The advantages of symbols - Welding Symbols on Drawings - page 3

2 The advantages of symbols

When it is required to indicate a weld on a drawing, it may seem
that the weld can simply be drawn as it will appear. In the majority
of cases, symbolic representation can be used to cut down the time
needed to complete the drawing and improve clarity.
To save time in drawing the edge preparation for a butt/groove
weld or the shape and size of a fillet weld, a set of weld symbols
can be used. These symbols are placed on a horizontal reference line.
This line is attached to an arrow line which points to the location
of the weld (see Fig. 2.1 ). In the ISO system there are two parallel
reference lines, one solid and one dashed. In the AWS system a solid
reference line is used.

ISO AWS

Solid reference line Solid reference line

Tail Tail

Arrow line Arrow line

Dashed reference line

2.1 ISO and AWS reference lines and arrow lines.

Apart from weld symbols placed on the reference line, additional
information can be supplied adjacent to the tail which is generally
omitted when not required.
The arrow line can point in any direction as shown in Fig. 2.2 .
This is so that it can locate welds in any welding position, for
example flat or overhead. The arrow line is never drawn horizon-
tally because this would make it appear to be a continuation of the
reference line, which is always horizontal.

AWS ISO

ISO

ISO

AWS

AWS

2.2 Possible directions in which arrow lines may point.
It is conventional practice to refer to the opposite sides of a
welded joint as the arrow side and the other side (see Fig. 2.3 ).

Arrow side

Other side Arrow side

Other side

(a) (b)

2.3 The arrow side and other side of a T-joint (a) and a
butt/groove joint (b).