Introduction: Why Welding Quality Matters
In industries such as machinery manufacturing, steel structures, energy equipment, and pressure-bearing components, welding is one of the most critical processes that determines the durability, safety, and long-term performance of the final product.
This is why global buyers increasingly demand documented welding control systems, including certified WPS (Welding Procedure Specification) and PQR (Procedure Qualification Record). These documents ensure every weld is executed according to a proven, repeatable, and verified process, regardless of which shift produces it or which welder performs the work.
This article explores how manufacturers can leverage certified WPS and PQR to achieve welding excellence, meet international standards, and build lasting customer confidence.
What Are WPS and PQR?
Welding Procedure Specification (WPS)
A WPS is a comprehensive written document that provides detailed instructions for performing a specific welding operation. Think of it as a precise recipe that specifies every ingredient and step needed to produce a quality weld.
Key elements of a WPS include:
- Base material types, grades, and thickness ranges
- Welding process to be used (GMAW/MIG, GTAW/TIG, SAW, FCAW)
- Filler material specifications (type, classification, diameter)
- Electrical parameters (current, voltage, polarity)
- Welding technique (travel speed, torch angle, weave pattern)
- Preheat and interpass temperature requirements
- Post-weld heat treatment specifications (if applicable)
- Joint design and welding positions
- Shielding gas composition and flow rates
The purpose of a WPS is to ensure that every welder follows the same approved procedure, guaranteeing uniform quality across all welds.
Procedure Qualification Record (PQR)
A PQR is the documented evidence that welds produced using a specific set of parameters will meet required mechanical and quality standards. It records actual data from qualification testing performed on test welds.
A PQR documents:
- Actual welding parameters used during the test
- Materials welded and joint configuration
- Complete mechanical test results:
- Tensile strength values
- Bend test performance
- Impact toughness data (including test temperature)
- Hardness survey across the weld zone
- Macro and microstructure examination findings
- Non-destructive testing results (radiographic, ultrasonic, magnetic particle, or liquid penetrant inspection)
- Testing laboratory information and test dates
- Certification body approval (when applicable)
The Critical Relationship
The relationship between WPS and PQR is fundamental: a PQR validates that a WPS will produce acceptable welds. One PQR can support multiple WPS documents, provided those procedures fall within the qualified parameter ranges established by the PQR testing.
In simple terms, the PQR proves the recipe works; the WPS tells welders how to follow that proven recipe.
Why Certified WPS & PQR Are Essential
Compliance with Global Buyers’ Requirements
European, American, and Japanese customers typically require certified WPS/PQR before approving mass production. Using certified procedures not only ensures quality, it also accelerates audits, inspections, and supplier onboarding.
As we know that European markets operate under strict regulatory frameworks that mandate documented welding procedures:
EN ISO 15614 Series: These standards specify requirements for qualification testing of welding procedures for metallic materials. Different parts address various welding processes and material types.
EN 1090: This standard for structural steel and aluminium fabrication explicitly requires that all welding be performed according to qualified welding procedures. It’s mandatory for UKCA marking of structural products.
Pressure Equipment Directive (PED): For pressure vessels and piping, documented and qualified welding procedures are legally required.
Industry-Specific Standards: Sectors like railways (EN 15085), offshore structures (ISO 19902), and bridges (EN 1993) each have specific welding qualification requirements.
Ensuring Consistent Quality
Certified WPS ensures every weld, no matter the operator, shift, or production batch, is executed using the same parameters verified by testing. It also delivers tangible quality benefits:
Defect Prevention: Properly qualified procedures eliminate the guesswork that leads to common welding defects—cracking, porosity, incomplete fusion, lack of penetration, and excessive distortion.
Performance Assurance: Mechanical testing during PQR qualification verifies that welds will meet design requirements for strength, ductility, and toughness throughout the product’s service life.
Process Control: When parameters are clearly specified and validated, quality becomes measurable and controllable rather than dependent solely on individual welder skill.
Traceability: Documented procedures create a clear audit trail from qualification testing through production, facilitating root cause analysis if issues occur.
Building Customer Confidence
In international trade, certified WPS and PQR serve as a universal language of quality:
Third-Party Verification: Certification by recognised bodies (TÜV, Lloyd’s Register, Bureau Veritas, DNV) provides independent confirmation of capabilities.
Risk Mitigation: Buyers can confidently specify certified procedures in purchase orders, reducing their supply chain risk.
Competitive Advantage: Comprehensive WPS/PQR portfolios demonstrate technical capability and commitment to quality, differentiating suppliers in competitive markets.
How to Develop Certified WPS & PQR: A Step-by-Step Guide
Certified WPS and PQR are not just technical documents—they are the backbone of welding quality assurance. Achieving welding excellence through certified procedures requires a systematic approach. Here’s how to implement effective WPS and PQR programs:
Step 1: Comprehensive Requirement Analysis
Technical Review:
- Study customer drawings, specifications, and acceptance criteria in detail
- Identify all welding joints, including those in subassemblies
- Determine base material grades and their weldability characteristics
- Assess thickness ranges and joint configurations
- Evaluate welding positions required (flat, horizontal, vertical, overhead)
Standards Determination:
- Identify all applicable welding standards (EN ISO 15614, AWS D1.1, ASME IX, etc.)
- Understand specific qualification requirements for the application
- Determine if third-party certification is required or preferred
- Check for industry-specific requirements (construction, pressure equipment, offshore, etc.)
Feasibility Assessment:
- Evaluate in-house capabilities against requirements
- Identify any new qualifications needed
- Assess timeline and resource requirements
- Consider material procurement and testing logistics
This upfront analysis prevents costly surprises later and ensures the qualification program addresses all actual production needs.
Step 2: WPS Development
Process Selection: Choose welding processes based on:
- Material type and thickness
- Joint accessibility and position
- Production efficiency requirements
- Available equipment and welder skills
- Quality and cost considerations
Common processes include GMAW (Gas Metal Arc Welding), GTAW (Gas Tungsten Arc Welding), FCAW (Flux-Cored Arc Welding), and SAW (Submerged Arc Welding).
Parameter Design: Establish welding parameters through:
- Engineering calculations based on material properties
- Reference to similar qualified procedures
- Manufacturer recommendations for filler materials
- Heat input calculations to control microstructure
- Consideration of distortion control needs
Critical Variables: Pay special attention to:
- Preheat requirements based on carbon equivalent and thickness
- Interpass temperature limits to control heat-affected zone properties
- Travel speed and heat input ranges
- Shielding gas selection for optimal protection
- Post-weld heat treatment specifications when needed
Documentation: Create clear, complete WPS documents that:
- Follow applicable standard formats (EN ISO 15609, AWS B2.1, etc.)
- Specify all essential and non-essential variables
- Include sketches of joint preparation and welding sequence
- Are unambiguous and directly usable by welders
Many companies engage certified welding engineers for this critical work, ensuring procedures are both technically sound and compliant with standards.
Step 3: Rigorous PQR Testing
Test Weld Production:
- Fabricate test assemblies following the preliminary WPS exactly
- Use production-equivalent materials and conditions
- Monitor and record all actual welding parameters
- Document any deviations or observations
- Ensure proper identification and traceability of test welds
Mechanical Testing: Conduct comprehensive testing to verify weld properties:
- Tensile Testing
- Bend Testing
- Impact Testing
- Hardness Testing
Non-Destructive Testing: Before destructive testing, verify internal soundness through:
- Radiographic Testing (RT) for volumetric defects
- Ultrasonic Testing (UT) for laminations and lack of fusion
- Magnetic Particle Testing (MT) or Liquid Penetrant Testing (PT) for surface defects
Documentation: Record all test data completely:
- Actual welding parameters used (not ranges, but actual values)
- All test results with specimen identifications
- Testing laboratory information
- Test equipment calibration status
- Photographs of test specimens and failures
- Any anomalies or noteworthy observations
Step 4: Third-Party Certification
For European markets and many international applications, third-party certification is essential:
Certification Body Selection: Choose recognised organisations such as:
- TÜV (various divisions: TÜV SÜD, TÜV Rheinland, TÜV NORD)
- Lloyd’s Register
- Bureau Veritas
- DNV (Det Norske Veritas)
- Other notified bodies appropriate for your market
Submission Process:
- Compile complete documentation packages (WPS drafts, PQR data, test reports)
- Submit for review by certified welding inspectors
- Address any questions or requests for additional information
- Arrange witnessed testing if required by the certification body
- Respond to any non-conformances identified during review
Approval: Upon successful review:
- Receive stamped and signed PQR approval
- Obtain final WPS approval based on the qualified PQR
- Maintain certification records in controlled document systems
- Understand validity conditions and any limitations
Although third-party certification involves costs (testing, review fees, possibly witnessed testing) and time (typically several weeks to months), this investment pays dividends through market access, customer confidence, and reduced risk of quality failures.
Step 5: Production Implementation & Control
Welder Qualification:
- Qualify welders according to applicable standards (EN ISO 9606, ASME IX, AWS D1.1)
- Ensure qualifications cover the actual production WPS variables
- Maintain current records of all welder certifications
- Establish requalification schedules (typically every 6 months to 2 years)
Training Programs:
- Train welders on specific WPS requirements before production
- Provide clear, accessible copies of WPS at workstations
- Educate supervisors on critical variables and acceptance criteria
- Ensure welding engineers are available for technical support
Process Controls: Implement systems to ensure WPS compliance:
- Pre-weld checks of material certification and preparation
- Real-time monitoring of critical parameters where possible
- Process control forms documenting preheat, interpass temperature
- Identification systems tracking which WPS applies to each weld
Inspection & Testing: Establish quality verification at appropriate stages:
- Visual inspection according to relevant standards (EN ISO 17637, AWS D1.1)
- Dimensional verification of joint preparation and final welds
- Non-destructive testing per WPS requirements and customer specifications
- Documentation of all inspection results with traceability to specific welds
Corrective Action: When non-conformances occur:
- Investigate root causes promptly
- Determine if issues relate to WPS limitations, welder technique, or other factors
- Implement effective corrective actions
- Consider WPS revisions if procedure limitations are identified
- Document all corrective actions for future reference
Step 6: Continuous Improvement
This quality system doesn’t end with production. The following issues should be addressed continuously:
- Review WPS effectiveness based on production feedback
- Update procedures to incorporate new materials and technologies
- Conduct periodic audits to ensure ongoing compliance
- Respond to customer feedback and changing market requirements
The Business Case for Excellence
Implementing rigorous WPS and PQR programs requires investment in engineering time, testing costs, equipment, and personnel training. Is this investment justified?
Quantifiable Benefits
- Reduced Defect Costs
- Higher Efficiency
- Expanded Market Access
- Lower Risk Exposure
- Reduced Inspection Burden.
Intangible Benefits
- Brand Reputation
- Customer Confidence
- Employee Pride
- Competitive Advantage
Conclusion: The Path to Welding Excellence
In an era of global competition and demanding quality standards, certified WPS and PQR are not optional luxuries—they are foundational requirements for any serious welding fabrication business.
But beyond mere compliance, they represent a philosophy: that quality is designed and proven, not hoped for and inspected in.
The path to welding excellence through certified procedures requires:
- Investment in engineering expertise and testing capabilities
- Discipline in following systematic development processes
- Commitment to implementing procedures rigorously in production
- Continuous improvement to keep procedures current and effective
Companies that embrace this path find themselves not just meeting standards but exceeding customer expectations, accessing premium markets, and building reputations for reliability that generate long-term competitive advantage.
FAQ: Common Questions about WPS & PQR
Q: Does every product require a separate WPS?
A: Not necessarily. Similar materials and welding configurations can often be covered by a single WPS, provided they fall within the qualified range of the supporting PQR. However, significant changes in material grade, thickness, welding position, or process require separate qualification. Our engineering team evaluates each project to determine applicable WPS.
Q: How long is a PQR valid?
A: A PQR typically remains valid indefinitely unless there are significant changes to materials, processes, or applicable standards. The factory with a qualified PQR should regularly review and update its documentation to ensure ongoing compliance with current standards and customer requirements.
Q: Can you provide WPS/PQR documentation to our inspectors?
A: Absolutely. If our clients require, XDL can provide complete WPS/PQR packages to clients and third-party inspectors as standard practice. This documentation is part of our quality assurance commitment and facilitates smooth project approval and inspection processes.
Q: What if our project requires special material combinations not in your current portfolio?
A: XDL can develop and qualify new WPS/PQR for specific project requirements. Our engineering team will work with you to understand your specifications and develop appropriate procedures. We maintain relationships with major certification bodies to expedite the qualification process.
Q: How do you ensure welders follow the WPS during production?
A: Through multiple control mechanisms: comprehensive welder training on specific procedures, verification of welder certifications before assignment, on-site supervision by qualified welding supervisors, regular quality audits throughout production, and inspector verification of welding parameters and techniques.
Q: What is XDL’s response process if initial testing fails during welding procedure qualification?
A: We treat such instances as valuable improvement opportunities. Our structured process includes: First, conducting a comprehensive root cause analysis to determine whether the failure originated from procedural parameters, materials, or execution. Then, revising the draft WPS based on findings and repeating the qualification testing, with all associated costs borne by XDL. Finally, we document these insights in our knowledge management system to prevent recurrence.
Q: Can our quality team participate in or witness the PQR testing process?
A: We actively encourage and welcome client participation. You may assign quality representatives to observe the entire testing process at our partnered laboratories. This transparency not only builds trust but also provides your team with deeper insight into our quality control systems.
Q: For low-volume or prototype projects, is it more economical to use existing WPS?
A: Yes, this is precisely where our system delivers value. In most cases, you won’t need to fund a full qualification for a single project. We first scour our PQR library to identify existing qualifications covering your requirements—significantly reducing both costs and lead times. New qualifications are only necessary when your specifications exceed our current qualified range.
Partner with XDL for Certified Welding Excellence
If your project requires certified welding procedures, strict compliance with international standards, or support in developing new WPS/PQR for special materials, XDL is ready to assist.
Our engineering team, backed by over 10 years of manufacturing experience and a full portfolio of qualified welding procedures, can help you:
- Develop new WPS & PQR tailored to your specifications
- Provide third-party–certified documentation (TÜV, LR, BV, DNV)
- Support multi-standard compliance (ASME, EN, AWS)
- Ensure consistent welding quality across all production batches
- Accelerate project approval, inspection, and onboarding processes
Contact us today to discuss your welding requirements or request a full WPS/PQR documentation package for your next project.
👉 Email: inquiries@xdlmachinery.com
