Exercise 22-7 Making an Overhead Butt Weld 1. Obtain two pieces of carbon steel measuring 1/8″ × 1 1/2″ × 6″ (3.2 mm × 40 mm × 150 mm). 2. Clean one long edge on each piece. 3. Set up the welding equipment for welding carbon steel. Adjust the current and shielding gas flow rate for overhead welding. 4. Tack weld the two pieces together to form a butt joint with a root opening of 1/16″ (1.5 mm). Clamp the tack welded pieces in the overhead position. 5. Weld the butt joint. Use the correct torch and welding rod angles. Watch the weld pool. It must melt both pieces and form the keyhole shape. The weld must have complete penetration. Inspection: The completed weld should have even ripples. The edges of the weld should be the same width along the entire length. The root side of the weld should show consistent penetration. There should not be any porosity along the weld. Welding Other Metals Stainless steel and aluminum are metals very commonly welded with gas tungsten arc welding. You should develop proper skills for welding both. Chapter 21 discusses how welding these metals differs from welding carbon steel. After learning to weld carbon steel out of position, you should practice welding these metals in the horizontal, vertical, and overhead positions. Figures 20-10 through 20-13 list current and shielding gas settings for metals other than carbon steel. Each of the exercises in this chapter can be done with aluminum, stainless steel, or any other base metal weldable with GTAW. Chapter 22 GTAW: Horizontal, Vertical, and Overhead Welding Positions 331 Copyright Goodheart-Willcox Co., Inc.