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Description and classification of valve connection

Classification and description of valve connection methods: Nowadays, the application range of valves is wider and

double flange butterfly valve body

double flange butterfly valve body

wider, and corresponding valves should be used in different environments. The connection between the entire valve and the pipeline or equipment is different. Regardless of installation, use and maintenance, attention should be paid to the improper connection of the valve, which may cause the valve to run, leak, drip, and leak. Therefore, valve users should be treated in accordance with the situation of the user.
There are many types of valve connection. Common valve connection methods are: flange connection, butt connection, butt welding connection, thread connection, ferrule connection, clamp connection, self-sealing connection and other connection forms. This article will focus on the most common flange connection, butt welding connection and threaded connection in the installation process easy to explain the problems, I hope to help everyone.

Threaded valve: A simple connection method, often used for small valves. This connection is usually made by processing the valve inlet and outlet ends into tapered pipes or straight pipe threads, which can be connected to tapered pipe threaded joints or pipelines. Since this connection may have large leakage channels, sealants, sealing tape or fillers can be used to plug these channels. If the material of the valve body can be welded, but the expansion coefficient is very different, or the working temperature has a large range of variation, the threaded connection must be honey sealed. Threaded valves are mainly valves whose nominal diameter is below 50mm. If the diameter size is too large, the installation and sealing of the connection part will be very difficult. In order to facilitate the installation and removal of threaded valves, pipe joints can be used at appropriate positions in the pipeline system. Valves with a nominal diameter below 50mm can use pipe sockets as pipe joints, and the thread of the pipe socket connects the two connected parts together. …
Flanged valve: Flanged valve, the most used connection form among valves. Its installation and disassembly are relatively convenient. But it is heavier than the threaded valve, and the corresponding price is higher. Therefore, it is suitable for pipe connections of various diameters and pressures. However, when the temperature exceeds 350 degrees, the bolts, gaskets and flanges become loose, and the load of the bolts is significantly reduced, which may cause leakage to the flange connection with a large force.
Welded valve This connection is suitable for various pressures and temperatures, and is more reliable than flanged connections when used under heavy load conditions. However, it is difficult to disassemble and reinstall the valve connected by welding, so its use is limited to the occasions that usually can operate reliably for a long time, or where the use conditions are heavy and the temperature is high. Such as the pipelines of thermal power stations, nuclear power projects, and ethylene projects. Welded valves with a nominal diameter of less than 50mm usually have welding sockets to accept the pipeline at the end of the load. Since socket welding forms a gap between the socket and the pipe, it is possible that the gap will be corroded by some media. At the same time, the vibration of the pipe will fatigue the connection part, so the use of socket welding is limited. In the occasions where the nominal diameter is large, the use conditions are heavy, and the temperature is high, the valve body is often welded with grooves. At the same time, there are original requirements for the welding seam, and a skilled welder must be selected to complete this work.

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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Commonly used valve body material code description;
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Raised face flange and concave and convex face flange

Flange is used for the connection between two devices. The abbreviation refers to the form of the sealing surface. There are holes on it. The two flanges are connected by bolts. It is generally used for The mutual connection between

flanges

flanges

the shaft and the shaft is also used for the connection between the pipe ends; it is a detachable connection of a set of combined sealing structures that are connected by flanges, gaskets and bolts. The thickness of flanges with different pressures is different, and their use forms are also different.

Commonly used butterfly valves include wafer butterfly valves and flange butterfly valves. Wafer type butterfly valve uses double-head bolts to connect the valve between two pipe flanges. Flange type butterfly valve has flanges on the valve, and the two ends of the valve are flanged to the pipe flanges with bolts.
For the most common raised face flanges and concave and convex face flanges, in the flange connection, the raised face flange needs to be matched with the concave face flange, commonly known as one male and one female, and the raised face flange should be matched with the raised face flange. Generally speaking, raised face flanges should also be a kind of flat flanges, code-named RF, and the RF face can only be linked with the RF face. The code name of the raised face flange is M, and the M face flange needs to be connected with the FM face. One is female FM (Female Male), and the other is male M (Male). The pressure on the M/FM side is better than that on the RF side. Raised face flanges and raised face flanges are used in pairs, and the code name is RF. The comparison chart of the two is as follows:

RF, MFM flanges

RF, MFM flanges

The angle between the sealing surface of the raised face flange and the flange bolt connection surface is 45°, and the sealing surface of the concave and convex flange and the flange bolt connection surface are 90° angle, that is, the two sides are perpendicular .

Raised face flanges are more commonly used in the market, and generally there is no problem below 2.5MPa. Concave-convex flanges are more expensive and have better sealing effect, so the applicable pressure level is higher. When designing, it is more troublesome. For example, when you mention the equipment condition diagram, you must indicate what type of method it is. Lan, and then when the statistics take over the material, it is another matching flange.

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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Comparison table of valve diameter and medium flow rate

It is well known that the flow rate and flow rate of the valve mainly depend on the diameter of the valve, and also

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

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

related to the resistance of the valve structure to the medium. At the same time, it has a certain internal connection with various factors such as the valve pressure, temperature and medium concentration. The flow channel area of ​​the valve has a direct relationship with the flow rate and flow rate, and the flow rate and flow rate are two mutually dependent quantities. When the flow rate is constant, the flow rate is large, the flow channel area can be smaller; the flow rate is small, the flow channel area can be larger. On the contrary, the flow channel area is large, its flow velocity is small; the flow channel area is small, its flow velocity is large.
1. The flow rate of the medium is large, and the valve diameter can be smaller, but the resistance loss is large and the valve is easily damaged. If the flow velocity is large, it will have electrostatic effect on flammable and explosive media, causing danger; the flow velocity is too small, the efficiency is low and it is not economical. For the medium with high viscosity and explosive, the flow rate should be smaller. The flow rate of oil and liquid with high viscosity is selected according to the viscosity, generally 0.1~2m/s.
2. In general, the flow rate is known, and the flow rate can be determined by experience. The nominal diameter of the valve can be calculated through the flow rate and flow rate.
3. The valve diameter is the same, its structure type is different, and the fluid resistance is also different. Under the same conditions, the larger the resistance coefficient of the valve, the more the flow rate and flow rate of the fluid through the valve will drop; the smaller the valve resistance coefficient, the less the flow rate and flow rate of the fluid through the valve will drop.
The common flow rates of various media are shown in the following table:

liquid type use condition speed m/s
satuated vapor DN>200 30-40
DN=200-100 25-35
DN<100 15-30
superheated steam DN>200 40-60
DN=200-100 30-50
DN<100 20-40
low pressure steam P<1.0 (absolute pressure) 15-20
midium pressure steam P=1.0-4.0 (absolute pressure) 20-40
high pressure steam P=4.0-12.0 (absolute pressure) 40-60
compressed air vaccum 5-10
P≤0.3 (instrument pressure) 8-12
P=0.3-0.6 (instrument pressure) 10-20
P=0.6-1.0 (instrument pressure) 10-15
P=1.0-2.- (instrument pressure) 8-12
P=2.0-3.0 (instrument pressure) 3-6
P=3.0-30.0 (instrument pressure) 0.5-3
Oxygen P=0-0.05 (instrument pressure) 5-10
P=0.05-0.6 (instrument pressure) 7-8
P=0.6-1.0 (instrument pressure) 4-6
P=1.0-2.0 (instrument pressure) 4-5
P=2.0-3.0 (instrument pressure) 3-4
gas 2.5-15
semi-water gas P=0.1-0.15 (instrument pressure) 10-15
natural gas 30
Nitrogen P=5.0-10.0 (absolute pressure) 15-25
Ammonia vaccum 15-25
P<0.3 (instrument pressure) 8-15
P<0.6 (instrument pressure) 10-20
P≤2 (instrument pressure) 3-8
Acetylene water 30
5-6
Acetylene gas P<0.01 (instrument pressure) 3-4
P<0.15 (instrument pressure) 4-8
P<0.25 (instrument pressure) 5
chlorine  gas 10-25
liquid 1.6
Hydrogen chloride  gas 20
liquid 1.5
liquid ammonia vaccum 0.05-0.3
P≤0.6 (instrument pressure) 0.3-0.8
P≤2.0 (instrument pressure) 0.8-1.5
Sodium hydroxide concentration 0-30% 2
concentration 30-50% 1.5
concentration 50-73% 1.2
Sulfuric acid concentration 88-93% 1.2
concentration 93-100% 1.2
hydrochloric acid 1.5
water and other similar viscosity liquid P=0.1-0.3 (instrument pressure) 0.5-2
P≤1.0 (instrument pressure) 0.5-3
P≤8.0 (instrument pressure) 2-3
P≤20-30 (instrument pressure) 2-3.5
Heating network circulating water Cooling water 0.3-1
pressure backwater 0.5-2
pressureless backwater 0.5-1.2
tap water main pipe P=0.3 (instrument pressure) 1.5-3.5
sub pipe P=0.3 (instrument pressure) 1-1.5
boiler feed water >3
steam condensate 0.5-1.5
condensate free flow 0.2-0.5
superheated water 2
seawater and brackish water P<0.6 (instrument pressure) 1.5-2.5

Note: The unit of DN value is mm; the unit of P value is MPa.
for example:
The resistance coefficient of the gate valve is small, only in the range of 0.1 to 1.5; the resistance coefficient of the large diameter gate valve is 0.2 to 0.5; the resistance coefficient of the narrow gate valve is larger.
The resistance coefficient of the stop valve is much larger than that of the gate valve, generally between 4 and 7.
The resistance coefficient of the Y-type globe valve (DC type) is small, between 1.5 and 2; the resistance coefficient of the forged steel globe valve is large, even as high as 8.
The resistance coefficient of the check valve depends on the structure: the swing check valve is usually about 0.8-2, among which the multi-leaf swing check valve has a large resistance coefficient; the lift check valve has a large resistance coefficient, up to 12 .
The resistance coefficient of the plug valve is small, usually about 0.4 to 1.2.
The resistance coefficient of the diaphragm valve is generally around 2.3.
The drag coefficient of butterfly valve is small, generally within 0.5. The resistance coefficient of the ball valve is small, generally around 0.1.
Note: The resistance coefficient of the above valve is the value when the valve is fully opened. The selection of valve diameter should take into account the machining accuracy and dimensional deviation of the valve, as well as other factors. The valve diameter should have a certain margin, generally 15%. In actual work, the valve diameter depends on the diameter of the process pipeline.

Related products: wafer butterfly valve; lug butterfly valve; double flange butterfly valve;
Double eccentric 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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Valve flow characteristic curve and classification;
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Principles of valve selection in the petroleum and chemical industry

Faced with so many valve classifications and such complex various working conditions, to choose the most suitable

lug type butterfly valve, ductile iron, center lined,

lug type butterfly valve, ductile iron, center lined,

valve product for piping system installation, you should first understand the characteristics of the valve; secondly, you should master the steps and basis for selecting the valve; and then you should follow the choice of oil , The principle of valves used in the chemical industry. The principle of selecting valves in the petroleum and chemical industries: the flow path is a straight-through valve, and its flow resistance is small, and it is usually selected as a shut-off and open medium valve; a valve that is easy to adjust the flow is used as a control flow; a plug valve and a ball valve are more suitable Used for reversing and shunting; the sliding of the closing part along the sealing surface of the valve with wiping effect is most suitable for the medium with suspended particles.

1. Valves for shut-off and open media: The flow channel is a straight-through valve with low flow resistance. It is usually selected as a valve for shut-off and open media. The downward closing valve (stop valve, plunger valve) is less used because of its tortuous flow path and higher flow resistance than other valves. Where higher flow resistance is allowed, a closed valve can be used.

Globe valve (9)

Globe valve (9)

2. Valves used for flow control: Generally, valves that are easy to adjust flow are selected as flow control valves. Downward closing valves (such as globe valves) are suitable for this purpose because the size of its seat is proportional to the stroke of the closing member. Rotary valves (plug valves, butterfly valves, ball valves) and flex-body valves (pinch valves, diaphragm valves) can also be used for throttling control, but they are usually only applicable in a limited range of valve diameters. The gate valve uses a disc-shaped gate to cross-cut the circular valve seat port. It can only control the flow better when it is close to the closed position, so it is usually not used for flow control. 3. Valves for reversing and shunting According to the needs of reversing and shunting, this kind of valve can have three or more channels. Plug valves and ball valves are more suitable for this purpose. Therefore, most of the valves used for reversing and splitting use one of the plug valves and ball valves. However, in some cases, other types of valves can also be used for reversing and shunting as long as two or more valves are properly connected to each other.

4. Valves for medium with suspended particles When there are suspended particles in the medium, it is most suitable for valves with a wiping effect on the sliding of the closing part along the sealing surface. If the back and forth movement of the closing member to the valve seat is vertical, it may hold particles. Therefore, unless the sealing surface material allows particles to be embedded, this valve is only suitable for basic clean media. Ball valves, plug valves, and butterfly valves have a wiping effect on the sealing surface during opening and closing, so they are suitable for use in media with suspended particles.

At present, no matter in the pipeline system of petroleum, chemical industry, or other industries, valve applications, operating frequencies and services are ever-changing. To control or eliminate even low-level leakage, the most important and critical equipment is still valves. The ultimate control of the pipeline is the valve. The service and reliable performance of the valve in various industries are unique.

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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Chinese marine valve product standard encyclopedia

Marine valves are equipment used to control the pressure, flow and flow direction of fluids in marine pipelines to

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

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

meet the environmental conditions of ships. A valve is a control device for a fluid pipeline. Its basic function is to connect or cut off the flow of the pipeline medium, change the flow of the medium, change the flow direction of the medium, adjust the pressure and flow of the medium, and protect the normal operation of the pipeline equipment.

GB/T 584 Marine flange cast steel globe valve; GB/T 585 Marine flange cast steel globe check valve; GB/T 586 Marine flange cast steel check valve; GB/T 587 Marine flange bronze globe valve GB /T; 588 marine flange bronze check valve; GB/T 589 marine flange bronze check valve; GB/T 590 marine flange cast iron stop valve; GB/T 59 industrial marine flange cast iron stop check valve; GB/T 592 Marine flange cast iron check valve; GB/T 593 Marine flange bronze and cast iron packing cock; GB/T 594 Marine external thread forged steel globe valve; GB/T 595 Marine external thread bronze globe valve; GB/ T 596 Marine externally threaded bronze check valve; GB/T 597 Marine externally threaded bronze check valve GB/T 598 Marine externally threaded bronze packing cock; GB/T 599 Marine externally threaded bronze discharge cock; GB/T 1241 Marine External thread forged steel stop check valve; GB/T 1850 marine external thread heavy block quick closing valve; GB/T 1852 marine flange cast steel steam pressure reducing valve; GB/T 1853 marine flange cast steel side stop stop Return valve; GB/T 1854 marine flanged cast iron single-row suction stop valve box; GB/T 1855 marine flanged cast iron single-row suction stop check valve box; GB/T 1856 marine flanged cast iron single-row discharge stop valve box; GB/T 1951 Marine low-pressure male-threaded bronze stop valve; GB/T 19 52 Marine low-pressure male-threaded bronze check valve; GB/T 1953 Marine low-pressure male-threaded bronze stop check valve GB/T 2029 Cast steel suction sea valve; GB /T 2030 Bronze suction sea valve; CB/Z 800-2004 GB/T 2032 Marine flanged fire hydrant; GB/T 2499 Marine flanged cast iron double-row globe valve box; GB/T 3036 Marine central butterfly valve; GB/T 3037 Marine double eccentric butterfly valve; GB/T 5744 marine quick closing valve; GB/T 11691 cast steel suction sea valve (four position); GB/T 11692 bronze suction sea valve (four position); GB/T 11696 marine cast steel vertical valve -Shaped check valve; CB/T 304 flanged cast iron right angle safety valve; CB/T 309 marine internal threaded bronze globe valve; CB/T 310 marine internal threaded bronze straight-through check valve; CB/T 311 marine internal threaded bronze packing cock CB 312 pressure gauge valve; CB/T 465 flanged cast iron gate valve CB/T 466 flanged cast steel gate valve CB/T 467 flanged bronze gate valve CB 541 external thread aluminum alloy packing three-way plug CB 557 bronze stop check discharge valve CB 558Pgl 60 male threaded brass air quick start valve CB 561pgl 60 air bottle stop valve CB 563 male threaded aluminum alloy right angle stop valve CB/T 569 marine PM 60 male thread bronze air stop valve CB/T 569 marine PM 60 male thread bronze air stop valve CB 583 flange brass four-way plug CB 584 with check valve high pressure air right angle shut-off valve specification CB 585 with bottom flange right angle blow-off valve CB 587 brass sea valve CB 588 Pg250 diaphragm air right angle shut-off valve CB 589 with Specification for high pressure air right angle shut-off valve with mounting plate CB 590 Specification for high pressure air right angle shut-off valve with mounting plate CB 591 Specification for high pressure air right angle check valve CB 592 with bottom flange Specification for high pressure air right angle shut-off valve CB 593 with bottom flange Specification for high-pressure air right-angle cut-off check valve CB 594 Air right-angle quick-opening valve CB 595 Pg200 air right-angle throttle valve CB 596 Male threaded steel right-angle stop valve CB 597 Male threaded steel right-angle stop check valve CB 598 with bottom flange Male threaded bronze right-angle globe valve CB/T 601 Self-closing drain valve CB/T 624 Water pressure reducing valve CB/T 627 Impact flange cast steel cut-off check valve CB 852 Pg250 Male threaded bronze air straight-through globe valve CB 853 P30 flange cast steel globe valve CB 854 P30 flange bronze globe valve CB 855 P30 flange bronze globe valve CB 898 blowdown side valve CB 900 vertical check valve CB 901 P30 flange bronze gate valve CB 905 emergency tongue Valve CB 907 Male threaded bronze right-angle liquid safety valve CB 909 Angle flap valve CB 1010 Male threaded stainless steel globe valve CB 1049 Double-sided drive emergency side valve CB 3022 Male threaded air signal safety valve CB/T 30 87 flanged cast steel right-angle sea Valve CB 3107 Marine auxiliary boiler feed water stop check valve CB 3124 Pg16 internal thread bronze gate valve CB/T 3191 High pressure manual ball valve CB 3192 external thread steam bronze right-angle safety valve CB/T 3196 flange cast steel seawater stop valve CB/T 3197 method Blue Cast Steel Seawater Stop It Back Valve CB/T 3265 Liquid Level Gauge Self-closing Valve CB 3297 Bellows Type Traps CB/T 3475 Anti-wave Valve CB/T 3476 Vertical Anti-wave Valve CB/T 3477 Closable Vertical Anti-closing Valve Wave valve CB/T 3478 flange suction check valve CB/T 35 91 flange ductile iron tanker gate valve CB/T 3656 marine air pressure reducing valve CB/T 3819 plate lr_E valve CB/T 3841 side Side boiler relief valve CB/T 3843 pressure relief 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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Reasons and solutions for leakage of valve sealing surface

The valve is the most used control component in the fluid system. It can be used to switch or control the flow

U-type-flange-butterfly-valve-2

U-type-flange-butterfly-valve-2

direction and adjust the function. From the simplest cut-off function, the valve is sealed in the machine. Its function is to prevent the medium from In the cavity where the part is located, the joint between the parts leaks outward or prevents external substances from entering the inside. The collar and parts that play a sealing role are called seals or sealing structures, or seals for short. The two joint surfaces are in contact with the seal and play a sealing role. The surface is called the sealing surface. The valve sealing surface is the core part of the valve, and its leakage can generally be divided into the following types, namely, leakage of the sealing surface, leakage at the joint of the sealing ring, leakage caused by the fall of the closure member, and leakage of foreign objects embedded between the sealing surfaces. One of the most extensive uses of valves in pipelines and equipment is to cut off the flow of media. Therefore, its tightness is the main factor that determines whether internal leakage occurs. The valve sealing surface is generally composed of a pair of sealing pairs, one on the valve body and the other on the disc.

The reasons for the leakage of the sealing surface are generally as follows:
1. The sealing surface is unevenly ground and cannot form a tight line;
Second, the top center of the connection between the valve stem and the closing member is suspended, incorrect or worn;
3. The valve stem is bent or incorrectly assembled, which makes the closing part skewed or out of alignment;
4. Improper selection of the sealing surface material or failure to select the valve according to the working conditions, the sealing surface is prone to corrosion, erosion and wear;
5. Surfacing and heat treatment are not operated in accordance with the regulations, due to low hardness, wear, corrosion due to burning of alloy elements, and cracks due to excessive internal stress;
Six, the sealing surface after the surface treatment peels off or loses its original performance due to excessive grinding; Seven, the sealing surface is not tightly closed or the crevices appearing due to cold shrinkage after closing, resulting in intermediate corrosion; Eight, treat the shut-off valve as When the throttle valve and pressure reducing valve are used, the sealing surface is eroded and damaged;
9. The valve has reached the fully closed position and continued to apply excessive closing force, including incorrect use of long levers, and the sealing surface was crushed and deformed;
10. Excessive wear of the sealing surface causes disconnection, that is, the sealing pair cannot be tightly sealed;

Prevention and elimination methods of valve sealing surface leakage:
1. When grinding the sealing surface, the grinding tools, abrasives, emery cloth, sandpaper and other objects should use a reasonable grinding method to be correct, and color inspection should be carried out after grinding. The sealing surface should be free of indentation, cracks, scratches and other defects;
2. The connection between the valve stem and the closing member should meet the design requirements. If the top center does not meet the requirements, it should be trimmed. The top center should have a certain movable clearance, especially the axial gap between the valve stem shoulder and the closing member should not be less than 2 Mm;
3. The bend of the valve stem should be straightened. After the valve stem, stem nut, closing parts and valve seat are adjusted, they should be on a common axis;
Fourth, when selecting a valve or replacing the sealing surface, it should meet the working conditions. After the sealing surface is processed, its corrosion resistance, resistance and scratch resistance should be good;
5. The surfacing welding and heat treatment process should meet the technical requirements of the regulations and specifications. After the sealing surface is processed, the acceptance should be carried out. No defects that affect the use are allowed;
Six, the sealing surface surface firing, nitriding, shed infiltration, plating and other processes must be carried out in strict accordance with the technical requirements of its regulations and specifications. The penetration layer of the sealing surface should not exceed one-third of this layer to damage the plating and penetration layer. In serious cases, the plating layer and penetration layer should be removed and the surface treatment should be performed again. The sealing surface of the surface with high frequency smashing can be repeatedly fired and repaired;
Seven, the valve should be marked when it is closed or opened, and it should be repaired in time if the valve is not tightly closed. For high-temperature valves, some slits that appear to be cold-shrinked after closing should be closed more than once at a certain interval after closing;
8. The valve used as a shut-off valve is not allowed to be used as a throttle valve or a pressure reducing valve. The closing part should be in the fully open or fully closed position. When the flow and pressure of the medium need to be adjusted, the throttle valve and reducing valve should be set separately. Pressure valve;
9. The front opening and closing of the valve should comply with the section “Operation of the valve”. The closing force of the valve is appropriate. The diameter of the handwheel is less than 320mm. Only one person is allowed to operate. For handwheels with a diameter equal to or greater than 320mm, two persons or one person are allowed to operate. Operate with leverage within 500 mm;
10. After the waterline drops, it should be adjusted, and the sealing surface that cannot be adjusted should be replaced;

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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Description of electric valve connection

Electric valve wiring methods are classified according to different use requirements and different field conditions,

lug type butterfly valve, ductile iron, center lined,

lug type butterfly valve, ductile iron, center lined,

and the wiring methods used by electric actuators with different functions are also different. The user should have an understanding of the relevant knowledge of the wiring, so as to avoid unnecessary failures. On the one hand, the entire circuit will be short-circuited; On the other hand, it may cause huge economic losses caused by the burning of the machine, or even more serious Accident!

Electric valve actuators can generally be divided into AC (AC110V, AC220V, AC380V) and DC (DC24V, DC12V) according to the power supply voltage. According to the control method, they can be divided into active switch type, passive switch type, potentiometer type, explosion-proof type, and adjustable type Wait. (Related products: Electric switching butterfly valve, Electric regulating butterfly valve, Electric switching ball valve, Electric regulating ball valve)

Active switch type, common switch type with source indicator wiring diagram

Active switch type, common switch type with source indicator wiring diagram

Passive switch type, switch type passive contact type with feedback wiring diagram

Passive switch type, switch type passive contact type with feedback wiring diagram

Opening type potentiometer type, switch type with opening type wiring diagram

Opening type potentiometer type, switch type with opening type wiring diagram

Intelligent adjustment type, input and output 4-20mA, intelligent adjustment type wiring diagram

Intelligent adjustment type, input and output 4-20mA, intelligent adjustment type wiring diagram

AC 380V, with passive contact feedback, 380V power supply wiring diagram

AC 380V, with passive contact feedback, 380V power supply wiring diagram

DC24V, exchange of positive and negative switches and passive signal feedback, 24V power supply wiring diagram

DC24V, exchange of positive and negative switches and passive signal feedback, 24V power supply wiring diagram

Note: The above circuit diagram is for reference only, the actual circuit diagram attached to the product shall prevail. In addition, the electric devices of each manufacturer are different, and the wiring methods are also different. Please do not perform operations based on this standard. If a series of problems or related accidents occur, our company will not be responsible. !

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 actuator / actuation -(4)-angle stroke valve actuator application

Angle stroke valve actuator application products:

1. Butterfly valve:
The baffle of the butterfly valve controls the flow of fluid with the rotation of the shaft. It is composed of valve body, baffle, baffle shaft and shaft seal. Its simple structure, small size, light weight, low cost and large flow capacity are especially suitable for occasions with low pressure difference, large diameter, large flow gas and fluid with su

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

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

spended solids, but the leakage is large. Its flow characteristics are achieved at the corners. The front and equal percentage characteristics are similar, but the work will be unstable and the characteristics will not be good in the future; use in the corner range. Butterfly valves are not only widely used in general industries such as petroleum, gas, chemical, and water treatment, but also used in cooling water systems of thermal power stations.

2. Ball valve:
The ball valve is defined in the standard GB/T21465-2008 “Valve Terminology” as a valve in which the opening and

closing part (sphere) is driven by the valve stem and rotates around the axis of the valve stem. The ball valve has a 90-degree rotation. The cock body It is a sphere with a circular through hole or channel passing through its axis. It is mainly used to cut off or connect the medium in the pipeline, and can also be used for fluid adjustment and control. Among them, the hard-sealed V-shaped ball valve has a strong shear between the V-shaped core and the metal seat of the hard alloy. Shearing force is especially suitable for media containing fibers and tiny solid particles. The multi-way ball valve can not only flexibly control the confluence, divergence, and flow direction switching of the

14 ball-valve-6

14 ball-valve-6

medium in the pipeline, but also close any channel and connect the other two channels. This type of valve should generally be installed horizontally in the pipeline. Ball valve classification: pneumatic ball valve, electric ball valve, manual ball valve. The ball valve can be closed tightly with only a 90-degree rotation and a small torque. The ball valve is most suitable for use as a switch and shut-off valve, V-shaped ball valve. In the developed western countries, the use of ball valves is increasing year by year. In our country, ball valves are widely used in petroleum refining, long-distance pipelines, chemicals, papermaking, pharmaceuticals, water conservancy, electric power, municipal administration, steel and other industries. Occupy a pivotal position in the national economy.

3. Cam flex valve:

Cam flex valve, also known as eccentric rotary valve, is also a new-type regulating valve. The center line of the spherical valve core deviates from the center of the rotating shaft, and the rotating shaft drives the valve core to rotate eccentrically, so that the valve core enters the valve seat forward and downward.

The eccentric rotary valve has the advantages of small size, light weight, reliable use, convenient maintenance, strong versatility, and low fluid resistance. It is suitable for occasions with high viscosity and has good performance in lime, mud and other fluids.

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:

Types and working principles of electric valves;
Pneumatic ball valve principle, structure and working principle;
The working principle of butterfly valve (picture);
Characteristics and working principle of electric globe valve

What is the material of Bolts and nuts of Valve Stem?

Bolts and nuts material of valve stem:

bolts and nuts for butterfly valve

bolts and nuts for butterfly valve

The stem nut directly bears the axial force of the stem during the opening and closing of the valve, so it must have a certain strength. At the same time, it and the valve stem are threaded transmission, which requires a small friction coefficient, no rust and avoid seizure.

1. Copper alloy Copper alloy has a small friction coefficient and does not rust. It is one of the commonly used materials. For low pressure valves with Pg<1.6Mpa, ZHMn58-2-2 cast brass can be used. ZQAL9-4 Wuxi bronze can be used for Pg16-6.4Mpa medium pressure valve. For high-pressure valves, ZHAL66-6-3-2 cast brass can be used.

2. Steel When the working conditions do not allow the use of copper alloys, high-quality carbon steels such as 35 and 40 can be selected, and stainless acid-resistant steels such as 2Cr13, 1Cr18Ni9, and Cr17Ni2 can be used. Working conditions are not allowed to refer to the following situations.

1. For electric valves, stem nuts with melon clutches need heat treatment to obtain high hardness or surface hardness.

2. When the working medium or the surrounding environment is not suitable for copper alloy, such as ammonia medium that corrodes copper. When selecting steel stem nuts, pay special attention to thread seizure.

Tianjin Tanghai Valve Manufacturing Co., Ltd. is one of the largest valve bolts and nuts manufacturers in China, main products are butterfly valves, check valves, gate valve and globe valves. Key words:  butterfly valve, lug type butterfly valve, wafer type butterfly valve, U-type butterfly valve, double flange butterfly valve, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…)

What is the material of the butterfly valve stem?

Stem material classification:
During the opening and closing of the butterfly valve, the valve stem bears the forces of tension, pressure and

buttefly valve stem shaft parts (6)

buttefly valve stem shaft parts (6)

torsion, and is in direct contact with the medium. At the same time, there is relative frictional movement with the packing. Therefore, the valve stem material must ensure that there is enough at the specified temperature Strength and impact toughness, a certain degree of corrosion resistance and scratch resistance, and good manufacturability. The commonly used stem materials are as follows.

1. When carbon steel is used in water and steam medium with low pressure and medium temperature not exceeding 300℃, A5 ordinary carbon steel is generally used. When used in water and steam medium with medium pressure and medium temperature not exceeding 450℃, 35 high-quality carbon steel is generally used.

2. When alloy steel is used for medium pressure and high pressure, and the medium temperature does not exceed 450 ℃ water, steam, petroleum and other media, 40Cr (chromium steel) is generally used. 38CrMoALA nitriding steel can be used when it is used in water, steam and other media with high pressure and medium temperature not exceeding 540℃. 25Cr2MoVA chromium molybdenum vanadium steel is generally used when used in high pressure steam medium with medium temperature not exceeding 570℃.

3. Stainless acid-resistant steel S is used for non-corrosive and weakly corrosive media with medium and high pressure and medium temperature not exceeding 450℃. 1Cr13, 2Cr13, 3Cr13 chromium stainless steel can be selected. When used in corrosive media, stainless acid-resistant steel such as Cr17Ni2, 1Cr18Ni9Ti, Cr18Ni12Mo2Ti, Cr18Ni12Mo3Ti, and PH15-7Mo precipitation hardening steel can be selected.

4. When heat-resistant steel is used for high-temperature valves whose medium temperature does not exceed 600℃, 4Cr10Si2Mo martensitic heat-resistant steel and 4Cr14Ni14W2Mo austenitic heat-resistant steel can be selected.

Tianjin Tanghai Valve Manufacturing Co., Ltd. is one of the largest valve stem/shaft manufacturers in China, main products are butterfly valves, check valves, gate valve and globe valves. Key words:  butterfly valve, lug type butterfly valve, wafer type butterfly valve, U-type butterfly valve, double flange butterfly valve, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…)