How to Review WPS, PQR and Welder Qualification Documents

Why Document Review Matters

Welding is a critical process in the fabrication of pipe fittings, flanges, and other pressure-containing components. The integrity of a welded joint depends not only on the skill of the welder but also on the correctness of the welding procedure. Three documents govern this: the Welding Procedure Specification (WPS), the Procedure Qualification Record (PQR), and the welder qualification certificate. For EPC engineers and procurement managers, reviewing these documents is essential to ensure that the manufacturer's welding is qualified for the intended service.

A WPS provides the production welding instructions, including parameters such as process, filler metal, preheat, interpass temperature, and post-weld heat treatment. A supporting PQR documents the results of the procedure test and defines the qualified range. A welder certificate demonstrates that an individual welder is qualified within a defined range. It is important to note that a welder certificate cannot replace the procedure qualification; both are required.

Key Standards: ISO 15614-1 and ISO 9606-1

Two international standards are commonly referenced for welding qualification:

• ISO 15614-1 covers welding-procedure qualification by procedure test. It specifies how to qualify a WPS by testing a test piece to verify that the proposed welding procedure produces sound joints.
• ISO 9606-1 covers qualification testing of welders for fusion welding of steels. It defines the test methods, ranges of qualification, and validity periods for welder certificates.

These standards are widely used in Europe and many other regions. However, other codes such as ASME Section IX are also common, especially for projects in North America or those following ASME pressure vessel and piping codes. The contract or project specification will dictate which standard applies.

What to Check in a WPS

When reviewing a WPS, verify that it includes all essential variables required by the applicable standard. For ISO 15614-1, these include:

• Welding process (e.g., 111, 141, 135)
• Joint design and preparation
• Base material group and thickness range
• Filler metal classification and diameter
• Welding position(s)
• Electrical characteristics (current, voltage, polarity)
• Welding speed or travel speed
• Preheat and interpass temperatures
• Post-weld heat treatment (if any)
• Shielding gas and flow rates

Check that the WPS is consistent with the PQR. The PQR should record the actual parameters used during the procedure test, and the WPS must be within the qualified ranges. For example, if the PQR was made on a 10 mm thick plate, the WPS may only qualify for thicknesses within the range specified by the standard (e.g., 5 mm to 20 mm for ISO 15614-1).

Reviewing the PQR

The PQR is the evidence that the welding procedure was tested and found acceptable. It should include:

• The test piece details (material, thickness, diameter)
• The actual welding parameters used
• The results of non-destructive and destructive tests (e.g., tensile, bend, impact, hardness)
• The name of the testing laboratory and the date of testing
• The standard and acceptance criteria used

Ensure that the PQR is signed and dated by the responsible parties. Check that the test results meet the acceptance criteria of the applicable standard. For example, ISO 15614-1 specifies minimum tensile strength and bend test requirements. If impact testing is required, the absorbed energy must meet the specified values at the test temperature.

Welder Qualification Certificates

A welder certificate proves that an individual welder has demonstrated the skill to produce sound welds within a defined range. When reviewing a welder certificate, check:

• The welder's name and identification number
• The welding process and positions qualified
• The material group and thickness range
• The standard used (e.g., ISO 9606-1)
• The date of the test and the validity period
• The signature of the examiner or authorized body

ISO 9606-1 specifies that a welder certificate is valid for a period of two years, provided the welder is continuously employed in welding or the employer provides evidence of continuity. After two years, the certificate can be extended if the welder has been welding in the qualified range. After six months of interruption, the qualification is no longer valid.

Common Pitfalls and Risks

One common mistake is to assume that a document is valid simply because it has a title. Always cross-check the details. For example, a WPS may be qualified for a certain material group, but the PQR may have been made on a different material group. Similarly, a welder certificate may be for a different process or position than what is required for the job.

Another risk is mixing ISO and ASME Section IX qualification ranges. These standards have different essential variables and range extensions. Unless the contract explicitly accepts both, you should not assume that a qualification under one standard is valid under the other. Always verify which standard is applicable.

Also, be aware that a welder certificate does not qualify a procedure. Even if a welder is highly skilled, the welding procedure must still be qualified separately. Conversely, a qualified procedure does not mean that any welder can use it; each welder must be individually qualified.

Procurement and Inspection Checklist

When sourcing pipe fittings or flanges that require welding, include the following in your RFQ and inspection plan:

• Specify the applicable welding standards (e.g., ISO 15614-1 and ISO 9606-1, or ASME Section IX).
• Request copies of the WPS, PQR, and welder certificates for review before production.
• Verify that the manufacturer's welders are qualified for the specific processes and positions required.
• During inspection, confirm that the welding parameters used in production match the WPS.
• Check that the welder's certificate is valid and covers the work being performed.
• If the project requires third-party inspection, ensure that the inspector reviews these documents.

Conclusion

Reviewing WPS, PQR, and welder qualification documents is a critical step in ensuring the quality and safety of welded components. By understanding the key standards and knowing what to check, you can avoid costly errors and ensure that your piping systems are fabricated to the required quality. For more information on pipe fittings and flanges, visit our products page or contact us for assistance.

Sources

• https://www.iso.org/standard/51792.html
• https://www.iso.org/standard/54936.html
• https://www.twi-global.com/technical-knowledge/job-knowledge/welding-procedure-039
• https://www.twi-global.com/technical-knowledge/faqs/faq-what-constitutes-acceptable-welder-qualification