Handbook-Preparations For Welding

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Flange Welds. A simple way of making a variant of the butt weld in sheet steel is to roll up, or flange, the edges of

the pieces to be joined, as shown in Fig. 12-2. The thinner the sheet, the easier it is to flange the edges, and the

more useful this design becomes. Using this joint design, a skilled operator can make good welds in sheet thinner

than 20-gauge. Further, the rolled edges, which are melted during the welding, eliminate the need for using filler

metal. The height of the flange should normally be about the same as the thickness of the sheet, or slightly greater.

Lap Welds. The lap weld, single or double (as illustrated in Fig. 12-3), is not recommended for oxy-acetylene

welding. The single lap weld is not a strong weld. While the double lap weld has more strength, it is certainly no

better than a single butt weld, properly made, and requires twice the time and twice the filler metal needed for the

butt weld. The double lap weld is sometimes used in arc welding sheet with covered electrodes because of the

difficulty of making good butt welds in thin sheet with that process.

Single-V Butt Welds. To weld steel plate in thicknesses above 3/16-in. (0.5 cm), and up to about 1/2-in. (1.2 cm),

the single-V butt weld, shown in Fig. 12-4, is used both in oxy-acetylene welding and in most electric welding

processes. The plate edges are beveled to form an included angle of between 50 and 90 degrees. Filler metal is

always required. The beveled edges should normally be squared off a bit at the bottom to produce a ”nose”, as

shown,

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Fig. 12-2. The flange weld for sheet metal. When it is possible to flange the

metal, this is the ideal way to make full-strength welds in thin sheet. (See Fig.

12-7 for a jig which can be used with this design.)