Copyright Goodheart-Willcox Co., Inc. 142 Gas Tungsten Arc Welding Handbook Procedure: 1. Prepare and clean the materials. 2. Tack weld the plates with 3/32″ (2.4 mm) or 1/8″ (3.2 mm) spacing, depending on the filler metal used. Mount the joint in the horizontal position. 3. Weld the root pass with 3/32″ (2.4 mm) or 1/8″ (3.2 mm) diameter welding rod. A. Add the welding rod to the upper part of the weld pool. Use the work and travel angles shown in Figure 8-15. 4. Wire brush the weld to remove the oxide film (both passes). 5. Realign the torch and weld a second pass. Use a 3/32″ (2.4 mm) or 1/8″ (3.2 mm) diameter welding rod. A. Do not oscillate the torch. The weld should be approximately 1/16″ (1.6 mm) wider than the groove, and the weld crown should not be over 1/16″ (1.6 mm) high. Problem Areas and Corrections: 1. Undercut. Possible cause: Sagging due to gravity. Solution: Add welding rod at the top of the weld pool. Possible cause: Weld bead is excessively large. Solution: Hold the torch and welding rod at the proper angles. Solution: Do not oscillate the torch. Keep the weld pool small. Possible cause: Excessive amperage. Solution: Use a lower amperage range and add filler metal more often. Possible cause: Heat buildup in the weld pool. Solution: Allow the plates to cool between passes. 2. Uneven bead width. Possible cause: Variation in the size and shape of the weld pool. Solution: Determine the size of each pass before starting. Solution: Determine the location of each pass before starting. Solution: Maintain the same pass dimensions for the full length of the joint. Welding Procedure Number 8-8 Weld joint type: Square-groove butt Position: Vertical uphill Material type: Cold-rolled steel Thickness: 11 gauge Filler metal: ER70S-6 Diameter: 3/32″ (2.4 mm) or 1/8″ (3.2 mm) (welder’s preference) Machine setup: DCEN high-frequency start Shielding gas: Argon CFH: 15–25 Tungsten type: 1%, 1.5%, or 2% lanthanated, ceriated, or thoriated Diameter: 3/32″ (2.4 mm) (tapered) Procedure: 1. Prepare and clean the materials. 2. Tack weld the plates with 3/32″ (2.4 mm) or 1/8″ (3.2 mm) spacing depending on the filler metal used. Mount the joint in the vertical position. 3. Weld the root pass with 3/32″ (2.4 mm) or 1/8″ (3.2 mm) diameter welding rod. Use the same travel and work angles shown in Figure 8-16. A. Add the welding rod to the top of the weld pool. B. Add the welding rod directly on the pool centerline. C. Keep the electrode centered over the molten pool. 4. Wire brush the weld to remove the oxide film (all passes). 5. Realign the torch and weld the second pass using a 3/32″ (2.4 mm) or 1/8″ (3.2 mm) diameter welding rod. A. Use a slight oscillation for a wider bead. B. Add welding rod at the edge of the weld pool and always wait for a moment before dipping the filler into the weld pool. Keep the weld pool in a fluid state. Problem Areas and Corrections: 1. Undercut. Possible cause: Sagging due to gravity. Solution: Add welding rod at the top of the weld pool. Possible cause: Weld bead is excessively large. Solution: Hold the torch and welding rod at the proper angles. Solution: Do not oscillate the torch. Keep the weld pool small. Possible cause: Excessive amperage. Solution: Use a lower amperage range and add filler metal more often.