管台焊接程序课件

管台焊接程序管台焊接程序管台焊接程序ASIAConstructionEngineeringTrainingConferenceFY2007

ASIACONSTRUCTION:

BUILDINGAIRPRODUCTSFUTURESeptember18to22,2006管台焊接程序管台焊接程序管台焊接程序ASIAConstru1管台焊接程序课件管台焊接程序课件管台焊接程序课件管台焊接程序课件WeldingsetupReadytoweld:Everyfittingisshapedtofitthepipeandself-aligning

焊接准备：每一个管台都被加工成适合管道的形状，以便对正Theoutletismachine-beveledforquickeasybutt-weldingofbranchpipe

forshoporfieldfabrication

管台焊接处被加工成坡口，以适合车间或现场支管快速对焊WeldingsetupReadytoweld:EWeldingsetupLayout:thetemplateisinsideofthefitting

Cuthole:theholeintherunpipeonreducingsizescanbecutouteitherbeforeorafterthefittingisweldedon.Theholecanbecutwithdrilloraholesaw.Weldingthefittingtorunpippriortocuttingtheholehelpspreventdistortionoftherunpipe

andcanbedonegenerallyonoutletsizeovertwoinches放置模板于管台内部开孔：变径管台在主观上的开孔既可以在焊接前也可在焊接后再开。可以用钻孔，也可用孔据开孔。先在主管上焊管台后开孔可以防止主管扭曲，一般适用大于2英寸的管台。WeldingsetupLayout:thetemWeldingsetupSpaceforwelding:Theweldoletisraisedofftherunpipetoestablishproperweldgapbyplacingspacers,e.g.weldingrodsunderthefitting.Thisprovidesauniformweldinggapbetweenthecurvatureoftherunandbaseoffitting

焊接间隙：管台焊接前要保证与主管的焊接间隙，例如放一根焊条在管台和主管之间。这样可以保证焊接根部间隙均匀。WeldingsetupSpaceforweldinWeldingsetupTackweld:Thebasejointistackwelded,preferablyatfourpoints,eachhalfwaybetweenthecrotchandskirtsectionsoffitting.Thespacersaretheremoved点焊：根部需要点焊，建议4点，分布在管台的肩部，同时移掉间隙物。WeldingsetupTackweld:ThebWeldingsequenceLongitudinalsection:Widebasesorfootingsatcrotchsectiondistributeinternalandexternalstresses.Gradualchangesofsectioneliminatestressconcentration.Funnelshapedopeningprovidesimprovedflowdirection纵断面：分叉处存在内外应力，截面渐变消除了应力集中。漏斗状开口有利于流体流动。WeldingsequenceLongitudinalsWeldingsequenceTransversesection:Notetheblendingoftheskirtsectionweldolettotherunpipetoavoidabruptchangeinintersection.Throatofweldatthispointisdesignatedbytheweldingbevel.

横断面：管台裙叉处和主管处的坡口过渡可以避免交叉点的急剧变化，

WeldingsequenceTransversesecWeldingsequenceStringerbead:Thestringerbeadisappliedcompletelyaroundthebaseofthefitting.Theestablishedweldgapassuresfullpenetration

线型焊道：线型焊道紧紧环绕管台焊接，焊道间隙可以保证完全焊透。

WeldingsequenceStringerbead:WeldingsequenceReinforcingbeads:Reinforcingweldsshouldbemadeatthecrotchbevelareasofthefittingtoprovidemaximumweldatthecrotchtaperingtominimumattheskirt.Particularareshouldbetakentoweldonlythebevelportionofthefitting.Thiseliminatestheunnecessaryuseofcontinuouspassesandpreventstheerroneouspracticeofweldinguptotheribontheskirtportionoffitting.Acontinuouscoverbeadshouldbeaddedtofillthebevelandprovideasmoothtaperedweld.加强焊道：加强焊道应该在管台分叉处坡口进行最大焊接，而在裙尖处进行最小焊接，特别是焊接坡口部分。这就是说可以减少一些连续焊接，防止裙尖处的过渡焊接。连续的焊接应填满坡口，然后渐缩到裙尖处。WeldingsequenceReinforcingbeWeldingsequenceWeldingsequenceEspeciallynoteWhenusingthechartsinMSSSP-97whenthepipewallscheduleactuallybeingusedisheavierthanlistedinthechartyouneedtousethenexthigherchartdimensions.ThisisbasedononTable1andnote(a)wheresinceourrunpipescheduleisSch80(wallthickness=0.938")andnotXS(wallthickness=0.500")youneedtousetheSCH160classfittingsanddimensionswhichmeansweneedtouse

the

105mmdimension.PurchaseandInspectionmaterialsshouldknowthisprinciple.当用MSSSP-97查支管道壁厚时，表中壁厚应该采用高一级的尺寸。例如：当我们知道主管壁厚是Sch80，我们应该采用SCH160class的管台尺寸，见表。所以采购和检查时应知道这个道理。EspeciallynoteEspeciallynotesMultipleoutletheadersrequiringallfullsizeopeningsaresubjecttodistortionbecauseofthelargenumberofholesthathavetobecutincloseproximitytooneanother.Toeliminatethepossibilityofdistortionoccurringwhenusingweldoletsinthistypeofinstallationwerecommendthatastrapbeleftinthecenterofthehole,bycuttingouttwohalfmoonsection(asshowninsketch).Thisstrapactsasasupportuntilaftertheweldolethasbeeninstalledandisthencutout多管台的主管，需要开孔的话，由于相距太近，开孔焊接易引起变形。为减少扭曲变形我们推荐在孔中心预留一块不切割，

先切割2个半月状，然后焊接。而中心这一块可以防止焊接变形，等完全焊接完成，用曲线据切除最后这一块。EspeciallynotesMultipleoutleEspeciallynoteWeldoletweldingoftenoccurredissue:non-penetrationFor4"andabove,itcouldbeweldedatbothside,eventhereissomedifficultywithbackgougingandbackweldingButfor3"andblower,itisnotaccessiblewithbackgougingandbackwelding,thereasonis1)Thetorchsizeweldingatbacksideisimpossibleaccess,andsometimesthetorchcouldnotaccessthebevelwellatsomeangle.2)TheIDofweldoletandopeninginrunpipehassomedeviation.3)Thebevelcurveofweldoletdonotfitpipewell.Oncefoundnonpenetration,needtocuttingofftheweldolet,rewelditfromtherunpipetoachievepenetrationascouldaspossible.1~2mmnon-penetrationisacceptable.Ifmorethan2mmnon-penetration,backsideneedbewelded.

管台焊接常出现未焊透问题：大于等于4寸的管台，可以从内外两边焊，虽然有时内部清根焊接有点困难

3寸及3寸以下管台，内部无法清根和焊接的原因如下

1）焊把尺寸大不易接近内部，有时角度不好而未焊透

2）管台内经合开孔又偏差

3）管台坡口曲线与管道不匹配3寸及3寸以下管台一旦发现未焊透，需要割掉管台重新焊接或从主管道内部焊接。1~2mm未焊透可接受，大于2mm未焊透背面要焊接EspeciallynoteWeldoletweldinSitephoto

WeldoletreceiveandinspectionSitephoto

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