Modern Welding

8/15/2019 Modern Welding

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3Welding Joints,

Positions, andSymbols

Chapter


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Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., nc.

'asic Weld Joints

• & "elder should understand the type and location of"elds needed by reading the "elding symbols

• & "eld #oint refers to ho" the parts are assembledprior to the "elding

• (he item to be #oined is base metal or base material


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'asic Weld Joints

• (here are fi!e types of #oints used in "elding – 'utt – $ap – Corner – (-Joint – )dge

*&merican Welding Society+


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'utt Joint

• 'utt #oints are used "hen parts are #oined edge-to-edge

• )dge preparation refers to ho" the edges areshaped prior to "elding

• & groo!e "eld is made by fusing molten filler metalinto a butt #oint


7/47Permission granted to reproduce for educational use only.© Goodheart-Willcox Co., nc.

'utt Joint

• (he !arious parts of a groo!e #oint ha!e names – Groo!e face – Groo!e angle – 'e!el angle – Weld root – oot face



'utt Joint

• arious terms are used to describe a completedgroo!e "eld

– Weld face – ace reinforcement – Weld toe – oot reinforcement – Joint penetration – Weld si/e



$ap and Corner Joints

• & lap #oint is formed by t"o o!erlapping pieces ofbase metal

• & corner #oint is formed by placing t"o pieces ofbase metal perpendicular or at an angle to oneanother

– nside corner #oints are "elded along the inside of the #oint

– 0utside corner #oints are "elded along the outside edgeof the #oint



(- Joint

• & (-#oint is formed by t"o pieces of base metal thatare at an angle of approximately 12 3

• (he edges may be prepared as a s%uare, be!el-groo!ed, J-groo!ed, or flare-be!el-groo!e #oint



)dge Joint and lange Joint

• &n edge #oint is formed "hen the surfaces of t"opieces are in contact and their edges are e!en

• & flange #oint is formed "hen the edge of one ormore pieces is bent to form a flange


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(ypes of Welds

• & "eld is a fused #oint bet"een t"o or more piecesof metal or nonmetal

• illet "elds are made at the intersection of asurface and an edge or in a corner "here t"osurfaces meet

• & groo!e "eld is made in a groo!e or gap bet"een

t"o pieces of metal



(ypes of Welds

• & fillet "eld is made up of three primary dimensions – Weld si/e – )ffecti!e throat – $eg



'ead Welds and Weld Passes

• & "eld bead is one "eld pass of filler metal that isadded to a "eld #oint

• (he first "eld pass is the root pass• (he second "eld pass is the filler pass• (he final "eld pass is the co!er pass• Generally, a "eld bead should not be thic4er than

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Stringer 'ead and Wea!e 'ead

• & "eld bead may be a stringer bead or a "ea!ebead

• & stringer bead is used "hen a standard bead "idthis acceptable

• & "ea!e bead is used to create a "ider "eld pool• (he crescent motion is a popular pattern for a

"ea!e bead



Joint Geometry

• Joint geometry is defined as the shape anddimensions of a #oint, in cross section, prior to"elding

• Joint geometry is generally determined by a "eldingengineer or designer

• (he #oint geometry design should pro!ide space forthe "elder to reach near the bottom of the "eld

#oint



Preparation

• (he edges of thic4 metal are prepared for "elding – lame cutting – Gouging – 9achining

• Preparation allo"s the "eld to penetrate as deep asre%uired



Joint &lignment

• (he alignment of a #oint before"elding is !ery important

• & tac4 "eld is a small "eldused to hold pieces in alignment

• Parts may also be heldmechanically using clamps or

other de!ices

*'essey (ools :orth &merica+



Penetration

• & completed "eld #oint must be as strong as thebase metal

• (he "eld must penetrate deeply into the base metalto be strong

• Penetration is the depth of fusion of the "eld belo"the surface


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Welding Positions

• (he "eld axis is an imaginary line runninglength"ise through the center of a "eld


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(he Welding Symbol

• Welding symbols are used on dra"ings of parts andassemblies that are #oined together by "elding

• & complete "elding symbol contains all theinformation about a "elded #oint

•


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eference $ine, &rro"head, and (ail

• (he reference line is al"ays dra"n as a hori/ontalline

• (he arro" may be dra"n from either side of thereference line

• (he tail is used only "hen necessary to gi!eadditional information


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Weld Symbols

• Weld symbols may be part of the complete "eldingsymbol and indicate the type of "eld

*&merican Welding Society+


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&rro" Side and 0ther Side

• 0n the dra"ing of a "eld part, the arro" touchesthe line to be "elded

• (he side of the metal that the arro" touches iscalled the arro" side

• (he opposite surface is called the other side• (he arro" side information is al"ays sho"n belo"

the reference line


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oot 0pening and Gro!e &ngle

• (he root opening is the space bet"een the piecesat the bottom, or root, of the #oint

• Prior to "elding, the t"o pieces "ill be spaced apartthe distance indicated by the root opening

• (he root opening si/e appears inside the "eldsymbol


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Contour and inish Symbols

• (he shape of contour of the completed "eld bead issho"n in the "elding symbol

– Straight or cur!ed line –

Placed bet"een the "eld symbol and the finish symbol• f the "eld is not to remain in an >as "elded?

condition, a finish symbol is used


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$ength and Pitch of Weld

• ntermittent "elding – Short sections of the "eld are spaced across the #oint – =sed "hen full strength is not needed –

(he length dimension indicates the length of each "eld – (he pitch dimension indicates the distance from the

center of one "eld to the center of the next "eld


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• ntermittent fillet "elds may be re%uired on bothsides of a #oint

– With chain intermittent "elds, "elds begin and end at the

same spots – With staggered intermittent "elds, the "elds are offset – (his is sho"n on the "elding symbol by offsetting the fillet

"eld symbols


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• (his illustration sho"s a staggered "eld• :otice the staggered fillet symbols


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'ac4ing Welds and 9elt-(hrough Symbols

• Weld #oints that re%uire complete penetration maybe "elded from both sides

• & stringer bead or a co!er pass may be all that is

re%uired• n such cases, a bac4ing "eld symbol is used• (he melt-through symbol is used "hen 522@

penetration is re%uired on one-side "elds


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Weld-&ll-&round and ield Weld Symbols

• (he "eld-all-around symbol indicates that the sametype "eld #oint is to be used on all edges of a box orcylindrical part

• When "elds are to bemade a"ay from the shop,a field "eld symbol is used


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9ultiple eference $ines

• ("o or more reference lines may be used "hen ase%uence of operations is to be done

– (he reference line nearest the arro" indicates the first

operation – (he reference line furthest from the arro" indicates the

last operation


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Spot Welds

• & spot "eld is a method of #oining t"o or morepieces together "ith a "eld not at the edge of a part

• (he spot "eld symbol is a small circle• Pro#ection "elding is another process used to

produce spot "elds


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Spot Welds

• (he follo"ing information is gi!en for a spot "eld – Si/e – Strength –

Spacing – :umber of "elds – Welding process


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Seam Welds

• & seam "eld is another method of #oining t"o ormore pieces together

– $ap #oint –

'utt #oint• :o hole or slot is cut into any parts• (he si/e and strength of the "eld are sho"n to the

left of the "eld symbol


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e!ie" of Welding Symbols

• (his illustration sho"sexamples of !arioustypes of "elds in

!arious positions


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)lectrode &ngles

• ("o terms are used to describe the electrode angle,or position, in relation to the material being "elded

– (ra!el angle –

Wor4 angle


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(ra!el &ngle

• (he tra!el angle is measured from a lineperpendicular to the "eld axis in the plane definedby the "eld axis and electrode axis


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(ra!el &ngle

• 'ac4hand "elding – (he top of the electrodes

leads the "elding end of

the electrode – (he "elding arc ispointing bac4 to"ard the"eld bead

– (he tra!el angle is calleda drag angle or dragtra!el angle

• orehand "elding – (he "elding end of the

electrode points

for"ard in the directionof tra!el – (he tra!el angle is

called a push angle orpush tra!el angle


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Wor4 &ngle

• (he "or4 angle is measured from a lineperpendicular to the ma#or or nonbutting surface tothe plane containing the "eld axis and the

centerline of the electrode


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Commonly =sed &ngles

• or a butt "eld, the "or4 angle is usually /ero• or a fillet "eld, the "or4 angle is often 7A 3•

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