Welding Procedure Qualification and Welder Certification: What WPS, PQR, and WPQ Really Mean
When sheet metal welded products enter fields with high safety and traceability requirements—cabinets, rail transit, pressure equipment, new energy, and medical equipment—customers and third-party auditors often raise one requirement: provide welding procedure qualification records and welder qualification certificates. Many sheet metal companies have previously produced parts based only on the skill of an experienced welder, and they are at a loss when this requirement appears. In fact, welding procedure qualification is a standardized and repeatable technical management method whose purpose is to prove that “this material, this thickness, and this joint configuration can produce an acceptable weld with this parameter set.” Based on Minshuo Smart Manufacturing’s practice in welding quality management, this article explains the core concepts and implementation points.
1. Why Welding Procedure Qualification Is Needed
Weld quality cannot be established by trial and error, and certainly not by feel. Procedure qualification creates value in three ways:
| Purpose | Description |
|---|---|
| Technical validation | Uses test data to prove that the welding procedure meets mechanical-property requirements |
| Quality traceability | Every weld can be traced to its procedure document and welder |
| Market access | A prerequisite for export, certification, tendering, and customer audits |
For a sheet metal company, the practical significance is this: it turns “one particular welder can do it well” into “any qualified welder following the document can do it well.” This is the dividing line between workshop-style production and standardized manufacturing.
Minshuo Smart Manufacturing reminder: We have seen companies rush to qualify procedures only when a customer audit is imminent. When the test pieces fail or the schedule is too tight, they lose the order. Procedure qualification should be built in advance as routine capability, not treated as an emergency project.
2. The Four Core Concepts
| Abbreviation | Full name | Meaning | Role |
|---|---|---|---|
| pWPS | Preliminary Welding Procedure Specification | Preliminary welding procedure specification | Draft prepared before qualification to guide test-piece welding |
| WPS | Welding Procedure Specification | Welding procedure specification | Formal document released after successful qualification, used to direct production |
| PQR | Procedure Qualification Record | Procedure qualification record | Original record of test-piece welding parameters and test results |
| WPQ | Welder Performance Qualification | Welder performance qualification record | Certificate or record proving a welder’s capability for the relevant scope |
Their relationship can be summarized as follows:
pWPS (draft) -> Weld test piece -> Testing -> PQR (qualification record) -> WPS (formal procedure)
|
Welder works to the WPS
|
WPQ (welder certificate) proves the capabilityKey distinction: A PQR is evidence—it records what was done and what the results were. A WPS is an instruction—it specifies what should be done in production. A WPS must be supported by a PQR, but a PQR is not a WPS.
3. Common Qualification Standards
Different markets and industries use different standards. The common ones are:
| Standard | Scope | Typical region / industry |
|---|---|---|
| ISO 15614-1 | Procedure qualification for arc and gas welding of steels and nickel alloys | Europe, internationally used |
| ISO 9606-1 | Qualification testing of welders for fusion welding of steels | Europe, internationally used |
| ISO 14731 | Welding coordination—tasks and responsibilities | EU CE certification system |
| EN 1090-2 | Execution of steel structures, including welding requirements | EU structural steel |
| ASME BPVC Section IX | Welding, brazing, and fusing qualifications | USA, pressure equipment |
| AWS D1.1 | Structural welding code—steel | USA structural steel |
| NB/T 47014 | Welding procedure qualification for pressure equipment | Domestic pressure vessels |
| GB/T 19869.1 | Welding procedure tests for steels and nickel alloys | Domestic general use |
Selection principle: The applicable regulation and customer requirement determine the standard, not the company’s own preference. If the same batch serves both the EU and US markets, qualification under both the ISO and ASME systems may be required.
4. Complete Qualification Workflow
Determine qualification needs (material, thickness, joint, process, standard)
-> Prepare the pWPS
-> Weld the test piece (by a skilled welder following the pWPS)
-> Visual inspection
-> Non-destructive testing (if required)
-> Mechanical testing (tensile, bend, impact, etc.)
-> Issue the PQR
-> Prepare and approve the WPS
-> Release for production use4.1 Key Points at Each Stage
| Stage | Key points |
|---|---|
| Determine needs | Define material group, thickness range, welding process, joint type, and position |
| Prepare pWPS | Parameters must be specific and executable; avoid vague wording such as “suitable” or “appropriate” |
| Weld test piece | The test piece should be welded by a skilled welder with full recording of actual parameters |
| Visual and NDT | Perform as required by the standard; failures must be analyzed before re-testing |
| Mechanical testing | Typically tensile and bend tests, with impact and hardness added when required |
| Issue PQR | Record actual parameters and test results, signed by the testing body or the company’s technical authority |
| Approve WPS | Reviewed and approved by qualified personnel and incorporated into the quality system |
4.2 Representativeness of the Test Piece
The qualification test piece must represent actual production, which mainly means:
- The material group is the same (grouped per the standard, not merely by trade name).
- The thickness is within the qualified range.
- The joint type and groove dimensions are the same.
- The welding position covers production requirements.
- The welding process, polarity, and shielding gas are the same.
- Preheating, interpass temperature, post-heating, and post-weld heat treatment are the same.
5. Essential Variables and Qualification Range
The core logic of procedure qualification is the “essential variable.” As long as essential variables stay within the permitted range, the existing qualification remains valid. Once a variable moves outside that range, requalification is required.
5.1 Common Essential Variables
| Category | Example variables |
|---|---|
| Material | Material group, category, impact-toughness requirement |
| Dimensions | Base-metal thickness, weld-metal thickness, pipe diameter |
| Design | Joint type, groove angle, backing, welding position |
| Process | Welding method, current type and polarity, heat input |
| Filler | Filler classification, type, shielding-gas composition and flow |
| Heat treatment | Preheat temperature, interpass temperature, post-weld heat treatment |
5.2 Regarding Thickness Coverage
After qualification, one test piece can cover a certain thickness range. A commonly cited rule is “0.5T to 2T of the test-piece thickness,” but the specific range and its conditions are defined by the clauses of the applicable standard, and they differ between standards.
Practical advice: Rather than repeatedly calculating coverage, qualify the thicknesses commonly used in your company—for example 2 mm, 3 mm, 5 mm, 8 mm, and 12 mm—and build your own qualification matrix. It is clearer and more reliable in daily use.
5.3 Example Qualification Matrix
| Material group | Process | Test-piece thickness | Qualified thickness range | Status |
|---|---|---|---|---|
| Carbon steel | TIG | 3 mm | Per applicable standard | Qualified |
| Carbon steel | MIG/MAG | 8 mm | Per applicable standard | Qualified |
| Stainless steel | TIG | 3 mm | Per applicable standard | Qualified |
| Stainless steel | TIG | 6 mm | Per applicable standard | Qualified |
6. Welder Qualification and Validity
Procedure qualification proves the procedure works; welder qualification proves the person can do it. Both are required.
6.1 Content of Welder Qualification Testing
| Item | Content |
|---|---|
| Theory | Welding fundamentals, safety rules, reading of procedure documents |
| Practical | Welding a test plate or coupon as required by the standard |
| Testing | Visual, radiographic or ultrasonic, bend, macro examination, etc. |
| Records | Welding position, thickness, pipe diameter, process, polarity, and so on |
6.2 Common Scope Elements of a Welder Qualification
- Welding process (TIG, MIG/MAG, SMAW, and others)
- Welding position (flat, horizontal, vertical, overhead; pipes use 5G, 6G, and similar)
- Base-metal group and thickness range
- Pipe-diameter range (for pipe work)
- Welding details (with or without backing, single-sided welding with full penetration, and similar)
6.3 Validity and Continuity Requirements
| System | Validity and continuity requirement |
|---|---|
| ISO 9606 system | Certificates are typically valid for 2 years, provided the employer or testing body confirms at the required interval—usually every 6 months—that the welder has continued to work within the qualified scope |
| ASME IX system | Welder qualification may remain valid indefinitely provided the welder performs welding within the qualified scope at least once every 6 months and records are maintained |
| Customer or industry requirements | Some customers require welder certificates to be reviewed every 1-2 years, or issued by a designated third party |
The point most often overlooked: A welder qualification is not finished once the certificate is issued—it is maintained by a continuous work record. If the welder stops performing the relevant work beyond the specified interval, the qualification lapses and retesting or reinstatement is required.
Minshuo Smart Manufacturing experience: We maintain a welder file for each welder recording certificate number, qualified scope, validity period, and monthly actual welding work records. The team leader confirms work continuity once a month, preventing the situation where “the certificate is still within its validity period but the qualification has already lapsed.”
7. Four Key Actions for Implementation
7.1 Establish a Procedure Document System
- Prepare WPS documents classified by product type and material.
- Ensure WPS documents correspond to drawings, process sheets, and inspection standards.
- Documents should carry a number, revision, approver, and effective date.
- Changes must go through approval and be recorded.
7.2 Establish a Welder Qualification Matrix
Consolidate welder certificate information into a matrix with qualified scope on one axis and welder names on the other. When assigning work, it is immediately clear whether a given welder is qualified for the task.
7.3 Establish Welding Parameter Records
- Critical welds should record the actual current, voltage, and gas flow used.
- Welding parameter recorders or digital welding power sources are recommended for automatic logging.
- Records should correspond to the product batch number and weld identification so they are traceable.
7.4 Establish an Audit-Response Mechanism
- Review the customer audit checklist in advance and confirm the required documents.
- Confirm third-party testing and certification lead times early and allow sufficient time.
- Conduct regular internal audits and correct nonconformities promptly.
8. Common Audit Nonconformities
| Nonconformity | Typical manifestation | Corrective direction |
|---|---|---|
| WPS does not match the PQR | Parameters, material group, or thickness range inconsistent | Re-verify and revise the documents |
| Welder working outside the qualified scope | Certificate does not cover the material or thickness | Reassign personnel or arrange additional testing |
| Lapsed welder qualification | Work interruption exceeded the specified interval | Retest or reinstate as required |
| Missing parameter records | Cannot trace the specific welding parameters | Establish a recording system and log critical welds individually |
| Uncontrolled filler-metal management | No batch numbers or drying records | Establish receiving, drying, and issue logs |
| Incomplete heat-treatment records | No preheat or interpass temperature records | Add temperature measurement and recording |
| Confusing document revisions | Obsolete WPS in use on the shop floor | Establish controlled issue and recall of documents |
9. Summary
Welding procedure qualification and welder certification essentially turn welding from an individual skill into an organizational capability. What they deliver is not just certificates but consistent weld quality and repeatable production capability.
Minshuo Smart Manufacturing maintains a complete document and record system for welding: WPS documents covering common material and thickness combinations, a welder qualification matrix updated monthly, and critical weld parameters traceable to the specific welder and batch. For customers with export or certification requirements, we recommend confirming the qualification requirements at project kickoff and completing procedure qualification before production scheduling, so that missing documents do not affect delivery.
The standard clauses described in this article reflect common industry practice. For specific qualification requirements, coverage ranges, and validity periods, refer to the current standard text and the customer’s technical requirements.
