密封墊的選用.doc

密封墊的選用密封墊的選用原則是：對(duì)于要求不高的場(chǎng)合，可憑經(jīng)驗(yàn)來(lái)選取，不合適時(shí)再更換。但對(duì)那些要求嚴(yán)格的場(chǎng)合，例如易爆、劇毒和可燃性氣體以及強(qiáng)腐蝕的液體設(shè)備、反應(yīng)罐和輸送管道系統(tǒng)等，則應(yīng)根據(jù)工作壓力、工作溫度、密封介質(zhì)的腐蝕性及結(jié)合密封面的形式來(lái)選用。一般來(lái)講，在常溫低壓時(shí)，選用非金屬軟密封墊；中壓高溫時(shí)，選用非金屬與金屬組合密封墊或金屬密封墊；在溫度、壓力有較大波動(dòng)時(shí)，選用彈性好的或自緊式密封墊；在低溫、腐蝕性介質(zhì)或真空條件下應(yīng)考慮密封墊的特殊性能。這里特別需要說(shuō)明的是法蘭情況對(duì)墊片選擇的影響。（1）法蘭形式的影響法蘭形式不同，要求使用的墊片也不同。光滑面法蘭一般只用于低壓，配軟質(zhì)的薄密封墊；在高壓下，如果法蘭的強(qiáng)度足夠，也可以用光滑面法蘭，但應(yīng)該用厚軟質(zhì)墊，或者用帶內(nèi)加強(qiáng)環(huán)或外加強(qiáng)環(huán)的纏繞密封墊。在這種場(chǎng)合，金屬墊片也不適用，因?yàn)檫@時(shí)要求的壓緊力過(guò)大，導(dǎo)致螺栓較大的變形，使法蘭不易封嚴(yán)。如果要用金屬墊片，則應(yīng)將光滑面縮小，使其與墊片的接觸面積減小。這樣，在螺栓張力相同的情況下，縮小后的窄光滑面的壓緊應(yīng)力就會(huì)增大。（2）法蘭表面粗糙度的影響法蘭表面粗糙度對(duì)密封效果影響很大，特別是當(dāng)采用非軟質(zhì)墊片時(shí)，密封表面粗糙度是造成泄漏的主要原因之一。例如，車削法蘭面的刀紋是螺旋線，使用金屬墊片時(shí)，如果粗糙度值較大，墊片就不能堵死刀紋所形成的這條螺旋槽，在壓力作用下，介質(zhì)就會(huì)順著這條溝槽泄漏出來(lái)。軟質(zhì)密封墊對(duì)法蘭面的光潔程度要求低得多。這是因?yàn)樗菀鬃冃?，能夠堵死加工刀紋，從而防止了泄漏。對(duì)軟質(zhì)墊片，法蘭而過(guò)于光滑反而不利，因?yàn)榇藭r(shí)發(fā)生界面泄漏的阻力變小了。所以，墊片不同，所要求的法蘭面的粗糙度也不相同。表29.3-15列出了各種密封墊所要求的法蘭表面粗糙度的經(jīng)驗(yàn)數(shù)據(jù)。（3）法蘭與墊片的硬度差使用墊片的目的在于使墊片產(chǎn)生彈性或塑性變形以填滿法蘭面微小凸凹不平，阻止泄漏發(fā)生。因而應(yīng)使墊片材料的硬度低于法蘭材料的硬度，二者之間相差越大，實(shí)現(xiàn)密封就越容易。當(dāng)使用金屬墊片時(shí)，為了保證實(shí)現(xiàn)密封，應(yīng)盡可能選用較軟的材料，使金屬墊片的硬度比法蘭硬度低40HB以上為宜。表29.3-16為石油部墊片選用標(biāo)準(zhǔn)。表29.3-17為橡膠石棉板厚度及適用范圍。 表29.3-15 法蘭密封而的表面粗糙度墊片類型墊片名稱表面粗糙度備注金屬密封墊環(huán)形墊片0.8自緊式密封墊希望表面越光越好鋸齒形墊片1.6半金屬密封墊金屬包墊片1.6纏繞墊片12.5纏繞墊片3.2氣體密封時(shí)石棉橡膠板12.5石棉布密封墊25聚四氟乙烯密封墊聚四氟乙烯板墊片12.5聚四氟乙烯包墊片12.5橡膠板25有機(jī)物密封墊油封25皮革密封墊25紙墊25表29.3-16 石油部墊片選用標(biāo)準(zhǔn) 介質(zhì)法蘭公稱壓力/MPa介質(zhì)溫度/法蘭密封面形式選用墊片名稱墊片材料油氣、油品、液化氣、氫氣、硫化催化劑（丙烷、丙酮、苯、酚、糠醛、異丙醇）、小于25%的尿素（質(zhì)量分?jǐn)?shù)）1.6200光滑式耐油橡膠石棉墊片耐油橡膠石棉板1.6201300光滑式纏繞式墊片08（15）鋼帶、石棉帶2.5200光滑式耐油橡膠石棉墊片耐油橡膠石棉板4.0200光滑式 （凹凸式）1）纏繞式墊片 2）波形鐵包石棉墊片0.8（15）鋼帶、石棉帶、馬口鐵、石棉板2.542014502.54451600纏繞式合金墊片0Cr13（Cr13）或2Cr13合金鋼帶、石棉帶6.416.0450梯形槽式 （橢圓槽式）1）橢圓形截面鋼墊圈 2）八角形截面合金鋼墊圈08（10鋼）451600蒸汽10.2 2.54250 251600光滑式 （凹凸式）1）纏繞式墊片 2）波形鐵包石棉墊片1Cr18Ni9（1Cr18Ni9Ti）合金鋼10.0450梯形槽式 （橢圓槽式）1）橢圓截面鋼墊圈 2）八角形截面鋼墊圈08（15）鋼帶、石棉帶、馬口鐵、石棉板水6.416.010008（10）鋼鹽水1.660光滑式橡膠墊片橡膠板150橡膠石棉墊片中壓橡膠石棉板氣態(tài)氨、液態(tài)氨2.5150凹凸式壓縮空氣、空氣、惰性氣體1.6200光滑式98%硫酸（質(zhì)量分?jǐn)?shù)） 35%鹽酸（質(zhì)量分?jǐn)?shù)）1.690光滑式液堿1.660光滑式1）橡膠石棉墊片 2）橡膠墊片中壓橡膠石棉板、橡膠板表29.3-17 橡膠石棉板厚度及適應(yīng)范圍種類厚度mm適用范圍種類厚度mm適用范圍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為凸面型球墨鑄鐵管法蘭用石棉橡膠墊片。表29.3-19為凸面型球墨鑄鐵管法蘭用石棉橡膠墊片內(nèi)徑和外徑的極限偏差。表29.3-20為凸面型鋼制管法蘭和石棉橡膠墊片。表29.3-21為凹凸面型和榫槽面型鋼制管法蘭用石棉橡膠墊片。表29.3-22為鋼制法蘭用纏繞式墊片。表29.3-23為帶外環(huán)型纏繞式墊片。表29.3-24為帶內(nèi)外環(huán)型纏繞式墊片。表29.3-18 凸面型球墨鑄鐵管法蘭用石棉橡膠墊片（摘自GB/T12387-1990） （mm）公稱通 徑DN墊片內(nèi)徑d1公稱壓力PN/MPa墊片厚度t1.01.62.02.54.05.0墊片內(nèi)徑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：墊片材料為XB450、XB350、XB200、NY300（石棉橡膠板標(biāo)準(zhǔn)GB3985）。 表29.3-19凸面型球墨鑄鐵管法蘭用石棉橡膠墊片內(nèi)徑和外徑的極限偏差（摘自GB/T12387-1990）（mm）公稱通徑DN墊片內(nèi)徑(d1)極限偏差墊片外徑(d0)極限偏差400.50.850800.81.21002001.21.22506002.02.07009003.03.0100020004.04.0表29.3-20 凸面型鋼制管法蘭用石棉橡膠墊片（摘自GB/126.3-1988）（mm） 公稱通 徑DN墊片內(nèi)徑d1公稱壓力PN/MPa墊片厚度t0.250.61.02.02.54.05.0墊片內(nèi)徑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 凹凸面型鋼制管法蘭用石棉橡膠墊片（摘自GB/T9126.3-1988）榫槽面型鋼制管法蘭用石棉橡膠墊片（摘自GB/T9126.4-1988）（mm） 公稱通 徑DN凹凸面法蘭用（GB9126.3-1988）榫槽面法蘭用（GB9126.4-1988）墊片內(nèi)徑d1公稱壓力PN/MPa墊片厚度t公稱壓力PN/MPa墊片厚度t1.62.54.05.01.6 2.5 4.05.01.62.54.05.0墊片內(nèi)徑D0墊片內(nèi)徑d1墊片內(nèi)徑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 鋼制管法蘭用纏繞式墊片（摘自GB/T4622.2-1993）（mm） 公稱通 徑DNa）基本型b）帶內(nèi)環(huán)型公稱壓力PN/MPa公稱壓力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 帶外環(huán)型纏繞式墊片公稱通 徑DN公稱壓力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 帶內(nèi)外環(huán)型纏繞式墊片公稱通徑PN公稱壓力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