Quality management in welding: EN ISO 3834

Welding is a "special process": you cannot fully verify its result afterwards, not even with non-destructive testing. ISO 9001:2015, Clause 8.5.1 covers exactly this class of process — those "where the resulting output cannot be verified by subsequent monitoring or measurement" — and requires you to validate them. A bolt can be removed and refitted. A weld that exceeds the acceptance criteria cannot: repairing it after production usually means thermally stressing the material again, distorting the geometry, and multiplying the cost. That is why quality in welding does not come from inspecting the finished product. It comes from keeping the process under control from start to finish. The EN ISO 3834 series institutionalizes exactly that, defining the quality requirements a manufacturer shall meet in welded fabrication. This article walks through the logic of 3834, how to choose a level, welding coordination personnel, procedure and personnel records, material control, testing and NDT personnel competence, traceability, and the link to EN 1090 and the directives — in the language of the shop floor.

Note on editions: The standard editions cited in this article and in the list below are those in force at the date of publication. Standards get revised, so always confirm the edition referenced in the contract and the current published edition before applying anything here.

1. What EN ISO 3834 governs, and why

EN ISO 3834 is the series "Quality requirements for fusion welding of metallic materials" (the series was fully revised in 2021: EN ISO 3834-1…-5:2021). It translates the generic quality management framework of ISO 9001 into welding-specific technical requirements. ISO 9001 says "control your process." 3834 makes that concrete: control the welding process through these elements — contract and design review, control of parent and consumable materials (filler material and shielding gas included), approved welding procedures, qualified welders, an inspection and test plan, calibration, and traceability.

Here is the critical point: 3834 is not a product standard, and it gives no acceptance criteria. The question "is this weld acceptable?" is answered by EN ISO 5817 (quality levels). The question "which quality elements shall I put in place?" is answered by 3834. The two complement each other. Confusing them is one of the most common conceptual errors in the field. As an inspector, separating those two layers is usually your first move in an audit: is the finding in front of you a deviation from an acceptance criterion — that is, a defect beyond the acceptance limit — or a break in the quality system itself?

It is worth fixing the terminology right here. A discontinuity is any interruption in the typical structure of the material; the word is neutral and implies no verdict. An imperfection is a discontinuity that has been classified and measured. A defect is an imperfection that exceeds the acceptance criteria and therefore requires rejection and correction. Using these three words interchangeably in a report is one of the most common causes of argument during an audit. Every defect is a discontinuity; not every discontinuity is a defect — the acceptance criteria decide which is which.

2. Structure of the series: 3834-1 through 3834-6

The series has several parts, each with a different function:

EN ISO 3834-1:2021 — Criteria for the selection of the appropriate level of quality requirements. This is the part you turn to when deciding which level applies.
EN ISO 3834-2:2021 — Comprehensive quality requirements (third edition; it cancels 3834-2:2005).
EN ISO 3834-3:2021 — Standard quality requirements.
EN ISO 3834-4:2021 — Elementary quality requirements.
EN ISO 3834-5:2021 — The list of documents (reference standards) that shall be met to claim conformity with 3834-2, -3, or -4.
EN ISO 3834-6 — Guidelines on implementing the series. For a long time this part was published as ISO/TR 3834-6:2007, a non-normative technical report. In 2024 it became a full standard, ISO 3834-6:2024, replacing the technical report. Confirm which version the contract references.

In practice, certification is always against 3834-2, -3, or -4. So when a manufacturer says it holds "a 3834 certificate," what it actually holds is certification to 3834-2.

3. Choosing the level: 3834-2, -3, or -4?

The difference between the three levels is the scope of the requirements and the depth of documentation — not the "value" of the quality. A weld produced under 3834-4 is not necessarily of "lower quality" than one produced under 3834-2. The difference lies in how many of the control elements are mandatory and documented.

EN ISO 3834-1:2021 weighs typical criteria such as these when selecting a level:

The safety criticality of the product and the consequence of failure (pressure equipment, load-bearing steel structures, lifting equipment).
The variety and difficulty of the welding processes used.
The weldability difficulty and variety of the parent materials.
Risks of post-fabrication problems such as cracking and ageing.

A practical rule of thumb: structures carrying significant loads generally call for 3834-2 (comprehensive). At medium risk, 3834-3 (standard) may be enough. Only simple, low-risk work suits 3834-4 (elementary). Pressure equipment needs care, though: the PED text makes no reference at all to EN ISO 3834. The expectation of 3834-2 is not a directive requirement — it is the structure notified bodies and the industry effectively look for in Category II and above.

Often the product standard already fixes the level, and the choice is not yours to make. In steel structures, the determining factor is the execution class (EXC) of EN 1090-2:2018. The EXC is not picked arbitrarily either: Annex B of EN 1090-2 derives the class from a combination of consequence class (CC), service category (SC), and production category (PC). Unless the design states otherwise, the default is EXC2.

4. Welding coordination personnel and EN ISO 14731

Welding coordination is the heart of 3834-2 and 3834-3. But it is not an absolute rule across the whole series: appointing welding coordination personnel is mandatory for EN ISO 3834-2 and 3834-3; EN ISO 3834-4 does not require it by the standard (a contract or customer requirement may still call for one). This is the most direct organizational consequence of choosing a level.

EN ISO 14731:2019 defines the tasks and responsibilities of welding coordination personnel. The "technical authority" for welded fabrication has to be a person — the one who approves the WPS, selects the filler material and shielding gas, manages welder qualification, sets up the testing, and closes out nonconformities.

EN ISO 14731:2019 defines three levels of technical knowledge for coordination:

Comprehensive technical knowledge.
Specific technical knowledge.
Basic technical knowledge.

The standard does not prescribe a diploma; it defines the knowledge level. In practice, IIW/EWF diplomas are the most widely accepted evidence of these levels:

IWE — International Welding Engineer → comprehensive technical knowledge.
IWT — International Welding Technologist → specific technical knowledge.
IWS — International Welding Specialist → basic technical knowledge.

IWP (International Welding Practitioner) does not appear in this scheme. IWP belongs to the practitioner line of the IIW/EWF training ladder and does not map to the coordination knowledge levels of EN ISO 14731. A common field error is to present IWP as a "fourth coordination tier."

Which knowledge level you need depends on the criticality of the product, the material group, the thickness, and the 3834 level. In EN 1090-2:2018 this is not tied to the EXC class alone. It comes from a table that you read by combining the EXC class with the steel grade group and the material thickness: for an EXC2/S355 combination, specific knowledge may be enough, while EXC3 together with high-strength steel and thick sections calls for comprehensive knowledge (IWE level). Read the required level from the relevant table in the standard, not from memory.

What matters is not the person's title but that an appointed, certified coordinator with a written job description actually performs those duties. This is where audits most often find a gap: on paper there is an IWE, but other people signed the WPS approvals, the nonconformity decisions, and the inspection plans — and the coordination chain is broken.

5. Welding procedures: WPS and WPQR

Under EN ISO 3834-2 and -3, every production weld shall be made to an approved WPS (Welding Procedure Specification). Under EN ISO 3834-4, a WPS and procedure qualification are not mandatory by the standard — at the elementary level, only welder/operator qualification is required in every case. Miss this distinction and you either saddle a 3834-4 manufacturer with unnecessary cost or raise an incorrect audit finding.

The content and format of a WPS follow the EN ISO 15609 series. But for the WPS to be valid, it shall rest on evidence. The umbrella standard for qualification methods is EN ISO 15607:2019. That evidence usually comes from a procedure qualification test: you weld a test piece to the EN ISO 15614 series, cut test specimens from it, subject them to destructive and non-destructive testing, and record the results as a WPQR (Welding Procedure Qualification Record). The ASME equivalent is the PQR; in an EN context, use only the term WPQR. An approved WPQR is the WPS's "certificate of validity."

EN ISO 15607:2019 recognizes five routes to qualification in total:

Procedure test — the EN ISO 15614 series. The most common and most widely accepted route.
Qualification based on tested consumables (filler materials) — EN ISO 15610.
Qualification based on previous welding experience — EN ISO 15611. (Note that this is experience from past production, not a test.)
Standard welding procedure — EN ISO 15612.
Pre-production welding test — EN ISO 15613.

All of these routes are in force; the issue is not whether they are current but whether they are accepted. The application standard and the contract decide which route is accepted. EN 1090-2:2018 limits the permitted qualification methods by execution class (verify the relevant table against the standard itself before applying it), and in practice the EN ISO 15610 and 15611 routes are generally not accepted in either EN 1090-2 or PED work.

EN ISO 15614-1:2017+A1:2019 introduces a distinction that directly affects any comparison with ASME: Level 1 is close to the ASME approach and gives wider ranges of qualification, while Level 2 continues the older EN approach with narrower ranges. Which level the contract requires, and which level is recorded on the WPQR, is a point that produces audit findings directly.

On the pressure equipment side there is a widespread misunderstanding: the PED does not impose a qualification standard. What the directive actually requires is that permanent joining procedures and personnel be approved by a competent third party — a notified body (NB) or a recognized third-party organization (RTPO). The EN ISO 15614 series is a harmonized standard, so it carries a presumption of conformity and is the de facto practice. But another code, such as ASME BPVC Section IX, may also be used. In that case, a record produced to ASME IX is equally valid for Category II–IV equipment placed on the EU market, as long as a competent third party has approved it. So ASME IX is not the default for pressure equipment; it is an alternative that follows from the choice of code, and which system applies shall be clearly recorded. One more note: AWS D1.1 is an integrated code in the US code regime — it covers design, procedure and welder qualification, fabrication, and acceptance criteria together. You cannot mix the EN and AWS chains piece by piece.

The discipline that matters: every production WPS shall be linked traceably to a valid qualification record, and the ranges of qualification (thickness, material group, heat input, position, use of backing) shall cover the production conditions.

6. Welder and operator qualification

However good the procedure, you cannot secure quality if the person applying it holds no documented qualification. For manual and partly mechanized welding, welder qualification is documented to the EN ISO 9606 series: EN ISO 9606-1 (ISO 9606-1:2012) for steel, EN ISO 9606-2 for aluminium and its alloys. For fully mechanized and automatic welding, operator qualification falls under EN ISO 14732. Welder/operator qualification is mandatory at all three levels of 3834.

The welding coordinator has two responsibilities here: making sure valid certificates exist for the correct range (material group, thickness, diameter, position, filler material type, backing condition), and tracking the validity regime of those certificates. In EN ISO 9606-1 that regime is not abstract; it is numeric. Continuity of the certificate is confirmed every 6 months by the employer or the welding coordinator, with a signature verifying that the welder has actually worked within the relevant range. The certificate itself is then maintained through the prolongation options the standard defines — where records support it, confirmation every 2 years based on non-destructive or destructive testing; otherwise, retesting every 3 years. Confirm the applicable prolongation option against the contract and the edition of the standard in force; the revision work merging the ISO 9606 series into a single document (ISO/DIS 9606) is still under way.

Production carried out under an expired welder certificate, or one whose 6-month confirmation was never signed, is a major nonconformity in an audit. Welder records, combined with production records showing which welder made which weld to which WPS, form the cornerstone of traceability.

7. Control of parent materials and consumables

3834 explicitly requires you to manage materials before welding. For parent material: the correct material certificate shall be on file, the identity of the material shall be traceable, and storage shall prevent material mix-ups. The certificate type is not arbitrary. The differences between the document types in EN 10204 are clear: type 2.2 is the manufacturer's declaration based on non-specific inspection; type 3.1 is a specific inspection certificate issued by an inspection function independent of the manufacturing department; type 3.2 is additionally validated by the purchaser's representative or a notified body. Which type you need is set by the product standard, the contract, and — under EN 1090-2:2018 — the execution class (3.2 may be required in critical applications); read the table from the standard itself.

For consumables (electrodes, wire, flux, filler material, shielding gas), what counts is this: the type and size shall match the WPS, the manufacturer's certificate shall be available, and correct storage and baking conditions shall be maintained. Keep the concepts apart here. Baking oven temperature and time records are one thing; the temperature of the holding oven (quiver) where electrodes sit after baking is another; and the exposure time after the packaging is opened is a third. 3834 does not give numerical baking temperatures and times — the consumable manufacturer's instructions do. Managing the risk of hydrogen-induced cold cracking through preheat, meanwhile, rests on the EN 1011-2 methodology.

Another frequently overlooked heading is subcontracting. When welding, non-destructive testing, or heat treatment is subcontracted, the responsibility stays with the manufacturer: you shall demonstrate that the subcontractor also meets the relevant requirements (personnel qualification, procedure, calibration), and the subcontractor's records shall sit in the manufacturer's file. Externally performed heat treatment and reports from outside NDT laboratories are among the items that most often generate nonconformities in 3834 audits.

If the shop cannot answer "Which electrode was opened, when was it baked, and how long was it exposed?" with a record, the quality system exists only on paper.

8. Testing, acceptance criteria, and traceability

Plan testing activity at three points in time: before welding (material, consumables, equipment, joint preparation, backing, preheat), during welding (interpass cleaning and temperature, heat input, maintaining preheat temperature throughout the weld), and after welding (visual testing, non-destructive testing, and where required post-heating and/or PWHT verification). Calculating the preheat temperature follows EN 1011-2; the method for measuring and verifying preheat, interpass, and heat treatment temperatures follows EN ISO 13916. Auditors ask for these records directly.

The acceptance criteria come from a separate standard: quality levels for imperfections in fusion welding are defined by EN ISO 5817:2023. Its scope is not limited to steel; it covers steel, nickel, titanium, and their alloys, applies to full-penetration butt welds and all fillet welds at thicknesses of t ≥ 0.5 mm, and excludes beam welding (for steel, the beam welding counterpart is ISO 13919-1). The quality levels it gives, from strictest to most permissive, are B, C, and D. For aluminium and its alloys, the corresponding acceptance criteria come from EN ISO 10042, and that standard covers arc-welded joints only. EN ISO 6520-1 standardizes the naming of imperfection types in fusion welding. Welding symbols and the transfer of testing requirements onto the drawing follow EN ISO 2553:2019 (or AWS A2.4 in an AWS context).

The applicable quality level comes from the EN 1090 chain that forms the backbone of this article. EN 1090-2:2018 links the execution class to the EN ISO 5817 quality level (Table 17): the general framework is EXC1 → D, EXC2 → C (D for certain imperfection types), EXC3 → B, EXC4 → B plus additional requirements. This mapping is the most operational piece of knowledge in this article — but because of the exceptions at individual imperfection level, read the table itself line by line in practice. If you work in the US code regime, AWS D1.1 brings its own acceptance criteria, and those criteria are not interchangeable with EN ISO 5817. The choice of code changes the acceptance criteria, the procedure qualification, and the welder qualification together.

A quality level on its own is not enough; you have to translate it into non-destructive testing. The chain runs like this: method selection (EN ISO 17635) → the technique for applying the method → the acceptance level specific to that method. Visual testing follows EN ISO 17637. In radiographic testing, the technique is EN ISO 17636-1/-2 and the acceptance levels are EN ISO 10675-1. In ultrasonic testing, the technique is EN ISO 17640 and the acceptance levels are EN ISO 11666. Match the acceptance level to be applied against the EN ISO 5817 quality level, and write it into the inspection and test plan (ITP).

Auditors scrutinize who performs the testing just as closely as the method itself. EN ISO 3834-2 requires testing personnel to be competent; in practice that means NDT personnel hold a Level 1, 2, or 3 certificate to EN ISO 9712 in the relevant method, plus a written authorization. Pressure equipment adds a further layer: under PED Annex I, Clause 3.1.3, approval of NDT personnel by a recognized third-party organization (RTPO) is mandatory only for Category III and IV.

Traceability is the common denominator across this whole chain: you shall be able to trace every weld back to its welder, its WPS, its consumable batch, its parent material heat, and its test report. At the comprehensive level (3834-2), traceability is required to the fullest extent; at the elementary level (3834-4) it is required more narrowly, depending on circumstances. Nonconformity management (NCR), corrective action, and calibration records (thermometers, ammeters, baking ovens) are inseparable parts of the same whole. Record retention time shall also be defined and written down: 3834 does not impose a period itself — the manufacturer sets it — but unless the contract or the product standard says otherwise, practice typically works to a minimum of 5 years.

9. The link to EN 1090 and the directives

3834 does not stand alone; it generally operates inside a product or conformity framework.

EN 1090 for steel and aluminium structures: CE marking and factory production control (FPC) for load-bearing steel and aluminium structures run through EN 1090-1:2009+A1:2009, which is the harmonized standard under the Construction Products Regulation / CPR (305/2011). The execution (fabrication) requirements then split by material: EN 1090-2:2018 defines the technical/fabrication requirements for steel structures only, and the counterpart for aluminium structures is EN 1090-3:2019. EN 1090-2 sets welded fabrication requirements by execution class (EXC1–EXC4) and links them directly to the EN ISO 3834 levels. The mapping the standard gives is unambiguous: EXC1 → 3834-4, EXC2 → 3834-3, EXC3 and EXC4 → 3834-2. A higher execution class means a higher 3834 level and more competent welding coordination.
PED (2014/68/EU) for pressure equipment: There are two separate requirements here, and they should not be confused. Approval of permanent joining procedures and personnel by a competent body (notified body or recognized third-party organization / RTPO) is mandatory under Annex I, Clause 3.1.2 for Category II, III, and IV equipment. Approval of NDT personnel by an RTPO is mandatory under Annex I, Clause 3.1.3 only for Category III and IV. Category I and SEP equipment do not call for third-party approval at this level. The PED makes no reference to EN ISO 3834; even so, the 3834 quality framework is the practical way to meet the directive's essential safety requirements and to manage a notified body's expectations.
Railways (EN 15085) and other sectors: Welding on rail vehicles extends 3834 through a sector-specific framework. Manufacturer certification runs through EN 15085-2, and manufacturers are placed in one of the CL1–CL4 certification levels according to the weld performance classes of the joints they produce. Design requirements sit in EN 15085-3, and testing and documentation in EN 15085-5.

So 3834 is the "common language of welding quality," and EN 1090, the PED, and sector standards apply that language in their own product contexts.

From the field

During a pre-audit at a steel structure manufacturer, the picture was familiar: the company had a genuine 3834-2 target, an appointed IWE, and a full WPS/WPQR set in the file. Then we opened the production records, and two breaks in the chain surfaced. First, on a WPS actually in use in the workshop, deviations in current and travel speed had pushed the calculated heat input outside the range the WPQR qualified on the basis of its impact and hardness tests. Nobody had approved that deviation in any traceable way. (EN ISO 15614-1 does not restrict the heat input range in every case — only where impact and/or hardness testing is required, and on this job it was.) Second, nobody had logged baking oven temperatures for the basic-coated electrodes over the previous three weeks. The electrodes were sitting on a shelf in opened packaging, with no record at all of holding oven temperature.

The visual and radiographic testing carried out to EN ISO 5817 turned up no defect on either count. In 3834 terms, both were still system failures: process control had broken down. That is exactly where the inspector's job starts — documenting the deviation that has not yet surfaced in the weld but already exists in the record chain. The corrective actions were straightforward: re-match the production WPSs to their qualification ranges, build the coordinator's approval signature into the production flow, add the heat input calculation to the production record form, and tie consumable baking and holding oven records into the daily routine. That is the price of welding being a "special process": the failure usually starts not in the weld, but in the record chain behind it.

Related standards

EN ISO 3834-1 … 3834-5:2021 — Quality requirements for fusion welding of metallic materials, and selection of the appropriate level.
ISO 3834-6:2024 — Guidelines on implementing the series (replaces the ISO/TR 3834-6 technical report of 2007).
EN ISO 14731:2019 — Welding coordination: tasks and responsibilities (comprehensive / specific / basic technical knowledge levels).
EN ISO 15607:2019 — General rules for the specification and qualification of welding procedures (umbrella standard, five qualification routes).
EN ISO 15609 series — Welding procedure specification (WPS).
EN ISO 15610 — Qualification based on tested consumables (filler materials).
EN ISO 15611 — Qualification based on previous welding experience.
EN ISO 15612 — Qualification by adoption of a standard welding procedure.
EN ISO 15613 — Qualification based on a pre-production welding test.
EN ISO 15614-1:2017+A1:2019 — Qualification by welding procedure test, steels and nickel alloys (Level 1 / Level 2).
ASME BPVC Section IX — Procedure qualification (PQR/WPS) and personnel qualification (where fabrication follows an ASME code).
EN ISO 9606-1 (ISO 9606-1:2012) — Welder qualification, steel.
EN ISO 9606-2 — Welder qualification, aluminium and its alloys.
EN ISO 14732 — Qualification of welding operators and weld setters (fully mechanized and automatic welding).
EN ISO 5817:2023 — Quality levels for imperfections in fusion-welded joints, t ≥ 0.5 mm (steel, nickel, titanium, and their alloys; beam welding excluded).
ISO 13919-1 — Quality levels for beam-welded joints (steel).
EN ISO 10042:2018 — Quality levels for arc-welded joints in aluminium and its alloys.
EN ISO 6520-1 — Classification of imperfections in welds (fusion welding).
EN ISO 17635 — Non-destructive testing of welds: general rules for the selection of methods.
EN ISO 17637 — Visual testing of fusion-welded joints.
EN ISO 17636-1/-2 — Radiographic testing techniques (film / digital detectors).
EN ISO 10675-1 — Acceptance levels for radiographic testing (steel, nickel, titanium, and their alloys).
EN ISO 17640 — Ultrasonic testing techniques and evaluation levels.
EN ISO 11666 — Acceptance levels for ultrasonic testing.
EN ISO 9712 — Qualification and certification of NDT personnel (Level 1/2/3).
EN ISO 13916 — Measurement of preheat, interpass, and heat treatment temperatures.
EN 1011-2 — Recommendations for arc welding of ferritic steels (preheat and hydrogen cracking control).
EN 10204 — Types of inspection document for metallic products (2.2 / 3.1 / 3.2).
EN ISO 2553:2019 / AWS A2.4 — Welding symbols.
EN 1090-1:2009+A1:2009 — CE marking / FPC framework for structural steel and aluminium components (under CPR 305/2011).
EN 1090-2:2018 — Execution of steel structures (technical requirements; EXC → 3834 and EXC → EN ISO 5817 mappings).
EN 1090-3:2019 — Execution of aluminium structures (technical requirements).
EN 15085-2 — Manufacturer certification for welding of railway vehicles (CL1–CL4); related parts are EN 15085-3 (design) and EN 15085-5 (inspection and documentation).
PED 2014/68/EU — Pressure Equipment Directive (Annex I, Clauses 3.1.2 and 3.1.3).
AWS D1.1 — Structural welding code, steel (an integrated code in the US regime; it carries its own acceptance criteria).

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At DoaWise we carry out welding engineering and inspection services to international standards such as EN ISO 3834, EN ISO 15614, EN ISO 9606, and EN 1090, structuring every step — from welding coordination to procedure qualification, from consumable management to traceability — so that it produces recordable, auditable results. Our aim is to secure the "special process" nature of welding inside a systematic, documented quality chain, rather than leaving it to chance.