ISO 3834: quality requirements for welding
ISO 3834 is the international standard with quality requirements for fusion welding of metals, both in the workshop and on site. The standard has three levels of requirements: part 2 (comprehensive), part 3 (standard) and part 4 (elementary). Under EN 1090, the execution class determines which part you must apply.
The current version of the most demanding part is ISO 3834-2:2021 . In the Netherlands, the standard is published as NEN-EN-ISO 3834. Certification bodies that certify ISO 3834 follow the specific accreditation protocol of the RvA (Dutch Accreditation Council) .
Short answer: EXC1 requires ISO 3834-4, EXC2 requires ISO 3834-3, and EXC3 and EXC4 require ISO 3834-2. ISO 3834 does not say how to weld, but how you control the welding process: who welds, according to which method, who checks, and what you record.
Which parts make up ISO 3834?
The series has more parts than the three requirement levels. Part 1 helps you choose, and part 5 lists the documents you must refer to.
| Part | Content | When do you use it? |
|---|---|---|
| ISO 3834-1 | Criteria for choosing the right requirement level | When choosing between parts 2, 3 and 4 |
| ISO 3834-2 | Comprehensive quality requirements | EXC3, EXC4, and markets such as offshore, petrochemicals and rail |
| ISO 3834-3 | Standard quality requirements | EXC2, the most common level in steel construction |
| ISO 3834-4 | Elementary quality requirements | EXC1 and simple welding work |
| ISO 3834-5 | Documents needed to claim conformity | At each requirement level, as a reference list |
Which ISO 3834 part matches which execution class?
EN 1090-2 links the execution class directly to a part of ISO 3834. You therefore do not have to make that choice yourself.
| Execution class | ISO 3834 part | Welding coordination |
|---|---|---|
| EXC1 | Part 4 | No welding coordinator required |
| EXC2 | Part 3 | Responsible welding coordinator required |
| EXC3 | Part 2 | Responsible welding coordinator required, higher knowledge level |
| EXC4 | Part 2 | Responsible welding coordinator required, highest knowledge level |
The tasks of the welding coordinator are set out in ISO 14731. The required knowledge level also depends on the steel grade and the plate thickness. The page on execution classes shows which knowledge level roughly fits which class. A completed example of a welding procedure is on the WPS example under EN 1090 page, and the page on ISO 9606-1 welder certificates covers the welder matrix and its validity.
What does ISO 3834 regulate in practice?
ISO 3834 covers everything around welding work, from quote to record. The subjects are comparable at all three levels. The difference lies in the depth and in how much you must record.
| Subject | What you arrange | Usual standard |
|---|---|---|
| Requirements and design review | Can you make the welds required? Are they correctly shown on the drawing? | Own procedure |
| Welders and operators | Qualified, with the qualification kept up to date | ISO 9606-1 (steel) |
| Welding methods | Described in a WPS, supported by a qualified method | ISO 15614-1 and related standards |
| Welding coordination | Appointed persons with tasks and authority | ISO 14731 |
| Inspection and testing | Checks before, during and after welding | ISO 17637 (visual), ISO 5817 (acceptance) |
| Equipment | Welding equipment maintained and validated where necessary | Own maintenance plan |
| Welding consumables | Storage, drying and traceability | Supplier instructions |
| Nonconformities | Repair, cause and prevention of recurrence | Own procedure |
Template: welding methods overview for ISO 3834
An auditor almost always asks for an overview of your welding methods. The fictional example below shows what such an overview can look like for a steel fabricator working to EXC2.
| WPS no. | Process | Material | Thickness range | Position | Justification | Status |
|---|---|---|---|---|---|---|
| WPS-01 | 135 (MAG, solid wire) | S235 and S355 | 3 to 30 mm | PA, PB | WPQR-2023-01 (ISO 15614-1) | Current |
| WPS-02 | 136 (MAG, flux-cored wire) | S355 | 8 to 40 mm | PF | WPQR-2023-02 (ISO 15614-1) | Current |
| WPS-03 | 111 (manual metal arc) | S235 | 4 to 20 mm | All | WPQR-2021-05 (ISO 15614-1) | Revision needed |
Link a welder matrix to this: which welder is qualified for which process, which position and up to which date. This way you can see at a glance whether you have the right people for a new order. It works in the same way as a competence matrix under ISO 9001.
| Welder | Process | Qualification (ISO 9606-1) | Positions | Next renewal |
|---|---|---|---|---|
| J. Bakker | 135 | Plate, butt weld, single-sided | PA to PF inclusive | March 2027 |
| M. Smit | 135, 136 | Plate, fillet weld, multi-pass | PA, PB | June 2027 |
A welder certificate under ISO 9606-1 must be periodically confirmed by the welding coordinator or another responsible person. If that confirmation is missing, you cannot demonstrate at audit that the qualification still applies. Plan the confirmations in your calendar.
Do you need a separate ISO 3834 certificate for EN 1090?
Not necessarily. For EN 1090, the notified body assesses your welding quality requirements as part of the FPC assessment. A separate ISO 3834 certificate is then not a requirement.
Many companies still take a separate certificate. According to Kiwa , clients in sectors such as petrochemicals, offshore, rail infrastructure and defence often ask for ISO 3834-2. If you also work outside construction, the separate certificate is useful. Combine the audits with your EN 1090 inspection to avoid duplicate work.
What does the auditor want to see for ISO 3834?
An auditor usually follows one order from drawing to dispatch. Make sure you can show the following:
- The appointment of the welding coordinator, with diploma and task list.
- The welding methods overview with WPSs and the underlying qualifications.
- Current welder certificates and confirmations.
- A completed weld inspection: visual inspection and, where necessary, additional testing.
- Recording of a nonconformity and what you did about it, as with a CAPA process.
Common mistakes with ISO 3834
WPSs without justification. A WPS is a work instruction. Without a qualified method behind it, you usually may not use it at EXC2 and above.
A welding coordinator on paper only. The auditor asks the welding coordinator about their role. If they cannot explain which orders they have reviewed, that is a nonconformity.
Expired welder certificates. This is the most common finding. A simple matrix with expiry dates prevents it.
Forgetting welds on site. ISO 3834 also applies to erection welds on the building site. Include them in your procedures.
Frequently asked questions about ISO 3834
Is ISO 3834 the same as a welding diploma?
No. A welding diploma or welder certificate belongs to a person. ISO 3834 concerns the company: how you control the welding process as a whole. Qualified welders are one part of that.
Can I obtain ISO 3834-3 and later scale up to part 2?
Yes. Many companies start with part 3 because they work in EXC2. If you receive orders in EXC3, you extend to part 2. Expect a more senior welding coordinator and more records.
Does ISO 3834 also apply to aluminium?
Yes. ISO 3834 applies to fusion welding of metals in general. For the qualification of welders on aluminium, you use ISO 9606-2 instead of ISO 9606-1.