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Bolted bonnet, swing and lift the valve sealing surface of metal. Connection forms of body and bonnet Class150~Class900 using bolted bonnet; Class1500~Class2500 uses a pressure seal bonnet.
Valve cover gasket forms
Class150~Class300 check valve stainless steel graphite spiral wound gasket; Class600 check valve can be made of stainless steel graphite spiral wound gasket also can uses a metal ring gasket; Class900 check valve can adopt metal ring gasket, Class1500~Class2500 check valve adopts the sealing metal ring.
Valve seat
Check valve seat usually uses the forged steel material, sealing surface of the valve seat can be based on customer requirements of spray welding hard alloy, NPS ≤10''check valve adopts separated type screwed type valve seat, if the user need welding seat structure may also be provided; NPS ≥ 12check valve adopts a welding seat structure; stainless steel check valve valve seat adopts the integral type or in body welding hard alloy after direct machining valve seat. If the user demand, stainless steel check valve can also be used for separating type screwed type and welded seat structure.
Cast steel swing check valve structure characteristics
Large diameter check valve design rings, convenient lifting.
Bolted bonnet, the flange gasket type according to different levels of selection pressure;
CLASS600 check valve can use pressure SelfTight seal structure.
Valve limiter device, to prevent the valve open position is too high and can not be closed.
The solid pin shaft mounting precision, high strength, ensuring the valve performance and life
The rocker has enough strength, turn off when there's enough freedom to facilitate closure of the valve flaps.
Valve flap has sufficient strength and stiffness, valve sealing surface can be based on user requirements of surfacing metal material or embedded nonmetal materials.
Globe valve is closed parts ( valve ) along the center line of the valve seat for mobile. According to this mobile form of flap valve the valve seat through the mouth, change is associated with the valve stroke proportional relationship. As such the valve stem to open or close the trip is relatively short, and has very reliable cutting function, and because the valve seat through the mouth of change and the trip valve proportional relationship, very suitable for flow regulation. Therefore, this type of valve is suitable for cutting or adjusting and throttling. Selection principle is:1, high temperature, high pressure pipeline or equipment should be chosen cut-off valve. A fire power plant, nuclear power plant, petroleum chemical engineering system of high temperature, high pressure pipe. In 2, the pipeline flow resistance the strict requirements of the pipeline. The pressure loss with little place. In 3, a small valve can select needle valve, instrumentation valves, sampling valves, pressure gauge valve. In 4, a flow regulating or pressure regulation, but adjusting accuracy is not high, and the pipeline diameter and relatively small, such as mm nominal diameter≤ 50mm pipeline, appropriate chooses. Synthesis of5, in the industrial production of small chemical fertilizer and chemical fertilizer use nominal pressure PN160nominal pressure 16MPa or PN320nominal pressure 32MPa high pressure angle type stop valve or a pressure angle throttle valves. In 6, the alumina production by Bayer removal of silicon in the workshop, the easy coking line, easy selection of valve body, valve seat can separate place, hard alloy sealing DC type stop valve or a DC type throttle valve. 7, in the construction of city water supply, heating engineering, nominal by smaller pipeline, can choose cut-off, balance valves or piston valve, such as nominal by less than 150mm pipeline. The most obvious advantages are : the opening and closing process, because the valve sealing surface on the body than the friction between the valve is small, and therefore wear. Seat height is typically only open channel diameter of 1/4, so much smaller than the gate. Usually in the valve body and valve has a sealing surface, and thus better manufacturing processes, convenient repair. Nominal pressure and pressure level: PN1.0-16.0MPa, ANSI CLASS150-900, JIS10-20K nominal diameter or diameter: DN10 ～ 500, NPS1/2 ~ 36" connection: flange, welding, threaded and other applicable temperature: -196 ℃ ~ 700 ℃drive mode:, pneumatic, electric, hydraulic, pneumatic and hydraulic linkage, the body material: WCB, ZG1Cr18Ni9Ti, ZG1Cr18Ni12Mo2Ti, CF8(304), CF3(304L ), CF8M (316), CF3M (316L, Ti ). The choice of different materials, are suitable for water, steam, oil, nitric acid, acetic acid, oxidizing medium, urea and other media.
Butterfly valve ( English: butterfly valve ) refers to the closing member ( valve flap or disc for disc ), around the valve axis of rotation to achieve the open and close a valve, in the pipeline mainly as shut off and throttling effect. Butterfly valve opening and closing piece is a disc-shaped butterfly plate, in the valve body around its own axis of rotation, so as to achieve the purpose of opening and closing or regulation. Butterfly valve full-to full-clearance is usually less than 90°, butterfly and butterfly pole itself without self-locking ability, in order to butterfly plate localization, in stem with a worm reducer. The use of worm gear reducer, not only can make the butterfly plate with self-locking ability, make the butterfly plate stop at any position, but also to improve the valve performance. Special butterfly features of industrial high temperature, discharge pressure is higher, the valve nominal diameter, the body uses of carbon steel, valve plate sealing ring adopts a metal ring instead of rubber ring. Large high temperature butterfly valve uses the steel plate welding manufacturing, mainly used for high temperature smoke of air and gas medium pipeline.
In 30, the United States invented butterfly valve,50 time pass into Japan, to 60 time only in Japan used generally, but in China it is 70 time later. The world in general DN300mm above has gradually replaced the gate valve butterfly valve. Compared to a gate valve opening and closing time is short, small operation torque, installation space is small and light weight. In the case of DN1000, the butterfly valve and gate valve of about 2T, about 3.5T, and the butterfly valve is easy and various driving device combination, has good durability and reliability.
Rubber sealing butterfly valve for throttling drawback is that when in use, as improper use will produce cavitation, the rubber seat spalling, damage from happening. To this end, it has developed the international metal sealing butterfly valve, cavitation area decreases, in recent years China has also developed a metal seal butterfly valve, in Japan in recent years has developed cavitation resistance, low vibration, low noise of the comb-shaped butterfly.
General seal seat of life in normal circumstances, the rubber15 years -20 years, metal80 years -90 years. But how to choose the right according to the requirements of working conditions.
Butterfly valve opening and the relationship between the flow rate, basically is linear proportional change. If used to control the flow rate, the flow characteristics and piping flow resistance are closely related, such as the two installation of pipeline valve diameter, form, all the same, and the pipe loss coefficient is different, the flow valves difference will be great.
If the valve is in the larger state of throttle valve plate, the back is easy to damage the valve cavitation occurs, may, generally at 15 °external use.
Butterfly valve in the opening, the valve body and the butterfly plate is formed at the front end of the opening shape to the valve shaft as the center, on both sides of the formation of different state, side of the butterfly plate front along the flow direction and the flow direction, the other side reverse move, therefore, side valve body and the valve plate forms a similar nozzle shape opening, the other side is similar to the orifice the U-shaped opening, side of the nozzle side flow more quickly than the throttle, throttle valve and side below can generate negative pressure, often can appear rubber seal off.
Butterfly valve operating torque, because the opening and the valve opening and closing direction different from its value varies, horizontal butterfly valve, especially for large diameter valve, because the water depth, valve shaft, water head difference generated by the torque can not be ignored. In addition, the valve inlet side device bend, forming a bias current, torque will increase. Valves are at a middle opening, due to hydrodynamic moment function, operation mechanism need self-locking.
