 During installation, the flange nuts should be evenly tightened in the diagonal direction (symmetrically), and matched with appropriate torque: a If the flange sealing surface leaks and the leak location nut is locked, the leak location nut should be loosened at this time Half a circle, and then apply the same torque to the opposite side to lock it again; b If the above method still does not stop the leakage, check whether the PTFE flange surface has unevenness, indentation, scratches, and then it can be leveled with fine gauze paper or cloth. reconnect.
5 It is not allowed to do any high temperature welding work on the fluorine-lined valve to avoid permanent damage to the lining layer.
6 Fluorine-lined valves should be stored in a dry and ventilated room. Stacking is strictly prohibited.
7 Fluorine-lined valves after maintenance must be tested and qualified according to relevant standards before they can be installed.
8 When manually operating the fluorine-lined valve, it is not allowed to force the valve to be opened or closed with the help of other levers.
9 When installing fluorine-lined valves with directional requirements, pay attention to the flow of the medium in the direction indicated by the arrow on the valve body, and ensure convenient operation and maintenance.
10 The sealing pair of fluorine-lined valves stored for a long time should be in a slightly separated state to avoid permanent deformation of the sealing surface under long-term pressure, which will affect the sealing performance and service life.

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

Valve seal (ring) material usage range comparison table

June 4, 2021

Valve seal (ring) material usage range comparison table
The selection of valve sealing material is determined according to the operating conditions of the valve, such as:

marine valve seat

pipeline medium, temperature range (high and low temperature), pressure, and internal structure of the valve. For different occasions, the selected seals are also different. Valve seals can generally be divided into two categories, soft seals and hard seals. Users should have a detailed understanding of their codes, operating temperature, pressure, medium and other parameters.

Comparison table of valve sealing material usage range:

Valve sealing material	Use range of valve sealing material
Rubber (X)	Nominal pressure PN ≤ 1 MPa, operating temperature t ≤ 150℃, applicable valves: globe valve, diaphragm valve, butterfly valve, check valve, etc.
Nylon (N)	Nominal pressure PN ≤ 32 MPa, operating temperature t ≤ 90℃, applicable valves: globe valves, ball valves, etc.
Polytetrafluoroethylene (F)	Nominal pressure PN ≤ 6.4 MPa, operating temperature t ≤ 180℃, applicable valves: globe valve, ball valve, gate valve, diaphragm valve, butterfly valve, check valve, etc.
Bus alloy (B)	Nominal pressure PN ≤ 2.5 MPa, operating temperature t ≤ 150℃, applicable valves: stop valves for ammonia, etc.
Ceramics (G)	Nominal pressure PN ≤ 1.6 MPa, operating temperature t ≤ 150℃, applicable valves: ball valves, plug valves, etc.
Enamel (C)	Nominal pressure PN ≤ 1.0 MPa, operating temperature t ≤ 80℃, applicable valves: globe valve, diaphragm valve, check valve, discharge valve, etc.
Copper alloy (T)	Nominal pressure PN ≤ 1.6 MPa, operating temperature t ≤ 200℃, applicable valves: gate valve, globe valve, check valve, plug valve, etc.
Stainless steel (H)	Nominal pressure PN ≤ 32 MPa, operating temperature t ≤ 450°C, applicable valves: globe valves, ball valves (medium and high pressure valves), etc.
Nitrided steel (D)	Nominal pressure PN ≤ 10 MPa, operating temperature t ≤ 540℃, applicable valve: power station gate valve, only for general use
Cemented carbide (Y)	Nominal pressure (PN) and operating temperature (t) are determined according to the material of the valve body. Applicable valves: high-pressure, ultra-high-pressure valves, high-temperature and low-temperature 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

Cryogenic valve principle |standard |illustration |selection

June 3, 2021

Principle of Cryogenic valve|Standard of Cryogenic valve|Selection of Cryogenic valve
The so-called cryogenic valve is a kind of altra-low temperature valve, as the name implies, is a valve suitable for working in cryogenic conditions. In the valve industry, valves that tend to -40°C are called cryogenic valves. Cryogenic valves are generally used in cryogenic systems such as liquid helium, liquid hydrogen, liquefied natural gas, and air separation. The medium used is liquid helium, liquid hydrogen, liquefied natural gas, liquid nitrogen, liquid oxygen and other cryogenic fluids. Under low temperature conditions, conventional metal hard seals and non-metal soft seals cannot meet the sealing requirements. In order to ensure that cryogenic valves can operate safely and reliably at low temperatures, there are some special considerations and requirements in the design and manufacture of cryogenic valves. see photo attached is a cryogenic triple offset butterfly valve.

triple offset valve parts-after-cryogenic process

Principle of ultra-low temperature valve: For valves used in ultra-low temperature conditions, the medium temperature is very low, and the metal materials will experience low temperature cold brittleness. The strength and hardness will be greatly improved, and the plasticity and toughness will be greatly reduced. This will directly affect the performance and safety of the valve. If an ordinary valve is used, the low temperature will freeze the packing in the valve stuffing box, and it will not be able to play a sealing role. In this way, the valve needs to be lengthened from the sealing seat on the bonnet to the bottom of the stuffing box. With sufficient isolation space and heat dissipation distance, the low-temperature medium in the valve body will not freeze the packing. As shown in the figure, the part marked with 175mm is the lengthened part.

In ultra-low temperature conditions, the valve stem and valve body can only adopt stuffing box or bellows structure. There are many restrictions on the use of bellows. Generally, the structure of the stuffing box seal is adopted. The stuffing box seal structure is simple to process and convenient to maintain. However, the sealing effect cannot be guaranteed under the condition of <-40℃, so the ultra-low temperature valves are all Keep the stuffing box as far away from the material as possible, and choose packing with low temperature characteristics.

Selection of ultra-low temperature valve:

cryogenic triple offset butterfly valve 1

Valve body: Ferritic stainless steel can be used when the temperature is higher than -100°C, austenitic stainless steel can be used when the temperature is lower than -100°C, copper alloy or aluminum alloy can be used for low-pressure and small-diameter valves. Stem: Made of austenitic stainless acid-resistant steel, it needs to be properly heat-treated to increase the tensile strength. At the same time, it must be hard chrome plated (coating thickness 0.04~0.06mm) or nitriding treatment to increase the surface hardness.

Gasket: When the working temperature is higher than -196℃ and the maximum low temperature working pressure is 3MPa, the asbestos rubber sheet made from long fiber can be used; when the working temperature is higher than -196℃ and the maximum low temperature working pressure is 5MPa, it can be used. Stainless steel spiral wound gasket with asbestos, stainless steel spiral wound gasket with PTFE, or stainless steel spiral wound gasket with expanded graphite.

Fasteners: when the temperature is higher than -100°C, the bolt material is Ni, Cr-Mo and other alloy steels, which need to be properly heat-treated to prevent thread bite; when the temperature is lower than -100°C, the bolt material can be austenitic Body stainless steel. The nut material is generally Mo steel or Ni steel, and the thread surface is coated with key disulfide.

Ultra-low temperature valve design standards:

1. Design: API6D, JB/T7749

2. Valve routine inspection and test: according to API598 standard.

3. Low temperature inspection and test of valve: According to JB/T7749.

4. Drive mode: manual, bevel gear drive and electric drive device.

5. Valve seat form: The valve seat adopts a welded structure, and the sealing surface is welded with cobalt-based hard alloy to ensure the sealing performance of the valve.

6. The ram adopts an elastic structure, and a pressure relief hole is designed at the pressure inlet end.

7. One-way sealing valve body is marked with flow direction mark.

8. The low-temperature ball valve, gate valve, and stop valve adopt a long neck structure to protect the packing.

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

The difference between API, DIN valve and GB valve

June 2, 2021

The difference between American standard valve, German standard valve and national standard valve
(American Standard, German Standard, National Standard) The difference between valves:
First of all, it can be distinguished from the standard codes of various countries: GB is the national standard of China, the American standard (ANSI), and the German standard (DIN). Secondly, it can be distinguished from the model. The valve model of the national standard is named according to the pinyin letter of the valve category. For example, the safety valve is A Butterfly valve D Diaphragm valve G Check valve H Stop valve J Throttle valve L Sewage valve P Ball valve Q Trap valve S Gate valve Z and so on. ,

Globe valve (9)

There are no special specifications between American standard valves, German standard valves, and national standard valves. It is nothing more than the difference between production standards and pressure levels. The material of the valve body and internal parts are easy to say, it is nothing but cast iron, cast steel, stainless steel, etc. Taking the American standard as an example, the pressure level of the American standard ranges from 125LB to 2500LB (or 200PSI to 6000PSI), and the main standard is API, ANSI, commonly referred to as API, and ANSI valves are American standard valves; German standard valve pressures are usually PN10 to PN320. DIN standard; if it is a flanged valve, the corresponding flange standard must be adopted. The world’s major valve standards are also the American Standard Petroleum Institute API standard, the American national standard ANSI, the German standard DIN, the Japanese standard JIS, the national standard GB, the European standard EN, and the British standard BS. ,

float_ball_check_valve

Simply put, American standard valves are valves designed, manufactured, produced, and tested according to American standards. German standard valves are valves designed, manufactured, produced and tested according to German standards. The national standard valve is a valve designed, manufactured, produced and tested according to our country’s standards. The differences between the three are roughly as follows: 1. The flange standards are different; 2. The structural length is different; 3. The inspection requirements are different.
(American Standard, German Standard, National Standard) Valve Standard:
China National Standard (GB)
Chinese Ministry of Machinery Standards (JB)
American National Standard (ANSI)
American Petroleum Institute Standards (API)
American Society for Testing and Materials Standards (ASTM)
American Valve and Fitting Manufacturer Standardization Society Standard (MSS)
Japanese Industrial Standard (JIS)

German National Standard (DIN)
French National Standard (NF)
British National Standard, European Standard (BS, EN)
Other national valve standards (ГOCT, IEEE, UL)

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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