ISO 3834-2, 3834-3 and 3834-4: requirements and differences

EN ISO 3834 (PN-EN ISO 3834 in Poland) specifies how a company is to organise the welding of metals so that weld quality results from control of the process and not merely from testing the finished joints. It covers work in the workshop and on site, and it is used by manufacturers of steel structures, pressure vessels and rail vehicles, usually because a customer or a product standard requires it. You choose one of three levels: comprehensive quality requirements (part 2), standard (part 3) or elementary (part 4).

Structure of the standard: parts 1 to 6

The requirements an auditor checks are in parts 2, 3 and 4. The others help you choose the level and implement the standard.

Part	Scope	Current edition	Pages (ISO edition)
1	Criteria for selecting the level of quality requirements	ISO 3834-1:2021, PN-EN ISO 3834-1:2022-03	6
2	Comprehensive quality requirements	ISO 3834-2:2021, PN-EN ISO 3834-2:2021-09	11
3	Standard quality requirements	ISO 3834-3:2021, PN-EN ISO 3834-3:2021-09	10
4	Elementary quality requirements	ISO 3834-4:2021, PN-EN ISO 3834-4:2021-09	3
5	Documents with which you must comply under parts 2, 3 and 4	ISO 3834-5:2021, PN-EN ISO 3834-5:2022-04	7
6	Guidelines on implementing the ISO 3834 series	ISO 3834-6:2024, EN ISO 3834-6:2024	19

The 2021 editions introduced editorial corrections, references to part 5 and new wording of clause 16 on calibration and validation. In 2024 part 6 replaced the technical report ISO/TR 3834-6:2007. Part 1 has had a Polish language version since 2023, and part 5 since February 2026.

ISO 3834 is not a quality management system standard and does not replace ISO 9001; you can apply it on its own.

How to choose the level: part 2, 3 or 4

The manufacturer chooses the level, unless the contract or the product standard imposes it. ISO 3834-1 tells you to take into account:

the number and significance of safety-critical products,
the complexity of manufacture,
the range of products manufactured,
the number of different materials,
the risk of metallurgical problems,
the effect of manufacturing imperfections on product performance.

According to TWI, part 2 suits manufacturers whose procedures and materials change from contract to contract, part 3 suits demanding procedures with a narrow product range, and part 4 suits cases where welding is an auxiliary process. For steel structures the level is indicated by EN 1090-2.

Requirements of ISO 3834-2, 3834-3 and 3834-4: table of differences

The table is based on the 2021 editions.

Element	ISO 3834-2 (comprehensive)	ISO 3834-3 (standard)	ISO 3834-4 (elementary)
Review of requirements	product standard, regulations, own requirements, capability to perform	as in part 2	shortened: scope, resources, documentation
Technical review	17 items, including acceptance criteria, WPS, heat treatment, batch testing of welding consumables	17 items, with no mention of batch testing	no separate list
Subcontracting	under the manufacturer's responsibility, with data from both reviews	as in part 2	under the manufacturer's responsibility
Welders and operators	qualified (ISO 9606, ISO 14732)	the same	the same
Welding coordination	required, ISO 14731	required, ISO 14731	no requirement, supervision of production is sufficient
Inspection and testing personnel	non-destructive testing personnel qualified (ISO 9712)	the same	the same
Equipment and maintenance	equipment list, testing of new equipment, documented maintenance plan	equipment list, maintenance in one clause together with suitability	equipment available and kept in working order
WPS and procedure qualification	WPS and qualification before production, document control	WPS and qualification, with no clause on document control	no WPS requirement, welding with the proper technique
Welding consumables	storage procedure in line with the supplier's recommendations, batch testing when the specification requires it	storage, with no clause on batch testing	in line with the supplier's recommendations
Storage of parent materials	protection and preservation of markings	required (clause 12)	no clause
Post-weld heat treatment	record assigned to the product (ISO 17663)	required (ISO 17663)	no clause
Inspection and testing	before, during and after welding, test status	the same layout (14.1 to 14.5)	to the agreed extent, without lists
Nonconformities	repair procedures, re-testing, prevention	required (clause 15)	control of nonconforming products
Calibration and validation of instruments	at set intervals (ISO 17662)	required (ISO 17662)	no clause
Identification and traceability	if required: 11 elements, for example wire batch, welder for each weld	required (clause 17)	no clause
Quality records	14 types, at least 5 years	required (clause 18)	at least 5 years, without a list

Parts 2 and 3 allow you to omit clauses that do not apply to you, for example heat treatment if you do not carry it out. You adopt part 4 in full.

Relationship with EN 1090-2, ISO 14731, ISO 9606-1 and ISO 15614-1

Part 5 lists the supporting standards: ISO 9606 and ISO 14732 for welders, ISO 14731 for coordination, ISO 9712 for non-destructive testing, ISO 15609 for WPSs, ISO 15614 for procedure qualification, ISO 17663 for heat treatment and ISO 17662 for calibration. You may use technically equivalent documents, and the certification body enters on the certificate the standards you rely on.

EN 1090-2 and execution classes

In Poland the current edition is PN-EN 1090-2+A1:2024-10 (EN 1090-2:2018+A1:2024). The execution class determines the part of ISO 3834:

Execution class	Required part of ISO 3834
EXC1	ISO 3834-4, elementary
EXC2	ISO 3834-3, standard
EXC3	ISO 3834-2, comprehensive
EXC4	ISO 3834-2, comprehensive

From EXC2 you need a coordinator in accordance with ISO 14731. You read the required level of their technical knowledge, basic (B), specific (S) or comprehensive (C), from a table in EN 1090-2 (Table 14 in the 2018 edition), depending on the execution class, steel grade and thickness.

EN ISO 14731:2019 (PN-EN ISO 14731:2019-05 in Poland)

It describes the tasks and responsibilities of welding coordination. During certification the body interviews each coordinator and checks evidence of their work; people without an IWE, IWT or IWS diploma go through an extended interview. The names of the coordinators and their level of knowledge usually go into the annex to the certificate.

EN ISO 9606-1:2017 (PN-EN ISO 9606-1:2017-10 in Poland)

Qualification testing of welders of steel (ISO 9606-1:2012). Every 6 months the welding coordinator or the examiner confirms on the certificate that the welder has worked within the range of qualification. Clause 9.3 gives three revalidation options: a) a new test every 3 years, b) every 2 years, testing of 2 welds from the last 6 months of validity, c) no time limit, as long as the welder works for the same manufacturer with a system in accordance with ISO 3834-2 or 3834-3. Option c) is not permitted for pressure equipment of categories II, III and IV under Directive 2014/68/EU.

ISO 15614-1:2017 with amendment A1:2019

Qualification of welding procedures for steels and nickel by a welding procedure test. Level 2 means more testing and a narrower range of qualification than level 1, and it applies when no level has been specified. The result is a WPQR, the basis for your WPSs.

Welding equipment: maintenance, calibration and validation

In part 2, the following requirements, among others, concern equipment:

Equipment list: you enter the main equipment with its parameters, for example the capacity of cranes, the dimensions and temperature of furnaces; for power sources it is enough to give an approximate number for each process.
Testing after installation: you check new or refurbished equipment after installation and document the result.
Maintenance plan: the documented plan covers the items that control the parameters in the WPS: ammeters and voltmeters, gas flow meters, cables, hoses and connectors, wire feeders and liners, the controls of mechanised stations, temperature measuring instruments. Defective equipment must not be used.
Calibration or validation: the instruments you use to assess quality are calibrated or validated at set intervals (clause 16). You check compliance of the work with the WPS using validated instruments. Calibration or validation of the welding machine does not exempt you from this checking.

The details of calibration and validation are described in ISO 17662, in its third edition since September 2025. For arc welding equipment there is EN IEC 60974-14:2018 (PN-EN IEC 60974-14:2019-02 in Poland), the successor to EN 50504:2008. It distinguishes between calibration of displayed readings, validation of set values and consistency testing; you apply it at installation and at intervals you set yourself. Periodic safety inspections are described in IEC 60974-4.

For your maintenance records you need evidence of inspections. As part of our service package we carry out inspections, cleaning and electrical measurements, and with the paid package you receive a measurement report that you attach to your maintenance records. Validation is a separate service: the package has the VALIDATION add-on for it, and before ordering you agree with us which standard it will be carried out to (for example EN IEC 60974-14). If the inspection reveals a fault, you can have the machine repaired at our welding machine service centre.

ISO 3834 certification for a company step by step

The standard itself does not require a certificate; the customer or the product standard requires it. Certification is carried out by accredited bodies; in Poland these include UDT-CERT (the certification arm of UDT, the Polish Office of Technical Inspection), PRS (Polish Register of Shipping; accreditation AC 114 from PCA, the Polish Centre for Accreditation), TÜV SÜD Polska (AC 161) and Łukasiewicz-GIT (the Polish welding institute in Gliwice, AC 029), which also issues certificates in the IIW/EWF system. According to the EA-6/02 M:2022 guidelines this is certification of the manufacturer, not of the product.

Scope. You define the level, product types, product standards, material groups in accordance with CEN ISO/TR 15608, welding processes and coordinators. This data will go into the annex.
Application and contract. Application with a questionnaire, quotation, contract.
Stage 1. Document review, usually without a visit. At UDT, 2 weeks before the audit you send the organisation chart, the scope of the system, a list of processes including subcontracting and a list of sites.
Stage 2. Audit at the workshop: WPSs and WPQRs, welding plans, qualifications, contracts, records, observation of workstations and a technical interview with the coordinator.
Corrective actions. You receive the certificate only after the nonconformities have been closed. At PRS the deadline is usually 90 days, at GIT 3 months, and at UDT no verification within 6 months means repeating stage 2.
Certificate and surveillance. UDT and PRS issue the certificate for 3 years, GIT for 5 years. The first surveillance audit takes place no later than 12 months after certification. You report any change of coordinators, processes or material groups to the body.
Recertification. You submit the application before expiry: at UDT 4 months in advance, at PRS no later than 2 months, at GIT no later than one month.

Typical nonconformities at an audit

Rachwał and Wolniak (Instytut Spawalnictwa, the Polish Welding Institute, and the Silesian University of Technology, 2018) described system nonconformities that translate into defects in joints:

in the review of order requirements: no record, or an incomplete review;
in subcontracting: unclear rules and a subcontractor who has not been given the requirements;
with welders: the range of qualification does not match the joints being welded, or nobody monitors the qualifications;
with equipment: no maintenance, calibration or validation; current and voltage readings differ from the actual values, which can inflate the heat input and cause grain growth in the heat-affected zone;
in the WPS and production plan: incorrect instructions, or no control of parameters;
with materials: poor storage or no identification of parent materials and consumables;
in records: no evidence of heat treatment, testing and repairs.

Before the audit, go through one order with the coordinator from the contract to the test records and check the 6-monthly confirmations on the welders' certificates. Contracts are exactly what the auditor discusses with the coordinator: selection of procedures, testing, heat treatment, qualifications, traceability and subcontracting.

Frequently asked questions

Is ISO 3834 mandatory?

Not by virtue of the standard itself. It is required by product standards, for example EN 1090-2, EN 15085 (rail vehicles) and EN 13445 (pressure vessels), and by customers in contracts.

What is the difference between ISO 3834-2 and ISO 3834-3?

The layout is almost the same. Part 2 has separate clauses on testing of new equipment, maintenance, document control and batch testing of welding consumables; in part 3 maintenance is combined with equipment suitability and the other clauses are absent. In EN 1090-2 part 3 corresponds to EXC2, part 2 to classes EXC3 and EXC4.

Does an ISO 3834-2 certificate cover parts 3 and 4?

Yes. Meeting a higher level means meeting the lower ones, within the scope of products, materials and processes entered in the certificate.

How long is an ISO 3834 certificate valid?

3 years at UDT and PRS, 5 years at Łukasiewicz-GIT; the EA-6/02 M guidelines allow up to 5 years.

Does every welding machine need validation?

No. The note to clause 9.3 of part 2 says that welding equipment is not normally qualified unless so agreed. The standard requires calibration or validation of the instruments you use to check compliance with the WPS (clause 16 of parts 2 and 3). If you read the parameters from the welding machine's display, its calibration is described in EN IEC 60974-14.

EN ISO 3834: welding quality requirements, levels and certification