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第一章 阀门的基础知识 第一节 概述 阀门是流体管路的控制装置，其基本功能是接通或切断管路介质的流通，改变介质的流通，改变介质的流动方向，调节介质的压力和流量，保护管路的设备的正常运行。工业用的阀门的大量应用是在瓦特发明蒸汽机之后，近二三十年来，由于石油、化工、电站、冶金、船舶、核能、宇航等方面的需要，对阀门提出更高的要求，促使人们研究和生产高参数的阀门，其工作温度从超低温-269到高温1200，甚至高达3430，工作压力从超真空1.33x10-8Mpa（1x10-1 Hg）到超高压1460MPa，阀门通径从1mm 到600mm， 甚至达到9750mm，阀门的材料从铸铁，碳素钢发展到钛及钛合金，高强度耐腐蚀钢等，阀门的驱动方式从手动发展到电动、气动、液动、程控、数控、遥控等。随着现代工业的不断发展，阀门需求量不断增长，一个现代化的石油化工装置就需要上万只各式各样的阀门，阀门使用量大。开闭频繁，但往往由于制造、使用选型、维修不当， 发生跑、冒、滴、漏现象，由此引起火焰、爆炸、中毒、烫伤事故，或者造成产品质量低劣， 能耗提高，设备腐蚀，物耗提高，环境污染，甚至造成停产等事故，已屡见不鲜，因此人们希望获得高质量的阀门，同时也要求提高阀门的使用，维修水平，这时对从事阀门操作人员， 维修人员以及工程技术人员，提出新的要求，除了要精心设计、合理选用、正确操作阀门之外，还要及时维护、修理阀门，使阀门的“跑、冒、滴、漏”及各类事故降到最低限度。 第二节 阀门的分类 阀门的用途广泛，种类繁多，分类方法也比较多。总的可分两大类： 第一类自动阀门：依靠介质（液体、气体）本身的能力而自行动作的阀门。如止回阀、安全阀、调节阀、疏水阀、减压阀等。第二类驱动阀门：借助手动、电动、液动、气动来操纵动作的阀门。如闸阀，截止阀、节流阀、蝶阀、球阀、旋塞阀等。此外，阀门的分类还有以下几种方法： 一、按结构特征，根据关闭件相对于阀座移动的方向可分： 1 截门形：关闭件沿着阀座中心移动。2 闸门形：关闭件沿着垂直阀座中心移动。3 旋塞和球形：关闭件是柱塞或球，围绕本身的中心线旋转。4 旋启形；关闭件围绕阀座外的轴旋转。5 碟形：关闭件的圆盘，围绕阀座内的轴旋转。6 滑阀形：关闭件在垂直于通道的方向滑动。 二、按用途，根据阀门的不同用途可分： 1 开断用：用来接通或切断管路介质，如截止阀、闸阀、球阀、蝶阀等。2 止回用：用来防止介质倒流，如止回阀。3 调节用：用来调节介质的压力和流量，如调节阀、减压阀。4 分配用：用来改变介质流向、分配介质，如三通旋塞、分配阀、滑阀等。5 安全阀：在介质压力超过规定值时，用来排放多余的介质，保证管路系统及设备安全，如安全阀、事故阀。6 他特殊用途：如疏水阀、放空阀、排污阀等。三、按驱动方式，根据不同的驱动方式可分： 1 手动：借助手轮、手柄、杠杆或链轮等，有人力驱动，传动较大力矩时，装有 蜗轮、齿轮等减速装置。2 电动：借助电机或其他电气装置来驱动。3 液动：借助（水、油）来驱动。4 气动；借助压缩空气来驱动。四、按压力，根据阀门的公称压力可分： 1 真空阀：绝对压力0.1Mpa 即760mm 汞柱高的阀门，通常用mm 汞柱或mm 水柱表示压力。2 低压阀：公称压力PN1.6Mpa 的阀门（包括PN1.6MPa 的钢阀） 3 中压阀：公称压力PN2.56.4MPa 的阀门。4 高压阀：公称压力PN10.080.0MPa 的阀门。5 超高压阀：公称压力PN100.0MPa 的阀门。五、按介质的温度分，根据阀门工作时的介质温度可分： 1 普通阀门：适用于介质温度-40425的阀门。2 高温阀门：适用于介质温度425600的阀门。3 耐热阀门：适用于介质温度600以上的阀门。4 低温阀门：适用于介质温度-40 -150的阀门。5 超低温阀门：适用于介质温度-150以下的阀门。六、按公称通径分，根据阀门的公称通径可分：1 小口径阀门：公称通径DN40mm 的阀门。2 中口径阀门：公称通径DN50300mm 的阀门。3 大口径阀门：公称通径DN3501200mm 的阀门。4 特大口径阀门：公称通径DN1400mm 的阀门。七、按与管道连接方式分，根据阀门与管道连接方式可分； 1 法兰连接阀门：阀体带有法兰，与管道采用法兰连接的阀门。2 螺纹连接阀门：阀体带有内螺纹或外螺纹，与管道采用螺纹连接的阀门。3 焊接连接阀门：阀体带有焊口，与管道采用焊接连接的阀门。4 夹箍连接阀门：阀体上带有夹口，与管道采用夹箍连接的阀门。5 卡套连接阀门：采用卡套与管道连接的阀门。 第二章 阀门的安装、维护与操作 正确地选择了阀门之后，还要正确安装、维护与操作，这样才能充分发挥其效能。 第一节 安装 阀门安装的质量、直接影响着使用，所以必须认真注意。（一） 方向和位置 许多阀门具有方向性，例如截止阀，节流阀，减压阀、止回阀等，如果装倒装反，就会影响使用效果与寿命（如节流阀），或者根本不起作用（如减压阀），甚至造成危险（如止回阀）。一般阀门，在阀体上有方向标志；万一没有，应根据阀门的工作原理，正确识别。截止阀的阀腔左右不对称，流体要让其由下而上通过阀口，这样流体阻力小（由形状所决定），开启省力（因介质压力向上），关闭后介质不压填料，便于检修。这就是截止阀为什么不可安反的道理。其它阀门也有各自的特性。阀门安装的位置，必须方便于操作；即使安装暂时困难些，也要为操作人员的长期工作着想。最好阀门手轮与胸口取齐（一般离操作地坪1.2 米），这样，开闭阀门比较省劲。落地阀门手轮要朝上，不要倾斜，以免操作别扭。靠墙机靠设备的阀门，也要留出操作人员站立余地。要避免仰天操作，尤其是酸碱、有毒介质等，否则很不安全。闸阀不要倒装（即手轮向下），否则会使介质长期留存在阀盖空间，容易腐蚀阀杆， 而且为某些工艺要求所禁忌。同时更换填料极不方便。明杆闸阀，不要安装在地下，否则由于潮湿而腐蚀外露的阀杆。升降式止回阀，安装时要保证其阀瓣垂直，以便升降灵活。旋启式止回阀，安装时要保证其销轴水平，以便旋启灵活。 减压阀要直立安装在水平管道上，各个方向都不要倾斜。（二）施工作业安装施工必须小心，切忌撞击脆性材料制作的阀门。安装前，应将阀门作一检查，核对规格型号，鉴定有无损坏，尤其对于阀杆。还要转动几下，看是否歪斜，因为运输过程中，最易撞歪阀杆。还要清除阀内的杂物。阀门起吊时，绳子不要系在手轮或阀杆上，以免损坏这些部件，应该系在法兰上。对于阀门所连接的管路，一定要清扫干净。可用压缩空气吹去氧化铁屑、泥砂、焊渣和其他杂物。这些杂物，不但容易擦伤阀门的密封面，其中大颗粒杂物（如焊渣），还能堵死小阀门，使其失效。安装螺口阀门时，应将密封填料（线麻加铅油或聚四氟乙烯生料带），包在管子螺纹上，不要弄到阀门里，以免阀内存积，影响介质流通。安装法兰阀门时，要注意对称均匀地把紧螺栓。阀门法兰与管子法兰必须平行，间隙合理，以免阀门产生过大压力，甚至开裂。对于脆性材料和强度不高的阀门，尤其要注意。须与管子焊接的阀门，应先点焊，再将关闭件全开，然后焊死。（三）保护设施有些阀门还须有外部保护，这就是保温和保冷。保温层内有时还要加伴热蒸汽管线。什么样的阀门应该保温或保冷，要根据生产要求而定。原则地说，凡阀内介质降低温度过多， 会影响生产效率或冻坏阀门，就需要保温，甚至伴热；凡阀门裸露，对生产不利或引起结霜等不良现象时，就需要保冷。保温材料有石棉，矿渣棉、玻璃棉、珍珠岩，硅藻土、蛭石等； 保冷材料有软木、珍珠岩、泡沫、塑料等。长期不用的水、蒸汽阀门必须放掉积水。（四）旁路和仪表有的阀门，除了必要的保护设施外，还要有旁路和仪表。安装了旁路，便于疏水阀检修。其它阀门，也有安装旁路的。是否安装旁路，要看阀门状况，重要性和生产上的要求而定。（五）填料更换库存阀门，有的填料已不好使，有的与使用介质不符，这就需要更换填料。阀门制造厂无法考虑使用单位千门万类的不同介质，填料函内总是装填普通盘根，但使用时，必须让填料与介质相适应。在更换填料时，要一圈一圈地压入。每圈接缝以45 度为宜，圈与圈接缝错开180 度。填料高度要考虑压盖继续压紧的余地，现时又要让压盖下部压填料室适当深度，此深度一般可为填料室总深度的10-20%。对于要求高的阀门，接缝角度为30 度。圈与圈之间接缝错开120 度。除上述填料之处，还可根据具体情况，采用橡胶O 形环（天然橡胶耐60 摄氏度以下弱碱，丁睛橡胶耐80 摄氏度以下油品，氟橡胶耐150 摄氏度以下多种腐蚀介质）三件叠式聚四氟乙烯圈（耐200 摄氏度以下强腐蚀介质）尼龙碗状圈（耐120 摄氏度以下氨、碱）等成形填料。在普通石棉盘根外面，包一层聚四氟乙烯生料带，能提高密封效果，减轻阀杆的电化学腐蚀。在压紧填料时，要同时转动阀杆，以保持四周均匀，并防止太死，拧紧压盖要用力均匀， 不可倾斜。第二节 维护 对阀门的维护，可分两种情况；一种是保管维护，另一种是使用维护。（一）保管维护保管维护的目的，是不让阀门在保管中损坏，或降低质量。而实际上，保管不当是阀门损坏的重要原因之一。阀门保管，应该井井有条，小阀门放在货架上，大阀门可在库房地面上整齐排列，不能乱堆乱垛，不要让法兰连接面接触地面。这不仅为了美观，主要是保护阀门不致碰坏。由于保管和搬运不当，手轮打碎，阀杆碰歪，手轮与阀杆的固定螺母松脱丢失等等， 这些不必要的损失，应该避免。对短期内暂不使用的阀门，应取出石棉填料，以免产生电化学腐蚀，损坏阀杆。对刚进库的阀门，要进行检查，如在运输过程中进了雨水或污物，要擦试干净，再予存放。阀门进出口要用蜡纸或塑料片封住，以防进去脏东西。对能在大气中生锈的阀门加工面要涂防锈油，加以保护。放置室外的阀门，必须盖上油毡或苫布之类防雨、防尘物品。存放阀门的仓库要保持清洁干燥。（二）使用维护使用维护的目的，在于延长阀门寿命和保证启闭可靠。阀杆螺纹，经常与阀杆螺母摩擦，要涂一点黄干油、二硫化钼或石墨粉，起润滑作用。不经常启闭的阀门，也要定期转动手轮，对阀杆螺纹添加润滑剂，以防咬住。 室外阀门，要对阀杆加保护套，以防雨、雪、尘土锈污。如阀门系机械待动，要按时对变速箱添加润滑油。要经常保持阀门的清洁。要经常检查并保持阀门另部件完整性。如手轮的固定螺母脱落，要配齐、不能凑合使用，否则会磨园阀杆上部的四方，逐渐失去配合可靠性，乃至不能开动。不要依靠阀门支持其它重物，不要在阀门上站立。阀杆，特别是螺纹部分，要经常擦拭，对已经被尘土弄脏的润滑剂要换成新的，因为尘土中含有硬杂物，容易磨损螺纹和阀杆表面，影响使用寿命。 第三节 操作 对于阀门，不但要会安装和维护，而且还要会操作。（一）手动阀门的开闭手动阀门是使用最广的阀门，它的手轮或手柄，是按照普通的人力来设计的，考虑了密封面的强度和必要的关闭力。因此不能用长杠杆或长板手来板动。有些人习惯于使用板手， 应严格注意，不要用力过大过猛，否则容易损坏密封面，或板断手轮、手柄。启闭阀门，用力应该平稳，不可冲击。某些冲击启闭的高压阀门各部件已经考虑了这种冲击力与一般阀门不能等冈。对于蒸气阀门，开启前，应预先加热，并排除凝结水，开启时，应尽量徐缓，以免发生水击现象。当阀门全开后，应将手轮倒转少许，使螺纹之间严紧，以免松动损伤。对于明杆阀门，要记住全开和全闭时的阀杆位置，避免全开时撞击上死点。并便于检查全闭时是否正常。假如阀办脱落，或阀芯密封之间嵌入较大杂物，全闭时的阀杆位置就要变化。管路初用时，内部脏物较多，可将阀门微启，利用介质的高速流动，将其冲走，然后轻轻关闭（不能快闭、猛闭，以防残留杂质夹伤密封面），再次开启，如此重复多次，冲净脏物，再投入正常工作。常开阀门，密封面上可能粘有脏物，关闭时也要用上述方法将其冲刷干净，然后正式关严。如手轮、手柄损坏或丢失，应立即配齐，不可用活络板手代替，以免损坏阀杆四方， 启闭不灵，以致在生产中发生事故。某些介质，在阀门关闭后冷却，使阀件收缩，操作人员就应于适当时间再关闭一次， 让密封面不留细缝，否则，介质从细缝高速流过，很容易冲蚀密封面。操作时，如发现操作过于费劲，应分析原因。若填料太紧，可适当放松，如阀杆歪斜， 应通知人员修理。有的阀门，在关闭状态时，关闭件受热膨胀，造成开启困难；如必须在此时开启，可将阀盖螺纹拧松半圈至一圈，消除阀杆应力，然后板动手轮。（二）注意事项1、200以上的高温阀门，由于安装时处于常温，而正常使用后，温度升高，螺栓受热膨胀，间隙加大，所以必须再次拧紧，叫做“热紧”，操作人员要注意这一工作，否则容易发生泄露。2、天气寒冷时，水阀长期闭停，应将阀后积水排除。汽阀停汽后，也要排除凝结水。阀底有如丝堵，可将它打开排水。3、非金属阀门，有的硬脆，有的强度较低，操作时，开闭力不能太大，尤其不能使猛劲。还要注意辟免物件磕碰。4、新阀门使用时，填料不要压得太紧，以不漏为度，以免阀杆受压太大，加快磨损， 而又启闭费劲。 英文翻译： Chapter 1 basic knowledge of valve The first section outlinesThe valve is fluid pipeline control device, its basic function is to connect or cut off the pipeline medium circulation, changing the medium circulation, change the direction of the flow medium, medium pressure and flow regulation, protection of the normal operation of pipeline equipment.Industrial valve used in the invention of the steam engine, come nearly twenty or thirty years, because the petroleum, chemical, power station, metallurgy, shipbuilding, nuclear energy, aerospace and other needs, put forward higher requirement for the valve, urges the people to study and production of high parameter of valve, its working temperature from ultra low temperature - 269 DEG to 1200 DEG C high temperature, and high up to 3430 DEG C, working pressure from ultra high vacuum ( Hg 1.33x10-8Mpa 1x10-1 mm ) to a super high pressure 1460MPa, valve size from 1mm to 600mm, and even reached 9750mm, the valve material from cast iron, carbon steel to titanium and titanium alloy, high strength and corrosion resistant steel, valve drive from manual to electric, pneumatic, hydraulic, control, numerical control, remote control.With the continuous development of modern industry, the growing demand for valves, a modern petrochemical plant would require tens of thousands of every kind of valves, valve using a large amount of. Open and close and frequent, but often because of manufacturing, using selection, improper repair, run, run, drip, occurrence of leakage phenomenon, caused by fire, explosion, poisoning, scalding accidents, or cause a poor product quality, increased energy consumption, equipment corrosion, material consumption increase, environmental pollution, and even cause shutdown accident, have it is often seen., therefore, people hope to obtain high quality valves, but also to improve the valve using, repair level, then engaged in the valve operation personnel, repair personnel and engineering and technical personnel, and put forward the new requirements, in addition to carefully design, reasonable selection, correct operation of the valve, but also timely maintenance, repair the valve, the valve run run, drip, leak, and all kinds of accidents to a minimum. The second section valve classificationThe valve uses a wide range, variety, classification is more. General can be divided into two categories:The first class of automatic valve: rely on medium ( liquid, gas ) own ability and to the valve action. Such as a check valve, safety valve, regulating valve, drain valve, pressure reducing valve.Second kinds of driving valve: with the aid of the manual, electric, hydraulic, pneumatic to control the valve action. Such as gate valve, globe valve, throttle valve, butterfly valve, ball valve, plug valve.In addition, the valve classification and the following methods:One, according to the structure characteristic, according to the closure member relative to the valve seat moving direction can be divided:1: close the gate-shaped cut-off pieces along the center of the seat to move.The 2 gate shape: off pieces along the vertical center of the seat to move.3: Cock and ball closure member is a plunger or ball, around its center line of rotation.4 swing-shaped; closure around the valve axis of rotation.The 5 dish: closure disc, around the valve seat within the shaft rotation.The 6 spool valve type: closure in perpendicular to the direction of the channel sliding.In two, according to the purpose, according to the different uses can be divided:1: breaking used to connect or cut off the pipeline medium, such as cut-off valve, gate valve, ball valve, butterfly valve.2 Check: used to prevent backflow medium, such as a check valve.3: adjusting for medium pressure and flow regulation, such as regulating valve, relief valve.The 4 allocation: used to change the medium to flow, distribution medium, such as the three way cock, distribution valve, slide valve etc.Safety valve: 5 in medium pressure exceeds the set value, used to discharge the excess medium, guarantee the pipeline system and safety equipment, such as safety valve, emergency valve.In 6 he special purpose: such as drain valve, vent valve, sewage valve.Three, by driving method, according to the different driving method can be divided:1: with the aid of a handwheel, manual handle, lever or a chain wheel, a manpower driving, driving a larger torque, a worm wheel, gear deceleration device.2: with the aid of electric motor or other electrical device to drive.3: with the aid of fluid ( water, oil ) to drive.The 4 pneumatic; using compressed air to drive.In four, according to the pressure, according to the nominal pressure of the valve can be divided:1: absolute pressure vacuum valve 0.1Mpa 760mm Hg higher valve, usually with mm Hg or mm column shows the pressure.2: the low pressure valve nominal pressure PN = 1.6Mpa valve (including PN less than or equal to 1.6MPa steel valve )3 medium pressure valve: nominal pressure PN2.5 - 6.4MPa valve.4 high pressure valve: nominal pressure PN10.0 - 80.0MPa valve.5 super high pressure valve: the valve nominal pressure PN = 100.0MPa.In five, according to the temperature of the medium is divided, according to the work of the medium temperature can be divided:1: the ordinary valve suitable for medium temperature - 40 to 425 DEG C valve.2: high temperature valve suitable for medium temperature 425 to 600 DEG C valve.3: heat resistant valve for medium temperature above 600 DEG C for valve.4 cryogenic valves: applicable to the medium temperature of - 40 DEG C to - 150 degrees C. valve.5 cryogenic valve: applicable to the medium temperature of - 150 DEG C below the valve.In six, according to the nominal diameter, depending on valve size can be divided:1: small bore valve nominal diameter DN 40mm valve.2 caliber valve: nominal diameter DN50 300mm valve.3: large diameter valve nominal diameter DN350 1200mm valve.4: large diameter valve nominal diameter DN = 1400mm valve.In seven, connected with the pipeline manner, according to the valves and pipelines connecting mode can be divided;The 1 flange connected valve body with flanges, and pipe: a flange connected valve.2: thread connection valve body with internal or external threads, and the pipe with threaded connection valve.3: welded valve body with welded joints, and pipe are connected by welding valve.The 4 clamp is connected to the valve : valve with mouth, and pipeline using a clamp connection valves.5 sets of cards: card sleeve and valve connected by pipeline connecting valve. The second chapter the valve installation, maintenance and operationThe correct choice of valve, but also the correct installation, maintenance and operation, so as to give full play to its performance. The first section of the installationValve installation quality, directly affects the use, so the need for careful attention.( a ) the direction and positionMany valves has direction, such as cut-off valve, throttle valve, relief valve, check valve, if installed flip reverse, it will affect the use effect and the life ( such as throttle ), or simply does not work ( such as valve ), and even dangerous ( such as a check valve ). General valve, the valve body has a direction sign; if not, should according to the work principle, the correct recognition. The cut-off valve valve cavity left-right asymmetry, fluid to make its bottom up through the valve port, so that the fluid resistance is small (by the shape of the opening ), labor ( for medium pressure upward), after the closure of medium pressure filler, which is convenient for maintenance. This is why can not be an inverse stop valve. Other valves also have respective characteristics.The valve installed position, must facilitate the operation; even if the installation of temporary difficulties, but also for the sake of long-term operating personnel work. The best valve handwheel and chest ( above the operating floor general even 1.2 meters ), so, the valve is opened and closed more ease. Landing valve handwheel to move on, do not tilt, so as not to operate. Against the wall by the valve device, to allow the operator to stand. To avoid operation, especially acid-base, toxic medium, otherwise it is not safe to. Gate valves do not flip ( i.e. handwheel ), otherwise it will make the medium long term retention valve cap space, easy corrosion valve, but also some technology requirements of the taboo. At the same time to replace the packing is not convenient.Rising stem gate valve, not installed in the ground, or corrosion due to moisture exposed stem.Lift check valve, when the valve installation to ensure its vertical, so that the flexible lifting.Swing check valve, installation to ensure its pin level, so as to swing and flexible.Pressure reducing valve to the upright installed in horizontal pipelines, all directions do not tilt.( two) construction workInstallation and construction must be careful to avoid collision, brittle material valve.Before the installation, should be a check valve, check the specifications, there is no damage identification, especially for the valve stem. Also a few turns, to see whether the skew, because the transport process, the most easily break valve. Will purge valve within the debris. Valve lifting rope, not in the hand wheel or the stem, so as to avoid damage to these components, should be in the flange. The valve connecting pipe, must be clean. By compressing the air blowing to iron oxide particles, sand, slag and other debris. These impurities, not only easy to scratch the sealing surface of the valve, wherein large granular debris ( such as welding slag ), also blocked the small valve, so that its failure.Mounting screw valves, should be sealed packing ( hemp lead oil or Teflon tape ), wrapped in a pipe thread, do not get to the valve, so as to avoid the valve memory product, affect the medium circulation.Mounting flange valve, to the attention of symmetrical evenly tightened the bolts. The valve flange and pipe flange must be parallel, gap reasonable, so as to avoid excessive pressure valve, and even cracking. For brittle materials and the intensity is not high valve, paying particular attention to the. To the valve and pipe welding, spot welding should be first, then the closure member to open, and then welding die.( three) protection facilitiesSome valves must have external protection, this is the heat preservation and insulation. The insulation layer is sometimes added to the heat steam pipeline. What kind of valve should be heat or cold, according to the requirements of production and. In principle, where the medium in the valve reduces the temperature too much, will affect the production efficiency or frozen valve, requires insulation, even heating; where the valve is exposed, to produce adverse or caused by frost and other undesirable phenomena, we need cold. Insulation materials, asbestos, mineral wool, glass wool, perlite, vermiculite, diatomite; cold insulation materials are cork, perlite, foam, plastic etc. Without water, steam valve must be drained water.( four) bypass and instrumentSome valves, except for the necessary protection facilities, but also has a bypass and instrument. Install bypass, convenient drainage valve maintenance. Other valves, also install bypass. Whether to install bypass, to see the valve status, importance and the requirements of production and.( five) packing replacementStock valve, some packing has been not so, some with the use of dielectric mismatch, which requires the replacement of packing.Valve factory is unable to consider the use of units of thousand doors million class in different media, the stuffing box is always filled with a common root, but when in use, must let the filler and the medium is adapted to.In the replacement of the stuffing, to a circle press. Each lap joint with 45 degrees appropriate, ring and ring seam stagger 180 degrees. Filler height to consider gland continue pressing room, now to cover lower pressure packing chamber proper depth, the depth the general for the packing chamber total depth of 10-20%.For the high requirements for the valve, joint angle of 30 degrees. Circle and circle seam stagger between 120 degrees.In addition to the filler, can also be based on specific circumstances, adopt rubber O ring ( natural rubber resistant to 60 degrees Celsius below weak base, acrylonitrile butadiene rubber resistant to 80 degrees Celsius below oil, fluorine rubber resistant to 150 degrees Celsius below various corrosive medium ) three stacked PTFE ring ( resistant to 200 degrees Celsius below the strong corrosive medium ) nylon bowl shaped ring ( resistant to 120 degrees Celsius below ammonia, alkali ), forming filler. In ordinary asbestos packing outside, coated with a layer of Teflon belt, can improve the sealing effect, relieve stem electrochemical corrosion.In packing, valve stem to rotate at the same time, in order to keep around evenly, and to prevent too much death, tighten the cap evenly, Do not tilt.Section second maintenanceOn valve maintenance, can be divided into two kinds of circumstances; one is the preservation, another is the use of maintenance.( a ) maintainKeeping maintenance purposes, is not that the valve in the custody of the damage, or lower quality. But in fact, improper keeping is one of the important reasons for the damage of the valve. The valve should be arranged in good order, storage, small valve on the shelf, valves in the storehouse surface with regular arrangement, not a disorderly pile, dont let the flange joint surface in contact with the ground. This not only in appearance, is mainly protects the valve from damage. The safekeeping and improper handling, hand wheel broken, stem touch askew, the handwheel and the stem of the fixed nut loose loss etc, these unnecessary losses, should avoid. On the short term not used valves, should remove the asbestos packing, in order to avoid electrochemical co
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