EN 1090 and ISO 3834: which quality level at which execution class
A common misreading is that ISO 3834 only kicks in at EXC2. It does not. EN 1090-2 requires it at every execution class — what changes is the level.
If you fabricate structural steel for the European market, two standards sit on top of each other: EN 1090 takes you to the CE marking, and ISO 3834 governs the welding quality behind it. The relationship between them is where shops most often get the requirement slightly wrong.
The misreading
The story you hear on the shop floor is “ISO 3834 starts at EXC2.” It is close enough to be dangerous. EN 1090-2 does not switch ISO 3834 on at a threshold — it requires it at every execution class, and scales the level with the class:
- EXC1 → ISO 3834-4 (elementary quality requirements)
- EXC2 → ISO 3834-3 (standard quality requirements)
- EXC3 and EXC4 → ISO 3834-2 (comprehensive quality requirements)
So an EXC1 job is not exempt from ISO 3834; it sits at the elementary level. The practical difference between the levels is how much of the welding quality system has to be documented and demonstrated — from a light touch at level 4 to the full welding-coordination, procedure-control and traceability apparatus at level 2.
Why the execution class is the thing to get right first
Because it drives almost everything downstream: the ISO 3834 level, the inspection extent, the tolerances, and the documentation a notified body will assess as part of your factory production control. The class itself comes from consequence of failure, service category and production category (EN 1090-2 Annex B) — not from a gut feel about how important the job looks.
Assign the class wrong at the quote stage and the error propagates: the wrong ISO 3834 level, the wrong procedure and welder ranges, the wrong examination extent. Catching it at the audit is expensive. Catching it because the system knows the class and derives the rest is not.
What this means for your records
Whatever the class, the same questions get asked two years later: which procedure covered this joint, in which revision; which welder made it, qualified in a range that actually contains it; where the material came from, with the inspection document the specification required; and that the examination happened at the extent the class demands. That is a records problem before it is a welding problem — and it is the one worth building your quality system around.
Worgify tracks the execution class per component, derives the ISO 3834 level and the examination extent from it, and keeps the qualification records so that the answer to each of those questions is a lookup, not a search.