Welder qualification looks like a formality until the first time a certificate is rejected on site and a welder goes home. Then it becomes a sequence of specific steps, each of which has to be done in the right order, and most of the cost of getting it wrong is in the reordering.
Here is the whole sequence, from a piece of plate to a certificate someone will accept.
Two different things that sound the same
Before anything else, a distinction that causes more confusion than any other part of the process.
Procedure qualification tests the welding procedure. Can this combination of material, process, consumable, preparation, position and heat input produce a sound joint with the required properties? The output is a Welding Procedure Qualification Record — a WPQR (or PQR in ASME terminology) — which supports one or more Welding Procedure Specifications, the WPSs that welders actually work to.
Welder qualification tests the person. Can this welder, using an approved procedure, produce a sound weld? The output is a welder qualification certificate, commonly to ISO 9606 or ASME IX.
They are separate, they have separate standards, and one does not imply the other. A welder cannot be qualified against a procedure that has not itself been qualified — the procedure comes first. Getting this backwards is the single most common sequencing error, and it means the coupon has to be rewelded.
The sequence
1. Establish what you need to qualify for
Every qualification covers a range, not just the exact thing you welded. Material group, thickness, diameter, position, process, consumable type and joint configuration each carry a range of approval defined by the standard.
This is where the money is made or lost, and it is decided before anyone strikes an arc. A single well-chosen test coupon can qualify a welder for a wide band of thicknesses, several positions and a range of diameters. A carelessly chosen one qualifies them for almost exactly what they welded and nothing else.
The classic example is position. Qualifying in a fixed inclined position typically covers a wider range of positions than qualifying flat — so testing in the harder position once is cheaper than testing in three easy ones. Similarly, choosing a thickness near the top of a band can cover everything below it.
Work out the range you need first, then design the coupon to reach it. Not the other way round.
2. Write and issue the WPS
The welder must weld to a documented procedure. That WPS specifies the process, material, consumable and its classification, joint preparation, welding positions, preheat and interpass temperatures, current, voltage, travel speed, and post-weld heat treatment if any.
For welder qualification, this is normally a preliminary WPS supported by an already-qualified procedure. The welder cannot be qualified against a document that does not exist yet, and "we'll write it up afterwards" fails at audit.
3. Weld the test piece, witnessed
The test coupon must be welded under the observation of an examiner or examining body. Unwitnessed welding does not qualify — the entire evidential value of the certificate is that somebody independent watched it being made.
The witness confirms the welder's identity, that the WPS was followed, that the consumables were as specified and properly stored, that preheat and interpass temperatures were met, and that the coupon is marked so it cannot be substituted. That last one sounds cynical and exists for a reason.
4. Visual examination
First test, and the one that ends the most attempts. Undercut, excess reinforcement, incompletely filled groove, poor profile, surface porosity, arc strikes on the parent material — all assessed against the acceptance criteria before any other testing is done.
Nothing proceeds past a visual failure. Sending a visually failing coupon for radiography wastes the radiography.
5. Non-destructive testing
Volumetric examination of the coupon — usually radiographic, sometimes ultrasonic, depending on the standard and the material. Austenitic materials, where ultrasonics is more difficult, more often go to radiography.
Surface NDT may also apply: magnetic particle on ferritic material, penetrant on austenitic.
Where the standard permits it, satisfactory volumetric NDT can substitute for some destructive testing — but not all of it, and the substitution rules are specific. Check them for your standard rather than assuming.
6. Destructive testing
This is where the coupon is consumed, and where the properties are actually demonstrated.
Bend tests — root and face bends, or side bends on thicker sections — open the joint up and reveal lack of fusion, lack of penetration and poor ductility. Assessed on whether the tension surface opens beyond permitted limits.
Macroscopic examination — a section cut across the weld, polished and etched to reveal the weld profile, the fusion boundary, the heat-affected zone and the pass sequence. A macro shows penetration, fusion at the root and toes, and internal defects that survived the earlier steps. For many welder qualifications this is the most informative single test.
Fracture tests — for fillet welds in particular, breaking the joint open to examine the fractured face for penetration and fusion.
Tensile and impact testing — required for procedure qualification, where the mechanical properties of the joint must be demonstrated, and less commonly required for welder qualification, which is testing skill rather than properties.
Sectioning, mounting, polishing and etching a macro is laboratory work with its own turnaround. It is worth knowing that this step, not the welding, usually sets the calendar for the whole exercise.
7. Certificate issue
If everything passes, the certificate is issued, stating the welder's identity, the standard, the process, the material group, thickness and diameter ranges, positions, consumable, and the resulting range of approval.
The range of approval is the part anyone receiving the certificate will actually read. It is what determines whether the welder can do the job in front of them.
ISO 9606 and ASME IX are not interchangeable
Which standard you qualify to is determined by the construction code your work is built to, and moving between them is not a translation exercise.
The philosophies differ. ISO 9606 defines ranges of approval fairly prescriptively, with tables setting out what a given test covers. ASME IX works through essential variables — parameters where a change beyond defined limits requires requalification — which gives more flexibility in some directions and less in others.
The material grouping systems differ too. ISO uses material groups; ASME uses P-numbers and Group numbers. They do not map one to one, so a qualification covering an ISO material group does not translate cleanly into an ASME P-number range.
The practical consequences are worth planning around. A welder qualified to ISO 9606 is not thereby qualified to ASME IX, or the reverse — if you work across both, expect to hold both. Where a project is built to ASME, the procedure qualification must be to ASME IX; an ISO-qualified WPS does not support it. And because the ranges genuinely differ, a coupon designed to maximise coverage under one standard may not be the coupon you would have chosen under the other.
None of this is difficult once it has been decided. It is expensive when it is discovered after the coupons are welded.
Keeping it valid
A welder qualification is not indefinite. Validity depends on continued use of the process, normally confirmed at intervals by a responsible person, with a requirement not to have had a significant break in that welding process. Longer-term revalidation may require evidence of satisfactory work or retesting.
The requirement most often missed is simply the periodic confirmation signature. It is a small administrative act, and an unsigned certificate is as invalid as an expired one.
Where it goes wrong
In roughly the order we see it:
Wrong coupon design. Qualifies for a narrower range than the work requires, discovered when a job needs a position or thickness not covered. Retest.
Procedure not qualified first. Welder tested against an unsupported WPS. Retest.
Unwitnessed welding. Coupon arrives at the lab with no witness record. Retest.
Consumable control. Electrodes not from a controlled oven, or a different classification than the WPS states. Invalidates the test.
Visual failure. Arc strikes on the parent material outside the joint are a surprisingly frequent cause and are entirely avoidable.
Testing split across suppliers. Welding witnessed by one company, NDT by another, destructive testing by a third, certificate assembled by a fourth. Every handover adds days and an opportunity for a gap in the evidence chain.
That last point is why we do the whole sequence in one place. Witnessing, NDT, destructive testing and certification under one quality system, with one set of records — tensile to 600 kN, Charpy impact to 300 J, and macro and micro examination in our own Cumbria laboratory.
One provider, one certificate, one chain of evidence. If you have a qualification programme coming up, talk to us before the coupons are designed — that is the conversation that saves the most money.
