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Conversion of valve nominal diameter and inch | comparison table

October 12, 2020

Valve nominal diameter|valve nominal diameter
Definition of valve nominal diameter:

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

Nominal diameter (or nominal diameter), also known as average outer diameter, refers to the size of all piping accessories in the piping system. The nominal diameter is a convenient round integer for reference. The nominal diameter of the valve is marked with a number followed by the letter DN. DN represents the internal diameter of the pipe in millimeters. For example, DN50 is 50 millimeters. The American standard valve is usually expressed in inches (“), and the fractional valve is to express the internal diameter of the pipe in inches. The conversion formula is 1”=25.4mm, such as 8” is equivalent to the domestic DN200mm.

Valve nominal diameter comparison table:
The nominal diameter of the valve (NPS-NOMINAL PIPE SIZE) is not necessarily the same as the diameter of the flow channel. For the selection of its size, the required Cv value is calculated from the conditions of the conveying fluid, and then the Cv value (refer to the manufacturer’s catalog) is used to select a suitable valve The nominal diameter (NPS) is the nominal inner diameter that characterizes the valve diameter. The national standard is expressed by DN and the unit is mm. The American standard is expressed in inches. The conversion relationship between inch NPS and metric DN is as follows:

No.	inch	DN/mm	No.	inch	DN/mm	No.	inch	DN/mm
1	1/8	4	17	10	250	33	42	1050
2	1/4	8	18	12	300	34	48	1200
3	3/8	10	19	14	350	35	54	1350
4	1/2	15	20	16	400	36	60	1500
5	3/4	20	21	18	450	37	64	1600
6	1	25	22	20	500	38	72	1800
7	11/4	32	23	22	550	39	80	2000
8	11/2	40	24	24	600	40	84	2100
9	2	50	25	26	650	41	88	2200
10	21/2	65	26	28	700	42	96	2400
11	3	80	27	30	750
12	31/2	90	28	32	800
13	4	100	29	34	850
14	5	125	30	36	900
15	6	150	31	38	950
16	8	200	32	40	1000

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

Working principle diagram of lift check valve

October 9, 2020

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

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? (9)- New technology of flash butt welding

September 29, 2020

New technology of flash butt welding
1) Program-controlled reduced-voltage flash butt welding is characterized by the use of higher secondary no-load voltage at the beginning of the flash to facilitate the initiation of the flash. When the end surface temperature rises, the low-voltage flash is used and maintained The flash speed remains unchanged to improve thermal efficiency.

flash butt welding-schematic diagram

When approaching the upsetting, increase the secondary voltage to make the flash stronger to increase the self-protection effect.
Program-controlled reduced-voltage flash butt welding is compared with preheated flash butt welding. It has the advantages of short welding time, low power required, and uniform heating.

2) Pulse flash butt welding. The characteristic of this welding method is that in the stroke of the moving clamp, a reciprocating vibration stroke is superimposed through the hydraulic vibration device, the amplitude is 0.25-1.2mm, and the frequency is 3-35Hz. Tune. Due to the vibration, the end face of the weldment is alternately short-circuited and pulled apart, resulting in a pulse flash.

Compared with ordinary flash butt welding, pulse flash butt welding has no spontaneous blasting of the lintel, the splashed particles are small and the flame is shallow, so the thermal efficiency can be more than doubled, and the upsetting allowance can be reduced to 2/3-1/ 2.

The above two methods are mainly to meet the needs of flash butt welding of large section workpieces.

3) Rectangular wave flash butt welding Compared with power frequency AC sine wave flash butt welding, this welding method can significantly improve the stability of the flash. Because the sine wave power supply will instantly interrupt the flash when the voltage is close to zero, and the rectangular wave can evenly produce the flash in the full cycle. It has nothing to do with the voltage phase.

The number of flashes per unit time of the rectangular wave power supply is 30% higher than that of power frequency AC, the sprayed metal particles are fine, the flame is shallow and the thermal efficiency is high. The rectangular wave frequency can be adjusted within the range of 30-180Hz. This method is mostly used for continuous flash butt welding of thin plates and aluminum alloy wheels.

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

What is butt welding? (8)- typical workpieces

September 29, 2020

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

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

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.

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

What is butt welding? (7)- Flash butt welding of common metals

September 29, 2020

The following describes the characteristics of flash butt welding of several commonly used metal materials:

1. Flash butt welding of carbon steel

This kind of material has the advantages of high resistivity, the oxidation of carbon element during heating provides a protective atmosphere for the interface CO and CO2, and does not contain elements that generate high melting point oxides. Therefore, they are all materials with better weldability.

flash butt welding-schematic diagram

As the carbon content in steel increases, the resistivity increases, the crystallization interval, the high temperature strength and the hardening tendency increase. Therefore, it is necessary to increase the upsetting pressure and the upsetting allowance accordingly. In order to reduce the effect of quenching. Preheating flash butt welding can be used, and post-weld heat treatment can be performed.

During flash butt welding of carbon steel, because carbon diffuses to the heated end surface and is strongly oxidized, and during upsetting, the molten metal with high carbon content in the semi-melting zone is squeezed out, so a low carbon content is formed at the joint. Carbon layer (white, also called bright band). The width of the carbon-depleted layer increases as the steel content increases and the preheating time increases; as the carbon content increases and the gas medium oxidation tendency decreases, it becomes narrower. Long-term heat treatment can eliminate the carbon-poor layer.

The most frequently used is carbon steel flash butt welding. As long as the welding conditions are selected appropriately, there will generally be no difficulties. The same is true even for cast iron, which is difficult to weld for melting.

Cast iron usually uses preheated flash butt welding, and continuous flash butt welding is easy to form a white hole. Due to the high carbon content, a large amount of CO and CO2 protective atmosphere is generated during flashing, and the self-protection effect is strong. Even when the process parameters fluctuate greatly, there are only a small amount of oxidized inclusions in the interface.

2, flash butt welding of alloy steel

The influence of alloying element content on steel properties and the process measures to be taken are as follows:

1) Aluminum, chromium, silicon, molybdenum and other elements in steel are prone to produce high melting point oxides. The flash and upsetting speed should be increased to reduce their oxidation.

2) As the content of alloying elements increases, the high temperature strength increases, and the upsetting pressure should be increased.

3) For pearlitic steel, the increase in alloying elements increases the tendency to quench, and measures should be taken to prevent quenching embrittlement.

The welding characteristics of low alloy steel are similar to that of medium carbon steel, and have a tendency to harden, so the corresponding heat treatment method should be adopted. This type of steel has high high-temperature strength and is easy to generate oxide inclusions. It requires higher upsetting pressure, higher flashing and upsetting speed.

In addition to the characteristics of high-carbon steel, high-carbon alloy steel also contains a certain amount of alloying elements. Due to the high carbon content and wide crystallization temperature range, the semi-melting zone at the interface is wider. If the upsetting pressure is insufficient and the plastic deformation is insufficient, the liquid metal remaining in the semi-melting zone will form a loose structure. It also contains high melting point oxide inclusions due to alloying elements. Therefore, higher flashing and upsetting speed, larger upsetting pressure and upsetting allowance are required.

The main alloying elements of austenitic steel are Cr and Ni. This kind of steel has high high-temperature strength, poor electrical and thermal conductivity, low melting point (compared to low carbon steel), and a large number of alloying elements that easily form high melting point oxides ( Such as Cr). Therefore, a large upsetting pressure, high flashing and upsetting speed are required. The high flashing speed can reduce the heating zone, which can effectively prevent the rapid growth of grains in the heat-affected zone and the reduction of corrosion resistance.

3, flash butt welding of aluminum and its alloys

This type of material has the characteristics of good electrical and thermal conductivity, low melting point, easy oxidation, high oxide melting point, and narrow plastic temperature zone, which bring difficulties to welding.

Aluminum alloy butt welding has poor weldability, and improper selection of process parameters can easily produce defects such as oxide inclusions and looseness, which will sharply reduce the strength and plasticity of the joint. In flash butt welding, high flash and upsetting speed, large upsetting allowance and forced upsetting mode must be used. The specific power required is much larger than that of steel parts.

4. Flash butt welding of copper and its alloys

Copper has better thermal conductivity than aluminum and has a higher melting point, so it is more difficult to solder than aluminum. In pure copper flash butt welding, it is difficult to form a liquid metal layer on the end surface and maintain a stable flash process, and it is also difficult to obtain a good plastic temperature zone. For this reason, high final flash speed, upsetting speed and upsetting pressure are required during welding.

Copper alloys (such as brass, bronze) are easier to butt welding than pure copper. During brass butt welding, the performance of the joint is reduced due to the evaporation of zinc. In order to reduce the evaporation of zinc, a high final flash speed, upsetting speed and upsetting pressure should also be used.

Aluminum and copper flash butt welding transition joints are widely used in the motor industry. Because their melting points are very different, aluminum melts 4-5 times faster than copper, so the extension length of aluminum should be increased accordingly. The process parameters of aluminum and copper flash butt welding can refer to the following table. When aluminum and copper are butt welded, the intermetallic compound CuAL2 may be formed, which increases the brittleness of the joint. Therefore, it is necessary to squeeze out CuAL2 from the interface as much as possible during upsetting.

5. Flash butt welding of titanium and its alloys

The main problem of flash butt welding of titanium and its alloys is the reduction of joint plasticity due to quenching and gas absorption (hydrogen, oxygen, helium, etc.). The quenching tendency of titanium alloys is related to the added alloying elements. If the stable β-phase element is added, the quenching tendency will increase and the plasticity will be further reduced. If continuous flash butt welding with strong flash is used, a satisfactory joint can be obtained without adding shielding gas. When using flash and preheated flash welding with a low upsetting speed, the welding should be performed in an Ar or He protective atmosphere. The preheating temperature is 1000-1200 degrees, and the process parameters are basically the same as when welding steel, but the amount of flash reserved is slightly increased. At this time, a higher plastic joint can be obtained.

What is butt welding? (5)- flash butt welding

September 29, 2020

(4) Flash speed vf A sufficiently large flash speed can ensure the strong and stable flash. However, if vf is too large, the heating zone will be too narrow, which will increase the difficulty of plastic deformation. At the same time, due to the increase in welding current required, it will increase the depth of the fire hole after the lintel blasting, which will reduce the joint quality. The following factors should also be considered when choosing vf:

flash butt welding-schematic diagram

1) The composition and performance of the material being welded. For materials with a lot of easily oxidizable elements or good electrical and thermal conductivity, vf should be larger. For example, it is larger when welding austenitic stainless steel and aluminum alloy than when welding low carbon steel;

2) Whether there is preheating. When there is preheating, it is easy to excite the flash, so vf can be improved.

3) There should be a strong flash before upsetting. vf should be large to ensure a uniform metal layer on the end face.

(5) Upsetting flow rate δu δu affects the removal of liquid metal and the magnitude of plastic deformation. If δu is too small, liquid metal will remain in the interface, which will easily form defects such as looseness, shrinkage, cracks, etc.; when δu is too large, the crystal lines will bend severely and reduce the impact toughness of the joint. δu is selected according to the cross-sectional area of the workpiece and increases with the increase of the cross-sectional area.

During upsetting, in order to prevent the interface from oxidizing, the current should not be cut off immediately before the end face interface is closed. Therefore, the upsetting flow should include two parts-current upsetting allowance and non-current upsetting allowance. The former is the latter. 0.5-1 times.

(6) Upsetting speed vu In order to avoid the difficulty of liquid metal removal and plastic metal deformation due to metal cooling in the interface area, and to prevent the end surface metal from oxidizing, the faster the upsetting speed, the better. The minimum upsetting speed depends on the properties of the metal. The minimum upsetting speed for welding austenitic steel is twice that of welding pearlitic steel. The welding of metals with good thermal conductivity (such as aluminum alloy) requires a high upsetting speed (150-200mm/s). For the same metal, if the temperature gradient in the interface area is large, the upsetting speed needs to be increased due to the fast cooling rate of the joint.

(7) The upsetting pressure Fu Fu is usually expressed by the pressure per unit area, that is, the upsetting pressure. The size of the upsetting pressure should ensure that the liquid metal in the joint can be extruded and a certain degree of plastic deformation will be produced at the joint. If the upsetting pressure is too small, the deformation will be insufficient and the strength of the joint will decrease; if the upsetting pressure is too high, the deformation will be too large, the crystal lines will bend seriously, and the impact toughness of the joint will be reduced.

The size of the upsetting pressure depends on the metal properties, temperature distribution characteristics, upsetting allowance and speed, and the shape of the workpiece section. High-temperature and strong metals require large upsetting pressure. Increasing the temperature gradient will increase the upsetting pressure. Because the high flash speed will increase the temperature gradient, when welding metals with good thermal conductivity (copper, aluminum alloy), a large upsetting pressure (150-400Mpa) is required.

(8) Preheating flash butt welding parameters In addition to the above process parameters, preheating temperature and preheating time should also be considered.

The preheating temperature is selected according to the cross-section of the workpiece and the material properties. When welding low carbon steel, it generally does not exceed 700-900 degrees. As the cross-sectional area of the workpiece increases, the preheating temperature should be increased accordingly.

The preheating time is related to the power of the welding machine, the size of the workpiece section and the performance of the metal, and it can be changed in a relatively large range. The preheating time depends on the required preheating temperature.

In the preheating process, the amount of shortening caused by preheating is very small, and it is not specified as a process parameter.

(9) The clamping force Fc of the clamp must ensure that the workpiece does not slip during the upsetting. Fc is related to the upsetting pressure Fu and the friction coefficient f between the workpiece and the clamp. Their relationship is: Fc≥Fu/2f. Usually F0=(1.5-4.0) Fu, the lower limit is taken for low carbon steel with compact section, and the upper limit is taken for cold-rolled stainless steel plate. When the clamp is equipped with a top support device, the tightening force can be greatly reduced, and Fc=0.5Fu is sufficient at this time.

3. Workpiece preparation

The preparation of the workpiece for flash butt welding includes: the geometry of the end face, the processing of the blank end and the surface cleaning.

When flash butt welding, the geometry and size of the butt surface of the two workpieces should be basically the same. Otherwise, the heating and plastic deformation of the two workpieces will not be guaranteed to be consistent, which will affect the quality of the joint. In production, the difference in diameter of round workpieces should not exceed 15%, and the difference between square workpieces and tubular workpieces should not exceed 10%.

When flashing butt welding large-section workpieces, it is best to chamfer the end of a workpiece to increase the current density to facilitate the laser flash. In this way, the secondary voltage can be increased without preheating or initial flashing.

The butt welding blank end can be processed on a shear, punch, lathe, or plasma or gas flame cutting, and then the end face can be removed.

During flash butt welding, the end metal is burned out during flash, so the end face cleaning is not very strict. However, the cleaning requirements for the contact surface between the clamp and the workpiece should be the same as for resistance butt welding.

Valve model establishment and meaning

September 27, 2020

The latest valve model compilation method
Nowadays, there are more and more types of valves and materials, and the compilation of valve models is becoming

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

more and more complicated. The standardization of valve models provides convenience for valve design and selection. Although my country has a unified standard for valve model compilation, it is gradually unable to meet the needs of the development of the valve industry. At present, valve manufacturers generally adopt a unified numbering method; if a unified numbering method cannot be used, each manufacturer can work out a numbering method according to its own situation.
The valve model compilation method specifies the valve model description, valve type, drive mode, connection form, structure form, sealing surface material, pressure and the expression method of the valve body material code. The valve model preparation method is suitable for all kinds of pipeline valves such as gate valves, globe valves, throttle valves, butterfly valves, ball valves, diaphragm valves, plug valves, check valves, drain valves, plunger valves, pressure reducing valves, traps, and safety valves. product. Standard valve model representation method The valve model compilation method should usually indicate the valve type, drive mode, connection form, structural characteristics, nominal pressure, sealing surface material, valve body material and other elements.
Unit One , valve type (code name):

butterfly valve	safety valve	Diaph-ragm valve	ball valve	gate valve	check valve	plug valve	Pressure reducing valve	globe valve	filter	Disch-arge valve
D	A	G	Q	Z	H	X	Y	J	GL	FL

Unit two, valve drive mode (code name):

drive mode	Electro-magne-tism	Electro-magnetic hydraulic	Electro-hydraulic	tur-bine	Spur gear	Bevel gear	pneu-matic	Hydr-aulic	Gas-hydr-aulic	elec-tric	han-dle	Hand-wheel
code	0	1	2	3	4	5	6	7	8	9

Unit three, valve connection method (code name):

connection	internal thread	external thread	two different connections	flange	welding	wafer	clamp	ferrule
code	1	2	3	4	6	7	8	9

Unit Four, valve structure (code name):

Butterfly valve structure (code name):

butterfly structure		butterfly code	butterfly structure		butterfly code
sealed	singl eccentric	0	unsealed	single eccentric	5
	center vertical plate	1		center vertical plate	6
	double eccentric	2		double eccentric	7
	triple eccentric	3		triple eccentric	8
	linkage mechanism	4		linkage mechanism	9

Gate valve structure (code name):

gate valve structure types				gate valve code
valve stem lift type	Wedge gate plate	Flexible gate plate		0
		rigid gate plate	single gate	1
			double gates	2
	Parallel gate plate		single gate	3
			double gates	4
non-lifting valve stem	Wedge gate plate		single gate	5
			double gates	6
	Parallel gate plate		single gate	7
			double gates	8

Ball valve structure (code name):

ball valve structure		code	ball valve structure		code
floating ball	Straight flow channel	1	fixed ball	Straight flow channel	7
	Y type three-way channel	2		four-way channel	6
	L type three-way channel	4		T type three-way channel	8
	Y type three-way channel	5		L type three-way channel	9
				Hemisphere through	0

Check valve structure (code name):

check valve structure		code	check valve structure		code
lifting disc	straight flow channel	1	swing disc	single disc	4
	vertical structure	2		multiple discs	5
	angle channel	3		double disc	6
			butterfly type check valve		7

The structure of stop valve, throttle valve and plunger valve (code name):

globe valve structure		code	globe valve structure		code
disc type unbalanced	straight flow channel	1	disc type balanced	straight flow channel	6
	Z channel	2		angle channel	7
	three-way channel	3
	angle channel	4
	DC runner	5

Diaphragm valve structure (code name):

diaphragm valve structure	code	diaphragm valve structure	code
Roof circulation	1	straight flow channel	6
DC runner	5	Y type angle channel	8

Plug valve structure (code name):

plug valve structure			plug valve structure
packing seal	straight flow channel	3	oil seal	straight flow channel	7
	T type three-way channel	4		T type three-way channel	8
	four-way channel	5

Safety valve structure (code name):

safety valve structure		code	safety valve structure		code
Spring loaded spring seal structure	full open type with heat sink	0	spring loaded,spring not close, with wrench	micro-open, double valve	3
	micro-open	1		micro-open	7
	full open	2		full open	8
	full open with wrench	4
leverage	single leverage	2	with actuator full open		6
leverage	double leverage	4	pulse		9

Structure of pressure reducing valve (code name):

pressure reducing valve structure	code	pressure reducing valve structure	code
film type	1	bellows type	4
spring film type	2	leverage type	5
piston type	3

The structure of the trap (code name):

trap	trap code	trap	trap code
float ball type	1	steam pressure type or bellows	6
float bucket	3	bimetallic	7
liquid or solid expansion type	4	pulse	8
bell float	5	disc thermaldynamic	9

The structure of the blowdown valve (code name):

blowdown valve structure		code	blowdown valve structure		code
liquid level connection discharge	cut-off straight through	1	Discontinuous discharge	Cut-off type DC	5
	cut-off angle	2		Cut-off straight-through	6
				Cut-off angle	7
				Floating gate type straight-through	8

Unit five, valve sealing material (code name):

material	Babbitt alloy	enamel	Nitrided steel	18-8series stainless steel	Fluoroplastic	hard alloy
code	B	C	D	E	F	Y
material	nylon plastic	monel	lead lining	Mo2Ti stainless steel	plastic	monel alloy
code	N	P	Q	R	S	M
material	glass	copper alloy	Cr13 stainless steel	rubber	lining	valve material machined directly
code	G	T	H	X	J	W

Unit six, valve nominal pressure (code name): The valve nominal pressure value is directly expressed with Arabic numerals, which is 10 times of MPa. The pressure of 1.0MPA is DN=1.0MPA and the nominal pressure is 10kg. Indicates the nominal pressure of the valve!
Unit seven, valve body material (code name):

valve body material	Titanium and titanium alloys	carbon steel	Cr13 series stainless steel	Chrome-molybdenum steel	malleable cast iron	aluminum alloy
code	A	C	H	I	K	L
valve body material	ductile cast iron	Mo2Ti series stainless steel	plastic	copper and copper alloy	18-8series stainless steel	grey cast iron
code	Q	R	S	T	P	Z

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

Types of valve accessories

September 25, 2020

Types of valve accessories: The valve itself is composed of a valve body and various operating mechanisms, which also contain many parts and accessories, including manual, pneumatic, electric and so on. The components assembled in different ways of use are also different.
Valve accessories mainly include:
1. Pneumatic actuator: It is mainly divided into single-acting and double-acting. Single-acting is a spring-return

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

structure, and double-acting is the principle of air opening and closing. Generally, double-acting pneumatic actuators are used for adjustment types. 2. Electric actuators: the common ones are linear, angular, compact and explosion-proof. The structure of the electric actuator is relatively complex and the cost is high, but its performance is stable, open and close quickly, and it is suitable for remote control systems.
3. Hydraulic actuator: A hydraulic actuator is a device that converts hydraulic energy into mechanical energy. There are mainly linear and rotary types. The cost is relatively high and the structure is relatively complex. It is a product with special working conditions and high requirements, and the market generalization rate is low.
4. Gas-liquid linkage actuator: The gas-liquid linkage actuator uses pipeline natural gas or nitrogen as power and hydraulic oil as the transmission medium to drive the opening and closing of pipeline valves. It is mainly used as a multifunctional driving device in natural gas, liquefied gas, nitrogen, gas liquid tank, gas, etc.
5. Electro-hydraulic linkage actuator: The electro-hydraulic linkage actuator is composed of a control module and a power module. The intelligent controllable motor accepts the function commands of the control module, controls the power module, and outputs the large distance in line or angular displacement, pneumatic control The object, at the same time, completes the adjustment process through its own displacement feedback, and realizes various functional controls.
6. Manual actuator: The manual actuator is to perfect the manual control when the current is unstable and the air pressure is insufficient. When the air pressure and current cannot be controlled under special circumstances or there is no current and air pressure for installation and maintenance, the manual feedback device can be turned on, which can be carried out quickly Manual control.

Valve components:
Handle, handwheel, worm gear, valve body, valve core, valve stem, valve cover, valve silencer, blank, bolt and nut, clamp, spring, diaphragm, packing, packing, O-ring, PTFE products Gaskets, flanges, non-standard solid parts, etc.
Positioner and accessories:
Pneumatic valve positioner, electric valve positioner, intelligent valve positioner, electro-hydraulic server, servo amplifier, electric converter, filter pressure reducing valve, valve position transmitter, position valve, solenoid valve, limit switch, pneumatic Amplifier, smart module, electro-hydraulic server, servo amplifier, alarm, explosion-proof coil, quick exhaust valve
Other valve accessories:
Valve testing machine Handle Handwheel Worm gear valve Body Valve core Valve cover Valve silencer Signal generator Rough mold bolts and nuts Clamps Springs Diaphragm Packing O-rings Flow juice Polytetrafluoroethylene products Gaskets Flanges Fast elbows Joint expander Flow meter Filter non-standard solid parts

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

Types and working principles of electric valves

September 18, 2020

The so-called electric valve, as its name implies, is to drive the opening and closing of the valve through the power

U type flange butterfly valve (6)

supply. It is mainly composed of two parts. The upper part is an electric actuator and the lower part is a valve. In industrial processes, it is used to control the travel and flow of various fluids, such as water, oil, chemical liquids, etc., based on parameters such as temperature, pressure and flow. Electric valve is a kind of self-control valve that has been widely used in recent years. With its stable reliability and multiple control functions, it can meet the requirements of most common valves that cannot be used. It has become an indispensable control device in the process pipeline.
Electric ball valve; Electric regulating valve; Electric butterfly valve;
The electric valve has a simple structure and a long service life. It is suitable for almost all media and can greatly reduce the labor intensity of the operator. It is suitable for equipment where it cannot be manually operated or is difficult to approach. It can complete remote operation of the valve, and the height of the equipment is not restricted.
Types and classifications of electric valves:

electric stainless steel gate valve

1. According to different actuators, electric valves are generally divided into two categories, one is angular stroke, the other is linear stroke, angular stroke electric valve controls 90 degree rotation to achieve the on and off of the valve, and linear stroke realizes the valve plate. The up and down actions are usually used in conjunction with equipment with a higher degree of automation.

2. According to the function, it can be divided into switch type and regulation type, intelligent type and explosion-proof type; the switch type is fully open and fully closed, and the regulation type can control any opening degree to achieve the function of adjusting the flow rate!

3. According to the valve position, it can be divided into common electric ball valves, electric butterfly valves, electric regulating valves, solenoid valves, electric gate valves, electric shut-off valves, etc., which can be applied to various occasions.

4. According to the shape of the valve body, it can be divided into ordinary electric valve and micro electric valve. The working principle of the electric valve: The electric valve is connected by the electric actuator and the valve. After installation and debugging, the valve is driven by the power supply to realize the opening and closing action of the valve, so as to achieve the purpose of switching or adjusting the pipeline medium. The opening degree of the electric valve can be controlled, and the state is open, closed, half-open and half-closed, which can control the flow of the medium in the pipeline, but the solenoid valve cannot meet this requirement.

Solenoid valve is a type of electric valve, which uses the magnetic field generated by the solenoid coil to pull the valve core, thereby changing the on and off of the valve body, the coil is de-energized, and the valve core retreats by the pressure of the spring.

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

Valve selection basis and selection guide

September 18, 2020

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

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

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

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

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

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.

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