The application of welding symbols to working drawings

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

Read more........