Unit 16 Groove Welds 207 Surface Finish and Contour of Groove Welds The buildup of the groove weld above the sur- face of the base material is called reinforcement. Sometimes the welding symbol specifies that the reinforcement be minimized or removed. Groove welds to be made approximately flush (but not generally finished flush mechanically) are specified by a flush contour symbol. This symbol is placed above the weld symbol, as in Figure 16-17. Groove welds to be made flush by mechanical means are specified with a flush contour symbol and the method of making the weld flush, Figure 16-18. Groove welds to be finished mechanically with a con- vex contour are specified by a convex contour sym- bol. The method of finishing the weld to a convex contour is also given, Figure 16-19. Melt-Through, Back, and Backing Welds The melt-through, back, and backing weld sym- bols show that a melt-through to the other side, bead- type back, or backing weld is needed with a single- groove weld. Points to remember include: ❍ A back weld is made after the groove weld. ❍ A backing weld is made before the groove weld. ❍ A melt-through is a visible reinforcement produced in a groove weld from one side. A note states whether a back or backing weld is to be made. This note is placed in the tail of the weld- ing symbol, Figure 16-20. As shown, a back or back- ing weld symbol is located on the side of the refer- ence line that is opposite the groove weld symbol. A flush contour symbol, added to the back or backing weld symbol, indicates the weld should be approximately flush with the base metal, Figure 16-21. If the back or backing weld is to be made flush by mechanical means, the method of making the weld flush is added to the flush contour symbol, Figure 16-22. When a back or backing weld is to be finished to a convex contour by mechanical means, a convex contour symbol and finish symbol are added to the weld symbol. Figure 16-17. A flush contour symbol is placed above the weld symbol when the groove weld is to be made approximately flush and without the use of grinding, chipping, hammering, or machining. Desired weld Symbol Weld deposited flush with base metal Figure 16-18. Groove welds to be made flush mechanically are specified by a flush contour symbol and by the method to use to make the weld flush. Weld made flush with base metal by grinding Desired weld Symbol G Figure 16-19. When groove welds are to be finished mechanically to a flush contour, they are specified by a convex contour symbol and the method of finishing. Finished to smooth convex contour by machining Desired weld Symbol M M Figure 16-16. Groove radii and root faces of U- and J-groove welds are shown by cross section, detail, or other means with a welding symbol reference. 1 16 3 16 TO 3 16 MAX. X R 1 4 MIN ANGLE X 45° MIN 20° MIN 12° MIN POSITION ALL F, V, O F DETAIL E (EXCEPT FROM DWG B2345, "GROOVE WELD STANDARDS") Symbol SEE DWG B2345 DETAIL E