Objectives
1.
2.
3.
4.
5.
Know the name of the AWS & ISO
standards for welding symbols
List the eight elements that may be found
on a welding symbol
List the basic weld symbols
List the supplementary symbols
Identify the applications of the different
weld symbols
Weld symbols on drawings
A method of transferring information from the
design office to the workshop is:
Please weld
here
The above information does not tell us much about the wishes
of the designer. We obviously need some sort of code which
would be understood by everyone.
Most countries have their own standards for symbols.
Some of them are AWS A2.4 & BS EN 22553 (ISO 2553)
AWS Standard

Weld symbol
 Graphic symbol that indicates weld required

Welding symbol
 Following eight elements:
 Reference line (required)
 Arrow (required)
 Basic weld symbols
 Dimensions and other data
 Supplementary symbols
 Finish symbols
 Tail
 Other specifications
Welding Symbol Components
Welding Symbol Components
Welding Symbol Components
Weld symbols on drawings
Advantages of symbolic representation:

simple and quick plotting on the drawing

does not over-burden the drawing

no need for additional view

gives all necessary indications regarding the specific joint to
be obtained
Disadvantages of symbolic representation:

used only for usual joints

requires training for properly understanding of symbols
Dimensions
Convention of dimensions
In most standards the cross sectional dimensions are given to
the left side of the symbol, and all linear dimensions are give on
the right side
BS EN ISO 22553
a = Design throat thickness
s = Depth of Penetration, Throat thickness
z = Leg length (min material thickness)
AWS A2.4
•In a fillet weld, the size of the weld is the leg length
•In a butt weld, the size of the weld is based on the depth of the
joint preparation
Weld symbols on drawings
Joints in drawings may be indicated:
•by detailed sketches, showing every dimension
•by symbolic representation
Elementary Weld Symbols
Square Groove Weld
Single V Groove Weld
Elementary Weld Symbols
Single Bevel Groove Weld
Single V Groove Weld with Broad Root Face
Elementary Weld Symbols
Single Bevel Groove Weld with Broad Root Face
Single U Groove Weld
Elementary Weld Symbols
Single J Groove Weld
Backing Weld
Elementary Weld Symbols
Fillet Weld
Plug / Slot Weld
Elementary Weld Symbols
Spot Weld
Seam Weld
Elementary Weld Symbols
Edge Weld
Surfacing
SUPPLEMENTARY SYMBOLS
Weld Profile
Flat
Convex
Concave
SUPPLEMENTARY SYMBOLS
Toes blended
smoothly
M
MR
Permanent
Backing Strip
Removable
Backing Strip
SUPPLEMENTARY SYMBOLS
Peripheral Welds
Basic Weld Symbols
AWS
Basic Weld Symbols
AWS
Welding Symbols
AWS
ISO 2553 / BS EN 22553
24 of 691
Plug weld
Square Butt weld
Resistance spot weld
Steep flanked
Single-V Butt
Resistance seam weld
Surfacing
ISO & AWS
Arrow Line
(BS EN ISO 22553 & AWS A2.4):
Convention of the arrow line:
•
Shall touch the joint intersection
•
Shall not be parallel to the drawing
•
Shall point towards a single plate preparation (when only
one plate has preparation)
Reference Line
(AWS A2.4)
Convention of the reference line:
Shall touch the arrow line
Shall be parallel to the bottom of the drawing
Reference Line
(BS EN ISO 22553)
Convention of the reference line:
•
Shall touch the arrow line
•
Shall be parallel to the bottom of the drawing
•
There shall be a further broken identification line above or
beneath the reference line (Not necessary where the weld
is symmetrical!)
or
Double side weld symbols
(BS EN ISO 22553 & AWS A2.4)
Convention of the double side weld symbols:
Representation of welds done from both sides of the joint
intersection, touched by the arrow head
Fillet weld
Double bevel
Double V
Double U
Double J
ISO 2553 / BS EN 22553
MR
30 of 691
M
Single-V Butt with
permanent backing strip
Single-V Butt flush cap
Single-U Butt with
removable backing strip
Single-U Butt with sealing run
ISO 2553 / BS EN 22553
31 of 691
Single-bevel butt
Double-bevel butt
Single-bevel butt
Single-J butt
ISO 2553 / BS EN 22553
s10
10
15
Partial penetration single-V butt
‘S’ indicates the depth of penetration
ISO 2553 / BS EN 22553
a = Design throat thickness
s = Depth of Penetration, Throat
thickness
z = Leg length(min material thickness)
a = (0.7 x z)
33 of 691
z
z6
6mm leg
a4
a
s
4mm Design throat
s6
6mm Actual throat
ISO 2553 / BS EN 22553
34 of 691
Arrow side
Arrow side
ISO 2553 / BS EN 22553
35 of 691
s6
6mm fillet weld
Other side
s6
Other side
ISO 2553 / BS EN 22553
36 of 691
n = number of weld elements
l = length of each weld element
(e) = distance between each weld element
n x l (e)
Welds to be
staggered
2 x 40 (50)
3 x 40 (50)
111
Process
ISO 2553 / BS EN 22553
All dimensions in mm
5
80
80
z5
3 x 80 (90)
z6
3 x 80 (90)
80
5
6
6
90
90
90
ISO 2553 / BS EN 22553
All dimensions in mm
6
z8
3 x 80 (90)
z6
3 x 80 (90)
80
80
80
90
90
90
6
8
8
Supplementary symbols
(BS EN ISO 22553 & AWS A2.4)
Convention of supplementary symbols
Supplementary information such as welding process, weld
profile, NDT and any special instructions
Site Weld
Toes to be ground smoothly
(BS EN only)
Concave or Convex
Weld all round
Supplementary symbols
(BS EN ISO 22553 & AWS A2.4)
Convention of supplementary symbols
Supplementary information such as welding process, weld profile,
NDT and any special instructions
Ground flush
MR
M
Removable
backing strip
Permanent
backing strip
111
Welding process
numerical BS EN
Further supplementary information, such as WPS number, or
NDT may be placed in the fish tail
ISO 2553 / BS EN 22553
41 of 691
a
b
c
d
ISO 2553 / BS EN 22553
Mitre
Concave
Convex
Toes
shall be
blended
ISO 2553 / BS EN 22553
Complimentary Symbols
Field weld (site weld)
Welding to be carried out
all round component
(peripheral weld)
NDT
WPS
The component requires
NDT inspection
Additional information,
the reference document
is included in the box
ISO 2553 / BS EN 22553
44 of 691
Numerical Values for Welding Processes:
111:
MMA welding with covered electrode
121:
Sub-arc welding with wire electrode
131:
MIG welding with inert gas shield
135:
MAG welding with non-inert gas shield
136:
Flux core arc welding
141:
TIG welding
311:
Oxy-acetylene welding
72:
Electro-slag welding
15:
Plasma arc welding
AWS A2.4 Welding Symbols
AWS Welding Symbols
Root Opening
Depth of Bevel
1 (1-1/8)
Effective Throat
1/8
60o
Groove Angle
AWS Welding Symbols
Welding Process
GSFCAW
1 (1-1/8)
GMAW
GTAW
SAW
1/8
60o
AWS Welding Symbols
Welds to be
staggered
3 – 10
3 – 10
SMAW
Process
3
10
3
AWS Welding Symbols
3rd Operation
Sequence of
Operations
2nd Operation
1st Operation
1 (1-1/8)
1/8
60o
FCAW
AWS Welding Symbols
RT
Sequence of
Operations
MT
MT
1 (1-1/8)
FCAW
1/8
60o
Fillet Welds and Symbol
Fillet weld triangular-shaped weld placed on the
joint
 Fillet weld symbol triangular in shape

 Vertical line of fillet weld symbol always drawn to left
of symbol
 Size always shown to left of symbol and length to right
of symbol
 No length given, then weld should run full length of
joint
AWS Welding Symbols
52 of 691
Dimensions- Leg Length
6 leg on member A
6/8
Member A
6
8
Member B
AWS A 2.4 rules-example
10
3 x 50 (70)
70
50
10
Fillet welds
Fillet weld dimensions according AWS A 2.4
8
8
5x8
5
8
5 leg on
vertical
member
Intermittent fillet welds
Chain intermittent fillet weld
pitch (e)
length (l)
z
z
Symbol to AWS A2.4
z
l-e
l-e
Intermittent fillet welds
Staggered intermittent fillet weld
pitch (e)
e/2
length (l)
z
z
z
Symbol to AWS A2.4
l-e
l-e
Examples:
Fillet Welds on T-Joints
Example: Fillet Weld Length and
Pitch Indications
Weld-All-Around Symbol
Used when weld is to extend all way around joint
or series of connected joints
 Symbol: circle viewable at junction of reference
line and arrow

Groove Welds

Seven types of groove welds and symbols to
represent them
 Square
V
 Bevel
U
J
 Flare-V
 Flare-bevel
Symbols take the shape
of the groove the weld
is to be placed in.
Groove Welds
Place in a joint
 Used to make butt joints, but can be used to
make other types of joints
 Double bevel

 One of joint members has bevel on both sides and joint
is to be welded from both sides
 V shape
V-groove Weld on Butt Joint
Double V-groove Weld on Butt Joint
Contour Symbol and Letters Which
Indicate Finishing Method