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AMERICAN TECHNICAL PUBLISHE RS, INC.HOMEWOOD, ILLINO IS 604304600

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Welding Skills. 3'" Ed ition and CD-ROM contain welding procedures commonly practiced in industry. Specificprocedures vary from plant to plant and must be performed by a qualifi ed person. For max imum safety. always referto spec ific manufacturer recommendations; insurance regulation s; specific plant procedures; applica ble federal,state, and local regul ations; and any authority having ju risdicti on .

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The author and publisher are grateful fo r the technical in formation and assistance prov ided by the[allowing companies, organizations, and individuals:

L

AircoAmerican Welding Soc ietyASI Robi conBach arach, Inc.Baker Testi ngBernard Weld ing Equipment Co mpanyBobcat Company, a Unit of Ingersoll-RandBoeing Commercial Airplane GroupBuehler Ltd .Chrysler CorporationCleave r-Brook sCo lumbus McKinnon Corporation, Indu stria l

Products DivisionThe Duriron Co, Inc.E.!. du Pont de Nemours and CompanyESAB Welding and Cutting Produ ctsExxon Co mp anyFanuc Robot ics North Amer icaFaxitron X-Ra y Corp orationG.A.L. Gage CompanyHarrington Hoists, Inc.Haynes International, Inc .Hobart Welder sIronworkers, Local Unio n 378

Thoma s J. ClarkIronworkers, Local Union 378

Charlie R. CramletE.!. du Pont de Ne mours and Co mpany

Dave DonerPrairie State College

Dave He idemannMiller Electric Manufact uring Company

Kamw eld TechnologiesLECO Co rporationThe Lincoln Elect ric Co mpa nyLOCK-N-STITCH , Inc.LPS Laboratories, Inc.Miller Electric Manufacturin g CompanyMo tornun, Inc.Nederman , Inc .Osborn Internationa lPandjiris, Inc.Rath ManufacturingSciaky, Inc .Sell strom Manufacturing Co.SIFCO Selective Plating, Cleveland , OHSmith EquipmentSPM Instrument, Inc.Stork Technimet, Inc.Thermady ne Industries, Inc .Thermo GasTechTiniu s Olsen Testing Machine Co., Inc .Victor, a Division of Thermadyne Indu str ies, Inc .Wall Colmonoy Co rporationWeld Tooling Co rp.

Thomas P. HeralyMilwaukee Tec hnica l Co llege

Ga ry ReedSIFCO Selective Plating

Glen SchulteJoli et Junior Co llege

Mark SchumannMill er Electric Manufacturing Company

nt nts

sec tion . 0 n e

lNhere WeldingisUsed . Developmentaf WeldingProcesses Wek:1.ing Processes OccuPOtionoiOpportunities on Welding

1 An Essential Skill --::--:-:--:---::-_----: lPoints to Remember 7

Questions for Study and Discussion __ 7

2 Welding Safety ---------------::--c--:-,.---::-----:---~9JobSReSotety .SofeEqlip'nent()pe

section. t h r e e

8 SMAW-Equipment 89ElectricalPrinciples .. Welding Machine Output .. Constant-Current Points to Remember 103WeldingMachines..StaticPowerSources ..Engine-Driven PowerSources - Welding Machine Ratings. Welding Equipment . Shop Questions for Study and Discussion _ 103Equipment ..Personal Protec tive Equipment

105Points to Remember 115

Questions for Study and Discussion _ 116

SMAW-Selecting Electrodes _Elecfrcx1es .. IdentifyingElectrcx1es ..Selecting CorrectElectrodes ..Cor1seMngandStoring EIec"odes . Electrode Classification .IoOriobIesof5electrlgEIec"odes SpecioIEIec"odes

9

117Pointsto Remember 120

Exercises 121Questions for Study and Discussion _122

10sMAw-Striking an Arc _BasicPrinciplesofSustainingaWeldingArc .. CheCkingandAdjustingEquipmen' , GrippingtheEIec"ooe . Adjusting theCurrent

11SMAW-Oepositing a Continuous Bead

Essentiols of Arc Welding .. Electrode Selection .. Arc Length ..C urrent Selection .. TravelSpeed .. Electrode Angle " Cra terFormation .. ControllingCra ters ..Arc Blow


Exercises 130Questions for Study and Discussion _ 131

12sMAw-Flat Position _

Weld ccsses .. RootA::::l:ss ..rveareoaie Weld Pass..CoverPoss ...k:Ji1tsWeldedhRatPosition..LcpJoinfs .. T-Joints ..ButtJoi1ts ..ComerJoi1ts ..9.rfoc:tlg ..S\ofAWRatPosition Problems



13sMAw-Horizonta, Position _

Horizontal Position Welding . WeldingProcedure . DepositingBeads in Horizonta lPosition. Weldinga Single-Pass LapJoint inHorizontalPosition . Welding a Multiple-PassT-Joint inHorizontaiPosition



14SMAW-Vertical Position _

DownhO Welding . UphiI Welding . Uphill Welding _ 0 IfVhi:>pingMotion Uphill Welding with a Weaving Motion . -7018ElectrodeWelding rechnique





15sMAw-overhead Position _Ove

fo u rst nA(c W tdlf\9 (

23 Brazing, Braze Welding, & SolderingBrazing . Manual Brazing . Production Brazing . Braze Welding . CastIron Braze Welding . Broze Welding Disadvantages . Soldering .Heating Devices. Soldering Techniques . Insp ecting SolderedJoints


Questions for Study and Discussion _264

24 Surfacing _Surfacing . Wear Types Surfacing Methods . Welding . GTAWanaGMAWOverlays . PAW WeldOverlays . SAWWeld Overlays .Surface Preparation . Weld Overlay FillerMetals . Thermal Spraying



25 Cutting Operations _CuttingOperations . Oxyfuel Cutting Gases Tarches. Piercing Holes .Beveling . Cutting Round Stock. Cutting Cast Iron. PIosmaArcCutting(PAC) . AirCarbonArc CUffing(CAC-A) . SofetyPrecoutions

283Points to Remembe r 294


26 Repair Welding _Evaluating RepairMethods. Mechanical RepairMe thods. WeldRepair Methods . Weld RepairPlans



27 Pipe Welding _Pipe Classification . Pipe Connections . Pipe Joint Preparation .Welding Passes . Pipe Welding Techniques . Pipe Welding Standards Welding Methods . Pipe Weld Testing



28 Production WeldingResistance Welding . Stud Welding . Electron Beam Welding 'Friction Welding . Laser Beam Welding . Plasma Arc Welding.SubmergedArc Welding . Electrogas Weld ing. Adhesive Bonding



29 Automation & Robotic Welding _Automation InProduction Welding . Automatic Welding Equipment .WorkArea andSafety



30 Plastic Welding _TypesofPlastics . Hot Gas Welding. Heated-Tool Welding .Induction Welding . Friction Welding




Questions for Study ond Discussion _ 41 2

31 Destructive Testing _Destructive TestTypes Tensile Test. Shear Test Bend TestHardness Test ToughnessTem Break Tests . Specimen Preparation ResidualStress Management

______________ _ 4 13Points to Remember 447

Quest ions for Study and Discussion _ 448

3 2 Nondestructive ExaminationVwdExamination (VT) . Uq.jdPene"crot Examination (PT) . Mog>effcPa1ideExc:rrW1ation(MT) el.Jltrosor'; Exa ,1Ii lO1iOn(lfT) . RodogophicExcrrW'lation (I?T). ElectrOfTXJg1eOC Exa 'Ii IOtiot I (EJ) ProofTesti'>g

33 Metallography 449Mcro9x>(:>cExaminalion .Cut1hgCTldr.buglGii1g .MofngCTld Points to Remember 463FheGii1g . r.bugl CTldFhdPoislWlg. EtchhgCTldExamina1ion .MoaoscopicExamina1ion .MacroetchhgCTldExamina1ion .Lig1fng Questions for Study and Discussion _ 464

Weld Stresses . Crocks . Cavities Inclusions Incomplete Fusion andIncomplete Penetration . Incorrect Shape MiscellaneousDiscontinuities

34weld Discontinuities 465Points to Remember 484

Questions for Study and Discu ssion _ 484

35Weld ing Procedure Qualification 485Welding Procedure Qualification vcutao tes Weld ing Proced ure Points to Remember f()1Specification (WP$) Proc edure Qualification Rec ord (PQR)


503Pointsto Rem ember ffF


36Welder Performance Qualification _WPQ standardsandCoces e PrOduct-Specific WPQs



37Weld ing Metallurgy _MetoJlurgicolStnJcture . WeidRegions . EffectofWeldingonPhysicoJProperties EffectofWelding on Mechanical Properties Effect ofWe/ding stresson Welds EffectofWelding on Corrosion_croce

38Meta l Identification _Manufacturer Paperwork MaterialsNonconformance Report .V/SUOf ldenfffication Qualitative Identification . Semi-Quontitativeldenfffication Quantitative ldentdication





39Weldability of Carbon & Alloy Steels _Carbon o ndANoySteels Steel Deoxidation . General WeldingConsiderations for Carbon andAlloy SteelS . scecec WeldingConsiderations (Of Carbon andAHoySteels



40Weldability of Tool Steels & Cast Irons _Weldabilityof Too lSteels . General Welding Considerationsfor Too lStee/s We/dabilityof Cast irons . General Welding ConsiderationsforCastlrons

581Pointsto Remem ber 595

Questions for Study an d Discussion _595

41 Weldability of Stainless Steels _We/debility ofSfainless steels. General Welding Considerations forstainless Steels . Specific Welding Considerations for stainlessSteels



42Weldability of Nonferrous Metals _We/debility ofNickel Alloys . We/debility of Copper Alloys Weldabllify ofAluminum Alloys. We/debility ofMagnesium Alloys.We/debility of Titanium Alloys

4 3 Distortion ControlDistortion . Weld Metal Shrinkage . Bose Metal Shrinkage . DistortionCootto; Mechanlcol Restraint Methods . HeatShaping. DistortionControl otComponents ResidualStress





44welding Symbols _Welding Symbols. Combining Welding Symbols . NondestructiveExamination Symbols

45 Materials & Fabrication Standards & Codes _Moterials standards . Materials Standards Organiza tions. UsingMaterials Standards. Fabrications standards andCodes

639Points to Remember 6(fJ

Questions for Study and Discussion _ 6(fJ

Appendix _Glossary _

Index

661

687709

CD..ROM Contents Using This CD-ROM Quick Quizzes' Illustrated Glossary Welding Resources Media Clips Reference Material

I~"'''''' u e

Weldin g Skills, 3'" Edition, is the product of an extensive revision effort to addres s all aspects of thewelding trade and the latest we lding techno logy. Now in full co lor, th is co mpre he nsive text has beenco mp letely updated and expanded to co ntinue the tra dition of an indu stry- leading instructional tool. Anew contemporary de sign, detailed ill ustrations, descriptive photographs, and concise te xt enhance thelearning prucess. Step-by -s tep exercises, c urrent AWS terminology, key po ints, and in fonnut ive fac toidssupplement esse ntial content throughout the text.

The Th ird Edition builds on the quality of previous editions and offers valu abl e new content contributedby Bert J. Moni z. Having over 37 years of experie nce in met all urgy and many facet s of we lding , Mr.Mo niz current ly serves as Materials Engineering Co nsu ltant with the DuPont Company. In his cu rrentpo sition, he is involved with selecting materials for construction, fabr ication , and fai lure analysis world-wide . He has taught re lated co urses, authored book s, and written and presented several papers. His hands-on knowledge and experti se are reflected throughout the text and in the development of new chapterscoveri ng:

Repair WeldingMe ta llogra phyWeld Disconti nuitiesMetal Ide nt ifica tionWeldab ility of Common Meta lsDistort ion ControlMa terials and Fab rication Standards and Codes

The text beg ins with an int roduct ion to the welding process and we lding in industry. Throughout the textan emphas is is placed on fundame nta l pr inciples of welding processes, equipment , welder performancequalificat ion, and we ld evaluat ion and testing. T he text also covers the latest technol ogy in we ld ingmetallurgy, metal weldability, distortion co ntro l, robotics , and material standards and codes. Chapters inthe text ha ve been organized into eight sections to progressively enhance knowledge and skills . Safetyprocedu res and potentia l health and safety hazard s are covered in co ntext with appropriate cautions andwarnings. The Appendix contains reference material pertinent to the we lding trade , and the Glossaryprovides definitions of we lding terms introduced in the text.

The Weldin g Skills , 3'" Edition CD-ROM in the bac k of the book is a self-s tudy aid designed to aug mentco ntent included in the text. The CD-ROM include s a Quick Quiz" for each section of the text, anIl lustrated Glo ssary , Medi a Clips, Weld ing Resources, and re lated we lding re ference material. Informa-tion about using the CD-ROM is incl uded on the last page of the book.

Welding Skills, 3'" Edition, is one of several high-qu alit y training products ava ilab le from American Tech-nical Publishers, Inc . To obtain inform ation about related training products, visit the Ameri can Tech website at www.gozatp.com,

The Publi sher

section. 0 n e Introduction to Welding

Weldillg is WI efficient , dependable, fl exible. ami economical mealls of fabrication. Weldillg is widelyused ill industryas a principal means offa bricating and repairing metal products. Weldillg call lowerproduction costs by simplifying design and eliminating costly patterns and machining operations. Weld-illg call also be used in repair operations and adding new metal to worn parts.There are many opportunities for welders trained in welding techniques, materials. designs, andapplications.

WHERE WELDING IS USEDWelding is the coalescence or joiningtogether of metals, with or without atiller meta l, using heat, and/or pressure.Bonding of metals dur ing welding oc-curs through localized me lting or mi-crostructural changes at the interfacebetween the metal s. Weldi ng is usedthrou ghout industry in building co n-struction, aircraft manufacturing, and forautomobile producti on. See Figure 1- I.

Welding is used extensively for themanufacture and repair of farm equip-ment , mining and refin ery equipment,

and jigs and fixtures; and in the con -struction of boi lers . furnaces, and rail-way cars . Welding is also common tyused in the manufacture of product sfor ho usehold use, such as te levisionsets, refrigerators. storage cab inets, anddishwashers . Construc tion of bridgesand sh ips a lso commonly require swelding.

o Nearly two-thirds ofall welders work in thecons truction. transportat ion eq uipment.fabricated metal products. machinery. andmotor vehicle and equipment industries.

8",,;/1/1 l

I"= IThe combustion of l/.~ mixture of acetylene. = and oxygen produces

(J fl ame that is suit-able fo r welding andcutting.

tI The primary du ty of{/.~ welder using oxyj uel.= welding is to contro land direct heal 0 1110the edges of the metal10 be joined.

2 ' Welding Skills

DEVELOPMENT OF WELDINGPROCESSESModern welding processes evolvedfrom discoveries and inventions dat-ing back to the year 2000 B.C . whe nforge we lding was first used as a meansof joining two pieces of metal. It was acrude process of joining metal by heat-ing and ha mme ring until the objectswe re fu sed together. Toda y, forgewe lding is used only in limited appl i-cations.

Acety le ne gas was discove red in1836 by Edmund Da vy. When com-bined with oxygen, acetylene produceda flame suitable for we ld ing and cu t-ting . The application of heat generatedfro m an e lectric arc be tween carbo nelec trodes was the bas is fo r the arcwelding process. Resistance we lding,whic h also uses electric ity, was al sodevel oped in the late 1800s and fir stused in the early 1900s.

One of the most significant de vel-opments at the time was the inventi onof an elec tro de that is co nsumed intothe weld while providing heat from anarc ( the sh ie lded metal arc we ld ingpro cess). Modifications to the coatingapp lied on the consumable e lec trodeallowed greater appl ications fo r arcwelding.

A nothe r improvement in the a rcwe ld ing proce ss was the add itio n ofan ine rt shield ing gas to protec t thewe ld area fro m atmospheric contami-nation (the ga s tun gsten arc we ldi ngprocess). T his proved to be an espe-cia lly im portant pro ce ss in weldi ngmagne sium and al umi num on WorldWar II f ig hter pla nes . The el ec trodeused was made out of tungsten and wasno t co nsumed into the weld . Origi -nall y, helium was used as a shieldinggas, but was later replaced by the lessexpe ns ive argon .

Ne w devel opments in the fieldcontinue to add ress new requi rement sand applications in industry. C urrentwe ldi ng processes are the product of

continued refinemen ts and va riationsof the we ld ing processes d iscov eredin the 1800s.

WELDING PROCESSESThe demands of a growing industrialeconomy during the 1800s spurred thedevelopment of modern we ld ing pro-cesses. The welding process to be usedfor a particular job is de termined bythe foll owin g: type of metals to be joined costs invol ved nature of products to be fabricated production techniques used job locati on ma teria l appearance equipme nt availab ility welde r ex perience

Welding processes used today are com-monly classified as oxyfuel welding, arcwelding, and resistance welding. See Fig-ure 1-2.

o In 18 / 0. Sir Humphrey Davy discoveredthat an electric o re could be maintained atwill bybringing two terminals a/high volt-age electricity near eac h othe r: The lengthand intensity could he varied by adjustingthe voltage ofthe circuit.

Oxyfuel WeldingOxyfuel welding (OFW) is a group ofwe ld ing processes that use heat fro mthe co mb us tion of a mi xture of oxy-gen and a fuel for welding. Ace tylene ,me thy lacetylene- pro padiene stabi lized(MA PP) gas, propan e , natu ra l gas,hydrogen, or propylene may be used .The heat is obtained from the combus-tion of a combustible gas and oxygen.OFW welding processes are used withor without filler metal. If filler metal isnot used in the join t, the weld is au -togen ous . An autogenous weld is afusion weld made without filler metal.

Oxyace ty lene we ld ing is the mostco mm onl y used oxyfue l process.Oxyacety lene welding (OAW) is a noxyfue l we ldi ng pro cess that use sacetylene as the fuel gas.

OXYFUEL WELDING (OFW)

I, SMAW electrodes can.~ be modified to allow.= jor wider applicationof SMAW processes.

Arc welding (AW) is a group of weldingprocesses that produce coalescence ofmetals by heating them with an electricarc. The arc is struck between a weld-ing electrode and the base metal. Thewelding electrode is a component ofthe welding circuit that terminates atthe arc. The joint area is shielded fromthe atmosphere until it is cool enoughto prevent the absorption of harmful im-purities from the atmosphere.

AW is the most common method ofwelding metals. AW processes includeshielded metal arc we lding (SMAWi,gas tungsten arc welding (GTAW), gasmetal arc welding (GMAW), flux coredarc welding (FCAWi, submerged arcwelding (SAW), and plasma arc weld-ing (PAW).Shielded Metal Arc Welding. Shieldedmetal arc welding (SMAW) is an arcwelding process in which the arc isshielded by the decomposition of theelectrode coating. The electrode is con-sumed into the weld while providingheat from an electric arc. Variations incomposition of the electrode coatingallow different applications of theSMAW process.

Common applications of SMAWare in the fabrication of machinery andstructural steel for buildings andbridges. SMAW is considered ideal formaking storage and pressure vesselsas well as for production-line productsusing standard commercial metals.SMAW is also used in repair work andin welding large structures.

Gas Thngsten Arc Welding. Gas tung-sten arc welding (GTAW) is an arc weldingprocess in which a shielding gas protectsthe arc between a nonconsumable (does

Arc Welding

Because of its flexibility and mo-bility, oxyacetylene welding is used inall metalworking industries, but is mostcommonly used for maintenance andrepair work.

-

-

ELECTRODEHOLDER

ELECTRODES

[

HEAT FOR WELDINGPRODUCED BYCOMBUSTIONOF OXYGEN AND FUEL

[

WELDINGTORCH

ARC WELDING (AW)

HEAT FOR WELDINGPRODUCED BY RESISTANCE TOFLOW OF ELECTRICITY

RESISTANCE WELDING (RW)

GROUND CLAMP

WELD

HEAT FORWELDING

PRODUCED BYELECTRIC ARC )

WELD

FILLERMETAL

Figure 1-2. Welding pmce.lses are commonly cla ssified asOXyflid welding, arc welding. and resistance welding

An Essential Skill 3

tI FCAW uses a tubu -.~ tar ~/~cfrode with.= flux 111 Itscore.

4 @o Welding Skills

not become part of the weld) tungstenelectrode and the weld area. GTAW usesa nonconsumable tungsten electrode anda shielding gas, usually helium or argon,for welding. The GTAW process can beused to weld using filler metal, or with-out filler metal to form an autogenousweld. GTAW is widely used for joiningthin-wall tubing and depositing the rootpass in pipe joints. GTAW produces avery high-quality weldment.

Gas Metal Arc Welding. Gas metal arcwelding (GMAW) is an arc welding pro-cess that uses an arc between a continu-ous wire electrode and the weld pool.Argon is used as a shielding gas for non-ferrous metals such as alumin um, andcarbon dioxide/carbon dioxide mixtures(such as 75125, 98/2) with argon areused as a shielding gas for steels. TheGMAW process uses a continuously fedconsumable wire, eliminating the needto stop and change electrodes. This hasincreased the popu larity of GMAW inmanufacturing.

Flux Cored Arc Welding. Flux coredarc welding (FCAW) is an arc weldingprocess that uses a tub ular electrodewith flux in its core. FCAW producesfast, clean welds with excellent ap-pearanee and high deposition rates ,and the process can be automated.

Like GMAW, the primary benefi tof FCAW over SMAW is the hig herproductivity rate possible with thecontinuous-feed system, which alsoresults in lower production costs .FCAW is commonly used to weld car-bon, low-alloy and stainless steels, andcast iron. Typical applications includefie ld and shop fabrications .

Submerged Arc Welding. Submergedarc welding (SAW) is an arc welding pro-ces s that uses an arc between a baremetal electrode and the weld pool. Theelectrode, are, and weld pool are sub-merged in a granular flux poured on thebase metal. SAW is limited to flat or low-curvature base metals. SAW produces

high-quality weld metal with fast depo-sition rates. The weld surface is smoothwith no spatter. SAW is automated andmost often used to join thick metals re-quiring deep penetration, such as inheavy steel plate fabrication.

Plasma Arc Welding. Plasma arcwelding (PAW) is an arc welding pro-cess that uses a constricted arc betweena nonconsumable tungsten electrodeand the weld pool (transferred arc), orbetween the electrode and constrictingnoz zle (non-transferred arc) . Trans-ferred arc PAW produces a deep , nar-row, uniform weld zone and is suitablefor almost any metal.

Transferred arc PAW is used forwelding high-strength, thin metal.Non-transferred arc PAW is typicallyused for thermal spray ing.

Resistance WeldingResistance welding (RW) is a groupof welding processes in which weld -ing occurs from the heat obtained byre sistance to the flow of currentthrough the metals joined . A resistancewe ld ing machi ne fu se s meta ls to-gether by heat and pressure . RW isused to make localized (spot) or con-tinuous (seam) joints. An advantageof resistance welding is its adaptabil-ity to rapid fusion of seams.

RW uses special fixtures and au-tomatic handling equipment for themas s production of automobile bod -ies, electrical equipment, hardware, orother domestic goods. RW can be usedfor joining almost all steels, stainlessstee ls, aluminum alloys , and somedis simi lar metals .

OCCUPATIONAL OPPORTUNITIESIN WELDING

The widespread use of welding inAmerican industry provides a constantsource of employment for welders.According to the U.S. Department ofLabor, there are approximately 588,000

persons employed as welders. Over halfof these work in industries that manu-facture durable goods such as transpor-tation equipment , machinery, andhousehold products. Many others workfor construction firms and repair shops.A growing number of welders are re-quired to operate automated and roboticwelding machines .

Employment OutlookOpportunities for those who desire tobecome welders differ by occupationalspecialty. A healthy economy and aneed to replace experienced workerswho leave the field create a demandfor welders . Certified welders, espe-cially those certified in more than oneprocess, have better employment op-portunities than non-certified welders.

Although many companies haveautomated some tasks traditionally per-formed manually, qualified welders arestill required . Many automated weld-ing machines and robots require asingle operator overseeing multiple op-erations . However, fabrication and re-pair applications are still common inthe welding industry. See Figure 1-3.

TrainingTraining to be a welder is availablefrom different sources. Many schoolsoffer comprehensive welding trainingprograms . Company training programscan vary from a few months of on-the-job training to several years of for-mal training. Apprenticeship programsthat include welder training are alsoavailable through unions such as theInternational Association of Bridge,Structural, Ornamental, and Reinforc-ing Iron Workers or the InternationalUnion of Operating Engineers (IUOE).Most employers prefer applicants whohave some welding experience andcourses in mathematics, mechanicaldrawing, metals, and blueprint reading.

TI1~ Lincoln t.1eoric Com!,lIlI )'Figure 1-3. Robotic wetding machines arc pro -grammed to perform repetitive welds on mass-producedproducts and require supervision bv 11 skilled weld-ing machine operator.

Welders must have good manualdexterity, eyesight, and hand-eye co-ordination . They should be able toconcentrate on detailed work for longperiods and must be free of physicaldisabilities that would prevent them frombending, stooping, or working in awk-ward positions. Welders must also beable to lift 50 Ib regularly and 100 Iboccasionally.

Before being assigned to workwhere the quality and strength of theweld are critical, a welder generally hasto pass a certification test given by anemployer, government agency, or in-spection authority. See Figure 1-4.Typically, welders are certified by anemployer to perform specific welds .Recent efforts by the American Weld-ing Society (AWS) allow certifiedwelders to be listed on a national reg-istry. The national registry assists em-ployers in finding employees that haveattained a particular skill level.

The needforcertifiedwelders continues togrow in the weldingilU/US!!)'.

The American wa:ing Society (AWS)maintains a nationalregistry of certifiedweldersto assistem-ployers in findingemployees that haveattaineda particularskill level.

An Essential Skill ~ 5

Figure I-t Welders are certifiedby WI employer. governmentagency. or inspection authori ty toperform .\{1f'Cijic ~retds.

Job ClassificationsWelding jobs differ in the degree ofskill required. Welding machine opera-tors can learn the required proceduresin several hours, while welders mayneed years of on-the-job training tomaster their craft. A beginning welderusuall y starts on simple productionjobs and gradually works up to higherlevels of skill with experience.

Welders mu st have a workingknowledge of metal propert ies andeffects of heat on welded structures.They mus t also have an understand-ing of how materials are fabricat ed.Welders must be able to read detaileddrawings, prepare the work area, con-trol expansion and contraction forces,

The need for certified welders is growing as experienced welders leave the workforce.

6 @o Welding Skills

read welding symbols, recognize welddefects, and perform all tasks requiredto fini sh the we ld ing job. A weldermay be proficient in several weldingtask areas or a specific weld ing task.As a rule, the welder is always certifiedfor the specific welding task required .Skilled welders may, by promotion ,become inspectors or superv iso rs .Some of the principal job titles of weld-ers include the following:

Welder Helper. Entry-level welder,clean s slag for Welder, positionswork pieces, helps move material s.

Welder. Person who performswe lding using the required process.

Welder Operator. Welder who op-erates automatic welding equipment,such as that found on automobile as-sembly lines.

Pipe Welder. Welder with additionaltraining and certification in welding pipe.

Welding Layout lind Set-up Person .Welder with printreading experience.Must prepare workpieces for welding .

Some welding personnel are re-quired to oversee welder certification,instruction , and quality con trol. Thefollowing supervisory positions requireadditional training:

Welding Inspector. Certifi ed welderwho has undergone additional certi -fication to work as an inspector.

Welding Supervisor. Per son withgood management skills who can ef-fectively run a weld shop and maintainthe requ ired we ldi ng sc he dule andqualit y of workmanship. Welding su-pervisors must be knowledgeable aboutcompany standards and procedures.

Welding Instructor. Person employedby a high school, community college,vocationa l prog ram, or appre nticeshipprogram. Instructors must be certifiedto meet AWS standards.

Welding Engineer. Person with aco llege degree and professional certi-fication qualified to specify necessaryweld requirement s.

I . The combus tion of a mixture of ace tylene and oxygen produces a flame that is suitable forwelding and cutting.

2. The primary duty of a welder using oxyfuel welding is to control and direct heat onto the edgesof the metal to be jo ined.

3 . SMAW electrodes can be modified to allow for wider application of SMAW processes.4 . FCAW uses a tubular electrode with flux in its core .5. The need for certified welders continues to grow in the welding industry.6. The American Welding Society (AWS) main tains a national registry of cer tified welders to

assist emp loyers in find ing employees that have attained a particular skill Icvel.

I . Name some manufacturing appli cations for which weld ing is commonly used.2. What is the basis of the arc welding process?3. Name the three common classifications of welding processes used today.4 . Define autogenous weld .5. What is the most common welding method used for welding metals?6 . What is one difference between FCAW and GMAW?7. What is transferred PAW typically used for? Non-transferred PAW?8. List training programs that provide education for welders.9. What are some skills that all welders should have?

An Essential Skill @o 7

8 ~ We/dillK Skills

Every year, thousands of welders suffer injuries as a result ofaccidents that occur because proper safetyprecautions are notfollowed at the joh site. Accidents occur because of indifference to regulations, lack (II'information, or carelessness. Any injury can he painful and can incapacitate a person, or lead to permanentdisability or death.

Safety precautions are effective in reducing the occurrence ofaccidents at the job site. Safety means usingcommon sense and avo iding serious accidents; and it has to be observed constantly. Established safe typractices should be fo llowed at all times. If good safety pra ctices are consistently fo llowed, an awarenessofproper beha vior is established that usually prevents mistakes.

JOB SITE SAFETYIndustry places a strong emphasis onsafety in the workpl ace. A tremendousamount of time and effor t is spent onsafety training and awareness. The Oc-cupational Safety and Health Admini s-tra tion (OSHA) sta nda rdizes sa fe typractice s for most types of work envi-ronments. The Occupational Safety andHealth Administration (OSHA) is a fed-eral agency that requires all employersto provide a safe environment for theiremployees. See Figure 2-1.

Employers are responsible for safetytraining at the job site and for ensuringthat their employees are familiar with,and follow, OSHA reg ulations. Mostcompanies have a comprehensive new-hire training program to cover the over-all safety requirements of the company.Weekly safety meetings and/or toolbo xtalks are also held to di scuss currentsafety topics and employee safety con-ce rns, and to an swer any employeequestions. Attendance at these meetings

is usually required and is beneficial forkeeping current with company safetyregulations. Safety meetings are a goodway for employees to keep curre ntabout potential hazards that have arisenor to inform a supervisor about hazardsthey have noticed at the job site.

9

Weekly !illfety meet-ings are a convenientway for employersto discuss relevantjob site safety issuesami concerns .

Figure 2-1. The OccupationalSafetv and Health Administration(OS I/A) requ ires enwlovers IIIprovide (J safe work environmentfo r emntovees.

Reporting AccidentsAccording to the Bureau of Labor Statis-tics, approximately 26,000 welders per yearare injured on the job site. Welders are ex-posed to health risks every day: the ultra-violet rays of the welding arc can injurethe eyes or the skin; some gases producedby welding may be toxic and if breathedin may affect the lungs; and welding orcutt ing near t1ammable material s, orwelding on conta iners that hav e heldcombustible materials, poses a fire risk.

Whi le precautions must be take n toprevent injuries, accidents do happen. Allaccidents should be reported, regardless

of how minor they may be. A small scratchmight lead to a serious infection, or a minuteparticle lodged in the eye could result in aserious eye injury. Prompt attention to anyinjury usually minimizes the seriousnessof the injury. See Figure 2-2.

Any job site where physical work isperformed should have an established ac-cident reporting procedure, Since this re-porting procedure is in the best interest ofthe worker, it is irresponsible to ignore it ortry to avoid reporting an accident. Instead,workers should become fully informedabout what should be done and then takeimmediate action if an accident occurs.

CIRCUMSTANCES

CAUSE OFACCIDENT

Accidool Classification~ Firsl Aid OrlyD Medical Trealment

D Month

ACC IDENT REPORT OF INJURY

10. Enter Employee Rale01 Pay (No o"a'l ima) $ ," '

EmP!oyeeSlatusI Fu'lTimao Parl Tima

INJURED 0 Othe,__PERSON~ -

I ~NFORMATION1. Name aTEmplO)'ee Sandra Rugan Social 8ecuntv. OQO-lf. 336 + TIM E OF2. Addr&SS Z l Eucl jd West Ridge WI HomePhooo. 5 55-0010 I ACCIDENT

DATE OF 3 Age 29 Sex F Occupati"""'~le fACCIDENT 4 Was Employee engaged ,n '611uiar course ot hie duties at lome of aCCidem II' Yes 0 No

----+-------- , "......... ~ ~PLACE OFI ~ork~a~lv ty __2__ Y9a,... _ months w~ I ACCIDENT7 Dale 01A

Work Behavior

Occasionally, workers may engage inwhat might appear to be harmlesspranks . However, there are many re-corded incidents where a prank endedin serious injury. Any form of horseplayin a shop is dangerous and can lead toan accident. Most work areas are rea-sonably safe if proper work precautionsare taken, but no one is safe if good workattitudes are ignored.

SAFE EQUIPMENT OPERATIONWelding equipment should not be usedunless exact operating instructionshave been received and understood.Manufacturer recommendations shouldbe followed at all times. Attempting tooperate a piece of equipment withoutinstruction may not only damage theequipment, it could result in a seriousinjury.

Operators of equipment shouldwear appropriate personal protectiveequipment, properly maintain theequipment they are operating, and usethe safety features of the equipment.All welding equipment is safe to op-erate providing it is used in the propermanner. Malfunctioning welding equip-ment should be repaired by a trainedservice technician.

Confined SpacesA confined space permit is necessarywhen repair welding is carried out inspecific physical situations. A con-fined space is a workspace that hasany of the following features: I) it islarge enough and so configured thata person can bodily enter it and per-form assigned work , 2) it has limitedor restricted means for entry or exit,or 3) it is not designed for continuousoccupancy.

Examples of confined spaces in-elude tanks, silos, storage bins, hoppers,vaults, pits, and trenches. Specific safetyprecautions required when working in a

confined space include having a stand-by person available, guarding openings,using adequate ventilation, and per-forming oxygen content checks.

Welding and cutting operations per-formed in confined spaces create spe-cific safety hazards. For instance, a leakin welding equipment can displace Iife-supporting oxygen levels . See Appen-dix. Some gases, such as argon, cannotbe detected by smell and in confined orlow-ventilated areas build to toxic lev-els. Welding, flame cutting, or allied pro-cesses should never be started unt ilsafety precautions are addressed. Weld-ing safety procedures are developed toavoid hazards that might be presentfrom welding operations. These includehazards of welding products, fumes andgases, electric shock, noise, heat, bums,and radiation . The welder must be sat-isfied that the confined space entry pro-cedure and paperwork are satisfactory.If not, the welder has the right to refuseto perform the work until remedial ac-tions are taken.

A permit is required when a con-fined space contains atmospheric haz-ards that have the potential to causeserious physical harm to a welder. SeeAppendix . A permit-required confinedspace is a confined space with one ormore of the following characteristics: It contains or has the potential to

contain a hazardous atmosphere. It contai ns a material that has the

potential to engulf the entrant. It has an internal configuration

such that the an entrant could betrapped or asphyxiated by inwardlyconverging walls or by a floor thatslopes downward and tapers to asmaller cross section.

The confined space contains anyother recognized serious safety orhealth hazard.

o Confined space permits are issued jor aspe cific period of time . Work must b~completed in the alloted time oranewpermitmust be obtained.

When working in aconfined space, havea s tand -by personava ilable to ensure asaf e environment.

A WARNINGAny weld ing equipmentmalfunctions shall bereport ed to the superv isor.

Welding Safety ~ II

A WARNINGEven with proper ventila-tion . a res pirator sho uld beused when metals thai giveoff roxie fumes are welded .

Figure 2-3. A ventila tion syst emis required 10 rnl1OI'C tox ic [utnes.smoke , (lilt! dust caused bywe lding,

12 l' Weldin g Skill ."

Under any or all of these conditionsa permit sys tem is required in whichworker entry into the confined space isregulated. The employer must developpro cedures for preparing and iss uingpermits to enter, work insid e, and re-turn the confined space to service at theend of the job. Permit-required confinedspaces require assessment of entry pro-cedures in compliance with OSHA stan-dards prior to entry.

A non- permit confined space is aconfined space that doe s not conta in,or have the potenti al to contain, anyhazard s ca pa ble of ca us ing death orserious physical harm. Conditions canchange as tasks such as welding occur.

VentilationWelding should only be performed inwell-ventilated areas. There must be suf-ficient movement of air to prevent anaccumulation of toxic fumes Of, possi-bly, a defi ciency of oxygeo. All windor air movement (ventilation) should beacross the body, not from in front orfrom behin d. Front- and rear -di rectedair movement causes wind tunnels (roll-ing) in front of the body and into theresp iratory tract. Adequate ventilationbecomes extremely critical in confinedspaces where dangerous fumes, smoke,and du st are lik ely to co llec t. Whenworking in a shop, the installed venti-lation system is usually not adequate tovent the toxic fumes generated by weld-ing. Additiona l ventilation is required,by the use of either a respirator, fans, oran exhaust system. See Figure 2-3.

An ex haust system is necessary tokeep toxie gases belo w the prescr ibedhealth limits in areas where much weld-ing is performed. An adequate exhaustsystem is espec ially necessary whenwelding or cutting zinc, brass, bronze,lead, cadmium, or beryll ium. This in-cludes galvanized steel and metal paintedwith lead-based painl. Fumes from thesematerials are toxic and hazardous. Evenwhen ventilation is provided, a respira -tor should be used when metals that giveoff toxic fumes are to be welded. Nearthe work area, to xic fum es may bebreathed in before they can be extractedby the ventilation system. See Figure 2-4.

Srll.'from IIImwjiu",,,,.illg Cr>.Figure 2-4 . A respirator sho uld b e wort/ whe nwelding metals ,hal {,roell/('e toxic [ utnes.

PERSONAL PROTECTIVEEQUIPMENTPersonal Protective Equipment is a de-vice worn by welders to prevent injury.All personal protective equipment mustmeet requirements specified in OSHA29 CFR and othe r applica ble sa fetystandards. All welding and cutting op-erations generate sparks and/or ultra-violet and infrared ra ys. Sparks maylead to se rious burns, and ultravioletand infrared rays are extre me ly dan -gerous to the eyes and skin. A weldermust be aware of possible dangers tothe body during any welding or cuttingoperation and learn the safe practic esfor personal welfare. Suitable eye pro-tection, clothing, and ear protection arenecessary. See Figure 2-5.

ELECTROMAGNETIC SPECTRUMSources Region Wavelength

AtomicNuclei

Accelerators

Gamma Rays301m

MagnetronKlystron

-------------4-------3 cm

Microwaves

--- - -- -- - -- - - 1----

ElectricCurrents

TelevisionFM Radio

AM Radio

LongwaveRadio

3m

300 m

30 km

Nrderman. tnc.

Figure 2-5. The my .I' generutrd by weld ing are harmful to workers. A welder shautd always Wl'ar suitable personal protective equipment 10 pro/eelagainst the 1I/(/"(1I';011'( (11/(/ infrared rays generated during welding.

Weldin g Sa!'ely @ 13

re:::: I lVhetm eldillKat...avs~ wear safety glasses. = with approved filler

pla tes.

Eye ProtectionEye protection is essential for welders.Radiation prod uced by weldi ng andcutting may be harmful to the welder.Radi ant energy may be ioniz in g(suc h as X-ray s) or non-i oni zing(such as ul traviole t, visible , or in-frared light) . Radiation can burn theskin and damage the eyes. The effectsdepend on the radi ant energy wave -len gth and intensity. and exte nt ofexposure .

Most arc welding and torch cuttingprocesses produce non-ionizing radia-tion such that eye protection is neces-sary. A we ld ing arc should only beviewed through filter plates that meetthe requirements of the American Na-tional Standards Institute (ANSI) .Z87.1, Practice f or Occupational andEducational Eye and Face Protection.Welders should always be alert for re-flections from welding arcs. Passersbycan be protected by we lding screens,curtains. or remaining an adequate dis-tance from the job.

Cutt ing and welding opera tio nsproduce sparks and hot slag that canbe projected from the welding surfacetoward the welder. Proper protectionmust be used to prevent inj ury to theeye. Eye protecti on is avail able withpre scription lenses for welders whonormally wear glasses . Some weldersmay prefer to have prescripti on lenseson the safety glasses becau se wearingglasses. safety glasses. and a helm etmay be unwieldy.

Helmets . Welders also wear protectivewe ld ing he lme ts wi th special filterplates or filter glasses to protect againstinjury and expo sure to ultraviolet andinfrared ray s. Helmet de signs allo wboth hands to be used for we ldi ng.Helmets are made to fit over the head.attach to hard hats, or be held by hand.An adj us table he adband inside thehelmet provides a comfortable fit. Thehelmet may be sw ung up when notwelding . The hand-held helmet is usedby observers. See Figure 2-6.

Milum", M,mufm",u, iI1JtCo. Uobur/ ",,,Idr' s Sri/JIm", M,m"!",:,..n,,x Co.

AUTO DARKENING FLIP FRONT FIXED SHADE COMPACT

Figure 2-6. A welding helmet protects tke welder from infrared and ultraviolet rap. and hOI sparks.

14 ~ Welding Skills

Welding helmets should be in goodcondition since openings or cracks canallow arc light through. A cover plateshould be placed on the outside of thefilter plate to protect it from weldspa tte r. The filter pl at e should hemade of tempered glass so that it willnot shatte r if hit by flying objects,Filter plates are mark ed showing themanufac turer, the shade number, andthe letter H indica ting they have beentreated for impact resistance.

Helmets may have fixed or adjustablelenses. Auto-darkening lenses darken inless than a hundred-millionth of a secondwhen arc light strikes the filter.

Colored lenses should be examinedand replaced if cracked. Lenses comein different shades, depending on thewelding to be done. For oxyacetylenecutting operations, a #5 shade may beused. For arc welding at 75 A (amps) toZOO A, #10 shades or higher should beused. In general, for welding operations,the recommended shades , based onwelding current, are as follows:

Shade 10 - 75 A to ZOO A Shade IZ - ZOO A to 400 A

Shade 14 - over 400 AColored lense s ar e prot ected by

clear glass or plastic cover plates. Theclear lens is placed ove r the coloredlens inside the face plate. During thewelding process, sma ll particles ofmetal fly upward from the work andmay lodge on the lens, distorting thewelder's view. However, clear visionis necessary at all times during weld-ing, so the clear plastic cover plate mustbe replaced when it becomes spattered.Although the methods of inserting coverplates differ among manufacturers,changes can be made ea sily andquickly. The cover plates are inexpen-sive and can be purchased from anywelding supply dealer. Always followmanufacturer recommendation for theappropriate lenses and cover plates.

Safety Glasses and Goggles. A weld-ing helmet does not provide total pro-tection to a welder, so safe ty glassesandlor goggles should he worn at alltimes when welding. Dur ing shieldedmetal arc welding, a thin crust (slag)forms on the deposited bead. This slagmust he removed from the weld. Whenremo ving the slag, tiny particl es maybe deflected upward. Becau se o fstresses that build up in the weld, slagmay occas ionally po p off the we ld.These particles can cause serious eyeinjury unless proper eye protection isworn. See Figure Z-7.

-

&11.,'",m M,u"

[1 111 add ition 10 ap-~ proved work clothes.. = heavy-duty welding

requires a leatherjuckrt or apron nndleather gauntlet-type,::IOI't',f.

mate rial. Pant cuffs or clothing withopen pockets that can catch and re-tain molte n met al or spa rks sho uldnot he worn. Work boots, leather leg-gings, and fire-resistant gloves shouldbe worn. Pant legs should be worn overthe outside of the boots. Helmets andhand shie lds tha t pro vide protectionfor the face, neck, and ears should beworn, as well as a protective head cov-e ring . Approved work clothes, aheadcap, welding helmet , work boots,and gloves are requ ired for all ligh t-dut y weld ing and cutt ing operati ons.In add ition, heavy-dut y weld ing re -qu ires a leather jacket or leather apronand leather gauntlet-type gloves .

Work Clothing, Work clothes worn bywelders should be made of natu ralmaterials such as leather. wool, or cot-ton as these material s have a higherresistance to burning. Synthetic mate-rials such as polyester should never beworn. as they melt and burn easily, andcan cause severe injury to a welder.

Covera l ls o r wo rk cloth esshould be heavy enoug h to prev entin fr a red and ultraviolet rays fro mpenetrat ing to tbe skin. Cuffs on pantsshould be turned down or e liminatedand pockets removed to prevent mol-ten meta l from catching in the clo thes.Sleeve s and co ll ar s sho uld be keptbuttoned . See Fig ure 2-8.

Gloves. Gloves should be worn to pro-tect the hands from ultraviolet rays andspattering hot metal. Glove s are alsouseful when picking up metals that havebeen welded. The red hot color of metalfades and metal retu rns to its originalgray color quickl y; however, metal re-mains hot for some time after weldingand cannot be identifi ed as hot simplyby looking at it. Gloves should be womat all times when work ing with meta lthat may be hot to prevent the hand sfrom being burned.

Severa l types of gloves are avai l-able for welding. Leather work glovesand gauntlet-type gloves both prov ide

SLEEVEBUTTONED~

GLOVES -

/

COLLAR BUTTONED

~HELMET

l1r~ u,..."lnElrt:tri."c."",,

protection. Gloves should be flex ibleenough to permit proper hand move -ment, yet not so thin as to allow theheat to penetrate easily. See Figure 2-9.

Leather Jackets and Aprons. A leatherjacket or apron is recommended whenwelding, as spatter might cause injury.A leat her apron offers the be stprotection from ho t spa tt e r. Insituations where there may not be anexcessive amo unt of me tal spa tt er,suitable cove ralls (fire-retardant) maybe worn to protect the clothing.

GlovesFigure 29

S",i rh E'I" /{"" rnlWORK

GAUNTLET-TYPE

Figure 2-9. Always wear gloves when welding undcutting 10 protect ,I/(' hands f rom ultraviolet raysand spatter:

Work Boots. Work boots must beapproved safety shoes or boot s madeof leather or other approved mater ial,with a reinforced or steel toe to preventimpac t inju ries . Me tatarsal (in step)pro tec tio n sho uld also be worn toprevent slag material or sparks fromdropping into the shoes . Street shoesmust never been worn, regardless of thematerial from which they are made.

Ear ProtectionSo me we ld ing o perations, such aschipping, peening, air carbon arc goug-ing, and plasma arc cutting, producehigh level s of noi se. Engi ne- drivenge nera tors ca n also be noi sy. Exces-sive noise affects hearing capability.It may be a temporary loss from whichthe ears recover if remuved from thenoise source. However. if a person isexposed to this same noise for long pe-riods of time, the hearing loss may be-come permanent. The time required todevelop permanent hearing loss de-pends on various factors. Ear plugs orear muffs must be used when en gi-nee ring co ntro ls (such as shielding)are not effective in reducing exce s-sive noise.

Ear plugs and ear muffs are suppliedby the employe r in sit ua tions whereworkers are exposed to extreme noise.Earplugs are a device inserted into theear canal to reduce the leve l of noisereac hing the ea rdrum . Earp lugs aremade of moldable rubber, foam, or plas-tic . Ear muffs are a device worn overthe cars to reduce the level of noi sereaching the eardrum. See Figure 2- 10.

Safe noise levels and levels at whichhearin g protection is requ ired are in-dicated by regulations deve loped bythe Enviro nmental Protect ion Agency(EPA) and OS HA. Ear protect ion de-vices are rated for noise red uction tomaintain permissib le noise levels . Aliaise reduction rating number (NRR)is a number that indicates the noiselevel reduct ion in decib els (dB).

Never place jacketsor shirts over oxygenor gas cylinders. Gascan leak underclothing lind start afi re.

Earprotection S/U)/{!dhe wom when weld-ing as the excessivenois e generated bywelding a lii affechearing.

Weldin g Safety l' 17

Ftgu re 2- 10. Ear pr otection". '. "., "should be used for weld ing op -

erations. .fueli tIS c'hippi'l!:. pUll-ing , carbon tire air gouging, lI lIdplasma arc cutting. IJUIt producehigh levels of nois e.

18 ~ Weldin g Skil ls

EAR PLUG

For example, an NRR of 27 meansthat the noise level is red uced by 27dB when tested und er fac to ry cond i-tion s. If a facto ry has a noi se levelof 95 dB, the exposure lim it withoutear protection is 4 hr. For workers ex-posed to those noise levels for an 8 hrshift, ea r protection is required. Ea rplugs commonly have an NRR of about27, whic h wou ld red uce the noi selevel from 95 dB to 68 dB. Sixty-eightdecibe ls is a moderate intensity andwell within the per missible ex posu relimi t for an 8 hr shift, thus reducingthe danger of hearing impairment. SeeFigu re 2- 11.

HAZARDOUS SUBSTANCECONTAINERSFumes and gases are prod uced bywe ld ing and cutt ing and so me areharmful to a welder's health . Problemsare compounded by welding or cuttingon surfaces contaminated by chemicalsor co rrosion products . Fu mes andso l id part icles orig ina te from thewelding process. Gases are generatedduring wel di ng, or may be producedby the effec ts of weldin g radiation onthe surrounding environment.

EAR MUFF

Adequate ventilation must be avail-able to remove fume s from the workarea. Where ventilation may be inad-equate, ai r sampling sho uld be usedto det erm ine where corrective mea-sures are to be applied.

Hazardous substances include thosethat are combustible, toxic. or corrosive.Hazardous substances may be prese ntin a conta iner havi ng prev iously heldany of the followi ng: a volatile liquid that releases

potentially hazardous, fla mma ble,and/or toxic vapors at atmo sphericcon ditions

an acid or alkaline material that reactswith metals to produce hydrogen

a nonvolatile liquid or solid that atordin ary temperatures does notrelease potentially hazardous vapors,but does so if the container is heated

a du st cloud of fine ly div ided air-borne particles that may still bepresent in an explosive concentration

a flammable or toxic gas

Cleaning Hazardous SubstanceContainersFor maximum sa fe ty, only qualifiedpersonnel shall designate the containercleaning method. The cleaning method

120 thu nder , artillery ,Deafening 110 nearby riveter100 loud street noise,

Very Loud 90 noisy factory,unm uffled truck

80noisy office,

Loud 70 average street noise,60

average factorynoisy home,

Moderate 50 average conversation,quiet radio

40 quiet home,Faint 30 private oHice,

qu iet conversation20

whisper,Very Faint 10 sound proof room,

0 threshold of audibility

6432

y,1,4 or less

92959710010210510711011 5

NOISE REDUCTION RATING: *Ear Plugs = 27 dBEar Muffs = 32 dB:t: typical , varies by manufactu rer

Example: A noisy factory has a decibel level of 95 dB thatwith ear plugs can be lowered to 66 dB. which is of moderateintensity but well within permissible exposure times.

in nrst in decibe ls (dB)

PERMISS IBLE EXPOSURE TIMES

Flgure 2-- 11. Sar protection reduces tile decibel level to which the eardrums art' exposed. reducing the chance (if damage to the worker's hearing.

used depends upon the substance pre-viously held in the container. The wa-ter method of cleaning is used whenthe substance is known to be read ilysoluble in water. The residu e can beremoved by completely filling the con-tainer with water and draining severa ltimes . Whe n the substance originallyheld in the container is not rea d ilysoluble in water, additional methods of

cleanin g the container are ava ilable.inc lud ing the hot chem ical solution,steam , mechanical clean ing, or chemi-cal clean ing methods. Occasio na lly,combinations of all methods of clean-ing must be used prior to welding orcutting. Care must be taken to protectperson nel and to preven t hazardousrea ctions when co mbi ning cleani ngmethods.

Weldin g Safety ~ 19

A WARNINGA container that has heldunknown subs ta nces shouldneve r be cl ea ned andwelded becnnse unknownsafety hazards are involved.

20 ~ Weld illg Skills

Hot Chemical Solution Method. Theho t che m ica l so lut io n method use str isod ium phosp hat e (a stro ng wash-ing powder) or a co mmerc ia l caus-ti c c leaning compound di sso lved inhot wa ter. T he c lea ni ng age nts aremixed wi th hot wa te r an d added tothe co nta iner to be cleaned. The co n-tainer is then fi lle d with water andstirred unt il the chemica ls have beencl eaned from the contai ner.

Steam Method. The steam method forcleaning container s uses low-pressuresteam and a hot soda or soda ash to re-move substances. The cleaning age ntsare added to th e con tainer and theconta iner is filled with live steam andstirred unt il the chemicals have beenrem oved from the container.

Mechanical Cleaning Method. Themech anical cleaning method is ge ner-ally used when scaly, dry, or insolub leresidues have been left on the surfaceof the container. Mechanical cleaningma y be performed by scraping , sandor gri t bl asting. high-pressure wa te rwashing. brushing, fill ing the con tainerone-quarter full of clean dry sand androlling it on the floor, or any method inwh ich the contaminant can safe ly bedislod ged . Du ring mechanical clean-ing, the container should be groundedto minimi ze the possibility of sta ticcha rge build up and spark charges .

Chemical Cleaning Method. Thechemical cleaning method is gen era llyused when the co ntain er has insolubledeposits or when it cannot be mechani-ca lly cl eaned. Care must be used inselecting a chemical solvent; some sol-vent s may be as hazardous as the de -po s it s they ar e int ended to remove.Wh en selecting c hem ic al so lve nts ,con sult the man ufact urer of the ma -terial to be removed.

Container s shou ld be c he c ke dcarefully after an y cl eaning methodto ensure that all chemicals have beenthoroughly removed from the container.

As a final precaution after cleaning, acontainer should be vented and filledwith water before we ld ing or cutti ng.The co nta iner sho uld be arra nged sothat the container can be kept fill edto within a few inch es of th e po intwhere the we ldi ng or c utt ing is totake place, but not interfere with weld-ing. See Figure 2-12. When we ld ingor cutting on containers, observe thefo llowing safety pre ca ut ions: Vent the container to allow for the

release of air pressure or steam dur-ing welding .

Use a spark-resistive tool to removeheavy sludge or scale when scrap-ing or hammering.

Never use oxygen to venti lat e acontainer as it ma y start a fire orcause an ex plos io n.

VENT

WATERLEVEL~

"'i~lIre 2-12 . Conta iners x/lOuld be partiatlv f illedwith water before cutting or welding.

Never rely on sight or sme ll to de-termin e the safety of welding or cut-ting a closed co nta iner. A smallamo unt of residual flammable liq-uid or gas may not be detectable,but it co uld cause an expl osion .

Never weld or cut drums, ba rre ls,or tanks until the danger of fire orexplos ion has been eliminated.

Material Safety Data SheetsBefor e any conta iner is cleaned, thehaza rdou s charac teristics of the sub-stance previously held by the containermust be det erm ined . Informationabout the substance and safety pre-cautions to follow when working withthe substance are contained in a Ma-terial Safety Data Sheet (MSDS). A Ma-teria / Safety Data Sheet (MSDS) isprinted mat eria l that inc lude s d ataabout eve ry hazar dou s compo nentcomprising I% or more of a material' scontent and is used by a manufacturer,importer, or distributor to relay chemi-cal hazard information to the employee.

MSDSs are obtained from the sup-pliers of welding filler metals, fluxes,and gases. They should be kept on fileat a designated locat ion in the work-place. The information is used to informand train employees on the safe use ofhazardous materi als . See Figure 2-13.

If an MSDS is not provided, the em-ployer must write to the manufacturer,distributor, or importer to obtain the miss-ing MSDS. An MSDS has no prescribedformat but must contain certain infor-mation related to the chemical hazard,identificati on , physical and chemica lcharacteristics, tire hazards, reactivity andhealth hazard data, handling precautions,

I Material safety data.~ sheets include dat a.= a /unit n 'ery hoeard-OIlS compon ent (' 0111-prising 1% or more ofa material 's content.

MANUFACTURER fINFORMATION l SpringfieldChemical Products

1701 Hillman StreetPittsburgh, Pa 00740

MATERIAL SAFETY DATA SHEET

I~A. RED OXIDE PAlMER If_~_

-.... (50!!} 5!r5-6OOO 11_ I>:>urol

PRECAUTIONS ANDPERSONALPROTECTIVEEQUIPMENT REQUIRED

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HANDLING ANDSTOR AGEPRECAUTIONS

}DISCLA IMERSTATEMENT

}CHRONIC HEALTHHAZARD S

}REACTIVITYHAZARDS

}SPILL, LEAK, ANDWASTE DISPOSALPROCEDURE S

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22 l' Welding Skills

and control measures of the hazardou smaterial. MSDS files must be kept up-to-date and well organized to allow quickaccess to information in an emergencysituation. Employees should become fa-miliar with the MSDS for chemicals com-monly encountered on the job.

CUTTING SAFETYFires often occur during cutting opera-tions because proper safety precautionswere not followed. Sparks and falling slagcan travel great distances and can passthrough cracks in walls or floors out ofsight. Persons responsible for perform-ing or supervising cutting should observethe following safety precautions:o Never use a cutti ng torch wh ere

sparks will be a hazard , such asnear room s containing flammablema terial s, especia lly dipping orspraying rooms.

o Sweep floors clean and wet thembefore beginn ing cutting. Providea bucket or pan containing wateror sand to catch dripping slag.

o Use fire-resistant guards, partitions,or screens if cutting must be per-form ed near flammable material sthat cannot be moved.In greasy, dirty, or gaseous atmo s-pheres, extra precautions should betaken to prevent ex plos ions thatcan res ult from electric sparks oropcn fires durin g cutting or weld-ing operations.

o Keep flame and sparks away fromoxygen cylinders and hoses.

o Keep combustible materials at least35' away from any cutting or weld-ing operations.

Never cut near ventilators.o Never use oxygen to dust off

clothing or workpieces.o Never use oxygen as a substitute

for compressed air.

o WeMers arefrequently exposed to hazardoussituations. Personal p rotective equipmentsuch as safety shoes. goggles. helmets withprotectivelenses. andotherdevicestopreventinjury should always be used.

OXYACETYLENE WELDING SAFETYSafety precauti ons for oxyacetylenewelding cover the proper handling ofcylinders, operation of the regulators,use of oxygen and ace tylene, care ofwelding hoses, testing for leaks, andlighting a torch. All safety regulationsshou ld be followed.

Additionally, all piping and fittingsused to co nvey gases from a cen tra lsupply system to work stations mustwithstand a minimum pressure of 150psi. Oxygen piping may be black steel,brass, or copper. Only oi l-free com-pounds shou ld be used on oxygenthreaded connections.

Piping for acetylene must be wroughtiron. After assembly, all piping must beblown out with air or nitrogen to removeforeign materials before first use. Observethe following basic rules for the safe han-dling of oxyacetylene equipment:o Locate the nearest fire extinguisher

before performing any welding orcutting opera tion.

o Keep oxyacetylene equipment clean,free of oil, and in good ope ratingcondition. Neve r handl e cylinderswith oily or greasy gloves.

o Keep heat, flame, and sparks awayfrom combustibles.

o Prevent leaks in oxygen and acety-lene cylinders.

o Open cylinder valves slowly.o Purge oxygen and acetylene hoses

before lighting torch.o Never move cylinders without pro-

tective caps in place.

ARC WELDING SAFETYArc welding processes include shieldedmetal arc welding (SMAW), gas tung-sten arc welding (GTAW), gas metal arcwelding (GMAW), and flux cored arcwelding (FCAW). General safety mea-sures are indicated for these areas sincearc welding equipment for each processvaries considerably in size and type .Equipment may range from a small por-table SMAW machine to a highly

mechani zed production spot weld ingmachine. Manufacturer recommen -dation s should be foll ow ed for theequipment used. See Figure 2-14.

Electric shock can be fatal. Liveelectrical part s should not betouched. and manufacturer instruc-tio ns and all recomme nde d safe typractice s mu st be follow ed . Faultyinsulation, improper grounding , andincorrect operation and maintenanceof elec tr ical equipment are typicalsources of danger from electric shock.Use only welding machines that meetrecog nize d nati onal standards, suchas those ident ified by the Nati onalElectrical Manufacturers Associ ati on(NEMA), NEMA EW-I, Electric ArcWelding Pow er Sources .

" : ~..~.~.~~~~Tnermadvnr industries. fn< .

Proper workpiece connections 10 complete a welding circuit prevent electric shockand personal injury.

Figure 2-14. Following commonsafely precautions reduce s thechalices of an accident oc cum neduring welding.

LOCATE POWER DISCONNE CT NEARWELDING MACHINE

DO NOT PICK UP HOT WORKPI ECES

ATIACH WORKPIECE CONNECTIONSSECURELY

Tht' UN: ,,,,, Eltric Conrf'

Welders who fo llow all safetv requirements ensure a safer work environment forthemselves and others in the work area.

Always lise insulatedelectrode holderswhen weld ing withSMAW to preventelec tric shock amiinjury.

All el ectrical equi pment and theworkpiece should be grounded. Theworkpiece lead must not be used asa ground and is used on ly to com-plete the welding circuit. The correctsize leads for the welding applicationshould be used . Sustained overload-ing causes failure of the welding leadsand results in electric shock or fire haz-ard. All electrica l connections shouldbe tight, clea n, dry, and in good con-dition. Poor connections can overheatand melt , or produce dangerous arcsand sparks. Water, grease, or dirt mustnot be allowed to accumulate on plugs,sockets, or electrical units .

Onl y insulated electrode holdersshould be used for SMAW. Semiauto-matic welding guns for continuous wireprocesses should use low-voltage con-trol switches so that high voltage is notbrought into the electrode holder in thewelder' s hands. In fully automaticequipment, higher vo ltages are per-mitt ed because they are inaccessibleto the operator during th e normalwelding sequence.

High open circ uit voltages shouldbe avoided. When several welders areworking with arcs of different polar-ity, or when a number of AC machinesare being used, the open circuit volt-ages can be additive and increase theseverity of the shock hazard .

Elec tro de leads and workpiecelead s sho uld not be co ile d aroundwe ld ing mach in es or th e welde r.Electrode holders should not be hungwh ere th ey ca n accidentally comeinto contact with the other side of thecircuit. Electrodes should be removedfrom the electrode holder when not inuse. Power cables coming into a weld-ing machine should not come into con-tact with welding leads. The weldingmach ine mu st be kept d ry and if itsho uld become wet it must be driedproperly by electrical maintenance per-sonnel. In addition, the work area mustbe kept dry. Welders should never workin water or damp areas becau se waterreduces a welder 's resistance and in-creases potential electrical hazards. Thewelder should stand on a board or in-sulated platform . The following safetyrules are common to most arc weldingopera tions : Install welding equipment accord-

ing to pro vision s of the Nat ionalElectrical Code".

Use we lding machi nes equippedwith a power disconnect switch lo-cated at or near the machine so thepower can be shut off quickly.

Ens ure that the wo rk are a isgrounded. Do not ground to pipe-lines carrying gases or flamm ableliquids.

Use proper safety guards when us-ing press -type welding mach ines.

Use suitab le spark shields aroundequipment when flash welding.

Turn OFF the we ldi ng machine ,pull the power disconnect switch,remove the electrode, and hang theelectrode holder in its designatedplace when welding is completed.

24 1 WeidinK Skills

Inspect welding cables for cuts,nicks, or abras ions.Do not pick up pieces of metal thathave just been welded or heated,Do not ma ke repairs to weldingequipment unless power to the ma-chine is OFF. The high voltage ofarc welding machines can cause se-vere, eve n fatal injuries.Do not change polarity when themachine is und er load. The ma -chine should be idled and the cir-cuit open; otherwise, an arc mayoccur, burning the contact surfaceof the switch and severely burningthe welder.Do not overload welding leads oroperate a mach ine with poor con-nections. Operati ng with currentsbeyond the rated cable capacitycauses overheating .Neatly arrange the welding leadsand secure the proper connections.Do not weld on hollow (cored) cast-ings unless they have been properlyvented; an explosion may occur.

Combustible materia ls shou ld beremoved from the work area, or thelocation of the work must be at least35' away from combustib le material s.If ne ithe r is possible, combustiblesshould be protected with a cover offire-resistant materi als. A fire extin-guis her should be kept near cuttingand welding operations at all times. Ifthe risk of fire is great, fire watchersshould be avail abl e. If possibl e, thework area should be enclosed with por-table, fire-resistant screens. Welding orcutting should not be done where dan-gerously reactive or flammable gasesarc present.

o Explosion. fire. or other health hazardsmay result if weld ing or cutt ing ;.'1performed O il conta iners that are notf ret' of hawrdou s subs tances. Nocontainer should be presumed to heclean or sufi'. Containers can be madesafe f or welding ami cutting provided thenecessa ry steps ami safety precautionsare/of/own}.

A CAUTIONCombustib le materialsmust he loc ated at least 35'away from any area wherewelding is 10 be done.

PREVENTING FIRESWelding operations expose welders toheat, sparks, and flam e. Precau tio nsshould be taken to ensure that the jobsite is safe and that adequ ate fire pre-vention strateg ies are in place.

Fire may be produced by moltenmetal, sparks, s lag, and hot work sur-faces. Sparks may cause fire or explo-sion if precauti onary measures arenot used. Sparks can pass through orbeco me lod ged in crac ks , clothing,pipe holes, and other small openin gsin floors and part itions. Typical in-door combus tib le materi al s arefloor s, partitions, roofs, and build-ing content s, Indoor combus tiblematerials may cons is t of wood, pa-per, clothing, plasti cs, and chemicaland flammabl e liquid s and gases. Ex-amples of out side combustible mate -rials arc dry leaves, grass, and brush.

Milia /",./ri, ' M",,,,r;U'luri"K C"ml',myWelding shops should be equipped with a fi re extinguisher tha t is loca ted near thework area fo r ('( 1.\")' access in caw' ofjire.

We/dill R Safety ~ 25

"'i~ure 2-15. Fire extinguishe r... lire rlus...ified l I S A. R. C. D. und K.

K

mWOOd Paper Rubber Plastic Cloth

r:!.Flammableliquids- Grease GasesIJJIIII Electrical,.

Combustible

*metals

Magnesium- Titaniurn Zirconium Sodium

IICommercialcookinggrease----

Water Dry chemicals

Dry chemicals Foam Carbon dioxide

Non-conductingagent such as: Dry chemicals Carbon dioxide

Extinguisherparticular totype of metal

Wet chemicals Dry chemicals

T he Nationa l Fi re ProtectionAssociation (NFPA) classifies fires intofiv e ty pes: A, B, C, D, and K. T heclassifications are based on thecombustible materi al and the type ofextinguis her requ ired to put out thefire. Extinguis her classifica tions canalso be identified by co lor and shape.See Figure 2-15 .

Class A

A Class A fire may be caused by mostco mbustible mater ials, such as wood,paper, rubber, plastic, and clo th. ClassA fires are the most comm on type offire. A Class A fi re ex ti nguis he r isidentified by the co lor gree n inside atriangle shape. Class A fires can be ex-tinguished with water or dry chemicals.Carbo n d ioxide , sod ium, and pot as-sium bicarbonate chemicals should notbe used on a Class A fire.

Class BA Class B fire is caused by flammab leliquids, gases, or grease. A Class B fireextinguisher is identified by the colorred inside a square. Class B fires ca nbe ex tinguished with dry che micals .Foam and carbon dioxide extingu ish-ers may also be used .

Class CA Class C fire is an e lec trica l fire. AClass C fire ext inguisher is ident ifiedby the color blue inside a circle. Elec-trical fires requ ire a non-conductingagen t, such as carbon dioxide or drychemica ls, to ex tinguish them. Foamextinguishers or water should never beused on an electrical fire.

Class D

A Class D fire is caused by combustiblemetals, such as magnesium, titanium, orsodium. A Class D fire extinguisher isidentified by the color yellow inside astar. C las s D fires cannot be extin-guished with a common A, B, or C ex-tingu isher; the chemicals in common

26 ~ Welding Skills

extinguishers can int ensify the fire ,rather than put it out. Dry powder ex-tinguishers are available that are madespecifically for metal hazards.

Class KA class K fire is caused by grease incommercial cooking equipment. ClassK fire extingui shers coat the fire withwet or dry chemicals.

Common dry chemical extinguishersshould be available in case sparks fromwelding set other materials on fire. Thetwo basic types of dr y chemicalextinguishers are the stored-press ure

and the cartridge operated. A fir eextinguisher labeled ABC is composedof dr y chemicals and is capable ofextinguishing class A, B, and C fires. Afire extinguisher labeled either A, B, orC can only extinguish the fire for whichit is labeled. Using an improper fireextinguisher can have an adverse effecton a fire, making the fire worse ratherthan extinguishing it.

Welders must be particularly awareof the fire hazards involved in th emetals they are welding and ensure thatthe proper type(s) of extingui sher areavailable.

I . Weekly safety meetings are a convenient way for employers to discuss relevant jobsite safety issues and cnncerns.

2. When working in a confined space, have a stand-by person availabl e to ensure asafe environment.

3. When welding, always wear safety glasses with approved filter plates.4. For most arc welding operati ons, a #10 shade should be used . For oxyacetylene

cutting, a #5 shade can be used.5 . In addition to approved work clothes, heavy-dut y welding requires a leather jacket

or apron and leather gau ntlet-type gloves .6 . Never place jackets or shirts over oxygen or gas cy linders . Gas ca n leak under

clothing and start a fire.7 . Ear protect ion should be worn when welding as the excess ive noise genera ted by

welding can affect hearin g.8. Material safety data sheets include data about every hazardous component comprising

I% or more of a material' s content.9 . Always use insulated electrode holders when welding with SMAW to prevent electric

shock and injury .

welding Safety 0 27

I . What are some of the main causes of acc idents?2 . Why should all accidents be reported immediately?3 . How is it poss ible to become involved in an accident when playing aro und in the shop?4 . What may happen if we lding equipment is used without proper instructio n?5. What should be done if a ma lfunction occ urs in any welding equ ipme nt?6 . What general practice should be followed regarding ventilation when performing

welding?7 . Why should used containers be thoroughly cleaned and safety processed before any welding or

cuttin g is done?8 . Wh y do fires often occ ur during a cutting operation?9 . What are some precauti ons that should be taken when using a eutting torch?

10. Wh y must we lders wear pro per personal protecti ve equipment when welding?II . A dry chemical fire extinguisher can be used to extinguish which class(es) of fire?12 . What class of fire extinguisher should be used for a fire involving burnin g metal?13. What is the purpose of an MSDS ?14. Why should a welder never look at an electric arc without eye protection?15 . What determines the correct shade of lens for use during welding?16 . Why should shaded lenses be covered with clea r plast ic lenses?17. Wh y are safety glasses requ ired when welding?18 . Wh y should leather gloves be worn when welding?

28 ~ Welding Skills

Engineers and designers consider all/actors in the design ofa weld joint to ensure safety and efficiency. Thesefactors include load requirements 0/ the weld; the adaptability (if the joint for the product being designed orwelded; the accessibility of the weld; the type of load 011 the weld; the intended [unction of the structure;gove17ling codes and specifications; and economic considerations such as the cost ofpreparing the joint.

Welded joints are used in virtually every industry. In the building industry. welds are used to join structuralelements such as COIUIllIIS, trusses, girders, and other structural components.

WELDING TERMINOLOGYBefore proceeding with any weldingoperation, we lde rs mu st und erstandcommon welding term s.

The base metal is the metal or alloythat is to be welded . An electrode is acomponent of thc welding circuit thatconducts electrical current to the weldarea. Electrodes may be co nsumableor nonconsumable, depending on thewelding process. Some elect rodes,

SINGLE BEADFROM ONE PASS

SINGLE PASS

such as tho se used in shie lded metalarc welding, are covered with a flu xco ating .

A weld head is a weld that result sfrom a weld pass. A weld pass is a singleprogression of welding along a weldjoint. See Figure 3- 1. A single passweld requires only one weld pass. Whenlaying a bead in a mult iple-pass weld,each weld pass builds on the previouspass. The movement of the heat source

BASE METAL

PASS 2

MULTIPLE PASS

Figure 3 1. When layillf.: (I bead. each pa.u builds 0 11 11Ie previous 1'1iSS. The mon'lII ell1 of the welding heat ,wmrn' creates rip/,l l'S (H the In-adis deposited.

29

creates ripple s as the weld bead is de-posited . A ripple is the shape withi nthe deposited bead caused by the move-ment of the welding heat source .

A crater is a depression in the basemetal that is made by the welding heatsource at the ter mination of the weldbead. Joint pen etration is the depth ofthe weld metal from the weld face intothe joint. The joint penetration measure-ment does not include the weld rein-forcement measurement. See Figure 3-2.

Weld reinforcement is the amount ofweld metal in excess of that required tofill the joint. Root reinforcement is rein-forcement on the side opposite the oneon which weldin g took place. Face re-inforcem ent is reinforcement on thesame side as the welding.

The mot face is the portion of thegroove face within the joint root. Themot opening is the di stance bet weenjoint members at the root of the weldbefore welding. The root opening mustbe accurate so that excess we lding isnot necessary. Weld width is the dis-tance from toe to toe across the faceof the weld. See Figure 3-3.

Fi~ure 3-2. A crater is II depres-sion made ill the bas e metal bythe we ld ing heat source . Jointp enetration is the depth of thecrater within the base me tal.

~ 7711.' root pass is the.~ initial weld pass that.= p rovides comple tepenetration throughthe thickness of thej oint member.

Figure 3-3. A proper rool open -;// 8 mu,\"1 be prepared 10 p reventeXCl'H welding . Weld reinforce-m ent is weld metal that ismounded across the weld width;

30 ~ Welding Skills

BASE METAL

,rWELD(' REINFORCEMENT

-L

T--.LT--ROOT

REINFORCEMENT

...DIRECTION OFWELDING

The weld toe is the point where theweld metal meet s the intersect ion ofthe base metal and the weld face. Thetoes are the points where the base metaland weld metal meet. The weld face isthe ex posed surface of the we ld,bounded by the weld toes on the sideon which welding was done . The facemay be either concave or convex. Theweld mot is the area where filler metalinte rsects the base metal and extendsthe furthest into the weld joint.

The actual throat is the shortest dis-tance from the face of a fillet weld tothe weld root after welding. The effec-tive throat is the mi nimum distance,minu s co nvexity, bet ween the we ldface and the we ld root. A weld leg isthe distance from the joint root to theweld toe. The weld leg is the size of afillet we ld made in lap or T-joints. SeeFigure 3-4 .

Filler metal is metal depo sited in awelded, brazed, or soldere d join t dur-ing the welding process. Fusion weld-ing is we lding that uses fusion of thebase metal or base metal and fi llermetal to make a weld . Fusion weld-ing is the mo st co mmon method ofjoinin g metals .

Welding progression conce rns theaddit ion of filler metal in a weld jointroot and beyond . A joint root is the por-tion of a weld joint where joint mem-bers are the closest to each other. A jointroot may be either a point, a line, or anarea. A mot bead is a weld bead thatex tends into or includes part or all ofthe joint root. A root pass is the initial

ROOT OPENING

ACTUALTHROATy

EFFECTIVETHROAT

WELDROOT

JOINTROOT

WELD FACE

WELD LEG

Figure 34. 11 fillet weld can hecross -sectioned to identify it svarious parts.

weld pass that provides complete pene-tration through the thickness of thejoint member.

Several weld beads (multiple-passweld) may be required to complete aweld. A multiple-pass weld containstwo or more weld beads.

WELD JOINTSA weld joint is the physical configura-tion at the juncture of the workpiecesto be welded. Weld joints must be cor-rectly designed and have adequate rootopenings to support the loads transferredfrom one workpiece to another throughthe welds. See Figure 3-5. The follow-ing are some basic considerations in theselection of any weld joint: whether the load will encounter

tension, compression, bending,fatigue, or impact stresses

how the load is to be applied to thejoint, i.e., whether the load is a static,impact, cyclic, or variable load

the displacement of the load inrelation to the jointthe direction from which the load isto be applied to the jointthe cost of preparing the jointWeld joint design is based on the

strength of the joint, safety requirements,and the service conditions under whichthe joint must perform. Additionally,

how stresses are to be applied duringservice, and whether tension, bending,or torsion is a factor, must be consideredin joint design. Joint design requirementsvary depending on whether the load isstatic, cyclic, or variable. Joints are alsodesigned for economy or accessibilityduring construction and inspection.The five basic weld joints used are thebutt, T, lap, comer, and edge joints. SeeFigure 3-6.

o When designing weld joints [orbuildings, consideration must be givento the effects of transverse shrinkage,which occurs in support columns as abuilding is constructed. Shrinkage canaccumulate if unaccounted for in theweld designs.

The Lincoln Elcari

Static Impact Cyclic or Variable

MOTION

I- -lI '-- LOAD

CONTACT

LOADCONTACT

DISPLACEMENT

TRANSVERSELOAD

LONGITUDINALLOAD

DIRECTION

Figure .1-5. WHden .~JlOltld be' [amiliar with how IO(ld.5 will impact welded joints ami 11";(11 the requirements for making the proper joint selection.

Figure 3-6. The fi ve basic weld: ," - ,-" "joims ll.H'di llweldillgantlle butt,

T, lap. COnlet; and edge.

EDGE

CORNER

LAP

T

BUTT

32 ~ Welding Skills

Butt JointsA butt jo int is a we ld j oint in wh ichtwo workpieces are se t approx imate lylevel to eac h other and are positionededge-to-edge . In a butt joint, the weldis made between the edge surfaces ofthe two sections to be fused . The jointmay be ei ther square or grooved. Buttjo ints include square , s ing le be vel ,single-V, dou ble-V, s ing le-U , a nddoub le-U butt joints . See Fig ure 3-7 .Butt joints are commo nly used in fab-ricating vessels and subassemblies andfor repair operations.Square Butt Joints, The square buttjoint is intended primari ly for mat eri-als that are 3/16" thick or less. Squarebutt joints req uire full and co mpletefusion for optimum stre ngth. For sub-merged arc we ld ing, material s up to%" thick wi th a mi nimum ga p of VB"can be welded. Th e square butt joint isreasonab ly strong in static ten sion butis not rec ommended when the joint isto be subjec ted to fati gu e or impactloads, es pecially at low temperatures .Preparati on for a square butt joint re-quires matching only the edges of theworkp ieces . Square butt joints are aninexpensive we ld joint opt ion.Single Bevel Butt Joints. A si ng lebeve l butt j oint is a parti al pen etrat-ing sing le bevel gro ove weld . It iswelded from one s ide and is gener-ally used o n metal s no more tha n1/ 2" thi ck .

Single-Y Butt Joints. A single- V buttjoint is used on metal from a" to s;.."th ick. Preparat ion fo r a sing le- V bu ttjoin t is cost ly bec au se a s pecia lbe veling o pe ra tion a nd mo re f ille rmaterial are required than for a squarebutt joint. A s ing le- V butt joint isstro ng in stat ic lo ading but , like thesq uare butt j o in t, is not parti cul arl ysu ita b le whe n s ubjec t to fati gue orimpac t load s at the we ld root.Double-V Butt Joints, A doub le-Vbutt j o int is su ita b le fo r a ll loadco nd it io ns . T he doubl e-Vi s o fte nspecified for stoc k that is heavier thanmeta l used fo r a s ing le -V. Hea vymetals that usc a doubl e-V joint aretypi c all y % " thic k or g rea ter. Formaximum we ld streng th, penetrati onmu st be complete o n both sides .

The cost of pre pa ring a double- Vjoint is hi gh er than the sing le- V. butusuall y less filler material is req uiredbecause a narrower groove ang le ca nbe used. To keep the joint s

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Welding Skills 01