WPQR: welding procedure qualification
A WPQR is the record that says one thing: the procedure written in the specification was proven on a coupon, and the coupon passed the tests. Without it the specification is a proposal, not a production document.
Short answer
A WPQR (Welding Procedure Qualification Record) comes out of a procedure test to EN ISO 15614-1 for steels and nickel alloys. It holds three things: how the coupon was welded, what the tests returned and — the important one — what range of production that result covers.
The last point is the one people skip, and it is what makes a record useful. A test on one thickness in one position qualifies a whole band around them: a well-planned coupon covers most of the shop's work with a single test, a badly planned one covers a single joint.
How the test runs
- The engineer draws up the pWPS.
- A welder makes the coupon strictly to it, witnessed by an examining body or an inspector.
- The actual parameters are recorded: current, voltage, travel speed, preheat and interpass temperature, time.
- The coupon goes through non-destructive testing, then under the saw for the destructive test pieces.
- Results and the range of qualification go into the record, signed by the examining body.
Those actual parameters in step three matter more than they look: it is they, not the assumptions in the pWPS, that set the qualified heat input band afterwards.
Testing the coupon
| Test | What it shows | Standard |
|---|---|---|
| Visual (VT) | Cap and root profile, surface imperfections | ISO 17637 |
| Radiography (RT) or ultrasonics (UT) | Internal imperfections: porosity, inclusions, lack of fusion | ISO 17636 · ISO 17640 |
| Magnetic particle (MT) or penetrant (PT) | Cracks and surface-breaking discontinuities | ISO 17638 · ISO 3452 |
| Transverse tensile | Joint strength no lower than the parent metal | ISO 4136 |
| Bend | Ductility of the joint, no cracking under deformation | ISO 5173 |
| Impact (KV) | Resistance to brittle fracture at service temperature | ISO 9016 |
| Hardness (HV 10) | Whether the heat-affected zone has hardened too far | ISO 9015-1 |
| Macroscopic examination | The section: penetration, run layout, geometry | ISO 17639 |
Which tests apply depends on material, thickness and requirements: impact testing where the structure works cold, hardness on steels that harden readily. The usual ceiling for non-alloy and low-alloy steels is 380 HV 10; exceeding it normally means the joint cooled too fast — heat input too low, or no preheat. Converting hardness between scales is what the hardness converter is for.
The range of qualification — the part that matters
A record does not qualify one situation but a band around it. The range covers, among others:
- Thickness. For a multi-run weld usually 0.5 to 2 times the coupon thickness; for a single-run weld far narrower, around 0.7 to 1.3.
- Pipe diameter. A test on pipe also covers larger diameters and, above a certain size, plate.
- Material group to ISO/TR 15608 — often neighbouring groups as well.
- Process to ISO 4063: separately for each, with no carry-over from one to another.
- Welding position — a test in the harder position covers the easier ones.
- Consumable, shielding gas, current type and polarity.
- Preheat and interpass temperature — usually from the coupon value downwards or upwards, depending on the variable.
- Heat input — a band around the value measured on the coupon.
- Post-weld heat treatment — if it was applied it belongs to the range; if it was not, the procedure does not cover heat-treated work.
The "0.5 to 2 times" above is the general rule for multi-run welds. The actual limits sit in the tables of EN ISO 15614-1 and depend on the joint type, the process and the level of testing agreed. The 2017 edition introduced two levels — Level 1 with narrower ranges, close to North American practice, and Level 2, the traditional European one. The level is agreed before the test, because it decides how much production the same record will cover.
Who issues it and how long it holds
The test is run and the record signed by an examining or inspection body. The WPQR belongs to the manufacturer: that firm proved that with its equipment, its consumables and its supervision it reaches the required quality, so moving a record to another company does not work as a rule.
The record carries no expiry date. It lapses when an essential variable moves outside the qualified range — and then a new or supplementary test is needed.
A WPQR is not a welder certificate
Two different documents about two different things. The WPQR is about the procedure and says that welding this way gives the required quality. The certificate to EN ISO 9606 is about a person and says that this particular welder can carry that procedure out. On site both are checked — and both have to cover what is actually being welded.
How the certificate code reads and what its range covers — the EN ISO 9606 welder test and the qualification range calculator.
Frequently asked questions
How long does a WPQR stay valid?
It has no expiry date, unlike a welder certificate, which has to be renewed. It stops applying when any essential variable moves outside the qualified range, or when the manufacturer no longer meets the conditions under which the procedure was qualified.
Is another company's WPQR valid for me?
As a rule, no. Procedure qualification belongs to the manufacturer who carried it out: that manufacturer proved that its equipment, its consumables and its supervision reach the required quality. Taking over someone else's WPQR is possible only in narrowly defined cases and needs the agreement of the examining body and the customer.
What thickness does a test on 10 mm cover?
For a multi-run weld the range is normally half to twice the coupon thickness, so roughly 5–20 mm; for a single-run weld it is far narrower, around 7–13 mm. The exact limits are read from the tables of EN ISO 15614-1 — they depend on the joint type and on the level of testing.
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