密封垫的选用.doc

密封垫的选用密封垫的选用原则是：对于要求不高的场合，可凭经验来选取，不合适时再更换。但对那些要求严格的场合，例如易爆、剧毒和可燃性气体以及强腐蚀的液体设备、反应罐和输送管道系统等，则应根据工作压力、工作温度、密封介质的腐蚀性及结合密封面的形式来选用。一般来讲，在常温低压时，选用非金属软密封垫；中压高温时，选用非金属与金属组合密封垫或金属密封垫；在温度、压力有较大波动时，选用弹性好的或自紧式密封垫；在低温、腐蚀性介质或真空条件下应考虑密封垫的特殊性能。这里特别需要说明的是法兰情况对垫片选择的影响。（1）法兰形式的影响法兰形式不同，要求使用的垫片也不同。光滑面法兰一般只用于低压，配软质的薄密封垫；在高压下，如果法兰的强度足够，也可以用光滑面法兰，但应该用厚软质垫，或者用带内加强环或外加强环的缠绕密封垫。在这种场合，金属垫片也不适用，因为这时要求的压紧力过大，导致螺栓较大的变形，使法兰不易封严。如果要用金属垫片，则应将光滑面缩小，使其与垫片的接触面积减小。这样，在螺栓张力相同的情况下，缩小后的窄光滑面的压紧应力就会增大。（2）法兰表面粗糙度的影响法兰表面粗糙度对密封效果影响很大，特别是当采用非软质垫片时，密封表面粗糙度是造成泄漏的主要原因之一。例如，车削法兰面的刀纹是螺旋线，使用金属垫片时，如果粗糙度值较大，垫片就不能堵死刀纹所形成的这条螺旋槽，在压力作用下，介质就会顺着这条沟槽泄漏出来。软质密封垫对法兰面的光洁程度要求低得多。这是因为它容易变形，能够堵死加工刀纹，从而防止了泄漏。对软质垫片，法兰而过于光滑反而不利，因为此时发生界面泄漏的阻力变小了。所以，垫片不同，所要求的法兰面的粗糙度也不相同。表29.3-15列出了各种密封垫所要求的法兰表面粗糙度的经验数据。（3）法兰与垫片的硬度差使用垫片的目的在于使垫片产生弹性或塑性变形以填满法兰面微小凸凹不平，阻止泄漏发生。因而应使垫片材料的硬度低于法兰材料的硬度，二者之间相差越大，实现密封就越容易。当使用金属垫片时，为了保证实现密封，应尽可能选用较软的材料，使金属垫片的硬度比法兰硬度低40HB以上为宜。表29.3-16为石油部垫片选用标准。表29.3-17为橡胶石棉板厚度及适用范围。 表29.3-15 法兰密封而的表面粗糙度垫片类型垫片名称表面粗糙度备注金属密封垫环形垫片0.8自紧式密封垫希望表面越光越好锯齿形垫片1.6半金属密封垫金属包垫片1.6缠绕垫片12.5缠绕垫片3.2气体密封时石棉橡胶板12.5石棉布密封垫25聚四氟乙烯密封垫聚四氟乙烯板垫片12.5聚四氟乙烯包垫片12.5橡胶板25有机物密封垫油封25皮革密封垫25纸垫25表29.3-16 石油部垫片选用标准 介质法兰公称压力/MPa介质温度/法兰密封面形式选用垫片名称垫片材料油气、油品、液化气、氢气、硫化催化剂（丙烷、丙酮、苯、酚、糠醛、异丙醇）、小于25%的尿素（质量分数）1.6200光滑式耐油橡胶石棉垫片耐油橡胶石棉板1.6201300光滑式缠绕式垫片08（15）钢带、石棉带2.5200光滑式耐油橡胶石棉垫片耐油橡胶石棉板4.0200光滑式 （凹凸式）1）缠绕式垫片 2）波形铁包石棉垫片0.8（15）钢带、石棉带、马口铁、石棉板2.542014502.54451600缠绕式合金垫片0Cr13（Cr13）或2Cr13合金钢带、石棉带6.416.0450梯形槽式 （椭圆槽式）1）椭圆形截面钢垫圈 2）八角形截面合金钢垫圈08（10钢）451600蒸汽10.2 2.54250 251600光滑式 （凹凸式）1）缠绕式垫片 2）波形铁包石棉垫片1Cr18Ni9（1Cr18Ni9Ti）合金钢10.0450梯形槽式 （椭圆槽式）1）椭圆截面钢垫圈 2）八角形截面钢垫圈08（15）钢带、石棉带、马口铁、石棉板水6.416.010008（10）钢盐水1.660光滑式橡胶垫片橡胶板150橡胶石棉垫片中压橡胶石棉板气态氨、液态氨2.5150凹凸式压缩空气、空气、惰性气体1.6200光滑式98%硫酸（质量分数） 35%盐酸（质量分数）1.690光滑式液碱1.660光滑式1）橡胶石棉垫片 2）橡胶垫片中压橡胶石棉板、橡胶板表29.3-17 橡胶石棉板厚度及适应范围种类厚度mm适用范围种类厚度mm适用范围XB2001，1.5，2，2.5，3，3.5，4，4.5，5，5.5，6200，1.5MPaXB4501，1.5，2，2.5，3450，6MPaXB350350，4MPa耐油1，1.2，1.5，2，2.5，3用于煤田、汽油等表29.3-18为凸面型球墨铸铁管法兰用石棉橡胶垫片。表29.3-19为凸面型球墨铸铁管法兰用石棉橡胶垫片内径和外径的极限偏差。表29.3-20为凸面型钢制管法兰和石棉橡胶垫片。表29.3-21为凹凸面型和榫槽面型钢制管法兰用石棉橡胶垫片。表29.3-22为钢制法兰用缠绕式垫片。表29.3-23为带外环型缠绕式垫片。表29.3-24为带内外环型缠绕式垫片。表29.3-18 凸面型球墨铸铁管法兰用石棉橡胶垫片（摘自GB/T12387-1990） （mm）公称通 径DN垫片内径d1公称压力PN/MPa垫片厚度t1.01.62.02.54.05.0垫片内径D02534按PN4.0MPa按PN4.0MPa65.5按PN4.0MPa7171.01.53324375.08280.5404984.59294.55061102.5107109.06577121.5127129.08089134.5142148.5100115162162172.5168180.01251741192192196.0194215.0150169218218221.5224250.0200220273273278.5284290306.0250273328329338.0340352360.5300324373384408.0400417421.0350356438444449.0457474481.5400407489495513.0514546538.5450458539555548.0564571595.5500508594617605.624628653.0600610695734716.5731747774.0700712810804833800813917911942900915101710111042100010161124112811541200122013411342136414001420154815421578160016201772176417981800182019721964200020002020218221682230注：垫片材料为XB450、XB350、XB200、NY300（石棉橡胶板标准GB3985）。 表29.3-19凸面型球墨铸铁管法兰用石棉橡胶垫片内径和外径的极限偏差（摘自GB/T12387-1990）（mm）公称通径DN垫片内径(d1)极限偏差垫片外径(d0)极限偏差400.50.850800.81.21002001.21.22506002.02.07009003.03.0100020004.04.0表29.3-20 凸面型钢制管法兰用石棉橡胶垫片（摘自GB/126.3-1988）（mm） 公称通 径DN垫片内径d1公称压力PN/MPa垫片厚度t0.250.61.02.02.54.05.0垫片内径D01018按PN 0.6MPa39按PN 4.0MPa按PN 4.0MPa按PN 4.0MPa46-1.5315224446.55152.520275456.06164.525346465.57171.032437675.08280.540498684.59294.5506196102.5107109.06577116121.5127129.08089132134.5142148.5100115152162162172.5按PN 4.0MPa168180.0125141182192192196.0194215.0150169207213213221.5224250.0200220262273273278.5284290306.5250273317328329338.0340352360.5300324373378384408.0400417421.0350356423438444449.0457474484.5400407473489495513.0514546538.5450458528539555548.0564571595.5500508578594617605.0624628653.0600610679695734716.5731774774.070071278481080483380081389091791194290091599010171011104210001016109011241128115412001220129013071341134213641400420014901504154815421578160016201700172417721764179818001820190019311972196420002000202021002138218221682230表29.3-21 凹凸面型钢制管法兰用石棉橡胶垫片（摘自GB/T9126.3-1988）榫槽面型钢制管法兰用石棉橡胶垫片（摘自GB/T9126.4-1988）（mm） 公称通 径DN凹凸面法兰用（GB9126.3-1988）榫槽面法兰用（GB9126.4-1988）垫片内径d1公称压力PN/MPa垫片厚度t公称压力PN/MPa垫片厚度t1.62.54.05.01.6 2.5 4.05.01.62.54.05.0垫片内径D0垫片内径d1垫片内径D01018按PN 4.0 MPa按PN 4.0 MPa340.8 324按PN 4.0 MPa按PN 4.0 MPa340.83152239352925.53935202750433633.55043253457514338575132436563.55147.56563.54049757361547573506187927373879265771091059585.51091058089120127106108120127100115149157129132149157125141175186155160.5175186150169203216183190.5203216200220259270239238259270250273312324292286312324300324363381343343363381350356421413395374.5421413400407473470447425.5473470450458523533497489523533500508575584549533.5575584600610675692649641.5675692700712按PN 2.5 MPa7771.5 3751按PN 2.5 MPa77780081388285688290091598796198710001016109110611091表29.3-22 钢制管法兰用缠绕式垫片（摘自GB/T4622.2-1993）（mm） 公称通 径DNa）基本型b）带内环型公称压力PN/MPa公称压力PN/MPaT1T2.5，4.05.0，10.0，15.0，25.02.5，4.05.0，10.0，15.0，25.0D2minD3maxTD2minD3maxTD1minD2maxD3maxD1minD2maxD3max104.51523.636.42 及 33.2及4.51524.5361927.640.414.318.732.42032.5442433.647.420.62540.12537523040.655.42731.4483246.564.53949.666.434.944.160.94053744555.672.441.350.470.45072935667.686.452.466.386.16084.51067283.6103.463.57998.9801071288496.6117.477.894.9121.1100128.5149.53.2131158.5108122.6144.4103120.3149.6125154.5175.5159.5187133147.6170.4128.5147.2178.4150182.5203.5189.5217160176.6200.4154174.2210200238.5259.5237271209228.6255.4203.2225263.9250291.5312.5285325262282.6310.1254280.6317.93 及 54.5及6.5300342.5363.5342382311331.6360.1354.2333375.1350394.5421.5373.5414355374.6405.4303.2364.7406.8400445.5473.5424.5471406425.6458.4342.5415.5464450496.5523.5488534.5452476.6512.4444.5469.5527.5500548.5575.5532.5585.5508527.6566.4495.3520.3578.3600648.5675.5640.5693.5610634.6675.4595.9625.1686.2700750.5777.54.5710734778.5800855.5882.5811835879.5900960.5987.5909933980.510001060.51093.5表29.3-23 带外环型缠绕式垫片公称通 径DN公称压力PN/MPaT1T2.02.5 4.02.54.05.0 10.0 15.0 25.05.010.015.025.0D2minD2maxD4maxD2minD3maxD4maxD4maxD2maxD2maxD4maxD4maxD4maxD4max10-23.636.448按PN2.5MPa-按PN5.0MPa-按PN15 MPa2 及 33.2及4.51518.732.446.527.640.45318.732.152.562.52026.640.156.033.67.46325.040.064.569.02532.948.065.540.655.47331.448.971.077.53245.660.975.049.666.48444.160.580.587.04053.670.484.555.672.49450.470.194.597.05069.586.1102.567.686.410966.386.9109.0141.06582.298.9121.583.6103.412979.098.9129.0163.580101.2121.1134.596.6117.414494.9121.1148.5166.5173.0100126.6149.6172.5122.6144.1170120.3149.6180.0192205.0208.5125153.6178.4196.0147.6170.1196147.2178.5215.0240246.5253.0150180.6210.0221.5176.6200.4226174.2210.0250.0265287.5281.5200231.4263.9278.5228.6255.4286293225.0263.9306.0319357.5351.5250286.9317.9338.0282.6310.4343355280.6317.9360.5399434.0434.53 及 54.5及6.5300269.3375.1408.0331.6360.4403420333.0375.1421.0456497.5519.5350371.1406.8449.0374.6405.4460477364.7406.8484.5491520.0579.0400421.5464.0513.0425.6458.4517549415.5464.0538.5564574.0641.0450475.9527.5548.0476.6512.4567574469.5527.5595.5612638.0702.5500526.7578.3605.0527.6566.4627631520.3578.3653.0682697.5756.0600631.4686.2716.5634.6675.4734750625.1686.2774.0790837.5900.5700-734.0778.5836800835.0879.5945900933.0980.51045表29.3-24 带内外环型缠绕式垫片公称通径PN公称压力PN/MPaT1T2.02.5、4.02.54.05.0、10.0、15.0、25.05.010.015.025.0D1minD2minD3maxD4maxD1minD2minD3maxD4maxD4maxD1minD2minD3maxD4maxD4maxD4maxD4max101523.636.448按PN2.5 /MPa按PN15 /MPa按PN15 /MPa2和33.2和4.51514.318.732.446.51927.640.45314.318.732.452.562.52020.626.640.1562433.647.46320.62540.164.569252732.94865.53040.655.4732731.5487177.53234.945.660.9753949.666.48434.944.160.980.5874041.353.670.484.54555.672.49441.350.470.494.5975052.469.586.1102.55667.686.410952.466.386.1109141.56563.582.298.9121.57283.6103.412963.57998.9129163.58077.8101.2121.1134.58596.611