EN 1090 Execution Classes Explained: EXC1, EXC2, EXC3 and EXC4 – Complete Guide for Structural Steel Manufacturers
Table of Contents
- What Are EN 1090 Execution Classes?
- Why Execution Classes Matter?
- EXC1
- EXC2
- EXC3
- EXC4
- Comparison Table
- How to Select the Correct Execution Class
- Frequently Asked Questions
- Conclusion
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Introduction
EN 1090 is one of the most vital European standards concerning the manufacturing and erection of steel and aluminium structures. Any manufacturer willing to supply any components of structures to European Economic Area (EEA) should be EN 1090-compliant to receive CE Marking. One of the most important aspects that must be considered is an Execution Class (EXC).
It defines quality control, welding, inspection, personnel and documentations needed for your project. Proper selection of an execution class is mandatory for the safety of your construction, regulation compliance, and positive outcome of certification.
There are plenty of manufacturers, fabricators, exporters and engineers who know what EN 1090 Certification is; however, they have no clear ideas of differences between EXC1, EXC2, EXC3 and EXC4. Wrong choice of execution class may lead you to additional costs, audit reports, time losses, etc.
This guide will introduce the reader to EN 1090 execution classes. It will explain when these or those classes should be used, key requirements for each class, some examples and methods for manufacturers’ classification.
What Are EN 1090 Execution Classes?
Execution Class is a classification system established under EN 1090 for the determination of the technical and quality demands of structures made from steel and aluminium, depending on their application, complexity, and consequences if failure occurs.
There are four types of execution classes:
EXC1 – Lowest standards
EXC2 – Standard standards
EXC3 – Elevated standards
EXC4 – Highest safety critical standards
This classification system affects:
1.Requirements for welding
2.Requirements for the welder qualification
3.Factory Production Control (FPC)
4.Inspection and testing procedures
5.Material traceability
6.Documentation control
The major function of execution class systems is to make sure that the standards for quality are aligned with possible consequences.
Why EN 1090 Execution Classes Matter
Classes of execution are vital for structural integrity and safety.
Improved Structural Safety
Class of Execution that are higher require greater controls, which results in lower defects and structures failures.
Conformity to EU Requirements
Manufacturers offering structural steel products in Europe have to show their conformity to appropriate EN 1090 standards.
Greater Quality Control
Execution Class is used to determine inspection, tests and verifications needed throughout the manufacturing process.
Effective Risk Management
More safety-critical projects need stricter quality assurance procedures.
Market Opportunities
Right choice of execution class will lead to successful CE marking and European markets penetration.
EN 1090 Execution Classes Comparison Table
| Execution Class | Typical Application | Risk Level | Inspection Requirements | Documentation Level |
| EXC1 | Agricultural buildings, storage sheds | Low | Basic | Limited |
| EXC2 | Agricultural buildings, storage sheds | Medium | Standard | Moderate |
| EXC3 | Bridges, stadiums, railway structures | High | Enhanced | Extensive |
| EXC4 | Bridges, stadiums, railway structures | Very High | Maximum | Comprehensive |
EXC1
The class of execution requirements EXC1 stands at the bottom of EN 1090 and is designed for structures that pose no major threat in case of failure in relation to persons, property, or nature.
Applications of This Execution Class
- Agricultural buildings
- Sheds
- Workshops
- Temporary structures
Important Features
- Basic welding requirements
- Limited inspection requirements
- Less inspection
- Simpler documentation
- Sample Scenario
An equipment storage shed for agriculture located in an area without significant risks can be categorized as EXC1.
Example:
Even though EXC1 does not contain numerous requirements as do other higher execution classes, the company must follow the requirements of the corresponding EN 1090 parts.
EXC2
EXC2 is the most frequently utilized execution class that covers the largest number of structural steel works around the world.
Applications of This Execution Class
- Commercial buildings
- Industrial buildings
- Storage facilities
- Office buildings
- Shopping malls
Important Features
- Conventional weld quality specifications
- Qualified welding workforce
- Inspections
- Implementation of Factory Production Control system
- Increased documentation level compared to EXC1
Example:
A structural steel manufacturer working on structural elements of a commercial storage facility would normally be governed by EXC2 specifications.
Many companies working on EN 1090 Certification strive for EXC2 execution class as the main one.
EXC3
Exc3 is intended to be applied to structures for which failure might have a substantial impact on public safety, economics, or even infrastructural stability.
Applications of This Execution Class
- Bridges
- Airports
- Stadiums
- Railway infrastructure
- Power plants
Important Features
- Higher quality demands in welding
- Higher demand in inspections/testing
- Better traceability
- Increased documentation
- High demands concerning the qualifications of personnel
Example:
Passenger railway bridges should usually meet EXC3 standards because of their possible effects on safety if the structures fail.
Manufacturers operating under EXC3 will need to demonstrate higher competencies regarding both technical and quality management aspects.
EXC4
The EXC4 execution class is applied to cases in which a structure’s failure might cause catastrophic outcomes.
Applications of This Execution Class
- Nuclear facilities
- Strategic defense infrastructures
- Critical public infrastructures
- Other engineering projects classified as high-risk
Important Features
- Inspections/Testing at maximum levels
- High levels of documentation
- Tracing at maximum levels
- Highest levels in personnel qualifications
- Quality management system at advanced levels
Example:
Components used in the construction of a nuclear power plant would probably need to comply with EXC4 standards.
Given its complexity, the use of EXC4 tends to be rather rare and applies only to special engineering projects.
How to Select the Correct Execution Class
Several considerations affect the choice of execution class:
Impact of Failure
What are the effects of any structural failure to individuals, property, and nature?
Structural Complexity
The more complex the design, the higher the execution class.
Public Interaction
Structures that serve many people can demand higher controls.
Operating Conditions
Environmental challenges can lead to increased quality demands.
Requirements
Project requirements and existing standards determine the required execution class.
Quick Selection Guide
| Project Type | Recommended Execution Class |
| Agricultural Building | EXC1 |
| Warehouse | EXC2 |
| Commercial Building | EXC2 |
| Railway Bridge | EXC3 |
| Stadium | EXC3 |
| Nuclear Facility | EXC4 |
Common Mistakes When Selecting Execution Classes
The most common problems faced by manufacturers include:
Real-World Examples
1.Construction of Warehouse
Execution Class: EXC2
Reason: Commercial construction, average safety requirements.
2.Building of Railway Bridge
Execution Class: EXC3
Reason: Heavy safety concerns and major functionality impact.
3.Nuclear Facility Structure
Execution Class: EXC4
Reason: Severe repercussions in case of any structural failure.
Frequently Asked Questions
1.What are EN 1090 Execution Classes?
EN 1090 Execution Classes represent classifications of construction and assembly of structural steelwork and aluminium structures with respect to their manufacture, welding, examination, and quality control. The four execution classes (EXC1, EXC2, EXC3, and EXC4) depend on the degree of difficulty and risks of failure associated with a particular project.
2.How do EXC1, EXC2, EXC3, and EXC4 differ from each other?
The difference is in quality control measures, welds, inspections, and documentation involved in a particular project. EXC1 refers to low-risk structures, while EXC4 should be applied to critical structures in which case failures may result in adverse consequences.
3.Which EN 1090 Execution Class do commercial buildings and industrial structures need?
The vast majority of commercial buildings, industrial facilities, and warehouses are designed according to EXC2 classification. In rare cases, such projects may require EXC3 or EXC4 classes in accordance with design documents.
4.Do we need EN 1090 certification in order to export structural steel products to Europe?
Yes, we have to provide EN 1090 Certification for any export of structural steel and aluminium products to countries within the European Economic Area (EEA).
5.How can I find out the right EN 1090 Execution Class for my project?
The execution class will be decided based on various criteria like the complexity of structure, purpose, loadings, safety effects, and the effects of structural collapse. Usually, these criteria are considered by structural engineers and FPC experts while planning for any construction project.
6.Does EN 1090 need Factory Production Control (FPC)?
Yes, Factory Production Control (FPC) is an essential aspect of EN 1090.
Related Resources
- EN 1090 Certification for Structural Steel and Aluminium
- ISO 3834 Certification for Welding Quality Requirements
- WPQR & WPS Certification Guide
- EN 15085 Railway Welding Certification
- CE Marking Requirements for Structural Steel Products
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Conclusion
It is important for structural steel and aluminium fabricators to know about EN 1090 execution classes in order to achieve certification and comply with European regulations and CE marking guidelines. Be it EXC1, EXC2, EXC3, or EXC4 projects, choosing the proper execution class guarantees right quality measures and safe structures.
Through Factory Production Control system and welding procedure qualification, along with assistance from experienced certification experts, manufacturers can benefit greatly.