压力容器焊缝及其结构设计

来源：化拓教育网

　　　　　　　　　　　　　　　　　　化　工　机　械　　　　　　　　　　　　　　　1999年150

压力容器焊缝及其结构设计

朱连顺Ξ

(中国成都化学工程公司)

摘　要　压力容器破裂的主要原因是焊接质量低劣,指出了影响焊缝质量的因素,论述了

焊缝结构设计基础及焊缝设计应注意的问题。关键词　焊缝结构　焊缝裂纹　手工电弧焊　埋弧自动焊　　压力容器成形采用电焊,导致压力容器破坏的主要原因是焊缝质量低劣。根据国内外压力容器事故分析,因裂纹而导致事故占总事故的50%～%,英国因裂纹造成的事故占%,中国因裂纹造成的事故占50%(因焊缝裂纹造成的事故占37.5%)[1]。因此,提高压力容器焊接质量是确保压力容器安全运行的重要环节。本文就影响焊缝质量的因素及焊缝设计应注意的一些问题做了探讨。1　影响焊缝质量的因素1.1　设计因素

设计人员往往只注意焊条、焊丝、焊剂及对接

焊缝系数。设计院除特殊工况(疲劳、低温、大的

温度梯度、毒性极度危害介质等)对壳体焊缝作说明外,一般只画节点图或标注焊接结构序号,不作是否焊透或检验要求等说明。忽略了如何设计出接管与壳体焊缝形式、几何尺寸,对焊接工艺缺乏了解。

某氮肥厂氨合成塔图纸,对接焊缝的设计见图1a。合成塔外壳设计压力P=15.7MPa,T=200℃,󰂋1200mm×76mm(16+10×6)多层卷板。技术要求栏注明焊接材料J507,焊丝16MoSi焊剂250。

a.筒体对接焊简图　　　　　　　b.U、V形坡口双面手工　　　　　　c.U、V形坡口正面埋弧自动

电弧焊(环焊缝)　　焊背面手工电弧焊(环焊缝)

图1　筒体对接焊简图(焊接方法不同)

　　从图纸看,手工电弧焊和埋弧自动焊的坡口调:内筒A类焊缝全焊透,焊后做消除残余应力形式及尺寸一样,实际上,焊接工艺不同对坡口形热处理,外观检查合格后进行100%的RT或UT式和尺寸影响很大。当容器壁厚S≥76mm时,检验,外表面做机加工或修磨平滑;层板包扎前应正确的做法是U、V形坡口双面手工焊如图1b所清除铁锈、油污和影响贴合的杂物;下层包扎前将示,U、V形坡口正面埋弧自动焊背面手工电弧焊如图1c所示。另外,对多层包扎高压容器特别强

前一层C类焊缝磨平滑,各层C类焊缝均应错开;每层包扎按图样要求钻泄放孔等。焊接工艺

Ξ朱连顺,男,1942年8月生,高级工程师。四川省成都市,610041。

第26卷　第3期　　　　　　　　　　化　工　机　械　　　　　　　　　　　　　　　　　　151规程按图样要求和评定合格的焊接工艺制定。图纸的坡口应当合理准确。1.2　焊接坡口的形状和尺寸主要取决于材料和焊接工艺

焊接不同材料,焊缝坡口的形状和尺寸也有差异。如普通碳钢由于焊接热不敏感,可采用高线能焊接规范,坡口截面应当大些;焊镍、铬不锈钢时,坡口截面应当小些,因这种材料焊接热敏感,应采用低线能焊接,并且避免焊热的多次作用。

焊缝坡口的形状和尺寸与焊接方法有关。手工电弧焊由于熔深较浅,6mm以上的钢板就需开V形坡口;而埋弧自动焊具有深熔的特点,20mm以下的钢板可以不开坡口。又如手工电弧焊与气体保护焊相比,前者的开口角度较大些。这是因为手工电弧焊的焊条直径较粗,焊缝表面覆盖较厚的熔渣层,较大的坡口能使焊条伸入坡口底部,便于脱渣。气体保护焊焊缝表面无熔渣,焊丝直径较细,故可采用张角较小的坡口。熔化气体保护电弧焊的V形坡口一般为45～50°,而手工电弧焊V形坡口大于60°。另外,焊缝坡口形式和尺寸的选用,还与制造厂的加工能力有关,V、X形坡口用半自动切割机即可制备,其缺点是填充金属较多,焊接效率较低。U形坡口与V形坡口相比,坡口容积较小。U形坡口的侧面斜度取决于焊接方法,手工电弧焊和熔化极气体保护焊可取2～5°,埋弧焊5～10°范围内。1.3　自觉遵守焊接规范,提高焊工的焊接技术和知识水平1.4　制造厂应有全过程的质量保证体系

对焊工要求持证上岗,在规定部位打上焊工钢

印。焊材应保存在相对湿度不大于60%的库里。施工环境:风速对手工焊不大于10m/s;对气体保护焊不大于2m/s;相对湿度不大于90%,雨、雪天不施焊。焊接工艺按“压力容器焊接工艺评定”进行焊接工艺评定,焊接工艺规程应按图样要求和评定合格的焊接工艺制定。焊缝外观不允许有裂纹、夹渣、气孔、弧坑和熔渣等。焊前预热:施焊处100mm范围内预热15℃左右;焊件温度低于0℃时必须预热。质量保证体系的每个环节都有文字记录。2　焊缝结构设计2.1　焊缝结构设计基础

焊缝的设计是在等强度的基础上,即焊缝与相邻母材具有相同的强度。一般不需要使用大于规范图中所示的焊缝尺寸。2.2　焊缝结构设计2.2.1　焊缝坡口设计

坡口及间隙对焊缝质量有直接影响,因此,应提高坡口尺寸的精度。图纸上焊接接头的形式可采用序号、标准代号、节点图3种表示方法中任意一种,当采用前两种方式时,必须注明标准号和名称。

某设计院三类压力容器图纸上技术要求栏中:焊接材料J507,对接焊缝代号标准见节点图。但装配图中并未见对接焊缝详图,只在部件图中,有受压元件边缘加工图,如图2a所示。正确的做法是应在装配图中,分别画出环焊缝、纵焊缝详细节点图,如图2b、c所示。　　焊缝坡口尺寸不完整、不准确,制造厂按照图施工,故难以保证焊接质量。

a.坡口　　　　　　　　　　　b.环型焊缝　　　　　　　　　　　c.纵焊缝

图2　对接焊缝

　　　　　　　　　　　　　　　　　　化　工　机　械　　　　　　　　　　　　　　　1999年152

2.2.2　接管与筒体的焊接

美国ASME规范认为,接管设计应最大限度地降低应力集中。最安全的容器是各部分都具有最低的总应力(一次应力加应力集中等),而不是在一次薄膜应力上取最大的安全系数,不管局部应力集中。所以,有效降低应力集中值是设计接管与容器间焊缝时应特别重视的问题。

一部分设计人员对接管与筒体间焊缝不够重视(除接管直径大,做开孔补强计算外),大量的接管设计都不能遵循下面原则:

　　a.焊接接头的强度不低于母材标准规定的抗拉强度下限。

b.合理选择坡口角度、钝边高、根部间隙等结构尺寸,使之有利于坡口加工及焊透,以减少各种焊接时产生缺陷。

c.焊缝表示应完整、准确。当以标准代号标

图4　接管与筒体焊缝

3　结束语

　　压力容器的焊接质量是个系统工程,在我国

跨过设计和制造两个的体系,因此在抓设计质量的同时也要抓制造质量。设计者应学习了解制造、焊接方面的知识,以便根据不同材料、不同焊接工艺设计出合理的焊缝坡口形式。另外,要加强焊接质量保证体系,对焊工要求、焊接工艺规定、焊接材料保管、施焊环境、焊前预热及焊缝外观检查等方面必须有全过程的质量保证体系。

对不受外力的温度计、液面计、仪表、检查孔等接管与筒体焊接,应按实际情况规定可否允许部分焊透或填角焊等。

δ-pGB985288/3中H=的规定是否合理?

按此规定U、V形坡口两侧深度相等,只是多一种机加工形式。笔者认为改H=10±2mm为宜。因为这种坡口多用于厚壁筒体环焊缝,外侧U形坡口深度大,施工方便,省焊接金属;内侧V形坡口深度小,机加工简单,施工量小,结构合理。

参　考　文　献

1　钱逸等.压力容器安全技术基础.北京:中国劳动出版

志焊缝形式时,在引出线尾部分叉处应标注接头序

号、是否焊透、铲根要求、检验方法等,如图3所示。

图3　焊缝形式标注示例　　在同种工况下,接管的直径及受力不同,应选择不同焊缝结构。美国ASME规范应力分析篇提出,不受外载的接头、仪表接管、检查孔等可采用部分焊透或填角焊缝[2]。我国的压力容器焊接规范在这方面未有明确规定。某设计院的一类容器图纸,接管N1、N2、N3、N4、N5分别为250、50、200、25、20mm,接术要求:接管与筒体焊接见节点图(图4),这种焊缝结构对直径小的接管,尤其对󰂋25mm×3mm接管是很不合理的。因为筒体与接管壁厚相差4倍,填角焊缝高10mm,焊缝余高6mm,焊缝的金属量太多,使接管产生过热甚至焊穿。另外,从焊缝设计等强度理论,也不需要这种结构。

社,336

2　ASMEBoilerandPressureVesselCode.AnInternation2allyRecognizedCode,Section.Ⅷ.RuleforConstructionofPressureVessels.Division22AlternativeRules.ASMEBoilerandPressureVesselCommitteeSubcommitteeonPressureVessels.1995.(ADD26)AD-621

(收稿日期:1998212214)

第26卷　第3期　　　　　　　　　　化　工　机　械　　　　　　　　　　　　　　　　　　185

ABSTRACTS

　　Researchesonenergyconsumptionmechanismandenergy2savingprinciplesofhydrocyclones.Ⅷ.OptimumEnergy2SavingPrinciples.ChuLiangyin,ChenWenmei,LiXiaozhong,LiuPeiklun(SichuanUniversity,Chengdu,Sichuan,China)………

……………………………………………………(125)Astudywasmadeofthematchingoptimumofthesavingenergyandthereinforcedseparationperformanceofhydrocy2clones.Theresultsshowthatthereductionofenergyconsump2tionandthereinforcementofseparationperformanceofhydrocy2cloneswereingoodagreement,andanoptimumenergy2savingprinciplewasproposedofconsideringboththesavingenergyandthereinforcedseparationperformance,theinfluencelawsofen2ergyconsumptioncoefficientsandtheoperationcostcriterionwerestudied,thebasicaldataofanoptimumstructureassemblyweresystematicallygivenwhenhydrocyclonestookvariouspro2cessindexesasobjectivefunctions,andthedesignguideofopti2mumsavingenergyofthehydrocyclonesoperatinginvariouspro2cessworkingconditionswasprovided.

KeyWords:Hydrocyclone,EnergyConsumption,SavingEnergy,SeparationPerformance,Optimum

Influencesofaxisymmetricalinletwithrevolvingpassagesontheseparationcharacteristicsofcycloneseparators.DiaoYongfa(Xi′anJiaotongUniversity,Xi′anShaanxi,China)JinWeiwei(Xi′anUniversityofArchitect&Technology,Xi′an,Shaanxi,China)ShenHenggenXuJinyuan(Xi′anJiaotongUni2versity,Xi′an,Shaanxi,China)…………………………(130)

Theinletofasingle2inletcycloneseparatorwasmadetheaxisymmetricalinletwitharevolvingpassage,i.e.thedouble2in2letpassagelengthswerethesameasthesingle2inletpassagelengthsforthenon2axisymmetricalgasflowinthesingle2inletcycloneseparators.Theinfluenceoftheaxisymmetricalinletwitharevolvingpassageontheseparationperformanceofcyclonesep2aratorswasanalysedinthefieldsoftheinletgasvolume,thedustconcentrationatinlet,theresistancelossofcycloneseparators.Thecalculationcomparisonofgradingseparatingefficiencyshowsthattheseparationperformanceofthenewtypecyclonesepara2torsisnotonlysuperabletothatofthesingle2inletcyclonesepa2rators,butalsotothatofStrairmandhigh2efficientcyclonesepa2rators.

KeyWords:CycloneSeparator,InletWithRevolvingPas2sage,Axisymmetry,SeparationCharacteristics,InfluenceResearchesontheweldingseamstressofpressurevesselsoftitanium.ChenJiguang(YueyangUniversity,Yueyang,Hunan,China)LiGangling(SouthChinaUniversityofTechnology,Guangzhou,Guangdong,China)………………………(133)

Thefailureofpressurevesselsoftitaniumwasproventobeoriganatingfromtheirweldingseamthroughtests,thestressofweldingseamswasstrongestatthe5～10mmlocationfromtheweldingseamroots,wasthe2.28～3.51timesofthebidirec2tionalintensificatedcalculatingvalueofthecylinders,andsomenewresearchthemesofstrengtheningtheweldingseamstrengthandloweringthestresspeakvalueofweldingseamswerepro2posed.

KeyWords:PressureVesselofTitanium,StressofWeldingSeam,WeldingSeamRoot

Influencesofthemagneticpolestructureonthesealper2formanceofmagneticfluid.HuoLiping,AnQi,CaiRenliang(EastChinaUniversityofScienceandTechnology,Shanghai,China)………………………………………………(136)

Theinfluencesofcompoundmodesandstagenumbersofmagneticpoles,ofmagneticfielddirectionofmagneticsource,and

ofsealclearanceinamagneticfluidsealapparatusonthesealperformancewerestudied.Theexperimentalresultsshowthatthesealperformanceofmagneticfluidbecamebetterwiththein2creaseofthestagenumbersandthereductionofsealclearance,andwasrelatedwiththecompoundformsofmagneticpolesandthemagneticfielddirection.

KeyWords:MagneticFluid,SealofMagneticFluid,SealPerformance

Applicationresearchesontherotarydiscdynamicmem2branefiltrationtechnologyforbacterium2enzymeseparationprocessinenzymepreparationproduction.WangXiaojing,SuWei(TianjinUniversity,Tianjin,China)YinXin(TianjinMaleableCastIronPlant,Tianjin,China)JinDingwu(TianjinU2niversity,Tianjin,China)………………………………(139)

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KeyWords:DynamicFiltrationMembrane,EnzymePrepa2ration,Bacterium2EnzymeSeparation

EffectsofretarderTBContheautomaticoxygenationofsulfite.XiongRongchun,WeiGang(BeijingUniversityofChemi2calTechnology,Beijing,China)ZhangXinmin(TheMinistryofScienceandTechnology,Beijing,China)ZhangXiaodong(BeijingUniversityofChemicalTechnology,Beijing,China)…………………………………………………………………(143)AstudywasmadeoftheeffectsofretarderTBContheau2tomaticoxygenationofsulfitethroughtests.Theresultsshowthatthereactionprimeroffreeradicalchain———copperioncanacceleratethereactionbetweensulfiteandoxygen,thefreeradicalabsorbent———retarderTBCcaninhibitthereactionbyeliminat2ingthefreeradicalgeneratedintheoxygenationprocessofsul2fite,thepH,alkalinity,andhardnessofwaterhavenoeffectsonthereaction.Thetestresultsprovideimportantidentificationforthefreeradicalmechanismofoxygenationofsulfite,andefficientmethodsofpreventingsulfitefailureinstorage.

KeyWords:Sulfite,RetarderTBC,FreeRadicalReaction,Initiator,RadicalAbsorbent

CalculationandanalysesoftheaxialthrustoftherotorinthehighpressurecylinderofaCO2centrifugalcompressorundertheconditionofvariousrotaryspeedsandflowrates.XiGuang,WangShangjin(Xi′anJiaotongUniversity,Xi′an,Shaanxi,Chi2na)……………………………………………………(147)

ThechangelawsoftheaxialthrustoftherotorinthehighpressurecylinderofaCO2centrifugalcompressorintheworkingconditionofvariousrotaryspeedsandflowrateswerestudied,theaccidentcauseofaxisdamageoftherotorinthehighpressurecylinderofaCO2centrifugalcompressorinthestartingprocesswasrevealedbasedonmeasuringtheperformancecurvesoftheimpellersoftherotor.Somemethodsofcontrollingtheaxialthrustandpreventingtheaxisdamagewereproposedforthecharacteristicsof520000t/aureaplantsinproduction.

KeyWords:CentrifugalCompressor,RotorinHighPressureCylinder,Non2UniformWorkingCondition,CalculationofAxialThrust

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　　　　　　　　　　　　　　　　　　化　工　机　械　　　　　　　　　　　　　　　1999年186

Itwasconcludedthatmostofthecrackcauseswerebecauseofthebadweldingquality,thefactorsaffectingweldingseamsqualitywereproposed,thedesignbasesofweldingseamstructureandthekeyproblemsinweldingseamdesignweredescribed.

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(weldingofcylinders.JiRundongLianyungangJuniorColledgeof

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KeyWords:Thin2WallCylinder,Butt2WeldingSeam,StressandDeformation

Applicationoffluoroplastics2graphiteplateheatexchang2ersintheproductionofaluminiumsol.WangShihong,YinXix2iang,MaZhongfu(LanzhouPetroleumProcessing&ChemicalComplex,Lanzhou,Gansu,China)YiGewen,LiuGang(Res.InstofChem.MachoftheMinistryofChem.Indu,Lanzhou,Gansu,China)………………………………………………(157)

Theselectionandapplicationoffluoroplastics2graphiteplateheatexchangersintheproductionofaluminiumsolwerepresent2ed.Theseexchangershaveadvantagesinapplicationcomparisonwithotherkindsofexchangers.Thehighcorrosionresistance,highefficientheatexchange,andsealgivetheseheatexchangersalongservicelife.

KeyWords:PlateHeatExchanger,Fluoroplastics,Graphite,Application,Corrosion

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………………………………………………………(159)Thecharacteristics,structure,designandmanufactureofmajorcomponentsoftheLHSY211.5Ndouble2spiralcone2shapemixerswerepresented,andtheassemblyandtest2runofthema2chineweredescribed.

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KeyWords:CirculatingAirCompressor,StuffingBox,StructureRetrofit

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………………………………………………………(168)Thestructurecharacteristics,reinforcedresults,suitableworkingconditions,andapplicationwereanalysedindetailofre2inforcedheatexchangersbasedonthereinforcedmechanismofthereinforcedheattransfer,atheoreticalbasiswasprovidedforthereinforcedtubeselection,andtheresearchdirectionofexist2ingreinforcedheattransferwasgiven.

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Reviewofthecalculatingmodelsofcirculatingflowofket2tle2shapedreboilers.HouMing,XuWeiqin,ShenZiqiu(DalianUniversityofTechnology,Dalian,Liaoning,China)……

………………………………………………………(171)Atheoreticalanalysiswasmadefortheshellsidecirculatingflowinakettle2shapedreboiler,thecirculatingmodelwasre2viewed,themethodofdeterminingthecirculatingflowwasde2scribed,thecalculatingmethodsofthetwophaseflowpressuredropandthevolumefractionoftheacrosstubebankswerecom2pared.

KeyWords:Kettle2ShapedReboiler,TwoPhaseFlow,Hor2izontalTubeBank

Aprimaryestimationmethodforpressurevesselsbasedonartificialneuralnetwork.YuShurong,LiErguo,JiaLi(GansuUniversityofTechnology,Lanzhou,Gansu,China)…

………………………………………………………(176)Aprimaryestimationofpressurevesselswasmadebyusingartificialneuralnetworkmethod,andtheresultwasingooda2greementwiththeresultbyusingtheCVDA284method,apri2marybasiswasestablishedfortheintelligentsafetyestimation(expertsystem)ofpressurevesselswithartificialneuralnetworkmethod.

KeyWords:PressureVessel,FailureEstiation,ArtificialNeuralNetwork

Chemicalsolutionsofcontrollingthescaleinrecirculatingcoolingwatersystems.ZhouBensheng(NanjingUniversityofChemicalTechnology,Nanjing,Jiangsu,China)………(179)

Fivechemicalsolutionsofcontrollingthescaleinrecirculat2ingcoolingwatersystems,i.e.scaleinhibitors,acidaddition,car2bondioxidemethod,ionexchangesoftening,limesoftening,weresimplydiscussed.

KeyWords:CoolingWater,ScaleControl,ChemicalSolu2tion

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