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The structure and connection of the American standard valve

American standard valves mainly have API and ASME standards. ASTM and ASTM are material standards; valves designed, manufactured, produced and tested according to American standards are called American standard valves.
The American standard valve is a control component in the fluid conveying system. It has the functions of cut-off, regulation, diversion, prevention of reverse flow, voltage stabilization, diversion or overflow and pressure relief; the valve used in the fluid control system is cut off from the simplest American standard. There are many types and specifications of American standard valves used in extremely complex automatic control systems. Valves can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, mud, oil, liquid metal and radioactive media. Valve types: gate valve, knife gate valve, check valve, butterfly valve and others.

The structure types:

code structure type explaination standard face to face
C BB-BG-OS&Y bolted bonnet, bolted gland, outside screw & yoke API602/API602M ASME B16.10
D BB-BG-OS&Y bolted bonnet, bolted gland, outside screw & yoke API603/API603M ASME B16.10
E BB-BG-OS&Y-N bolted bonnet, bolted gland, outside screw & yoke-needle type API602M ASME B16.10
G BC-PISTON-LIFT (BOLTED BONNE,PISTON-LIFT) API602M ASME B16.10
H BC-PISTON-LIFT (BOLTED BONNE,PISTON-LIFT) outside screw & yoke API603M ASME B16.10
B BB-BG-OS&Y-W BOLTED BONNET,BOLTED GLAND,OS&Y ,BELLOWS SEAL TYPE) API600M ASME B16.10
L BB-BG-OS&Y-L BOLTED BONNET,BOLTEDGLAND ,OS&Y ,CRYOGENIC SERVICE SRRUCTURE ASME B16.34 ASME B16.10
1 BC-SWING (BOLTED BONNET,SWING) API600M ASME B16.10
2 PS-PISTON-LIFT (PRESSURE SEAL BONNET,PISTON-LIFT) API600M ASME B16.10
3 WAFER TYPE (WAFER CHECK VALVE) API594 API594
4 TILTING-DISC (TILTING-DISC TYPE CHECK VALVE) API600M ASME B16.10
5 BB-BG-OS&Y-F (BOLTED BONNET,BOLTED GLAND,OS&Y,WITH SPECCIAL PACKING) API600/API600M ASME B16.10
6 BB-BG-OS&Y (BOLTED BONNET,BOLTED GLAND,OS&Y) API600/API600M ASME B16.10
7 BB-BG-OS&Y-H (BOLTED BONNET,BOLTED GLAND,OS&Y,WITH   BLOMING HOLE) API600/API600M ASME B16.10
8 PS-BG-OS&Y (PRESSURE SEAL BONNET,BOLTED GLAND,OS&Y) API600/API600M ASME B16.10
9 PS-COVER SWING (PRESSURE SEAL BONNET, SWING) API600/API600M ASME B16.10
M BB-BG-M-SEAL PRESSURE SEAL BONNET,BOLTED GLAND,moving sealing API600M ASME 16.10

connection types:

code connection type explaination
S SW SOCKET WELDED
T NPT 60° Taper pipe thread/NATIONAL TAPER PIPE THREAD
G Rc 55° TAPER PIPE THREAD
R RF RAISED FACE
J RJ RING JOINT
W BW BUTT-WELDED
P PIPE EACH ENDWITH A 150mm SHORT PIPE
F MF(F) MALE-FEMALE FACE(FEMALE)
A RF-NPT one side RF, one side NPT

Tianjin Tanghai Valve Manufacturing Co., Ltd. is one of the largest butterfly valve manufacturers in China. It was founded in 2006. Its predecessor was Tanghai Valve Manufacturing Factory. Now we have our own independent R & D, manufacturing, assembly and warehousing workshops; we have professional pre-sale and after-sale technical support and perfect services.

Our products use advanced manufacturing technology, and strictly conform to API, DIN, BS, EN, ISO, GB and other international standards. The main products are butterfly valves, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…), etc. Our products are widely used in various fields such as marine industry, shipbuilding, petrochemical, metallurgy, water treatment, fire fighting, water supply and drainage, etc. The company has won unanimous recognition and praise from customers with high quality and good reputation.

Tianjin Tanghai Valve Manufacturing Co., Ltd. is one of the largest butterfly valve 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…)

URL: http://www.tanghaivalve.com

Name: Harry Li

Email: harry@tanghaivalve.com

Wafer butterfly valve-PN20-WCB-ANSI-150 (4)

Wafer butterfly valve-PN20-WCB-ANSI-150 (4)

Wafer butterfly valve-PN20-WCB-ANSI-150 (2)

Wafer butterfly valve-PN20-WCB-ANSI-150 (2)

Wafer butterfly valve-PN20-WCB-ANSI-150 (6)

Wafer butterfly valve-PN20-WCB-ANSI-150 (6)

Wafer butterfly valve-PN20-WCB-ANSI-150 (1)

Wafer butterfly valve-PN20-WCB-ANSI-150 (1)

rising stem gate valve-OS&Y

rising stem gate valve-OS&Y

 

The difference between carbon steel and cast steel

What is the difference between cast steel and carbon steel? First, steel is classified by chemical composition
(1) Carbon steel: a. Low carbon steel (C≤0.25%) b. Medium carbon steel (C≤0.25~0.60%) c. High carbon steel (C≤0.60%)
Steel is classified according to the forming method: (1) Forged steel (2) Cast steel (3) Hot rolled steel (4) Cold drawn steel. The so-called cast steel and carbon steel are just the names produced by the different classifications of steel.

What is the difference between forged steel valve and cast steel valve? Forging and casting are two different

flanges

flanges

processing techniques.
Casting: The molten liquid metal fills the cavity and cools. Pores are easy to produce in the middle of the workpiece.
Forging: It is mainly formed by extrusion at high temperature. Can refine the crystal grain in the part.
Forging: Use hammering and other methods to make a metal material in a plastic state into a workpiece with a certain shape and size, and change its physical properties.
Casting: The metal is heated and melted and poured into a sand mold or mold, and solidified into a utensil after cooling.
The difference in performance
During forging, the metal undergoes plastic deformation to refine grains.

What is the difference between a cast iron valve and a cast steel valve? The main difference between cast iron and cast steel valves is the carbon content, which directly affects the strength and plasticity of the steel. Carbon steel is also called carbon steel, an iron-carbon alloy with a carbon content of less than 2% WC. In addition to carbon, carbon steel generally contains a small amount of silicon, manganese, sulfur, and phosphorus. According to its purpose, carbon steel can be divided into three types: carbon structural steel, carbon tool steel and free-cutting structural steel. Carbon structural steel is divided into building structural steel and machine-manufactured structural steel. According to the carbon content, carbon steel can be divided into low-carbon steel (WC ≤ 0.25%) and medium-carbon steel (WC0.25%-0.6%) And high-carbon steel (WC>0.6%) According to phosphorus and sulfur content, carbon steel can be divided into ordinary carbon steel (higher phosphorus and sulfur), high-quality carbon steel (lower phosphorus and sulfur) and high-quality Steel (lower phosphorus and sulfur) Generally, the higher the carbon content of carbon steel, the higher the hardness and the higher the strength, but the lower the plasticity.
The full name of carbon steel is carbon structural steel. Cast steel valves are also carbon steel valves (there are also cast iron valves). They are just made by casting methods, while common steels are made by rolling. The ingredients are the same.

What is the difference between cast steel, cast iron and carbon steel in valve materials? Simply put, you first

lug type butterfly valve, ductile iron, center lined,

lug type butterfly valve, ductile iron, center lined,

distinguish between iron and steel. Both steel and iron are alloys based on iron and carbon as the main additive element, collectively referred to as iron-carbon alloys.
The cast iron is smelted in an iron melting furnace to obtain cast iron (liquid), and the liquid cast iron is cast into a casting, which is called a cast iron.
What is the difference between cast steel and carbon steel. First, steel is classified by chemical composition
(1) Carbon steel: a. Low carbon steel (C≤0.25%); b. Medium carbon steel (C≤0.25~0.60%); c. High carbon steel (C≤0.60%).
Steel is classified according to the forming method: (For valves with different pressures, different materials are used.
Medium and low pressure valve, the valve body material is cast iron. For high-pressure valves, because of the large pressure, the valve body must be made of cast steel. Special valves may use various alloy materials and stainless steel.
It is said that carbon steel is only a kind of steel, and cast steel is a processing method of steel, not a concept.

What is the difference between carbon steel gate valve and cast steel gate valve. Many people think that carbon steel gate valves and cast steel gate valves are two kinds of materials.
1. The cast steel check valve and carbon steel check valve are check valves of the same material, both of which are made of WCB A216 carbon steel.
2. Cast steel check valve, because the valve body of WCB material is cast, so the name suggests, it is called cast steel check valve.
3. Carbon steel check valve, because the main material of WCB material is carbon steel, it is named carbon steel check valve.

The forging process of steel is different in processing form. Cast steel The steel used for pouring castings. A kind of casting alloy. Cast steel is divided into cast carbon steel, cast low alloy steel and cast special steel. Cast steel refers to a type of steel casting produced by casting methods. Cast steel is mainly used to manufacture some parts with complex shapes, difficult to forge or cutting and forming, but require high strength and plasticity. Forged steel: Forged steel refers to various forgings and forgings produced by forging methods. The quality of forged steel parts is higher than that of cast steel parts, can withstand large impact forces, and have plasticity, toughness and other mechanical properties.

What is the meaning of cast steel and carbon steel of the valve? What is the meaning of cast steel and carbon steel. Thank you. Carbon steel is represented by CS, but it is generally not mentioned in the case of cast steel. Detailed materials such as WCB, WCC, LCC, etc. will be stated.

The valve is a control component in the fluid conveying system. It has the functions of cut-off, regulation, diversion, prevention of reverse flow, stabilization, diversion or overflow and pressure relief. Valves used in fluid control systems, ranging from the simplest shut-off valve to the various valves used in extremely complex automatic control systems, have a wide variety and specifications.
Valves can be used to control air, water, steam, various corrosive media, mud, oil, liquid metal and radioactive media. >>Cast steel has less carbon content, good toughness, and higher pressure and temperature resistance than cast iron. Cast iron valves are not suitable for diesel, sea water and acid media. Cast iron valves are cheaper. Their materials are obviously different, and they are used in different environments! The cost is also different. In short, the price is analyzed in detail, and the properties of various materials are different. Temperature resistant. Cast steel valves can withstand high temperatures, but cast iron valves cannot be used with water.

The difference between American, Germany and China standard valve

The difference between American standard valve, German standard valve and China standard valve

lug type butterfly valve, ductile iron, center lined,

lug type butterfly valve, ductile iron, center lined,

(American Standard, German Standard, National Standard) The difference between the valves:
First of all, it can be distinguished from the standard codes of various countries: GB is the national standard, 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, globe valve, J, throttle valve, L, drain valve, P, ball valve, Q, trap, S, gate valve, and so on. ,
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 the valve is flanged, the corresponding flange standard must be adopted. The world’s main 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. ,
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 the valve designed, manufactured, produced and tested according to our country’s standard. 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.
National Standard Valves American Standard Valves German Standard Valves (American Standard, German Standard, National Standard) Valve Standards: Chinese National Standards (GB) Chinese Ministry of Machinery Standards (JB) American National Standards (ANSI) American Petroleum Institute Standards (API) American Society for Testing and Materials Standards (ASTM) American Valve and Fitting Manufacturers Standardization Association Standards (MSS) Japanese Industrial Standards (JIS) German National Standards (DIN) French National Standards (NF) British National Standards, European Standards (BS, EN) Other National Valve Standards ( ГOCT, IEEE, UL)

Tianjin Tanghai Valve Manufacturing Co., Ltd. is one of the largest butterfly valve manufacturers in China. It was founded in 2006. Its predecessor was Tanghai Valve Manufacturing Factory. Now we have our own independent R & D, manufacturing, assembly and warehousing workshops; we have professional pre-sale and after-sale technical support and perfect services.

After 14 years of continuous development and innovation, the company now has a group of high-tech engineers, technicians and skilled production workers, advanced production technology, sophisticated manufacturing equipment, complete testing methods, in strict accordance with international standards and quality management system, formed A comprehensive quality control network.

Our products use advanced manufacturing technology, and strictly conform to API, DIN, BS, EN, ISO, GB and other international standards. The main products are butterfly valves, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…), etc. Our products are widely used in various fields such as marine industry, shipbuilding, petrochemical, metallurgy, water treatment, fire fighting, water supply and drainage, etc. The company has won unanimous recognition and praise from customers with high quality and good reputation.

Main application areas of 10 major types of valves

With the development of society and various needs of modern life, spare parts for the production of these important products are also emerging in endlessly areas. Below we list the main application areas of these 10 categories of

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

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

valves.

1. Valves for petroleum installations;

1) Oil refining plant,
Most of the valves used in oil refining equipment are pipeline valves, mainly gate valves, stop valves, check valves, safety valves, ball valves, butterfly valves, and traps. Among them, gate valves account for about 80% of the total number of valves (valves account for about 80% of the total number of valves). 3% to 5% of investment);

2) Chemical fiber device,
Chemical fiber products mainly include polyester, acrylic and vinylon. Ball valves and jacketed valves (jacketed ball valves, jacketed gate valves, jacketed stop valves) of the valves they need;

3) Acrylonitrile device.
The device generally requires standard valves, mainly gate valves, globe valves, check valves, ball valves, traps,

lift-swing-check-valve-2

lift-swing-check-valve-2

needle globe valves, and plug valves. Among them, gate valves account for about 75% of the total valve;

4) Synthetic ammonia plant.
Because the ammonia source and purification method are different, the process flow is different, and the technical function of the required valve is also different. At present, domestic ammonia plants mainly need gate valves, globe valves, check valves, traps, butterfly valves, ball valves, diaphragm valves, regulating valves, needle valves, safety valves, high temperature and low temperature valves;

2, Hydropower station application valve
The construction of power stations in my country is developing towards large-scale, so large-caliber and high-pressure safety valves, pressure reducing valves, stop valves, gate valves, butterfly valves, emergency shutoff valves and flow control valves, spherical sealing instrument stop valves are required (according to the country In the “Tenth Five-Year Plan”, in addition to Inner Mongolia and Guizhou provinces, which can build units with more than 200,000 kilowatts, other provinces and cities can only build units with more than 300,000 kilowatts);

3, metallurgical application valve
The behavior of alumina in the metallurgical industry mainly requires wear-resistant slurry valves (in-flow stop valves) and regulating traps. The steelmaking industry mainly needs metal sealed ball valves, butterfly valves and oxidation ball valves, stop flash and four-way reversing valves;

13 gate-valve-5

13 gate-valve-5

4, marine application valve
With the development of offshore oilfield exploitation, the amount of valves required for its offshore production has gradually increased. Offshore platforms need to use shut-off ball valves, check valves, and multi-way valves;

5, food and medicine application valve
This industry mainly needs stainless steel ball valves, non-toxic all-plastic ball valves and butterfly valves. Among the above 10 categories of valve products, the demand for general valves is more, such as instrument valves, needle valves, needle globe valves, gate valves, globe valves, check valves, ball valves, and butterfly valves.

6, rural and urban construction application valves
The urban construction department generally uses low-pressure valves, and is currently developing in the direction of environmental protection and energy saving. Environmentally friendly rubber plate valves, balance valves, centerline butterfly valves, and metal seal butterfly valves are gradually replacing low-pressure iron gate valves. Most of the valves used in domestic urban construction are balance valves, soft-seal gate valves, butterfly valves, etc.;

7. Valves for rural and urban heating
In the urban heat generation system, a large number of metal-sealed butterfly valves, horizontal balance valves and direct-buried ball valves are needed, because these valves solve the problem of vertical and horizontal hydraulic imbalance of pipelines, and achieve the purpose of energy saving and heat balance.

8. Environmental protection valve
In the domestic environmental protection system, the water supply system mainly requires centerline butterfly valves, soft-sealed gate valves, ball valves, and exhaust valves (used to remove air in the pipeline). The sewage treatment system mainly needs soft sealing gate valve and butterfly valve;

9. Gas valve
City gas accounts for 22% of the entire natural market, with a large amount of valves and many types. Mainly need ball valve, plug valve, pressure reducing valve, safety valve;

10. Valves for pipeline applications
Long-distance pipelines are mainly crude oil, finished products and natural pipelines. The most commonly used valves for this type of pipeline are forged steel three-body full bore ball valves, anti-sulfur flat gate valves, safety valves, and check valves.

Accuracy requirements of Equipment installation

1. For static equipment
The vertical deviation of vertical equipment should not be greater than L/1000 and not greater than 10mm. Unless the drawings have special requirements.

lug type butterfly valve, ductile iron, center lined,

lug type butterfly valve, ductile iron, center lined,

The horizontal deviation of horizontal equipment should not be greater than L/1000 in the axial direction and 2D/1000 in the radial direction.

2. For moving equipment
When the pump is aligned, the selection of the installation datum and the allowable deviation of the level must meet the requirements of the “special specification” or the pump technical file. Generally, the allowable deviation of horizontal horizontality is 0.10mm/m, and the allowable deviation of vertical horizontality of the installation datum part is 0.05mm/m. The leveling and alignment values ​​must not be adjusted by loosening the anchor bolts.
1. The pump that is disassembled and installed is based on the processing surface of the pump body, and the allowable deviation of the horizontality of the pump in the vertical and horizontal directions is 0.05mm/m.
2. The integrally installed pump should be leveled based on the inlet and outlet flange surface or other horizontal processing datum plane. The allowable deviation of horizontality is 0.05mm/m in the longitudinal direction and 0.10mm/m in the transverse direction.
3. When the driving shaft and the driven shaft are connected by a coupling, the centering deviation of the two shafts and the gap between the end faces of the two shafts should be:
Centering deviation: the radial displacement is not more than 0.03mm.
The axial tilt should not be greater than 0.05/1000.
The end face gap is 1.00~3.5mm.

What is the transmission ratio

In a mechanical transmission system, the ratio of the angular velocity or rotational speed of the driving wheel at the beginning and the driven wheel at the end.
Transmission ratio (i) = ratio of driving wheel speed (n1) to driven wheel speed (n2) = inverse ratio of gear index circle diameter = ratio of driven gear teeth (Z2) to driving gear teeth (Z1).
That is: i=n1/n2=D2/D1 i=n1/n2=z2/z1
For multi-stage gear transmission
1: The transmission ratio between every two shafts is calculated according to the above formula
2: The total transmission ratio from the first axis to the nth axis is calculated according to the following formula: Total transmission ratio ι=(Z2/Z1)×(Z4/Z3)×(Z6/Z5)……=(n1/n2)× (N3/n4)×(n5/n6)……

For multi-stage gear transmission

For multi-stage gear transmission

Extended information

The ratio of the angular velocities of the two rotating components in the mechanism is also called the speed ratio. The transmission ratio of component a and component b is Ⅰ=ωa/ωb=na/nb, where ωa and ωb are the angular velocities (radians/sec) of components a and b, respectively; na and nb are the rotational speeds of components a and b respectively ( Rpm) (Note: a and b after ω and n are subscripts).
When the angular velocity in the formula is an instantaneous value, the obtained transmission ratio is the instantaneous transmission ratio. When the angular velocity in the formula is an average value, the obtained transmission ratio is the average transmission ratio. For most gear transmissions and friction wheel transmissions with the correct tooth profile, the instantaneous transmission ratio is unchanged; for chain transmission and non-circular gear transmission, the instantaneous transmission ratio is variable.
For meshing transmission, the transmission ratio can be expressed by the number of teeth Za and Zb of wheel a and wheel b, i=Zb/Za; for friction transmission, the transmission ratio can be expressed by the radius Ra and Rb of wheel a and wheel b, i=Rb/Ra, At this time, the transmission ratio generally means the average transmission ratio.
In hydraulic transmission, the transmission ratio of the hydraulic transmission element generally refers to the ratio of the turbine speed S and the pump wheel speed B, that is, =S/B. Hydraulic transmission elements can also be combined with mechanical transmission elements (generally with various gear trains) to obtain various transmission ratios of different values ​​(see gear trains for gear train transmission ratios).

Description of lining material for rubber lining valve

Overview of rubber-lined valves:
Rubber-lined valve (lined valve) is a valve suitable for pipelines containing corrosive media and high sealing requirements. Generally, the applicable temperature should not be too high, and it is not suitable for use in media

double-wing-check-valve-3

double-wing-check-valve-3

containing particles to avoid scratches. Scratches or scratches the sealing surface, causing the valve to leak. Rubber-lined valve is a kind of plastic product produced by the chemical reaction of many chemical substances. The main materials are: soft rubber, hard rubber, butyl rubber, natural rubber, EPDM rubber, fluorine rubber, Lining silicone rubber, etc., its main working purposes are: diversion, adjustment, throttling, cut-off, check, diversion, overflow, etc., which means that as long as it is a general fluid valve, it can be controlled.

The main lining materials of rubber-lined valves:
【Neoprene, Code CR】
Applicable temperature: -10℃~105℃ Animal oil, vegetable oil, inorganic lubricating oil and corrosive slurries with a wide range of pH value, good wear resistance.
【Soft Rubber Code BR】
Applicable temperature: -10℃~85℃
Applicable medium: good wear resistance. Mainly used for sulfuric acid below 50%, sodium hydroxide, potassium hydroxide, neutral salt bath solution and ammonia solution, cement, clay, cinder ash, granular fertilizer and solid fluids with strong abrasiveness, and thick viscous liquids of various concentrations Wait. _
【Butyl Rubber Code IIR】 Applicable temperature: -10℃~120℃
Applicable medium: corrosion resistance and wear resistance. Can withstand most organic acids, alkalis and hydroxide compounds, inorganic salts and inorganic acid element gases, alcohols, aldehydes, ethers, ketones, esters, etc., ≤30% sulfuric acid, phosphoric acid, hydrofluoric acid, animal oil , Vegetable oil, caustic alkali and a variety of lipids. _
【Hard Rubber Code NR】 Applicable temperature: -10℃~85℃
Applicable medium: hydrochloric acid, fluorosilicic acid, formic acid and phenolic acid, hydrochloric acid, 30% sulfuric acid, 50% hydrofluoric acid, except strong oxidants (such as organic solvents such as acid, chromic acid, concentrated sulfuric acid and hydrogen peroxide) Acid, 80% phosphoric acid, alkali, salt, metal plating solution, sodium hydroxide, potassium hydroxide, neutral salt solution, 10% sodium hypochlorite, wet chlorine, ammonia, most alcohols, organic acids and aldehydes, etc.

Working principle diagram of swing check valve

Working principle diagram of swing check valve
Swing check valve, also known as check (flow) valve, is an automatic valve used on one-way flow pipelines to prevent the medium from flowing back. It depends on the pressure of the pipeline medium to open or close the valve. It can be divided into single valve type , Double valve type and multi valve type, are one of the more commonly used valves. Swing check valves are generally suitable for pipelines with relatively clean fluid media. They are not suitable for

swing-check-valve-working-principle-diagram

swing-check-valve-working-principle-diagram

working conditions with high viscosity or solid particles. Otherwise, the check valve will be insensitive to opening and cannot achieve a complete seal. The answer is not reliable enough. The swing check valve only allows the medium to flow in one direction, which can effectively prevent the medium from flowing back to prevent accidents.

The working principle of the swing check valve:
The disc of the swing check valve and the rocker are connected together, and can rotate a certain angle around the pin shaft. When the pipeline fluid flows in the specified direction (from left to right), the inlet pressure of the disc is higher than the outlet pressure. At this time, the disc is pushed away from the valve seat and rotates around the pin to a certain position, and the valve is in the open state. When the pressure difference between the two sides of the valve flap decreases to a certain level, the valve flap falls and returns to the closed state. When the fluid flows from right to left, that is, reverse flow, the pressure on the right side of the valve disc is higher than the pressure on the left side, and the force generated by the pressure difference on both sides presses the valve disc on the valve seat, and the fluid cannot pass through, the medium Can not flow back; and the greater the fluid pressure, the tighter the sealing surface is, and the better the sealing effect. To

The installation position of the swing check valve is not restricted. It can be installed horizontally in the pipeline, or on a vertical or inclined pipeline, but if it is installed on a vertical pipeline, the flow direction of the medium should be from bottom to top.

Working principle diagram of lift check valve

Lifting check valve structure:

Lifting check valve is a kind of valve that prevents pipeline media from flowing back, mainly composed of valve body, valve seat, valve flap, valve cover and other related parts. The lift check valve is equipped with a spring to ensure that the disc is always in a dynamic equilibrium state under the action of the spring. Regardless of the medium pressure at the inlet of the valve, the valve can maintain a balanced operation.

lift check valve Working principle diagram

lift check valve Working principle diagram

The working principle of the lift check valve:

The lift check valve has a guide rod on the disc, which can move up and down freely in the guide hole of the valve cover. When the pipeline medium flows in in the specified direction (from left to right), and the pressure below the valve flap exceeds the pressure above it, push the valve flap to rise along the center line of the guide hole of the valve cover, and the valve will automatically open to allow the medium to flow; if the fluid flows from the right to the right Left flow, that is, when it flows backward, the pressure above the valve flap is greater than the pressure below it. The pressure difference between the upper and lower pressures and the weight of the valve flap press the valve flap on the valve seat, so that the medium cannot pass through, that is, the fluid cannot flow back; and pipeline fluid The greater the pressure, the tighter the sealing surface is, and the better the sealing effect.

The seat sealing surface of the lift check valve can be welded, or it can be made into a seat sealing ring and then expanded or threaded on the valve body; when the valve body is made of stainless steel, the sealing surface can also be on the valve body It is directly processed from above. The sealing surface of the disc can be directly processed on the disc, or can be processed after surfacing or welded on the disc with the inner and outer periphery of the sealing ring. The straight-through lift check valve can only be installed on the pipeline in a balanced way, and the center line of the valve flap is vertical to the horizontal plane, while the vertical lift check valve is not subject to this restriction.

What is butt welding? (8)- typical workpieces

Butt welding of typical workpieces
1, butt welding of small section workpieces

wire with diameter d≤5mm is mostly used for resistance butt welding,
Small diameter wires, wires of different materials, and wires and stamping parts (such as resistors and diode end caps) can be welded by capacitive energy storage type, which is characterized by very hard welding conditions and

resistance butt welding-Schematic diagram

resistance butt welding-Schematic diagram

extremely narrow heating range, which greatly reduces The influence of the thermal and physical properties of the welded metal on the formation of the joint.
2. Butt welding of rods
is mostly used in the butt welding of steel bars in the construction industry, usually resistance butt welding is used for diameter d<10mm; continuous flash butt welding for d>10mm; preheated flash butt welding for d>30mm. When using a manual butt welding machine, because the power of the welding machine is small (usually not more than 50KVA), when d=15-20mm, it is generally necessary to use preheated flash butt welding.

Semi-circular or V-shaped clamp electrodes can be used for butt welding of rods. The latter can be used in various diameters, so it is widely used. The rods are of solid cross-section, with greater rigidity, and longer extension lengths can be used.
3, pipe butt welding
Pipe butt welding is widely used in boiler manufacturing, pipeline engineering and petroleum equipment manufacturing. Choose continuous or preheated flash butt welding according to the section and material of the pipe. The clamp electrode can be semicircular or V-shaped. Usually when the ratio of pipe diameter to wall thickness is greater than 10, a semicircle can be selected to prevent the pipe from being crushed. V-shape can be used when the ratio is less than 10. To prevent the tube from slipping in the clamp electrode, the clamp electrode should have an appropriate working length. When the pipe diameter is 20-50mm, the length of the workpiece is 2-2.5 times the pipe diameter; when the pipe diameter is 200-300mm, it is 1-1.5 times.

Because the tube has an expanded cross-section, the heat dissipation is faster, the liquid metal on the end surface is easy to cool, and it is difficult to extrude during upsetting. The area is scattered, and the self-protection effect is weakened during the flashing process. Therefore, when the process parameters are not selected properly, non-metallic inclusions will remain in the interface to form gray spot defects. Maintain stable flash, increase flash and upsetting speed, and adopt gas protection to reduce or eliminate gray spots.

After the pipe is welded, the internal and external burrs need to be removed to ensure that the external surface of the pipe is smooth and there is a certain channel aperture inside. Deburring requires special tools.

4, thin plate butt welding

flash butt welding-schematic diagram

flash butt welding-schematic diagram

Thin plate butt welding is widely used in the continuous production line of rolled steel plate in the metallurgical industry. The width of the plate is from 300 to 1500mm or more, and the thickness is from less than 1mm to more than ten mm. The materials include carbon steel, alloy steel and non-ferrous metals and their alloys. After the plate is butt welded, the joint will undergo rolling and produce great plastic deformation, so it must not only have a certain strength, but also a high plasticity. For steel plates with a thickness of less than 5mm, continuous flash butt welding is generally used, and a plane electrode is used for single-sided conduction. When the plate is thick, preheated flash butt welding is used for double-sided conduction to ensure uniform heating along the entire end surface.

When welding thin plates, due to the relatively large cross-section length and width, the area is scattered, the joint cools quickly, and the self-protection effect is weak during the flashing process. At the same time, the liquid lintel is small and the liquid metal layer on the end surface is thin. Prone to oxidation and solidification. Therefore, the flashing and upsetting speed must be increased. After welding, the burr must be removed with a burr cutting device while it is hot.
5. Butt welding of ring parts
When welding ring parts (such as wheel rims, chain rings, bearing rings, jet engine mounting edges, etc.), in addition to considering the general rules of butt welding process, attention should be paid to the influence of shunting and ring deformation elasticity. Due to the shunt, the required power should be increased by 15-50%. Although the diameter of the ring decreases, the cross section increases, and the material resistivity decreases.

When the ring parts are butt welded, the upsetting pressure must consider the influence of the deformation rebound force, but because the shunt has the effect of heating the ring back, the increase in the upsetting pressure is not large.

Bicycles, motorcycle rims, and automobile rims all use continuous flash butt welding, and the front mouth of the clamp electrode must match the cross-section of the workpiece. During upsetting, in order to prevent the rebound force from affecting the quality of the joint, or even pull the joint apart, it is necessary to extend the time of no current upsetting.

Chain links such as anchor chains and drive chains are mostly used in the manufacture of low-carbon steel and low-alloy steel. Resistance butt welding can be used when diameter d<20mm, and preheating flash butt welding can be used when d>20mm. The purpose of preheating is to heat the interface. Uniform, easy to produce certain plastic deformation during upsetting.
6, tool butt welding
When cutting tool butt welding, one of the current process methods used to manufacture blanks in tool manufacturing is mainly the butt welding of high-speed steel (W8Cr4V, W-9Cr4V2) and medium carbon steel. Tool butt welding has the following characteristics:

1) The thermal conductivity and resistivity of high-speed steel and medium-carbon steel are quite different. At room temperature, medium carbon steel λ=0.42W/(cm℃), ρ0=18-22uΩcm; high-speed steel λ=0.23W/(cm℃), ρ0=48Ωcm. In order to make the temperature distribution on both sides of the joint surface basically the same , The extension length of high speed steel should be 30-50% smaller than that of medium carbon steel. Under normal circumstances, the extension length of high-speed steel is (0.5-1.0)d. In order to prevent excessive heat dissipation, the extension length is not less than 10mm.

2) High-speed steel has a high tendency to quench, the hardness after welding will be greatly increased, and quenching cracks may occur. In order to prevent cracks, preheating flash butt welding can be used. During preheating, heat the metal in the range of 5-10mm near the interface to 1100-1200℃. After welding, it is annealed in an electric furnace at 600-700℃ for 30 minutes.

3) When high-speed steel is heated to a high temperature, it will produce grain growth or the formation of ledeburite eutectic on the semi-melted grain boundary, making the joint brittle. The ledeburite eutectic cannot be eliminated by heat treatment. Therefore, it is necessary to use sufficient upsetting to eliminate this structure.