Hard- Surfacing, Building Fusion Welding Carbon Welding Non-Ferrous Metals Heating & Heat Treating Braze Welding Welding Cast Iron Welding Ferrous Metals Brazing & Soldering Equipment Set-Up Operation Equipment For OXY-Acet Structure of Steel Mechanical Properties of Metals Oxygen & Acetylene OXY-Acet Flame Physical Properties of Metals How Steels Are Classified Expansion & Contraction Prep For Welding OXY-Acet Welding & Cutting Safety Practices Manual Cutting Oxygen Cutting By Machine Appendices Testing & Inspecting
1 PREPARATION FOR WELDING In the broadest sense, ”preparation for welding” would include the design of a structure – deciding where the welds should be placed, what type of joint design should be used for each weldment, and what sequence should be
followed in making the welds. However, full treatment of structural design for welding is beyond the scope of this
book; moreover, oxy-acetylene welding is seldom used for all the welds in a structure, other than by the hobbyist or
home craftsman. This chapter will thus be limited to describing different configurations of welded joints, methods
for shaping and cleaning the edges of the parts to be welded, and ways in which the parts to be joined can be
preheated, when such preheating is required.
Joint Configurations Square Butt Welds. The simplest of all joint designs is the square butt weld, in which pieces with squared edges are merely brought quite close together, as illustrated in Fig. 12-1. In the oxy-acetylene welding of steel, the square
butt weld can be used with material as thin as about 20-gauge (0.04 in. or 1 mm) sheet to as thick as 3/16-in. (5
mm) plate. (By trade practice, rolled metal in thicknesses up to 1/8-in. is termed ”sheet”; in thicknesses above 1/8-
in. it is termed ”plate”.) Filler metal, in the form of welding rod, is almost always used in making square butt welds.
It is seldom possible to make a satisfactory, full-strength weld by merely butting the pieces tight together, without
spacing, and then melting the edges together.
Fig. 12-1. Square butt weld specifications for sheet steel or thin plate. Thicknesses up to 11 gauge (1/8”) Spacing 1/16” to 3/32” 3/32” to 1/8” 1/8” to 3/16”