The following notes are meant as a guide to the method
of applying the more commonly used welding symbols
relating to the simpler types of welded joints on
engineering drawings. Where complex joints involve
multiple welds it is often easier to detail such constructions
on separate drawing sheets.
Each type of weld is characterized by a symbol
given in Table 26.1 Note that the symbol is representative
of the shape of the weld, or the edge preparation, but
does not indicate any particular welding process and
does not specify either the number of runs to be deposited
or whether or not a root gap or backing material is
to be used. These details would be provided on a welding
procedure schedule for the particular job.
It may be necessary to specify the shape of the weld
surface on the drawing as flat, convex or concave and
a supplementary symbol, shown in Table 26.2, is then
added to the elementary symbol. An example of each
type of weld surface application is given in Table 26.3.
A joint may also be made with one type of weld on
a particular surface and another type of weld on the
back and in this case elementary symbols representing
each type of weld used are added together. The last
example in Table 26.3 shows a single-V butt weld
with a backing run where both surfaces are required to
have a flat finish.
A welding symbol is applied to a drawing by using
a reference line and an arrow line as shown in Fig.
26.1. The reference line should be drawn parallel to
the bottom edge of the drawing sheet and the arrow
line forms an angle with the reference line. The side of
the joint nearer the arrow head is known as the ‘arrow
side’ and the remote side as the ‘other side’.
The welding symbol should be positioned on the
reference line as indicated in Table 26.4.
Sketch (a) shows the symbol for a single-V butt
weld below the reference line because the external
surface of the weld is on the arrow side of the joint.
Sketch (b) shows the same symbol above the
reference line because the external surface of the weld
is on the other side of the joint.
Manual of
Engineering Drawing
Second edition
Colin H Simmons
I.Eng, FIED, Mem ASME.
Engineering Standards Consultant
Member of BS. & ISO Committees dealing with
Technical Product Documentation specifications
Formerly Standards Engineer, Lucas CAV.
Dennis E Maguire
CEng. MIMechE, Mem ASME, R.Eng.Des, MIED
Design Consultant
Formerly Senior Lecturer, Mechanical and
Production Engineering Department, Southall College
of Technology
City & Guilds International Chief Examiner in
Engineering Drawing
Elsevier Newnes
Linacre House, Jordan Hill, Oxford OX2 8DP
200 Wheeler Road, Burlington MA 01803
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