What is a PQR and a WPS?

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Procedure Qualification Record (PQR)

A Procedure Qualification Record (PQR) is the supporting document that verifies and qualifies the WPS through actual testing. It records the precise details of a test weld (called a “procedure qualification coupon”) performed under controlled conditions, along with the results of destructive and non-destructive tests to prove the weld’s integrity. The PQR acts as evidence that the welding procedure outlined in the WPS can produce sound, reliable welds that comply with applicable codes.

Key aspects of a PQR:

  • Actual weld data: Exact values used during the test weld, such as measured amps, voltage, travel speed, and gas flow, which are narrower than the ranges in a WPS.
  • Test results: Documentation of inspections like tensile strength tests, bend tests, radiography, or ultrasonic testing to confirm the weld meets mechanical properties (e.g., no cracks, adequate toughness).
  • Variables and observations: All essential, supplementary, and nonessential variables from the test, plus any deviations or notes.
  • Certification: Signed by the manufacturer or inspector, confirming the test met standards.

A single PQR can support multiple WPSs, but a WPS must always be backed by at least one qualifying PQR. The PQR is created first through testing, and it never expires, though it must align with current codes.

Welding Procedure Specification (WPS)

A Welding Procedure Specification (WPS) is a formal, written document that provides detailed instructions for welders to consistently produce high-quality welds that meet specific code requirements, such as those from NZ Standards like AS/NZS 2980:2007 and ISO 9606-1 or the American Welding Society (AWS) or ASME standards. Think of it as a “blueprint” or recipe for welding: it outlines the exact steps, parameters, and materials to use for a particular welding job. This ensures repeatability, safety, and compliance, reducing the risk of defects or rework.

Key elements typically included in a WPS:

  • Welding process: E.g., Shielded Metal Arc Welding (SMAW), Manual Metal Arc Welding (MMAW), Gas Metal Arc Welding (GMAW), or Gas Tungsten Arc Welding (GTAW).
  • Base materials and filler metals: Types of metals being joined and the consumables used.
  • Joint design: Geometry, preparation (e.g., bevel angles), and fit-up.
  • Welding positions: Flat, horizontal, vertical, etc.
  • Parameters and variables: Essential ranges for things like current (amps), voltage, travel speed, preheat temperatures, shielding gas flow rates, and electrode sizes. These are “essential variables” that, if exceeded, may require requalification.
  • Post-weld treatments: Any heat treatment, cleaning, or inspection steps.

WPSs are company-specific and must be qualified before use in production. They don’t expire but should be reviewed periodically for updates. Without a proper WPS, welds may not meet industry standards, potentially leading to failures in critical applications like pressure vessels or pipelines.

How WPS and PQR Work Together?

The relationship is sequential and interdependent:

  1. Development: Start with a preliminary WPS (pWPS) based on engineering needs.
  2. Qualification: Weld a test plate using those parameters and document everything in the PQR, including test results.
  3. Finalization: If the PQR passes, generate the official WPS with allowable ranges derived from the PQR’s data.
  4. Production Use: Welders follow the WPS, and the PQR serves as proof for auditors or clients.

This system ensures welds are consistent and safe, especially in regulated industries.