Valve Selection And Examples

The valve is a control component in the fluid delivery system, has many functions such as cut-off, regulation, diversion, prevent backflow, regulator, shunt or overflow relief.

Valves are widely used for fluid control systems, ranging from the simplest sanitary shut-off valves to a variety of valves, used in extremely complex control systems, with a wide variety of specifications. Sanitary valves can be used to control the flow fluids such as air, water, steam, corrosive media, mud, oil, liquid metal and radioactive media. Valves are also divided into cast iron valves, cast steel valves, stainless steel valves, chrome molybdenum steel valves, chrome molybdenum vanadium steel valves, duplex steel valves, plastic valves, non-standard custom valves.
Butterfly Valves
Valve selection steps:
1. According to the pressure of the valve, caliber, the media has been the temperature and the temperature can be selected to adapt to the valve model.
2. Know the way the pipe connection and the caliber of the valve can determine the way the valve is connected.
3. The use of the valve If you know and the conditions of the production process, then you can determine the valve drive device.
4. The general diameter of the valve is the diameter of the pipe, but also according to the pipe diameter to calculate the real use of the valve caliber.
5. To determine the sealing surface of the valve to know what the valve is the medium, temperature and pressure values, the maximum use of the valve body temperature must be greater than the medium temperature.
6. Valve nominal pressure to determine the body according to the material, the media working pressure and temperature.
7. Valve characteristics of the media, working pressure and temperature, you can choose the model and sealing surface.
valve fittings
Valve selection example:
Steam pipe working pressure is 13 kg, the temperature is 350 degrees Celsius, caliber is 100, to choose what kind of valve. From the above known conditions, first determine the material of the valve body, because the steam pressure is 13 kg, the temperature is 350 degrees Celsius, you can choose ductile iron or cast steel. However, from the temperature of 350 degrees Celsius to consider, then the ductile iron is more difficult to choose, so for safety reasons, should use cast steel valves. And then from the pressure to analyze, according to cast steel and long-term pressure temperature, the valve should choose 16 kg or 25 kg is appropriate. Next is the choice of sealing surface, to use stainless steel. And given the valve diameter is 100, diameter is relatively small, so the opening and closing time and torque are not large, then select the manual on it. Generally take the steam pipes are made of seamless steel pipe, and seamless steel pipe are used welding, but in order to make the valve easy to install and repair, it is recommended to use the flange connection.

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Applications and Market Prospects of Stainless Steel Valve

Stainless steel valves are commonly used in chemical applications such as corrosive media, food, pharmaceuticals, oils, liquid metals and radioactive media. The valve ability is relatively limited by many factors.

Sanitary ball valves
Because of its long life, not rust, green and other advantages, stainless steel valves have many industrial applications, so the procurement of stainless steel valves must be required a variety of stainless steel valve production and factory certificate, you can also use the spectrometer for testing, spectrometer due to high precision, is widely used in the precious metals and stainless steel valve detection. The field of application has also been developed rapidly in recent years, some 304,316 L valves are mainly dependent on the equipment testing.

When the valve material such as sanitary ball valve, gate valve, globe valve and check valve are selected according to the nature of the working medium, the influence of the factors such as the concentration, temperature and heat treatment process of the material on the corrosion resistance must be studied at the same time. Good steel is 316L, 904 or titanium valves.

health grade valves
With the petrochemical industry technology and the continuous development of the petrochemical stainless steel valve, the requirements are getting higher and higher, in addition to continue to improve the quality of conventional valves such as J41W stainless steel globe valve, Z41W stainless steel gate valve, especially for corrosive materials Q41F stainless steel ball valves require an increasing amount, some PTA plants, polyester plants and polyester spinning units for chemical fiber production, to strive to develop corrosion-resistant technology, 316L stainless steel sanitary valves are featured with corrosion-resistant, high strength, light, long life and other excellent features.
The society progress of the industry is increasing, the use of stainless steel valve products industry is also increasing, new industries and new products will also slowly replace the cast iron valves, which for the stainless steel valve industry to bring new opportunities for market development prospects.

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The Development Prospect of High Pressure Valve Industry

The Development Prospect of High Pressure Valve Industry
In China’s current valve market, in addition to low-pressure valve to the international market to accept the level, the high-pressure valve still need to rely on imports. In the macroeconomic continued to be optimistic about the situation, the valve industry, most of the production and sales indicators have maintained a rapid growth, but by the price war, the industry sales revenue and profits fell sharply over the same period last year. With the world economy pick up, China’s import and export of valve products has also increased, but because of high-end technology still have a large gap with foreign manufacturers, compared to the next period of time, product technology will become a control of China’s valve product development bottleneck.

From the product situation, China’s valve industry has been able to produce a dozen categories of products, such as gate valve, globe valve, sanitary ball valve, butterfly valve, safety valve, sanitary check valve, throttle valve, plug valve, Traps, emergency shut-off valve, the maximum temperature is 570 ℃, the lowest is -196 ℃, the maximum pressure is 600MPa, the maximum diameter is 5350 mm. In addition, according to the relevant departments statistics, China’s annual valve market turnover is up to 50 billion yuan, of which more than 100 billion market is occupied by foreign valve enterprises. The sanitary valves are indispensable fluid control equipment for various sectors of the national economy such as oil, chemical industry, power station, long-distance pipeline, shipbuilding, nuclear industry, various low-temperature engineering, aerospace and marine oil production. After years of development, the number of valves in China ranks first in the world, the size of the valve business is about 6,000, of which the annual output value is more than 500 million.

food industry
At present, there are still some problems in China’s valve industry, such as China’s valve enterprises mainly are low-level, small-scale, family-based enterprises. In the product, due to repeated investment, the introduction of technology is not enough, China’s leading enterprises in the valve products is still low-quality mass products. At present, various valves are generally exposed, leakage, the appearance of the quality is not high, short life, the operation is not flexible and the valve electric devices and pneumatic devices are not reliable and other shortcomings, some products are equal to the international level, some high temperature and pressure and key devices on the need for valves still rely on imports.

The industrial structure, the valve industry, industrial chain, as well as the degree of specialization of the industry and foreign enterprises there is a large gap between the domestic valve product quality is low because the rapid expansion of the market, the original state-owned enterprises have Shut down and turn, although a number of township enterprises to develop rapidly, but because of the low starting point of township enterprises, technical strength is very weak, poor equipment, most of the products are imitated production, especially for the low pressure valve for drainage problems Does not affect the future prospects of China’s valve industry. This is mainly due to the support of national policy and the strong demand of the valve products market, especially in several century project “West-East”, “West to East”, “South-North Water Diversion” and other projects need a large number of valve products.

food

In addition, China is facing the arrival of the industrial era, the petrochemical industry, power industry, metallurgical industry, chemical industry and urban construction, such as the use of large valves will enhance the demand for valve products. For example, the power industry, “Eleventh Five-Year” period in the coal-fired units large and medium-sized projects required to predict the total valve: the total demand for valves 153,000 tons, the average annual demand is 30,600 tons; total demand of valve is 3.96 billion yuan. The average annual demand is $ 792 million. In addition, China is gradually becoming the world’s largest processing plant, the valve products processing production is facing greater development space, as long as companies can seize the opportunity to strengthen research and development capabilities, and continuously improve product technology content and product quality.

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Six Solutions to The Leakage of Control Valves

Six solutions to the leakage of the control valve
1) Increasing the sealing grease method
For valves that do not use sealed grease, can increase the sealing grease to improve stem seal performance.

2) Increasing the packing method
In order to improve the sealing performance of the packing on the stem, a method of increasing the packing may be used. Usually using double-layer, multi-layer mixed filler form, simply increase the number, such as 3 to 5, the effect is not obvious.

valve fittings

3) Replace the graphite packing method
Large use of PTFE filler, because of its operating temperature is in the range of -20 ~ +200, when the temperature is in the upper and lower limits, changes in the larger, the seal will be significantly reduced, aging fast, short life. Flexible graphite fillers can overcome these shortcomings and long service life. So some of the factory all the PTFE filler to graphite filler, and even the newly purchased control valve will be one of the PTFE filler into graphite filler after use. But the use of graphite filler hysteresis, and some also have a crawling phenomenon, which must be considered.

Divert Valves

4) Changing the flow direction, set P2 in the stem end method
When the △ P is large, P1 is large, the seal P1 is clearly more difficult than the seal P2.Therefore, can be taken to change the flow direction, P1 in the stem end to P2 at the stem end, which is high pressure, Large sanitary check valves are more effective, such as bellows valves that should normally be considered for sealing P2.

5) Using lens pad sealing method
For the seal of the upper and lower covers, the valve seat and the upper and lower valve body seal. If the plane seal, under high temperature and high pressure, poor sealing, causing leakage, you can use the lens pad seal, can get satisfactory results.

6) Replacing the gasket
So far, most of the gasket is still using asbestos board, at high temperatures, poor sealing performance, life is short, causing leakage. In this case, you can use the winding gasket, “O” ring, now many plants have been used sanitary valves.

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What are the features and advantages of high temperature valves

What are the performance and advantages of high temperature valves?
The performance of the high temperature valve is as follows:
1. High temperature valve quenching is good, can be deep quenching, rather than the surface of the anti-saw-lock surface hardening
2. Less brittleness of tempering
3. High temperature valve processing is good, after processing, it is beautiful
4. Good weldability
5. The impact and performance of the absorption is good, the hammer hit up with a sense of bounce, can not be violent and damage.

Sanitary-Sampling-Valves-161114

The advantages of high temperature valves:
(1). Good workability
(2). Impact absorption performance is good
(3). Welding easy
Element symbol: Cr-Mo

valves

A type of high temperature valves
Stainless steel ball valve belongs to a kind of sanitary valves, according to the distinction and selection of the sphere, some ball system can be operated easily, the line for publicity can open and close conveniently.

Sanitary-Elbows-161207

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The Difference of Pneumatic and Hydraulic Sanitary Valves

The difference of Pneumatic and hydraulic sanitary valves in the drive
Pneumatic and hydraulic sanitary valves were operated by a certain pressure of air, water, power, used cylinder and piston movement to drive the health-class valves, the general pneumatic air pressure is less than 0.8MPa, hydraulic or hydraulic pressure is between 2.5 MPa and 25 MPa.

ball valves

It can be used to drive the sanitary check valves, sanitary diaphragm valve; rotary gas and liquid ball valves, plug valves or butterfly valves and other valves. The driving force of the hydraulic device is large, and it is suitable for driving large diameter valves.
Sanitary Butterfly Valves
If used to drive the plug valve, ball valve and butterfly valve, you must use the reciprocating motion of the piston to change the surface rotary motion. In addition to the use of cylinder or cylinder piston to drive, there are pneumatic film driven, because its travel and driving force is small, it is mainly used to adjust the sanitary valves.

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