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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? (4)- flash butt welding

September 29, 2020

2. Resistance and heating of flash butt welding

The contact resistance Rc during flash butt welding is the total resistance of the liquid metal lintel between the end faces of the two workpieces, and its size depends on the number of lintels and their cross-sectional area at the same time. The latter two are related to the cross-sectional area of the workpiece, the current density and the

flash butt welding-schematic diagram

approach speed of the two workpieces. With the increase of these three, the number of lintels and their cross-sectional area simultaneously existing increases, and Rc will decrease.

The Rc of flash butt welding is much larger than that of resistance butt welding, and it exists throughout the flashing stage. Although its resistance value gradually decreases, it is always greater than the internal resistance of the workpiece. Rc does not disappear completely until the upsetting starts. Figure 14-5 shows the general law of Rc, 2Rω and R changes during flash butt welding. The gradual decrease in Rc is due to the increase in the approach speed of the workpiece as the end surface temperature increases during the flashing process, and the number and size of the lintels increase accordingly.

Because Rc is large and there is the entire flashing stage, the heating of the joint during flash butt welding mainly depends on Rc.

Three, flash butt welding welding cycle, process parameters and workpiece preparation

1, welding cycle

The welding cycle of flash butt welding is shown in 14-7, and the reset time in the figure refers to the time from loosening the workpiece to returning to the original position. There are two preheating methods: resistance preheating and flashing preheating. The figure (b) uses resistance preheating.

2, process parameters

The main parameters of flash butt welding are: extension length, flash current, flash flow, flash speed, upsetting flow, upsetting speed, upsetting pressure, upsetting current, clamping force, etc. Figure 14-8 is a schematic diagram of each flow rate and extension length of continuous flash butt welding. The following describes the influence of various process parameters on welding quality and the principles of selection:

(1) Elongation length l0 is the same as resistance butt welding, l0 affects the temperature distribution along the axial direction of the workpiece and the plastic deformation of the joint. In addition, with the increase of l0, the impedance of the welding circuit increases, and the required power also increases. Under normal circumstances, bar and thick arm tube l0=(0.7-1.0)d, d is the diameter of the round bar or the side length of the square bar.

For thin plates (δ=1-4mm), in order not to lose stability during upsetting, generally l0=(4-5)δ.

When different metals are butt welded, in order to make the temperature distribution on the two workpieces consistent, usually the metal with poor electrical and thermal conductivity should be smaller. Table 1 is the l0 reference value for flash butt welding of different metals.

(2) The flash current If and the upsetting current Iu If depend on the cross-sectional area of the workpiece and the current density jf required for the flash. The size of jf is related to the physical properties of the welded metal, flashing speed, the area and shape of the workpiece section, and the heating state of the end surface. In the flashing process, as vf gradually increases and contact resistance Rc gradually decreases, jf will increase. During the upsetting, Rc disappears quickly, and the current will increase sharply to the upsetting current Iu. When welding large-section steel parts, in order to increase the heating depth of the workpiece, a smaller flash speed should be used, and the average jf used generally does not exceed 5A/mm2. Table 2 shows the reference values of jf and ju for flash butt welding of workpieces with a cross-sectional area of 200-1000mm2.

The magnitude of the current depends on the no-load voltage U20 of the welding transformer. Therefore, in actual production, the secondary no-load voltage is generally given. When selecting U20, in addition to considering the impedance of the welder circuit, when the impedance is large, U20 should be increased accordingly. When welding large-section workpieces, the method of adjusting the secondary voltage in stages is sometimes used. At the beginning, a higher U20 is used to excite the flash, and then it is reduced to an adaptive value.

(3) Flash flow rate δf The flash flow rate should be selected so that there is a molten metal layer on the end of the workpiece at the end of the flash, and the plastic deformation temperature is reached at a certain depth. If δf is too small, the above requirements cannot be met, which will affect the welding quality. If δf is too large, it will waste metal materials and reduce productivity. When choosing δf, you should also consider whether there is preheating, because the δf of preheating flash butt welding can be 30-50% smaller than continuous flash butt welding.

What is butt welding? (3)- flash butt welding

September 29, 2020

Flash butt welding

Flash butt welding can be divided into continuous flash butt welding and preheated flash butt welding. Continuous flash butt welding consists of two main stages: the flash stage and the upsetting stage. Preheating flash butt welding only adds a preheating stage before the flashing stage.

flash butt welding-schematic diagram

One, two stages of flash butt welding

1, flash stage

The main function of flash is to heat the workpiece. In this stage, the power is turned on first, and the end faces of the two workpieces are slightly contacted, forming many contact points. When the current passes, the contact points melt and become liquid metal lintels connecting the two ends. Due to the extremely high current density in the liquid lintel, the liquid metal in the lintel evaporates and the lintel blasts. With the slow advancement of the movable clamp, the lintels are also continuously produced and blasted. Under the action of vapor pressure and electromagnetic force, liquid metal particles are continuously ejected from the interface. The formation of a rapid stream of sparks-flash.

In the flashing process, the workpiece gradually shortens and the temperature of the tip gradually rises. As the end temperature increases, the blasting speed of the lintel will increase, and the advancing speed of the movable clamp must be gradually increased. Before the flashing process ends, a layer of liquid metal must be formed on the entire end surface of the workpiece, and the metal must reach the plastic deformation temperature at a certain depth.

Due to the strong oxidation of metal vapor and metal particles generated during lintel blasting, the oxygen content of the gas medium in the interface gap is reduced, and its oxidation capacity can be reduced, thereby improving the quality of the joint. But the flash must be stable and strong. The so-called stability means that no open circuit or short circuit occurs during the flashing process. The open circuit will weaken the self-protection effect of the weld, and the joint will be easily oxidized. A short circuit will overburn the workpiece and cause the workpiece to be scrapped. The so-called strong means that there are quite a lot of lintel blasts per unit time. The stronger the flash, the better the self-protection of the weld, which is especially important in the later flash.

2, upsetting stage

At the end of the flashing stage, immediately apply sufficient top pressure to the workpiece, and the interface gap is rapidly reduced, and the lintel stops blasting, that is, the upsetting stage is entered. The function of upsetting is to seal the gap between the end face of the workpiece and the fire hole left by the liquid metal lintel after blasting, while extruding the liquid metal and oxide inclusions on the end face, so that the clean plastic metal is in close contact, and the joint area produces a certain degree of plasticity Deformation to promote the progress of recrystallization, form common crystal grains, and obtain a strong joint. Although there is molten metal during the heating process in flash butt welding, it is actually welding in a plastic state.

Preheating flash butt welding is to heat the workpiece with intermittent current pulses before the flash phase, and then enter the flash and upsetting phase. The purpose of preheating is as follows:

(1) Reduce the required power to weld workpieces with larger cross-sectional area on a small capacity welder, because when the capacity of the welder is insufficient, it is impossible to stimulate continuous flashing without preheating the workpiece to a certain temperature. process. At this time, preheating is a last resort.

(2) Reduce the cooling rate after welding. This will help prevent the quenched structure and cracks of the quenched steel joint during cooling.

(3) Shortening the flash time can reduce the flash margin and save precious metals.

The shortcomings of preheating are:

(1) Extend the welding cycle and reduce the productivity;

(2) Make the process automation more complicated;

(3) Preheating control is difficult. If the preheating degree is inconsistent, the stability of the joint quality will be reduced.

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

Classification and characteristics of welding

September 29, 2020

Metal welding can be divided into three categories: fusion welding, pressure welding and brazing according to the characteristics of the process. The characteristics are:
1. Fusion welding: heat the workpiece to be joined to partially melt it to form a molten pool. The molten pool will be joined after cooling and solidification. If necessary, a filler can be added to assist. It is suitable for welding of various

welding

metals and alloys without pressure. .
2. Pressure welding: The welding process must apply pressure to the weldment, which belongs to the processing of various metal materials and some metal materials.
3. Brazing: Use metal materials with a lower melting point than the base material as the brazing filler metal, and use the liquid brazing filler metal to wet the base material, fill the joint gap, and mutually diffuse with the base metal to realize the connection of the weldment. Suitable for welding of various materials, and also suitable for welding of different metals or dissimilar materials.

Welding equipment can be divided into manual welding equipment and automatic welding equipment according to the degree of welding automation.
During the welding process, if the atmosphere is in direct contact with the high-temperature molten pool, the oxygen in the atmosphere will oxidize metals and various alloying elements. Nitrogen and water vapor in the atmosphere enter the molten pool, and will also form pores, slag inclusions, cracks and other defects in the weld during the subsequent cooling process, which will deteriorate the quality and performance of the weld.
There are many energy sources for modern welding, including gas flame, electric arc, laser, electron beam, friction and ultrasonic. In addition to being used in factories, welding can also be carried out in a variety of environments, such as the field, underwater and space.

No matter where it is, welding may bring danger to the operator, so appropriate protective measures must be taken when welding. The possible harm caused by welding to the human body includes burns, electric shocks, visual impairment, inhalation of toxic gases, and excessive ultraviolet radiation.
In order to improve the welding quality, various protection methods have been developed. For example, gas shielded arc welding is to isolate the atmosphere with argon, carbon dioxide and other gases to protect the arc and molten pool rate during welding.

For example, when welding steel, adding ferro-titanium powder with high oxygen affinity to the electrode coating for deoxidation can protect the beneficial elements such as manganese and silicon in the electrode from oxidation and enter the molten pool. After cooling, high-quality welds can be obtained.

The common feature of various pressure welding methods is to apply pressure during the welding process without adding filler materials. Most pressure welding methods, such as diffusion welding, high frequency welding, cold pressure welding, etc., do not have a melting process, so there is no problem like fusion welding, which has beneficial alloying elements burning and harmful elements intruding into the weld, thus simplifying the welding process. It also improves welding safety and health conditions.

At the same time, because the heating temperature is lower than that of fusion welding and the heating time is shorter, the heat affected zone is small. Many materials that are difficult to weld by fusion welding can often be welded by pressure welding to form a high-quality joint with the same strength as the base metal.

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 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

Working principle diagram of three-way valve

September 25, 2020

What is a three-way valve? Simply put, a three-way valve has three inlets and outlets; when the three-way merges, there are two in and one out, and the three-way split is one in and two out. It is controlled according to the shape of the spool. The most obvious difference in appearance between a three-way valve and a two-way valve is one more flow passage. The three-way valve is mainly used to change the flow direction of the medium. In addition to the inlet A, the outlet B, and the reversing port C, ordinary valves do not have the function of changing the flow direction of the medium.

T, L type port valve

Three-way valve structure: Three-way valves are generally divided into L-type and T-type. The T-shape can connect three orthogonal pipelines with each other and cut off the third channel, which can split and merge. The L shape can only connect two orthogonal pipes, and cannot maintain the third pipe to communicate with each other at the same time. It only plays a role of distribution.
Principle of three-way valve:
When the valve opens, the medium enters the valve from A, and flows out of the valve through B. When the bypass requires medium to flow in, the actuator is opened, the valve core is reversed, and medium A enters C out. When the pipeline does not require medium to flow in, the actuator is opened and the valve close Cut off the media.
Three-way solenoid valve:
There are several working positions of the spool. The solenoid valve is called several solenoid valves: the interface on the valve body, which is the number of passages of the solenoid valve, has several passage ports, and the solenoid valve is called a few-way solenoid valve, which means two Position means that there are two working positions that can be switched, and the three-way has three channels for ventilation.
Two-position, two-way, two-position, three-way solenoid valve principle The solenoid valve is one in and one out (two channels); one channel is connected to the air source, and the other channel is connected to the air inlet of the actuator;

Three-way solenoid valve

The two-position three-way solenoid valve controls the gas to be one inlet, one outlet and one exhaust (there are two working positions); one channel is connected to the air source, the other two channels are connected to the air inlet of the actuator, and one Adjacent to the exhaust port of the actuator;
The two-position five-way solenoid valve controls the gas to be one inlet, two outlets and one exhaust (the working position is also two); 1 air inlet (connected to the air source), 1 positive action vent hole and 1 * as a vent hole (Separately provide the target equipment with one positive and one* air source), 1 positive action exhaust hole and 1 *exhaust hole (installation*);
The three-position five-way solenoid valve controls the gas to be one in, two out and one exhaust (but there are three working positions); 1 air inlet (connected to the air source), 1 positive action vent hole and 1 * as a vent hole (Separate the air source provided for the target equipment in one positive and one *), 1 positive action vent and 1 ** vent (installation*).
Principle of three-way solenoid valve:
One in and one out: Normally closed (ZC2/3)—When the solenoid valve coil is energized, port 2 leads to port 1, and port 3 is closed; when the solenoid valve coil is de-energized, port 2 is closed and port 1 leads to Port 3; Normally open (ZC2/3K) When the solenoid valve coil is powered off, port 3 leads to port 1, and port 2 is closed; when the solenoid valve coil is energized, port 3 is closed, and port 1 leads to port 2;
One input and two output: (ZC2/31) When the solenoid valve coil is energized, the first circuit of the medium outlet (2) is opened and the second circuit (3) is closed; when the solenoid valve coil is de-energized, the first circuit of the medium outlet is closed. (2) Close, the second way (3) opens;
Two in and one out: (ZC2/32) When the solenoid valve coil is energized, the first circuit (2) of the medium inlet is opened, and the second circuit (3) is closed; when the solenoid valve coil is de-energized, the first circuit of the medium inlet (2) Close, and the second way (3) opens; (Check valves must be added before the two inlet ends of the inner valve)

World Famous Valve Brand Ranking

September 24, 2020

If you talk about trusted brands abroad, different valves have different manufacturers, and each imported valve

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

company is involved in different fields, and each brand has its own advantages. The explanation for imported valve brands is to let users know more about imported valve brands. It is a comprehensive selection based on the brand awareness, quality level, after-sales service, innovation ability, consumer reputation and other indicators of each imported valve company. Customers can help when purchasing imported valve products.
FISHER Fisher valve (USA), According to different requirements, Fisher valve adopts American ANSI/API, British BS, Japanese JIS, German DIN, national standard GB and other standards for design, manufacture and inspection. The main products are soda ash special valve, ceramic ball valve, clay valve, oxygen special valve, pneumatic/electric control valve, self-operated control valve, metal hard seal ball valve, high temperature butterfly valve, air separation system butterfly valve, disc valve, metal hard seal butterfly valve, thick Special valves for nitric acid, ball valves, globe valves, check valves, flat gate valves, power station valves and non-standard special valves.

Masoneilan Valve (United States), In the field of valve control, Masoneilan has set a number of firsts: the first to develop a design concept that greatly simplified the valve diameter; the first to develop the top guide and bottom guide technology of the control valve; First developed the first universal control valve (Camflex); first invented a method to reliably predict the noise during the calculation and design of the control valve.
kitz Kitzawa Valve (Japan), Kitz Kitzawa Valve (Japan) was founded in 1951 and has become one of the world’s leading integrated valve factories. The company not only produces valves for general equipment and various industrial complete sets of equipment, but also produces valves for automatic operation and testing equipment. In Beize, from casting, forging processing to assembly, serial production is carried out under strict quality management. In addition, when leaving the factory, the products are strictly inspected in accordance with the “Quality Assurance Regulations” formulated by the company, so they are well received by users all over the world.
HANK Hank Valve (Germany), HANK Hank Valve was founded in Mönchengladbach in 1852. Hank Valve is a multinational production company that is famous for producing high-quality, advanced valves, measurement and control systems. It has subsidiaries and branches in dozens of countries around the world. The main products are pneumatic valves, water supply and drainage valves, hydraulic ball valves, cryogenic valves, high temperature and high pressure valves, imported butterfly valves, imported plug valves, imported stop valves, hydraulic ball valves, imported needle valves, imported ball valves, etc.
OTTO Valve (France), The French OTTO Valve Company was established in Paris, France in 1805 and has a history of more than 100 years. At the beginning of its establishment, France OTTO Valve was only a stainless steel valve manufacturer, but now France Otto is one of the top 500 companies in the Midwest of France, with 15 manufacturing centers in the United States, Germany, the United Kingdom and Italy. Among them, 10 manufacturing centers have passed ISO9001 quality certification, and their products cover a variety of fields in the fluid control industry.
KSB Valve (Germany), Germany KSB is a world-renowned modern large company that manufactures pumps and valves. It is one of the three largest pump and valve manufacturing companies in the world. Founded in 1871, it is an international company directly managed by the headquarters. There are six factories in Germany and France. The main products of KSB in Germany include: globe valves, filters, ball valves, gate valves, traps, butterfly valves and other general valves.

Danke Valve (United States), Danke Group is the world’s leading supplier of fluid control products and services. Products designed and manufactured are used in various industrial and general commercial applications. Since its establishment for nearly a century, more than 300 dedicated engineers have continuously developed high-quality valves and accessories to meet different market needs. All products are completed under a strict quality system that complies with the ISO9001 international standard. Danke products and distributors are located in 43 countries around the world. The main products are: ball valves, gate valves, check valves, butterfly valves, etc.
ARI Valve (Germany), ARI Valve was founded in 1952 and is headquartered in STUKENBROCK, Germany. ARI has three factories in Germany. The total output of valves is second to none in Germany. The products cover four series of globe valves-safety valves-control valves-traps. In the past 50 years, German iResearch Valve has been committed to providing comprehensive technology and perfect services for industrial processes, process, chemical, shipbuilding and building automation fields, which can meet the needs of system cutoff, safety, control and Hydrophobic function requirements.
SpiraxSarco Valves (UK), SpiraxSarco Valves SpiraxSarco, UK, is committed to promoting the effective application and control of steam and other industrial fluids on a global scale. It has a history of more than 100 years. The history of SpiraxSarco Valve Company can be traced back to 1888. It was established in the United Kingdom in 1937. In 1959, SpiraxSarco Valve Group Company was listed on the London stock market and has outstanding performance reports every year.
Dongguang Valve (Taiwan), In 1962, Dongguang Faner Industrial Co., Ltd. was reorganized and moved to Hami Street, Taipei, covering an area of approximately 1,650 square meters, and adding semi-automatic casting equipment. It has a history of 60 years. Later, due to business development needs, Shenzhen Dongguang Faner Valve Co., Ltd. was officially registered in the mainland in 2010.

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
URL: http://www.tanghaivalve.com
Name: Harry Li
Email: harry@tanghaivalve.com

What is the difference between lining and vulcanized valve seat?

September 23, 2020

There are three types of rubber seat. One is a soft seat, which can be installed and removed at will. It is elastic; the other is a backrest seat, which is a hard seat. The seat is knocked into the valve by external force. The body, but it can also be disassembled, which is much more laborious than the disassembly of the soft seat; the third type is the vulcanized seat, which uses high temperature vulcanization to fix the seat to the valve body, so the vulcanized seat is sometimes called a fixed liner.
D71J is a rubber-lined valve cavity and butterfly plate are lined with rubber, D71X only the sealing surface is rubber
D71J rubber lining is that the valve body and disc plate are all covered with rubber. This is generally used for

Double flange butterfly valve (10)

corrosive media.
And D71X means rubber seal. It’s just the soft seal we are talking about. This general medium takes a lot of water. This price is also much cheaper.
The rubber lining in the rubber lining butterfly valve is to use high temperature to vulcanize the rubber and the valve body at high temperature. It has very high corrosion resistance and is generally used to control some corrosive fluids with strong acid and alkali.
The rubber butterfly valve is a butterfly valve whose seal is a rubber seal, which is generally called a valve seat, and is separately installed into a whole.
At normal temperature, the abrasion resistance of natural soft rubber is much better than that of nitrile rubber, but their high temperature resistance is the highest limit within 80 degrees, and it is not suitable for use if it exceeds 80 degrees.
The difference between fully lined butterfly valve and half lined butterfly valve:

U type flange butterfly valve (9)

1. Semi-lined butterfly valve means: the butterfly valve is not lined with rubber, and the place where the butterfly valve is connected to the valve body is lined with rubber;
2. Fully lined butterfly valve means: the butterfly plate of the butterfly valve and the part connected with the valve body are lined with rubber.
The difference between rubber lined butterfly valve, fluorine lined butterfly valve and plastic lined butterfly valve: rubber lined butterfly valve and fluorine lined butterfly valve are only one kind of plastic lined butterfly valve.
The sealing materials in the rubber-lined butterfly valve are:
Hard rubber NR applicable temperature: -10℃~85℃,
Suitable temperature of soft rubber BR: -10℃~85℃,
Suitable temperature of butyl rubber IIR: -10℃~120℃,
Applicable temperature of neoprene CR: -10℃~105℃;

The sealing materials in the fluorine-lined butterfly valve are:
Polyperfluoroethylene FEP (F46) operating temperature: -85℃~150℃,
Polytetrachloroethylene PTFE (F4) operating temperature: -200℃~180℃,
Polytrifluoroethylene PCTEF (F3) operating temperature: -195℃~120℃,
Polypropylene: RPP operating temperature: -14℃~80℃,
Polyvinyl chloride: rigid) PVC service temperature: 0℃-55℃,
Polyvinylidene chloride PVDF (F2) operating temperature: -70℃~100℃,
Polyolefin: PO Operating temperature: -58℃~80℃.

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

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