1、1Basic Mechanical Seals密封基础知识密封基础知识JC Tianjin Training2rotating seal unittwo flat sliding surfaces, which maintain a close running clearance while separated by a fluid film两个光滑平面之间维持着一个由流体膜隔开的微小间隙两个光滑平面之间维持着一个由流体膜隔开的微小间隙stationary seal unitWhat is a mechanical seal?什么是机械密封？什么是机械密封？Desired Features o
2、f a Seal机械密封必须有的特征机械密封必须有的特征lLong-life 很长的寿命lEasy maintenance 容易检修lLow cost 低成本nSmall axial clearance 小的轴向间隙小的轴向间隙nSelf adjusting 自调节自调节Shaft Movement轴的运动轴的运动4Basic Mechanical Seal基础机械密封基础机械密封15Basic Mechanical Seal基础机械密封基础机械密封26Basic Mechanical Seal基础机械密封基础机械密封37Basic Mechanical Seal基础机械密封基础机械密封48B
3、asic Mechanical Seal基础机械密封基础机械密封59Basic Mechanical Seal基础机械密封基础机械密封SEATSPRING OR SPRING FORCEO-Ring O型圈型圈Shaft轴轴Mating Ring配合环配合环Primary Ring补偿环补偿环Snap Ring卡环卡环Anti-X Ring 挡环挡环O-Ring O型圈型圈Disk推环推环Springs弹簧弹簧Retainer传动套传动套Set Screw定位螺丝定位螺丝An Example of a Complete Seal一个完整密封的例子一个完整密封的例子Simply put, a m
4、echanical seal is:简单的说简单的说,机械密封就是机械密封就是:1. A wearable, stationary, primary sealing element 一个耐磨,静止的密封件2. A wearable, rotating, primary sealing element 一个耐磨,旋转的密封件3. A secondary sealing element 二次密封4. A mechanical loading device to press primary sealing elements 1 and 2 against one another, and 使件1和件
5、2相互贴合的机械装置5. Auxiliary components to complete seal 使密封更加完善的辅助件12l不像一个机械密封而更像一个限制装置,需要泄漏否则将会灼伤.l会磨损轴或轴套l高功耗用来克服磨擦l产品损失l需要大量的水l安装,维修和盘根调整需要停车时间l泄漏导致设备破坏和摧毁l不可见泄漏、机械密封和盘根之间的泄漏率在1到100或者更好l证明机械密封的寿命可达8到10年毫无故障l无产品损失,节省水和能量可以节省成本l安装后维修很少l密封有潜在危害的物质时机械密封可以提供更好的安全性Gland Packing v. Mechanical Seals盘根和机械密封盘根和
6、机械密封13 SPRING FORCEFLUID PRESSUREfluid film (3 - 5 microns)a thin film of liquid forms the primary (dynamic) seal between the rotating and stationary elements在旋转件和在旋转件和静止件之间形成很薄的液膜静止件之间形成很薄的液膜FILM REACTIONPrimary Seal 主密封主密封14Primary Seal Film Thickness主密封主密封膜厚度膜厚度15Primary Seal Film Thickness主密封主密封
7、膜厚度膜厚度lFluid film thickness is very importanttoo thin - wear, causing early seal failuretoo thick - visible leakagelMust be:present - beware dry running谨防干运转Stable稳定 谨防磨损征兆clean - beware abrasive wear symptomsreasonable viscosity合理的黏度temperature controlled受控的温度acceptable pressure允许的压力16Primary Seal
8、Face Flatness主密封主密封平面平面Lubricant 润滑剂润滑剂Separation分离面分离面Magnified Surface A 放大面放大面Magnified Surface B 放大面放大面Heat热量热量The Sealing Interface 密封面密封面lLubrication Purpose: 润滑目的Separate surfaces分离两个面Prevent contact of high surface points防止出现面接触Reduce friction/heat generation减少摩擦/生热Process Fluid Acts as Lubr
9、icant Between Faces流体在两个面之间充当润滑剂的流体在两个面之间充当润滑剂的过程过程Gland密封端盖密封端盖Pump Housing泵腔泵腔Process Fluid工艺流体工艺流体Invisible Leakage: 不可见泄漏不可见泄漏Fluid Evaporates Upon Reaching Atmosphere微量的泄漏在大气侧蒸发微量的泄漏在大气侧蒸发 Primary Ring补偿环补偿环Mating Ring配合环配合环Gland密封端盖密封端盖Pump Housing泵腔泵腔No Fluid Or Dry Running没有流体或者干运转没有流体或者干运转P
10、rimary Ring补偿环补偿环Mating Ring配合环配合环Without Lubrication, Faces Run Dry And Overheat没有润滑干运转导致过热没有润滑干运转导致过热20常用动环材料常用动环材料 lFace (Primary Ring) Materials 动环材料Carbon-graphite 碳石墨类lresin impregnated 树脂浸渍 （171）lantimony impregnated 金属锑浸渍 （218）Carbon converted to Silicon Carbide 硅化石墨（121）lCVR 化学汽相反应硅化石墨lCVD
11、化学汽相沉积硅化石墨Solid Silicon Carbide 碳化硅lSintered silicon carbide 无压烧结碳化硅 (277)lReaction silicon carbide 反应烧结碳化硅（088）lSintered silicon carbide with controlled porosity 微孔碳化硅 （584）Tungsten Carbide 碳化钨lCobalt bonded 钴基碳化钨（025）lNickel bonded 镍基碳化钨（005）21常用静环材料常用静环材料 Seat (Mating Ring-Narrow) Materials 静环材料C
12、eramic 陶瓷l99.7% Aluminium Oxide 氧化铝 (059)Solid Silicon Carbide 碳化硅lSintered silicon carbide 无压烧结碳化硅 (277)lReaction silicon carbide 反应烧结碳化硅（088）lSintered silicon carbide with controlled porosity 微孔碳化硅 （584）Tungsten Carbide 碳化钨lCobalt bonded 钴基碳化钨（025）lNickel bonded 镍基碳化钨（005）22Secondary Seal 二次密封二次密封
13、lThree basic formsl三种基本形式o-rings o型圈Wedges 楔形环Bellows 波纹管lElastomer 橡胶的lMetal 金属的Formed 成型的成型的edge welded 焊接的焊接的lPTFElTwo groupsPusher推进式Sliding滑移lo-rings wedgesNon-pusher非推进式lBellows风箱Teflon Bellows聚四氟乙烯聚四氟乙烯波纹管波纹管Elastomeric Bellows橡胶波纹管橡胶波纹管Half Convolution半波半波Welded Metal Bellows焊接金属波纹管焊接金属波纹管V
14、RingsV型圈型圈U Cup杯型杯型Wedge楔形楔形Encapsulated O Ring包覆包覆 O型圈型圈O RingO型圈型圈Secondary Sealing Elements二次密封二次密封Pusher推进式推进式Non-Pusher非推进式非推进式O-ring secondary seal must slide along shaft as seal face wearsO型圈二次密封在密封面磨型圈二次密封在密封面磨损的时候必须能够沿轴滑动损的时候必须能够沿轴滑动Bellows secondary sealexpands to accommodateface wear. Bel
15、lows tail is stationary against shaft.波纹管伸长能够补偿密封面磨波纹管伸长能够补偿密封面磨损损,波纹管尾部与轴保持静止波纹管尾部与轴保持静止vs.Pusher vs. Non-Pusher推进式推进式/非推进式非推进式25Secondary Seal: Pusher二次密封：推进式二次密封：推进式26Secondary Seal: Pusher二次密封：推进式二次密封：推进式lAdvantages 优点sudden failure very unlikely 几乎不会突发意外事故higher pressure capability - face not s
16、tressed 耐压性能高-应力变形小wide choice of materials for all components 所有成分的材料选择广泛field repairable可修复的Disadvantages 缺点hang-up (not likely where o-ring is well isolated) 挂起permanent set / pressure problems (cause hang-up)长久放置/压力问题（导致挂起）excellent shaft surface finish required要求轴的表面光滑maximum temperature +260C
17、最高温度+260C 27Pusher Seal: Hang-up推进式密封：挂起推进式密封：挂起28Secondary Seal: O-Ring二次密封：二次密封：O型圈型圈29Secondary Seal: Wedge二次密封：楔形环二次密封：楔形环 30Secondary Seal: Non-Pusher二次密封：非推进式二次密封：非推进式31Secondary Seal: Bellows二次密封：波纹管二次密封：波纹管32Secondary Seal: Metal Bellows二次密封：金属波纹管二次密封：金属波纹管static o-ring静止静止o型圈型圈33Secondary S
18、eal: PTFE Bellows二次密封：二次密封：PTFE波纹管波纹管Tertiary Seal 三次密封三次密封35Tertiary Seal 三次密封三次密封lPrevents leakage round mating ring 防止静环周围的泄漏lSometimes also prevents mating ring rotationl有时也防止静环旋转36Tertiary Seal 三次密封三次密封lFour basic types 四种基本的形式O-rings O型圈lElastomers 橡胶Seat Rings (square or rectangular section)l
19、PTFElgraphiteCup RingslelastomersGaskets or Flat JointslPTFElcompressed fibre非石棉的压缩纤维Tertiary Seal: O-ring三次密封：三次密封：O型环型环Tertiary Seal: O-ring三次密封：三次密封：O型环型环Tertiary Seal: O-ring三次密封：三次密封：O型环型环40Tertiary Seal: Seat Ring三次密封：静环三次密封：静环Tertiary Seal: Cup Rubber三次密封：三次密封：Spring Design Features 弹弹簧设计特点簧设
20、计特点lSprings 弹簧Provide The Initial Closing Force提供初始闭合力Are Very Important At Low Pressures低压下很重要Are Not So Important At High Pressures高压下不重要Design Features 设计特点设计特点lSprings 弹簧Single 单弹簧Multiple 多弹簧Bellows 波纹管Wave 波形Design Features 设计特点设计特点lSprings 弹簧High Speed Seals Use Stationary Springs (5000 ft/mi
21、n Typical Break Point) 高速机械密封使用静止弹簧(5000ft/min 典型的分界点)Design Features 设计特点设计特点lSprings 弹簧Corrosion 腐蚀Clogging 堵塞Uniformity Of Load 负荷一致Inventory 批量lDrive Mechanism 驱动机械Must Transmit Torque 必须能够传递转矩Must Allow Axial Movement (Primary Ring) 必须能够使动环轴向运动Types of Drive Mechanisms 驱动机械的类型驱动机械的类型Pin Drive 销
22、驱动销驱动 Dent Drive凹窝驱动凹窝驱动Slot and Ear槽和支耳槽和支耳Spring Drive弹簧驱动弹簧驱动Set Screw Drive定位螺丝驱动定位螺丝驱动Snap Ring Drive卡环驱动卡环驱动Elastomer Drive橡胶驱动橡胶驱动Key Drive键驱动键驱动Types of Drive Mechanisms 驱动机械的类型驱动机械的类型48Seal Materials 密封材料密封材料Material Considerations 材料需要考虑Temperature 温度Thermal Expansion 热膨胀Thermal Conductivi
23、ty 导热性Chemical Resistance化学稳定性Wear 磨损性Flexibility 弹性Manufacturability 制造能力Cost 成本Availability 实用性49Primary Seal Materials主密封材料主密封材料lFace (Primary Ring-Narrow) Materials 窄环材料Carbon-graphite 炭-石墨 lresin impregnated 浸渍树脂lantimony impregnated 浸渍金属锑Carbon converted to Silicon Carbide 硅化石墨50Primary Seal M
24、aterials主密封材料主密封材料51Primary Seal Materials主密封材料主密封材料52Primary Seal Materials主密封材料主密封材料lSeat (Mating Ring) Materials 静环材料 Solid Silicon Carbide碳化硅l pure sintered 常压烧结l reaction bonded 反映烧结 Tungsten Carbide 硬质合金l nickel or cobalt bonded.镍基或钴基Ni-resist 高镍铸铁lhigh nickel cast iron; austenitic cast iron奥氏
25、体铸铁Ceramic 陶瓷l99.7% aluminium oxide 99.7%氧化铝53Primary Seal Materials主密封材料主密封材料ceramic mating ring54Material Properties 材料性质材料性质-400癋癋-200癋癋0400癋癋600 F200癋癋Buna-NEPDMVitonTM-54癈癈 / -65癋癋149癈癈 / 300癋癋121癈癈 / 250癋癋-240癈癈-129癈癈-18癈癈204癈癈316 C93癈癈AflasTM204癈癈 / 400癋癋204癈癈 / 400癋癋-45癈癈 / -50癋癋-29癈癈 / -20癋癋TeflonTM287癈癈 / 550癋癋-212癈癈 / -350癋癋-29癈癈 / -20癋癋KalrezTM287癈癈 / 550癋癋-40癈癈 / -40癋癋Secondary Sealing Elements Temperature Range二次密封二次密封温度范围温度范围56Seal Materials 密封材料密封材料Parker O-Ring Compatibility Table
