CHAPTER 25

WELDING REPRESENTATION

25.1IMPORTANCE OF THE DRAWING

• Welding is used very extensively and for large variety of purposes. It is essential to show accurate method of welding on working drawing.

• To provide complete weld information on the drawing, a system of welding symbols was developed by ANSI.

25.2 WELDING PROCESSES• Three welding processes

• Gas welding (Oxyacetylene welding)

• Electric arc welding (Arc welding)

• Electric resistance welding (Resistance welding)

25.3 TYPS OF WELD JOINTS• There are five basic types of weld joints.

• But joint

• Corner joint

• T joint

• Over lap joint

• Edge joint

25.4 TYPES OF WEELD• Four basic types of arc and Gas weld.

• Back or backing

• Fillet

• Plug or spot

• Groove

25.5 WELDING SYMBOLS

Note that for all fillet or groove symbols, the vertical side of the symbol is always drawn on the left.

A COMPLETE WELD SYMBOL

WELD PROCESS

• If no reference is indicated in the symbol, the tail is omitted.

Welds extending completely around a joint are indicated by an open circle around the elbow of the arrow.

FIELD WELD

Spot, seam, flash, or upset symbols usually do not have arrow side or other side significance and are simply centered on the reference line of the arrow.

BEVEL OR J-GROOVE WELD

FILLET WELD

C=chipping, G=grinding, M=machining, R=rollingH=hammering For only letter, no finishingFor finishing, show finish symbol as well.

25.7 GROOVE WELDThe depth of the V, J or U weld is the size.A general note may also be used as “ALL V-GROOVE WELDS TO HAVE 600ANGLE UNLESS OTHERWISE SHOWN”Root penetration and angle shown vertically.

When groove welds are to be approximately flush without finishing,

the flush contour symbol is added.

If the welds are to be machined, the flush contour symbol and standard finish symbol are shown.

25.8 BACK OR BACKING WELD

25.9 SURFACE WELDShow the deposit of the weld at left side of the symbol.Since used for build up the surfaces not for joint, no

arrow or other side, symbol always below.

25.10 PLUG OR SLOT WELDA hole or slot is made in one member to receive the weld. Size is the smallest diameter of the plug hole.Dimension for the slot weld on drawing as in (f).

Plug weld is to filled the full depth. If no then depth

is indicated inside symbol.

25.11 SPOT WELDThe size of the spot weld is its diameter. May have or may not have arrow side or other side significance.

25.12 SEAM WELDING May have or may not have arrow side or other side significance. The size of the seam weld is width.