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The correct operation method of manual valve

The manual valve is operated by the operator with the help of a handle or a hand wheel to manipulate the opening and closing of the valve by manpower. When the valve opening and closing torque is large, a turbine device needs to be installed between the handle or hand wheel and the valve stem, which is more labor-saving. . Normally, the switching direction of a manual valve is to pull the handle or handwheel of the valve, turn it clockwise in the thorium direction to close, and turn it counterclockwise to open the valve. However, under special circumstances, the opening and closing direction of the manual valve may be reversed. This requires operators, especially those experienced

Wafer type butterfly valve with worm gear

Wafer type butterfly valve with worm gear

operators, to not directly operate the valve based on experience, and check the valve before operation. Open and close signs to avoid losses caused by improper operation. The correct operation method of manual valve is as follows:
1. The operation of manual valve requires the person who manipulates the valve to hold the handle or hand wheel to operate. It is not possible to switch the valve with levers and long wrenches to avoid damage to the handle or hand wheel due to excessive force, let alone violent operation to avoid accidents. happen.
Under normal circumstances, the length of the handle or the diameter of the handwheel is less than 320mm, and only one person is allowed to operate; when the diameter of the handwheel is equal to or greater than 320mm, two people are allowed to complete the operation together, or a single person can appropriately use tools, levers or wrenches. Operate, but pay attention to the lever length not to exceed 0.5m.

manual valve installation site-method

manual valve installation site-method

2. Both manual gate valve and manual stop valve are operated with the help of handwheels. After the valve is fully opened or closed, it must be rotated 1/4 to 1/2 circle to make the threads tightly fit better and avoid the valve at the same time. Overtightening may cause damage.
3. To operate the manual steam valve, preheat the pipe before opening it to discharge the condensed water in the pipe; open the valve slowly to prevent the occurrence of water hammer and cause damage to the valve and pipeline equipment.
4. The sealing surface of the normally open manual valve is easy to stick to impurities and dirt. Before closing and closing, slightly open a slit to allow the high-speed flowing medium to wash away these foreign objects, and then gently close it to improve the sealing effect .
5. In some pipelines with over-temperature medium, when the manual valve is closed, the temperature in the valve body drops, because the thermal expansion and contraction cause the valve to shrink, and there will be some small gaps in the sealing surface, and the valve will leak. In this case, after closing the manual valve, close it again after a while.

The correctness of manual valve operation affects the service life of the valve and even production safety, so it is necessary to master the correct valve operation method. Safe production, start with small things.

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

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Gate valve characteristics and installation notes;
Installation instructions of the wafer type butterfly valve;
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Types and classifications of butterfly valves

Types and classifications of butterfly valves
Butterfly valves can be divided into offset plate type, vertical plate type, inclined plate type and lever type according

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

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

to the structure. According to the sealing form, it is divided into two types: relatively sealed type and hard sealed type. Soft-sealed butterfly valves generally use rubber ring seals, and hard-sealed butterfly valves usually use metal ring seals. According to the connection type, they are divided into flange connection and wafer connection. According to the transmission mode, they are divided into manual, gear transmission, pneumatic, hydraulic and electric. .
Due to the wide variety of butterfly valves, and in special working conditions, the butterfly valve products used are also different. Therefore, for this type of valve, you should choose the type separately from the engineer! According to common types and classifications, butterfly valves can be divided into the following forms:
(1) Classification by structure
1. Center sealing butterfly valve

Types of wafer butterfly valves

Types of wafer butterfly valves

2. Single eccentric sealing butterfly valve
3. Double eccentric sealing butterfly valve
4. Triple eccentric sealing butterfly valve
(2) Classified by link method
1. Wafer butterfly valve
2. Flanged butterfly valve
3. Lug butterfly valve
4. Welded butterfly valve
(3) Classified by working temperature
1. High temperature. t>450 °C butterfly valve.
2. Medium temperature butterfly valve. 120 C<t<450 ℃ butterfly valve.
3. Normal temperature butterfly valve. A butterfly valve of 40C<t<120 °C.
4. Low temperature butterfly valve. One 100<t<一40 °C butterfly valve.
(4) Classified by sealing surface material
1. Soft sealing butterfly valve.
(1) The sealing pair is composed of non-metallic soft material to non-metallic soft material.
(2) The sealing pair is composed of metallic hard materials and non-metallic soft materials.
2. Metal hard sealing butterfly valve. The sealing pair is composed of a metal hard material to a metal hard material.
(5) Classified by work pressure
1. Vacuum butterfly valve, a butterfly valve whose working pressure is lower than the atmospheric pressure of the standard stack.
2. Low pressure butterfly valve, butterfly valve with nominal pressure PN<1.6MPa.
3. Medium pressure butterfly valve, butterfly valve with nominal pressure PN of 2.5-6.4MPa.
4. High-pressure butterfly valve, a butterfly valve with a nominal pressure PN of 10.0-80.0MPa.
5. Ultra-high pressure butterfly valve, butterfly valve with nominal pressure PN>100MPa.
(6) Classified by sealing form

Double offset-lug butterfly valve-D372F-150lbC (1)

Double offset-lug butterfly valve-D372F-150lbC (1)

1. Forced sealing butterfly valve.
(1) Elastic sealing butterfly valve. The specific pressure of the seal is generated by the elasticity of the valve seat or the valve plate when the valve plate squeezes the valve seat when it is closed.
(2) External torque sealing butterfly valve. The seal specific pressure is generated by the torque applied to the valve shaft.
2. Pressure-filled and sealed butterfly valve. The specific sealing pressure is generated by the pressure of the elastic sealing element on the valve seat or valve plate.
3. Automatic sealing butterfly valve. The sealing specific pressure is automatically generated by the medium pressure.
Related knowledge: Types of valves Types of regulating valves Types of stop valves Types of ball valves Types of gate valves

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

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Pneumatic butterfly valve installation instructions

Pneumatic butterfly valve installation instructions and steps
Whether the pneumatic butterfly valve is installed well will affect the efficiency of the equipment. And the maintenance of the pneumatic butterfly valve is also related to the performance of the equipment. Improper installation or lack of maintenance will cause the performance of the butterfly valve to decline, and even unnecessary dangers. The user should check and maintain the pneumatic butterfly valve as scheduled.

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

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

1. Before installation, check that all parts of the pneumatic butterfly valve are not missing, the model is correct, there is no debris in the valve body, and there is no blockage in the solenoid valve and muffler;
2. Put the valve and cylinder in the closed state.
3. Hit the cylinder against the valve (the installation direction is either parallel or perpendicular to the valve body), and then check whether the screw holes are aligned, there will be no too much deviation, if there is a little deviation, just rotate the cylinder body a little. , And then tighten the screws.
4. After installation, debug the pneumatic butterfly valve (the air supply pressure is 0.4~0.6MPa under normal circumstances), and the solenoid valve must be opened and closed manually during the debugging operation (the solenoid valve coil can only be operated manually after the solenoid valve coil is de-energized). Observe the opening and closing of the pneumatic butterfly valve. If the valve is found to be a bit difficult at the beginning of the opening and closing process during the debugging operation, and then it is normal, you need to reduce the stroke of the cylinder (the stroke adjustment screws at both ends of the cylinder should be adjusted inward at the same time, and the valve should be moved to the open position during adjustment. , Then turn off the air source and adjust again) until the valve opens and closes smoothly and closes without leakage. It should also be noted that the adjustable silencer can adjust the opening and closing speed of the valve, but it should not be adjusted too small, otherwise the valve may not operate.
5. Defa should be kept dry before installation, and should not be stored in the open air;
6. Check the pipeline before installing the butterfly valve to ensure that there is no foreign matter such as welding slag in the pipeline;
7. The manual opening and closing resistance of the butterfly valve body is moderate, and the torque of the butterfly valve matches the torque of the selected actuator.
8. The flange specification for butterfly valve connection is correct, and the pipe clamp flange conforms to the

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

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

butterfly valve flange standard. It is recommended to use special flanges for butterfly valves instead of flat welding flanges.
9. Confirm that the flange welding is correct. After the butterfly valve is installed, the flange must not be welded to avoid scalding the rubber parts.
10. The installed pipe flange should be centered and centered with the inserted butterfly valve.
11. Install all the flange bolts and tighten them by hand. It will be confirmed that the butterfly valve and the flange have been aligned, and then the butterfly valve will be opened and closed carefully to ensure flexible opening and closing.
12. Fully open the valve. Use a wrench to tighten the bolts in diagonal order. No washers are needed. Do not overtighten the bolts to prevent serious deformation of the valve ring and excessive opening and closing torque.
Related knowledge: Installation instructions for ventilation butterfly valves; Installation instructions for telescopic butterfly valves

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

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The role and use of the ball valve

The function of the ball valve:
The opening and closing part of the ball valve is a round sphere with a hole. The ball core rotates around the axis of the valve stem by 0-90° back and forth to achieve the purpose of opening or closing the valve. Ball valves have many functions. They are generally used to switch off or adjust the medium in the pipeline. Among them, the three-way ball valve can flexibly cut off, distribute and change the flow direction of the medium. The sealing surface of the ball valve is usually closed with the spherical surface, so it is not easy to be eroded by the medium. It is easy to operate and has a simple and compact structure. It can be used in working conditions such as water, natural gas, acid, and solvent.

fixed ball valve

fixed ball valve

The application of the ball valve:
Ball valves can generally be divided into three categories: floating ball valves, fixed ball valves, and elastic ball valves according to their structure. According to the different sealing performance, it is divided into hard-sealed ball valves and soft-sealed ball valves. The soft-sealed ball valves have better sealing performance and can achieve zero leakage. They are generally used in normal temperature and pressure pipelines with corrosive media, while hard-sealed ball valves are not only It can be used in normal temperature and pressure, as well as pipelines with low temperature and low pressure and high temperature and high pressure.
(1) Floating ball valve
The ball of the floating ball valve is floating and is supported by two valve seats. Under the action of the medium pressure, the ball can produce a certain displacement and tightly adhere to the sealing surface of the valve seat at the outlet end to ensure that the outlet end is sealed. However, if the sphere bears the load of the working medium and is all transmitted to the outlet sealing ring, the sphere may deviate when it is impacted by a higher pressure. Therefore, the ball valve of this structure is generally suitable for normal pressure or low pressure working conditions.
(2) Fixed ball valve

Pneumatic electric high platform ball valve

Pneumatic electric high platform ball valve

The name of the fixed ball valve is that the ball is fixed, and when the valve is closed, the ball valve will not move even if it is pressurized. Fixed ball valves are equipped with a floating seat. After being pressured by the medium, the seat will move so that the sealing ring is pressed tightly on the sphere to ensure sealing. Generally, sliding bearings or rolling bearings are installed on the upper and lower shafts of the ball, which can be operated with a small torque and a small torque, and is generally suitable for high-pressure and large-diameter pipelines.
Other common classifications of ball valves, chip ball valves, orbital ball valves, V-shaped ball valves, O-shaped ball valves, cut-off ball valves, three-way ball valves, four-way ball valves, forged steel ball valves, ash unloading ball valves, anti-sulfur ball valves, eccentric ball valves, thermal insulation ball valves, pneumatic Ball valves, electric ball valves, ferrule ball valves, welded ball valves. Among them, the V-shaped ball valve has a shearing effect, which is especially suitable for media containing fibers, small solid particles, slurry and other media. The three-way ball valve can also be divided into T-type and L-type. The T-shape can make the three intersecting pipelines connect to each other or cut off any one of the channels, playing the role of splitting and merging. The L-shape only connects two perpendicular pipes, and cannot connect to the third pipe at the same time, and it mainly plays a role of distribution.
Related knowledge: working principle of ball valve structure diagram of ball valve.

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

Schematic diagram of electric ball valve structure

The electric ball valve has a simple structure and is composed of a few parts. It has the advantages of small size, light weight, small installation size, small driving torque, easy operation and agility, and it can be quickly opened and closed only by rotating 90°. It has a good flow regulating effect and sealing characteristics; in the application range of large and medium caliber, medium and low pressure, the electric ball valve is one of the leading valves, and it is mainly used to cut off, distribute and change the flow direction of the medium in the pipeline. When the electric ball valve is fully opened, there is no resistance when the medium flows through the ball core port, so the pressure drop that occurs through the valve is very small, so it has better flow control characteristics.

O type ball valve O shaped ball core

O type ball valve O shaped ball core

Electric ball valve structure: There are many types of electric ball valves, which are generally divided into two categories according to different structural forms, namely O-shaped structure and V-shaped structure. The valve ball openings of the two are different, and the application is also different. O-type is generally suitable for shutting off. Use, occasionally adjust, but V-type is more suitable for adjustment (large adjustable ratio).

O-type ball valve structure:
The O-shaped ball valve is equipped with a ball with a middle through hole inside the valve body. A through hole with the same diameter as the pipe diameter is opened on the ball. When it is fully opened, it is a non-block valve with a large flow capacity and no directionality when fluid enters the valve. The sphere can rotate in the sealing seat, and there is a ring-shaped elastic body on both sides of the pipeline direction to achieve sealing. By rotating the ball 90°, the direction of the through hole can be changed, thereby realizing the opening and closing of the ball valve. ,

V-shaped ball valve structure:

V type ball valve, V-shaped ball core

V type ball valve, V-shaped ball core

The V-shaped ball valve core has a V-shaped structure. The valve core is a 1/4 spherical shell with a V-shaped gap. With the rotation of the ball, the opening area changes, but the shape of the opening surface is always triangular, and the flow characteristics are similar. Percentage, the adjustable ratio is large. It has the characteristics of large flow capacity, large adjustable range, shearing force, and tight closing. It is especially suitable for working conditions where fluid materials are fibrous. Generally, V-type ball valves are single-sealed ball valves. Not suitable for bidirectional use.
Related knowledge: The difference between O-shaped ball valve and V-shaped ball valve
Related products: Electric V-shaped ball valve Pneumatic O-shaped ball valve

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

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O type |V type ball valve structure principle;
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Working principle diagram of electric butterfly valve

V-type regulating ball valve

Working principle of pneumatic V-type regulating ball valve
The ball core of the pneumatic V-shaped regulating ball valve is designed with a special V-shaped notch, which has a shearing effect on the valve seat. It is especially suitable for media containing fibers, small solid particles, slurry and other media. According to different structural methods, it can generally be divided into flange and Wafer type; Pneumatic V-type ball valve is a fixed ball valve and also a single-seat sealed ball valve. It has the best adjustment performance among ball valves and can achieve flow adjustment. At the same time, since the valve core and seat are rotated without gaps, they can be wiped by themselves. The fouling on the ball and valve seat keeps a good seal between the ball and the valve seat.

electric V type ball valve

electric V type ball valve

Working principle of pneumatic V-shaped regulating ball valve:
Pneumatic V-shaped regulating ball valve realizes different degrees of proportionality according to the V-shaped angle of the V-shaped sphere. It is generally used in conjunction with a valve positioner to achieve proportional adjustment. The V-shaped spool is most suitable for various adjustment occasions and has a large rated flow coefficient. ,, The pressure loss is small, the use flow capacity is large, and it has accurate shut-off characteristics and control functions. The flow characteristics are approximately equal percentages. The opening and closing parts adopt the V-shaped ball structure, which completely solves the problem of easy deposition of medium in the valve cavity.
Features of pneumatic V-shaped regulating ball valve:
1. Pneumatic V-shaped ball valve V-shaped gap and valve seat produce a strong shear force to cut off impurities such as fibers, and has a self-cleaning function to avoid valve jamming.
2. The pneumatic V-type regulating ball valve has an inherent flow characteristic of approximately equal percentage and an adjustable ratio of up to 300:1, so it can provide precise control in a wide range of changes.

Note: Because the pneumatic V-type regulating ball valve is generally a single-seat sealed ball valve, it is not suitable for two-way use. Due to its streamlined shape and full right-angle rotation control, the maximum volume is extremely high, the flow capacity is particularly large, and the flow resistance is small.

pneumatic V type ball valve

pneumatic V type ball valve

Pneumatic V-type regulating ball valve principle dynamic diagram
The valve core of the pneumatic V-shaped regulating ball valve is designed as a V-shaped gap with a special switch. The V-shaped gap and the valve seat generate a strong shear force, which can cut off high-viscosity media containing fibers or small solid particles, and has a self-cleaning function , To avoid the phenomenon of valve jamming. Pneumatic V-shaped ball valve is suitable for regulation and control, with high stability. Even in the case of small flow or high-viscosity medium, it can also ensure the accuracy of control within the entire range; while O-shaped ball valve is suitable for cutting off, relatively It is economical.
There is a V-shaped opening on the sphere of the pneumatic V-shaped regulating ball valve. As the ball rotates, the opening area changes, but the shape of the opening surface is always triangular. The flow characteristics are approximately equal percentages, the adjustable ratio is large, and the pressure loss is small. The flow capacity is large, and it has accurate interception characteristics and control functions. The opening and closing parts adopt a V-shaped spherical structure, which completely solves the problem of easy deposition of medium in the valve cavity. It is suitable for fibrous and slurry fluids!
The angle of the V-shaped port of the pneumatic V-shaped ball valve can be customized to meet more precise shut-off characteristics and control functions. Generally, more V-shaped valves are used in slurry media. They are similar to cam flex valves and are much better than O-shaped valves. V-shaped ball valves are used as regulating valves. For example, if the medium is not clean, the flow coefficient is low, and the leakage level is high, etc. occasion.

Working principle of electric V-type regulating ball valve

V type ball valve drawing

V type ball valve drawing

The electric V-shaped regulating ball valve has a special-shaped V-shaped incision. When the valve is closed, the V-shaped incision and the valve seat form a wedge shape, which has a shearing effect. The electric V-shaped ball valve is suitable for the control of fibrous slurry, sewage and viscous particle media. It can prevent the seizure of dirt between the ball and the valve seat. It has a self-cleaning function and is a wide-ranging regulating valve.
When the electric V-shaped ball valve rotates, the V-shaped blade of the ball is tangent to the valve seat, thereby cutting off the fiber and solid matter in the fluid. However, the general ball valve does not have this function, so it is easy to cause the fiber impurities to get stuck when closed. , Bring great inconvenience to repair and maintenance. The valve core of the electric V-shaped ball valve will not be jammed by the fiber, and the flow rate of the pipeline medium is adjusted and controlled according to the change of the opening area of ​​the V-shaped gap.
Note: Since the electric V-type regulating ball valve is generally a single-seat sealing ball valve, it is not suitable for two-way use. The integral valve body structure is adopted, and there is no potential for leakage.
Features of electric V-shaped ball valve:
1. It has the advantages of compact structure, small volume, vertical and horizontal installation, etc., adopts movable metal valve seat, self-compensation function, and has superior sealing performance and long service life.
2. The electric V-shaped ball valve adopts a double-bearing structure, which has high mechanical stability and low starting torque, which ensures that the valve has excellent sensitivity and induction speed.
3. Maximum reliability (safety): The valve body is a whole, sturdy and durable, operation is not affected by pipeline pressure, and leakage of the valve body can be avoided.
4. The V-shaped gap and valve seat of the electric V-shaped regulating ball valve produce a strong shearing force to cut off impurities such as fibers, and has a self-cleaning function to avoid valve jamming.
5. Maximum flow volume: Due to the streamlined shape of the electric V-shaped ball valve and the full right-angle rotation control, the maximum volume is particularly high, the flow capacity is particularly large, and the flow resistance is small.

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

related news /knowledge:
O type |V type ball valve structure principle;
The role and classification of valves; 
Pneumatic ball valve-with high platform vs with bracket;
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Butterfly valve flange types and introduction

Butterfly valve flange introduction, butterfly valve flange types
Butterfly valve flanges are called flanges and flanged parts. It is a product that connects valves and pipes in pipelines. The special flanges for butterfly valves are the same as ordinary flanges, that is, the inner hole is different. The special flange of the butterfly valve has a small inner hole and an extra slot for intubation.

flange TG-

flange TG-

The butterfly valve flange can be a single type or a combined type, such as the flanges at both ends of the valve, which is convenient for installing bolts. One end of the pipe and the other end are flange-to-flange connection, or a connection joint, which refers to a foldable connection that is connected to each other by flanges, gaskets and bolts as a set of combined sealing structures. Pipe flanges refer to pipe installations. The flange used in the middle piping, the valve refers to the flange of the valve, the flange has holes, bolts make the two flanges tightly connected, and the flange is sealed with gaskets.
[Butterfly valve flange material] No. 20, A105, Q235A, 12Cr1MoV, 16MnR, 15CrMo, 18-8, 321, 304, 304L, 316, 316L.
[Sealing surface form] Flat surface (FF), raised surface (RF), convex surface (M), concave surface (F), concave and convex surface (MF), tenon surface (T), groove surface (G), tongue and groove surface (TG) , Ring connection surface (RJ).
[According to petrochemical industry standards] Threaded flange (PT), butt welding flange (WN), flat welding flange (SO), socket welding flange (SW), loose flange (LJ), flange cover ( No note).
[According to mechanical industry standards] Butterfly valve flange pictures: Integral flange, butt welding flange, plate flat welding flange, butt welding ring plate loose flange, flat welding ring plate loose flange, flange ring plate loose flange method Lan, flange cover.
[According to national standards] Integral flanges, threaded flanges, butt welding flanges, flat welding flanges with necks, socket welding flanges with necks, butt welding ring loose flanges with necks, plate flat welding flanges, Welded ring plate loose flange, flat welded ring plate loose flange, flanged ring plate loose flange, flange cover.
[According to chemical industry standards] Integral flange (IF), threaded flange (Th), plate flat welding flange (PL), diameter butt welding flange (WN), neck flat welding flange (SO), bearing Insert welding flange (SW), butt welding ring loose flange (PJ/SE), flat welding ring loose flange (PJ/RJ), lining flange cover (BL (S)), flange cover (BL ).
Related products: 7types of flange sealing surface;  Pneumatic flanged butterfly valve

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

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Prevention and treatment of valve corrosion

What is valve corrosion?
Corrosion of the valve is usually understood as the damage to the metal material of the valve under the action of a chemical or electrochemical environment. Since the “corrosion” phenomenon occurs in the spontaneous interaction between the metal and the surrounding environment, how to isolate the metal from the surrounding environment or use more non-metallic synthetic materials is the focus of corrosion prevention. The valve body (including the bonnet) of the valve occupies most of the weight of the valve and is in constant contact with the medium. Therefore, the selection of the valve is often based on the material of the valve body.

The corrosion of the valve body is nothing more than two forms, namely chemical corrosion and electrochemical corrosion. Its corrosion rate depends on the temperature, pressure, chemical properties of the medium and the corrosion resistance of the valve body material. The corrosion rate can be divided into six levels:
1. Complete corrosion resistance: the corrosion rate is less than 0.001 mm/year;
2. Extremely resistant to corrosion: the corrosion rate is 0.001 to 0.01 mm/year;
3. Corrosion resistance: the corrosion rate is 0.01 to 0.1 mm/year;
4. Still corrosion resistant: the corrosion rate is 0.1 to 1.0 mm/year;
5. Poor corrosion resistance: the corrosion rate is 1.0 to 10 mm/year;
6. Not resistant to corrosion: the corrosion rate is greater than 10 mm/year.

How to prevent valve corrosion?
The anti-corrosion of the valve body is mainly based on the correct selection of materials. Although there are abundant anti-corrosion materials, it is not easy to choose the right one, because the problem of corrosion is very complicated. For example, sulfuric acid is very corrosive to steel when the concentration is low, and when the concentration is high, the steel is produced. Passivation film can prevent corrosion; hydrogen only shows strong corrosiveness to steel under high temperature and high pressure. The corrosion performance of chlorine is not great when it is in a dry state, but it is very corrosive when there is a certain humidity, and many materials cannot be used. . The difficulty in selecting valve body materials lies in not only considering corrosion issues, but also factors such as pressure resistance and temperature resistance, whether it is economically reasonable, and whether it is easy to purchase. So it must be attentive.
1. The second is to take lining measures, such as lining lead, lining aluminum, lining engineering plastics, lining natural rubber and various synthetic rubbers. If the media conditions permit, this is an economical method.
Second, again, when the pressure and temperature are not high, the main material of the fluorine-lined valve can often be very effective in preventing corrosion.
3. In addition, the outer surface of the valve body is also corroded by the atmosphere, and generally steel materials are protected by painting.

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

Valve seal (ring) material usage range comparison table

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

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

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Valve seal (ring) material usage range comparison table;
Main application areas of 10 major types of valves;
The difference between American, Germany and China standard valve;
The difference between API, DIN valve and GB valve

Valve selection basis and selection guide

How to select the righty type of valve? the following article will give you an idea how to choose the right structure/type valve.

Nowadays, there are more and more valves on the market, the types of valves are particularly complex, and the

ball valve working diagram-3D GIF animated presentation

ball valve working diagram-3D GIF animated presentation

structures and materials are all different. The selection of valves is very important for the long-term operation of the device in working conditions. Improper selection of valves and users’ ignorance of valves are the source of accidents and safety threats. Nowadays, the demand for valve products in the social industry is becoming more and more extensive, and users should have a further understanding and cognition of knowledge about valves and other aspects.

There are generally two types of valve characteristics, use characteristics and structural characteristics.

Use characteristics of the valve: It determines the main use performance and use range of the valve. The

butterfly valve working diagram-3D GIF animated presentation

butterfly valve working diagram-3D GIF animated presentation

characteristics of the valve use include: valve category (closed circuit valve, regulating valve, safety valve, etc.); product type (gate valve, globe valve, butterfly valve, ball valve) Etc.); the materials of the main parts of the valve (valve body, bonnet, valve stem, valve disc, sealing surface); valve transmission mode, etc.

The structural characteristics of the valve: it determines the structural characteristics of the valve installation, repair, maintenance and other methods. The structural characteristics include: the structural length and overall height of the valve, the connection form with the pipeline (flange connection, threaded connection, clamp Connection, external thread connection, welding end connection, etc.); the form of the sealing surface (inlaid ring, threaded ring, surfacing, spray welding, valve body); valve stem structure (rotating rod, lifting

gate valve working diagram-3D GIF animated presentation

gate valve working diagram-3D GIF animated presentation

rod), etc.

Valve selection steps:
1. Clarify the purpose of the valve in the equipment or device, and determine the working conditions of the valve: applicable medium, working pressure, working temperature, etc.
2. Determine the nominal diameter and connection method of the pipe connected to the valve: flange, thread, welding, ferrule, quick installation, etc.
3. Determine the method of operating the valve: manual, electric, electromagnetic, pneumatic or hydraulic, electrical linkage or electrohydraulic linkage, etc.
4. Determine the material of the valve housing and internal parts according to the medium, working pressure and

globe cut-off valve working diagram-3D GIF animated presentation

globe cut-off valve working diagram-3D GIF animated presentation

working temperature conveyed by the pipeline: gray cast iron, malleable cast iron, ductile iron, carbon steel, alloy steel, stainless acid-resistant steel, copper alloy, etc.
5 Select the type of valve: closed circuit valve, regulating valve, safety valve, etc.
6. Determine the valve type: gate valve, globe valve, ball valve, butterfly valve, throttle valve, safety valve, pressure reducing valve, steam trap, etc.
7. Determine the parameters of the valve: For automatic valves, first determine the allowable flow resistance, discharge capacity, back pressure, etc., according to different needs, and then determine the nominal diameter of the pipeline and the diameter of the valve seat hole.
8. Determine the geometric parameters of the selected valve: structural length, flange connection form and size, valve height dimension after opening and closing, connecting bolt hole size and number, overall valve outline size,

tilting disc swing check valve working diagram-3D GIF animated presentation

tilting disc swing check valve working diagram-3D GIF animated presentation

etc.
9. Use existing information: valve product catalog, valve product sample, etc. to select appropriate valve products.

Basis for valve selection:
1. The purpose, operating conditions and operation control mode of the selected valve.
2. The nature of the working medium: working pressure, working temperature, corrosion performance, whether it contains solid particles, whether the medium is toxic, whether it is flammable or explosive medium, the viscosity of the medium, etc.
3. Requirements for valve fluid characteristics: flow resistance, discharge capacity, flow characteristics, sealing level, etc.
4. Requirements for installation dimensions and external dimensions: nominal diameter, connection to the pipeline and connection dimensions, external dimensions or weight restrictions, etc.
5. Additional requirements for the reliability and service life of valve products and the explosion-proof performance of electric devices. (Note when selecting parameters: If the valve is to be used for control purposes, the following additional parameters must be determined: operation method, maximum and minimum flow requirements, pressure drop for normal flow, pressure drop when closed, maximum and minimum inlets of the valve Pressure.)

According to the above-mentioned basis and steps for selecting valves, the internal structure of various types of valves must be understood in detail when selecting valves reasonably and correctly, so that the correct choice can be made on the preferred valve. The ultimate control of the pipeline is the valve. The valve opening and closing parts control the flow mode of the medium in the pipeline. The shape of the valve flow channel makes the valve have a certain flow characteristic. This must be considered when selecting the most suitable valve for the pipeline system.