Difference between WPS and PQR (WPS vs PQR)

difference between WPS and PQR

WPS and PQR are mandatory documents when welding needs to comply with a standard. Both documents are closely related but quite different. The PQR is a standard document, but users may not be from the same background who created it.

Welders or engineers who created the welded product develop a WPS to make the product comply with quality standards. While in the case of PQR, it is always associated with inspectors, manufacturers, or contractors who use this document for testing and verification purposes.

In this article, you will learn about the Welding Process specification (WPS) and Procedure qualification report (PQR), its importance, and the difference between both documents.

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What is Welding Process Specification (WPS)?

A WPS is a document that acts as a guide for the welding work that meets all the applicable code and standard requirements and production standards also. WPS acts like a recipe for welding work just like a recipe for making pancakes. This gives details about all the required ingredients and quantity of what you need for welding work.

This also includes information such as base metal grade, filler metal class, amperage range, shielding gas type and composition, any requirement of pre-heat and interpass temperature. The idea behind WPS is that all welders going to engage in a particular job will follow the details given on WPS so the mechanical properties of each weld will be reasonably the same.

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What is Procedure Qualification Report (PQR)?

A procedure qualification record or PQR is the record of the actual welding test parameters used during welding. PQR is the basic founding document of procedures that are concerned and is used to produce a welding procedure specification sheet for welding production.

PQR is a company-dependent document and it never expires. The document of PQR gives details of the suitability of weld for required mechanical properties, for example, Strength and ductility.

Note: Please note the procedure qualification record cannot be revised otherwise the case for revising is typing error or misspelling.

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Importance of WPS and PQR

WPS and PQR are like blueprints for creating weld joints repeatably, Efficiently, and in a safe manner. This document provides an approximate breakdown detail of the topic that needs to be covered for testing. The importance of WPS and PQR can be as follows:

  1. Provide and focuses on details on practical application and inspection.
  2. Give details of conducting welder qualification test.
  3. Give welding parameter to be checked for quality weld joints.

Difference between WPS and PQR

Yet both documents are somewhat the same but there are some major differences between WPS and PQR as follows:

  1. WPS serve as blueprint of written instruction on how to weld products. while PQR is a document that whether the standard is being followed by inspection.
  2. In WPS, the welding parameters are explained in the context of instruction. On the other hand, PQR uses the parameters as a checklist to check if it meet standard or not.
  3. WPS is generally associated with welders and engineers who create welded products while PQR associated with inspectors, manufacturers and contractors who use the documents for testing.
  4. Another difference is related to document contents. Where WPS is filled with many texts, images and instruction guides. PQR is like a checklist with blank spaces and written notes that need to filled by during the inspection.
  5. WPS is a document for welders before during and after the testing while PQR is a document for concerned engineers, inspectors and contractors.

In simple terms:

  • The WPS is written from the PQR.
  • A PQR comes before a WPS.
  • A PQR is needed to do a WPS.
  • The PQR is specific while the WPS is generic.
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