What is Welding Procedure Qualification (WPQR)?

In the industrial and construction sectors, metal materials are commonly joined through welding. Welding is a critical production process in terms of both safety and durability. Therefore, the correctness and reliability of the welding process must be documented and verified according to national and international standards. This is where Welding Procedure Qualification, also known as WPQR (Welding Procedure Qualification Record), comes into play.

WPQR is an official document that certifies a welding procedure has been performed in accordance with a specific welding specification and meets the required quality standards. This approval is indispensable for both quality management and legal compliance.

Definition and Importance of WPQR

WPQR (Welding Procedure Qualification Record) is an official document that validates a welding procedure through mechanical testing and confirms its suitability. This certificate demonstrates the adequacy of the welding process carried out according to a specific Welding Procedure Specification (WPS).

The WPQR document tests the technical suitability of the welding method and parameters used, not the welder. Therefore, it should not be confused with WPQ (Welder Performance Qualification), which certifies the operator.

Why is WPQR Required?

The WPQR certificate is important for the following reasons:

1. Quality Assurance: Proves that the welded joint is mechanically and structurally reliable.

2. Legal Compliance: Mandatory to demonstrate compliance with international standards (EN, ISO, ASME, AWS, etc.).

3. Project Safety: Ensures welding quality in industrial projects, especially for pressure vessels, pipelines, bridges, ships, and similar structures.

4. Traceability: Welding parameters are recorded, allowing root cause analysis in case of defects.

5. Tender and Inspection Requirements: WPQR is often required in large-scale projects and is essential for third-party inspections.

WPQR Preparation Process

The preparation of a WPQR certificate follows specific steps, summarized as follows:

1. Preparation of Welding Procedure (PQR Test Weld)

Test welds are prepared according to a specific WPS. These welds are carried out on a pipe or plate based on defined parameters. During welding, all parameters must be recorded: current, voltage, welding speed, welding method, preheating temperature, etc.

2. Sampling of Test Specimens

After completing the test weld, samples are taken from the joints. These specimens undergo destructive and non-destructive testing.

3. Destructive and Non-Destructive Tests

Common tests include:

• Visual Examination (VT)

• Radiographic or Ultrasonic Testing (RT/UT)

• Macro/Micro Section Analysis

• Tensile Test

• Bend Test

• Hardness Test

• Charpy V-Notch Impact Test

These tests assess whether the weld and the heat-affected zone have adequate strength and uniformity.

4. Certification and Reporting

After successful testing, all results are documented in the WPQR certificate. This document is formally approved by an independent certification body or authorized engineer.

Relationship Between WPQR and WPS

WPQR and WPS are complementary documents:

• WPS (Welding Procedure Specification): Specifies welding parameters, joint types, material properties, welding direction, heat input, etc.

• WPQR (Welding Procedure Qualification Record): Confirms that the WPS has been applied in practice and that the procedure is successful.

In short: WPS is the plan, WPQR is the record proving the plan was successfully implemented.

Standards for WPQR Preparation

The standards applied in WPQR preparation vary depending on the industry. The most commonly used standards are:

• EN ISO 15614 (European Standard): Approval of welding procedures for metallic materials.

• ASME Section IX (American Standard): Welding procedure approval for pressure vessels and piping systems.

• AWS D1.1 (American Welding Society): Welding standards for structural steel.

Each standard classifies according to welding type (TIG, MIG, MAG, SMAW), material group, thickness, diameter, welding position, and other variables.

Validity and Scope

The validity of a WPQR certificate depends on the standard used. Generally:

• If the same welding method is applied periodically (e.g., every 6 months), the WPQR remains valid.

• If significant changes are made to welding parameters, a new WPQR may be required.

Additionally, a WPQR certificate is valid only for the combination of materials and parameters used in testing. For different material groups or thicknesses, additional WPQR tests are required.

Who Can Prepare and Approve WPQR?

WPQR tests are usually conducted by the following experts and organizations:

• Welding Engineers

• Third-Party Inspection Bodies (TÜV, Lloyd’s Register, Bureau Veritas, etc.)

• Accredited Laboratories

• Manufacturer’s Quality Department

For official validity, the WPQR must be signed by an authorized engineer or an independent inspection body.

Welding Procedure Qualification (WPQR) is a cornerstone of quality assurance in welded manufacturing processes. It is crucial from both engineering and legal perspectives. WPQR proves that a welding method meets established criteria, ensuring safety, quality, and compliance in production.

Whether operating a small workshop or managing a large energy plant project, performing welding without a WPQR certificate carries serious risks. Therefore, planning and documenting welding processes from the outset is essential for both technical and commercial success.