In this article, you will learn the difference between prequalified welding procedures and AWS B2.1 Standard Welding Procedures (SWPS), and when to use each.
When working with welding codes and standards, one of the most misunderstood topics is the difference between:
- Prequalified Welding Procedure Specifications (WPS)
- AWS B2.1 Standard Welding Procedures (SWPS)
At first glance, they seem similar. Both are “pre-approved” in some sense, and both can save time and cost by avoiding full procedure qualification testing.
But they are not the same thing—and using the wrong one (or misunderstanding them) can lead to compliance issues, rejected work, or failed inspections.
Let’s break it down clearly.
What Is a Prequalified Welding Procedure (WPS)?
A prequalified WPS is allowed by a specific welding code, such as AWS D1.1, without requiring procedure qualification testing, as long as all code conditions are strictly followed.
These procedures are based on proven industry practices and are limited to specific materials, joint designs, and welding variables defined in the code.
Why It Exists
Codes like AWS D1.1 include prequalified procedures because:
- They are based on proven industry practices
- They reduce the need for redundant testing
- They allow faster project startup
Key Requirements for Prequalified WPS
To use a prequalified WPS, you must strictly follow the code’s rules, including:
- Prequalified base metals (listed in the code)
- Specific joint designs
- Qualified filler metals
- Allowed welding processes
- Required preheat and interpass temperatures
- and there may be other requirements, depending on the standard
If you deviate from any of these requirements, the procedure is no longer prequalified, which means you must perform full qualification testing.
Important Point
A prequalified WPS is not a generic document you download and use blindly. It must still be written by your company, reviewed, and applied correctly for your specific project.
What Is an AWS B2.1 Standard Welding Procedure (SWPS)?
An AWS B2.1 SWPS is a standardized welding procedure published by AWS. These procedures are supported by Procedure Qualification Records (PQRs) submitted by industry and reviewed and approved by the AWS B2 Committee.
You can purchase SWPS documents directly from AWS and use them within the limits defined in the document.
What You Still Need to Do
- Verify that SWPSs are accepted by the governing code
- Ensure they meet project specifications
- Confirm they apply to your materials, thickness, and process
Key Differences
Prequalified WPS are defined directly within welding codes and require strict adherence to code rules.
SWPS are pre-tested procedures with documented supporting data, available for purchase on the AWS website.
- Prequalified WPS: No purchase required, but requires expertise to develop and prepare in writing
- SWPS: Must be purchased, but saves development time
When Should You Use Each?
Use a Prequalified WPS When:
- You are working under codes that allow pre qualification welding procedures, like AWS D1.1, AWS D1.3, AWS D1.6, etc.
- Your materials and joint designs fall within prequalified limits
- You have the expertise to properly develop and control the procedure
Use an AWS B2.1 SWPS When:
- You want a ready-to-use, tested procedure
- You don’t want to perform your own PQR testing
- Your project or standard allows or accepts SWPS usage
Common Mistakes to Avoid
❌ Assuming Prequalified Means “following the code”
Prequalified WPS must be written and often submitted for approval to the engineer of record or inspector of record.
❌ Using SWPS Without Code Approval
Not all codes or engineers automatically accept SWPS. Often, engineering approval is required and you may also be required to perform an adoption test.
❌ Ignoring Project Specifications
Even if something is allowed by a specific welding standard, the Engineer of Record may require additional qualification.
Due diligence
Even when using SWPS: – Confirm they are permitted by the governing code – Ensure they meet project specifications and engineer requirements – Verify applicability to your materials, thickness, and process.
In some cases, the governing welding standard may still require a test to adopt the SWPS. This is not a full PQR, but a verification step, saving time and cost compared to full qualification.
Final Takeaway
Both prequalified WPS and AWS B2.1 Standard Welding Procedures (SWPS) are designed to simplify welding procedure qualification—but they do it in different ways.
- Prequalified WPS relies on code-defined rules and limitations
- SWPS relies on pre-tested procedures approved by the AWS B2 Committee.
Neither replaces the need for:
- Proper review
- Code compliance
- Alignment with project specifications
Understanding the difference isn’t just technical knowledge—it’s what keeps your work accepted, compliant, and moving forward.
Continue Learning
To better understand how procedures fit into the bigger picture:
Need Help With WPSs for your upcoming project?
- Review our prequalified WPSs page, where you can purchase prequalified WPSs per various welding codes
- Watch our training video on how to write prequalified WPSs in accordance with AWS D1.1
- contact us
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Our WPSs are prepared by AWS Senior Certified Welding Inspectors and/or AWS Certified Welding Engineer.