EN 1090-1 EXC2 for container buyers

What is EN 1090

EN 1090 is the European harmonised standard that governs the execution of structural steel and aluminium components. It is the bridge between a structural drawing and the physical product that arrives on a truck. If a steel structure is placed on the European market as load-bearing, EN 1090 is the standard that lets it carry a CE mark under the Construction Products Regulation.

The standard has three parts. Part 1 deals with conformity assessment, factory production control, and CE marking; it is the part that turns a workshop into a certified fabricator. Part 2 covers the technical requirements for steel structures, from material specifications to welding to inspection. Part 3 does the same for aluminium. When a buyer reads "EN 1090-1 EXC2" on a quotation, the supplier is claiming two things at once: they hold a Part 1 certificate from a notified body that authorises them to CE-mark structural steelwork, and the work they are pricing falls into execution class 2 under Part 2.

For container buyers the relevance is direct. A shipping container, a fire-and-rescue module, a site office, or a fuel cell on legs is a welded steel assembly that takes load. The frame, the corner castings, the roof bows, and the door rails are all structural. The moment a buyer wants documentation, warranty, or eligibility for a public tender, EN 1090 stops being academic and becomes a paperwork gate.

EN 1090-1 does not specify how to weld a beam. It specifies how a manufacturer runs the factory that welds it, and what evidence is on file to defend the CE mark. Without that evidence, the structure may be sound, but it cannot be legally marketed as a structural component in the EU and EEA.

The four execution classes (EXC1-EXC4)

EN 1090-2 defines four execution classes, EXC1 through EXC4, that scale the rigour of the work to the consequences of failure. The choice of class is made by the designer or specifier before fabrication starts, using a matrix of consequence class, service category, and production category. The worse the outcome of a failure and the harder the structure works in service, the higher the execution class.

EXC1 is the lightest level, for structures whose collapse causes little harm. Farm sheds and light agricultural frames sit here. Welder qualification is required but supervision is minimal, and traceability is loose.

EXC2 is the default for buildings in general. EN 1090-2 is explicit that if no class is specified for a project, EXC2 applies. Residential blocks, offices, warehouses, small bridges, and the great majority of welded steel assemblies in Europe are EXC2. It introduces the requirement for a qualified welding coordinator, weld quality level C to EN ISO 5817, partial traceability of material, and documented welding procedures. This is the class buyers should expect on a serious steel container.

EXC3 raises the bar for structures where fatigue, dynamic loading, or larger consequences come into play. Highway and rail bridges, stadiums, and high-rise primary structures are typical EXC3. Weld quality level B applies, full traceability is required, and the share of non-destructive testing climbs sharply.

EXC4 is the top class, reserved for safety-critical structures where failure would cause catastrophic consequences. Large bridges over busy infrastructure, critical industrial plant, and certain nuclear structures sit here. The control regime is more or less continuous.

A fabricator certified for EXC2 can also produce EXC1 work, but cannot fabricate EXC3 or EXC4 without an upgrade of their certificate and process controls. For container procurement, EXC2 is the right and adequate class for the steel envelope, frame, and corner-fitting assemblies of a transportable or static container. Specifying higher rarely adds value: it adds documentation cost without changing what the container does in service.

What EXC2 actually requires

EXC2 is a package of demands on the fabricator, not a label that can be self-applied. The factory has to demonstrate the following.

A factory production control (FPC) system audited by a notified body. The FPC manual describes how steel enters the building, how it is identified, how it is welded, how it is inspected, and how the resulting product is released. It is the spine of EN 1090-1.

A welding coordinator with the right level of technical knowledge for the work. EN ISO 14731 defines three knowledge levels: basic, specific, and comprehensive. EXC2 typically requires the specific level, which in practice means an International Welding Specialist (IWS) or equivalent qualification. The coordinator is a named person, not a function; audits ask for them by name.

Qualified welders to EN ISO 9606-1 for steel. Each welder holds a qualification that lists the welding process, position, parent material, filler material group, and thickness range they are authorised to weld. Qualifications expire and must be revalidated at fixed intervals.

Welding procedure specifications (WPS), each supported by a procedure qualification record (PQR) to EN ISO 15614-1. A WPS tells a welder exactly what voltage, current, travel speed, filler, gas, and preheat to apply for a given joint. A PQR is the test report that proves the WPS produces a sound weld.

Quality level C welds to EN ISO 5817. Level C is the moderate quality level, mid-band between D (lowest acceptable) and B (used for EXC3). It sets the maximum size of permitted imperfections such as undercut, porosity, and misalignment. Inspection is sample-based, with visual inspection on all welds and NDT on a defined percentage of critical welds.

Partial traceability of material. The fabricator can identify, for any structural component, which batch of incoming steel it came from. Incoming steel is received against a documented purchase order, marked, and recorded.

Material certificates. EN 10204 type 2.2 is often accepted at EXC2, but type 3.1 is the practical norm and the expectation in serious specifications.

Surface preparation and corrosion protection as specified. EN 1090-2 references EN ISO 12944 for paint systems and EN ISO 8501 for surface cleanliness. C3 corrosivity is the default for a container that lives outdoors in continental Europe.

Tanax operates the welding line under ISO 3834-2 production-level qualification with a named welding coordinator, EN ISO 9606 qualified welders on MAG 135, and WPS/PQR documentation for the steel grades used in our containers. The EN 1090-1 EXC2 capability is run from the same Bánovce hall under one quality manual.

EN ISO 3834-2 (the welding side)

EN ISO 3834 is the welding-quality counterpart of EN 1090. It defines what a welding manufacturer has to demonstrate to claim that its welded products are made under controlled conditions. EN 1090-2 calls up EN ISO 3834 directly: EXC2 work must be performed by a fabricator certified to EN ISO 3834-2 or 3834-3.

The standard has three production levels. EN ISO 3834-2 is the comprehensive level, appropriate for load-bearing steel for buildings, transport, and industrial use. EN ISO 3834-3 is the standard level, lighter on documentation, used for non-critical welding. EN ISO 3834-4 is the elementary level, with minimal formal requirements.

The comprehensive level requires a documented welding quality system, qualified welding coordinators, qualified welders, qualified welding procedures, calibrated equipment, controlled consumables, traceable parent materials, formal inspection, non-conformance handling, and records that survive an audit. It is the level at which a welding shop becomes a manufacturing operation: every weld is traceable to a procedure, every welder to a qualification, every batch of steel to a delivery. A fabricator quoting EN 1090-1 EXC2 should be able to show their EN ISO 3834-2 certificate without hesitation. If they cannot, the EXC2 claim is not supportable.

Tanax holds EN ISO 3834-2 certification at the production-level. Welding combines robotic and manual processes: 2 Daihen FD-V8L robots on a 14 m track, a Daihen FD-B6L six-axis robot, and Kemppi MIG and MAG stations for the manual work.

EN ISO 9606 (the welder side)

EN ISO 9606-1 qualifies an individual welder for fusion welding of steels. It tests the welder's manual ability to lay a sound weld in a specified configuration. The output is a certificate listing the parameters under which that welder is qualified: welding process, parent material group, filler material group, product form (plate or pipe), thickness range, welding position, and joint type. Each parameter has a defined range of qualification.

The process codes are from EN ISO 4063. The two that matter most for container fabrication are:

• 111 for manual metal arc welding (MMA) with covered electrodes.
• 135 for metal active gas welding (MAG) with solid wire and active shielding gas, typically CO2 or argon/CO2 mixtures. This is the workhorse process for production welding of carbon steel.

Tanax welders are qualified to EN ISO 9606-1 with MAG 135 as the primary process. Qualifications are revalidated at the intervals set by the standard. The current list of qualified welders is maintained by the welding coordinator and audited annually as part of the EN ISO 3834-2 surveillance.

For a buyer the test is whether the fabricator can produce, on request, the qualification certificate of any named welder who worked on the order. A serious fabricator can do this for any unit shipped, going back several years. A trader who sub-contracts cannot.

Material traceability (EN 10204 3.1)

EN 10204 classifies metallic-product inspection documents. The two types that matter in practice are 2.2 and 3.1. Type 2.2 is a test report based on non-specific inspection; the data is typical for the grade, not from the actual cast supplied. Type 3.1 is an inspection certificate with actual test results on the specific cast or batch, validated by the steel mill's own inspection representative independent of the production department. It carries a unique heat or cast number that can be cross-referenced to the steel that arrived in the workshop.

For EXC2, EN 1090-2 allows type 2.2 for many components, but type 3.1 is the practical standard for any container that will be tendered, audited, or sold into the public sector. A 3.1 certificate ties a specific physical piece of steel back to the mill, with chemical composition and mechanical properties documented for that exact heat.

The chain works like this. The mill issues a 3.1 certificate. The fabricator receives the steel, records the heat number against the incoming-goods log, and marks the material so the heat number stays attached through cutting and welding. The production traveller records which heat went into which part of which container. At shipment, the buyer can ask for the 3.1 certificates of the steel that went into their specific unit.

Tanax issues EN 10204 3.1 certificates for structural steel on request, and supplies them as standard on B2G and defence work. The chain is maintained from the laser cutting table through to final inspection.

How to verify a fabricator

A claim of EN 1090-1 EXC2 is easy to write on a quotation and harder to back up. A buyer who wants to check whether a supplier really runs the standard should ask for four pieces of evidence.

The EN 1090-1 certificate itself. Issued by a notified body whose number appears on the document. It states the scope of certification, including the execution class, the steel grades covered, and the location of the certified factory. Check that the address matches the site where your work will actually be done. A certificate issued to a sister company at a different site is not the same as a certificate on the hall that will weld your container.

The EN ISO 3834-2 certificate. It must be current. Certificates are issued for a fixed period, usually three years, with annual surveillance audits in between. A lapsed certificate is a red flag.

A sample WPS and a sample EN ISO 9606-1 welder certificate. A fabricator that runs the system can produce both inside an hour. One who outsources fabrication will have neither.

An EN 10204 3.1 material certificate. Ask to see a recent one. If they have to ask the steel supplier to retrieve it, incoming-goods control is not in place.

Two questions work as informal probes during a site visit: "who is your welding coordinator and where is their EN ISO 14731 qualification?" and "can you show me a recent non-conformance report and how it was closed out?" The answers, or the inability to give them, will tell a buyer more than a wall of framed certificates. Tanax welcomes site visits to Bánovce nad Bebravou; the welding coordinator and the QA manager walk visitors through the FPC manual, sample documentation, and the certification file.

FAQ

Is EXC2 the same as CE marking? No. CE marking is the legal outcome under the Construction Products Regulation, applied to a structural component placed on the European market. EXC2 is the execution class assigned during design. A fabricator with an EN 1090-1 certificate that covers EXC2 can CE-mark EXC2 components. The CE mark is the badge; EXC2 is the recipe behind it.

Is EXC2 enough for a defence or public-sector container? For the steel envelope and frame, yes. Most defence specifications in CEE call out EN 1090 EXC2 explicitly. What changes for defence work is the layered quality system around the welding: AQAP 2110 on top of ISO 9001, NATO traceability, and tighter document control. Tanax operates AQAP 2110:2017 and holds NSPA CAGE 4094M alongside the EN 1090 EXC2 capability.

My architect asked for EXC3. Should I argue for EXC2? Talk to your designer first. For a container placed on a site as a service module or storage unit, EXC2 is almost always the correct class. EXC3 is appropriate for primary structures that take dynamic or fatigue loading where consequences of failure are higher. Specifying EXC3 on a container without a structural reason raises cost and lead time without changing safety.

What is the difference between MAG 135 and MAG 138? Process 135 is MAG welding with a solid wire electrode. Process 138 is MAG welding with a metal-cored electrode. EN ISO 9606-1 allows movement between 135 and 138 without requalification. The two are functionally interchangeable for the steels and thicknesses used in container work.

Does the EN 1090 certificate apply to the whole company or just one factory? Just one factory. EN 1090-1 is a factory production control certificate, issued for a specific site and a specific scope. A trader who quotes EN 1090 without controlling a certified factory is borrowing the certificate of the workshop they sub-contract to. Always check that the certificate address matches the production address.

How long does a fabricator's EN 1090-1 certificate last? Three years between full re-certification audits, with annual surveillance audits in between. A current certificate must have a date inside that window. If a supplier sends a certificate older than three years without evidence of surveillance, it is not valid.

Is hot-dip galvanising compatible with EXC2? Yes. EN 1090-2 references EN ISO 1461 for hot-dip galvanising and accepts it as a corrosion protection system. The fabricator's FPC has to specify the design rules for galvanising, including vent and drain holes, and the WPS for any post-galv welding. Tanax delivers galvanised containers for HaZZ fire-and-rescue and Police K9 programmes within the same EXC2 framework.