Weld Symbols on a Drawing – Refresh Your
Knowledge ANSI/AWS A2.479
The eight elements which may appear in a welding symbol are:
reference line, arrow, basic weld symbols, dimensions and other data,
supplementary symbols, finish symbols, tail and specification and
process or other reference. Let us discuss the one by one.
Reference Line: This is the basis of the welding symbol. All other
elements are oriented with respect to this line. The arrow is affixed to one
end and a tail, when necessary, is affixed to the other.
Arrow: This connects the reference line to one side of the joint in the case
of groove, fillet, flange, and flash or upset welding symbols. This side of
the joint is known as the arrow side of the joint. The opposite side is
known as the other side of the joint. In the case of plug, slot, projection,
and seam welding symbols, the arrow connects the reference line to the
outer surface of one of the members of the joint at the center line of the
weld. In this case the member to which the arrow points is the arrow side
member: the other member is the other side member. In the case of bevel
and Jgroove weld symbols, a twodirectional arrow pointing toward a
member indicates that the member is to be chamfered.
Basic Weld Symbols: These designate the type of welding to be
performed. The basic symbols which are shown in the table Basic Weld
Symbols are placed approximately in the center of the reference line,
either above or below it or on both sides of it as shown in above figure.
Welds on the arrow side of the joint are shown by placing the weld
symbols on the side of the reference line towards the reader (lower side).
Welds on the other side of the joint are shown by placing the weld
symbols on the side of the reference line away from the reader
Supplementary Symbols: These convey additional information relative to
the extent of the welding, where the welding is to be performed, and the
contour of the weld bead. The “weldallaround” and “field” symbols are
placed at the end of the reference line at the base of the arrow as shown
in first figure and the table Supplementary Weld Symbols.
Dimensions: These include the size, length, spacing, etc., of the weld or
welds. The size of the weld is given to the left of the basic weld symbol
and the length to the right. If the length is followed by a dash and another
number, this number indicates the centertocenter spacing of intermittent
welds. Other pertinent information such as groove angles, included angle
of countersink for plug welds and the designation of the number of spot or
projection welds are also located above or below the weld symbol. The
number designating the number of spot or projection welds is always
enclosed in parentheses.
Contour and Finish Symbols: The contour symbol is placed above or
below the weld symbol. The finish symbol always appears above or below
the contour symbol. The following finish symbols indicate the method, not
the degrees of finish: C—chipping; G—grinding; M—machining; R—
rolling; and H—hammering.
Tail: The tail which appears on the end of the reference line opposite to
the arrow end is used when a specification, process, or other reference is
made in the welding symbol. When no specification, process, or other
reference is used with a welding symbol, the tail may be omitted.