原文：
            随着工业技术的飞跃发展，对阀门行业提出了更加严格的要求，尤其是蝶阀在低温介质中的使用，除了能满足常温状态下一般阀门所具有的性能之外，更重要的是在低温状态下阀门密封的可靠性，动作的灵活性以及对低温阀门的一些其它特殊要求。 因为蝶阀具有结构紧凑、体积小、重量轻(与相同压力，相同通径的闸阀相比可减轻40%～50%)流体阻力小、启闭迅速等一系列优点，因此得到广泛的使用。但我国在一些低温装置，如天燃液化设备、空气分离设备以及变压吸附设备等化工行业所采用的阀门有80%以上还是截止阀或闸阀，采用蝶阀的数量很少。其主要原因是旋塞阀金属密封蝶阀在低温状况下密封性能表现不良，以及其它一些因结构不合理等原因造成介质内漏和外漏的现象，严重的影响这些低温设备的安全和正常运行，不能满足低温设备的要求。 根据我国低温装置的不断发展，对低温阀门的要求日益增大，因此对金属密封蝶阀进行结构上的改进，开发了三偏心纯金属高密封性能的蝶阀，这种蝶阀无论介质是高温还是低温均能满足其需要。现结合其结构特点，仅对低温性能方面作简单介绍。

         一、对低温碟阀密封性能的要求： 低温阀门产生泄漏的原因主要有两种情况，一是内漏；二是外漏。

1)阀门产生内漏主要原因是密封副在低温状态下产生变形所致。当介质温度下降到使材料产生相变时造成体积变化，使排泥阀原本研磨精度很高的密封面产生翘曲变形而造成低温密封不良。我们曾对DN250阀门进行低温试验，介质为液氮(-196℃)蝶板材料为1Cr18Ni9Ti(没经过低温处理)发现密封面翘曲变形量达0.12mm左右，这是造成内漏的主要原因。 新研制的蝶阀由平面密封改为锥面密封。阀座是一个斜圆锥椭圆密封面，与嵌装在蝶板上的正圆形弹性密封环组成密封副。密封环可在蝶板槽内径向浮动。当阀门关闭时，弹性密封环首先和椭圆密封面的短轴接触，随着柱塞阀阀杆的转动逐渐将密封环向内推，迫使弹性环再和斜圆锥面的长轴接触，最终导致弹性密封环与椭圆密封面全部接触。它的密封是依靠弹性环产生变形而达到的。因此当阀体或蝶板在低温下产生变形时，都会被弹性密封环来吸收补偿，不会产生泄漏和卡死现象。当阀门打开时这一弹性变形立即消失，在启闭过程中基本没有相对磨擦，故使用寿命长。

 2)阀门的外漏：其一是阀门与管路采用法兰连接方式时，由于连接垫料、连接螺栓、以及连接件在低温下材料之间收缩不同步产生松弛而导至泄漏。因此我们把阀体与管路的连接方式由法兰连接改为焊接结构，避免了低温泄漏。其二是阀杆与填料处的泄漏。一般多数阀门的填料采用F4，因为它的自滑性能好、止回阀摩擦系数小(对钢的摩擦系数f=0.05～0.1)，又具有独特的化学稳定性，因此得到广泛应用。但F4也有不足之处，一是冷流倾向大；二是线膨胀系数大，在低温下产生冷缩导致渗漏，造成阀杆处大量结冰，至使阀门开启失灵。为此研制的低温蝶阀采用自缩密封结构即利用F4膨胀系数大的特点，通过予留的间隙达到常温、低温都可以密封的目的。

       二、阀体、阀杆轴衬的设计要求：

 1)低温阀门壳体结构形状。材料选择的正确与否对阀门的正常可靠工作有着极其重要的意义。蝶阀的结构特点与截止阀、闸阀相比，不但避免了因形状不规则，壳体壁厚不均匀，在低温下产生的冷缩，温差应力所引起的变形，而且由于蝶阀体积小，阀体形状左右基本是的称的，因而热容量小；予冷量消耗也小；形状规则又便于对阀门的保冷措施。如新研制的DD363H型碟阀为保证阀门在低温下的可靠使用，完全按照低温阀的特殊性进行设计和制造，如：壳体材料选择了具有立方晶格的1Cr18Ni9Ti奥氏体不锈钢等。

 2)阀杆衬套的选择：根据用户反映，氧气专用阀有些低温阀门在运行当中，阀门的转动部位发生粘滞，咬合现象时有发生，主要原因是：配对材料选择不合理，予留冷间隙过小，以及加工精度等原因所致。在研制低温阀门时，采取了一系列措施，防止出现以上现象。例如：我们对阀杆上、下轴衬选用了具有摩擦系数小及自润滑性能的SF-1型复合轴承，这样可以适用于低温阀门的一些特殊需要。 金属密封型蝶阀具有的特点是一些普通阀门所不具备的。尤其是流阻小、密封可靠、启闭迅速、使用寿命长等。本公司研制的三偏心金属密封蝶阀的密封力来自弹性环的变形达到密封，因而不需要借助介质作用力，故可做双向密封用。根据蝶阀的一些特点将会被更多的人所重视。今后也会有更多的蝶阀应用到低温设备中。

“ Low-temperature device application on the metal seal butterfly valve ”是由中国蝶阀网提供的阀门新闻，译文仅供参考。另外，中国蝶阀网还提供相关产品搜索： 衬胶蝶阀 、 金属密封（硬密封）蝶阀、 通风蝶阀 、 陶瓷蝶阀 、 更多蝶阀产品、 蝶阀价格 等。

译文：
            With the rapid development of industrial technology, on the valve industry made more stringent requirements, in particular valve used in low-temperature medium, in addition to meet the normal condition, with the general performance of the valve, the more important In the low temperature valve seal reliability, flexibility of movement as well as some other special low-temperature valve requirements. Because the valve has a compact structure, small size, light weight (with the same pressure, compared with the same diameter of the valve can reduce 40% ~ 50%), fluid resistance small, open and close rapidly and a series of advantages, it is widely used . But our country in a number of low-temperature devices, such as days of fuel liquefaction plants, air separation equipment, and pressure swing adsorption equipment,Bellows Seal Valves valves used in chemical industry, 80% above or cut-off valve or gate valve, butterfly valve using a small number. The main reason is the metal seal butterfly valve in the low temperature sealing performance under adverse conditions, as well as other causes for irrational structure of leakage and leakage within the media phenomenon, serious effects of low temperature devices safe and normal operation, can not meet cryogenic equipment. According to the continuous development of China's low-temperature device, the valve on the low temperature requirements of growing, so metal sealing butterfly valve for structural improvements, development of pure metal three eccentric high sealing performance butterfly Butterfly Valvesvalve, butterfly valve, whether this medium is high or low temperature can meet their needs. Is combined with its structural features, only for a brief low-temperature performance. One of the low temperature sealing performance butterfly valve requirements: Low-temperature valve and leakage are two main causes of the situation, one internal leakage; second is leakage. 1) mainly due to leakage within the valve and seal pair at low temperature due to deformation. When the medium temperature dropped to produce the material volume change caused by phase transformation, so that the original seal with high precision surface grinding produces warpage caused by low-temperature seal bad. We had a low-temperature test valves DN250, medium is liquid nitrogen (-196 ℃) disc material 1Cr18Ni9Ti (not after low temperature treatment) found that warpage of the sealing surface reached about 0.12mm, which is the main reason resulting in leakage . The newly developed valve seal from the plane to cone seal. Is an oblique elliptical cone seat sealing surface, and embedded board is mounted butterfly round flexible seal ring seal composed of Vice. Seal ring groove in the disc radial float. When the valve is closed, the first elastic sealing ring and sealing surface of the short axis of elliptical contact with the rotating valve stem seal ring gradually pushing inward to force the flexible ring again and the long axis oblique cone surface contacts, resulting elastic sealing oval ring sealing surface with all the contacts. It relies on elastic sealing ring deformation and to achieve. So when the valve body or disc in the low temperature deformation, the sealing ring will be flexible to absorb the compensation, will not produce the Check Valvesphenomenon of leakage and card dead. When the valve opens immediately disappear when the elastic deformation, in the opening and closing the process is relatively little friction, so long life. 2) leakage of the valve: one is the use of valves and pipe flange connection, because connections litter, connecting bolts, and connections between the materials at low temperatures generated relaxation and contraction are not synchronized lead to leakage. So we put body and pipeline connection to the flange welded structure, avoid low-temperature leakage. The second is the leakage of stem and padding. For most of the filler valve with F4, because of its good performance from the sliding friction coefficient (the friction coefficient of steel f = 0.05 ~ 0.1), but also has unique chemical stability, so widely used. However, there are shortcomings F4, one cold dip large; Second, linear expansion coefficient, produce shrink at low temperatures lead to leakage, resulting in a large number of frozen stem Department to open the valve failure. Used for this developed by low-temperature valve seal structure from reduced use of F4 expansion coefficient that is characteristic of the gap left by up to room temperature, low temperature can be sealed purposes. 2, valve, valve stem bushing design requirements: 1) The low temperature structure of the shape of the valve housing. The correct choice of materials or reliability of the normal valve has an extremely important work. Structural characteristics of butterfly valves and globe valves, gate valves, compared not only to avoid the result of irregular shape, uneven shell thickness, resulting in low temperature shrink, the deformation caused by thermal stress, and because small butterfly , about the basic body shape is the known, and therefore heat Plug Valvescapacity is small; to consume too little cold; shape the rules would facilitate the valves on the Cooling measures. Such as the newly developed DD363H type butterfly valve to ensure a reliable valve used in low temperature, in full accordance with the special low-temperature valve design and manufacturing, such as: shell material selection with cubic lattice 1Cr18Ni9Ti austenitic stainless steel. 2) stem bushing options: the user to reflect some 低温 valves run them, rotating parts valve occurring viscous, bite phenomenon has occurred mainly due to: matching material selection reasonable, I stay cold gap too small, and the processing precision of reasons. In the development of low-temperature valve, a series of measures to prevent the above phenomenon. For example: we stem the upper and lower bushings used with friction coefficient is small and self-lubricating properties of SF-1 composite bearings, which can be applied to some special needs of low-temperature valve. Metal Sealed Butterfly Valve has theSafety Valves features are not available in ordinary valves. In particular, small resistance, reliable seal, open and close rapidly, and long life. The company has developed three eccentric butterfly valve metal seal ring sealing force from the elastic deformation to seal, which does not require interaction with media, it can do two-way seals. According to some characteristics of butterfly valves will be valued by more people. In the future there will be more applied to the low-temperature device valve.

原文来源：http://www.1diefa.com/

2010-09-01 07:42

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