EN ISO 15607 / 15609 / 15610 — The European Framework for WPS and WPQR Qualification
The EN ISO 15607, ISO 15609, and ISO 15610 standards form the backbone of welding procedure specification and qualification across Europe and internationally. Whether you are preparing a Welding Procedure Specification (WPS) for a pressure vessel under PED, a structural component under EN 1090, or a pipeline fabrication project governed by ISO 3834, these three standards define the rules you must follow. Understanding how they interrelate — and how they differ from the ASME Section IX framework many fabricators also encounter — is essential for any welding engineer or quality professional working in global fabrication.
At its core, the framework operates in a logical three-document sequence: a preliminary WPS (pWPS) is prepared before testing, a Welding Procedure Qualification Record (WPQR) is established by testing or an alternative route, and the production WPS is derived from the qualified WPQR. ISO 15607 governs the general rules and qualification methods, ISO 15609 defines the mandatory content of every WPS for each process type, and ISO 15610 provides one of the five permissible qualification routes — qualification by tested welding consumables. This guide explains each standard in depth, walks through the full qualification workflow, and provides practical engineering guidance for implementation.
EN ISO 15607 — The Master Framework Standard
EN ISO 15607 (Specification and qualification of welding procedures for metallic materials — General rules) is the parent document of the entire European welding procedure framework. It does not stand alone as a complete qualification standard; instead, it defines the architecture within which all related standards operate. Every WPS, WPQR, and pWPS produced under this family must comply with ISO 15607 first, then with whichever specific qualification standard is applicable to the route chosen.
What ISO 15607 Defines
The standard establishes four core things. First, it defines the terminology used throughout the series — what constitutes a WPS, a pWPS, a WPQR, and what is meant by qualification. Second, it specifies which welding processes are within scope, covering all arc welding, gas welding, electron beam, laser beam, laser-arc hybrid, and resistance welding processes applied to metallic materials. Third, it defines the relationship between the pWPS, WPQR, and WPS in the qualification sequence. Fourth, and most importantly for engineering practice, it identifies the five permitted methods by which a welding procedure may be qualified.
The Five Qualification Routes (Table 1 of ISO 15607)
ISO 15607 Table 1 lists the five methods available for qualifying a welding procedure. The standard is explicit that using multiple routes simultaneously for the same procedure is not recommended. The selection of the appropriate route depends on material type, joint criticality, application standard requirements, and whether independent witness is required.
| # | Qualification Method | Governing Standard | Applicability | Examiner Required? |
|---|---|---|---|---|
| 1 | Welding procedure test | ISO 15614 series | Universal — can always be applied | Yes (countersignature on WPQR) |
| 2 | Tested welding consumables | ISO 15610 | Limited — Groups 1.1, 8.1, 21, 22.1, 22.2 only; no PWHT, no impact testing | No (manufacturer self-certifies) |
| 3 | Previous welding experience | ISO 15611 | Conditional — documented production history required | Depends on application standard |
| 4 | Standard welding procedure | ISO 15612 | Conditional — pre-qualified procedure from standardisation body | No |
| 5 | Pre-production welding test | ISO 15613 | Special — where test-piece geometry cannot represent production | Yes |
Essential Variables in the ISO 15607 Framework
ISO 15607 distinguishes between essential variables — parameters whose change beyond the qualified range invalidates the existing WPQR — and non-essential variables, which can be adjusted within the WPS without re-qualification. The specific essential variables applicable to each process and each qualification route are listed in the relevant part of ISO 15609 and the qualification standard (e.g., ISO 15614-1). Common essential variables across arc welding procedures include:
| Variable Category | Typical Essential Variables | Impact of Change |
|---|---|---|
| Base material | Material group (ISO/TR 15608), thickness range | New WPQR required if outside qualified group or thickness |
| Filler material | Filler type, classification, diameter range | Change of type or classification triggers re-qualification |
| Welding process | Process number (ISO 4063), transfer mode (for GMAW) | Each process requires its own qualification |
| Joint geometry | Joint type (butt/fillet), weld position, backing | Changing from butt to fillet requires separate qualification |
| Heat treatment | Preheat temperature, PWHT type and temperature range | Change in PWHT condition is always essential |
| Heat input | Range of arc energy or heat input (if specified) | Exceeding upper limit invalidates metallurgical qualification |
| Shielding | Shielding gas type and composition (ISO 14175 group) | Change of gas group may be essential depending on material |
EN ISO 15609-1 — Mandatory Content of an Arc Welding WPS
EN ISO 15609-1 (Welding procedure specification — Part 1: Arc welding) specifies the mandatory content a WPS must contain for all arc welding processes. The standard does not dictate a particular physical form or template layout; it lists the variables that must be addressed, grouped by topic. Other parts of ISO 15609 cover gas welding (Part 2), electron beam (Part 3), laser beam (Part 4), laser-arc hybrid (Part 5), and resistance welding (Part 6). This guide focuses on Part 1 because arc welding covers the great majority of industrial fabrication — SMAW, GMAW/MIG, GTAW/TIG, FCAW, SAW, and PAW are all arc processes under the scope of ISO 15609-1.
Mandatory Variables in a WPS Per ISO 15609-1
The 2019 edition of ISO 15609-1 groups WPS content into the following required fields. Every field listed below must appear in your WPS document; simply writing “N/A” without justification is not acceptable unless the variable genuinely does not apply to the process and joint in question.
| Group | Required Information | Notes / References |
|---|---|---|
| Identification | WPS number, revision, date, WPQR reference number | Traceability back to supporting WPQR is mandatory |
| Base material | Material standard and grade, ISO/TR 15608 group, dimensions (thickness, diameter) | ISO/TR 15608 grouping determines qualification coverage |
| Welding process | Process number per ISO 4063, degree of mechanisation (manual/partly mech./fully mech./automatic) | e.g., 111 = SMAW, 131 = GMAW, 141 = GTAW, 121 = SAW |
| Joint preparation | Joint type, groove geometry, backing type and material, cleaning method | Often cross-referenced to ISO 9692-1 for groove geometries |
| Filler materials | Standard, designation, trade name, diameter, storage requirements | Classification per relevant ISO filler standard (e.g., ISO 636, ISO 14341) |
| Shielding / backing gas | Gas composition or designation per ISO 14175, flow rate range | Applies to root purge gas (backing) as well as shielding gas |
| Welding position | Position designation per ISO 6947 (PA, PB, PC, PF, PG, etc.) | Each position qualification has its own scope of coverage |
| Preheat & interpass | Minimum preheat temperature (°C), maximum and minimum interpass temperature (°C), maintenance temperature if welding is interrupted | See ISO 13916 for measurement methods |
| Welding parameters | Polarity, current (A), voltage (V), wire feed speed, travel speed, run-out length | Ranges rather than single values are permitted |
| Heat input / arc energy | Range of heat input (kJ/mm) if specified; calculated per ISO/TR 18491 | Mandatory for creep-resistant and quenched-and-tempered steels |
| PWHT | Temperature range, heating and cooling rates, hold time, atmosphere | State “None” explicitly if PWHT is not applied; ambiguity creates audit risk |
| Bead sequence | Sketch showing pass sequence, direction of travel, interpass cleaning method | Critical for multi-pass welds; cross-section diagram strongly recommended |
pWPS vs WPS — The Key Distinction
A WPS is considered preliminary (pWPS) until it is supported by a qualified WPQR. Both documents use the same format prescribed by ISO 15609-1, but they have different status. The pWPS may contain target values and ranges that the welder follows during the qualification test weld. The final WPS, derived after qualification, states the approved ranges of qualification as established by the WPQR. You must not issue a pWPS to the production shop floor — only a WPS supported by a valid WPQR is acceptable as a production work instruction.
Heat input control is not always mandatory under ISO 15609-1, but it becomes essential when welding materials sensitive to heat input — in particular quenched-and-tempered steels, creep-resistant Cr-Mo steels such as P91 / Grade 91, and hardenable stainless steels. For guidance on ferrite content control in austenitic stainless welds, heat input control is similarly critical.
EN ISO 15610 — Qualification by Tested Welding Consumables
EN ISO 15610 (Qualification based on tested welding consumables) provides a simplified qualification route for welding procedures involving materials where the primary metallurgical concern is consumable performance rather than complex base material HAZ behaviour. Instead of conducting a full procedure qualification test (which requires welding a test coupon, mechanical testing, and independent witness), the manufacturer may qualify the procedure by demonstrating that the consumables to be used have been independently tested to a recognised standard and that the test data covers the required mechanical properties.
Scope and Limitations of ISO 15610
This route has been deliberately restricted. The 2024 edition limits application to the following material groups per ISO/TR 15608:
| ISO/TR 15608 Group | Material Description | ISO 15610 Applicable? |
|---|---|---|
| 1.1 | Normalised/thermomechanically rolled fine grain steel, Re ≤ 275 MPa | Yes |
| 8.1 | Austenitic stainless steels, Cr ≤ 19%, Ni ≤ 12% | Yes |
| 21 | Pure aluminium | Yes |
| 22.1 | Non-hardenable wrought aluminium alloys | Yes |
| 22.2 | Hardenable wrought aluminium alloys (age-hardening) | Yes |
| 2.x to 7.x | Quenched & tempered, Cr-Mo, creep-resistant, high-strength alloy steels | No |
| 8.2, 8.3, 9.x, 10.x | High-alloy austenitic, duplex, ferritic-austenitic stainless steels | No |
| 11–46 | Nickel alloys, titanium, copper, cast iron | No |
In addition to material group restrictions, ISO 15610 is categorically not applicable when any of the following are specified for the joint:
What the Consumable Test Data Must Cover
When using ISO 15610, the manufacturer must obtain test certificates demonstrating that the welding consumable has been independently tested to a recognised consumable standard (e.g., ISO 18274 for solid wire for nickel, ISO 2560 for SMAW electrodes, ISO 14341 for GMAW wire). The test certificate must confirm that the all-weld-metal tensile properties, and where relevant the chemical composition, meet the specification requirements. The consumable test data effectively substitutes for the weld procedure test as evidence that the deposited weld metal will meet the joint requirements.
The Full Qualification Workflow Under EN ISO 15607
Understanding the individual standards is necessary, but engineering competence comes from understanding the complete workflow from initial design intent to an approved WPS on the shop floor. The following sequence reflects current best practice under ISO 15607:2019.
EN ISO 15607 vs ASME Section IX — Key Differences
Fabricators supplying both European and North American markets — common in the oil and gas, power generation, and offshore sectors — frequently need to qualify procedures under both ISO 15607 / ISO 15614-1 and ASME Section IX. The two frameworks share the same basic logic (pWPS → test → qualification record → WPS), but differ in important ways that affect cost, timeline, and documentation.
| Feature | EN ISO 15607 / 15614-1 | ASME Section IX |
|---|---|---|
| Qualification record name | WPQR (Welding Procedure Qualification Record) | PQR (Procedure Qualification Record) |
| Variables documented in record | All variables (essential and non-essential) plus qualified ranges | Essential variables only; ranges stated in WPS, not PQR |
| Independent witness | Examiner countersignature on WPQR required | Manufacturer self-certifies; no independent witness required |
| Qualification levels | Two levels (Level 1 and Level 2) since 2017 revision of ISO 15614-1 | Single qualification level |
| Material classification | ISO/TR 15608 material groups (1–11+ for steels, 21–22 aluminium, etc.) | P-numbers and Group numbers per QW-420 tables |
| Filler classification | ISO filler standards (ISO 636, ISO 14341, ISO 2560, etc.) | F-numbers (QW-432) and A-numbers (QW-442) |
| Process notation | ISO 4063 process numbers (111, 131, 141, etc.) | AWS/ASME process names (SMAW, GMAW, GTAW, etc.) |
| Prequalified procedures | ISO 15612 route available but limited in scope | No prequalified WPS concept in ASME Section IX |
| Alternative qualification routes | Five routes (15610, 15611, 15612, 15613, 15614) | One route: welding procedure test only |
| Impact testing default | Required for most structural and pressure applications | Required when specified by the referencing code or design |
ISO 3834 — The Quality Management Context
EN ISO 15607 and ISO 15609/15610 define procedure documentation and qualification rules, but they say little about how those documents must be managed in a quality system. That is the domain of ISO 3834, the quality requirements standard for fusion welding. Under ISO 3834-2 (comprehensive requirements), every welded product must be traceable to the WPS that governed it, and the WPS must in turn be supported by a valid WPQR. Manufacturers certified to ISO 3834-2 must maintain a controlled WPS register with version history, and production records must show which WPS revision was active for each weld.
A common audit finding in ISO 3834 external assessments is not the absence of a WPS — it is the inability to demonstrate that the correct revision of the WPS was accessible to the welder at the time the weld was made. Electronic document management systems that log document access events address this gap, but for smaller fabricators a signed-off paper transmittal record per job is equally acceptable and often more practical.
Practical Engineering Notes — Common Mistakes and How to Avoid Them
Mistake 1 — Issuing the pWPS as a Production Document
The pWPS is a test planning document. It has no production validity. If your shop floor holds documents titled “pWPS” and welders use them as work instructions, your quality system has a serious non-conformance. Once the WPQR is established and the WPS is derived and approved, retire all pWPS copies from production areas.
Mistake 2 — Not Bracketing Thickness Ranges Correctly
The thickness qualification rules in ISO 15614-1 are frequently misapplied. Qualifying on a 12 mm butt weld test piece does not automatically qualify all thicknesses down to zero. The standard specifies minimum and maximum qualified thicknesses as a function of the test piece thickness and the level of qualification. Build a qualification matrix at project start rather than discovering coverage gaps during the final audit.
Mistake 3 — Using ISO 15610 Where PWHT Is Required
Route 2 (ISO 15610) is explicitly excluded where PWHT applies. If a design engineer subsequently specifies PWHT on a joint that was qualified using ISO 15610, the existing WPQR is invalidated for that joint. This scenario is more common than it should be on projects where the mechanical design and welding engineering teams are not aligned early. Confirm PWHT requirements before selecting a qualification route.
Mistake 4 — Omitting the Examiner Countersignature
Under ISO 15614-1, the WPQR is not valid without the examiner’s or examination body’s countersignature. Some manufacturers complete excellent testing but fail to obtain this signature before the project certification audit. Examination bodies typically have administrative lead times; engage them before testing, not after.
Mistake 5 — Assuming ISO 15607 WPQR Satisfies ASME Section IX
As described above, the two systems are not interchangeable. An ASME customer or code inspector may not accept an ISO WPQR as a substitute for an ASME PQR. If your market spans both systems, qualify under both — or verify with the customer whether they will accept ISO documentation as equivalent before committing to a single qualification test.
Recommended Reference Books
The following titles are widely used by welding engineers and quality professionals working with the EN ISO welding procedure qualification framework.
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