畢業(yè)設計——閥門 外文文獻翻譯 中英文

第一章 閥門的基礎知識 第一節(jié) 概述 閥門是流體管路的控制裝置，其基本功能是接通或切斷管路介質的流通，改變介質的流通，改變介質的流動方向，調節(jié)介質的壓力和流量，保護管路的設備的正常運行。工業(yè)用的閥門的大量應用是在瓦特發(fā)明蒸汽機之后，近二三十年來，由于石油、化工、電站、冶金、船舶、核能、宇航等方面的需要，對閥門提出更高的要求，促使人們研究和生產高參數(shù)的閥門，其工作溫度從超低溫-269到高溫1200，甚至高達3430，工作壓力從超真空1.33x10-8Mpa（1x10-1 Hg）到超高壓1460MPa，閥門通徑從1mm 到600mm， 甚至達到9750mm，閥門的材料從鑄鐵，碳素鋼發(fā)展到鈦及鈦合金，高強度耐腐蝕鋼等，閥門的驅動方式從手動發(fā)展到電動、氣動、液動、程控、數(shù)控、遙控等。隨著現(xiàn)代工業(yè)的不斷發(fā)展，閥門需求量不斷增長，一個現(xiàn)代化的石油化工裝置就需要上萬只各式各樣的閥門，閥門使用量大。開閉頻繁，但往往由于制造、使用選型、維修不當， 發(fā)生跑、冒、滴、漏現(xiàn)象，由此引起火焰、爆炸、中毒、燙傷事故，或者造成產品質量低劣， 能耗提高，設備腐蝕，物耗提高，環(huán)境污染，甚至造成停產等事故，已屢見不鮮，因此人們希望獲得高質量的閥門，同時也要求提高閥門的使用，維修水平，這時對從事閥門操作人員， 維修人員以及工程技術人員，提出新的要求，除了要精心設計、合理選用、正確操作閥門之外，還要及時維護、修理閥門，使閥門的“跑、冒、滴、漏”及各類事故降到最低限度。 第二節(jié) 閥門的分類 閥門的用途廣泛，種類繁多，分類方法也比較多。總的可分兩大類： 第一類自動閥門：依靠介質（液體、氣體）本身的能力而自行動作的閥門。如止回閥、安全閥、調節(jié)閥、疏水閥、減壓閥等。第二類驅動閥門：借助手動、電動、液動、氣動來操縱動作的閥門。如閘閥，截止閥、節(jié)流閥、蝶閥、球閥、旋塞閥等。此外，閥門的分類還有以下幾種方法： 一、按結構特征，根據(jù)關閉件相對于閥座移動的方向可分： 1 截門形：關閉件沿著閥座中心移動。2 閘門形：關閉件沿著垂直閥座中心移動。3 旋塞和球形：關閉件是柱塞或球，圍繞本身的中心線旋轉。4 旋啟形；關閉件圍繞閥座外的軸旋轉。5 碟形：關閉件的圓盤，圍繞閥座內的軸旋轉。6 滑閥形：關閉件在垂直于通道的方向滑動。 二、按用途，根據(jù)閥門的不同用途可分： 1 開斷用：用來接通或切斷管路介質，如截止閥、閘閥、球閥、蝶閥等。2 止回用：用來防止介質倒流，如止回閥。3 調節(jié)用：用來調節(jié)介質的壓力和流量，如調節(jié)閥、減壓閥。4 分配用：用來改變介質流向、分配介質，如三通旋塞、分配閥、滑閥等。5 安全閥：在介質壓力超過規(guī)定值時，用來排放多余的介質，保證管路系統(tǒng)及設備安全，如安全閥、事故閥。6 他特殊用途：如疏水閥、放空閥、排污閥等。三、按驅動方式，根據(jù)不同的驅動方式可分： 1 手動：借助手輪、手柄、杠桿或鏈輪等，有人力驅動，傳動較大力矩時，裝有 蝸輪、齒輪等減速裝置。2 電動：借助電機或其他電氣裝置來驅動。3 液動：借助（水、油）來驅動。4 氣動；借助壓縮空氣來驅動。四、按壓力，根據(jù)閥門的公稱壓力可分： 1 真空閥：絕對壓力<0.1Mpa 即760mm 汞柱高的閥門，通常用mm 汞柱或mm 水柱表示壓力。2 低壓閥：公稱壓力PN1.6Mpa 的閥門（包括PN1.6MPa 的鋼閥） 3 中壓閥：公稱壓力PN2.56.4MPa 的閥門。4 高壓閥：公稱壓力PN10.080.0MPa 的閥門。5 超高壓閥：公稱壓力PN100.0MPa 的閥門。五、按介質的溫度分，根據(jù)閥門工作時的介質溫度可分： 1 普通閥門：適用于介質溫度-40425的閥門。2 高溫閥門：適用于介質溫度425600的閥門。3 耐熱閥門：適用于介質溫度600以上的閥門。4 低溫閥門：適用于介質溫度-40 -150的閥門。5 超低溫閥門：適用于介質溫度-150以下的閥門。六、按公稱通徑分，根據(jù)閥門的公稱通徑可分：1 小口徑閥門：公稱通徑DN<40mm 的閥門。2 中口徑閥門：公稱通徑DN50300mm 的閥門。3 大口徑閥門：公稱通徑DN3501200mm 的閥門。4 特大口徑閥門：公稱通徑DN1400mm 的閥門。七、按與管道連接方式分，根據(jù)閥門與管道連接方式可分； 1 法蘭連接閥門：閥體帶有法蘭，與管道采用法蘭連接的閥門。2 螺紋連接閥門：閥體帶有內螺紋或外螺紋，與管道采用螺紋連接的閥門。3 焊接連接閥門：閥體帶有焊口，與管道采用焊接連接的閥門。4 夾箍連接閥門：閥體上帶有夾口，與管道采用夾箍連接的閥門。5 卡套連接閥門：采用卡套與管道連接的閥門。 第二章 閥門的安裝、維護與操作 正確地選擇了閥門之后，還要正確安裝、維護與操作，這樣才能充分發(fā)揮其效能。 第一節(jié) 安裝 閥門安裝的質量、直接影響著使用，所以必須認真注意。（一） 方向和位置 許多閥門具有方向性，例如截止閥，節(jié)流閥，減壓閥、止回閥等，如果裝倒裝反，就會影響使用效果與壽命（如節(jié)流閥），或者根本不起作用（如減壓閥），甚至造成危險（如止回閥）。一般閥門，在閥體上有方向標志；萬一沒有，應根據(jù)閥門的工作原理，正確識別。截止閥的閥腔左右不對稱，流體要讓其由下而上通過閥口，這樣流體阻力小（由形狀所決定），開啟省力（因介質壓力向上），關閉后介質不壓填料，便于檢修。這就是截止閥為什么不可安反的道理。其它閥門也有各自的特性。閥門安裝的位置，必須方便于操作；即使安裝暫時困難些，也要為操作人員的長期工作著想。最好閥門手輪與胸口取齊（一般離操作地坪1.2 米），這樣，開閉閥門比較省勁。落地閥門手輪要朝上，不要傾斜，以免操作別扭?？繅C靠設備的閥門，也要留出操作人員站立余地。要避免仰天操作，尤其是酸堿、有毒介質等，否則很不安全。閘閥不要倒裝（即手輪向下），否則會使介質長期留存在閥蓋空間，容易腐蝕閥桿， 而且為某些工藝要求所禁忌。同時更換填料極不方便。明桿閘閥，不要安裝在地下，否則由于潮濕而腐蝕外露的閥桿。升降式止回閥，安裝時要保證其閥瓣垂直，以便升降靈活。旋啟式止回閥，安裝時要保證其銷軸水平，以便旋啟靈活。 減壓閥要直立安裝在水平管道上，各個方向都不要傾斜。（二）施工作業(yè)安裝施工必須小心，切忌撞擊脆性材料制作的閥門。安裝前，應將閥門作一檢查，核對規(guī)格型號，鑒定有無損壞，尤其對于閥桿。還要轉動幾下，看是否歪斜，因為運輸過程中，最易撞歪閥桿。還要清除閥內的雜物。閥門起吊時，繩子不要系在手輪或閥桿上，以免損壞這些部件，應該系在法蘭上。對于閥門所連接的管路，一定要清掃干凈。可用壓縮空氣吹去氧化鐵屑、泥砂、焊渣和其他雜物。這些雜物，不但容易擦傷閥門的密封面，其中大顆粒雜物（如焊渣），還能堵死小閥門，使其失效。安裝螺口閥門時，應將密封填料（線麻加鉛油或聚四氟乙烯生料帶），包在管子螺紋上，不要弄到閥門里，以免閥內存積，影響介質流通。安裝法蘭閥門時，要注意對稱均勻地把緊螺栓。閥門法蘭與管子法蘭必須平行，間隙合理，以免閥門產生過大壓力，甚至開裂。對于脆性材料和強度不高的閥門，尤其要注意。須與管子焊接的閥門，應先點焊，再將關閉件全開，然后焊死。（三）保護設施有些閥門還須有外部保護，這就是保溫和保冷。保溫層內有時還要加伴熱蒸汽管線。什么樣的閥門應該保溫或保冷，要根據(jù)生產要求而定。原則地說，凡閥內介質降低溫度過多， 會影響生產效率或凍壞閥門，就需要保溫，甚至伴熱；凡閥門裸露，對生產不利或引起結霜等不良現(xiàn)象時，就需要保冷。保溫材料有石棉，礦渣棉、玻璃棉、珍珠巖，硅藻土、蛭石等； 保冷材料有軟木、珍珠巖、泡沫、塑料等。長期不用的水、蒸汽閥門必須放掉積水。（四）旁路和儀表有的閥門，除了必要的保護設施外，還要有旁路和儀表。安裝了旁路，便于疏水閥檢修。其它閥門，也有安裝旁路的。是否安裝旁路，要看閥門狀況，重要性和生產上的要求而定。（五）填料更換庫存閥門，有的填料已不好使，有的與使用介質不符，這就需要更換填料。閥門制造廠無法考慮使用單位千門萬類的不同介質，填料函內總是裝填普通盤根，但使用時，必須讓填料與介質相適應。在更換填料時，要一圈一圈地壓入。每圈接縫以45 度為宜，圈與圈接縫錯開180 度。填料高度要考慮壓蓋繼續(xù)壓緊的余地，現(xiàn)時又要讓壓蓋下部壓填料室適當深度，此深度一般可為填料室總深度的10-20%。對于要求高的閥門，接縫角度為30 度。圈與圈之間接縫錯開120 度。除上述填料之處，還可根據(jù)具體情況，采用橡膠O 形環(huán)（天然橡膠耐60 攝氏度以下弱堿，丁睛橡膠耐80 攝氏度以下油品，氟橡膠耐150 攝氏度以下多種腐蝕介質）三件疊式聚四氟乙烯圈（耐200 攝氏度以下強腐蝕介質）尼龍碗狀圈（耐120 攝氏度以下氨、堿）等成形填料。在普通石棉盤根外面，包一層聚四氟乙烯生料帶，能提高密封效果，減輕閥桿的電化學腐蝕。在壓緊填料時，要同時轉動閥桿，以保持四周均勻，并防止太死，擰緊壓蓋要用力均勻， 不可傾斜。第二節(jié) 維護 對閥門的維護，可分兩種情況；一種是保管維護，另一種是使用維護。（一）保管維護保管維護的目的，是不讓閥門在保管中損壞，或降低質量。而實際上，保管不當是閥門損壞的重要原因之一。閥門保管，應該井井有條，小閥門放在貨架上，大閥門可在庫房地面上整齊排列，不能亂堆亂垛，不要讓法蘭連接面接觸地面。這不僅為了美觀，主要是保護閥門不致碰壞。由于保管和搬運不當，手輪打碎，閥桿碰歪，手輪與閥桿的固定螺母松脫丟失等等， 這些不必要的損失，應該避免。對短期內暫不使用的閥門，應取出石棉填料，以免產生電化學腐蝕，損壞閥桿。對剛進庫的閥門，要進行檢查，如在運輸過程中進了雨水或污物，要擦試干凈，再予存放。閥門進出口要用蠟紙或塑料片封住，以防進去臟東西。對能在大氣中生銹的閥門加工面要涂防銹油，加以保護。放置室外的閥門，必須蓋上油氈或苫布之類防雨、防塵物品。存放閥門的倉庫要保持清潔干燥。（二）使用維護使用維護的目的，在于延長閥門壽命和保證啟閉可靠。閥桿螺紋，經常與閥桿螺母摩擦，要涂一點黃干油、二硫化鉬或石墨粉，起潤滑作用。不經常啟閉的閥門，也要定期轉動手輪，對閥桿螺紋添加潤滑劑，以防咬住。 室外閥門，要對閥桿加保護套，以防雨、雪、塵土銹污。如閥門系機械待動，要按時對變速箱添加潤滑油。要經常保持閥門的清潔。要經常檢查并保持閥門另部件完整性。如手輪的固定螺母脫落，要配齊、不能湊合使用，否則會磨園閥桿上部的四方，逐漸失去配合可靠性，乃至不能開動。不要依靠閥門支持其它重物，不要在閥門上站立。閥桿，特別是螺紋部分，要經常擦拭，對已經被塵土弄臟的潤滑劑要換成新的，因為塵土中含有硬雜物，容易磨損螺紋和閥桿表面，影響使用壽命。 第三節(jié) 操作 對于閥門，不但要會安裝和維護，而且還要會操作。（一）手動閥門的開閉手動閥門是使用最廣的閥門，它的手輪或手柄，是按照普通的人力來設計的，考慮了密封面的強度和必要的關閉力。因此不能用長杠桿或長板手來板動。有些人習慣于使用板手， 應嚴格注意，不要用力過大過猛，否則容易損壞密封面，或板斷手輪、手柄。啟閉閥門，用力應該平穩(wěn)，不可沖擊。某些沖擊啟閉的高壓閥門各部件已經考慮了這種沖擊力與一般閥門不能等岡。對于蒸氣閥門，開啟前，應預先加熱，并排除凝結水，開啟時，應盡量徐緩，以免發(fā)生水擊現(xiàn)象。當閥門全開后，應將手輪倒轉少許，使螺紋之間嚴緊，以免松動損傷。對于明桿閥門，要記住全開和全閉時的閥桿位置，避免全開時撞擊上死點。并便于檢查全閉時是否正常。假如閥辦脫落，或閥芯密封之間嵌入較大雜物，全閉時的閥桿位置就要變化。管路初用時，內部臟物較多，可將閥門微啟，利用介質的高速流動，將其沖走，然后輕輕關閉（不能快閉、猛閉，以防殘留雜質夾傷密封面），再次開啟，如此重復多次，沖凈臟物，再投入正常工作。常開閥門，密封面上可能粘有臟物，關閉時也要用上述方法將其沖刷干凈，然后正式關嚴。如手輪、手柄損壞或丟失，應立即配齊，不可用活絡板手代替，以免損壞閥桿四方， 啟閉不靈，以致在生產中發(fā)生事故。某些介質，在閥門關閉后冷卻，使閥件收縮，操作人員就應于適當時間再關閉一次， 讓密封面不留細縫，否則，介質從細縫高速流過，很容易沖蝕密封面。操作時，如發(fā)現(xiàn)操作過于費勁，應分析原因。若填料太緊，可適當放松，如閥桿歪斜， 應通知人員修理。有的閥門，在關閉狀態(tài)時，關閉件受熱膨脹，造成開啟困難；如必須在此時開啟，可將閥蓋螺紋擰松半圈至一圈，消除閥桿應力，然后板動手輪。（二）注意事項1、200以上的高溫閥門，由于安裝時處于常溫，而正常使用后，溫度升高，螺栓受熱膨脹，間隙加大，所以必須再次擰緊，叫做“熱緊”，操作人員要注意這一工作，否則容易發(fā)生泄露。2、天氣寒冷時，水閥長期閉停，應將閥后積水排除。汽閥停汽后，也要排除凝結水。閥底有如絲堵，可將它打開排水。3、非金屬閥門，有的硬脆，有的強度較低，操作時，開閉力不能太大，尤其不能使猛勁。還要注意辟免物件磕碰。4、新閥門使用時，填料不要壓得太緊，以不漏為度，以免閥桿受壓太大，加快磨損， 而又啟閉費勁。 英文翻譯： 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