Three documents, three jobs
Welding documentation gets confusing because three different records are often all called "the procedure". Each has a different job.
- Welding procedure specification (WPS). The instruction to the welder. It states the joint and its preparation, the process, the consumable classification, the welding position, the preheat and interrun temperatures, and the electrical parameters for each run.
- Procedure qualification record (PQR). The evidence that a procedure works. It records how a test piece was welded and the results of the tests it passed.
- Welder qualification record. The evidence that a particular welder can make that weld. A good procedure does not qualify the person using it.
A principal asking for "your WPSs" usually wants all three, plus evidence of who supervises the welding.
Start with the weld category
AS/NZS 1554.1 uses two weld categories: GP (general purpose) and SP (structural purpose). The category is allocated by the designer and should be shown on the drawings. It sets the level of quality assurance and the acceptance levels, and it usually drives the extent of inspection the principal specifies, so confirm it before writing a single procedure.
If the drawings do not state a category, ask. Assuming SP when the designer meant GP costs inspection money. Assuming GP when they meant SP puts the wrong acceptance criteria on the job.
Route one: prequalified procedures
AS/NZS 1554.1 prequalifies certain combinations of joint preparation, welding process, parent material and consumable. In the 2014 edition, the prequalified joint preparations are tabulated in a normative appendix. For each preparation, the table shows which processes are prequalified and the limits that apply to each, such as thickness, position and root gap. A blank cell means that combination is not prequalified.
Used inside all of the standard's conditions (a prequalified preparation, a listed parent material, prequalified consumables, workmanship and preheat to the standard, and a macro test record), a prequalified procedure avoids qualification by mechanical testing. That makes it the cheapest and fastest route for most structural work.
Two points catch people out:
- Prequalified does not mean untested. The 2014 edition still asks for documentary evidence of a satisfactory macro test for a prequalified procedure. If you do not hold one, a test piece has to be welded, sectioned and examined. Read the qualification clause in your controlled copy and keep that evidence with the WPS.
- Prequalified does not mean any steel. Parent materials, consumables and preheat all have to sit inside the standard's provisions. A steel outside the prequalified list, a consumable that is not prequalified for that steel, or self-shielded flux-cored wire mixed with other consumable types takes you out of the route.
Route two: qualification by testing
When a joint, process or material falls outside prequalification, the procedure is qualified by testing. A test piece that represents the production joint is welded and tested, and the results are recorded in a PQR. The tests required are set out in the standard's extent-of-testing table; check it in your controlled copy for your weld type, weld category and steel.
Testing costs more up front, and it can still be the economic choice. A qualified procedure with a tighter preparation or a higher-deposition process can save a lot of weld metal and time on a large job, and it stays in the fabricator's library for future work within its limits.
The standard also provides other methods of qualification, such as relying on the documented results of an earlier qualification. Check the methods listed in your controlled copy, and which ones your principal will accept, before relying on one.
Essential variables: when a procedure stops applying
Every qualified procedure has limits. The standard lists essential variables: changes that mean the procedure no longer applies and must be requalified. Typical examples are a change of welding process, a change of consumable classification, or a parent steel outside the qualified range. Before reusing a procedure on a new job, check the new job against those limits, not just against the joint sketch.
What a complete WPS contains
Whatever the route, a WPS should let a welder and an inspector work from it without guessing. As a checklist:
- Identification, revision, and the standard and weld category it is written to
- Parent material specification, grade and thickness range
- Joint type, preparation and a sketch, including the run sequence
- Welding process and, where it matters, the transfer mode
- Consumable classification and size, and the shielding gas
- Welding position
- Preheat and interrun temperature
- Current type and polarity, current, voltage and travel speed for each run, and the arc energy they produce
- Back gouging and root treatment. On a prequalified preparation, a complete-penetration butt weld welded from both sides has its root gouged to sound metal before the second side, unless a macro shows complete fusion without it.
- Post-weld treatment, if any
- Inspection and NDT requirements
- The qualification route and its supporting evidence, including the macro test record for a prequalified procedure
Values such as preheat, dimensions and acceptance limits come from your controlled copy of the standard and from the design. They should never be copied from another company's WPS.
Supervision and welder qualification
AS/NZS 1554.1 also sets requirements for who supervises the welding and how welders are qualified; check the personnel clause in your controlled copy for the qualifications it accepts. Many principals ask for a certified welding supervisor, and some mining principals ask for welder qualification to AS/NZS ISO 9606.1. Find out what your principal requires at tender stage, because welder testing takes time to arrange.
How to choose
- Confirm the standard and the weld category from the drawings and the specification.
- Check whether each combination of joint preparation, process, position, parent material and consumable is prequalified.
- Use prequalified procedures wherever they fit. They are usually the cheapest route.
- Qualify by testing where the job falls outside prequalification, or where the weld volume justifies a more productive procedure.
- Keep the evidence (macro records, PQRs and welder qualifications) filed with the WPS, ready for the principal's review.
Where Veristruct fits
Veristruct prepares WPS and PQR documentation, weld maps and ITPs for fabricators and maintenance teams, as fixed-scope packs with turnaround from three business days of complete information. Qualification and approval stay with you and your principal. If you would rather produce WPSs in-house, the Veristruct WPS Tool drafts a WPS in three steps from the joint preparations and processes the standard tabulates as prequalified. You complete it from your controlled copy and keep the evidence, including the macro test record, that makes it prequalified.
This article describes AS/NZS 1554.1:2014 in general terms. It does not reproduce values from the standard and is not a substitute for a controlled copy. Always check the current edition and its amendments.