WPS Traceability in Pipe Welding: WPS, PQR, WPQ and Keeping Them on the Weld
wps · pqr · welder qualification · asme ix · iso 9606 · pipe welding
WPS traceability in pipe welding means every weld record shows which welding procedure specification (WPS) was used, at which revision, and that the WPS was qualified (by a PQR) and the welder was qualified (by a WPQ) for that joint. In practice: assign a WPS to each weld, or to the line with per-weld overrides, before welding; check the WPS range covers the material, thickness, diameter and position; check the welder's qualification and continuity; and record the WPS number and revision in the weld register.
This guide explains WPS, PQR and WPQ, what "covered by the WPS" actually means, and where the chain breaks on live projects.
What are a WPS, a PQR and a WPQ?
| Document | What it is | Code reference |
|---|---|---|
| WPS – welding procedure specification | The instructions for making the weld: process, materials, thickness range, filler, preheat, positions, parameters | ASME IX; ISO 15609-1; AWS D1.1 |
| PQR – procedure qualification record | Record of the test weld and its mechanical test results that support the WPS | ASME IX; ISO 15614-1 (as WPQR) |
| WPQ – welder performance qualification | Record that a welder passed a test within certain limits (process, position, thickness, diameter) | ASME IX; ISO 9606-1 |
The WPS tells the welder what to do. The PQR proves the procedure produces sound welds. The WPQ proves this welder can do it. A weld is only traceable to a qualified procedure if all three line up. AWS D1.1 also allows prequalified WPSs for structural work, which skip the PQR when every condition of the prequalification is met.
What makes a weld "covered" by a WPS?
Under ASME IX, each process has essential variables. Change one beyond its qualified range and you need a new PQR. Supplementary essential variables apply when notch toughness (impact testing) is required. Non-essential variables can change with a WPS revision.
Check at least these for every weld:
- Process (GTAW root, SMAW fill and cap, etc.)
- Base metal grouping (P-numbers under ASME IX, material groups under ISO)
- Thickness range qualified, for both base metal and deposited weld metal
- Filler metal (F-number and A-number under ASME IX)
- Preheat and PWHT conditions
- Impact requirements, which bring in supplementary essentials
Diameter and position limits mostly affect welder qualification rather than the procedure. That is why the WPS can be fine and the welder still not qualified for a small-bore overhead joint.
How long does a welder qualification stay valid?
- ASME IX: a welder's qualification for a process lapses if they have not welded with that process for six months or more. It can also be revoked if there is a specific reason to question their ability. Most shops keep a continuity log, updated monthly, to prove it.
- ISO 9606-1: the employer or examiner confirms every six months that the welder has worked within the scope. Revalidation follows one of the routes in the standard, on a two- or three-year cycle depending on the route.
If continuity lives in someone's memory, you will discover the gap during the client's audit.
Where does WPS traceability break on live projects?
| Problem | What happens | Prevention |
|---|---|---|
| WPS revised mid-project | Welds made before and after the change look identical in the register | Record WPS number and revision per weld |
| Thickness out of range | Schedule 160 branch on a line with a WPS qualified up to a thinner wall | Check range at weld assignment, not after |
| Wrong WPS on dissimilar joints | Carbon to stainless joint welded with the CS procedure | Assign per weld, not just per line |
| Welder qualified for a different position | 6G test, but welding 5G is fine; 1G test and welding in position is not | Check WPQ limits against joint position |
| Continuity lapsed | Welder outside six-month window | Monthly continuity check |
| Repair WPS not used | Repair made to production WPS when spec requires a repair procedure | Assign repair WPS on the repair record |
How do you keep WPS assignment tied to the weld?
- Make a WPS matrix for the project: line class, material, thickness range and the WPS that covers it.
- Assign a default WPS per line from the matrix.
- Override per weld where the joint differs (branch, dissimilar metals, thickness change).
- Check the welder against the WPS process and the WPQ limits when recording who welded it.
- Record WPS and revision on the weld record, not only on the traveller.
- Review weekly for welds with no WPS or a superseded revision.
A weld register layout with WPS and welder columns is in the Excel weld register template, and Weld Traceability 101 shows how WPS fits into the full chain.
Which tools manage WPS and welder qualifications?
- Binders and spreadsheets: common, workable for a few dozen welders; continuity tracking is manual.
- Welding management software: dedicated tools for WPS/PQR authoring, welder qualifications and continuity. Strong on the procedure side; often not linked to the drawings.
- Enterprise QA systems: tie qualifications to work orders; heavy setup.
- Drawing-based weld trackers: good at recording which WPS and welder went on which weld; usually not a qualification database.
Most shops end up with two systems: one for qualifications, one for welds. That is fine, as long as the weld record carries the WPS revision and the welder ID that let you check one against the other.
MapWeld sits on the weld side: WPS can be set by system or line with per-weld overrides, and the Issues list flags weld records that are incomplete. Welder qualifications stay in your own records.
FAQ
What is the difference between a WPS and a PQR? The WPS is the instruction. The PQR is the record of the qualification test that proves the WPS works.
Can one WPS be used for several materials? Yes, within the base metal groupings and thickness range it is qualified for.
Does a WPS revision require requalification? Only if an essential (or, when impact testing applies, supplementary essential) variable changes beyond the qualified range. Non-essential changes need a revised WPS but no new PQR.
How often must welder continuity be checked? ASME IX: the qualification lapses after six months without using the process. ISO 9606-1: confirmation every six months. Check at least monthly.
Should the WPS number be in the weld register? Yes, with the revision. It is the only way to show which procedure each weld followed.
MapWeld does this on the PDF isometric, offline: WPS on every weld, gaps flagged.