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| {{#Wiki_filter:Revision1JN4'~'-'0'8012FINALREPORTONSPOT-WELDEDSTRUTSFORSUSQUEHANNASTEAMELECTRICSTATIONUNITS1AND2Preparedby:Checkedby:Approvedby:BECHTELPOWERCORPORATIONSanFrancisco,CaliforniaSeptember29,1978December29,197U(Revision1)(P23-9)o80102$ | | {{#Wiki_filter:Revision1JN4'~'-'0'8012FINALREPORTONSPOT-WELDED STRUTSFORSUSQUEHANNA STEAMELECTRICSTATIONUNITS1AND2Preparedby:Checkedby:Approvedby:BECHTELPOWERCORPORATION SanFrancisco, California September 29,1978December29,197U(Revision 1)(P23-9)o80102$ |
| 0le' Revision1~JN4>"-">OJSG'32TABLEOFCONTENTSSectionTitle~Pae1.02.0PurposeSpot-weldedStruts3~0Background4'DeficiencyanditsSafetyImplications5'ImmediateAction6.0TestProgram7'TechnicalEvaluationofDeficiency8.0CorrectiveAction109.0RepairMethods10'Conclusion14ATTACHMENTS(P23-9)TestReportby'PittsburghTestingLaboratory'estResultsSpecifications*TheAttachmentswerepreviouslytransmittedviaPLA-295datedOctober9,1978andarenotforwardedwiththisreport. | | 0le' Revision1~JN4>"-">OJSG'32TABLEOFCONTENTSSectionTitle~Pae1.02.0PurposeSpot-welded Struts3~0Background 4'Deficiency anditsSafetyImplications 5'Immediate Action6.0TestProgram7'Technical Evaluation ofDeficiency |
| Revision11'PURPOSEThepurposeofthisreportistoprovidefinaldataand.informationasrequiredby10CFR50.55(e)(3)subsequenttothenotificationofareportabledeficiency.Thesubjectdeficiencyisassociatedwithspot/resistanceweldinginstrutmaterial.2.0SPOT-WELDEDSTRUTS2.1StrutsBasicstrutsectionsarelightgage(thicknessvaryingfrom0.105to0.109inch)channelsmanufacturedbycoldformingmildsteelstrip.Thesechannelsec-Vtionsareconnectedtoeachotherinvariousconfigura-tionssuchasback-to-back,back-to-side,orside-to-sidebyusingaweldingprocesscommerciallyknownasspot-weldingorresistancewelding.Thechannelsectionsandbuilt-upsectionsusedonSusquehannaprojectareeithermill-galvanizedorhot-dipgalvanizedafterspot-weldingandaresuppliedbyUnistrutCorporation,Wayne,Michigan;PowerStrut,DivisionofVanHuffelTubeCorporation,Warren,Ohio;andB-LineSystemsIncorporated,Highland,Illinois.Thesewereprocuredasstandardoff-the-shelf,itemswithnoformalQualityAssurance.VariousconfigurationsusedonSusquehannaaregiveninFigureI.Strutmembersareusedinfieldfabricatedsupportsforelectricalraceways,HVACductsandinstrumentation
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| >e4r-'69BQj2..lines.Thegoverningdocumentsaredrawing8856-E-53forelectricalraceways,Specification8856-M-323-CforHVACductsandDrawing8856-JG-16forinstrumenta-tion.Thesupportsaredesignedinaccordancewith'Specifi-cationfortheDesignofCold-formedSteelStructuralMembers'1968Edition),publishedbyAmericanIronandSteelInstitute.Thespot/resistanceweldingprocessconsistsofpassinghighcurrentthroughthethicknessesofadjoiningplatesresultinginmetal-to-metalfusion.Thequalityofaspotweldisdependentonmanyvariablessuchaspres-sureontheelectrodetips,finishofthematerial,presenceofimpuritiesonthematerial,build-upofzincandothercontaminentsontheweldingelectrodes,contactbetweenjoiningsurfaces,voltageandamperage.Therefore,unlesstheseparametersarecloselymoni-toredandcontrolled,theresultmaybeinadequatefusion.3.0BACKGROUNDSincetheuseofstrutmaterialbeganontheSusquehannaPro-ject,therewerethreeisolatedinstanceswhentheadjoiningFchannelsseparatedduringhandlingorassembling.Thesememberlengthswererejected.(P23-9) evision1.)(z-r=.E8612However,inrecentmonthstherehavebeensignificantin-stancesonothernuclearprojectswhereinadequatefusionwasobservedattheweld.spots.Asaresultofth's',onMarch25and26,1978,BechtelfieldengineeringpersonnelperformedaninspectiononUnistrutmemberP-1004A,Power-strutmemberPS-3022andB-LinememberB22-X.ThetestedmemberswerepartofinstalledelectricalracewayandHVACductsupports..Themethodofinspectionconsistedof'sounding'hememberswithaballpeenhammertodetectseparatedspotweldsandverificationoftheseparationbyinsertionofacardbetweenthemembersatthespotwelds.Theinspectionindicatedahighincidenceofspot-weldswithinadequateornofusion.Therefore,ProjectQualityAssurance(QA)issuedManagementCorrectiveActionReport(MCAR)1-23onMarch28,1978.4.0DEFICIENCYANDITSSAFETYIMPLICATIONSBasedupontheresul'tsoftheinspectionasdescribedinSection3.0,itwasdeterminedthat:a.Thedeficiencyisrelatedtospot-weldingtechniqueand/orprocedure.b.Thequalityofthespot-weldingisindeterminate,withoutfurtherinvestigation.Variouscombinationsandconfigurationsofchannelstrutshavebeenusedinthesupportsystems.Individualmembers(P23-9) vision10.8012havebeendesignedascompositesectionsforwhichthecon-nection(spot-weldingusedinthisinstance)betweenadjoin-ingchannelsisreliedupontocarrythepostulatedloadswithinestablisheddesignmargins.Thus,inadequatefusionatthespot-weldingmayresultininadequatestrength,andmayadverselyaffectthesafeoperationoftheplantunderdesignloadingconditions.5.0IMMEDIATEACTIONA'Hold'asimposedonfurtherinstallationofmemberP-1004Aoritsequivalentunlessthememberwasstitch-weldedtodevelopequivalentdesignstrengthofthespot-welding.6.0TESTPROGRAM6.1General.Althoughitwasdeterminedthatadeficiencyexistedinsomespot-weldedmembers,theextentofthede-ficiencywasunknown.Sothefirststepwastoes-tablishthescopeoftheproblem.Sincethereisnopracticalnondestructivemethodforexaminingthesound-Inessofspotweldsintheerectedmaterial,itwasde-cidedtoinitiateadestructivetestprogram.6.2BasisofTestProramTheunderlyingapproachisdescribedbelow.(P23-9)
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| Resion1Jw4'r-''I,:-"Q.Q'lRa.Obtainrepresentativesamples,selectedatrandom,fromthe'nstalledandstockmaterialforallshapesandmanufacturers.b.Performdestructivesheartestonthesamplestoobtainfailureloads.c.Analyzethetestresultsstatisticallyforeachshapeandmanufacturertocomputecorrespondingexpectedstrengthperspot-weldatacertainconfidencelevel.6.3~samlesSampleswereobtainedbyBechtelfieldengineeringpersonnelandsenttoarecognizedtestinglaboratory.Samplesweretypically6"longcontainingtwospot-welds.Forthestockmaterial,twosampleswereobtainedfromeach20'-0"lengthandonlyonesamplefromanygiveninstalledmemberselectedatrandom.Forthcinstalledmaterial,generallyonesamplewasobtainedforevery100feetoftheinstalledquantity.6.4~TestisTestingwasdonebyPittsburghTestingLaboratory(PTL)inPittsburgh,Pennsylvania.TestmethodandproceduresarefullydescribedinPTL'sreport.(SeeAttachmentA).(P,23-9)
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| Revision16.5StatisticalAnalsis>e4-isgasp:g.pBaseduponthetestresults,histogramswereplottedforeachshapeandmanufacturer.Meanandstandarddeviationwerecomputedforeachcase.Thetestresultsgenerallyfollowthenormaldistribution.Theexpectedfailureloadperspotweldwasdeterminedbyusingthemeanofthefailureloadbaseduponthetestresultsandsubtractingoneandahalftimesthestandarddeviation.Thisapproachprovidesmorethan90%confidencelevelfortheexpectedfailureload.Baseduponabovecriteria,theexpectedfailureloadswerecomputedandaregiveninTableI.7.0TECHNICALEVALUATIONOFDEFICIENCY7.1GeneralThetechnicalevaluationinthissectionislimitedtoallstrutmembersinstalledand/oratthejobsitewhicharenotfabricated.7.2DesinCriteriaandTheoreticalConsiderationsAISIspecificationspecifiesallowableshearstrengthperspot-weldtobeequalto1.65kipswithafactorofsafetyof2.5for0.109inchthickness.Thisal-lowableshearisbasedupon"RecommendedPractices(923-9)
| | ==8.0 Corrective== |
| Revision1Jgg-(cg,gg.Q'j'fforResistanceWelding,"AWSC1.1,byAmericanWeldingSociety.Basedonthiscriteria,thefailureloadforaspotshouldbeover4,000pounds.However,inlightoftheproblemassociatedwithspot-welding,itisnecessarytoassessbasesofcoderequirementsandevaluatestructuraladequacyoftheinstalledmaterialwithoutcompromisingthebasicdesignphilosophy.Theconnectionprovidedbyspotweldsbetweenadjoin-ingchannelsectionsisreliedupontomaintaintheintegrityofthebuilt-upsections.Thecalculatedshearinaspotweldinamemberdependsuponmanyvariablessuchasloading,sectionalproperties,endconditionsandifthememberisusedasabeam,brace,columnortie.Theallowableshearof1.65kips/spotspecifiedbythecodeistheupperlimitfordesigningpurpose.However,fromtheevaluationpointofview,itismorerealistictoconsideractualmaximumdesignshearcal-culatedindividuallyasrequiredforeachshape.Sec-ondly,forthestrutmaterial(Fy=33k.s.i.)theallowablebendingstress(Fg)percodeis20k.s.i.for0.105inchthickness.Therefore,thefactorofsafetyforthebendingstressisconsideredtobe1.65whileforthespot-welds,itis2.5,whichisratherhigh.Reasonforthiscouldbeattributedtomanyvariable,w7(P23-9)
| | Action109.0RepairMethods10'Conclusion 14ATTACHMENTS (P23-9)TestReportby'Pittsburgh TestingLaboratory'est ResultsSpecifications |
| Revision1Ju4ra098012affectingtheweldstrength.Forthematerialinques-tiononSusquehanna,anextensivetestprogramhasbeencarriedoutandexpectedfailureloadsforeachshapearewelldefined.Therefore,itisreasonabletoas-sumethatafactorofsafetyof2.0forspot-welds,whichisstillhigherthanthefactoryofsafetyforbendingofthestrutmaterialwouldstillbeadequateandconsistentwiththebasicdesignphilosophy.73Thedesignofframingmembersinthesupportsystemisbaseduponallowableshearof1650lbs.perspotweld.Therefore,tomaintainaminimumsafetyfactorequalto2.0,theexpectedfailureloadmustbe3300lbs.orgreater.7.3.1Thestrutsectionswiththeexpectedfailureloadequaltoorgreaterthan3300lbs/spotweld,areconsideredtobestructurallyadequate.7.3.2However,fortheothersections,furtherevaluationisnecessary.Designloadsonthesupportsystemsaregovernedbymanyconsiderationssuchastypeofsupport,structure,elevation,etc.Forindividualmem-bersinasupport,designshearforcesaddition-allydependuponifthemembersareloadedflex-urallyoraxially.Etisnotedthatforflexuralmembers,shearforcesaregenerallyhigh.
| | *TheAttachments werepreviously transmitted viaPLA-295datedOctober9,1978andarenotforwarded withthisreport. |
| Revision1JhNg<cg>GOjpFortheearlierinvestigation,a5'-0"longmember'sup-portinguniformlydistributedloadwasconsideredtobearepresentativecaseforvariousloadingconditions,andmembershapes,andcomparisonwasmadebetweencom-puteddesignshearsandexpectedfailureloads.However,inthefinalanalysis,actualdesignshearswerecomputedinindividualmembersforallsupport~typesinvariousbuildingsandatdifferenteleva-tions.Theseshearvaluesvaryconsiderably;therefore,theexistingmembers,whichmaybeadequateatacertainlocation,mayneedstrengtheningelsewheredependingontheaforementionedvariables.'nanycase,afac-torofsafetyof2.0hasbeenmaintained.7.4~SummarBaseduponafactorofsafety,of2.0,allshapesaregroupedinthreecategories.CateorIUnistrut:P-5501,P-1001C,P-3301,P-1001AP-1001C3Powerstrut:PS-151,PS-202Theseshapesarestructurallyadequateandneednorepair.
| | Revision11'PURPOSEThepurposeofthisreportistoprovidefinaldataand.information asrequiredby10CFR50.55(e)(3) subsequent tothenotification ofareportable deficiency. |
| CateorIIUnistrut:P-1001,P-5001Powerstrut:PS-201,PS-101,PS-204PS-3080B-Line:.B-12AThesesectionsareconsidereddeficientatcertainlocationsandneedtoberepairedasrequired.CateorIIIUnistrut:P-1004APowerstrut:PS-3022B-LineB-22X,B-11AAllmembersofaboveshapesaretoberepaired/strengthenedtoprovideshearconnectioncapacityequaltotwicethedesignstrengthrequired.8.0CORRECTIVEACTION8.1GeneralCorrectiveactionsaregroupedinseveralcategories.Eachcategoryandcorrespondingactionisdescribedbelow.8.2InstalledandStockMaterial8.2.1PowerstrutPS-3022,IUnistrutP-1004AB-LineB-22X.BasedupontheinspectionbyBechtelfieldengineeringpersonnel,allmaterialofthis-10-(P23-9) evisionlconfigurationwasdeemedtobedeficient,andwillbecompletelyrepairedwithouttakinganycreditfortheexistingspotwelds.8.2.2B-LineB-11A.Installedandstockquantityforthisshapewassmall;therefore,.nosampleswereobtained.Intheabsenceofanytestdataontheexistingspotwelds,thissectionwillberepairedtodeveloprequireddesigncapacitytomeetthedesigncriteria.8.2.3Powerstrut:PS-151,PS-202Unistrut:P-5501,P1001G,P-3301,P-1001A,IP-1001C3BaseduponthetechnicalevaluationinSection7.0,existingspot-weldingisadequateandwillperformsatisfactorilyunderdesignloads.Therefore,nofurtheractionisdeemedneces-sary.8.2.4Powerstrut;PS-201,PS-101,PS-204,PS-3080Unistrut:P-1001,P-5001IB-Line:B12A-11-(P23-1/1)
| | Thesubjectdeficiency isassociated withspot/resistance weldinginstrutmaterial. |
| | 2.0SPOT-WELDED STRUTS2.1StrutsBasicstrutsectionsarelightgage(thickness varyingfrom0.105to0.109inch)channelsmanufactured bycoldformingmildsteelstrip.Thesechannelsec-Vtionsareconnected toeachotherinvariousconfigura-tionssuchasback-to-back, back-to-side, orside-to-side byusingaweldingprocesscommercially knownasspot-weldingorresistance welding.Thechannelsectionsandbuilt-upsectionsusedonSusquehanna projectareeithermill-galvanized orhot-dipgalvanized afterspot-welding andaresuppliedbyUnistrutCorporation, Wayne,Michigan; PowerStrut,DivisionofVanHuffelTubeCorporation, Warren,Ohio;andB-LineSystemsIncorporated, |
| | : Highland, Illinois. |
| | Thesewereprocuredasstandardoff-the-shelf, itemswithnoformalQualityAssurance. |
| | Variousconfigurations usedonSusquehanna aregiveninFigureI.Strutmembersareusedinfieldfabricated supportsforelectrical |
| | : raceways, HVACductsandinstrumentation |
| | >e4r-'69BQj2.. |
| | lines.Thegoverning documents aredrawing8856-E-53 forelectrical |
| | : raceways, Specification 8856-M-323-C forHVACductsandDrawing8856-JG-16 forinstrumenta-tion.Thesupportsaredesignedinaccordance with'Specifi-cationfortheDesignofCold-formed SteelStructural Members'1968 Edition), |
| | published byAmericanIronandSteelInstitute. |
| | Thespot/resistance weldingprocessconsistsofpassinghighcurrentthroughthethicknesses ofadjoining platesresulting inmetal-to-metal fusion.Thequalityofaspotweldisdependent onmanyvariables suchaspres-sureontheelectrode tips,finishofthematerial, presenceofimpurities onthematerial, build-upofzincandothercontaminents ontheweldingelectrodes, contactbetweenjoiningsurfaces, voltageandamperage. |
| | Therefore, unlesstheseparameters arecloselymoni-toredandcontrolled, theresultmaybeinadequate fusion.3.0BACKGROUND SincetheuseofstrutmaterialbeganontheSusquehanna Pro-ject,therewerethreeisolatedinstances whentheadjoining Fchannelsseparated duringhandlingorassembling. |
| | Thesememberlengthswererejected. |
| | (P23-9) evision1.)(z-r=.E8612However,inrecentmonthstherehavebeensignificant in-stancesonothernuclearprojectswhereinadequate fusionwasobservedattheweld.spots.Asaresultofth's',onMarch25and26,1978,Bechtelfieldengineering personnel performed aninspection onUnistrutmemberP-1004A,Power-strutmemberPS-3022andB-LinememberB22-X.Thetestedmemberswerepartofinstalled electrical racewayandHVACductsupports. |
| | .Themethodofinspection consisted of'sounding'he memberswithaballpeenhammertodetectseparated spotweldsandverification oftheseparation byinsertion ofacardbetweenthemembersatthespotwelds.Theinspection indicated ahighincidence ofspot-welds withinadequate ornofusion.Therefore, ProjectQualityAssurance (QA)issuedManagement Corrective ActionReport(MCAR)1-23onMarch28,1978.4.0DEFICIENCY ANDITSSAFETYIMPLICATIONS Basedupontheresul'tsoftheinspection asdescribed inSection3.0,itwasdetermined that:a.Thedeficiency isrelatedtospot-welding technique and/orprocedure. |
| | b.Thequalityofthespot-welding isindeterminate, withoutfurtherinvestigation. |
| | Variouscombinations andconfigurations ofchannelstrutshavebeenusedinthesupportsystems.Individual members(P23-9) vision10.8012havebeendesignedascomposite sectionsforwhichthecon-nection(spot-welding usedinthisinstance) betweenadjoin-ingchannelsisreliedupontocarrythepostulated loadswithinestablished designmargins.Thus,inadequate fusionatthespot-welding mayresultininadequate |
| | : strength, andmayadversely affectthesafeoperation oftheplantunderdesignloadingconditions. |
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| Revision1igu7.0912Thesemembersdonotmeetthedesigncriteria,therefore,adetailedre-analysisandredesignhasbeenperformedtocomputerequiredadditionalstrengthanddesigndrawingshavebeenpreparedtoshowthenecessaryrepairdetails.There-quiredrepairwillbeperformedontheinstalledandstockmaterial.Oncompletionoftherepair,thestrutmaterialwillsatisfythedesigncri-teria.8.3StrutMaterialtobeReceivedintheFutureUntilnow,thestrutmaterialwasprocuredasastan-dard'offtheshelf'tem.However,inlightoftheproblemexperiencedwiththespot-welding,anewspeci-.fication8856-C-92(seeAttachmentC)wasdevelopedforprocurementof,allspot-weldedstrutsinthefuture.TheresultsofthetestingbyPTLpositivelyindicatethatthespot-weldsonaplainmaterialhavemuchhigherstrengththanspot-weldsonmill-galvanizedmaterial.Therefore,thespecificationstipulatesthatstrutmaterialtobecoatedafterspotwelding.Inadditiontothis,toprovideareasonableassuranceofattainingthedesignstrength,thesupplierisre-quiredtointroduceadestructivetestingprogramontheproductionsamplesandnomaterialwillbeshippedtoSusquehannajobsiteunlessitmeetstheacceptance.criteria.Thisactionshouldpreventtherecurrenceofthisprobleminthefuture.(P23-1/2) | | ==5.0 IMMEDIATE== |
| Revision19.0REPAIRMETHODSN''4'Kid+Q3,+r,'.1GeneralConstructionhasbeenprovidedtheoptiontoselectanyoneofthefollowingmethodsonacase-by-casebasis.9.ThismethodistoreplacethedeficientmaterialwithnewmaterialtobeprocuredperSpecification8856-C-92(seeAttachmentC).9.3MechanicalFastenersSecondmethodistoprovide1/4"dia.self-drillingandself-tappingmetalscrewstoobtainrequiredshearstrength.These,screwswillbeprocuredperSpecification8856-C-91(seeAttachmentC).Inordertoassurestrengthrequirementsforthescrews,itisrequiredtoperformadestructivesheartestonsamplesandeachlotmustmeettheacceptancecriteria.Inadditiontoself-drillingandself-tappingscrews,othermechanicalfastenersarebeingconsideredsuchaspop-rivetsorclamps.Ifthesearedeterminedtobetechnicallyacceptable,theywillbeusedasalternatetothescrews.-13-(P23-1/3)' | | ACTIONA'Hold'asimposedonfurtherinstallation ofmemberP-1004Aoritsequivalent unlessthememberwasstitch-weldedtodevelopequivalent designstrengthofthespot-welding.6.0TESTPROGRAM6.1General.Althoughitwasdetermined thatadeficiency existedinsomespot-welded members,theextentofthede-ficiencywasunknown.Sothefirststepwastoes-tablishthescopeoftheproblem.Sincethereisnopractical nondestructive methodforexamining thesound-Inessofspotweldsintheerectedmaterial, itwasde-cidedtoinitiateadestructive testprogram.6.2BasisofTestProramTheunderlying approachisdescribed below.(P23-9) |
| ision19.II~VeldknThirdapproachistoprovideintermittent.stitchweldingatthejointbetweenchannelsand/orchan-nelandsideplate. | | Resion1Jw4'r-''I,:-"Q.Q'lR a.Obtainrepresentative samples,selectedatrandom,fromthe'nstalled andstockmaterialforallshapesandmanufacturers. |
| | b.Performdestructive sheartestonthesamplestoobtainfailureloads.c.Analyzethetestresultsstatistically foreachshapeandmanufacturer tocomputecorresponding expectedstrengthperspot-weld atacertainconfidence level.6.3~samlesSampleswereobtainedbyBechtelfieldengineering personnel andsenttoarecognized testinglaboratory. |
| | Samplesweretypically 6"longcontaining twospot-welds. |
| | Forthestockmaterial, twosampleswereobtainedfromeach20'-0"lengthandonlyonesamplefromanygiveninstalled memberselectedatrandom.Forthcinstalled |
| | : material, generally onesamplewasobtainedforevery100feetoftheinstalled quantity. |
| | 6.4~TestisTestingwasdonebyPittsburgh TestingLaboratory (PTL)inPittsburgh, Pennsylvania. |
| | Testmethodandprocedures arefullydescribed inPTL'sreport.(SeeAttachment A).(P,23-9) |
| | |
| | Revision16.5Statistical Analsis>e4-isgasp:g.pBaseduponthetestresults,histograms wereplottedforeachshapeandmanufacturer. |
| | Meanandstandarddeviation werecomputedforeachcase.Thetestresultsgenerally followthenormaldistribution. |
| | Theexpectedfailureloadperspotweldwasdetermined byusingthemeanofthefailureloadbaseduponthetestresultsandsubtracting oneandahalftimesthestandarddeviation. |
| | Thisapproachprovidesmorethan90%confidence levelfortheexpectedfailureload.Baseduponabovecriteria, theexpectedfailureloadswerecomputedandaregiveninTableI.7.0TECHNICAL EVALUATION OFDEFICIENCY 7.1GeneralThetechnical evaluation inthissectionislimitedtoallstrutmembersinstalled and/oratthejobsitewhicharenotfabricated. |
| | 7.2DesinCriteriaandTheoretical Considerations AISIspecification specifies allowable shearstrengthperspot-weld tobeequalto1.65kipswithafactorofsafetyof2.5for0.109inchthickness. |
| | Thisal-lowableshearisbasedupon"Recommended Practices (923-9) |
| | Revision1Jgg-(cg,gg.Q'j'f forResistance Welding," |
| | AWSC1.1,byAmericanWeldingSociety.Basedonthiscriteria, thefailureloadforaspotshouldbeover4,000pounds.However,inlightoftheproblemassociated withspot-welding, itisnecessary toassessbasesofcoderequirements andevaluatestructuraladequacyoftheinstalled materialwithoutcompromising thebasicdesignphilosophy. |
| | Theconnection providedbyspotweldsbetweenadjoin-ingchannelsectionsisreliedupontomaintaintheintegrity ofthebuilt-upsections. |
| | Thecalculated shearinaspotweldinamemberdependsuponmanyvariables suchasloading,sectional properties, endconditions andifthememberisusedasabeam,brace,columnortie.Theallowable shearof1.65kips/spot specified bythecodeistheupperlimitfordesigning purpose.However,fromtheevaluation pointofview,itismorerealistic toconsideractualmaximumdesignshearcal-culatedindividually asrequiredforeachshape.Sec-ondly,forthestrutmaterial(Fy=33k.s.i.)theallowable bendingstress(Fg)percodeis20k.s.i.for0.105inchthickness. |
| | Therefore, thefactorofsafetyforthebendingstressisconsidered tobe1.65whileforthespot-welds, itis2.5,whichisratherhigh.Reasonforthiscouldbeattributed tomanyvariable, w7(P23-9) |
| | Revision1Ju4ra098012affecting theweldstrength. |
| | Forthematerialinques-tiononSusquehanna, anextensive testprogramhasbeencarriedoutandexpectedfailureloadsforeachshapearewelldefined.Therefore, itisreasonable toas-sumethatafactorofsafetyof2.0forspot-welds, whichisstillhigherthanthefactoryofsafetyforbendingofthestrutmaterialwouldstillbeadequateandconsistent withthebasicdesignphilosophy. |
| | 73Thedesignofframingmembersinthesupportsystemisbaseduponallowable shearof1650lbs.perspotweld.Therefore, tomaintainaminimumsafetyfactorequalto2.0,theexpectedfailureloadmustbe3300lbs.orgreater.7.3.1Thestrutsectionswiththeexpectedfailureloadequaltoorgreaterthan3300lbs/spotweld,areconsidered tobestructurally adequate. |
| | 7.3.2However,fortheothersections, furtherevaluation isnecessary. |
| | Designloadsonthesupportsystemsaregovernedbymanyconsiderations suchastypeofsupport,structure, elevation, etc.Forindividual mem-bersinasupport,designshearforcesaddition-allydependuponifthemembersareloadedflex-urallyoraxially.Etisnotedthatforflexuralmembers,shearforcesaregenerally high. |
| | Revision1JhNg<cg>GOjpFortheearlierinvestigation, a5'-0"longmember'sup-portinguniformly distributed loadwasconsidered tobearepresentative caseforvariousloadingconditions, andmembershapes,andcomparison wasmadebetweencom-puteddesignshearsandexpectedfailureloads.However,inthefinalanalysis, actualdesignshearswerecomputedinindividual membersforallsupport~typesinvariousbuildings andatdifferent eleva-tions.Theseshearvaluesvaryconsiderably; therefore, theexistingmembers,whichmaybeadequateatacertainlocation, mayneedstrengthening elsewhere depending ontheaforementioned variables.'n anycase,afac-torofsafetyof2.0hasbeenmaintained. |
| | 7.4~SummarBaseduponafactorofsafety,of2.0,allshapesaregroupedinthreecategories. |
| | CateorIUnistrut: |
| | P-5501,P-1001C,P-3301,P-1001AP-1001C3Powerstrut: |
| | PS-151,PS-202Theseshapesarestructurally adequateandneednorepair. |
| | CateorIIUnistrut:P-1001,P-5001Powerstrut: |
| | PS-201,PS-101,PS-204PS-3080B-Line:.B-12AThesesectionsareconsidered deficient atcertainlocations andneedtoberepairedasrequired. |
| | CateorIIIUnistrut:P-1004APowerstrut: |
| | PS-3022B-LineB-22X,B-11AAllmembersofaboveshapesaretoberepaired/ |
| | strengthened toprovideshearconnection capacityequaltotwicethedesignstrengthrequired. |
| | |
| | ==8.0 CORRECTIVE== |
| | ACTION8.1GeneralCorrective actionsaregroupedinseveralcategories. |
| | Eachcategoryandcorresponding actionisdescribed below.8.2Installed andStockMaterial8.2.1Powerstrut PS-3022,IUnistrutP-1004AB-LineB-22X.Basedupontheinspection byBechtelfieldengineering personnel, allmaterialofthis-10-(P23-9) evisionlconfiguration wasdeemedtobedeficient, andwillbecompletely repairedwithouttakinganycreditfortheexistingspotwelds.8.2.2B-LineB-11A.Installed andstockquantityforthisshapewassmall;therefore,. |
| | nosampleswereobtained. |
| | Intheabsenceofanytestdataontheexistingspotwelds,thissectionwillberepairedtodeveloprequireddesigncapacitytomeetthedesigncriteria. |
| | 8.2.3Powerstrut: |
| | PS-151,PS-202Unistrut: |
| | P-5501,P1001G,P-3301,P-1001A,IP-1001C3Baseduponthetechnical evaluation inSection7.0,existingspot-welding isadequateandwillperformsatisfactorily underdesignloads.Therefore,nofurtheractionisdeemedneces-sary.8.2.4Powerstrut; PS-201,PS-101,PS-204,PS-3080Unistrut: |
| | P-1001,P-5001IB-Line:B12A-11-(P23-1/1) |
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| | Revision1igu7.0912Thesemembersdonotmeetthedesigncriteria, therefore,adetailedre-analysis andredesignhasbeenperformed tocomputerequiredadditional strengthanddesigndrawingshavebeenpreparedtoshowthenecessary repairdetails.There-quiredrepairwillbeperformed ontheinstalled andstockmaterial. |
| | Oncompletion oftherepair,thestrutmaterialwillsatisfythedesigncri-teria.8.3StrutMaterialtobeReceivedintheFutureUntilnow,thestrutmaterialwasprocuredasastan-dard'offtheshelf'tem. |
| | However,inlightoftheproblemexperienced withthespot-welding, anewspeci-.fication8856-C-92 (seeAttachment C)wasdeveloped forprocurement of,allspot-welded strutsinthefuture.TheresultsofthetestingbyPTLpositively indicatethatthespot-welds onaplainmaterialhavemuchhigherstrengththanspot-welds onmill-galvanized material. |
| | Therefore, thespecification stipulates thatstrutmaterialtobecoatedafterspotwelding. |
| | Inadditiontothis,toprovideareasonable assuranceofattaining thedesignstrength, thesupplierisre-quiredtointroduce adestructive testingprogramontheproductionsamplesandnomaterialwillbeshippedtoSusquehanna jobsiteunlessitmeetstheacceptance |
| | .criteria. |
| | Thisactionshouldpreventtherecurrenceofthisprobleminthefuture.(P23-1/2) |
| | Revision19.0REPAIRMETHODSN''4'Kid+Q3,+r,'. |
| | 1GeneralConstruction hasbeenprovidedtheoptiontoselectanyoneofthefollowing methodsonacase-by-case basis.9.Thismethodistoreplacethedeficient materialwithnewmaterialtobeprocuredperSpecification 8856-C-92 (seeAttachment C).9.3Mechanical Fasteners Secondmethodistoprovide1/4"dia.self-drilling andself-tapping metalscrewstoobtainrequiredshearstrength. |
| | These,screwswillbeprocuredperSpecification 8856-C-91 (seeAttachment C).Inordertoassurestrengthrequirements forthescrews,itisrequiredtoperformadestructive sheartestonsamplesandeachlotmustmeettheacceptance criteria.Inadditiontoself-drilling andself-tapping screws,othermechanical fasteners arebeingconsidered suchaspop-rivets orclamps.Ifthesearedetermined tobetechnically acceptable, theywillbeusedasalternate tothescrews.-13-(P23-1/3) |
| | ' |
| | ision19.II~VeldknThirdapproachistoprovideintermittent |
| | .stitchweldingatthejointbetweenchannelsand/orchan-nelandsideplate. |
|
| |
|
| ==10.0CONCLUSION== | | ==10.0CONCLUSION== |
| Oncompletionoftherequiredrepair/replacementoftheexistingspot-weldedstrutsdeterminedtobedeficient,theexistingsupportsystemswillbestructurallyade-quatetosatisfythedesignrequirements.Secondly,pro-curementofnewspot-weldedstrutmaterialpernewspec-ification(seeAttachmentC),willprovideadequateas-suranceofpreventingtherecurrenceofthisprobleminthefuture..-14-(F23-1/4)
| |
| Hevislon1TABLE1EXPECTEDFAILURELOADS~FE82'80C99480StandardExpectedFailureLoadMeanDeviation=A-1.5BMeuufacturerMember(1bs)(1bs)(lbs)RemarksUnistrut(A)(B)P-10014140-1213P-550154991229P-50014357-,1072P-1001C53861033P-3301'4651025P-1001A4192554P-1001C3,5186629232136563837392833614243Cat.IICat.ICat.IICat.ICat.ICat.ICat.I(Backtoback)P-1001C351264584439Cat.IPowerstrut(Backtoside)PS-2014418,1194PS-1515533892PS-1013855782PS-20441502233PS-308041261252262741952682801Cat.IICat.ICat.IICat.IIICat.II(Backtoback).PS-30804666(Backtoside)PS-2025783B12A356515111317240039501590Cat.IICat,ICateIINote'.1.Abovenumbersinthetablearebasedupononespotveld.2.ForexplanationofRemarks"column,refertosection7.4.3.ForshapesinFigure1andnotintableabove(i.e.thoseinCategoryIII),refertosection7.4.(P23-10)
| |
|
| |
|
| FIGURE1STRUTSHAPESANDIDENTIFICATIONRevision1~Shae0UnistrutP-5001PowerstrutPS-101B-LineB-11A~ShaeRUnistrutP-5501PowerstrutPS-151B-LineB-12A~ShaeKUnistrutP-1001PowerstrutPS-201.~ShaeNUnistrutP-1004APowerstrutPS-3022B-Line,B-22X3~haeNUnistrutP-1001C3PowerstrutPS-3080~ShaeLUnistrutP-1001CPowerstrutPG-204~Shae0UnistrutP-1001APowerstrutPS-202ShauePUuiattutP-3301}}
| | Oncompletion oftherequiredrepair/replacement oftheexistingspot-welded strutsdetermined tobedeficient, theexistingsupportsystemswillbestructurally ade-quatetosatisfythedesignrequirements. |
| | : Secondly, pro-curementofnewspot-welded strutmaterialpernewspec-ification (seeAttachment C),willprovideadequateas-suranceofpreventing therecurrence ofthisprobleminthefuture..-14-(F23-1/4) |
| | Hevislon1TABLE1EXPECTEDFAILURELOADS~FE82'80C99480StandardExpectedFailureLoadMeanDeviation |
| | =A-1.5BMeuufactur erMember(1bs)(1bs)(lbs)RemarksUnistrut(A)(B)P-10014140-1213P-550154991229P-50014357-,1072P-1001C53861033P-3301'4651025P-1001A4192554P-1001C3,5186 629232136563837392833614243Cat.IICat.ICat.IICat.ICat.ICat.ICat.I(Backtoback)P-1001C351264584439Cat.IPowerstrut (Backtoside)PS-2014418,1194PS-1515533892PS-1013855782PS-20441502233PS-308041261252262741952682801Cat.IICat.ICat.IICat.IIICat.II(Backtoback).PS-30804666(Backtoside)PS-2025783B12A356515111317240039501590Cat.IICat,ICateIINote'.1.Abovenumbersinthetablearebasedupononespotveld.2.Forexplanation ofRemarks"column,refertosection7.4.3.ForshapesinFigure1andnotintableabove(i.e.thoseinCategoryIII),refertosection7.4.(P23-10) |
| | |
| | FIGURE1STRUTSHAPESANDIDENTIFICATION Revision1~Shae0UnistrutP-5001Powerstrut PS-101B-LineB-11A~ShaeRUnistrutP-5501Powerstrut PS-151B-LineB-12A~ShaeKUnistrutP-1001Powerstrut PS-201.~ShaeNUnistrutP-1004APowerstrut PS-3022B-Line,B-22X3~haeNUnistrutP-1001C3Powerstrut PS-3080~ShaeLUnistrutP-1001CPowerstrut PG-204~Shae0UnistrutP-1001APowerstrut PS-202ShauePUuiattutP-3301}} |
|
|---|
Category:DEFICIENCY REPORTS (PER 10CFR50.55E & PART 21)
MONTHYEARML20236N6751998-07-0909 July 1998
Part 21 & Deficiency Rept Re Notification of Potential Safety Hazard from Breakage of Cast Iron Suction Heads in Apkd Type Pumps.Caused by Migration of Suction Head Journal Sleeve Along Lower End of Pump Shaft.Will Inspect Pumps
ML20140A9661997-05-29029 May 1997
Part 21 Rept Re Ksv Emergency Diesel Generator Power Piston Failure.Caused by Jacket Water in Combustion Chamber. Recommends That Users Verify That Crown Thickness at Valve Cutout Be 100 Minimum
ML20137G6261997-03-25025 March 1997
Svcs Part 21 Rept Re Emergency Generators Installed at Zion Station Which Developed Significant Drop in Crankcase Lube Oil Level.Caused by Crack in Liner Wall,Allowing Jacket Water to Enter Chamber
ML20117G4641996-05-14014 May 1996
Part 21 Rept Re Cooper Bessemer Reciprocating Products,Div of Cooper Cameron Corp,Issued Ltr to Define Utils/Plants Containing Similar Equipment as Supplied on Cooper Bessemer Ksv & Enterprise Dsr EDGs
ML18017A0421992-12-14014 December 1992
Suppl to 921127 Part 21 Rept Re High Air Concentration in Reactor Bldg Making Area Uninhabitable for Retrieving Air Filters,Per NUREG-0737,Item II.F.1.Util Current Position Re Fuel Pool Cooling Issues Contrary to Reg Guide 1.3
ML18026A2481992-11-27027 November 1992
Part 21 Rept Re Substantial Safety Hazard in Design of Facility for Loss of Normal Spent Fuel Pool Cooling
ML19325C9521989-09-29029 September 1989
Part 21 Rept Re Potential Common Failure of SMB-000 & SMB-00 Cam Type Torque Switches Supplied Prior to 1981 & 1976. Vendor Recommends That Switch W/Fiber Spacer Be Replaced
ML20211P7211987-02-23023 February 1987
Part 21 Rept Re Rockbestos Coaxial Cable Used in Sorrento Electronics Digital & Analog high-range Radiation Monitor. Insulation Resistance at High Temp Not High Enough for Ion Chamber & Associated Electronics to Operate Properly
ML20212E5631986-12-19019 December 1986
Part 21 Rept Re Valve Problem.Houghto 620 Lubricant Attacks & Degrades Aluminum in Valves.Valves Have Been or Being Rebuilt
ML20215G5351986-10-10010 October 1986
Part 21 Rept Re Vendor Tests of air-operated Diaphragm Valves Revealing Natural Frequencies Less than Required Values of 33 Hz.Initially Reported on 841227.No Adverse Effects Noted During Testing
ML20203F6471986-07-23023 July 1986
Part 21 Rept Re Morrison-Knudsen Undersized Welds at Plant. Initially Reported on 860630.Study Concluded That Welds Not Cause for Failure of Plant.Welds Will Be Repaired by Vendor
ML20206S0841986-06-30030 June 1986
Part 21 Rept Re Possible Cut Wires in Wire Harness of Bbc Brown Boveri K600/K800 Circuit Breakers.Initially Reported on 860509.Safety Implications Listed.Gear Guard Designed to Prevent Cut Wires
ML20197H1991986-05-0909 May 1986
Part 21 Rept Re Hilti Fastening Sys Anchor Bolts Failing to Meet Average Ultimate Tensile Loads.Initially Reported on 860509.Design Review & Resolutions of Installed Items Underway
ML20154K3611986-03-0505 March 1986
Part 21 Rept Re Possible Wiring Defect in Fabricated Primer Chamber Assemblies for Standby Liquid Control Valves. Initially Reported on 860214.Listed Corrective Actions Will Be Completed by 860328
ML20140A5281985-12-19019 December 1985
Part 21 Rept Forwarding Ltr Sent to Customers Re Check Valves Missing Lock Welds on Hinge Supports or Hinge Support Capscrews,Per 851121 Request.List of Customers Receiving Ltr Also Encl
ML20138F5631985-12-0505 December 1985
Part 21 Rept Re Failure to Perform Calculations for Two 6-inch Insp Nozzles.Purchaser Notified Not to Place Vessels Into Svc.Design Spec & Rept Will Be Revised to Include Insp Openings
ML20134A9511985-10-0808 October 1985
Part 21 Rept Re Defect in Valve Stems Bearing Heat Number 3876.Entire Stem/Disc Assembly Will Be Replaced Upon Request.Replacement Stem Assembly Will Be Supplied Under Unique Part Number 106626-10
ML20134B0031985-09-26026 September 1985
Part 21 Rept Re Cracked Stem Assembly Detected in 3/4-inch Yarway Welbond Valve at non-nuclear Facility.Investigation Revealed Leakage Caused by Void in Bar Stock.Valves Sold to Nuclear Facilities Contained Stems.Review Continuing
ML20137G1121985-08-22022 August 1985
Part 21 Rept Re Separation of Piston from Connecting Rod on Cooper-Bessemer Reciprocating Div Ksv Engine.Initially Reported on 850304.Engine Returned,Rebuilt & Inspected.No Future Problems Foreseen
ML20108B5611985-03-0404 March 1985
Part 21 Rept Re Defective Engine Used for Driving Standby Power Generator at Facility.Caused by Loosened Attachments Separating Piston from Rod.Engine Will Be Repaired Prior to Installation
PLA-2355, Revised Final Deficiency Rept Re RHR Throttling Valves. Initially Reported on 820316.Reversal of Valve Disks & Valves No Longer Considered Necessary1984-12-10010 December 1984
Revised Final Deficiency Rept Re RHR Throttling Valves. Initially Reported on 820316.Reversal of Valve Disks & Valves No Longer Considered Necessary
PLA-2230, Final Deficiency Rept Re Electrical Separation Inside Multiple Div Junction & Pull Boxes.Initially Reported on 830721.Drawings Revised to Clarify &/Or Define Sparation Requirements for Use W/Junction & Pull Boxes1984-06-28028 June 1984
Final Deficiency Rept Re Electrical Separation Inside Multiple Div Junction & Pull Boxes.Initially Reported on 830721.Drawings Revised to Clarify &/Or Define Sparation Requirements for Use W/Junction & Pull Boxes
PLA-2118, Final Part 21/deficiency Rept Re Clamps on CRD Insert/ Withdrawal Lines.Initially Reported on 831209.Outer Pedestal Modified Due to Lack of Sufficient Axial Restraint Capacity of Inner Pedestal Support1984-06-18018 June 1984
Final Part 21/deficiency Rept Re Clamps on CRD Insert/ Withdrawal Lines.Initially Reported on 831209.Outer Pedestal Modified Due to Lack of Sufficient Axial Restraint Capacity of Inner Pedestal Support
PLA-2215, Final Deficiency Rept Re Base Metal Cracking & Bending of Angle Fittings Mfg by Unistrut,Powerstrut & B-Line Used on Class IE Electrical Raceways & Category 1 HVAC Supports. Initially Reported on 840206.Spec Revised1984-06-0101 June 1984
Final Deficiency Rept Re Base Metal Cracking & Bending of Angle Fittings Mfg by Unistrut,Powerstrut & B-Line Used on Class IE Electrical Raceways & Category 1 HVAC Supports. Initially Reported on 840206.Spec Revised
PLA-2189, Final Part 21 Rept Re GE Reactor Mode Switch.Initially Reported on 830407.Mode Switch Design Modified,Per Franklin Inst Research Lab Recommendations1984-05-21021 May 1984
Final Part 21 Rept Re GE Reactor Mode Switch.Initially Reported on 830407.Mode Switch Design Modified,Per Franklin Inst Research Lab Recommendations
ML20084C2851984-04-19019 April 1984
Final Deficiency Rept Re Waterhammer Loading of Scram Discharge Vol (SDV) Vent & Drain Lines After Opening SDV Vent & Drain Valves on Scram Reset.Initially Reported on 830628.Vent Line Supports Will Be Modified Prior to 841231
PLA-2180, Final Part 21/deficiency Rept Re Improper Relief Valve Settings,Design Pressures & Temps.Initially Reported on 831118.Calculations Performed Assure Lines Adequate for Intended Svc1984-04-19019 April 1984
Final Part 21/deficiency Rept Re Improper Relief Valve Settings,Design Pressures & Temps.Initially Reported on 831118.Calculations Performed Assure Lines Adequate for Intended Svc
PLA-2166, Part 21 Rept Re Failure of Crosby IMF-2 Solenoids Supplied by Ge.Initially Reported on 840403.Licensee & GE Jointly Developed Test Procedures to Bench Test Spares & Solenoids on Both Units.Testing Complete on Unit 11984-04-0909 April 1984
Part 21 Rept Re Failure of Crosby IMF-2 Solenoids Supplied by Ge.Initially Reported on 840403.Licensee & GE Jointly Developed Test Procedures to Bench Test Spares & Solenoids on Both Units.Testing Complete on Unit 1
PLA-2137, Revised Final Deficiency Rept Re Fraying of Hydrogen Recombiner Cables.Initially Reported on 830728.Fraying Caused by Handling Process for Shipment,Installation & Testing.Cables Repaired1984-03-23023 March 1984
Revised Final Deficiency Rept Re Fraying of Hydrogen Recombiner Cables.Initially Reported on 830728.Fraying Caused by Handling Process for Shipment,Installation & Testing.Cables Repaired
PLA-2140, Second Interim Deficiency Rept Re Base Metal Cracking in Angle Fittings.Initially Reported on 840206.Angle Fittings Added to Defective Device List & Conduit Installation Spec Revised.Also Reportable Per 10CFR211984-03-22022 March 1984
Second Interim Deficiency Rept Re Base Metal Cracking in Angle Fittings.Initially Reported on 840206.Angle Fittings Added to Defective Device List & Conduit Installation Spec Revised.Also Reportable Per 10CFR21
PLA-2074, Third Interim Deficiency Rept Re Electrical Separation Inside Multiple Division Junction & Pull Box.Initially Reported on 830721.Design Basis Criteria & Barrier Configuration Established.Also Reported Per Part 211984-03-20020 March 1984
Third Interim Deficiency Rept Re Electrical Separation Inside Multiple Division Junction & Pull Box.Initially Reported on 830721.Design Basis Criteria & Barrier Configuration Established.Also Reported Per Part 21
PLA-2120, Interim Part 21/deficiency Rept Re Base Metal Cracking in Fittings Used on Class IE Electrical Raceways & HVAC Supports.Initially Reported on 840206.Final Rept Expected Prior to Initial Criticality1984-03-0707 March 1984
Interim Part 21/deficiency Rept Re Base Metal Cracking in Fittings Used on Class IE Electrical Raceways & HVAC Supports.Initially Reported on 840206.Final Rept Expected Prior to Initial Criticality
PLA-2103, Final Deficiency Rept Re Cavitation of Jet Pumps Due to Induction Heating Stress Improvement Cooling.Initially Reported on 831206.No Erosion Found.Also Reportable Per Part 21.Item Not Reportable Per 10CFR50.55(e)1984-03-0606 March 1984
Final Deficiency Rept Re Cavitation of Jet Pumps Due to Induction Heating Stress Improvement Cooling.Initially Reported on 831206.No Erosion Found.Also Reportable Per Part 21.Item Not Reportable Per 10CFR50.55(e)
PLA-2075, Second Interim Deficiency Rept Re Improper Relief Valve Setting,Design Pressures & Design Temp within Several Sys. Initially Reported on 831118.Spec M-199 Revised & Code Data Repts Amended.Also Reported Per Part 211984-03-0202 March 1984
Second Interim Deficiency Rept Re Improper Relief Valve Setting,Design Pressures & Design Temp within Several Sys. Initially Reported on 831118.Spec M-199 Revised & Code Data Repts Amended.Also Reported Per Part 21
PLA-2089, Final Deficiency & Part 21 Repts Re Safety Parameter Display Sys Technology Energy Corp Model 156 Isolators.Initially Reported on 840106.Non-IE Power Supply Will Be Provided for Isolator Prior to End of First Refueling1984-02-27027 February 1984
Final Deficiency & Part 21 Repts Re Safety Parameter Display Sys Technology Energy Corp Model 156 Isolators.Initially Reported on 840106.Non-IE Power Supply Will Be Provided for Isolator Prior to End of First Refueling
PLA-2062, Final Deficiency Rept Re Bechtel Failure to Accomplish Design Verification of safety-related Power & Control Cables.Caused by Failure to Complete Required Cable Length Verification.Deficiency Not Reportable Per 10CFR50.55(e)1984-02-13013 February 1984
Final Deficiency Rept Re Bechtel Failure to Accomplish Design Verification of safety-related Power & Control Cables.Caused by Failure to Complete Required Cable Length Verification.Deficiency Not Reportable Per 10CFR50.55(e)
PLA-2073, Final Part 21 Rept Re Hydrogen Catalyst Used in Comsip Custom Line Model K-IV Containment Gas Monitoring Panels. Initially Reported on 840113.Comsip Redesigned Catalyst Will Be Installed1984-02-13013 February 1984
Final Part 21 Rept Re Hydrogen Catalyst Used in Comsip Custom Line Model K-IV Containment Gas Monitoring Panels. Initially Reported on 840113.Comsip Redesigned Catalyst Will Be Installed
PLA-2063, Interim Part 21 Rept Re Safety Parameter Display Sys Model 156 Isolators Mfg by Technology for Energy Corp (Tec). Initially Reported on 840106.All Tec Isolators Reviewed for Corrective Actions1984-02-0606 February 1984
Interim Part 21 Rept Re Safety Parameter Display Sys Model 156 Isolators Mfg by Technology for Energy Corp (Tec). Initially Reported on 840106.All Tec Isolators Reviewed for Corrective Actions
PLA-2045, Followup Deficiency Rept Re Mod of RHR Globe Valves F017A & FO17B to Enable Valves in Shutdown Cooling Mode to Perform W/O Adverse Cavitation & Vibration at Low Flow Rates.Initially Reported on 811112.Valves Replaced1984-01-25025 January 1984
Followup Deficiency Rept Re Mod of RHR Globe Valves F017A & FO17B to Enable Valves in Shutdown Cooling Mode to Perform W/O Adverse Cavitation & Vibration at Low Flow Rates.Initially Reported on 811112.Valves Replaced
PLA-2033, Interim Deficiency Rept Re Clamps on Control Rod Drive Insert/Withdraw Lines Not Providing Axial Restraint. Initially Reported on 831209.Design Mod to Pedestal Support Initiated.Also Reportable Per Part 211984-01-12012 January 1984
Interim Deficiency Rept Re Clamps on Control Rod Drive Insert/Withdraw Lines Not Providing Axial Restraint. Initially Reported on 831209.Design Mod to Pedestal Support Initiated.Also Reportable Per Part 21
PLA-2026, Interim Deficiency Rept Re GE Reactor Mode Switch.Proposed Redesign of Mode Switch by GE Rejected,Based on Results of Testing Conducted at Franklin Inst Research Lab.Alternate Switch Ordered Through Electroswitch.Final Rept by Apr 19841984-01-12012 January 1984
Interim Deficiency Rept Re GE Reactor Mode Switch.Proposed Redesign of Mode Switch by GE Rejected,Based on Results of Testing Conducted at Franklin Inst Research Lab.Alternate Switch Ordered Through Electroswitch.Final Rept by Apr 1984
PLA-2009, Final Deficiency Rept Re Standby Gas Treatment Sys (SGTS) Performance Not as Described in Fsar.Fsar Change Prepared to Indicate SGTS May Be Required to Maintain Secondary Containment Integrity1984-01-0909 January 1984
Final Deficiency Rept Re Standby Gas Treatment Sys (SGTS) Performance Not as Described in Fsar.Fsar Change Prepared to Indicate SGTS May Be Required to Maintain Secondary Containment Integrity
PLA-1990, Final Deficiency Rept Re Isolation of Nitrogen Makeup Sys. Permanent Mod Consists of Rerouting Drywell & Wetwell Nitrogen Makeup Lines to Spare Penetrations.Divisionalized Isolation Valves Will Be Installed1983-12-30030 December 1983
Final Deficiency Rept Re Isolation of Nitrogen Makeup Sys. Permanent Mod Consists of Rerouting Drywell & Wetwell Nitrogen Makeup Lines to Spare Penetrations.Divisionalized Isolation Valves Will Be Installed
PLA-1946, Interim Deficiency Rept Re Bechtel Failure to Accomplish Design Verification of safety-related Power & Control Cables.Bechtel Completed & Documented Required Cable Length Verification & Calculations1983-12-30030 December 1983
Interim Deficiency Rept Re Bechtel Failure to Accomplish Design Verification of safety-related Power & Control Cables.Bechtel Completed & Documented Required Cable Length Verification & Calculations
PLA-1991, Final Deficiency Rept Re Cracks in Pacific Scientific PSA-1 & PSA-3 Snubber Capstan Springs.Caused by Improper Spring Forming.Snubbers Will Be Corrected Prior to Completion of First Refueling Outage.Also Reported Per Part 211983-12-27027 December 1983
Final Deficiency Rept Re Cracks in Pacific Scientific PSA-1 & PSA-3 Snubber Capstan Springs.Caused by Improper Spring Forming.Snubbers Will Be Corrected Prior to Completion of First Refueling Outage.Also Reported Per Part 21
PLA-2000, Interim Deficiency Rept Re Electrical Sys Separation in Multiple Div Pull & Junction Boxes.One Box Identified Containing Redundant Channel C & D Circuits Insufficiently Separated by Approved Barrier1983-12-27027 December 1983
Interim Deficiency Rept Re Electrical Sys Separation in Multiple Div Pull & Junction Boxes.One Box Identified Containing Redundant Channel C & D Circuits Insufficiently Separated by Approved Barrier
PLA-2006, Interim Part 21 Rept Re Improper Relief Valve Settings & Design Pressures & Temps Found in Hpci,Rcic,Rhr,Core Spray & Essential Svc Water Sys.Initially Reported on 831118. Hydrotests Performed1983-12-20020 December 1983
Interim Part 21 Rept Re Improper Relief Valve Settings & Design Pressures & Temps Found in Hpci,Rcic,Rhr,Core Spray & Essential Svc Water Sys.Initially Reported on 831118. Hydrotests Performed
PLA-1987, Updated Interim Deficiency Rept Re Scram Discharge Vol Vent & Drain Valve Waterhammer.Testing & Subsequent Analysis Will Be Completed in Mar 1984.Util Will Submit Final Rept by Apr 19841983-12-14014 December 1983
Updated Interim Deficiency Rept Re Scram Discharge Vol Vent & Drain Valve Waterhammer.Testing & Subsequent Analysis Will Be Completed in Mar 1984.Util Will Submit Final Rept by Apr 1984
PLA-1967, Final Deficiency Rept Re Suppression Pool Temp Monitoring Sys (Spotmos).Initially Reported on 821015.Modified Installation Configuration Tested.Review of Test Results Will Be Completed by End of Mar 19841983-12-13013 December 1983
Final Deficiency Rept Re Suppression Pool Temp Monitoring Sys (Spotmos).Initially Reported on 821015.Modified Installation Configuration Tested.Review of Test Results Will Be Completed by End of Mar 1984
PLA-1968, Final Deficiency & Part 21 Repts Re Final Design of GE 7700 Series 250-volt Dc Control Ctrs.Plant Operating Procedures Revised to Include Methods of Clearing Obstructions as Provided by GE & Exam & Reforming of Draw Out Contacts1983-12-0505 December 1983
Final Deficiency & Part 21 Repts Re Final Design of GE 7700 Series 250-volt Dc Control Ctrs.Plant Operating Procedures Revised to Include Methods of Clearing Obstructions as Provided by GE & Exam & Reforming of Draw Out Contacts
1998-07-09
[Table view]
Category:TEXT-SAFETY REPORT
MONTHYEARML20217A9931999-09-30030 September 1999
NRC Regulatory Assessment & Oversight Pilot Program, Performance Indicator Data
ML17146B1741999-08-0303 August 1999
GL 96-06 Risk Assessment for Sses.
ML20206D3331999-04-27027 April 1999
SER of Individual Plant Examination of External Events Submittal on Susquehanna Steam Electric Station,Units 1 & 2. Staff Notes That Licensee IPEEE Complete with Regard to Info Requested by Suppl 4 to GL 88-20
ML20195B2381999-03-31031 March 1999
Redacted Version for 10CFR2.790 Request for Decommissioning Status Rept for Sses,Units 1 & 2
ML17164A8451998-10-31031 October 1998
SSES Unit 1 Tenth Refueling & Insp Outage ISI Outage Summary Rept.
ML20236N6751998-07-0909 July 1998
Part 21 & Deficiency Rept Re Notification of Potential Safety Hazard from Breakage of Cast Iron Suction Heads in Apkd Type Pumps.Caused by Migration of Suction Head Journal Sleeve Along Lower End of Pump Shaft.Will Inspect Pumps
ML20217Q4891998-04-21021 April 1998
Rev 1 to Draft LDCN 2482, FSAR Chapter 13.4 & FSAR Chapter 17.2 Changes to Support ITS Implementation
ML18026A4931998-03-30030 March 1998
LER 97-007-01:on 971017,entry Into TS 3.0.3 Occurred to Allow Completion of Surveillance Testing of One Channel of Rbm.Caused by Failure of Components in LPRM Output to Rbm. Submitted TS Change Request to Extend LCO Action Statement
ML18026A5401998-02-28028 February 1998
Monthly Operating Repts for Feb 1998 for Susquehanna Steam Electric Station.W/980313 Ltr
ML18026A4891997-11-17017 November 1997
LER 97-007-00:on 971017,TS 3.0.3 Entry Voluntarily Made. Caused by Inadequate Post Maint Testing Following Earlier Work Associated W/Components.Failed Components Repaired, Replaced & Testing Completed
ML18017A2921997-10-28028 October 1997
1997 Nrc/Fema Observed Exercise.
ML17158C1861997-06-0505 June 1997
Proceedings of Intl Topical Meeting on Advanced Reactors Safety Vol II, on 970601-05
ML20140A9661997-05-29029 May 1997
Part 21 Rept Re Ksv Emergency Diesel Generator Power Piston Failure.Caused by Jacket Water in Combustion Chamber. Recommends That Users Verify That Crown Thickness at Valve Cutout Be 100 Minimum
ML18026A4781997-03-28028 March 1997
Rev 1 to Application of Anfb to ATRIUM-10 for Susquehanna Reloads.
ML20137G6261997-03-25025 March 1997
Svcs Part 21 Rept Re Emergency Generators Installed at Zion Station Which Developed Significant Drop in Crankcase Lube Oil Level.Caused by Crack in Liner Wall,Allowing Jacket Water to Enter Chamber
ML20155F7661996-07-25025 July 1996
Partially Deleted Job Number 739619-96, Investigation of E Diesel Breaker Misalignment
ML20155F7491996-07-24024 July 1996
Independent Safety Evaluation Svcs Project Rept 3-96, Investigation of E Diesel Generator In-Operability Event
ML20117G4641996-05-14014 May 1996
Part 21 Rept Re Cooper Bessemer Reciprocating Products,Div of Cooper Cameron Corp,Issued Ltr to Define Utils/Plants Containing Similar Equipment as Supplied on Cooper Bessemer Ksv & Enterprise Dsr EDGs
ML18026A5961996-01-0202 January 1996
LER 95-013-00:on 951119,thermally Induced Pressure Locking of HPCI Valve Occurred Under Bonnet Pressure of 3,000-7,000 Psig.Damaged HPCI Injection Valve repaired.W/960102 Ltr
ML18017A0511995-11-30030 November 1995
Monthly Operating Repts for Nov 1995 for SSES Units 1 & 2. W/951215 Ltr
ML20092H7641995-08-31031 August 1995
Monthly Operating Repts for Aug 1995 for Susquehanna Ses
ML17158A8771995-08-15015 August 1995
Exercise Manual.
ML17158A8061995-07-14014 July 1995
Books 1 & 2 of ISI Outage Summary Rept SSES Unit 1 8th Refuel Outage.
ML18017A0461995-07-0707 July 1995
LER 95-008-00:on 950609,shift Average Licensed Core Thermal Power Was Exceeded.Caused by Failed Instrumentation Drift. Repaired & Recalibrated Subject Instrumentation
ML17164A6631995-04-11011 April 1995
Impact of Extending T-10 AOT from 3 to 7 Days.
ML17164A5871995-01-31031 January 1995
Monthly Operating Repts for Jan 1995 for Susquehanna Ses
ML18026A5351994-10-31031 October 1994
SSES Unit 1 & 2 MSIV Leakage Alternate Treatment Method Seismic Evaluation. W/One Oversize Drawing
ML17158A4821994-08-23023 August 1994
ISI Outage Summary Rept Unit 2 6th Refueling Outage, Books 1 & 2 of 2
ML17158A2391994-04-0505 April 1994
Books 1 & 2 of SSES Unit 1 Seventh Refueling & Insp Outage ISI Outage Summary Rept.
ML18017A2701993-12-31031 December 1993
PP&L Annual Rept 1993.
ML17158A2651993-12-31031 December 1993
Allegheny Electric Cooperative,Inc Annual Rept 1993.
ML17158A1631993-12-0909 December 1993
Remote Indication of Spent Fuel Pool Level & Temperature.
ML18026A4281993-08-16016 August 1993
PP&L Response to NRC Concerns Re Loss of Spent Fuel Pool Cooling Following Loca,Sses,Units 1 & 2.
ML18026A4261993-06-0909 June 1993
LER 90-007-01:on 900705,primary Power Supply to RPS a Power Distribution Panel Lost When One Electrical Protection Assembly (EPA) Breaker Tripped.Epa Logic Cards Reviewed & RPS Power Supply Will Be redesigned.W/930609 Ltr
ML17157C2441993-02-28028 February 1993
Monthly Operating Rept for Feb 1993 for Susquehanna Steam Electric Station,Units 1 & 2
ML18017A2031993-02-0101 February 1993
Books 1 & 2 of Unit 2 Fifth Refueling & Insp Outage,Isi Outage Summary Rept.
ML20044C2741993-01-31031 January 1993
Corrected Monthly Operating Rept for Jan 1993 for Susquehanna Steam Electric Station,Unit 2,consisting of Info on Unit Shutdowns & Power Reductions
ML17157C3691992-12-31031 December 1992
PP&L Annual Rept 1992.
ML20056C3941992-12-31031 December 1992
Allegheny Electric Cooperative,Inc Annual Rept 1992
ML18017A0421992-12-14014 December 1992
Suppl to 921127 Part 21 Rept Re High Air Concentration in Reactor Bldg Making Area Uninhabitable for Retrieving Air Filters,Per NUREG-0737,Item II.F.1.Util Current Position Re Fuel Pool Cooling Issues Contrary to Reg Guide 1.3
ML18026A2481992-11-27027 November 1992
Part 21 Rept Re Substantial Safety Hazard in Design of Facility for Loss of Normal Spent Fuel Pool Cooling
ML18026A4231992-11-17017 November 1992
LER 92-016-00:on 920416,discovered That Existing Analysis for Two Spent Fuel Storage Pools Did Not Reflect Current Fuel Design & Plant Operation.Caused by Failure to Modify FSAR Analysis.Fsar Will Be revised.W/921117 Ltr
ML17157C1421992-10-21021 October 1992
Engineering Assessment of Fuel Pool Cooling Piping EDR-G20020.
ML17157C1411992-08-31031 August 1992
Loss of Fuel Pool Cooling Event Evaluation.
ML17157C1401992-08-31031 August 1992
Review of Fuel Pool Cooling During Postulated Off-Normal & Accident Events SSES Units 1 & 2.
ML20082C4941992-08-14014 August 1992
Evaluation of Unit 1 & Unit 2 Derating of Power Cables in Raceways Wrapped W/Thermo-Lag Matl
ML17157C1381992-07-27027 July 1992
Safety Consequences of Boiling Spent Fuel Pool at Susquehanna Steam Electric Station.
ML17157B9331992-07-24024 July 1992
Sixth Refueling & Insp Outage Inservice Insp Outage Summary Rept, Books 1 & 2
ML20097D4681991-12-31031 December 1991
Pennsylvania Power & Light Company,1991 Annual Rept
ML18017A0391991-07-26026 July 1991
LER 91-010-00:on 910628,RWCU Isolated on Two Occassions Due to Actuations of Steam Leak Detection Instrumentation. Caused by Design Deficiency & Elevated Ambient Penetration Room Temps.Temp Modules replaced.W/910726 Ltr
1999-09-30
[Table view] |
Text
Revision1JN4'~'-'0'8012FINALREPORTONSPOT-WELDED STRUTSFORSUSQUEHANNA STEAMELECTRICSTATIONUNITS1AND2Preparedby:Checkedby:Approvedby:BECHTELPOWERCORPORATION SanFrancisco, California September 29,1978December29,197U(Revision 1)(P23-9)o80102$
0le' Revision1~JN4>"-">OJSG'32TABLEOFCONTENTSSectionTitle~Pae1.02.0PurposeSpot-welded Struts3~0Background 4'Deficiency anditsSafetyImplications 5'Immediate Action6.0TestProgram7'Technical Evaluation ofDeficiency
8.0 Corrective
Action109.0RepairMethods10'Conclusion 14ATTACHMENTS (P23-9)TestReportby'Pittsburgh TestingLaboratory'est ResultsSpecifications
- TheAttachments werepreviously transmitted viaPLA-295datedOctober9,1978andarenotforwarded withthisreport.
Revision11'PURPOSEThepurposeofthisreportistoprovidefinaldataand.information asrequiredby10CFR50.55(e)(3) subsequent tothenotification ofareportable deficiency.
Thesubjectdeficiency isassociated withspot/resistance weldinginstrutmaterial.
2.0SPOT-WELDED STRUTS2.1StrutsBasicstrutsectionsarelightgage(thickness varyingfrom0.105to0.109inch)channelsmanufactured bycoldformingmildsteelstrip.Thesechannelsec-Vtionsareconnected toeachotherinvariousconfigura-tionssuchasback-to-back, back-to-side, orside-to-side byusingaweldingprocesscommercially knownasspot-weldingorresistance welding.Thechannelsectionsandbuilt-upsectionsusedonSusquehanna projectareeithermill-galvanized orhot-dipgalvanized afterspot-welding andaresuppliedbyUnistrutCorporation, Wayne,Michigan; PowerStrut,DivisionofVanHuffelTubeCorporation, Warren,Ohio;andB-LineSystemsIncorporated,
- Highland, Illinois.
Thesewereprocuredasstandardoff-the-shelf, itemswithnoformalQualityAssurance.
Variousconfigurations usedonSusquehanna aregiveninFigureI.Strutmembersareusedinfieldfabricated supportsforelectrical
- raceways, HVACductsandinstrumentation
>e4r-'69BQj2..
lines.Thegoverning documents aredrawing8856-E-53 forelectrical
- raceways, Specification 8856-M-323-C forHVACductsandDrawing8856-JG-16 forinstrumenta-tion.Thesupportsaredesignedinaccordance with'Specifi-cationfortheDesignofCold-formed SteelStructural Members'1968 Edition),
published byAmericanIronandSteelInstitute.
Thespot/resistance weldingprocessconsistsofpassinghighcurrentthroughthethicknesses ofadjoining platesresulting inmetal-to-metal fusion.Thequalityofaspotweldisdependent onmanyvariables suchaspres-sureontheelectrode tips,finishofthematerial, presenceofimpurities onthematerial, build-upofzincandothercontaminents ontheweldingelectrodes, contactbetweenjoiningsurfaces, voltageandamperage.
Therefore, unlesstheseparameters arecloselymoni-toredandcontrolled, theresultmaybeinadequate fusion.3.0BACKGROUND SincetheuseofstrutmaterialbeganontheSusquehanna Pro-ject,therewerethreeisolatedinstances whentheadjoining Fchannelsseparated duringhandlingorassembling.
Thesememberlengthswererejected.
(P23-9) evision1.)(z-r=.E8612However,inrecentmonthstherehavebeensignificant in-stancesonothernuclearprojectswhereinadequate fusionwasobservedattheweld.spots.Asaresultofth's',onMarch25and26,1978,Bechtelfieldengineering personnel performed aninspection onUnistrutmemberP-1004A,Power-strutmemberPS-3022andB-LinememberB22-X.Thetestedmemberswerepartofinstalled electrical racewayandHVACductsupports.
.Themethodofinspection consisted of'sounding'he memberswithaballpeenhammertodetectseparated spotweldsandverification oftheseparation byinsertion ofacardbetweenthemembersatthespotwelds.Theinspection indicated ahighincidence ofspot-welds withinadequate ornofusion.Therefore, ProjectQualityAssurance (QA)issuedManagement Corrective ActionReport(MCAR)1-23onMarch28,1978.4.0DEFICIENCY ANDITSSAFETYIMPLICATIONS Basedupontheresul'tsoftheinspection asdescribed inSection3.0,itwasdetermined that:a.Thedeficiency isrelatedtospot-welding technique and/orprocedure.
b.Thequalityofthespot-welding isindeterminate, withoutfurtherinvestigation.
Variouscombinations andconfigurations ofchannelstrutshavebeenusedinthesupportsystems.Individual members(P23-9) vision10.8012havebeendesignedascomposite sectionsforwhichthecon-nection(spot-welding usedinthisinstance) betweenadjoin-ingchannelsisreliedupontocarrythepostulated loadswithinestablished designmargins.Thus,inadequate fusionatthespot-welding mayresultininadequate
- strength, andmayadversely affectthesafeoperation oftheplantunderdesignloadingconditions.
5.0 IMMEDIATE
ACTIONA'Hold'asimposedonfurtherinstallation ofmemberP-1004Aoritsequivalent unlessthememberwasstitch-weldedtodevelopequivalent designstrengthofthespot-welding.6.0TESTPROGRAM6.1General.Althoughitwasdetermined thatadeficiency existedinsomespot-welded members,theextentofthede-ficiencywasunknown.Sothefirststepwastoes-tablishthescopeoftheproblem.Sincethereisnopractical nondestructive methodforexamining thesound-Inessofspotweldsintheerectedmaterial, itwasde-cidedtoinitiateadestructive testprogram.6.2BasisofTestProramTheunderlying approachisdescribed below.(P23-9)
Resion1Jw4'r-I,:-"Q.Q'lR a.Obtainrepresentative samples,selectedatrandom,fromthe'nstalled andstockmaterialforallshapesandmanufacturers.
b.Performdestructive sheartestonthesamplestoobtainfailureloads.c.Analyzethetestresultsstatistically foreachshapeandmanufacturer tocomputecorresponding expectedstrengthperspot-weld atacertainconfidence level.6.3~samlesSampleswereobtainedbyBechtelfieldengineering personnel andsenttoarecognized testinglaboratory.
Samplesweretypically 6"longcontaining twospot-welds.
Forthestockmaterial, twosampleswereobtainedfromeach20'-0"lengthandonlyonesamplefromanygiveninstalled memberselectedatrandom.Forthcinstalled
- material, generally onesamplewasobtainedforevery100feetoftheinstalled quantity.
6.4~TestisTestingwasdonebyPittsburgh TestingLaboratory (PTL)inPittsburgh, Pennsylvania.
Testmethodandprocedures arefullydescribed inPTL'sreport.(SeeAttachment A).(P,23-9)
Revision16.5Statistical Analsis>e4-isgasp:g.pBaseduponthetestresults,histograms wereplottedforeachshapeandmanufacturer.
Meanandstandarddeviation werecomputedforeachcase.Thetestresultsgenerally followthenormaldistribution.
Theexpectedfailureloadperspotweldwasdetermined byusingthemeanofthefailureloadbaseduponthetestresultsandsubtracting oneandahalftimesthestandarddeviation.
Thisapproachprovidesmorethan90%confidence levelfortheexpectedfailureload.Baseduponabovecriteria, theexpectedfailureloadswerecomputedandaregiveninTableI.7.0TECHNICAL EVALUATION OFDEFICIENCY 7.1GeneralThetechnical evaluation inthissectionislimitedtoallstrutmembersinstalled and/oratthejobsitewhicharenotfabricated.
7.2DesinCriteriaandTheoretical Considerations AISIspecification specifies allowable shearstrengthperspot-weld tobeequalto1.65kipswithafactorofsafetyof2.5for0.109inchthickness.
Thisal-lowableshearisbasedupon"Recommended Practices (923-9)
Revision1Jgg-(cg,gg.Q'j'f forResistance Welding,"
AWSC1.1,byAmericanWeldingSociety.Basedonthiscriteria, thefailureloadforaspotshouldbeover4,000pounds.However,inlightoftheproblemassociated withspot-welding, itisnecessary toassessbasesofcoderequirements andevaluatestructuraladequacyoftheinstalled materialwithoutcompromising thebasicdesignphilosophy.
Theconnection providedbyspotweldsbetweenadjoin-ingchannelsectionsisreliedupontomaintaintheintegrity ofthebuilt-upsections.
Thecalculated shearinaspotweldinamemberdependsuponmanyvariables suchasloading,sectional properties, endconditions andifthememberisusedasabeam,brace,columnortie.Theallowable shearof1.65kips/spot specified bythecodeistheupperlimitfordesigning purpose.However,fromtheevaluation pointofview,itismorerealistic toconsideractualmaximumdesignshearcal-culatedindividually asrequiredforeachshape.Sec-ondly,forthestrutmaterial(Fy=33k.s.i.)theallowable bendingstress(Fg)percodeis20k.s.i.for0.105inchthickness.
Therefore, thefactorofsafetyforthebendingstressisconsidered tobe1.65whileforthespot-welds, itis2.5,whichisratherhigh.Reasonforthiscouldbeattributed tomanyvariable, w7(P23-9)
Revision1Ju4ra098012affecting theweldstrength.
Forthematerialinques-tiononSusquehanna, anextensive testprogramhasbeencarriedoutandexpectedfailureloadsforeachshapearewelldefined.Therefore, itisreasonable toas-sumethatafactorofsafetyof2.0forspot-welds, whichisstillhigherthanthefactoryofsafetyforbendingofthestrutmaterialwouldstillbeadequateandconsistent withthebasicdesignphilosophy.
73Thedesignofframingmembersinthesupportsystemisbaseduponallowable shearof1650lbs.perspotweld.Therefore, tomaintainaminimumsafetyfactorequalto2.0,theexpectedfailureloadmustbe3300lbs.orgreater.7.3.1Thestrutsectionswiththeexpectedfailureloadequaltoorgreaterthan3300lbs/spotweld,areconsidered tobestructurally adequate.
7.3.2However,fortheothersections, furtherevaluation isnecessary.
Designloadsonthesupportsystemsaregovernedbymanyconsiderations suchastypeofsupport,structure, elevation, etc.Forindividual mem-bersinasupport,designshearforcesaddition-allydependuponifthemembersareloadedflex-urallyoraxially.Etisnotedthatforflexuralmembers,shearforcesaregenerally high.
Revision1JhNg<cg>GOjpFortheearlierinvestigation, a5'-0"longmember'sup-portinguniformly distributed loadwasconsidered tobearepresentative caseforvariousloadingconditions, andmembershapes,andcomparison wasmadebetweencom-puteddesignshearsandexpectedfailureloads.However,inthefinalanalysis, actualdesignshearswerecomputedinindividual membersforallsupport~typesinvariousbuildings andatdifferent eleva-tions.Theseshearvaluesvaryconsiderably; therefore, theexistingmembers,whichmaybeadequateatacertainlocation, mayneedstrengthening elsewhere depending ontheaforementioned variables.'n anycase,afac-torofsafetyof2.0hasbeenmaintained.
7.4~SummarBaseduponafactorofsafety,of2.0,allshapesaregroupedinthreecategories.
CateorIUnistrut:
P-5501,P-1001C,P-3301,P-1001AP-1001C3Powerstrut:
PS-151,PS-202Theseshapesarestructurally adequateandneednorepair.
CateorIIUnistrut:P-1001,P-5001Powerstrut:
PS-201,PS-101,PS-204PS-3080B-Line:.B-12AThesesectionsareconsidered deficient atcertainlocations andneedtoberepairedasrequired.
CateorIIIUnistrut:P-1004APowerstrut:
PS-3022B-LineB-22X,B-11AAllmembersofaboveshapesaretoberepaired/
strengthened toprovideshearconnection capacityequaltotwicethedesignstrengthrequired.
8.0 CORRECTIVE
ACTION8.1GeneralCorrective actionsaregroupedinseveralcategories.
Eachcategoryandcorresponding actionisdescribed below.8.2Installed andStockMaterial8.2.1Powerstrut PS-3022,IUnistrutP-1004AB-LineB-22X.Basedupontheinspection byBechtelfieldengineering personnel, allmaterialofthis-10-(P23-9) evisionlconfiguration wasdeemedtobedeficient, andwillbecompletely repairedwithouttakinganycreditfortheexistingspotwelds.8.2.2B-LineB-11A.Installed andstockquantityforthisshapewassmall;therefore,.
nosampleswereobtained.
Intheabsenceofanytestdataontheexistingspotwelds,thissectionwillberepairedtodeveloprequireddesigncapacitytomeetthedesigncriteria.
8.2.3Powerstrut:
PS-151,PS-202Unistrut:
P-5501,P1001G,P-3301,P-1001A,IP-1001C3Baseduponthetechnical evaluation inSection7.0,existingspot-welding isadequateandwillperformsatisfactorily underdesignloads.Therefore,nofurtheractionisdeemedneces-sary.8.2.4Powerstrut; PS-201,PS-101,PS-204,PS-3080Unistrut:
P-1001,P-5001IB-Line:B12A-11-(P23-1/1)
Revision1igu7.0912Thesemembersdonotmeetthedesigncriteria, therefore,adetailedre-analysis andredesignhasbeenperformed tocomputerequiredadditional strengthanddesigndrawingshavebeenpreparedtoshowthenecessary repairdetails.There-quiredrepairwillbeperformed ontheinstalled andstockmaterial.
Oncompletion oftherepair,thestrutmaterialwillsatisfythedesigncri-teria.8.3StrutMaterialtobeReceivedintheFutureUntilnow,thestrutmaterialwasprocuredasastan-dard'offtheshelf'tem.
However,inlightoftheproblemexperienced withthespot-welding, anewspeci-.fication8856-C-92 (seeAttachment C)wasdeveloped forprocurement of,allspot-welded strutsinthefuture.TheresultsofthetestingbyPTLpositively indicatethatthespot-welds onaplainmaterialhavemuchhigherstrengththanspot-welds onmill-galvanized material.
Therefore, thespecification stipulates thatstrutmaterialtobecoatedafterspotwelding.
Inadditiontothis,toprovideareasonable assuranceofattaining thedesignstrength, thesupplierisre-quiredtointroduce adestructive testingprogramontheproductionsamplesandnomaterialwillbeshippedtoSusquehanna jobsiteunlessitmeetstheacceptance
.criteria.
Thisactionshouldpreventtherecurrenceofthisprobleminthefuture.(P23-1/2)
Revision19.0REPAIRMETHODSN4'Kid+Q3,+r,'.
1GeneralConstruction hasbeenprovidedtheoptiontoselectanyoneofthefollowing methodsonacase-by-case basis.9.Thismethodistoreplacethedeficient materialwithnewmaterialtobeprocuredperSpecification 8856-C-92 (seeAttachment C).9.3Mechanical Fasteners Secondmethodistoprovide1/4"dia.self-drilling andself-tapping metalscrewstoobtainrequiredshearstrength.
These,screwswillbeprocuredperSpecification 8856-C-91 (seeAttachment C).Inordertoassurestrengthrequirements forthescrews,itisrequiredtoperformadestructive sheartestonsamplesandeachlotmustmeettheacceptance criteria.Inadditiontoself-drilling andself-tapping screws,othermechanical fasteners arebeingconsidered suchaspop-rivets orclamps.Ifthesearedetermined tobetechnically acceptable, theywillbeusedasalternate tothescrews.-13-(P23-1/3)
'
ision19.II~VeldknThirdapproachistoprovideintermittent
.stitchweldingatthejointbetweenchannelsand/orchan-nelandsideplate.
10.0CONCLUSION
Oncompletion oftherequiredrepair/replacement oftheexistingspot-welded strutsdetermined tobedeficient, theexistingsupportsystemswillbestructurally ade-quatetosatisfythedesignrequirements.
- Secondly, pro-curementofnewspot-welded strutmaterialpernewspec-ification (seeAttachment C),willprovideadequateas-suranceofpreventing therecurrence ofthisprobleminthefuture..-14-(F23-1/4)
Hevislon1TABLE1EXPECTEDFAILURELOADS~FE82'80C99480StandardExpectedFailureLoadMeanDeviation
=A-1.5BMeuufactur erMember(1bs)(1bs)(lbs)RemarksUnistrut(A)(B)P-10014140-1213P-550154991229P-50014357-,1072P-1001C53861033P-3301'4651025P-1001A4192554P-1001C3,5186 629232136563837392833614243Cat.IICat.ICat.IICat.ICat.ICat.ICat.I(Backtoback)P-1001C351264584439Cat.IPowerstrut (Backtoside)PS-2014418,1194PS-1515533892PS-1013855782PS-20441502233PS-308041261252262741952682801Cat.IICat.ICat.IICat.IIICat.II(Backtoback).PS-30804666(Backtoside)PS-2025783B12A356515111317240039501590Cat.IICat,ICateIINote'.1.Abovenumbersinthetablearebasedupononespotveld.2.Forexplanation ofRemarks"column,refertosection7.4.3.ForshapesinFigure1andnotintableabove(i.e.thoseinCategoryIII),refertosection7.4.(P23-10)
FIGURE1STRUTSHAPESANDIDENTIFICATION Revision1~Shae0UnistrutP-5001Powerstrut PS-101B-LineB-11A~ShaeRUnistrutP-5501Powerstrut PS-151B-LineB-12A~ShaeKUnistrutP-1001Powerstrut PS-201.~ShaeNUnistrutP-1004APowerstrut PS-3022B-Line,B-22X3~haeNUnistrutP-1001C3Powerstrut PS-3080~ShaeLUnistrutP-1001CPowerstrut PG-204~Shae0UnistrutP-1001APowerstrut PS-202ShauePUuiattutP-3301
