1. Before valve installation, you should carefully check the model used by the valve, and design specifications are consistent;
2, depending on the model and the factory manual check valve controls whether the valve under the conditions required by the application;
3, when the valve lifting, rope should be tied in body and bonnet flange connections, do not place tied to the wheel or the valve stem, so as not to damage the stem and hand wheel;
4, the installation of valves in horizontal pipelines, the stem should be straight up, do not allow the stem down installation;
5. When installing the valve, shall not be used to force connection Shenglayingzhuai counterpart, so as to avoid uneven force, causing damage;
6, stem gate valve should not be mounted in the ground damp place to avoid stem rust.
Supporting electric actuators
Electric actuators and valves more support, used in automatic control systems. Many types of electric actuators in action in different ways, such as rotary electric actuator output torque angle, and straight stroke electric actuator output thrust displacement. Actuators are applied when the type of system should be selected on the basis of the valve needs to work.
A flange connection:
This is the most frequently used valve connection form. Press the combination of surface shape can be divided into the following categories:
1, smooth style: not for high pressure valves. Processing more convenient
2, lenticular: higher working pressure, can be used in hard-washer
3, tenon slot: Available plastic deformation larger washers use in corrosive media is more extensive and better seal.
4, trapezoidal trough: oval metal ring gasket for use in the working pressure ≥64 kg / cm of valves, or high temperature valves.
5, lens type: washer lens shape, made of metal. For operating pressure ≥100 kg / cm high pressure valves, or high temperature valves.
6, O-ring type: This is a relatively new form of flange connection, it is with the emergence of a variety of rubber O-ring, and developed it in a sealed-efficient form of connection.
Second, the clip connection:
Directly through the valve and pipe connection in the form of two clamped together with bolts.
Third, the welded connections:
Direct and pipe welding
Fourth, the threaded connection:
This is a simple connection method, commonly used in small valve. And two cases:
1, direct sealing: external thread directly from the seal. To ensure that the connection does not leak, often with the lead oil, hemp and Teflon tape filling; wherein Teflon tape, has become increasingly widespread use; good corrosion resistance of this material, the sealing effect pole good, easy to use and preservation, demolition, you can completely remove it, because it is a layer of non-tacky film, hemp oil is much more superior than the lead line.
2. Indirect sealing: thread tighten force transmitted to the gasket between two planes, so that the gasket for sealing purposes.
Fifth, the ferrule connection:
Ferrule connection, its connection and sealing principle is that when tightening the nut, ferrule under pressure, so that the blade portion bite into the outer tube, the outer cone sleeve and the joint body under pressure cone seal, thus possible to reliably prevent leakage.
This connection type advantages are:
1, small size, light weight, simple structure, easy disassembly;
2. Connect power, using a wide range, can withstand high pressure (1000 kg / cm), high temperature (650 ℃), and shock and vibration
3, you can use a variety of materials for corrosion;
4, machining accuracy is not required; easy to install high altitude.
Ferrule connection type, has been used in China some small-caliber valve products.
Sixth, clamp connection:
This is a fast connection method, it takes only two bolts for frequent removal and low pressure valves.
Seven, in the self-tightening connection:
All of the above connection form, is the use of force to offset the media pressure to achieve seal. Here the use of media pressure from the tight connection form. Its inner cone ring is mounted at the opposite side with medium angled medium pressure to the inner cone, and passed to the ring, in a certain angle of the cone, resulting in two components, a Body axis parallel outward, the other pressed against the body wall. This latter component is self-tightening force. Greater media pressure, self-tightening force is also greater. Therefore, this connection type, suitable for high pressure valves. Than the flange connection, to save a lot of material and labor, but also requires a certain preload to the pressure in the valve is not high, use and reliable. Made use of the principle of self-tight seal valves, usually high-pressure valve.
Valve connections are still many forms, such as the need to remove some small valves, with tubes welded together; some non-metal valves, a plug-type connection, and so on. Valve according to specific user to a specific treatment break situation.
There are valves and fittings, which are used in connection or control system piping. Valves and fittings can not exist independently, complement each other. Valve tube of carbon steel and stainless steel, as well as PVC, or other commonly used is the first two materials in recent years, as people’s living standards improve, requirements for foodstuffs consequent demand up. It led to the rapid development of food machinery, so stainless steel sanitary valve fittings production industry will be prosperous together, people often say valves, fittings, multi-use or stainless steel sanitary level.
Before production and post-production professional valve maintenance work prior to welding, the valve service in manufacturing operations plays a vital role in the proper and orderly and effective maintenance will protect the valve, the valve function normally and extend valve use life. Valve maintenance work may seem simple, it is not. Work often neglected aspect.
First, the valve greasing, the grease quantity is often overlooked issue. After the grease gun refueling, after the operator selects valves and coupling greasing the way, were greasing operations. There are two cases: one less injection insufficient greasing grease, sealing surface due to lack of lubricant accelerate wear. On the other hand greasing excessive wastage. That there is no category based on the valve type, different valve sealing capacity for precise calculations. Can be calculated from the sealing valve size and type of capacity, and then inject the right amount of grease reasonable.
Second, the valve greasing, often ignored pressure problems. In greasing operation, grease pressure regularly showed peak changes. Pressure is too low, seal leakage or failure, the pressure is too high, greasing port plug, sealed lipid hardening or seal with the valve ball, valve plate locking. Typically grease pressure is too low, the injection of much grease into the bottom of the valve chamber, generally occurs in a small gate. The grease pressure is too high, on the one hand greasing nozzle check, and if so fat replacement hole blocked ascertain the situation; on the other hand is a lipid hardening, to use cleaning fluid, repeated failure of the sealant to soften and inject new grease replacement . In addition, the seal type and sealing materials, but also affect the grease pressure, different sealing forms have different greasing pressure, in general, hard seal grease pressure than a soft seal.
Third, valve greasing, note the switch position of the valve in question. When valve maintenance is generally in the open position mode, select Close maintenance under special circumstances. Other valves in the open position can not always be punished. When the valve is in the closed state of conservation must ensure that grease along the full seal ring groove, if the open position, the sealing grease directly fall into the flow channel or valve chamber, resulting in waste.
Fourth, the valve greasing, often ignored greasing effect problems. Grease operating pressure, greasing, switch bits are normal. However, to ensure that the valve greasing effect, and sometimes need to open or close the valve, for lubrication check to make sure the valve ball or gate surface lubricity evenly.
Fifth, grease, pay attention to body drain plugs and relief issues. After the pressure test valve, sealing chamber valve chamber gas and water due to environmental temperature and boost, to conduct sewage relief greasing, to facilitate the smooth progress of grease injection work. After greasing air and water seal chamber is sufficient to displace. Timely vent valve cavity pressure off, but also to protect the use of safety valve. After greasing, be sure to tighten emissions and pressure relief plugs to prevent accidents.
Sixth, grease, pay attention to the problem of fat evenly. Normal greasing from greasing port nearest the fat out of fat hole first, then to the lows of the last high point, successive out fat. If you do not follow the law or no fat, prove the existence of congestion, timely and clear the pass processing.
Seventh, we must observe the valve size and seat ring flush problem greasing. Such as ball, if there is interference open position can be adjusted to the stopper in the open position, confirm the path straight locks. Adjust the limit not only the pursuit of one open or closed position, be considered as a whole. If the open position flush off is not in place, it will cause the valve closed lax. Similarly, adjust the clearance in place, but also consider open position accordingly. Ensure that the valve is at right angles to the trip.
Eighth, after greasing, some sealed grease port. Avoid impurities entering, or greasing mouth lipid oxidation, capping to apply anti-rust grease to avoid rusting. To apply when the next operation.
Ninth, grease, it should also consider in the future delivery of oil in order deal with specific issues. In view of the different qualities of diesel and gasoline, should consider erosion and decomposition gasoline. After the valve operation when encountered gas segment operations, replenish grease to prevent wear from happening.
Tenth, grease, do not ignore the stem portion of the grease. Sliding sleeve valve shaft portion or filler, but also the need to maintain lubrication to reduce friction during operation, if they can not ensure the torque increase lubrication and wear parts, the electric operation, switch laborious manual operation.
Eleventh, some marked with an arrow on the valve body, if not accompanied by an English FIOW writing, for the direction of sealing seat role, not as a medium flow reference, vent valve from the opposite direction. Typically, two-seater with two-way flow valve seal.
XII, valve maintenance, but also pay attention to the head and electric drive mechanism in water issues. Especially in the rainy season, rainwater infiltration. First, make the drive mechanism or drive shaft sleeve rust, two winter freeze. When electric valve operating torque caused excessive damage to transmission parts cause the motor torque load or protection tripped over electric operation can not be achieved. The drive member is damaged, the manual operation can not be performed. After the super torque protection action, manual operation is also unable to switch, such as the forced operation and will damage the internal metal parts.
But small friction torque, hysteresis small.
Why desalination water medium using rubber lined butterfly valve, fluorine diaphragm short life?
Desalination of water medium containing low concentrations of acid or base, they have more corrosive to rubber. Rubber corrosion performance expansion, aging, low intensity, with rubber lined butterfly valve, diaphragm use effects are worse in essence, rubber impatient due to corrosion. After the rubber lined diaphragm valve to improve the corrosion resistance of good lined diaphragm valves, but lined diaphragm membrane then stand up and down the collapse were broken off, resulting in mechanical damage, shorter valve life. Now the best way to deal with specific water valve, it can use to 5 to 8 years.
Why shut-off valve should try to use
In summary, the valve maintenance truly scientific attitude, to achieve the purpose of the valve maintenance and application of the desired effect.
Valve applications FAQ
Why the double valve seal valve can not be used as a cut off valve?
Advantages seat valve spool force balance the structure, allowing the pressure large, and it highlights the shortcomings of the two can not both be a good contact with the sealing surface, causing a large leak. If it artificially, mandatory for cutting off occasion, obviously not good, even if it made a lot of improvements (such as double-sealed sleeve valve), is also undesirable.
Why easy oscillation valve seat valve small opening?
For single-core, when the medium is the flow of open type valve stability; when the medium is the flow of closed type, the stability of the valve difference. There are two spool valve seat under the spool in the flow closed, the valve is open flow, so that when the small opening, the flow of closed type valve spool is easy to cause vibration, which is the seat valve The reason can not be used where the small opening.
What straight trip regulating valve attempts to prevent poor performance, rotary valve attempts to prevent the performance?
Straight trip throttle valve spool is vertical, while the medium is the level of flow into the outflow valve cavity flow must turn back street, so that the valve flow path becomes quite complex (shaped like inverted S-type). Thus, there are many dead, as the medium of precipitation provides a space for the long run, causing blockage. Direction of the rotary valve throttling is the horizontal direction, medium level of flow into the level of outflow, easy to medium is not clean away, while the flow path is simple, the media space and few precipitation, it attempts to prevent the rotary valve performance.
Why cut off the pressure rotary type valve large?
Large rotary type valve to cut off the pressure, because the resultant media in the spool or the valve on a board on the shaft torque produced is very small, so it can withstand greater pressure.
Why straight stroke adjustment valve stem smaller?
It involves a simple mechanical principle: sliding friction, rolling friction small. Linear actuator valve stem up and down movement, the packing slightly compressed that it will stem a very tight package, have a greater backlash. To this end, stem design very small, another commonly used filler of PTFE packing friction coefficient in order to reduce backlash, but the resulting problem is to send small stem, is easily bent, packing too short life. Solve this problem, the best way is to turn valve stem with a tour, that the control valve rotary type, which stem two to three times thicker than the straight stem stroke, and use long life of the graphite packing, stem stiffness Good, filling long life, hard seal?
Shut-off valve required leakage the lower the better, soft sealing valve leakage is the lowest cut off the effect is good, but not wear, poor reliability. From leakage and small, sealed and reliable double standards, as hard soft sealing off sealing off well. Such as full-function ultra-light control valve, sealing the reactor with wear-resistant alloy protection, high reliability, leakage rate of 10 to 7, it has been able to meet the requirements of shut-off valve.
Routine valve maintenance
1, the valve should be kept dry and ventilated room, to be blocked at both ends of the path.
2, long-term storage of the valve should be checked regularly to remove dirt and surface coated with anti-rust oil processing.
3, after installation, should be regularly inspected, the main test items:
(1) sealing surface wear.
(2) the stem and stem nut trapezoidal thread wear.
(3) a filler is antiquated, if damaged should be replaced.
(4) after valve repair assembly, sealing performance test should be carried out.
The operation of the valve, all kinds of valves should be complete and intact. Bolt flange and bracket indispensable, threads shall intact, does not allow any loosening. Hand tighten the nut on the wheel, if found loose should be tightened, so as not to wear hand wheel or lost connections and nameplate. Handwheel if lost, not allowed to use wrenches to replace, should be fully serviced. Gland does not allow skew or no pretension clearance. Susceptible to rain, snow, dust, sand and dirt contaminated environment valve, the valve stem to install a protective cover. Valves on the scale should be kept intact, accurate and clear. Valve seals, caps, pneumatic accessories, etc. should be complete and intact. Insulation jacket should be no dents, cracks.
Do not allow the operation of valves beat, stand or supporting weight; especially non-metallic valve and cast iron valve, but also to prohibit.
China’s valve manufacturing industry after decades of development, has made great progress, to achieve a significant increase in valve production.
China’s valve manufacturing industry in the huge demand environment, will present a better development prospects.
Situation technical level
The aftermath of the financial crisis in the world economy is gradually restored, as China’s import and export of electromechanical products market valve is gradually steady growth, the level of international competition in the valve industry will be more intense. China’s valve manufacturers and foreign manufacturers of relatively large valve, there is a big gap between our main high technology aspects. Product innovation and upgrading has become a major stumbling block to block China’s rapid development of valve products.
Valve is an important industrial fluid control equipment, involving many sectors of the national economy, is an important foundation for the development of the national economy equipment. After decades of development, China’s valve products have been formed more than a dozen categories, especially the ranking in the world in the number of enterprises and production and sales of both, but mostly small-scale, low-level valve business, the products are low-end as the Lord.
Since the reform and opening up, the rapid expansion valve market, state-owned enterprises by the institutional impact of the crisis suffered Guantingbingzhuan, township and private enterprises because of the limited technology, only to imitate the production, which is caused mainly due to lower domestic valve quality. Countries have introduced policies to revitalize the equipment manufacturing industry, in particular, focus on supporting the development of common manufacturing base. Our country is facing the transition from the agricultural age to the industrial age, will significantly increase the demand for industrial valve products. Support and huge market demand for products of the national policy will be a powerful driving force of the rapid development of the valve industry.
Market analysts believe that the development trend of the valve, will be the main topic for quite some time the market. Future pattern will tend to develop the following aspects of application development.
First, the good performance of the development of hydraulic control valves, such as emissions from large, high sensitivity, corrosion, abrasion, zero leakage of the hydraulic control valve, the development of integration technology, computer technology, high-level monitoring technology hydraulic control valve, development Feasibility work is good, safe, comfortable and good products.
Second, the development of high-performance large-scale control valve to suit the need of our major projects, the development of micro-valves, to meet the needs ditch dig trenches, buried cables and other narrow job to adapt to the development of power plants, petroleum, coal, water conservancy, farmland, urban construction and the various needs of new varieties of valve; the development of a variety of conditions regulating valve can monitor, control and improve operator working conditions of intelligent electric valve. Promising products are: medium-sized intelligent electric control valve, miniature intelligent electric control valve, remote intelligent electric valve.
In addition, the development of high-security, high feasibility and performance of a good high-level products, development of valve equipped with advanced electronic technology integration of large valves, deformation of the product to develop universal, standardized, serialized direction.
Experts point out that the application of agricultural production in all kinds of agricultural films, film, agricultural water-saving equipment such as valves pipeline valves wide application in modern agriculture, rural applications are increasing pipeline valves, only to solve the drinking water project chin pipe valves demand is considerable. Demand in various valves pipelines urban architecture also greatly increased. Automotive industry using valve manufacturing automotive components increased, the developed countries have an average power plant valves more than 10 billion, with an average usage of 7.0 billion power plant valves. These are spurring demand valve industry.
China valve manufacturing industry has been able to provide about a dozen categories, more than 3000 models, more than 4,000 specifications of the product for the user department, its performance parameters ranging from vacuum valve to 1000Mpa EHV valve, cryogenic temperatures from -196 ° C to high temperature 570 degrees Celsius. China Valve’s main products have been basically able to meet the needs of the domestic market, the market sets the rate of the valve, and complete sets of levels have greatly improved the ability of domestic valves already have some of the revitalization of the foundation.
However, China’s valve industry, small and medium enterprises are still the main valve manufacturing industry in China under huge demand environment, we will present a better development prospects.
January to November 2007, China and cock valve manufacturing industry realized a total industrial output value of 84,288,398 yuan, an increase of 31.47% over the previous year; to achieve total sales revenue 80,571,055 yuan, an increase over the previous year 29.36%; achieve cumulative total profit of 5,772,097 yuan, over the previous year an increase of 44.16%. 2008 January to August, China and cock valve manufacturing industry realized a total industrial output value of 73,321,603,000 yuan, an increase of 27.02% over the previous year; to achieve total sales revenue of 70,451,147,000 yuan, an increase of 27.27% over the previous year; to achieve total total profit 4,470,009,000 yuan, an increase of 15.37 percent over the same period last year. “Five” and the coming years, China petrochemical, natural gas, metallurgy, electricity, urban construction and other industries have a lot of demand for valves, “Eleventh Five-Year” period, China’s total demand will reach 345 valve billion, therefore, the valve industry has a huge market space for development.
China’s valve production technology has made some achievements, but China’s valve industry due to restrictions by the level of the casting process, cast steel, cast iron and other raw materials in the production process wastes a lot. Faced with increasingly fierce competition in the market and increasingly tight valve resources market, casting session in a lot of waste, is not conducive to China’s valve industry cost savings, is not conducive to China’s valve industry in the fierce fight for greater competition in the market of living space, but not conducive to long-term development of the valve industry.
In order to reduce production costs, for the valve industry make more production space, for long-term healthy development of the valve industry, China’s valve industry must avoid casting process waste materials. This aspect can save by raising awareness of foundry workers to achieve; on the other hand, it requires companies to increase research efforts to develop new casting process or the introduction of new casting equipment, in order to better prevent waste caused by the casting process , to reduce production costs and improve the quality of the valve
Valve size and type, shall meet the requirements of piping design documents.
1, the valve type should be specified in accordance with national standard code requirements. If the enterprise standards, should be specified instructions model.
2, valve job pressure ≥ pipeline working pressure, without affecting the price of the premise, the valve can withstand working pressure should be greater than the actual pipeline working pressure.
3, the valve manufacturing standards, should explain the basis of the national standard code, if the file should be attached to business enterprise standards, procurement contract.
Valve performance testing:
1, the valve of a standard high-volume manufacturing, should be entrusted to an authoritative organization for testing the following properties: ① valve pressure in the working conditions for opening and closing torque; ② valve testing resistance coefficient of water in the pipeline condition.
2, the valve should be carried out in the factory following detection: ① valve in the open position, the valve shall withstand the internal pressure detected value twice the working pressure valve; ② valve in the closed position, the sides are to withstand 11 times the working pressure valve value, no leakage; but the metal sealing butterfly valve, leakage is no greater than the relevant requirements.