Chapter 18Chapter 18

Welding Drawings

EngineeringDrawing and Design

EngineeringDrawing and DesignSeventh EditionSeventh Edition

18-1 Designing for welding

The primary importance of welding is to unite various pieces of metal so that they will operate as a unit structure to support the loads to be carriedWelding processes include arc welding, gas welding, and resistance welding (40 total processes exist)

Gas & Arc WeldingMost common form is oxyacetylene welding gets heat from the burning of flammable gases. It is slow compared to other modern welding methods so is used primarily for repair & maintenanceArc welding is the major industrial welding process-heat is generated by an electric arc struck between a welding electrode, or rod, and the workpiece. The arc is hot and melting and solidification of the weld metal occurs rapidly.

Resistance welding

Widely used especially for mass production workHeat is created from resistance losses as a high amperage current is sent across a joint between 2 mating surfaces

Plug welding

A plug weld refers to joining two pieces by welding through a hold in one of the pieces*

WELDING DRAWINGS

BASIC WELDING JOINTS

J-GROOVEFLARE BEVEL GROOVESPOTPROJECTIONSEAM

FILLETPLUGSLOTSQUARE GROOVEBEVEL GROOVE

APPLICABLE WELDSTYPE OF JOINT

WELDING DRAWINGS

BASIC WELDING JOINTS

J-GROOVEFLARE V-GROOVEFLARE BEVEL GROOVEEDGE FLANGE

SQUARE GROOVEV-GROOVEBEVEL GROOVEU-GROOVE

APPLICABLE WELDSTYPE OF JOINT

WELDING DRAWINGS

BASIC WELDING JOINTS

FLARE V-GROOVEFLARE BEVEL GROOVEEDGE FLANGECORNER FLANGESPOTPROJECTIONSEAM

FILLETSQUARE GROOVEV-GROOVEBEVEL GROOVEU-GROOVEJ-GROOVE

APPLICABLE WELDSTYPE OF JOINT

WELDING DRAWINGS

BASIC WELDING JOINTS

J-GROOVEFLARE BEVEL GROOVESPOTPROJECTIONSEAM

FILLETPLUGSLOTBEVEL GROOVE

APPLICABLE WELDSTYPE OF JOINT

WELDING DRAWINGS

BASIC WELDING JOINTS

EDGE FLANGECORNER FLANGESPOTPROJECTIONSEAMEDGE

PLUGSLOTSQUARE GROOVEBEVEL GROOVEV-GROOVEU-GROOVEJ-GROOVE

APPLICABLE WELDSTYPE OF JOINT

The difference between Weld symbol & Welding symbol…*

Weld symbol indicates the type of weld

Welding symbol is a method of representing the weld on drawings. It includes supplementary information & consists of the following 8 elements.

Reference line Arrow Basic weld symbol Dimension and

other data Supplementary

symbols Finish symbols Tail Specification,

process or other reference

18-2 Welding Symbols

Tail of the symbol designates the welding specification, procedures, or other information used to make the weld*Letters designate weld & cutting processes (Table 18-3)A-2, SAW, process specifications all can be found in the weld tail symbol*

Location significance of Arrow*

Arrow side- for fillet, groove, flanged weld symbols the arrow connecting the welding symbol reference line to one side of the jointOther side – the side opposite the arrow sideBoth sides

WELDING DRAWINGS

WELD TERMINOLOGY

Weld terminology

LegFaceThroatGroove radiusRoot opening (groove weld) is the space between the pieces before welding*Root faceGroove angle

WELDING DRAWINGS

WELD TERMINOLOGY

WELDING DRAWINGS

WELD TERMINOLOGY

WELDING DRAWINGS

WELDING SYMBOLS

WELDING DRAWINGS

WELD TERMINOLOGY

WELDING DRAWINGS

WELD TERMINOLOGY

WELDING DRAWINGS

FILLET AND GROOVE WELDS

SINGLE DOUBLE

FILLET

WELDING DRAWINGSWELDING DRAWINGS

FILLET AND GROOVE WELDS

SINGLE DOUBLE

SQUARE

WELDING DRAWINGS

FILLET AND GROOVE WELDS

SINGLE DOUBLE

BEVELGROOVE

WELDING DRAWINGS

FILLET AND GROOVE WELDS

SINGLE DOUBLE

V-GROOVE

WELDING DRAWINGS

FILLET AND GROOVE WELDS

SINGLE DOUBLE

J-GROOVE

WELDING DRAWINGS

FILLET AND GROOVE WELDS

SINGLE DOUBLE

U-GROOVE

WELDING DRAWINGS

FILLET AND GROOVE WELDS

SINGLE DOUBLE

FLARE- BEVEL

GROOVE

WELDING DRAWINGS

FILLET AND GROOVE WELDS

SINGLE DOUBLE

FLARE-V GROOVE

Orientation of specific weld symbols

Fillet, bevel-groove, J-groove, flare-groove, corner-flange welds symbols are drawn with the perpendicular leg always to the leftBreak in arrow-when only 1 member of a joint is to be prepared, the arrow has a break and points toward that member figure 18-9

Location of weld symbol wrt joint*

Welds on the arrow side of the joint are shown by placing the weld symbol below the reference lineWelds on the other side of the joint are shown by placing the weld symbol above the reference lineWelds on both sides of the joint are shown by placing the weld symbol on both sides of the reference line

Field welds & All around welds

Field welds*

Not made in the shop or at the place of initial constructionSmall black flag symbol* is placed above and at right angles to the reference lineFigure 18-10

All around weldsWeld extending completely around a joint is indicated by a weld-all-around symbol placed at the intersection of the reference line and the arrowFigure 18-11Not required for welds extending around the circumference of a pipe

More about weld symbols….

Combined weld symbols figure 18-12Contours obtained by welding

• Flat• Convex• Concave

Finishing of weldsgrinding(G)Chipping(C)Machining (M)Rolling (R)Hammering (H)

Last slide on weld symbols

Multiple reference lines indicate a sequence of operations to be done at a single location*

Tail of welding symbol* Welding process Tables 18-3,18-4 Omitted when no

references are required

WELDING DRAWINGS

COMBINED WELDING SYMBOLS

Design of welded joints

The size of the weld should always be designed with reference to the size of the thinner memberFillets welds are cheaper and easier to apply than groove

Full-strength fillet welds joining 2 different thicknesses of material should be sized using a table of recommended full strength weld sizes based on the thinner plate*

WELDING DRAWINGS

FINISHING OF WELDS

18-3 Fillet Welds & weld symbol (WS)

Dimensions of fillet welds are shown on the same side of the reference line as the WS & to the leftSpecify dimensions of fillet welds on both sides of a jointVertical part of fillet weld symbol always on left*

If using a general note giving fillet weld dimensions, dimensions may be left off WSIf dimensions differ from general note show them on WSLength of weld shown to right of WS

More on fillet welds…

Staggered intermittent fillet welds are designated in the weld symbol by staggering where the weld symbol appears on the reference line (p.652*)

Size of fillet welds

Table 8-5 p.651A practical method to size fillet welds is to design the weld for the thinner plate, making it sufficient to carry 1/3 to ½ the carrying capacity of the plate.

WELDING DRAWINGS

COMPARISON OF A CAST SHAFT SUPPORT WITH A WELDED STEEL SHAFT SUPPORT

18-4 Groove Weld symbolDimensions of groove weld are shown on the same side of the reference line as the welding symbolWhen both sides of a double-groove weld have the same (or different) dimension, both sides are dimensioned, however the root opening needs to appear only onceWhen a general note governs dimensions of groove welds, groove welds need not be dimensioned on the weld symbol

Back and Backing welds

Back or backing weld symbols are used to indicate bead-type back or backing welds of singe-groove weldsThe back weld is made after the groove weldThe backing weld is made before the groove weld

WELDING DRAWINGS

APPLICATION OF BACK AND BACKING WELD SYMBOLS

18-5 Other basic welds

PlugSlotSpotSeamSurfaceFlangedStud

WELDING DRAWINGS

OTHER BASIC WELDING SYMBOLS AND THEIR LOCATION SIGNIFICANCE