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Comparison table of valve diameter and medium flow rate

September 14, 2020

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

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

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

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

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

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 matching function and principle of pneumatic valve accessories

September 14, 2020

Pneumatic valve is an actuator that uses compressed air to drive and operate the valve. Its opening and closing speed is relatively fast. It is often used for fast two-position cut-off and can also be used to adjust flow. Because it mainly relies on air to perform operations, so it has high practicability in flammable and explosive situations, and can be used to control gas, liquid, oil, and various corrosive media. However, there are many changes in the accessories in the pneumatic valve. With different accessories, various different control methods can not be achieved. The user can configure the corresponding valve according to the different work needs of the valve.

1. Pneumatic triplex is the most common accessory in pneumatic valves, and its function can be simply summarized

pneumatic valve structure

as: filtration + decompression + oil mist. Among them, the pressure reducing valve is a necessary accessory. The pneumatic valve of any function must be configured. Its function is to give the pneumatic valve a standard power source pressure, the standard value is 0.4-0.7MPa. The pressure reducing valve is a valve that reduces the inlet pressure to a certain required outlet pressure through adjustment, and relies on the energy of the medium itself to automatically maintain a stable outlet pressure. a. The role of the two-piece (filter, pressure reducing valve): complete the filtering and pressure-reducing function of the compressed instrument air b. The role of the three-piece (filter, pressure reducing valve, oil mist device): complete the function of the compressed instrument air Filtering and decompression function, and lubricate the air.

2. The pneumatic solenoid valve can also be called a directional control valve. For two-position valves that only need to be opened and closed, the solenoid valve is a necessary configuration. The solenoid valve achieves the on/off control of the pneumatic valve through excitation/demagnetization. Solenoid valves are often used to switch valves, and control the on and off of the air source and air circuit through voltage signals to control the opening and closing of the valve. Definition: A valve that uses an electromagnet to control the spool movement generally realizes the opening and closing of the valve by controlling the movement process of the pneumatic actuator.

3. The valve limit switch, also called the travel switch, can also be called the echo device. It is a field instrument for

Limit switch-valve

detecting valve status in the automatic control system. It is used to output the open or closed position of the valve as a switch (contact) signal, which is accepted by the program controller or the computer searches for sampling, and executes the next program after confirmation. The product can also be used for interlocking protection of important valves in the system and remote alarm indication. If you want to grasp the valve position status of the two-position valve, the valve limit switch is an effective configuration, which is an electrical switch used to indicate and feedback the limit position of the mechanical equipment.

4. Valve positioner, it is a necessary configuration for pneumatic control valves. The valve positioner can be used to control the position of the valve at any opening degree. It uses the valve stem displacement signal as the input feedback measurement signal and the controller output signal as the setting Signal, compare, when there is a deviation between the two, change its output signal to the actuator, make the actuator act, and establish a one-to-one correspondence between the valve stem displacement times and the controller output signal.
Note: If it is a regulating valve controlled by a safe condition, a solenoid valve must also be configured. The solenoid valve is used to force the valve to be in a safe valve position under unexpected conditions.

For large-capacity cylinder valves, in order to speed up the valve action, the pilot valve must also be configured. The role of the pilot valve is to drive the pilot valve with a small gas signal to switch the atmospheric pipeline, so that the cylinder valve has a better performance. There are many types of pilot valves for fast charging/discharging gas circuits, which should be selected according to the specific needs of pneumatic valves.

If the valve position to be mastered is a regulating valve, a valve opening transmitter must be installed, which can feed back the opening signal of the valve at any position. Due to the requirements of the equipment and technology, the valve may open normally, slowly close, or slowly open, and normally close, then a pneumatic damper is required. The damper is to control the amount of air flow through and adjust to achieve the required valve action speed.

The difference and application of stainless steel 430, 304, 316

September 14, 2020

Stainless steel 430, 304,316 are the material of valve body, valve stem/shaft, or valve disc/plate.

lug type butterfly valve body

430 ferritic stainless steel containing more than 12% chromium can prevent oxidation caused by natural factors. It is called stainless steel. It belongs to 430 ferritic stainless steel. It has low thermal expansion rate, excellent formability and oxidation resistance. The code name in JIS is 430, so it is also called 430 stainless steel.

Application of 430 ferritic stainless steel: 430 stainless steel (16Cr) is often used to make household appliances, heat-resistant appliances, burners, home appliances, class 2 tableware, kitchen sinks, exterior decoration materials, bolts, nuts, CD rods, screens .

The difference between 430 stainless steel and 304, 316 austenitic stainless steel: 430 stainless steel and 304, 316 austenitic stainless steel are identified by spectral analysis and chemical element analysis. Both 304 and 316 are austenitic stainless steels. 316 is made of 304 stainless steel with molybdenum added. Therefore, 316 stainless steel has much better seawater and rust resistance than 304.
The difference between 304, 316 and 430 lies in the rust resistance. In addition to chromium, 304 and 316 also contain elements such as nickel and molybdenum, and are non-magnetic. Therefore, the rust resistance of 304/316 austenitic stainless steel is better than 430 stainless steel is much better and the price is much higher. To

Can the 430 stainless steel magnet hold it? 304 and 316 are not magnetic and cannot be attracted by magnets. Generally, it does not generate heat in a high-voltage electromagnetic environment, so it is used more. Martensitic and 430 ferritic stainless steel, precipitation hardening stainless steel are magnetic, and magnets can attract them.

Will 430 stainless steel rust? 430 stainless steel cannot resist the oxidation caused by chemicals in the air. Because there are more and more acidic chemicals in the air, 430 stainless steel will still be oxidized (rusted) due to unnatural factors after being used for a period of time.

Which is better, 430 stainless steel or 304? 304 austenitic stainless steel has excellent corrosion resistance and no magnetism. Relatively speaking, austenitic stainless steel 304 is better than 430 ferritic stainless steel.

How expensive is 430 stainless steel compared to 304? Generally speaking, austenitic stainless steel 304 is twice as expensive as 430 stainless steel.

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

Principles of valve selection in the petroleum and chemical industry

September 14, 2020

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

lug type butterfly valve, ductile iron, center lined,

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

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

Globe valve (9)

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

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

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

TH Valve is a professional manufacturer of butterfly 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

Chinese marine valve product standard encyclopedia

September 14, 2020

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

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

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

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

TH Valve is a professional manufacturer of butterfly 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

Description of valve pressure& installation direction requirements

September 14, 2020

As the name implies, the pressure of the valve refers to the pressure that the valve can withstand, that is, the

double-wing-check-valve-3

pressure level of the valve is not lower than the design pressure level of the pipeline. The pressure-bearing direction refers to the closed state of the valve after the valve is applied to the pipeline conditions. The arrow direction of the valve body is the recommended pressure-bearing direction. If it is installed incorrectly, the leakage failure of the valve may not be tightly closed. Generally, it is determined according to the use process or usage conditions. The same direction refers to the pressure-bearing direction (the side with high medium pressure on both sides of the valve gate) and the flow direction, and the opposite direction refers to the pressure-bearing direction (both sides of the valve gate) The side with high medium pressure) is opposite to the flow direction of the medium.

Many valves are directional, such as stop valves, throttle valves, pressure reducing valves, check valves, etc. If they are installed upside down, they will affect the use effect and life (such as throttle valves), or they will not work at all (such as Pressure reducing valve), or even cause danger (such as check valve). Normal valves have direction signs on the valve body; if not, they should be correctly identified according to the working principle of the valve.

The arrow marked on the valve body is the recommended pressure direction of the valve, not the flow direction of the pipeline medium. Valves with two-way sealing function may not be marked with an indicating arrow, or with an arrow, because the valve arrow refers to the recommended pressure direction. It is better to have one direction in the left and right or up and down directions. Usually used by the engineering installation company as the medium flow direction to mark the wrong installation, resulting in leakage or even pipeline accidents;

The valve cavity of the shut-off valve is asymmetrical left and right. The fluid must pass through the valve port from bottom to top, so that the fluid resistance is small (determined by the shape), and the opening is labor-saving (because the medium pressure is upward), and the medium does not press the packing after closing, which is convenient for maintenance . This is the reason why the globe valve cannot be reversed. Other valves also have their own characteristics. The location of the valve installation must be convenient for operation; even if the installation is temporarily difficult, it is necessary to consider the long-term work of the operator. It is best to keep the valve handwheel flush with the chest (usually 1.2 meters away from the operating floor), so that it is easier to open and close the valve. The hand wheel of the floor valve should be upward, not tilted, to avoid awkward operation. To

The valve of the wall machine and the equipment should also leave room for the operator to stand. It is necessary to avoid operating from the sky, especially acid and alkali, toxic media, etc., otherwise it is very unsafe. Do not install the gate valve upside down (that is, the handwheel is downward), otherwise the medium will remain in the valve cover space for a long time, which will easily corrode the valve stem, and it is contraindicated by certain process requirements. At the same time, it is extremely inconvenient to replace the packing. The exposed stem gate valve should not be installed underground, otherwise the exposed stem will be corroded due to moisture. When installing the lift check valve, ensure that its valve flap is vertical for flexible lifting. For the swing check valve, ensure that its pin shaft is level during installation to allow flexible swing. The pressure reducing valve should be installed upright on a horizontal pipe, and not inclined in all directions.

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

What are the main factors affecting valve sealing?

September 11, 2020

Valve leakage is very common in daily life and industrial production, and the impact is very large. It will cause waste or bring danger to life. For example, the leakage of tap water valve will lead to serious consequences, such as the

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

chemical industry. Toxic, harmful, flammable, explosive and corrosive media leakage, etc., serious threats to personal safety, property safety and environmental pollution accidents. A valve that relies on external force to rotate and drive to open and close is designed with a sealing device. It is used to install a certain number of packing seals in the packing culvert to achieve a sealing effect, but how about the sealing? Leakage at the packing of the valve is one of the most prone to leakage failure in the valve, but the reasons are largely the following reasons.

1. The structure of the sealing pair

The structure of the sealing pair will change when the temperature or sealing force changes. Moreover, this change will affect and change the mutual force between the sealing pairs, thereby reducing the performance of the valve sealing. Therefore, when choosing a seal, be sure to choose a seal with elastic deformation. At the same time, pay attention to the width of the sealing surface. The reason is that the contact surfaces of the sealing pair cannot be completely matched. When the width of the sealing surface increases, the force required for sealing must be increased.

2. The specific pressure of the sealing surface

The specific pressure of the sealing surface affects the sealing performance of the valve and the service life of the valve. Therefore, the specific pressure of the sealing surface is also a very important factor. Under the same conditions, too much specific pressure will cause damage to the valve, but too little wine will cause valve leakage. Therefore, we need to fully consider the appropriateness of the specific pressure when designing.

3. The physical properties of the medium

The physical properties of the medium also affect the sealing performance of the valve. These physical properties include temperature, viscosity and surface hydrophilicity. The temperature change not only affects the slackness of the sealing pair and changes in the size of the parts, but also has an inseparable relationship with the viscosity of the gas. The gas viscosity increases or decreases as the temperature increases or decreases. Therefore, in order to reduce the influence of temperature on the sealing performance of the valve, when we design the sealing pair, we must design it into a valve with thermal compensation such as an elastic valve seat. Viscosity is related to the permeability of the fluid. When under the same conditions, the greater the viscosity, the smaller the permeability of the fluid. The hydrophilicity of the surface means that when there is a thin film on the metal surface, the thin film should be removed. Because this thin oil film will destroy the hydrophilicity of the surface and block the fluid channel.

4. The quality of the sealing pair

The quality of the sealing pair mainly refers to the selection, matching, and manufacturing accuracy of materials. For example, the valve disc and the sealing surface of the valve seat are very consistent, which can improve the sealing performance. The characteristic of many hoop waviness is its good labyrinth sealing performance.

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 main classification and use conditions of valve sealing materials

September 10, 2020

The valve seal is the most important part of the entire valve. Its main purpose is to prevent leakage. The valve sealing

soft sealing marine valve, rubber sealing, valve seat parts

seat is also called a sealing ring. It is an organization that directly contacts the medium in the pipeline and prevents the medium from flowing. When the valve is in use, there are a variety of different media in the pipeline, such as liquid, gas, oil, corrosive media, etc., and different valve seals are used in different places and can adapt to various medium.
Then, valve seal materials can be divided into two major categories, namely, metallic materials and non-metallic materials. Non-metallic seals are generally used for pipelines at room temperature and pressure, while metal seals are widely used and can be used for high temperature and high pressure!
The following briefly introduces the use conditions of various sealing materials and the commonly used valve types.

1. Synthetic rubber
Synthetic rubber is better than natural rubber in oil resistance, temperature resistance and corrosion resistance. Generally, the use temperature of synthetic rubber t≤150℃, natural rubber t≤60℃, and rubber is used for the sealing of stop valves, gate valves, diaphragm valves, butterfly valves, check valves, pinch valves and other valves with a nominal pressure of PN≤1MPa. Commonly used types of synthetic rubber: NBR, EPDM, VITON.
2. Nylon
Nylon has the characteristics of low friction coefficient and good corrosion resistance. Nylon is mostly used for ball valves and globe valves with temperature t≤90℃ and nominal pressure PN≤32MPa.
3. Polytetrafluoroethylene Polytetrafluoroethylene is mostly used for globe valves, gate valves, and ball valves with a temperature t≤232℃ and a nominal pressure of PN≤6.4MPa. Short name: PTFE
4. Cast iron
Cast iron is used for gate valves, stop valves, cock valves, etc. for temperature t≤100℃, nominal pressure PN≤1.6MPa, gas and oil. main types: GI, DI
5. Babbitt alloy
Babbitt alloy is used for ammonia stop valves with temperature t-70~150℃ and nominal pressure PN≤2.5MPa.
6. Copper alloy
Commonly used copper alloy materials include 6-6-3 tin bronze and 58-2-2 manganese brass. Copper alloy has good wear resistance, suitable for water and steam with temperature t≤200℃ and nominal pressure PN≤1.6MPa. It is often used in gate valves, globe valves, check valves, plug valves, etc.
7. Chromium stainless steel
Commonly used grades of chromium stainless steel are 2Cr13 and 3Cr13 after quenching and tempering treatment, which has good corrosion resistance. It is commonly used on valves of water, steam, petroleum and other media with temperature t≤450℃ and nominal pressure PN≤32MPa.
8. Chromium nickel titanium stainless steel
The commonly used grade of chromium nickel titanium stainless steel is 1Cr18Ni9ti, which has good corrosion resistance, erosion resistance and heat resistance. It is suitable for steam, nitric acid and other media with temperature t≤600℃ and nominal pressure PN≤6.4MPa, used in stop valves, ball valves, etc.
9. Nitrided steel
The commonly used grade of nitriding steel is 38CrMoAlA, which has good corrosion resistance and scratch resistance after carburizing treatment. Commonly used for power station gate valves with temperature t≤540℃ and nominal pressure PN≤10MPa.
10. Boronizing
Boronizing is directly processed from the valve body or valve clack body material to form the sealing surface, and then boronizing surface treatment, the sealing surface has good wear resistance. Used in power station blowdown valves. To
When the valve is in use, the matters that should be paid attention to are:
1. The sealing performance of the valve should be tested to ensure its performance.

2. Check whether the sealing surface of the valve is worn, and repair or replace it according to the situation.

Valve material and valve standards-(9)- general valve & parts materials

September 9, 2020

General valve material
The internal material combination specified by API600 for general valve material:

Stem material types	hardness	sealing surface
Stem material types	hardness	seal part no.,	material type	hardness
13Cr	200-275	1	13Cr	≥HB250
		4	13Cr	≥HB750
		5 or 5A	HF	≥HB350
		6	13Cr/NiCu	≥HB750/≥HB175
		7	13Cr/13Cr	≥HB250/≥HB750
		8-8A	13Cr/HF	≥HB250/≥HB350
18Cr-8Ni	no require	2	18Cr-8Ni	no require
25Cr-20Ni		3	25Cr-20Ni
Nickel copper alloy		9	Nickel copper alloy
Nickel copper alloy		11 or 11A	Nickel copper alloy/HF	no require/≥HB350
18Cr-8Ni-Mo		10	18Cr-8Ni-Mo	no require
18Cr-8Ni-Mo		12 or 12A	18Cr-8Ni-Mo/HF	no require/≥HB350
19Cr-29Ni		13	19Cr-29Ni/HF	no require
19Cr-29Ni		14 or 14A	19Cr-29Ni/HF	no require/≥HB350

Commonly used valve trim material combination:

valve stem	sealing surface	valve stem	sealing surface
13Cr	13Cr/13Cr	321	321/321
13Cr	13Cr/STL	321	321/STL
13Cr	STL/STL	321	STL/STL
13Cr	13ZCr/Monel	1Cr18Ni9Ti	1Cr18Ni9Ti/1Cr18Ni9Ti
17-4PH	STL/STL	1Cr18Ni9Ti	1Cr18Ni9Ti/STL
17-4PH	17-4PH/17-4PH	1Cr18Ni9Ti	STL/STL
Monel	Monel/Monel	1Cr18Ni12Mo2Ti	1Cr18Ni12Mo2Ti/1Cr18Ni12Mo2Ti
304	304/304	1Cr18Ni12Mo2Ti	1Cr18Ni12Mo2Ti/STL
304	304/STL	1Cr18Ni12Mo2Ti	STL/STL
304	STL/STL	20 Alloy	20alloy/20alloy
316	316/316	Hastelloy B	Hastelloy B/Hastelloy B
316	316/STL	Hastelloy C	Hastelloy C/Hastelloy C
316	STL/STL	F51	F51/F51
304L	304L/304L	F51	F51/STL
304L	304L/STL	38CrMoALA	STL/STL
304L	STL/STL	25Cr2MoIV A	STL/STL
316L	316L/316L	4Cr10Si2Mo	STL/STL
316L	316L/STL	4Cr14Ni14W2Mo	STL/STL
316L	STL/STL	Inconel	Inconel/Inconel

Commonly used fastener material:

Bolts	Nuts	Max temp °C
35	25	425
35CrMo	35, 45	425
35CrMo	30CrMo	500
25Cr2MoVA	30CrMo	550
0Cr18Ni9	0Cr18Ni9	600
0Cr17Ni12Mo2	0Cr17Ni12Mo2	600
25Cr2Mo1VA	25Cr2Mo1VA	600
25Cr2MoVA	25Cr2MoVA	600

Matching materials of bolts and nuts for American standard valves:

Bolts		nuts		application temp
standard	grade name	standard	grade name	application temp
ASTM A193	B7	ASTM A194	2H	-29/425°C
	B7M		2HM	-29/425°C NACE standard, anti-sulfer valve
	B16		7	-29/593°C
	B8		8	-196/700°C
	B8M		8M	-196/700°C
ASTM A320	L7		4	-46/101°C Cryogenic valve

Chemical composition and mechanical properties of commonly used bolts and nuts for American standard valves:

Chemical composition and mechanical properties of commonly used bolts and nuts for American standard valves

Conditions of use of metal gaskets:

material	HB max	Pressure Mpa(lb)	suitable temp °C
10/08	120	2.0-42(150-2500)	450
0Cr13	170	2.0-15(150-900)	540
0Cr18Ni9	160		600
0Cr17Ni12Mo2	160		600

Spiral wound gasket service conditions:

metal belt material	Non-metallic belt material	Pressure grade Mpa (lb)	suitable temp °C
0Cr18Ni9	flexible graphite	2.0-26(150-1500)	650
0Cr17Ni12Mo2	flexible graphite		650
00Cr17Ni14Mo2	PTFE		200

Conditions for use of metal-clad gasket:

Cladding metal material	HB	filling material	pressure Mpa(lb)	suitable temp °C
Al L3	40	asbestos	2.0-15(150-900)	200
Co T3	60			300
Galvanized steel sheet	90			400
Galvanized steel sheet 08F	90			400
0Cr18Ni9	187			500
00Cr19Ni10
00Cr17Ni14Mo2

Use conditions of flexible graphite composite gasket:

Core board and edging material	pressure grade Mpa (lb)	suitable temp °C
low-carbon steel	2.0-11(150-600)	450
0Cr18Ni9	2.0-11(150-600)	650

Non-metallic gasket usage conditions:

material name	code name	pressure Mpa	suitable temperature °C
natural rubber	NR	2.0	-50/90
Neoprene	CR	2.0	-40/100
NBR	NBR	2.0	-30/110
Ethylbenzene rubber	SBR	2.0	-30/110
EPDM rubber	EPDM	2.0	-40/130
fluororubber	Viton	2.0	-50/200
Asbestos Rubber Sheet	XB350 XB450 NY400	2.0 ≤300 P.T≤650 Mpa °C
Oil-resistant asbestos rubber sheet	XB350 XB450 NY400	2.0 ≤300 P.T≤650 Mpa °C
Modified or filled with PTFE		5.0	-196/260

Comparison table of common metal materials specified by Chinese, Japanese, German, British, American and international standards:

Comparison table of common metal materials specified by Chinese, Japanese, German, British, American and international standards

WC carbon steel +A/B/C –WCA,WCB,WCC

WC carbon steel +ABC –WCA,WCB,WCC

Please see the Full documentation at this link: https://www.tanghaivalve.com/wp-content/uploads/2020/09/valve-material-and-valve-standards-Detailed-version.pdf

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 material and valve standards-(8)- Monel alloy application

September 7, 2020

4. Application of Monel alloy:
The A and E levels of M35-1, M35-2 and QQ-N2-88 are usually used to manufacture refined Monel alloy pumps,

buttefly valve stem shaft parts (6)

valves and accessories. The B-grade (3.5%Si) Monel alloy with the highest Si content is mainly used to manufacture shafts and wear-resistant rings that require good wear resistance due to its high strength, corrosion resistance and wear resistance. Class D (4.0% Si) Monel alloy is used to manufacture parts that require higher wear resistance and corrosion resistance.
Monel alloy valves have two types: integral and internal. The integral Monel alloy valve means that the valve shell and internal parts are all Monel, which is mainly used in the HF acid regeneration tower part of the alkylation unit of the refinery. Due to the high HF acid regeneration temperature (149°C) and high water content, an overall alloy valve is required. In addition, the overall Monel alloy valve is also used in the production of ashless additives for catalysts in refineries and high-concentration chlor-alkali systems in chlor-alkali plants. Situation.
The Monel alloy internal valve means that the valve housing is made of carbon steel or stainless steel, and the internal valve is made of Moenl alloy. The Monel alloy valve with carbon steel as the shell is mainly used in the low temperature area of the HF calculation system of the alkylation unit of the refinery. The use of carbon steel is good for low temperature (≤71°C) anhydrous hydrofluoric acid (HF) However, carbon steel will form a film on its surface due to corrosion when used in this working condition for a long time. If carbon steel is used in the valve sealing part, the film formed after corrosion will affect the sealing performance of the valve. It should be pointed out that the commonly used Cr13 type sealing material for carbon steel valves cannot resist the corrosion of HF acid, and the internal material is much cheaper for Monel alloy valves. The Monel alloy valve with carbon steel as the shell can also be used in working conditions such as sea water. The valve housing is made of stainless steel Monel alloy internal valve, which is used in ethylene, propylene, liquid oxygen, pure oxygen, sea water and other working conditions. The monolithic Monel alloy valve and Monel alloy internal valve used in the alkylation unit require a pressure level of CL300 from a safety point of view. The pressure level of Monel alloy internal valve for other working conditions is CL150 and CL300. Or PN116-614Mpa etc.
5. Melting and casting of monel alloy:
The smelting and casting technology of Monel alloy is the key to determine whether the qualified Monel alloy castings can be produced. Because Moenl alloy has developed dendrites, shrinkage cavities and porosity, the tendency of gas absorption (hydrogen absorption, oxygen absorption) is great, and it will Sulfurizing chemical reaction occurs with molding materials. From a safety point of view, Monel alloy valves are required to undergo radiographic inspection in accordance with Class A pipeline valves in highly toxic and dangerous media such as hydrofluoric acid, chlorine and hydrogen chloride gas. . Although the American standard points out that casting M35-1 can be welded, in fact its weldability is extremely poor, and the quality of repaired castings is difficult to guarantee. The density of M35-1 alloy is 8163t/m3 (at 20°C), the solidification shrinkage rate is 21mm/m, and the alloy melting point is 1315-1345°C. The Class A and Class E of M35-1, M35-2 and QQ-N2-88 are delivered as cast. Although there are many grades of cast Monel alloy, when used to cast Monel alloy valve castings, M35-1 in ASTMA494 is mainly used.
Cast Monel alloy and deformed Monel alloy have little change in chemical composition (Table 4), but this change satisfies its better deformability for deformation and gold, while it provides better casting for cast alloys. performance. This is the reason why cast Monel alloy grades are used when casting, and deformed Monel alloy grades are used when selecting rolling materials.
Table 4. Commonly used cast and deformed Monel alloy chemical composition of valves (%)

Grade name	chemical composition /%
Grade name	C	Mn	Si	P	S	Cu	Fe	Ni	others
M35-1	≤0.35	≤1.5	≤1.25	≤0.03	≤0.03	26-33	≤3.5	Ba
Monel400	≤0.30	≤2.0	≤0.5		≤0.024	Ba	≤2.5	63-70
MonelK500	≤0.25	≤1.5	≤0.5		≤0.01	Ba	≤2.0	63-70	Al2.5-3.5, Ti0.35-0.85

6. Conclusion
The current U.S. technical standards for Monel alloys include ASTM, SAE, AMS (American Aeronautical Standards Institute), MIL (U.S. Department of Defense Standards), ANSI, ASME and QQ (American Federal Standards). For the Monel alloy of the same grade, different technical specification systems are adopted, not only the representation method of the grade is different, but the number and content of the specification are not completely the same. Usually military products use MIL, QQ or AMS specifications, and civil products use ASTM and ASME specifications.

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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