a. General. Overhead welding is performed from the underside of a joint.
b. Bead welds. In overhead welding, the metal deposited tends to drop or sag on the plate, causing the bead to have a high crown. To overcome this difficulty, the molten puddle should be kept small, and enough filler metal should be added to obtain good fusion with some reinforcement at the bead. If the puddle becomes too large, the flame should be removed for an instant to permit the weld metal to freeze. When welding light sheets, the puddle size can be controlled by applying the heat equally to the base metal and filler rod.
c. Butt Joints. The torch and welding rod position for welding overhead butt joints is shown in figure 11-15. The flame should be directed so as to melt both edges of the joint. Sufficient filler metal should be added to maintain an adequate puddle with enough reinforcement. The welding flame should support the molten metal and small welding puddle. To avoid burning through from one side, distribute it along the joint. Only a small puddle is required, so a rod should be used. Care should be taken to control the heat through the plates. This is particularly important when welding one side only.