EN 1090 EXC3 and ISO 3834-2: What They Mean When You Buy Weldments from Asia

There is a question that comes up in almost every first conversation with a European buyer: *"Are you EN 1090 certified?"*

It is a reasonable question and usually the wrong one. For a large share of the parts that get made in Asia and shipped to Europe, EN 1090 does not apply at all, and a supplier who says yes without checking has told you something about their diligence rather than about their capability.

Here is how the boundary actually works.

The test that decides it

EN 1090-1 is a harmonised standard under the Construction Products Regulation, (EU) 305/2011. Its scope is structural steel and aluminium components used as load-bearing parts of construction works. CE marking under EN 1090-1 has been mandatory since 1 July 2014.

So the question is not about the factory. It is about the part:

If you removed this component, would the strength or stability of a building or civil engineering work be affected?

Yes — it is a load-bearing construction product. The CPR applies, EN 1090-1 applies, and it must be CE marked. No certificate, no legal placing on the market.

No — it is outside EN 1090, therefore outside the CPR, and no CE marking is required by that route.

There is an explicit carve-out worth knowing: the CPR does not apply to support structures that exist solely to support machinery and are supplied as part of the machine. A frame that holds a conveyor drive is not a construction product because it happens to be made of steel and bolted to a floor.

Where the line usually falls

Borderline cases are real. A fixed conveyor gallery may be a construction work. A frame that both carries a machine and forms part of a building's load path can go either way. Those decisions belong to your engineer or a notified body, not to your supplier's sales department — and a supplier who confidently tells you a borderline part is fine is telling you they want the order more than they want to be right.

What EXC actually costs you

If your part is in scope, EN 1090-2 assigns it an execution class: EXC1 through EXC4. The class is set by the consequences of failure and the type of loading, and your designer specifies it.

The practical effect of moving up a class is more non-destructive testing, tighter tolerances, more welder and procedure qualification, and considerably more documentation. EXC3 is the common specification for significant load-bearing steelwork; EXC4 is for structures where failure would be catastrophic.

The point for a buyer is this: execution class is a cost driver, and it is often inherited rather than chosen. Drawings get reused. A class that was right for one project gets carried into the next one where it isn't. Before you send an EXC3 package out for quotation, it is worth ten minutes with the designer confirming that EXC3 is what this particular part needs. If it isn't, the saving is real and it costs nothing to find.

ISO 3834 is a different thing, and often the more relevant one

EN ISO 3834 gets mentioned in the same breath as EN 1090 and is regularly assumed to be part of it. It is not the same instrument.

EN 1090 is a route to CE marking under construction products law. It applies to construction products.

EN ISO 3834 is a set of quality requirements for fusion welding. It says nothing about CE marking. It applies to any manufacturer who welds, whether or not the output is a construction product.

ISO 3834 comes in three levels: 3834-2 (comprehensive), 3834-3 (standard) and 3834-4 (elementary). 3834-2 is what a serious fabricator holds.

For machinery components — which is most of what moves from Asia to European OEMs — ISO 3834-2 is the standard that actually matters, and it is what OEM supplier audits are generally built around. It sits on top of ISO 9001 rather than replacing it, and certification is typically valid for three years with annual surveillance audits. Where a fabricator already has documented procedures and qualified personnel, the certification process is measured in weeks rather than years — published timelines from certification bodies commonly fall in the four-to-ten week range, depending on how ready the documentation is.

That difference in timescale is worth understanding when you assess a supplier. A fabricator without EN 1090 may be two years away from it. A fabricator without ISO 3834-2 could have it before your next order ships — or has chosen not to bother, which tells you something else.

The three documents that tell you more than any certificate

Whatever the certification position, these are what a welding engineer would actually ask to see:

The WPS. A welding procedure specification for the joint type, material and thickness range on your drawing. Ask for the one that covers *your* part, not a sample.

The PQR. The procedure qualification record that backs the WPS — the evidence that the procedure was tested and passed. A WPS without a PQR behind it is a document, not a qualification.

Welder qualifications. Certificates to EN ISO 9606-1 or an equivalent, current, and covering the processes and positions your part needs. These expire. Check the dates.

A supplier who can produce these three within a day is a supplier with a welding quality system, regardless of what is framed on the wall in reception. A supplier who takes two weeks and sends something generic is telling you how the job will run.

What to do with all of this

If you are buying machinery components: EN 1090 is probably irrelevant. Ask for ISO 3834-2, the WPS/PQR for your joints, and current welder qualifications. Ask how weld quality is verified and what NDT is done in-house.

If you are buying load-bearing components for construction works: EN 1090-1 certification at the correct execution class is not negotiable, and the obligations under the CPR run through the importer and distributor as well as the manufacturer. That means a non-compliant part is your regulatory problem too, not only your supplier's.

If you are not sure which one you have: apply the test at the top of this article. If it is still ambiguous, that is a question for your engineer or a notified body — and it is worth resolving before the enquiry goes out, not after the parts arrive.

Where we are

Our EN 1090-1 certification is in progress. Until it is issued we do not take work that requires CE marking under the Construction Products Regulation, and we will say so at enquiry stage rather than at delivery.

For machinery components we work to qualified welding procedures with recorded parameters, and we can send the relevant WPS and welder qualifications with the quotation. Our ISO 3834-2 position and certificate details are on our compliance page, kept current.

FAQ

Are you EN 1090 certified? Not yet — it is in progress. If your part is a load-bearing construction product we will tell you straight away that we are not the right supplier today. If it is a machinery component, EN 1090 does not apply to it.

Is ISO 3834 the same as EN 1090? No. ISO 3834 is a welding quality requirement standard. EN 1090 is a route to CE marking under construction products law. A fabricator can hold ISO 3834-2 without holding EN 1090, and for machinery work that is often the right combination.

Who is responsible if a CE-marked part turns out not to be compliant? Under the CPR the obligations run along the whole chain — manufacturer, importer and distributor each carry duties. Importing a non-compliant construction product is not only the supplier's exposure.

Does an ASME U stamp help in Europe? Not for pressure equipment placed on the EU market. That requires CE marking under PED 2014/68/EU, with a notified body involved for higher risk categories. Dual certification is possible but they are two separate routes and have to be planned from the design stage.

Sources Regulation (EU) No 305/2011 (Construction Products Regulation); EN 1090-1 and EN 1090-2; BSI clarification document on the scope of EN 1090-1; EN ISO 3834 series; certification body published guidance on ISO 3834 certification timelines and validity; Directive 2014/68/EU (PED).