WELDING THEORY - OD1650 - LESSON 1/TASK 1
(2) Surface Contour of Back or Backing Welds. The contour symbols (figure 13, view C,
on the previous page) for back or backing welds (figure 12, view B, on page 27) are indicated in
the same manner as that for fillet welds.
(a) The melt-thru symbol will be used where at least 100 percent joint penetration of
the weld through the material is required in welds made from one side only (figure 13, view C).
(b) Melt-thru welds will be shown by placing the melt-thru weld symbol (figure 13,
view A) on the side of the reference line opposite the groove weld, flange, tee, or corner weld
symbol (figure 13, view C).
(c) Dimensions of melt-thru welds will not be shown on the welding symbol. If it is
desired to specify these dimensions they will be shown on the drawing.
(2) Surface Contour of Melt-Thru Welds. The contour symbols (refer to figure 3, view C,
on page 9) for melt-thru welds are indicated (figure 13, view D) in the same manner as that for
(a) The surfacing weld symbol (refer to figure 3, view A, on page 9) will be used to
indicate surfaces built up by welding (figure 14, view A, on the following page), whether built
up by single or multiple pass surfacing welds.
(b) The surfacing weld symbol does not indicate the welding of a joint, and hence has
no arrow or other side significance. This symbol will be drawn on the side of the reference line
toward the viewer and the arrow will point clearly to the surface on which the weld is to be