焊接轮廓用于疲劳改善Word格式.docx

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MethodsofFatigueBehaviorImprovement

by

WeldprofilingandNDEusedforCNOOCPanyu4-2/5-1Jackets

ByCharlieChinChanChong

ASQCCertifiedQualityEngineer,ASNTNDTLevelIIIJM1715,

MICorr,SenAWeldI,EuropeanWeldingInspector

NACESeniorCorrosionTechnologist.

ADiscussionontheMethodsofFatigueBehaviorImprovement

byweldprofilingforPanyu4-2/5-1Jackets

Synopsis:

ThispaperpresentsadiscussiononvariousmethodswhichContractormayusetoperformtheweldprofilingactivitiesonDesignerdesignatedfatiguesensitivejoints.

EvenintheabsenceofDesignerdesignation,theWeldingInspectorshouldensuretheweldprofilescomplywiththeAWSD1.1Table2.7requirementsLevelIIasaminimum,appliestopre-qualifiedTKYjointsforintermediateandheavysectionswherethecoderequiresdifferentlevelweldprofiling.

1.Introduction:

Forfatiguebehaviorimprovementbyweldprofiling,itisimportantthattheactivitiesarecarriedoutbythefabricatorincorrectmanners.Followingisawrite-upsummaryofAPI2AWSDandAWSD1.1requirementsandproposalsthatmayassistthefabricatorinachievingthisobjective.

2.Discussion.

2.1TheCodes.

AcceptableoffshorepracticesusuallycallforeitherAWSD1.1orAPI2AWSDrequirementsonweldprofiling.TheDesignershouldspecifytheapplicablecode.API2AWSDSection11.1.3dwastheapplicablesectioncalledbyDesigner.

2.1.1API2AWSDSection11.1.3d

ThesectionstatedthatwherecontrolledweldprofilinghasbeenconsideredtheweldsurfaceshouldmergessmoothlywiththeadjoiningbasemetalandapproximatestheconcaveprofileshowninFigure11.1.3eitherasweldorwithprofilegrinding.

Therequiredprofilecheckisbyaprofilediskwithdiameterequalorgreaterthanthebracethicknessandthenotchesrelativetothedesiredweldprofileareconsideredunacceptableifthereisa0.04 

in.（1mm）gapbetweenthediskofthespecifiedradiusandtheweld,eitheratthetoeoftheweldorbetweenpasses.

TheweldtoesshouldalsobeMPItestedtocheckforsurfaceandnearsurfacedefect.

2.1.2AWSD1.12.36.6.6

TheapplicableProject’sweldingcodeisAWSD1.1.ForT-,Y-,andK-connections,twolevelsoffatigueperformanceareprovidedforinTable2.7.LevelIandLevelII.

Dependingonthelimitingbranchmemberthickness,fourtypesofweldprofilerequirementsarespecified,namely

1.StandardflatweldprofileinconformancewithFigure3.8

2.ProfilewithtoefilletinconformancewithFigure3.9

3.Concaveprofile,aswelded,conformancewithFigure3.10withdisktestper2.36.6.6

（1）

4.ConcavesmoothprofileconformancewithFigure3.10fullygroundper2.36.6.6

（2）

ThedesignershalldesignatewhenLevelIistoapply;

intheabsenceofsuchdesignation,andforapplicationswherefatigueisnotaconsideration,LevelIIshallbetheminimumacceptablestandard.AWSD1.1Section2.36.6.7

ItisthereforeimportanttonotethatevenintheabsenceofDesignerdesignation,theWeldingInspectorshouldensuretheweldprofilescomplywiththeTable2.7requirementsLevelIIasaminimum.

TherequiredConcavesmoothprofilesasshowninFigure3.10are

Oneshouldnotethefollowingclause

Itisimportanttonotethattheweldprofilesfor2.36.6.6

（2）shallbesmoothandfullyground.

FollowingistheAWSD1.1sectionC2NonMandatoryCommentaryonFatigueBehaviorImprovementbyweldprofiling.（C2.36.6.6FigureC2.20）

Thefiguregivesdescribe2typesofweldprofilegrindingrequirementsnamely;

1.Concaveprofile,aswelded,conformancewithFigure3.10withdisktestper2.36.6.6

（1）

2.ConcavesmoothprofileconformancewithFigure3.10fullygroundper2.36.6.6

（2）

TheAWSD1.1sectionC2.36.6.6,NonMandatoryCommentaryonFatigueBehaviorImprovementbyweldprofilingwasproposedtoensuremoreeffectiveinmaintainingClassX1fatigueperformanceoverawiderangeofthicknesses.Howeverthecommentaryalsorecognizesitshortfall,sayingthatevenbygrindingwiththepermissiblenotchdepthfurtherreducedto0.01in.（0.25mm）;

ifitmerelyflatteningthetopsoftheindividualweldpasses,whileleavingsharpcanyonsinbetween,doeslittletoimprovethefatigueperformance,eventhoughitwouldmeettheletterofthedisktest.

Atighterrequirementwassuggested.ItwassuggestedbytheC2.36.6.6commentarythatitmaybemoreeffectivetogrindtheentireweldprofilesmoothforbothfatiguecategoryIandII.

（WholeoftherelevantsectionofcommentarywasattachedforfurtherreadingAppendixII）.

2.2NDE

Forconformancewiththecodesrequirements,thecodescallforthedetectionofsurfacebreakingandnearsurfacebreakingsignificantdiscontinuities.AWSandAPIcodesbothcallforMPIdetectionofsurfacediscontinuities.Asthegrindingdirection