Copyright Goodheart-Willcox Co., Inc. 144 Gas Tungsten Arc Welding Handbook C. Wire brush the weld to remove the oxide film (all passes). D. Weld the second pass. Make sure the weld pool fuses into the bottom plate and overlaps the root pass by approximately 50%. See Figure 8-18. E. Weld the third pass. Make sure the weld pool fuses into the top plate and the second pass, creating a flat weld in the joint. Problem Areas and Corrections: 1. Concave weld crown or improper contour. Possible cause: Insufficient filler metal. Solution: Add welding rod more often. Possible cause: Incorrect torch angle and improperly placed welds. 2. Leg sizes are not equal. Possible cause: Incorrect torch angle. Solution: Reposition the torch to keep the weld pool even. Possible cause: Too much filler metal. Weld pool is too heavy. Solution: Add less filler metal. 3. Undercut on top weld. Possible cause: Weld pool is too hot. Solution: Add welding rod more often. Possible cause: Incorrect torch angle. Solution: Reposition the torch to keep the weld pool even. Welding Procedure Number 8-11 Weld joint type: T-joint Position: Vertical uphill Material type: Cold-rolled steel Thickness: 11 gauge Filler metal: ER70S-2 or 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. Align the plates. 3. Tack weld the two plates at approximately right angles. 4. Weld the joint using the torch and welding rod angles shown in Figure 8-19. A. Add the filler metal in small amounts. B. Feed the welding rod directly into the intersection of the joint. C. Wire brush the joint to remove the oxide film. 3rd pass 1st pass (root) 2nd pass Figure 8-18. The three passes used to weld a T-joint in the horizontal position. (Mark Prosser) Figure 8-19. Torch and welding rod positions for uphill welding a T-joint in the vertical position. (Mark Prosser)