supplier Archives

Valve actuator / actuation -(4)-angle stroke valve actuator application

August 19, 2020

Angle stroke valve actuator application products:

1. Butterfly valve:
The baffle of the butterfly valve controls the flow of fluid with the rotation of the shaft. It is composed of valve body, baffle, baffle shaft and shaft seal. Its simple structure, small size, light weight, low cost and large flow capacity are especially suitable for occasions with low pressure difference, large diameter, large flow gas and fluid with su

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

spended solids, but the leakage is large. Its flow characteristics are achieved at the corners. The front and equal percentage characteristics are similar, but the work will be unstable and the characteristics will not be good in the future; use in the corner range. Butterfly valves are not only widely used in general industries such as petroleum, gas, chemical, and water treatment, but also used in cooling water systems of thermal power stations.

2. Ball valve:
The ball valve is defined in the standard GB/T21465-2008 “Valve Terminology” as a valve in which the opening and

closing part (sphere) is driven by the valve stem and rotates around the axis of the valve stem. The ball valve has a 90-degree rotation. The cock body It is a sphere with a circular through hole or channel passing through its axis. It is mainly used to cut off or connect the medium in the pipeline, and can also be used for fluid adjustment and control. Among them, the hard-sealed V-shaped ball valve has a strong shear between the V-shaped core and the metal seat of the hard alloy. Shearing force is especially suitable for media containing fibers and tiny solid particles. The multi-way ball valve can not only flexibly control the confluence, divergence, and flow direction switching of the

14 ball-valve-6

medium in the pipeline, but also close any channel and connect the other two channels. This type of valve should generally be installed horizontally in the pipeline. Ball valve classification: pneumatic ball valve, electric ball valve, manual ball valve. The ball valve can be closed tightly with only a 90-degree rotation and a small torque. The ball valve is most suitable for use as a switch and shut-off valve, V-shaped ball valve. In the developed western countries, the use of ball valves is increasing year by year. In our country, ball valves are widely used in petroleum refining, long-distance pipelines, chemicals, papermaking, pharmaceuticals, water conservancy, electric power, municipal administration, steel and other industries. Occupy a pivotal position in the national economy.

3. Cam flex valve:

Cam flex valve, also known as eccentric rotary valve, is also a new-type regulating valve. The center line of the spherical valve core deviates from the center of the rotating shaft, and the rotating shaft drives the valve core to rotate eccentrically, so that the valve core enters the valve seat forward and downward.

The eccentric rotary valve has the advantages of small size, light weight, reliable use, convenient maintenance, strong versatility, and low fluid resistance. It is suitable for occasions with high viscosity and has good performance in lime, mud and other fluids.

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 actuator / actuation -(3)-classifications

August 19, 2020

Double acting valve actuator:
The selection of double-acting actuators takes DA series pneumatic actuators as an example. The output torque of

Pneumatic actuator (2)

the gear-and-pinion actuator is the piston pressure (supplied by the air source pressure) multiplied by the pitch circle radius (arm). And the friction resistance is small and the efficiency is high. The output torque is linear when rotating clockwise and counterclockwise. Under normal operating conditions, the recommended safety factor for double-acting actuators is 25-50%

Single-acting valve actuator:
The selection of single-acting actuator takes the SR series pneumatic actuator as an example. In the application of spring return, the output torque is obtained during two different operations. According to the stroke position, each operation produces two different torque values. The output torque of the spring-return actuator is obtained by multiplying the force (air pressure or spring force) by the force arm. The first situation: the output torque is obtained by air pressure entering the central cavity to compress the spring, which is called “air stroke output torque”. In this case, the air source pressure forces the piston to turn from 0 degrees to 90 degrees. Due to the reaction force generated by the compression of the spring, the torque gradually decreases from the maximum value

hydraulic actuator for marine valve

at the starting point to the second condition: the output torque is the spring recovery when the middle cavity loses air. The force acting on the piston is called “spring stroke output torque”. In this case, due to the extension of the spring, the output torque gradually decreases from 90 degrees to 0 degrees. As mentioned above, the single-acting actuator is based on two It is designed on the basis of generating a balance torque under this condition.

Linear valve actuator:
1. Through single seat valve

The so-called single seat means that there is only one valve core and one valve seat in the valve body. Its characteristics are simple structure, small leakage (even completely cut off) and small allowable pressure difference. Therefore, it is suitable for occasions requiring clean media with small leakage and small working pressure difference. Special attention should be paid to the allowable pressure difference in the application to prevent the valve from closing.

2. Straight through double seat valve

There are two valve cores and valve seats in the valve body of the straight-through double-seat regulating valve. Compared with the single seat valve of the same caliber, its flow capacity is about 20% to 25% larger. Because the force of the fluid on the upper and lower valve cores can cancel each other, but the upper and lower valve cores are not easy to close at the same time, the double seat valve has the characteristics of large allowable pressure difference and large leakage. Therefore, it is suitable for clean media where the pressure difference between the two ends of the valve is large and the leakage requirement is not high. It is not suitable for high viscosity and fiber-containing occasions.

3. Angle valve

The valve body of the angle control valve is right-angled, its flow path is simple, and the service force is small. It is suitable for the control of high pressure difference, high viscosity, suspended solids and granular materials. Generally used for bottom inlet and side outlet, this kind of control valve has better stability. In high pressure situations, in order to prolong the service life of the spool, the side inlet and the bottom outlet can be used, but oscillation is prone to occur in small openings.

Classification of valves

August 18, 2020

Valve classification by function and purpose:

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

(1) Cut-off type: such as gate valve, globe valve, plug valve, ball valve, butterfly valve, needle valve, diaphragm valve, etc. The cut-off valve is also called a closed-circuit valve or a cut-off valve, whose function is to connect or cut off the medium in the pipeline.

Check valve, also known as one-way valve or check valve, check valve is an automatic valve, its function is to prevent the back flow of the medium in the pipeline, prevent the pump and drive motor from reversing, and the leakage of the container medium . The bottom valve of the pump to close the water is also a check valve.

Explosion-proof valves, emergency valves, etc. The role 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.

Regulating valve, throttle valve and pressure reducing valve, its role is to adjust the pressure, flow and other parameters of the medium.

(2) Vacuum: such as vacuum ball valve, vacuum baffle valve, vacuum charging valve, pneumatic vacuum valve, etc. Its role is in the vacuum system to change

The vacuum system components that adjust the air flow direction, cut off or connect the pipeline are called vacuum valves.

(3) Special purpose categories: such as pigging valve, vent valve, drain valve, exhaust valve, filter, etc. The exhaust valve is an indispensable auxiliary component in the pipeline system, which is widely used in boilers, air conditioners, oil and gas, and water supply and drainage pipelines. 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.

According to the main parameters:

According to the nominal pressure:

lug type butterfly valve, ductile iron, center lined,

(1) Vacuum valve: refers to a valve whose working pressure is lower than the standard atmospheric pressure.
(2) Low pressure valve: refers to the valve with a nominal pressure PN ≤ 1.6Mpa.
(3) Medium pressure valve: refers to valves with nominal pressure PN of 2.5Mpa, 4.0Mpa, 6.4Mpa.
(4) High-pressure valve: refers to the valve whose nominal pressure PN is 10.0Mpa~80.0Mpa.
(5) Ultra-high pressure valve: refers to a valve with a nominal pressure PN≥100.0Mpa.
(6) Filter: Refers to the nominal pressure PN is 1.0Mpa, 1.6Mpa

According to working temperature

(1) Ultra-low temperature valve: used for valves with medium working temperature t<-101℃.
(2) Normal temperature valve: used for valves with medium working temperature -29℃<t<120℃.
(3) Medium temperature valve: used for valves with a working temperature of 120℃<t<425℃.
(4) High temperature valve: used for valves with medium working temperature t>425℃.

By driving method:

According to the driving mode, it is divided into automatic valves, power-driven valves and manual valves

Valves driven by compressed air. Hydraulic valve: A valve driven by the pressure of liquids such as oil.

In addition, there are combinations of the above several driving methods, such as pneumatic-electric valves.

According to the nominal diameter:

(1) Small diameter valve: Valve with nominal diameter DN≤40mm.
(2) Middle diameter valve: a valve whose nominal diameter DN is 50~300mm.
(3) Large diameter valve: a valve with a nominal valve DN of 350~1200mm.
(4) Extra large diameter valves: valves with nominal diameter DN ≥ 1400mm

6. According to structural characteristics:

Valve structure characteristics:

The structural features of the valve can be divided into:

(1) Sectional gate shape: The closing part moves along the center of the valve seat; such as a globe valve
(2) Cock and ball: The closing part is a plunger or a ball, which rotates around its own centerline; such as a plug valve, a ball valve
(3) Gate shape: The closing part moves along the center of the vertical valve seat; such as gate valve, gate, etc.
(4) Swing shape: The closing part rotates around the axis outside the valve seat; such as swing check valve, etc.
(5) Butterfly shape: the disc of the closing part, which rotates around the axis in the valve seat; such as butterfly valve, butterfly check valve, etc.
(6) Slide valve shape: The closing piece slides in a direction perpendicular to the channel. Slippery

Press connection method:

(1) Threaded connection valve: The valve body has an internal thread or an external thread, which is connected with the pipe thread…
(2) Flange connection valve: The valve body has a flange and is connected to the pipeline flange.
(3) Welding connection valve: The valve body has a welding groove and is welded to the pipeline.
(4) Clamp connection valve: The valve body has a clamp, which is connected with the pipe clamp.
(5) Ferrule connection valve: the ferrule is connected to the pipeline.
(6) Wafer connection valve: a connection form in which the valve and two pipes are directly clamped together with bolts.

According to the body material

(1) Metal material valve: its valve body and other parts are made of metal material. Such as cast iron valves, cast steel valves, alloy steel valves, copper alloy valves, aluminum alloy valves, lead alloy valves, titanium alloy valves, Monel alloy valves, etc.
(2) Non-metallic material valve: its valve body and other parts are made of non-metallic material. Such as plastic valves, enamel valves, ceramic valves, FRP valves, etc.

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

Installation attentions for valves

August 18, 2020

Precautions for valve installation:

Globe valves, throttle valves, pressure reducing valves, check valves and other valves are all directional. If the throttle valve is installed upside down, it will affect the use effect and life. If the pressure reducing valve does not work at all, if it is stopped The return valve can even cause danger.

lift-swing-check-valve-2

Generally, the valve has a direction mark on the valve body; if not, it should be correctly identified according to the working principle of the valve.

The valve cavity of the shut-off valve is asymmetrical left and right, and 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 (due to the upward pressure of the medium), 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 valve installation location 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 hand wheel flush with the chest (usually 1.2 meters away from the operating floor), so that opening and closing the valve is easier. The hand wheel of the floor valve should be upward, do not tilt, to avoid

Globe valve (9)

awkward operation. 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 down), otherwise the medium will remain in the valve cover space for a long time, which will easily corrode the valve stem, and it is taboo for certain process requirements. At the same time, it is extremely inconvenient to replace the packing.

1. The pressure reducing valve should be installed upright on the horizontal pipeline, and not inclined in all directions.

2. As for the lift check valve, make sure its valve flap is vertical when installing it so that it can be lifted flexibly.

3. Swing check valve, ensure that its pin shaft is level when installing, so that it can swing flexibly.

4. Do not install the rising stem gate valve underground, otherwise the exposed stem will be corroded due to moisture.

Tianjin Tanghai Valve Manufacturing Co., Ltd. is one of the largest butterfly valve manufacturers in China, main products are butterfly valves, check valves, gate valve and globe valves. Key words: butterfly valve, lug type butterfly valve, wafer type butterfly valve, U-type butterfly valve, double flange butterfly valve, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…)

Current status and development of Chinese valves

August 18, 2020

Domestic status: In terms of technical support for valve production and R&D, domestic valves are not lagging behind foreign valves. On the contrary, many products are comparable to international companies in terms of technology

lug type butterfly valve-ductile iron

and innovation. The development of the domestic valve industry should move towards high-end modernization.

Driven by the four major forces of industrialization, urbanization, reform and globalization, the prospects of my country’s valve equipment manufacturing industry are still broad. In the future, high-end, localization, and modernization of the valve industry will be the main development direction of the valve industry in the future. Pursuing continuous innovation and creating a new market for valve companies can enable companies to survive and develop in the increasingly competitive pump and valve industry.

With the continuous development of valve technology and the continuous expansion of valve application fields, corresponding valve standards are becoming more and more indispensable. The valve industry products have entered a period of innovation. Not only the product categories need to be updated, but the internal management of the enterprise also needs to deepen the reform according to the industry standards.

Therefore, it is necessary to make full use of existing standards while looking forward to the future, and to develop new standards and new systems that can be used in the future, so as to promote the higher-level development of valve technology. In the future, the valve industry will develop in two main directions: one is to develop from a single variety to multiple varieties and specifications; the other is to develop in the direction of energy saving.

According to industry insiders, pump and valve companies can only effectively and clearly understand the status quo of the industry, continuously strengthen and optimize their products, strengthen their awareness of danger, strengthen corporate culture and market service concepts, and only achieve fastness in stability, refinement in fastness, and stability in refinement. Only in this way can companies survive and develop in the increasingly competitive pump and valve industry.

The society is an era of information explosion. It is inevitable for companies to encounter competitors in products. There is competition in the industry, which is a good thing for some companies. Because of competition, enterprises have improved the quality of products and services, and consumers have obtained better or more consumption and services with less money. The market is a “screen”. While the industry is developing and progressing, the market is also surviving the fittest enterprises in the industry. Although the current status of the development of the butterfly valve industry is gaining momentum, the national support policies have been greatly improved, and the market demand has continued to increase. Due to the fierce competition in the industry, the pump and valve industry has also made domestic pump and valve related technologies to improve, but many interference factors indicate The development prospects of the pump valve industry are not optimistic.

For some large competitive enterprises, through competition, the scale of the enterprise has become larger and larger, and the popularity has become higher and higher. However, for some small and medium-sized enterprises that are not competitive, they may face the risk of being merged or going bankrupt. In the increasingly fierce valve market, only companies with core competitiveness can gain a foothold in the market, and innovation becomes a weapon for companies to win the market.

Basic knowledge of valve

August 18, 2020

A valve is a device used to control the direction, pressure and flow of fluid in a fluid system. A valve is a device that allows the medium (liquid, gas, powder) in the piping and equipment to flow or stop and can control its flow.

lug type butterfly valve, ductile iron, center lined,

The valve is a control component in the pipeline fluid conveying system. It is used to change the passage section and the flow direction of the medium. It has the functions of diversion, cutoff, throttling, check, diversion or overflow pressure relief. Valves used for fluid control, from the simplest shut-off valves to the various valves used in extremely complex automatic control systems, have a wide range of varieties and specifications. The nominal diameter of the valve ranges from extremely small instrument valves to large diameters of 10m. Valves for industrial pipelines. The valve can be used to control the flow of various types of fluids such as water, steam, oil, gas, mud, various corrosive media, liquid metals, and radioactive fluids. The working pressure of the valve can be from 0.0013MPa to 1000MPa ultra-high pressure and working temperature From the ultra-low temperature of -270℃ to the high temperature of 1430℃. The valve can be controlled by a variety of transmission methods, such as manual, electric, hydraulic, pneumatic, turbine, electromagnetic, electromagnetic hydraulic,

Electro-hydraulic, pneumatic-hydraulic, spur gear, bevel gear drive, etc.; it can act according to predetermined requirements under the action of pressure, temperature or other forms of sensing signals, or simply open or close without relying on sensing signals , The valve relies on the drive or automatic mechanism to make the opening and closing parts move up, down, sliding, swinging or rotating, thereby changing the size of the flow channel area to achieve its control function.

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

Fasteners, fillers and gasket materials of valves

August 17, 2020

There are many other valves parts and 1. Fastener material of valves:

valve bonnets

Fasteners mainly include bolts, studs and nuts. The fastener directly bears the pressure on the valve, which plays an important role in preventing the outflow of the medium. Therefore, the selected material must ensure sufficient strength and impact toughness at the operating temperature. When selecting fastener materials according to medium pressure and temperature, you can choose according to Table 5-1. Name Nominal Pressure Pg (Mpa) Medium Temperature (℃) 300 350 400 425 450 530 Bolt Stud Bolt 1.6-2.5 A3 35 30CrMoA _4.0-10.0 35 35CrMoA 25Cr2MoVA16.0-20.0 30CrMoA 35CrMoA 25Cr2MoVA Nut 1.6-2.5 A3 30 35 _4.0-10.0 30 35 35CrMoA16.0-20.2 35 35CrMoA Table 5-1 must undergo heat treatment when selecting alloy steel materials. When there are special corrosion resistance requirements for tight-return parts, stainless and acid-resistant steels such as Cr17Ni2, 2Cr13, 1Cr18Ni9 can be selected.

2. Filler material of valves:
On the valve, the packing is used to fill the space of the valve cover packing chamber to prevent the medium from leaking through the valve stem and the valve cover packing chamber space.

1. Requirements for packing 1) Good corrosion resistance, the packing must be able to withstand the corrosion of the medium in contact with the medium. 2) The sealing is good, and the packing will not leak under the action of the medium and working temperature. 3) The friction coefficient is small to reduce the friction torque between the valve stem and the packing.

2. Types of fillers Fillers can be divided into two types: soft fillers and hard fillers: 1) Soft fillers: are made of plant materials, namely hemp, flax, cotton, jute, etc., or are made of minerals, that is, asbestos fibers, or Wire ropes braided by asbestos fibers with metal wires inside and graphite powder coated on the outside, as well as pressed shaped fillers, and flexible graphite filler materials newly developed in recent years. Plant-based packing is cheaper, and is often used for low-pressure valves below 100°C; mineral packing can be used for valves with 450-500°C. In recent years, the structure of using rubber O-rings as packing has been gradually promoted, but the temperature of the medium is generally limited to below 60℃. The packing on the high temperature and high pressure valve is also compacted with pure asbestos and flake graphite powder. 2) Hard filler: that is, filler made of metal or metal mixed with asbestos and graphite and filler formed by pressing and sintering of polytetrafluoroethylene. Metal filler is used less.

3. The choice of packing The packing should be selected according to the medium, temperature and pressure. Commonly used materials are as follows: 1) Oil-impregnated asbestos rope, which can be selected according to Table 5-2. 2) Rubber asbestos rope: can be selected according to Table 5-3. 3) Graphite asbestos rope: The asbestos rope is coated with graphite powder. The usable temperature is above 450℃ and the pressure can reach 16Mpa. It is generally suitable for high-pressure steam. Lately, it gradually adopts the compression-shaped packing, which is placed in a single circle and has good sealing performance. 4) Polytetrafluoroethylene: This is a filler that is currently widely used. Especially suitable for corrosive media, but the temperature should not exceed 200℃. It is generally made by pressing or bar stock, and its shape is shown in Figure 5-1. Name, brand, shape and specification (diameter or square side length) Applicable ultimate pressure kgf/cm2 Applicable ultimate temperature (℃) Purpose Oil-impregnated asbestos rope YS450 F 3.4.5.6.8.10 13.16.19.22.25 60 450 For water vapor, air, petroleum Product Y 5.6.8.10.13 16.19.22.25N 3.5.6.8.10.13 16.19.22.25 YS350 F, Y, N 3.5.6.8.10.13 16.19.22.25. 45 350 YS250 F, Y, N 3.5.6.8.10.13. 16.19.22.25 45 250 Table 5-2 Note: The shape code F means square, through the core or one to multi-layer braid; Y means round, with a twisted core in the middle, and one to multi-layer braid on the outside; N means twisted. Name, grade and specification (straight formula or square side length) Applicable ultimate pressure kgf/cm2 Applicable ultimate temperature (℃) Purpose Rubber asbestos packing XS450 3.4.5.6.8 10.13.16.19 22.25.28 60 450 Used for steam and petroleum products XS350 45 350 XS250 45 250 Table 5-3

3. Gasket material:
The gasket is used to fill all the unevenness between the two joint surfaces (such as the sealing surface between the valve body and the valve cover) to prevent the medium from leaking between the joint surfaces. 1. Requirements for gaskets The gasket material has a certain degree of elasticity, plasticity and sufficient strength at working temperature to ensure sealing. At the same time, it must have good corrosion resistance. 2. Types and selection of gasket materials Gaskets can be divided into two types: soft and hard. The soft is generally non-metallic materials, such as cardboard, rubber, asbestos rubber sheet, and polytetrafluoroethylene. Hardness is generally metal material or metal-coated asbestos, metal and asbestos entangled, etc. There are many shapes of gaskets, including flat, round, oval, tooth-shaped, lens-shaped and other special shapes. Metal gaskets are generally made of 08, 10, 20 high-quality carbon steel and 1Cr13, 1Cr18Ni9 stainless steel, which require high machining accuracy and surface finish, and are suitable for high temperature and high pressure valves. Non-metallic gasket materials generally have good plasticity and can be sealed with less pressure. Suitable for low temperature and low pressure valves. The gasket material can be selected according to Table 5-4. Gasket material medium application range Pressure (Mpa) Temperature (℃) Thick cardboard water, oil ≤10 40 Oil-immersed cardboard water, oil ≤10 40 Rubber sheet water, air ≤6 50 Asbestos board steam, gas ≤6 450 poly Tetrafluoroethylene corrosive medium≤25 200 Rubber asbestos board XB-450 Water vapor, air, gas≤60 450XB-350 Water vapor, air, gas≤40 350XB-200 Water vapor, air, gas≤15 200 Oil-resistant rubber asbestos board oil Class 160 3008 steel and XB-450 filling steam 100 45008 steel and XB-350 filling steam 40 3501Cr13, 0Cr13 asbestos filling steam 100 60008 steel and oil-resistant rubber asbestos filling oil 100 350 copper water vapor, air 100 250 aluminum water vapor, air 64 35010 steel, 20 steel water steam, oil 200 4501Cr13 steam 200 5501Cr13Ni9 steam 200 600

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

What is the material of Bolts and nuts of Valve Stem?

August 17, 2020

Bolts and nuts material of valve stem:

bolts and nuts for butterfly valve

The stem nut directly bears the axial force of the stem during the opening and closing of the valve, so it must have a certain strength. At the same time, it and the valve stem are threaded transmission, which requires a small friction coefficient, no rust and avoid seizure.

1. Copper alloy Copper alloy has a small friction coefficient and does not rust. It is one of the commonly used materials. For low pressure valves with Pg<1.6Mpa, ZHMn58-2-2 cast brass can be used. ZQAL9-4 Wuxi bronze can be used for Pg16-6.4Mpa medium pressure valve. For high-pressure valves, ZHAL66-6-3-2 cast brass can be used.

2. Steel When the working conditions do not allow the use of copper alloys, high-quality carbon steels such as 35 and 40 can be selected, and stainless acid-resistant steels such as 2Cr13, 1Cr18Ni9, and Cr17Ni2 can be used. Working conditions are not allowed to refer to the following situations.

1. For electric valves, stem nuts with melon clutches need heat treatment to obtain high hardness or surface hardness.

2. When the working medium or the surrounding environment is not suitable for copper alloy, such as ammonia medium that corrodes copper. When selecting steel stem nuts, pay special attention to thread seizure.

Tianjin Tanghai Valve Manufacturing Co., Ltd. is one of the largest valve bolts and nuts manufacturers in China, main products are butterfly valves, check valves, gate valve and globe valves. Key words: butterfly valve, lug type butterfly valve, wafer type butterfly valve, U-type butterfly valve, double flange butterfly valve, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…)

What is the material of the butterfly valve stem?

August 17, 2020

Stem material classification:
During the opening and closing of the butterfly valve, the valve stem bears the forces of tension, pressure and

buttefly valve stem shaft parts (6)

torsion, and is in direct contact with the medium. At the same time, there is relative frictional movement with the packing. Therefore, the valve stem material must ensure that there is enough at the specified temperature Strength and impact toughness, a certain degree of corrosion resistance and scratch resistance, and good manufacturability. The commonly used stem materials are as follows.

1. When carbon steel is used in water and steam medium with low pressure and medium temperature not exceeding 300℃, A5 ordinary carbon steel is generally used. When used in water and steam medium with medium pressure and medium temperature not exceeding 450℃, 35 high-quality carbon steel is generally used.

2. When alloy steel is used for medium pressure and high pressure, and the medium temperature does not exceed 450 ℃ water, steam, petroleum and other media, 40Cr (chromium steel) is generally used. 38CrMoALA nitriding steel can be used when it is used in water, steam and other media with high pressure and medium temperature not exceeding 540℃. 25Cr2MoVA chromium molybdenum vanadium steel is generally used when used in high pressure steam medium with medium temperature not exceeding 570℃.

3. Stainless acid-resistant steel S is used for non-corrosive and weakly corrosive media with medium and high pressure and medium temperature not exceeding 450℃. 1Cr13, 2Cr13, 3Cr13 chromium stainless steel can be selected. When used in corrosive media, stainless acid-resistant steel such as Cr17Ni2, 1Cr18Ni9Ti, Cr18Ni12Mo2Ti, Cr18Ni12Mo3Ti, and PH15-7Mo precipitation hardening steel can be selected.

4. When heat-resistant steel is used for high-temperature valves whose medium temperature does not exceed 600℃, 4Cr10Si2Mo martensitic heat-resistant steel and 4Cr14Ni14W2Mo austenitic heat-resistant steel can be selected.

Tianjin Tanghai Valve Manufacturing Co., Ltd. is one of the largest valve stem/shaft manufacturers in China, main products are butterfly valves, check valves, gate valve and globe valves. Key words: butterfly valve, lug type butterfly valve, wafer type butterfly valve, U-type butterfly valve, double flange butterfly valve, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…)

What is the material of the main parts of the butterfly valve?-(1)

August 17, 2020

Selection of butterfly valve parts materials:
There are many materials for manufacturing butterfly valves, including ferrous and non-ferrous metals and their

16 U-type-flange-butterfly-vlave-body

alloys of different brands, and various non-metallic materials. The materials for manufacturing valve parts should be selected based on the following factors:

1. Pressure, temperature and characteristics of working medium.

2. The force of the part and its function in the valve structure.

3. It has better manufacturability.

4. If the above conditions are met, there must be a lower cost.

The material of the valve body, bonnet and disc (disc) The body, bonnet and gate (disc) are one of the main parts of the valve, which directly bear the pressure of the medium, and the material used must meet the “pressure and temperature rating of the valve” Provisions.

Commonly used material types for butterfly valves:

1. Gray cast iron: Gray cast iron is suitable for water, steam, air, gas, oil and other media with a nominal pressure of PN≤1.0MPa and a temperature of -10℃~200℃. The commonly used grades of gray cast iron are: HT200, HT250, HT300, HT350.

2. Malleable cast iron: Suitable for water, steam, air and oil media with a nominal pressure

17 center-line-butterfly-valve-plate-disc-parts-4

of PN≤2.5MPa and a temperature of -30~300℃. Commonly used grades are: KTH300-06, KTH330-08, KTH350-10.

3. Ductile iron: suitable for water, steam, air and oil with PN≤4.0MPa and temperature of -30~350℃. Commonly used grades are: QT400-15, QT450-10, QT500-7. In view of the current level of domestic technology, the plants are uneven, and users are often not easy to inspect. According to experience, it is recommended that PN≤2.5MPa, and the valve should be made of steel for safety.

4. Acid-resistant high-silicon ductile iron: suitable for corrosive media with nominal pressure PN≤0.25MPa and temperature below 120℃.

5. Carbon steel: suitable for water, steam, air, hydrogen, ammonia, nitrogen and petroleum products with a nominal pressure of PN≤32.0MPa and a temperature of -30~425℃. Commonly used grades are WC1, WCB, ZG25 and high-quality steel 20, 25, 30 and low-alloy structural steel 16Mn. Six, copper alloy: suitable for water, sea water, oxygen, air, oil and other media with PN ≤ 2.5MPa, and steam media with a temperature of -40 to 250 ℃, commonly used brands are ZGnSn10Zn2 (tin bronze), H62, Hpb59-1 (Brass), QAZ19-2, QA19-4 (aluminum bronze).

18 buttefly-valve-stem-shaft-parts-1

7. High temperature steel: suitable for steam and petroleum products with nominal pressure PN≤17.0MPA and temperature≤570℃. Commonly used grades are ZGCr5Mo, 1Cr5M0. ZG20CrMoV, ZG15Gr1Mo1V, 12CrMoV, WC6, WC9, etc. The specific selection must be in accordance with the valve pressure and temperature specifications. 8. Low temperature steel, suitable for nominal pressure PN≤6.4Mpa, temperature≥—196℃ ethylene, propylene, liquid natural gas, liquid nitrogen and other media, commonly used grades) ZG1Cr18Ni9, 0Cr18Ni9, 1Cr18Ni9Ti, ZG0Cr18Ni9.

9. Stainless acid-resistant steel, suitable for nitric acid, acetic acid and other media with nominal pressure PN≤6.4Mpa and temperature≤200℃. Commonly used grades are ZG0Cr18Ni9Ti, ZG0Cr18Ni10<nitric acid>, ZG0Cr18Ni12Mo2Ti, ZG1Cr18Ni12Mo2Ti<acid and urea>.

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