Executive-organization-method-EN-焦化系統(tǒng)通廊鋼結(jié)構(gòu)施工方案

MEASURESFORSTEELstructuralFABRICATION

category:COKINGPLANTSECTION

Subcategory:J1,j2，j3,j4，J5Beltconveyergallery

PARTI:INTRODUCTION

I。

OVERVIEWABOUTBELTCONVEYERGALLERYSTRUCTURALSYSTEM:

J1，J2，J3，J4，J5beltconveyergallerystructuralsystemistheitemofThaiNguyenSteelandIronCorporation2ndstageexpansionproject.BeltconveyergallerysteelstructureisdesignedbythePrincipalContractorChinaMetallurgicalGroupCorporation（MCC)andassigntothissubcategoryforSubcontractorisThangLongFerrousMetallurgyJointStockCompany。Thissubcategoryincludesthefollowingsections：

1。J1beltconveyergallerysteelstructurelinkingtheJ2transportstationwithJ3transportstation。

J2beltconveyergallerysteelstructurelinkingtheJ3transportstationwithcokecuttingroom.

J3beltconveyergallerysteelstructurelinkingthecokecuttingroomwithJ4transportstation.

J4beltconveyergallerysteelstructurelinkingtheJ4transportstationwiththecokescreeninghouse。

J5beltconveyergallerysteelstructurelinkingthecokescreeninghousewithG2transportstation.

SubcategoryofbeltconveyergallerysteelstructuresystemisdesignedwithsteelcolumnsystemwhicharemanufacturedfromhotrolledsteelgeometricfontsizeH.Structureofrackingplatformisusedtypesofhotrolledanglesteel,steelbeamsystemsupportingroofisusingcombinedsteelgeometricfontsizeI。Sub-beamssystemsupportingthefloorusinghotrolledsteelshapeI，U。。.。PurlinroofsystemusingsteelshapeC.。。Flooringsheetandstairsontheconveyorusing6mmanti—slipreligious。

Thissub—categoryisdesignedtouseplanofstructuralofhotrolledsteelcolumnlinkingstabilitybracingandrackingplatformsystemrunningalongtheconveyorgallerysothecolumnstructuresandtrussareappliedsimilarproductionprocesses.Sointhisconstructionmethod,wejustdiscussthemeasurestoproducesteeltruss’sframestructures.

II。SIZEANDSTRUCTUREOFTHEITEM。

1.Describethesizeofthebeltconveyergallerystructuralsystem(J1-J5）：

J1beltconveyergallerysteelstructurehaslengthof10。56m.Trusssystemisarrangedstartingfromcos-0.181m.Andalongthedesignslopeto+2，894m.Thewidthofthesteeltrusssystemis3。4m。Theheightofthetrusssystemis2.5m。

J2beltconveyergallerysteelstructurehaslengthof54。50m。Trusssystemisarrangedstartingfromcos+0600mandalongthedesignslopeto+9,676m.Thewidthofthesteeltrusssystemis3。4m。Theheightofthetrusssystemis2.5m.

J3beltconveyergallerysteelstructurehaslengthof124.00m。Trusssystemisarrangedstartingfromcos+1219mandalongthedesignslopeto+23，779m。Thewidthofthesteeltrusssystemis3。4m.Theheightofthetrusssystemis2。5m。

J4beltconveyergallerysteelstructurehaslengthof20。35m。Trusssystemisarrangedstartingfromcos+21，156mandalongthedesignslopeto+26，715m。Thewidthofthesteeltrusssystemis3.4m。Theheightofthetrusssystemis2。5m。

J5beltconveyergallerysteelstructurehaslengthof12.666m.Trusssystemisarrangedstartingfromcos+5007mandalongthedesignslopeto+6，710m.Thewidthofthesteeltrusssystemis3.4m。Theheightofthetrusssystemis2.5m.

Basedonthedesigndrawing,whichwerehandedbythePrincipalContractortoSubcontractor,wedividedintothefollowingtypesofcomponents:

SteelcolumnsStructuresupportingthemaintrussstructure：

-Columntype1(JZ4)hascrosssectionofemptycolumnwithwidthof3.4mandheightof14。52m.MainbarbysteelH300*305，bracingbarbysteelU16,andL75—L100.

—Columntype2（JZ2/3）hascrosssectionofemptycolumnwithwidthof3.4mandheightof10。35m。MainbarbysteelH488＊300，bracingbarbysteelU18,andL56-L125。

-Columntype3(JZ2/3）hascrosssectionofemptycolumnwithwidthof3。4mandheightof19。55m。MainbarbysteelH700*300，bracingbarbysteelU18,andL56—L125。

—Allthecolumnshavelength>12mwillbedividedintosmallercomponentswithlength<=12mandallareproducedintheplant,thencombinedandconnectedintheconstructionsite。

B.J1-J5beltconveyergallerysteelstructure：Width3.4m;Height2。5matotallengthiscalculatedasthedesignslopeis:222.076m。

-Rackingplatform（HJ1—HJ8)hasstructureofanglesteeltrussformat：Height2。5m,Length31.2m（max）。Thebarinuppertrussandthebarinbellowtrussisusedhotrolledsteel2L100-2L130.Thewebbarsusehotrolledsteel2L63—2L90。

—BottomfloorofconveyorsarehorizontalbeamssupportconveyerusingsteelI18,verticalbeamssupportconveyerusingsteelI16，auxiliarybeamsusingsteelU8.Flooringsheetonthebeltconveyorgalleriesandstairsuse6mmanti—skidsteelplate.

-Steelstructurecoversbeltconveyorgalleriessystem:Theframeworkisusedtocoverusingcombinedsteel。BracingoftheframeusinganglesteelL56*5，thestructuresupportingthereligiousroofusingC200cold-rolledshapesteel，thestructuresupportingthereligiouswallusingC120cold-rolledsteel.

-Alltheframeshavelength〉12mwillbedividedintosmallercomponentswithlength〈=12mandareproducedattheplant,thencombinedandconnectedintheconstructionsite.

PARTII:

PREPARATIONOFFACILITIES,ENGINEERINGSUPPLIESANDMATERIALS

FORSTEELSTRUCTURALFABRICATIONOFBELTCONVEYORGALLERY

I.FACILITIESENGINEERINGSTEELPRODUCTION。

TheentiresteelstructureoftheitemsteelstructuresupportingbeltconveyorgallerysystemJ1toJ5aremanufacturedatfactoryofThangLongFerrousMetallurgyJSCinMyHaoDistrict-HungYenProvince.

Thestructuralwithweight≤5。000kgandlength≤20mareproducedinfactories。Thestructuralwithweight〉5000kgandlength〉30mareproducedoutsidetheprocessingofsteelstructures.

Ourplantincludesfactorysystem,technicalstaffandskilledworkersequippedwiththemodernequipmentandmachinerytoproduceproductsmeetingthetechnicalrequirementsofdesignsandcurrentstandards.Equipmentsforproductioninplantsisasfollows：

AProcessingequipmentembryos

1.Hydrauliccutterbutflatproduction（Imported） ： 01

2。CNCembryoscutter(Imported） : 02

3.Punching-and—shearingmachine ： 01

4。Hydraulicpressmachine300T—PPN31200 : 01

5。Steelcutters ： 01

B.Mechanicalequipment

1.3-axiswindmachines : 01

2。U—millmachine : 01

3.LatheT750,T823 ： 01

4.Automaticdriftingmachine : 01

5.Large—diameterdrillZ3050x16 : 01

6.Twostonegrinder : 02

7。Handforever：05

8。Drillingmachine ： 01

C。Weldingequipment–bending

1.

AutomaticWeldingMachine2burners : 01

2.

Semi—automaticweldingmachine ： 03

3.

MachinefittingcombinationsH-beamsautomatically : 01

4。

Wingbendingmachine : 01

5。

Ta350CO2weldingmachine–Win : 05

D.Cleaningandpainting

1。

Bogocompressors : 01

2。

Sandblastingmachine ： 01

E.

Transportequipmentlifting

1.

Q=10toncrane : 04

2。

Fork—lifttruck:01

F.

Testequipment

1。

EquipmentandtestkitsKCS ： 01

2.

Coatingthicknessmeasurement：01

3。

Panme,gripsize

G。

Equipmentandconstructionmachineryatconstructionsite

1.

Welder ： 02

2。

Generators ： 01

3。

Ironcuttingmachines ： 01

4.

Machinesforconstructionother

II。

HUMANresourcesforSTEELstructurePRODUCTION.

TotalnumberoftechnicalworkersofthefactorywentintoproductionofsteelstructuresforCokebeltconveyorgalleriesto94peopleatitspeak.

Ofwhich：

1.

Welder:25workers

2。

Themeddetailsfixtures:15workers

3。

Mechanistskilledmanufacturinggrade4/7ormore：05workers

4.

Turner：02workers

5.

Electrician：02workers

5。

Coldassemblyworkers：15workers

6。

Theotherworkersforproduction:20workers

7。

Technicalengineeringstaffforproduction:10people

III.

PREPARATIONMATERIALS,MATERIALSTEELPRODUCTION.

1。

Steel:Alltypesofsteelinproductionofsteelstructurestoensurethenewsteel,stainlesspitting,nowarping。

Steelmusthaveaclearorigin，musthaveaqualitycontrolcheckofeachtypeofbatchproduction。

Aftertheinvestment，supervisionconsultantstoagreetotestforsamplingqualitycontroltoensurethenewsteelwasputintoproduction。

TheentireproductionofsteelforbeltconveyergallerysteelstructureisQ235BsteelwhichmadefromChinaorothersteelwithequivalentspecifications。

2。

Weldingmaterials:weldingmaterialsofchoiceforelectricweldingmethodaccordingtoautomaticweldingandmanualwelding。

a）Manualwelding：AttherequestofdesigninginweldingofQ235Bsteelstructure,usingE43weldingrodsofChina。TypesofweldingrodshasthesametechnicalfeaturesofJ421weldingrodofVietnameseGermanWeldingCompany，F(xiàn)S-E421andFS—E422ofthecompany‘sHuuNghiweldingandconstructionofVietnam’smechanicalproduction.

b)Automaticwelding：WhenweldingsteelstructureswithsteelQ235AandQ235BusingweldingwireandweldingcompoundH08EH08AorequivalentweldingwireandweldingcompoundFS-HW08A,HF-402。

3。ChoosePaint：

-EpoxyPrimer,EpoxyintermediatepaintandcoatingofPUpaintofmanufacturersinVietnamwasacceptedbytheInvestorandMCC(HanoiGeneralPaintCorporation/JotunVietNam/Interpaint/Chugoku.。。）withappropriatequalitymeetingtherequirementsoftheproposeddesign.

PARTIII：

STEELFABRICATION

A-GENERALPRINCIPLES

FabricationofsteelstructuresforbeltconveyergallerystructuralsystemcomplieswithconstructionstandardsandacceptanceofGB50205—2001,steelstructuralweldingstandardJGJ81-91,205—83China'smanufacturingstandardsandstructures

170-8920TCN—steelofVietnamasfollows：

a，Steelstructureandtexturefontaneltiounon—standardpartismanufacturedaccordingtodesigndrawings,detaileddrawingsofcomponentsthatareavailableforapprovalandpromulgation。

b,Whenprocessingusingadvancedmethods，inaccordancewiththerequirementsoftechnologyandstrictcontrolofthestages。

c，Materialsusedforprocessingandmanufacturingtoqualityandnumberofsteelgradesinaccordancewithdesignrequirements。

d,Fortheparticularsteelcomponents，inadditiontogeneralprovisionsalsocomplywithspecificregulationsforsteelmaterialsofthatstructures。

e，Requirementsforsteelandweldingmaterials：Allthesteelintothemanufacturingtobetestedmuscleandphysicallybythelegalunit’sperformance.

Weldingrod，weldingwireandweldingcompound’squalitycertificatesshouldcallthemanufacturertoprovide,priortousetocheckquality.

f，Othermaterials:

Bolts-linktypemusthavethecertificate,thequality.

Anti-rustpaintandprotectedbypaintarespecifiedaccuratelyasthedesignofpaintacomponentortwocomponents,thelevelofcleaningandcoatingthicknessofeachlayer.

B—MANUFACTURINGPROCESSOFSTEELCOMPANY

Researchdesigndrawings,constructiondrawingsmade

Inspectionandapprova/Check,Approval

Updemandformaterials

Purchaseofsuppliesbyprojectrequirements

Checkinputs

Returnprovider

No.

Reach Okreached

Impression,bycuttingembryodrawingshavebeenapproved

Flatstraightening,preparingjointcombineddetails

Inspectionanddocumentation

Detailedfittingcombination

consortiumweldingafterdetailshavebeencombined

Straighteningwingdetailafterwelding

Perfectfittingassemblies

Inspectionanddocumentation

Weldingcompletedetails

Straightening,flat,heated,groundfix

Inspectionanddocumentation

Surfacecleaningproducts

Inspectionanddocumentation

Paintproducts

Inspectionanddocumentation

Lastinspection.

Makingrecordsofcompletedtests

Publictransporttoconstructionsite

C-Steelstructuremanufacturing

I.Billetprocess(billetforming，markingandcutting）

I。1.Formingandmarking：Beforeformingandmarking,steelsurfacemustbecleanedsothatthereisnogreaseordust.Steelmustnotberustyandabscessed。Workerwhoisinchargeofforming，markingmustbeskilledandwell-trainedexperiencedandabletounderstand，detaildesigndrawing.Superviseengineermustpopularizemanufacturingoartstechnologyandinstruetmarkingworkdertomakearedundancyincaseoftheshrinkageincutting,weldingandchamfering.Theredundantindexofbilletisexecuted4。1。2，4.1。3，4.1.5,4.1。6oftheChineseGB50205-2001standardorVietnamese20TCN170-89standard（table4vμtable7).

Toolsforformingandmarkingare：steelpen,paranecalipersquare，iron-sheetmeasuringtape,setquare.

I。2。Billetcutting：

2。1.Cuttingbilletbyheatingmethod:Duringthecuttingprocess,tempermustbestableinordertoreducethebilletwarping.Temperatureatthecutoffpointshouldbecontrolledfrom9000Cto10000Csothatthecuttinglineisflatandnotburneddueandthereisnosteelslagatlowtemperatureinordertoreducethelaborcostforthebilletcleaningprocesstochamfering.

Meansandtoolsforbilletcuttingbyheatingmethodareincluding:Gas–oxyplane-shearingmachinemadeinChina，KEROIgas-oxyplate—shearingmachinemadeinJapan..

2.2.Beveled：Allthebutt-weldingforpartswiththebilletthickness≥8mmshouldbechamferedbymachineorautogenouscuttingmachine.Toleranceofchamferingisexecutedbaseontable4.3.2standardGB50205—2001ChinesestandardorAWSD1.1standardonpage11。Table5appliestoVmanualweldingjoint。

2.3Billetstraighteningbeforejiggingwelding：

—Methodofstraighteningcomponentsmadebystraighteningmachinededicatedstructuresforhot—rolledstructuralsteelandcombinedweldingsteel。Manualstraighteningmethodforstraighteninghot—rolledcornersteelcomponentsandothercomponentswhichhavecomplexsizeandbeamstraighteningmachinefails。

—Theremustbenodimplesonsurfaceofparts，depthofcastmarksonsurface0。5mmafterstraighening。

-Theallowancetolerancetableafterstraighteningsteelmaterial。

No。

Category

Diagram

Allowancetolerance(mm）

1

Partialsmoothnessoftheplate

t≤14

t≥14

1000

t

Tolerancerange1000mm:

1,5

1,0

2

Theheightoftheformsteel’sbow(f)

f

1/1000

5mm

3

b

Verticalstraightnessofanglesteel（Δ）

Δ

Δ

b

Δ=b/1000

4

b

TheslopingofsideedgeofUshapedsteel:（Δ)

b

Δ

Δ

Δ=b/80

5

TheslopingofsideedgeofI&Hshapedsteel:(Δ）b

H

Δ

b

Δ

Δ=b/100

I.3.Processingparts,hollowofpartandpartassembly。

—Singlehollowsofsimilarpartscanbejiggedmanyplatefordrillingatthesametime，Usingafixedofclambingsettoavoidbacklashwhendrilling。Drillholesconnectingpartsbymultiboltsmustbeexactlymarkedandimplementedbypair，dependingonthedrillhole’sdiametertomakeadrillingtestfirst。

-Thedrillholesthatcannotbeconfirmendtobeimplementedfirstshouldbedoneafterstructurecompletiontoensuretheaccuracy。

-Lightstructuralparts:roofpurlin,framepurlintobedrilledbyverticaldrillpressshownonthedetailedmanufacturingdrawingforeachtype。Quantityoftypesandsymmetricbars（ifany)needtobepaidattentionwhenstitching。

—Angle—steelbracewhichhasdrillholeatthetwoendofthebartoconnecttemporaryDhole=db1+2mm

Tolerancetableofprocessingforhighintensivebolt’shole.

No。

Name

Nominaldiameterandallowancetolerance(mm)

1

Bolt

Nominaldiameter

12

16

20

22

24

27

30

Allowancetolerance

±0，43

±0,52

±0，84

2

Bolt’shole

diameter

13，5

17,5

22

24

26

30

33

Allowancetolerance

+1

—0

3

Verticalstraightness

Nomorethan0，03tand〉2,0mm

Allowancetolerancetableofhole’sdistance

No.

Category

Allowancetolerance

≤500

〉500~1200

〉1200~3000

≥3000

1

2

3

Betweentwocontiguousholesofsamegroup.

Betweentworandomholesofsamegroup

Betweenthefirsttwoholesoftwocontiguousgroups。

±0，7

±1,0

±1,2

±1,2

±1。5

±2,0

±3

Afterdrilling,thesharpeninganglesofholesmustbegrindedandcleaned.

II。jiggingcombinationsandCOMPLETELYWELDINGfortheHshapedSTEEL,BRACINGCOLUMNANDSTEELtrusS.

Generalrequirement：inspectionforbilletbeforejiggingsteelstructurecombinations。Allwrongsize，warpingbilletsmustberejectedbeforejiggingsteelstructurecombinations。

II.1.Jiggingandweldingsteeltrussandlinkingbracingcolumntocreateframes:

Erectingmold：moldiserectedonflatfloortoensuregradedimension(ifany）。Thelockcodemustnotbecrossed;thecentrallineofflatisonhorizontal（theweb）shouldbeonthesamelevel（testbybled）

Theworkofjiggingarecarriedoutbymeansoftemporaryattachmentweldthencheckallthegeometricdimensionsoftheframeofsteeltruss,thewarpingofdetailparts,flatsurfacesinsideandoutsidetheframeofsteeltruss。Oncetheparameterscontrolledbytherequirementtoconductcompleteattachmentlinkthenodesofthesteeltruss

II.2.Completelyjiggingcolumnpartsandsteeltruss：

Beforecompletelyjiggingparts:technicaldepartmenttocheckallthedetailswhichweretemporaryfixturesandtorejectallpartsthatdonotmeettherequirementofsize，straightnessandreplacenewones.Partsareonlyjiggedwhentheyareconfirmedforsmoothnessandstraightness.

Whenweldinglinkingbuttonsofthetrussandlinkingbracingcolumnstoconductaccuratelytechnicalrequirementsinordertoavoidimproperweldingprocessescausingwarpingofthelinkcodeduetoshrinkageoftheheat.

Jigginggussetplateofcolumnbase:Beforejiggingcolumn,beammustbestraightened,withoutwarping,theflangemustbeflatsothatthegussetplatewillbecrossedwiththeflangeandthewebtoensuresizeformatching.

Jigginggussetplateofbeamhead:Donelikejiggingcolumns,weldingcombinationshouldbefinishedbeforejiggingparts;bracingstrutsand“conbo”（steelplateunderparlin,ifany)shouldbestraightened，smoothedandnottwisted.

Toleranceofcombinationjiggingbasesontable8:

Table8:

Nameofvariation

Allowancetolerance（mm）

Appliedstandard

1.Flangewarping(foroneside)onlyaftercompletion。

0.005B

(B:Flangewidth）

20TCN170—89

2。Flangefan—in(foroneside）onlyaftercompletion。

0。005B

(B：:Flangewidth)

3.Non-perpendicularbetweenendgussetplatewithwebafterfinishingwelding。

H/100(H:Icombinationheight）lessthan2

FW—SP–0017

4.Crowningofpartaftercompletion。

L/1000nomorethan10mm（applytotruss）

L/1000nomorethan5（applytocolumnandcranebridge)withlengthofpart：L

FW—SP–0017

5.Distortionofpartaftercompletion

0.001Lnomorethan10

20TCN170-89

6。web'spartialwarping

0.003H(H:web'swidthatthemeasuringpoint）

7。Smoothlessonhighintensionbolt-installingsurface(columnend’sgussetplate,crancebeam,trussbase）

<0。3

1.Toleranceofpart’slengthafterfinishing.

3

FW—SP–0017

II。3.WeldingforI，steelbeamstructure，Hcolumnandtruss

1。Weldingmaterials：

-Manualweldingrod:UseE43weldingrodorweldingrodwiththesameintension(FSJ421).

—Automaticalweldingwireandcompound:useH08EorH08AweldingwireandcompoundwiththesameintensionFS—HW08A，HF-402

GettingcertificateformbyVietnamRegistrationDepartment.

2.Weldingprocess：

2.1Manualweldingjoint:

Manualweldingisonlyapppliestoweldpart，nottocombinationwelding(exceptforsmallpartsthatconnotbedonebyautomaticmachine)。Beforewelding，mustdefinepositionforpartsandpayattentiontodeformationinweldingprocess,especiallywithpartsthathavesurfaceinstalledhighintensionbolts。Usingareconductingplatetoensuresimilarmechanicalcapacityatthefirst,endandmiddlepointofweldingpoints.

Ensuringespeciallywelldoneforbuttweldsduringweldingprocess(connectingplangeandweb)adjustelectricpressureasregulationsfromtheweldingmaterialmanufacturer(notedonpackages)toavoiderrorsofweldingjointwhichcausesbyunstableelectricpressure。Manualweldingrodsshouldbedriedbeforeusing.Writtingnameofwelderforweldingjointspositionwhichhehasdone。Allbuttweldingmusthavearcconductingplate.Beforeweldingjoints,weldersmustcleanallpositionofweldingpointandknowweldingpoint’sheight。Usingmoldtocheckofheightofweldingjoints,Ultrawsonicinspectionshouldbeappliedtoallbuttweldsandre-weldallthepointsthatdonotmeetthetechnicalrequirements.

2.2.WeldingsteelstructurewithportweldingmachinemadeinChina.

AfterjiggingforIshapedbeam,Hshapedcolumnandtruss,usingcranebridgeinworkshoptoliftcombinationstoautomaticweldingmachine。

Thejiggingbeamiskeptslopingonthefixedbracket,(unmovable)。Themachinehastwosupportedbracketssothatitcanweldtwobeamsatthesametime。Afterbeinginstalledandadjusted，towedingheadsautomaticallyprotrudetothepositionneedtobeweded.Theframeismoving，thebitsasoperatingandbeamisweldedonallitslength.

-Weldingproess:Adjustweldingangleofbittoavoiddefectedfootwelding,adjustingweldingcurrentandvelocitytoavoidburningrootofweldingjoint;toensurejointsareevensmooth,lustrousandhighenoughasdesign。Usingarcsheettoensurequatilyofweldingjointatthefirstandendpointsaresimilarasthemiddleone。Weldermusthavemoldtoeasureheightofweldingjoint.Writtingwelder'snameinthepositionofeverypointhemade。

WecommitthattheuseofautomaticportweldingmachinetoproducesteelstructurewillguaranteetheprogressandthequalityofproductsthattheInvestorswant。

Table9：

ApplytoAWSplates

Msterialsuseforautomaticandmannualwelding

Appiedstandard

Manualweldingrod。

FS-E421

E43

ConversionperarticleA5.1—91ofAWS

Weldingrod'sdiameter

4

4

Autoweldingwire

FH—HW08A

H08A

Autoweldingcompound

HF—402

EL12

3.Checkingweldingjoint。

3。1Buttwelding：

—Byvisual 100％

—Byultrasonic 100％forsteelwiththickness≥8mmappliedasVietnamstandard6735:2000（BS3923—1：1988）

-Checkingbytest（tensiletest)forsteelwithvariuosthichnesses:01sample/pertest。

3。2。angleweldjoint:

-Byvisual： 100％

—BymoldasVietnamStandard338-2005： 100％

-Byultrsonic: 0％

Defectsattheweldingjointfoundduringcheckingwillberecorded.Allnecessaryworksforrepairingdefectsanderrorswillbealsorecordedaswell.Theweldingjointmustbecleandtoensurenon-residuaryofdefectsduringchecking。

DefectingtolenceofanglejointweldasinfigureAandBareaccepted.DefectsasinfigureCmustberepaired。

DefectingtolenceofbuttweldasinfigureDisaccepted，defectsasinfigureEmustberepaired.（AccordingtoAWSD1.1page40)

PictureA:Bestweldingjoints

PictureB:AcceptabledefectedweldingjointwithCpointisfrom0。1Sto0。8mm

(S：lengthmeasuredaccordingtotherightanglesideoftheweldingjoint）

PictureC:unacceptabledefectedweldingjoints

PictureD:AcceptablebuttweldingjointwithR=0to3mm。

ErrorweldingjointInsufficientweldingjoint（notfullydone)Burned-baseweldingjointbearingweldingjoint

3.3.StraighteningIshapedbeam,Hshapedcolumn，andtrussafterwelding：

Afterwelding,Ishapedbeam，Hshapedcolumnandtrussalmostarewarpedanddeformedbecauseofheat.Therefore，wehavetostraightenthemagainasinitialdesign。

StraighteningIshapedbeamwillbeprocessedbystraighteningmachine.Procedureofstraighteningforbeamstraighteningisasfollows：usingcranebridgeintheworkshoptolifttheIshapedbeamorHshapedbeamuptobedofstraighteningmachine.PressingelectricbuttonforoperatingreelsothebeamwillmoveonalongitsbedsmoothlywithoutanyproblemsfortraslationalmovementofIbeamorHbeam.AdjustingthestraighteningengineofmachinegraduatlylowerdowntotheundersidesurfaceofIbeamorHbeam.Bushinggreaseonsurfaceofbeamrib。Pressingstartbottonforhydraulicengineofstraighteningbeamtooperatetogetherwiththereelsothatthebeamsurfaceisalwayscontactedwithbeamstraighteningengine,pressureforcewillbeincreased。IshapedbeamorHshapedbeamismovingtranslationallyonenginefewtime，itwillbestraight,smoothlyasdesign。

ProcedureofstraighteningsteeltrussisdonebymanualstraighteningtechniquewithGas-oxygenburnerisasfollows：professionalworkerswithknowledgeandexperiencewillobservewiththenakedeyeandsupportingdevicestodeterminethepositionstoimpactheatingandcoolingimmediatelytoputthesecomponentsarelinkedintothesystembacktoflatlayoutwhichisallowedasthedesignandcurrentregulations。

Checkingweldjoint:

Buttweld

Byvisual100％

Byultrasonic:

Steelwiththickness≥8mm：100%(asVietNamstandard6735：2000).

Steelwiththickness<8mm：0％(asVietNamstandard6735:2000).

Angleweldjoint

Byvisual100％

Bymold（asVNstandard338-2005)100%

Byultrasonic0％

3。4.weldingsmallparts，finishingweldforbeam.

AfterstraighteningHbeamrid,thecranebridgewillliftthebeamontothewagonandmovetothecompleteweldingstage.Righthere,thebeamisweldedadditionalheadplate,bracingstrut,supportedbeambug，gussetplateforbrace，etc…togetherwithdrillinganddrifting…

Beforewelding,thesurfaceofelementsmustbecleanedattheweldingpointswithnolessthan20mmofwidth.Assembliesmustbecheckedbeforewelding.Nextlayersareonlyallowedtoweldwhenstains，dirty，craksofpreveouslayerwithcavityarecleaned。Thesizeofeachweldingjointmustbefollowedasspecifiedstructuraldrawing.

Weequippedmodernmachinessuchas：6—burnerweldingmachine,CO2gaswelding,drillersandpunching—and—shearingmachineintheworshop。

Thesefollowingtolerancesmustbeensuredtoexe