QUALITY INTL CERTIFICATIONSWPS, PQR and WQT Explained — Welding Documents 101
A WPS (welding procedure specification) is the recipe — the ranges of amps, volts, travel speed, position, joint design and consumables. A PQR (procedure qualification record) is the evidence: actual recorded values and test results that qualify the WPS, per ASME IX / AWS D1.1-style practice. A WQT (welder qualification test) proves the welder can weld within those ranges.
How the welding procedure specification, its qualification record and welder tests connect.
The WPS: The Recipe for Every Weld
A welding procedure specification tells the welder how to make the weld. It is written as ranges, not single values: a range of amps, a range of volts, a range of travel speed, plus the welding position, the joint design and the consumables to be used. Within those ranges the welder adjusts to conditions; outside them, the weld is no longer covered.
That range structure is the whole point. The WPS is what production welding is executed to, and what inspectors inspect to — every parameter on the floor is checked against the window the WPS defines. A fabricator typically holds a library of WPS documents covering its common joints, positions and materials, each qualified for a defined range of application.
When a job arrives, the engineer selects the WPS that fits the joint and material; one does not get written casually on the workshop floor.
The PQR: The Evidence That Qualifies the WPS
A PQR — procedure qualification record — is the document that proves the recipe works. A test coupon is welded while every actual value is recorded: the amps, volts and travel speed actually used, the position, the consumables, the joint as actually fitted. The coupon is then tested, and the results are recorded in the PQR.
The PQR is evidence, not instruction. Nobody welds to a PQR; it exists to show that the WPS ranges it supports were proven by a real weld, made under recorded conditions and tested with real results. This qualification chain is governed by the applicable code — ASME Section IX and AWS D1.1 are the references most UAE fabrication works to, in that style of practice.
A single PQR is typically compiled once, witnessed where required, and then referenced by production WPS documents for years afterwards.
The WQT: Proving the Welder, Not Just the Procedure
The WQT — welder qualification test — answers the question the PQR cannot: can this particular welder produce an acceptable weld? The welder makes a test weld within the ranges of a qualified WPS, and the tested result qualifies that welder for the ranges covered — the positions, the process, the consumable types.
The distinction matters on every UAE shop floor. A perfect procedure in the hands of an unqualified welder produces rejected welds; a qualified welder working outside the WPS ranges produces welds that are technically unqualified, however good they look. Production welds are covered only when both documents are in place, current, and actually being followed.
Welder qualifications are tracked per welder, and site teams check them the way they check certificates — by expiry, by range, and by traceability to the man holding the torch.
How the Three Documents Chain Together
The chain runs strictly one way. The PQR qualifies the WPS: the coupon's actual values and test results prove the ranges. The WPS plus the WQT qualify the production weld: the procedure is proven, and the welder is proven within it. Break any link — an unqualified WPS, an out-of-range parameter, a lapsed welder qualification — and the weld is not qualified, regardless of workmanship.
| Document | Question it answers | Contains | Qualifies |
|---|---|---|---|
| WPS | How should this weld be made? | Ranges of amps, volts, travel speed, position, joint design, consumables | The production weld, together with the WQT |
| PQR | Does the recipe work? | Actual recorded values plus test results | The WPS |
| WQT | Can this welder do it? | Test weld evidence made within WPS ranges | The welder, within stated ranges |
Essential Variables: What Invalidates a Qualification
Essential variables are the parameters that, when changed beyond the qualified ranges, invalidate the qualification and force re-qualification. They come from the same fields the WPS controls: welding position, consumables, joint design, parameter ranges. A change within ranges is normal welding; a change outside them is a new procedure that has not been proven.
The logic is protective. The PQR proved one set of conditions; the applicable code treats a significant departure from those conditions as unproven, because weld properties can shift with position, heat input and consumable in ways the original tests never covered. Essential variables are therefore the guardrail between "qualified" and "assumed".
On projects, essential-variable changes surface as rework triggers: a weld made with the wrong consumable or in an unqualified position may have to be removed and re-welded under a qualified procedure, even where NDT finds no defect.
What Welding Inspectors Review
A welding inspector reviewing these documents works ranges against actuals. The WPS ranges are compared with the parameters actually recorded in production — where the shop records amps and volts, the inspector checks them into the window. The PQR is checked to confirm it supports the WPS as referenced, with its test results intact.
Currency is the second review point. WQTs are checked for validity and expiry per the applicable rules, and for evidence that the welder has continued working within the qualification. A welder qualification that has lapsed under the code's currency rules stops covering production welds until the welder is retested. Inspectors also confirm that the WPS revision on the shop floor is the revision that was approved.
This is why inspector review is document work as much as floor work — the most common findings are gaps between paper and practice, not bad welding.
Documentation Control on UAE Projects
UAE fabrication projects run on document control, and welding paperwork is where it shows most. The contractor maintains a controlled register of WPS documents, each referenced to its supporting PQR, each revision issued and withdrawn formally. Welder qualification records are held per welder and cross-referenced to weld maps, so any weld can be traced to the procedure and the welder who made it.
Client and third-party inspectors audit that register. A missing PQR reference, an uncontrolled WPS revision, or a welder whose qualification cannot be produced all become findings — and on EPC schedules they cost days, not minutes. Fabricators who keep the chain current — PQR to WPS to WQT to weld map — clear welding audits without argument.
The discipline is simple to state and hard to fake: every production weld traces, through documents, to a proven procedure and a proven welder.
Checklist
- Confirm the WPS for the joint is approved and current before welding starts.
- Verify the WPS is supported by a PQR with actual values and test results.
- Check each welder's WQT covers the process, position and consumables in use.
- Check WQT validity and currency per the applicable code rules.
- Monitor actual parameters against WPS ranges during production.
- Treat any parameter outside ranges as an essential-variable event.
- Control consumables against the WPS specification.
- Manage WPS revisions through formal document control.
- Maintain weld maps tracing every weld to its WPS and welder.
- Keep PQR, WPS and WQT records retrievable for audit.
- Re-qualify when essential variables change beyond qualified ranges.
- Brief welders on the ranges they must stay within, not just the drawing.
Frequently Asked Questions
What is the difference between WPS, PQR and WQT?
A WPS is the welding procedure specification — the recipe of ranges for amps, volts, travel speed, position, joint design and consumables. A PQR is the procedure qualification record — the actual recorded values and test results that qualify the WPS. A WQT is the welder qualification test, proving the welder can weld within those ranges. Together they qualify production welds.
Who approves a WPS — fabricator or inspector?
The fabricator prepares and owns the WPS, supported by its PQR evidence. Approval depends on the project: the client's or third-party welding inspector reviews and accepts it against the applicable code — ASME IX or AWS D1.1 style practice — before production welding starts. The inspector does not write the WPS, but verifies it is qualified and followed.
What are essential variables in welding?
They are the parameters whose change beyond the qualified ranges invalidates a qualification: welding position, consumables, joint design, and parameter ranges such as amps and travel speed. Change within the window is normal production; change beyond it means the procedure is unproven for the new conditions, and re-qualification is required before welding continues.
How long is a welder qualification valid?
Validity and currency rules are set by the applicable code and contract rather than by one universal figure. Qualifications carry expiry dates, and codes also apply continuity rules — evidence that the welder has continued working within the qualification. Inspectors check both expiry and currency, and a lapsed qualification requires retesting before further production welding.
Can one PQR support several WPS documents?
Yes. Since a PQR records the actual values and results from one proven test, multiple WPS documents can be supported by it as long as each stays within the ranges that PQR qualified. Fabricators commonly build a family of WPS documents for different joints and positions from the same qualification evidence, per code practice.