Chapter 3 Welding Joints, Positions, and Symbols 63 symbol by offsetting the fi llet weld symbols. See Figure 3-32, views C and D. Continuous and intermittent welds may be made on the same joint. In such a case, the drawing will use dimensions to show where each weld symbol’s effec- tiveness begins and ends. See Figure 3-33, view A. A spacing different from the regular pitch is used between the end of the continuous weld and the beginning of the intermittent weld. See the 4″ dimen- sion in Figure 3-33, view B. This spacing is equal to the intermittent pitch minus the length of one inter- mittent weld. The spacing between the continuous and intermittent welds in Figure 3-33, view B, equals the pitch minus the length, or 6″–2″ = 4″, as shown. 3.5.8 Backing Welds and Melt- Through Symbols Weld joints that require complete penetration may be welded from both sides. A stringer bead (single pass weld without a weaving motion) or a cover pass (single pass using a weaving motion) may be all that is required on the side opposite a groove weld to ensure complete penetration. In such cases, a backing weld symbol is used, Figure 3-34A. The melt-through symbol is used when 100% penetration is required on one-side welds, Figure 3-34C. 3.5.9 Weld-All-Around and Field Weld Symbols Directions given on a welding symbol are no longer of any value when the weld joint makes a sharp change in direction, such as going around a corner. When the joint changes direction sharply, either a new welding symbol or a weld-all-around symbol may be used. The weld-all-around symbol indicates that the same type weld joint is to be used on all edges of a box or cylindrical part. See Figure 3-35. Some parts are assembled and welded in the shop. It is often necessary to take parts to the job site or into the fi eld to make fi nal assemblies and welds. When Figure 3-33. Continuous and intermittent welds. Note that the dimensions on the top welding drawing limits use of the welding symbol to the distance shown. Note also that the spacing between continuous and intermittent welds is equal to the pitch minus the length of one intermittent weld (4″ in this application). 16″ 12″ 12″ 1/4 1/4 2-6 1/4 A B 6″ 12″ 4″ 2″ 4″ 2″ 4″ 12″ 45 1/16 Size Backing weld symbol Melt-through symbol Complete penetration or melt-through Backing weld 1/16″ A B C D Figure 3-34. Backing weld and melt-through symbols. A backing weld may be used to obtain 100% penetration when welding is possible on both sides, as shown in A and B. The melt-through symbol is used on welds that are welded from one side only and require 100% penetration, as shown in C and D.