Difference between ISO 2553 and AWS D1.1 welding symbols


Welding symbols: ISO 2553 or AWS D1.1? where is the difference?

Globally, there are two different standards on using welding symbols in drawings and other documentation as you can see in below picture. The first one is EN ISO 2553:2019, which is used mainly on the UK/ EU market. In this standard, when displaying a fillet weld of size ‘a’ [mm], the weld is situated on the same side as the arrow line. The weld symbol is positioned above the reference line. Dashed identification line is under the reference line.

Fillet weld symbol displayed by ISO 2553 & AWS D1.1 standards
Fillet weld symbol displayed by ISO 2553 & AWS D1.1 standards

The second standard is AWS A2.4 2020 Edition, which is used in the Pacific region, especially in the USA as well as also used worldwide in the middle east, Asia and Australia. In many ways, it is opposite to the EN ISO 2553. When displaying a fillet weld of size ‘a’ [inch], the weld is also situated on the same side as the arrow line. But the weld symbol is positioned below the reference line. There is no identification line used in AWS D1.1 like used in ISO 2553.

Also Check out:

  1. How to calculate the minimum and maximum size of a fillet weld.
  2. What are the minimum and maximum sizes of a Tack Weld?

Continue reading……

The most used standards are AWS, which stands for “American Welding Society” & ISO, which stands for “International Standards Organisation”.
The standards for usage of Welding Symbols in:
1. AWS system is “AWS A2.4: Standard Symbols for Welding, Brazing and Non-Destructive Examination”.
2. ISO system is “ISO 2553: Welding and Allied Processes – Symbolic Representations on Drawings”.

The major difference between these two systems are:

Welding symbols explained by chart and drawing 

1. ISO uses a dashed line, whereas AWS doesn’t use any dashed line.

2. The other side weld is represented on dotted line in ISO 2553 while there is no dashed line, hence weld symbol placed above the reference line in AWS welding symbol represents weld on other side.3

3. ISO 2553 uses throat size, a for fillet weld dimensions while AWS D1.1 uses Leg length, ‘z’ for fillet weld measurements.

There is a Single beveled groove and double fillet weld in the below picture. When using EN ISO standard, the beveled groove weld symbol is above the reference line and fillet weld below. When using AWS standard, the display is the opposite.

Single beveled groove and double fillet weld as per ISO 2553 and AWS D1.1
Single beveled groove and double fillet weld as per ISO 2553 and AWS D1.1

Watch this video on detailed training on Welding Symbols ​

Comparison between ISO 2553 vs. AWS D1.1 Welding Symbol

Single beveled groove and double fillet weld as per ISO 2553 and AWS D1.1
Single beveled groove and double fillet weld as per ISO 2553 and AWS D1.1

Recent Posts