Welding symbols were developed to provide more information than simply indicating "weld here" on engineering drawings. There are various international standards for welding symbols, including AWS A2.4 in the US and ISO 2553 internationally. While similar, there are differences between standards that can cause confusion. It is important to understand which standard is being referenced when interpreting welding symbols.

1. Purpose Of Welding Symbol :
To indicate weld joint on engineering drawings were originally
devised by individual drawing offices to provide more useful
information than a simple arrow with the instruction ‘weld here’.
This symbol unsatisfactory, especially when drawings were passed
from one company to another and, to solve this problem, the
numerous symbols in existence were rationalized to some extent
countries compiling their own standard specifications for welding
symbols.
Weld Here
The information does not tell us much about the
wish of the designer

2. There are a number of standards throughout the world that relate to weld
symbols, but in the United States, AWS A2.4, Standard Symbols for
Welding, Brazing, and Non destructive Examination, is the standard.
In the global marketplace, the International Organization for
Standardization (ISO) has developed ISO 2553:1992, Welded, Brazed, and
Soldered Joints Symbolic Representation on Drawings .
The weld symbols (ISO 2553 : 1992) in this standard are very similar to
AWS A2.4, but there are differences that can cause interpretation
difficulties or the incorrect usage of welding symbols for the unacquainted
user.
In the ISO system, the dashed line can be drawn above or below the solid
line but the symbols on the solid line always refer to the arrow side of the
joint. It is recommended that the solid line is always drawn above the
dashed line as standard practice.

5. Welding Symbol
BS EN ISO 22553 AWS A2.4
Welding
Area
Welding
Area

6. Arrow line
Reference lines
Arrow side
Other side
BS EN 22553. Welding Symbols
(ISO 2553)
Arrow side
Other side

7. Other side
Arrow side
Both sides
BS EN 22553. Welding Symbols
(ISO 2553)

8. b
a
d
c
BS EN 22553. Welding Symbols
(ISO 2553)

9. Flat Convex
Concave
BS EN 22553. Welding Symbols
(ISO 2553)
Toes
shall be
blended

10. Field weld (site weld)
NDT
The component requires
NDT inspection
WPS
Additional information, the
reference document is
included in the box
Welding to be carried out all
round component
(peripheral weld)
BS EN 22553. Welding Symbols
(ISO 2553)

11. s = Deep of penetration
a = Design throat thickness
z = Leg length
a = 0.7 of z
a
z
BS EN 22553. Welding Symbols
(ISO 2553)
a 4
4mm throat
z 6
6mm leg
s

12. n = number of weld elements
l = length of each weld element
(e) = distance between each weld
element
Welds to be
staggered
Process
n x l (e)
2 x 10 (20)
3 x 10 (20)
111
BS EN 22553. Welding Symbols
(ISO 2553)

14. Single-V Butt flush cap Single-U Butt with sealing run
BS EN 22553. Welding Symbols (ISO 2553)
Single-V Butt with
permanent backing strip
M
Single-U Butt with
removable backing strip
M R

15. Single-bevel butt Double-bevel butt
Single-bevel butt Single-J butt
BS EN 22553. Welding Symbols (ISO 2553)

16. Partial penetration single-V butt
10
10
BS EN 22553. Welding Symbols (ISO 2553)

17. Ans to BS EN 22553 Fillet Welds ex: 1
1. Welded arrow side: A continuous fillet weld
with a 6 mm leg length , toes to be blended
smoothly.
2. Welded both sides: Three intermittent fillet
welds with 6 mm leg lengths, the length of each
weld 25 mm and the distance between each
weld 40 mm.
3. Welded arrow sides: Three intermittent fillet
welds with 10 mm leg lengths, the length of each
weld 40 mm, the distance between each weld
30mm.
Welded other side: Three intermittent fillet
welds 6 mm leg lengths, the length of each weld
50mm and the distance between each weld
25mm, welds to be staggered.
4. Welded arrow side: Three intermittent fillet
welds with 8 mm leg lengths, the length of each
weld 25 mm and the distance between each
weld 50 mm.
Welded other side: Two intermittent fillet welds
with 10 mm leg lengths, the length of each weld
20 mm and the distance between each weld
40mm, welds to be staggered.
3 x 25 (50)
2 x 20 (40)
10
8
50
50
25 25
40 40
20 20
25
6
40
50
40
50
50 25 25
30 30 40
30
10
6
3 x 40
3 x 50 (25)
(30)
3 x 25 (40)
3 x 25 (40)
6
6
25 40 25 40 25
25 25
25 40
40

18. Ans to BS EN 22553 Butt Welds ex: 1
1. Welded arrow side: Single ‘V’ butt weld with permanent
backing strip, flat weld profile.
M
2. Welded other side: Single “U” butt weld, flat weld profile
3. Welded arrow side: Single “V” butt weld depth of
preparation 10 mm
Welded other side: Backing run. (Plate thickness 15 mm.)
4. Welded arrow side: Single “J” butt weld, depth of
preparation 12 mm with a 8 mm fillet weld superimposed.
(plate thickness 15 mm.
Welded other side: 12 mm leg length fillet weld.
10
12
12
8

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