ISO 4063 is the international standard that defines a numerical classification system for welding, brazing, soldering, and allied processes. It assigns standard process numbers so that welding methods are described consistently across drawings, procedures, qualifications, and contracts.
ISO 4063 is a technical classification standard, widely used in fabrication, manufacturing, construction, and engineering documentation.
What is ISO 4063?
ISO 4063 is published by the International Organization for Standardization. Its purpose is to provide a common, unambiguous language for identifying joining processes, regardless of local terminology or trade names.
For example, processes commonly known as MIG, MAG, TIG, or MMA are referenced using standard ISO 4063 process numbers.
What does ISO 4063 cover?
ISO 4063 classifies:
- Welding processes
- Brazing and soldering processes
- Thermal cutting and allied processes
- Variants and sub-processes
Each process is identified by a two- or three-digit number, which can be extended to show specific variants.
Why ISO 4063 is important
Using ISO 4063 helps organisations:
- Avoid confusion caused by local or informal process names
- Standardise welding documentation internationally
- Ensure consistency between design, fabrication, and inspection
- Support compliance with welding qualification standards
- Improve clarity in contracts and specifications
It is especially important in multinational projects and regulated industries.
Structure of ISO 4063 process numbers
ISO 4063 uses a hierarchical numbering system:
- Main process group – first digit(s)
- Process subgroup – additional digits
- Specific variant – further digits if required
This allows general processes to be described at a high level or in precise detail.
Main welding process groups (examples)
Some of the most commonly used ISO 4063 process groups include:
1 – Arc welding
Includes processes such as:
- 111 – Manual metal arc welding (MMA / stick welding)
- 131 – Metal inert gas welding (MIG)
- 135 – Metal active gas welding (MAG)
- 141 – Tungsten inert gas welding (TIG)
2 – Resistance welding
Includes processes such as:
- 21 – Resistance spot welding
- 22 – Resistance seam welding
3 – Gas welding
Includes oxy-fuel welding processes.
4 – Other welding processes
Includes processes such as:
- 41 – Electron beam welding
- 42 – Laser beam welding
8 – Brazing and soldering
Includes:
- 83 – Brazing
- 84 – Soldering
ISO 4063 in welding documentation
ISO 4063 process numbers are commonly used in:
- Welding procedure specifications (WPS)
- Procedure qualification records (PQR / WPQR)
- Welder qualification records
- Technical drawings and fabrication notes
- Inspection and quality documentation
For example, a WPS may specify Process 141 instead of “TIG welding”.
ISO 4063 vs trade names
| Trade or common name | ISO 4063 process |
|---|---|
| Stick welding | 111 |
| MIG welding | 131 |
| MAG welding | 135 |
| TIG welding | 141 |
| Laser welding | 42 |
ISO 4063 avoids ambiguity by focusing on process fundamentals, not branding.
Who is ISO 4063 for?
ISO 4063 is used by:
- Welding and fabrication engineers
- Welding coordinators and inspectors
- Quality and compliance teams
- CAD designers and draughtspersons
- Fabrication workshops and manufacturers
It is essential wherever welding processes must be clearly defined and controlled.
Is ISO 4063 certifiable?
No. ISO 4063 cannot be certified.
It is a classification and reference standard. Organisations are not certified to ISO 4063, but welding procedures and qualifications routinely reference ISO 4063 process numbers.
Relationship with other welding standards
ISO 4063 is commonly used alongside:
- ISO 15614 (welding procedure qualification)
- ISO 9606 (welder qualification testing)
- ISO 3834 (quality requirements for welding)
- ISO 2553 (welding symbols on drawings)
- ISO 5817 (weld quality levels)
ISO 4063 provides the process language used by these standards.
Common misunderstandings about ISO 4063
- “It defines how to weld” – it only classifies processes
- “It replaces welder qualifications” – it supports them
- “Trade names are acceptable alternatives” – they can cause ambiguity
- “One number covers all variants” – sub-processes may differ
Correct process identification is critical for compliance and quality.
Benefits of using ISO 4063 correctly
Organisations that use ISO 4063 consistently achieve:
- Clearer welding specifications
- Reduced risk of incorrect process selection
- Better alignment between procedures and qualifications
- Improved audit and inspection outcomes
- Stronger international consistency
It is a small but essential part of effective welding governance.
Next steps
If you work with welding documentation:
- Familiarise yourself with common ISO 4063 process numbers
- Use ISO numbers consistently in WPS, WPQR, and drawings
- Avoid relying solely on informal or trade names
- Ensure welding qualifications match the specified processes
ISOcertified.net provides guidance on ISO welding and fabrication standards, including ISO 4063, how welding process numbers are used in practice, and how they support compliant, high-quality fabrication and inspection.