Chapter 3 Welding Joints, Positions, and Symbols 51 than one weld pass is required to make a strong joint with complete penetration. See Figure 3-9B. The fi rst weld pass is the root pass. The second or intermediate weld pass is called a fi ller pass. The fi nal weld pass is the cover pass. See Figure 3-10A. On very thick metal (over 1/2″ or 13mm), multiple fi ller passes are required to fi ll deep and wide joints, Figure 3-10B. Generally, a weld bead should not be thicker than 1/4″ (6.4mm). A weld bead may be made as a stringer bead or a weave bead. 3.2.2 Stringer Bead A stringer bead is used when a standard bead width is acceptable. Stringer beads are made by moving the torch or electrode along the weld without any side-to-side motion. See Figure 3-11A. Multiple stringer beads need to be made to fi ll a V-groove butt weld on very thick metal as shown in Figure 3-10B. 3.2.3 Weave Bead A weave bead is used to create a wider weld pool. A weave bead is formed by moving the torch or elec- trode from side-to-side as the weld pass progresses along the weld joint. See Figure 3-11B. Various torch or electrode movement patterns can be used when making a weave bead. The crescent motion, shown in Figure 3-11C, is one of the most popular patterns. 3.3 Joint Geometry The American Welding Society defi nes joint geometry as “the shape and dimensions of a (weld) joint, in cross section, prior to welding.” Joint geom- etry is generally determined by a welding engineer or designer. The assembly design and the dimensions of a joint depend on the metal thickness and shape and on the load requirements of the parts. The parts are prepared to ensure that the weld will have adequate penetration. The joint geometry design also provides space for the welder to reach near the bottom of the weld joint with the torch or electrode. Figure 3-10. Multiple-pass welds. A—Three weld passes are used in this example. The fi rst two passes are stringer beads. The cover pass is a weave bead. B—Twenty stringer beads were used in this weld on very thick metal. Each bead is no thicker than 1/4″ (6.4mm). Weld pool Torch tip Cover pass (3rd bead) Direction of travel Filler pass (2nd pass) Root pass (1st bead) A B Figure 3-11. Comparison of stringer and weave beads. A—A stringer bead is in progress on a square-groove butt joint. The bead width is two to three times the metal thickness. B—A weave bead is in progress. The torch tip and weld pool are moved from side-to-side in the direction of the arrow. C—A suggested motion for creating a weave bead. The bead width is seldom greater than 3/4″–1″ (19mm–25mm). A B C Direction of travel Weld pool Torch tip Direction of motion