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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

The role and classification of valves

September 18, 2020

Valves have many functions. Different valves should be selected for different functions. Different types of valves have

U-type-flange-butterfly-valve-2

different structures. These functions are all means to effectively control the process and ensure safety. Valves are generally divided into automatic valves and drive valves. Automatic valves (such as safety valves, pressure reducing valves, steam traps, check valves) rely on changes in the pressure of the device or pipeline to achieve the purpose of opening and closing. Driving valves (gate valves, globe valves, ball valves, butterfly valves, etc.) rely on driving devices (manual, electric, hydraulic, pneumatic, etc.) to adjust the pressure, flow and direction of the medium in the pipeline. Due to the different pressure, temperature, flow rate and physical and chemical properties of the medium, the control requirements and use requirements of the device and piping system are also different, so the role of the valve is also different.
Classified by valve function:
Cut-off valve: The cut-off valve is also called a closed-circuit valve. Its function is to connect or cut off the medium in the pipeline. Block valves include gate valves, globe valves, plug valves, ball valves, butterfly valves and diaphragm

8 tilting-disc-swing-check-valve-3

valves.
Regulating valve: Regulating valves include regulating valves, throttle valves and pressure reducing valves, whose function is to regulate the pressure and flow of the medium.
Check valve: Check valve is also called one-way valve or check valve, its function is to prevent the medium in the pipeline from flowing back. The bottom valve of the pump to close the water is also a check valve.
Safety valve: The function of safety valves is to prevent the pressure of the medium in the pipeline or device from exceeding the specified value, so as to achieve the purpose of safety protection.
Diversion valve: Diversion valves include various distribution valves and traps, etc., whose function is to distribute, separate or mix the medium in the pipeline.
Exhaust valve: Exhaust valve is an indispensable auxiliary component in the pipeline system. It is often installed at high points or elbows to remove excess gas in the pipeline, improve the efficiency of pipeline use and reduce energy consumption.
The role of the valve: (cut-off, adjustment, check, safety)
1. Cut-off function An important function of the valve is the cut-off function. It is to cut off (shut off) the fluid in the pipeline to prevent it from circulating. Generally, the valves of various pipelines mainly play a cut-off role. To
2. Regulation function Another important function of the valve is to adjust the flow rate. According to the working conditions or use requirements, adjust the media flow, temperature, pressure, liquid level and other parameters in the pipeline. The control of this flow depends on the valve opening. To adjust the size of the degree. [Electric regulating ball valve Electric regulating butterfly valve Pneumatic regulating ball valve Pneumatic regulating butterfly valve]
3. Non-reverse function Some pipelines require the medium to flow in one direction, and no reverse flow or backflow is allowed. This requires the use of non-reverse valves (or one-way valves). It refers to a valve that automatically opens and closes the valve flaps depending on the flow of the medium itself to prevent the medium from flowing back. It is an automatic valve. Its main function is to prevent the medium from flowing back, prevent the pump and drive motor from reversing, and the container medium. put.
4. Safety function In order to prevent explosion accidents when the fluid pressure in the high-pressure container exceeds the pressure limit of the container when the pressure is too high, a valve that can automatically release pressure at a certain pressure is installed on the container, which is generally called a safety valve. For example, boilers, compressed air storage tanks and some high-pressure reactors are equipped with safety valves. This valve plays a role in ensuring safety.
5. Other functions In addition to the above four functions, the valve also has some functions, such as stabilizing the pressure of the system; reducing the high pressure in front of the valve to a lower pressure reducing effect, and releasing the pressure by venting to discharge sewage The function of sewage discharge; the sampling function of sampling for analysis and observation; and the backflow function of returning part of the fluid to the previous process. There are also steering valves (three-way valve, four-way valve, etc.) that transfer fluid to another pipeline.

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.

Valve flow characteristic curve and classification

September 18, 2020

The flow characteristic of the valve is the relationship between the relative flow of the medium flowing through the regulating valve and its opening under the condition that the pressure difference between the two ends of the valve remains constant. Flow characteristic is an important technical index and parameter of regulating valve. It is very important to make the correct selection in the application process of the control valve.

Flow characteristics of regulating valve

Valve flow characteristics can be defined as: the relative flow of the controlled medium flowing through the valve, and the relationship between the relative opening (relative displacement) of the valve is called the flow characteristics of the regulating valve. Generally speaking, it is divided into four types: straight line, equal percentage (logarithm), parabola and quick opening! The specific description and advantages are as follows:

1. The linear characteristic refers to the linear relationship between the relative flow of the valve and the relative opening, that is, the time constant of the flow change caused by the change of unit opening. The relative stroke of the linear characteristic is linear with the relative flow. The flow change caused by the change of unit stroke is constant. When the flow is large, the relative value of the flow changes little, and when the flow is small, the relative value of the flow changes greatly.

2. the equal percentage characteristic (logarithm) means that the relative flow change caused by the change of the unit opening is proportional to the relative flow at that point, that is, the amplification factor of the regulating valve changes, and it increases with the increase of the relative flow. The relative stroke and relative flow of equal percentage characteristics are not in a linear relationship. The change in flow caused by the change of unit stroke at each point of the stroke is proportional to the flow at this point, and the percentage of flow change is equal. Therefore, its advantage is that when the flow rate is small, the flow rate changes small, and when the flow rate is large, the flow rate changes greatly, that is, it has the same adjustment accuracy at different opening degrees.

3. the parabolic characteristic means that the relative flow change caused by the change of the relative opening of the unit is proportional to the square root of the relative flow value at this point. The flow rate changes in proportion to the two sides of the stroke, and generally has an intermediate characteristic between linear and equal percentage characteristics.

4. the quick opening flow characteristic means that there is a larger flow when the opening is small. With the increase of the opening, the flow can reach the maximum quickly, and then the opening is increased, and the flow change is small, so it is called For quick opening characteristics.

The flow characteristic of the diaphragm valve is close to the quick opening characteristic, the flow characteristic of the butterfly valve is close to the equal percentage characteristic, the flow characteristic of the gate valve is the linear characteristic, the flow characteristic of the ball valve is linear in the middle opening and closing stage, and the equal percentage characteristic in the middle opening.

Globe valve (9)

Under normal circumstances, ball valves and butterfly valves are usually not used for adjustment. If they are used for adjustment, they are only used for adjustment when the opening is small. Generally, they can be classified as quick-opening, and they are really used for adjustment. Most of them are basically cut-off valves (globe valve). The valve head is processed into a parabolic cone, spherical shape, etc., and different curve characteristics are used. Generally speaking, as an adjustment, the basic percentage characteristic is used more.

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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