Standards library · Updated 4 August 2026 · Free to read
ISO 15614 explained: welding procedure qualification by test
ISO 15614 is the international standard for proving that a welding procedure works, by welding a test coupon under controlled conditions and testing it to destruction. The result is a welding procedure qualification record, and that record defines the range of production welding the procedure is allowed to cover.
In one line
ISO 15614 qualifies the method. ISO 9606 qualifies the person. You need both, and neither implies the other.
What ISO 15614 covers
ISO 15614 is a series, split by process and material. Part 1 covers arc and gas welding of steels and arc welding of nickel and nickel alloys, and is the part most commonly named. Part 2 covers arc welding of aluminium and its alloys. Further parts cover other processes and material groups.
For each qualification the standard defines:
- the test coupon: joint type, dimensions and configuration
- the welding conditions the coupon is welded under, recorded as a preliminary welding procedure specification
- the non-destructive examination applied to the coupon
- the destructive tests: tensile, bend, impact, hardness and macro examination as applicable
- the acceptance criteria for each test
- the essential variables, and the range of qualification each one produces
Pass the tests and you have a welding procedure qualification record. From that record you write the welding procedure specifications that people actually work to on the shop floor, staying inside the qualified ranges.
Essential variables and why they exist
An essential variable is a welding condition that, if changed beyond a defined limit, changes the properties of the weld enough that the qualification no longer applies. Parent material group, welding process, consumable classification, thickness, diameter, position, heat input, preheat and interpass temperature, post weld heat treatment and joint type all behave this way.
The reason this trips people up is that the qualification looks like a permission slip and behaves like a boundary. A procedure qualified on 12 mm plate does not automatically cover 40 mm. A procedure qualified without post weld heat treatment does not cover work that will be heat treated, and the reverse also holds. Changing from one flux cored wire to a different classification can take you outside the range even though the welder cannot tell the difference at the arc.
On any job with more than a handful of joints, the useful discipline is to map the production joints first and design the procedure tests to cover them with as few coupons as the ranges allow. Doing it the other way round, testing first and then discovering the gaps, is how projects end up paying for coupons twice.
The document set, and why the names matter
| Document | What it is |
|---|---|
| pWPS | Preliminary welding procedure specification. The proposal, used to weld the test coupon. |
| WPQR | Welding procedure qualification record. The evidence: what was welded, what was tested, what the results were, and the ranges qualified. |
| WPS | Welding procedure specification. The instruction a welder works to, written inside the ranges of a WPQR. |
Three documents, three jobs. The most common documentation failure on an audit is a WPS produced with no WPQR behind it, or a WPS whose parameters have quietly drifted outside the range of the record it claims to come from. The rules for writing and formatting a WPS sit in a separate standard from the qualification testing, which is worth knowing when somebody asks why the two documents look nothing alike.
Check the edition your specification names. This page explains what ISO 15614 requires and how it sits with the standards around it. It does not reproduce the standard, and clause numbers, the part numbering and tables move between editions. Work from the edition your contract calls up rather than from a website. If you are not sure which edition or even which standard the specification means, ask AWI before anybody strikes an arc.
How this relates to the Australian standards
Australian fabrication uses its own procedure qualification routes, and they are not interchangeable with ISO 15614.
- AS/NZS 1554 allows prequalified welding procedures for a defined range of structural work, so much routine structural fabrication never needs a procedure test at all.
- AS 3992 governs procedure and welder qualification for pressure equipment under AS 1210 and AS 4041.
- ISO 15614 is what an international client, a European design or a global engineering contractor will name.
A procedure qualified under one of these is not automatically acceptable under another. Where a project has mixed requirements, get the acceptance position agreed in writing at the start. It is a cheap conversation before fabrication and an expensive one after.
Related standards
- ISO 9606, qualification testing of welders. The other half.
- AS/NZS 1554, structural steel welding, including prequalified procedures.
- AS/NZS ISO 3834, which requires qualified procedures, controlled WPSs and the records to prove both.
- Welder qualification is not procedure qualification.
Getting a copy of the standard
ISO 15614 is published by ISO and is available in Australia through Standards Australia. It is not free. Buy the part matching your process and material group, and expect to need the general rules and the WPS content standard alongside it.