EN 1090 EXC4
Requirements
Structural Steel
What Are EN 1090 EXC4 Requirements for Critical Structural Steel Projects in India?
By First Welding Certification Technical Editorial Team
6 Min Read Time
07 Oct 2026
Table Of Contents
EN 1090 Execution Classes
EN 1090 - EXC1
Basic Execution Requirements
EN 1090 - EXC2
Standard Execution Requirements
EN 1090 - EXC3
Enhanced Execution Requirements
EN 1090 - EXC4
Special Execution Requirements
Introduction
EN 1090 EXC4 represents the highest execution class for structural steelwork under the EN 1090 framework. It is intended for structures, components, or details where the consequences of structural failure are exceptionally serious or where additional quality and assurance requirements are necessary.
Unlike a simple upgrade from EXC3, EN 1090 EXC4 requirements are based on EXC3 with additional project-specific requirements. The applicable requirements should therefore be established in the execution specification before fabrication begins.
For Indian structural steel manufacturers exporting components to European markets, understanding EN 1090 EXC4 requirements is essential for planning, welding, inspection, traceability, documentation, and Factory Production Control (FPC).
What Is EN 1090 EXC4?
EN 1090 EXC4, or Execution Class 4, is the highest execution class defined within the EN 1090 execution framework.
EN 1090-2 establishes four execution classes—EXC1, EXC2, EXC3 and EXC4—with progressively increasing requirements. EXC4 is based on EXC3 and introduces further project-specific requirements where additional assurance is needed.
The execution class can apply to:
- An entire structure
- A structural component
- A specific connection
- A particular detail
Therefore, a project does not necessarily have to assign EXC4 to every component. The applicable execution class should be established within the project execution specification.
In simple terms
EXC4 = EXC3 requirements + additional requirements specified for the particular project or structural application.
This distinction is important because manufacturers should not assume that every EXC4 project follows an identical inspection or documentation checklist.
When Is EN 1090 EXC4 Required?
EXC4 is generally associated with structures or structural details where failure could have extreme consequences or where exceptional assurance requirements apply.
Potential applications can include:
- Critical infrastructure
- Special structural applications
- Highly demanding structural components
- Structures with extreme consequences of failure
- Safety-critical structural details
- Certain major bridge or infrastructure applications, depending on the applicable classification and national/project provisions
The exact selection should come from the design and project requirements rather than from the fabricator’s preference.
Guidance associated with EN 1090 links execution-class selection with factors such as consequence class, service category and production category.
How Is the EXC4 Execution Class Determined?
The EN 1090 execution class is normally established during the design and specification stage.
The selection process considers factors such as:
1. Consequence of failure
The project team evaluates what could happen if the structure, component, or detail fails.
Higher consequences can lead to more demanding execution requirements.
2. Service conditions
The loading and operational conditions of the structure can affect the required execution class.
Static loading, fatigue, seismic actions and other demanding service conditions may influence the classification process.
3. Production category
The complexity and characteristics of manufacturing can also influence execution-class selection.
4. Project-specific requirements
For EXC4, additional requirements can be specified beyond the baseline EXC3 requirements.
Therefore, the EN 1090 EXC4 requirements should be confirmed from the approved execution specification, applicable design standards, contract documents and relevant national provisions.
Key EN 1090 EXC4 Requirements
1. EXC3 Requirements Form the Baseline
The first principle to understand is that EXC4 is based on EXC3.
The manufacturer therefore needs to establish the controls applicable to EXC3 and then identify the additional requirements specified for the EXC4 project.
This can affect:
- Manufacturing procedures
- Welding
- Inspection
- Testing
- Material control
- Traceability
- Documentation
- Quality control
- Verification activities
EN 1090-2’s execution-class table specifically identifies requirements associated with the different classes, while some requirements are selected on a project-specific or detail-specific basis.
2. Enhanced Material Identification and Traceability
Material traceability is a critical element of higher execution classes.
For EXC3 and EXC4, constituent products require stronger traceability controls through the manufacturing process. Identification should remain controlled from receipt through fabrication and handover as applicable to the project requirements.
A manufacturer should therefore establish a documented system for:
- Material identification
- Inspection certificates
- Heat or batch identification
- Material marking
- Transfer of identification during fabrication
- Component identification
- Final documentation
This reduces the risk of losing the connection between the finished structural component and its original material documentation.
3. Welding Control
Welding represents one of the most important areas of EN 1090 EXC4 compliance.
The manufacturer should control applicable welding activities through qualified procedures, qualified personnel and appropriate welding coordination.
Depending on the applicable requirements, the production system may involve:
- Qualified welding procedures
- Qualified welders/operators
- Welding coordination
- WPS control
- WPQR records
- Welding consumable control
- Preheating and interpass temperature control
- Welding inspection
- Non-destructive testing where specified
- Welding records
For EN 1090-2:2018, the execution-class requirements connect higher execution classes with more demanding welding quality-management requirements.
4. Inspection and Quality Control
EXC4 projects require careful planning of inspection and verification activities.
However, it is important not to treat “EXC4” as a single universal NDT percentage.
The required inspection and testing should be established from the applicable EN 1090 requirements, execution specification, structural design, weld category, project documentation and other applicable standards.
Inspection planning can include:
- Visual inspection
- Dimensional inspection
- Welding inspection
- NDT where applicable
- Material verification
- Surface-condition checks
- Bolted-connection checks
- Coating or corrosion-protection inspection
- Final verification
The objective is to demonstrate that the completed component satisfies the specified technical and quality requirements.
EXC4 Documentation and Traceability
Documentation becomes particularly important when working with critical structural components.
For EXC4 projects, the quality documentation should be aligned with the project requirements and applicable EN 1090 provisions.
Relevant records can include:
| Documentation Area | Typical Records |
|---|---|
| Material | Material certificates and identification records |
| Welding | WPS, WPQR and welder qualification records |
| Inspection | Inspection and test records |
| NDT | Applicable NDT reports |
| FPC | Factory Production Control records |
| Manufacturing | Production and process records |
| Nonconformities | NCR and corrective-action records |
| Traceability | Material/component identification records |
| Final quality | Final inspection and release documentation |
EN 1090-2 requires quality documentation for EXC2, EXC3 and EXC4, including elements such as organizational responsibility, procedures, inspection and test planning, change control and nonconformity procedures.
EXC3 vs EXC4: What Is the Difference?
| Requirement Area | EXC3 | EXC4 |
|---|---|---|
| Execution strictness | High | Highest |
| Basic requirements | EN 1090-2 | EN 1090-2 |
| Baseline | EXC3 | EXC3 |
| Additional project requirements | As specified | Further requirements may apply |
| Material traceability | Strong | Strong / project-specific additional controls |
| Welding control | High | High + additional project requirements where specified |
| Inspection | According to applicable requirements | According to applicable requirements + project-specific requirements |
| Documentation | Extensive | Extensive + additional assurance requirements where specified |
| Application | High-consequence structures | Exceptional / special applications |
The most important difference is therefore not simply “more paperwork.” EXC4 is used when the project requires additional assurance beyond the normal EXC3 framework.
EN 1090 EXC4 Certification Preparation Checklist
Before starting an EXC4 project, a manufacturer should review:
Project Requirements
- Execution class clearly identified
- Execution specification available
- Project-specific requirements identified
- Applicable standards confirmed
Material Control
- Material certificates available
- Material identification system established
- Traceability procedure implemented
- Identification maintained during fabrication
Welding
- Applicable WPS available
- Supporting WPQR available where required
- Welder qualifications verified
- Welding coordination established
- Consumable control implemented
Inspection
- Inspection and Test Plan prepared
- Inspection stages defined
- NDT requirements identified
- Dimensional checks defined
- Hold/witness points identified where required
Documentation
- Quality records controlled
- NCR procedure established
- Change-control procedure established
- Traceability records maintained
- Final inspection documentation completed
Frequently Asked Questions
What is EN 1090 EXC4?
EN 1090 EXC4 is the highest execution class in the EN 1090 execution framework. It is based on EXC3 and incorporates additional project-specific requirements where exceptional assurance is required.
Is EXC4 higher than EXC3?
Yes. EXC4 represents the highest execution class. EN 1090-2 describes EXC4 as being based on EXC3 with further project-specific requirements.
Who decides the EN 1090 execution class?
The execution class is established during project design and specification. The structural designer, project stakeholders and applicable regulatory or national provisions can influence the selection. A manufacturer should not independently downgrade the specified class.
Is material traceability required for EXC4?
Yes, higher execution classes require controlled material identification and traceability. EN 1090-2 identifies full traceability requirements for EXC3 and EXC4 in its execution-class requirements.
Can different execution classes exist within one structure?
Yes. EN 1090-2 allows execution classes to apply to an entire structure, part of a structure, component or specific detail.
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Conclusion
EN 1090 EXC4 is intended for structural applications requiring the highest level of execution control within the EN 1090 classification system.
The key point is that EXC4 should not be treated as a generic checklist that applies identically to every project. It is EXC3-based with additional project-specific requirements, which means manufacturers must review the execution specification, applicable standards, design requirements and contractual documentation before production begins.
For Indian manufacturers supplying structural steel components to international markets, effective EXC4 preparation should bring together Factory Production Control, material traceability, welding qualification, inspection, testing, documentation and project-specific quality requirements.
A well-controlled EXC4 manufacturing process allows manufacturers to demonstrate that critical structural components have been produced according to the specified execution requirements.
Planning an EN 1090 EXC4 Project?
First Welding Certification Pvt Ltd (PRVÁ ZVÁRAČSKÁ, a.s.) works with manufacturers seeking structured certification and compliance pathways for welding and structural-steel requirements.
If your project involves EN 1090 EXC4, structural steel fabrication, FPC, welding documentation, traceability or international project requirements, review the applicable requirements before production begins.
Discuss your EN 1090 certification requirements with Us.