管道焊接過(guò)程中克服磁偏吹的方法 克服電弧磁偏吹

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PipeweldingprocessovercomearcblowmethodXuTieHengFanYongMing(Chinapetroleumengineeringbranch,kindlyfirstHebelangfang065000)

Abstract:intheoilandgaspipelinesintheconstructionprocessofwelding,oftenencounterarcpartialblowphenomenon.Somearcpartialblowcausesaredifficulttobedetermined,andtheseriousinfluencetheweldingprocessofformingandwelding,leadtoweldingflaws.Forthisanalysisofpetroleumpipelineweldingarcblowintheconstructionprocessoftheinfluenceonthequalityofwelding,andconnectingwiththepipeweldingconstructionexperienceofseveralcaneffectivelyeliminateandreducearcblowmethod.

Keywords:pipelineconstruction;Welding;Arcblow;degaussing

preface

Inoilandgaspipelinesintheconstructionprocessofwelding,oftenencounterarcpartialblowphenomenon.Usuallybyreplacingweldingrods,adjustweldingarcAngle,downtheheight,theadjustmentgroundposition,rearrangeequipment,suchasweldingcaneliminateorreduce;Buttherearealsosomearcblowphenomenon,andthereasonisnotveryclear,inafewkilometers,afewtensofkilometerslongpipelineweldingconstructionprocesshasalwaysbeenthere,theseriousinfluencepipeweldingquality[1].

AnaturalgaspipelineconstructioninChinaweldingduringanalotofarcblowphenomenon,oftheweldingconstructionqualityhasseriouslyaffected.Thecausesofthearcblowisnotveryclear,pendingfurtheranalysis,effectivesolutionsneedfurtherinvestigation.

1arcblowtotheinfluenceofthewelding

Inthefieldofweldingtechnologyhaschangedtheelectricarcweldingarcshape,themothermaterialinfluencemeltingandweldforming;Throughtheelectromagneticstirringrole,changetheweldingpoolintheprocessofliquidmetalcrystallinemasstransferandheattransferprocess,whichchangesthecrystallizationofgrainsizeofthemethod,themechanicsperformanceofthewelddecreasedsignificantly,produceporosity,incompletefusion,crackweldingdefects.

1.1tothearcandtheinfluenceofthepool

Weldingarcisacontinuousgasdischargephenomenon,plasma.Usually,inallkindsofarcforce,undertheactionofarcweldingisconeshape.But,inadditionalmagneticfieldundertheroleofarcshapechangegreatly,whichproducethearcblowphenomenon.Becausearcshapeandmetalmotionstatechangesthatleadtoweldingpoolchangeshape.Poolbytheliquidmetaldiskblowoffunction,rotatingaroundtheweldingpool.Moltenpoolfront-endliquidmetalalongthesideofthepooltoflow,thecorrespondingmoltenpooltailliquidmetalintheothersideoftheforwardflow.Becausethemoltenpoolfront-endliquidmetaltothehightemperature,flowinprocessmakesidethanthefusion,fusionanothersidethansmall,causeweldingpooloftemperaturefieldofasymmetryandappearanceshapemoltenpoolofasymmetry.

1.2totheorganizationandtheinfluenceontheperformanceoftheweld

Accordingtothesolidificationtheory,grainsizeandmorphologyoforganizationbythenucleationrateandsubcoolinginfluence.Foracertainingredientsofalloy,itsinherentcausecompositionundercoolingsolutetheenrichmentlayerbytheliquidtemperaturegradientwidthandthecoolingspeedtwofactors.Usually,theweldingjointorganizationforthecellularcrystalorcellularcrystalbranches.

Whenamagneticfieldeffect,becausethepooloftheasymmetryofthetemperaturefield,makeweldsonbothsidesoftheliquidtemperaturegradientGandthecoolingspeedRarechanging,soonbothsidesofweldbeadsoluteunevendistribution.Thedistributionofthesolutedifferent,causeonbothsidesofweldbeadheterogeneousnuclearparticleconcentrationformdiffer,nucleationratedifferent;Leadtodifferentdegreescompositionundercooling,soinweldingseamorganizationonbothsidesofthewordsize,shapemarkedlydifferent,leadtoweldthemechanicalpropertiesoftheseriousdecline[2].

1.3totheinfluenceoftheweldingdefects

Arcblowinarcburninginstability,addinarc,thepowerofthecolumnisnotstable,itisshowntransitionirregular,leadingtotheweldpoolirregular,causecontinuousorintermittentbiteedge,rootinnotweldfully,rootfusiondefectsuchasbad.Theexistenceofthearcblowunderminedarcaroundtheprotectiveatmosphere,makeeasypoolminglingwiththeharmfulgassuchasair,causingporosity,slagdefectsuchas[3].

2arcblowthereasonsoftheanalysis

2.1falsearcblowphenomenon

Duetothesteelpipeinthewildenvironmentlong-termsunexposure,thewindblowsonthesteeltubetoproducestaticcharge,andthesteelpipecoatingsintheearthandsteelpipeplayedtheinsulationbetweentheeffect,makesteeltubeonalargeamountofstaticchargeenrichment.Inthemouth,electrostaticinductionroleinsteel,causeweldsproduceelectrostaticfieldposition,asshowninfigure1b,asshownbytheroleofthearcelectrostaticfieldfromtheaxisofweldingrod,andproducedthepartialblowphenomenon.Becausethisiscausedbytheelectrostaticfield,socalledfalsearcblow.

2.2itselfofthemagneticfieldofthecurrenttoproducecausearcblow

Weldingarcarcbeamisacertaindegreeofionizationofgas,tocertaindirectionformcurrentinarcaroundproduceamagneticfield.Forsomereasonthatarcitselfthemagneticfieldsproducedbythedistributionuniformitywasbroken,thearcduetounevendeviatingfromtheelectrodeforcearoundtheaxisofthedirection,whichproducethephenomenonofarcblow(4,5),asshowninfigure1cbelow.

2.3pipecausedbyresidualmagnetismarcblow

Pipelinesteelforhardmagneticmaterials,itscharacteristiciseasytokeepsomemagneticaftermagnetization,theconstructionworkenvironmentmagneticfield,andconstructionprocessofmagneticmaterialandmetwillallowweldingresidualmagnetism,sothatthebackoftheweldingprocessproducesarcblow.IfHanKouremanentoveracertainvalue,arcblowphenomenonwillveryserious,can"tevenweldingprocess.

2.4theeffectsofenvironmentalfactors

Longdistancepipelineweldingconstructionsiteinthewildaremostlyenvironment,alongthepipelineconstructionsitetheextensiondirectionchanges,sothemagneticfieldaroundconstructionsitesfromarcblownotsallowtoignore.Usually,thisbecausethemagneticfieldaroundconstructionsitesfromarcblowisnotveryserious,butbecauseofthecausecauseddifficulttojudge,oftendifficulttoeliminate,isoftenalongpipeweldingconstructionprocesshasalwaysbeenthere,weldingprocesscausemajorproblems.

3solvearcblowmethod

3.1groundingmethod

Theweldingwhenconstruction,willtheweldingpoweralwaysconnecttoweldingofgroove,andagainfrommainlandlineconnectionpointweldinggroovesplacereceivesametallineeventotheearth,asshowninfigure2shows.Thismethodforgroundpositionnotcorrect,groovecutcausessuchasstaticchargecausefalsearcblowhavebettereffect.

3.2adjustweldingdipAngle,shortarcweldingmethod,segmentationmethodbackwelding

InoperationonappropriateadjustmentstotheelectrodeAngle,theelectrodestoarcblowdirectiontilt,orbyusingweldingmethodandshortbackarcweldingmethodcaneffectivelyovercomearcblow.

3.3heating

Weldingoftheresidualmagnetismonthemainisarrangedinorderofmagneticatomsdependenceandcause.Forthedisordersofweldingmagneticw.toreduceorpreventarrangedthepurposeofarcblow,canexistonabuttweldendstothepartsoftheresidualmagnetism,localheating,generalheatingtemperatureof250~300℃.Theproductionuseinadditiontogoodeffect.

3.4cablewindingmethod

Accordingtothearcblowjudgethedirectionofthemagneticfielddirection,willbeinchargeofthecentralpartoftheweldingtorchcableofthemouthRenYiDuanwindingfewlapsinthecoilelectricityatthesametimewelding.

3.5plustheferromagneticmaterials"method

Intheweldsandnearferromagneticmaterials,aferromagneticmaterialsside,becausetheferromagneticmaterialspermeability,mostmadeofferromagneticmaterialfieldlinesthrough,sothatthissideofspacefieldlinesgoeslean,willreducetheinfluenceofelectricarc.Soputthemagneticfieldoftheferromagneticmaterialsproducedsymmetrical,trytomakearcofferromagneticmaterialdistributionaroundeven,sothatthefieldofelectricarcreducetheinfluenceofevendisappear.

summary

(1)longpipelineconstructioninweldingoftenadjustAngleortheweldingwithsubsectionweldingmethodtoreturntoreduceo