what must be done when a nonessential variable on a wps is changed?

What must be done when a nonessential variable on a WPS is changed?

⭐ Short Answer “When a nonessential variable on a WPS is changed, the WPS must be revised or updated, but requalification is NOT required.“

When a nonessential variable on a Welding Procedure Specification (WPS) is changed, it is necessary to revise the WPS to accurately reflect the modifications.

🧩 What Exactly Is a Nonessential Variable?

Under ASME Section IX (and similarly in AWS codes), welding variables are grouped into three categories:

Essential variables – Affect mechanical properties. Change them, and you must requalify the procedure.
Supplementary essential variables – Kick in when notch toughness is required.

Nonessential variables – Do not affect mechanical properties but still influence how the weld is made.

Nonessential variables cover things like:

Cleaning methods
Backing removal
Travel speed
Weave vs. stringer technique
Joint details that don’t affect qualification ranges

They don’t change the weld’s mechanical performance, but they do change how the welder performs the work.

🛠️ So What Must You Do When a Nonessential Variable Changes?

Here’s the key point:

Changing a nonessential variable requires updating the WPS—but it does not require requalification.

That means:

✔️ You must revise the WPS.

The document must reflect the new value so welders have accurate instructions.

✔️ You must control the revision.

Codes require traceability—revision numbers, dates, and notes about what changed.

❌ You do NOT need a new PQR.

No coupons, no bend tests, no tensile tests. The original qualification still stands.

📋 Why This Matters in Real‑World Welding Shops

Even though nonessential variables don’t affect weld integrity, they absolutely affect:

Consistency
Repeatability
Welder clarity
Audit readiness

A WPS is a controlled document. If production welders are using outdated instructions, you’re opening the door to:

NCRs
Audit findings
Customer complaints
Confusion on the shop floor

Updating the WPS keeps everyone aligned and protects your quality system.

🧠 Practical Steps Most QC Managers Follow

Here’s what happens in a well‑run shop:

Identify the nonessential variable change.
Update the WPS with the new value.
Increment the revision number and date.
Add a brief revision note.
Reissue the WPS to production.
Archive the old version per your document control procedure.

Simple, clean, and code‑compliant.

🔚 Final Thoughts

Nonessential variables may not affect the weld’s mechanical properties, but they absolutely matter for documentation, consistency, and compliance. The rule is simple:

Change the variable → Update the WPS → No requalification needed.

While requalification of the welding procedure is not typically required for nonessential variables, updating the WPS is essential for maintaining proper documentation and ensuring compliance with applicable standards.

“If non-essential variable changes, Revise your WPS and include the previous PQR number for accurate documentation.”

In simpler terms, if you have a Welding Procedure Specification (WPS) and need to use it for a different job but want to change some nonessential variables, you don’t have to re-qualify the WPS.

For instance, if you have a WPS for TIG Welding with a V groove joint design and want to use it for a job with a U groove joint design, you can revise the WPS by including the previous Procedure Qualification Record (PQR).

This change is considered nonessential and doesn’t require requalification or additional mechanical property tests since it doesn’t affect the welding’s mechanical properties.

🔍 What the Codes Actually Say

✅ Nonessential variables

Defined as variables that do not affect the mechanical properties of the weld.
Because they don’t impact weld integrity, changing them does NOT require a new PQR (Procedure Qualification Record).
However, the WPS must be updated to reflect the new value so welders have correct instructions.

Examples of nonessential variables (depending on code):

Travel speed
Backing removal method
Cleaning method
Technique details (weave vs. stringer, etc.)
Joint details that do not affect qualification ranges

Here are the steps to follow:

Identify the Nonessential Variable

Determine which nonessential variable(s) has been changed. Nonessential variables are those that can be modified without necessitating requalification of the welding procedure.

Document the Change

Clearly document the specific changes made to the nonessential variable(s) in the WPS. This includes updating any parameters or details that have been modified.

Revise the WPS

Update the WPS to reflect the changes accurately. This involves making the necessary modifications to the affected sections or tables within the document.

Maintain Documentation

Keep a record of the changes made to the WPS, including the date of revision and the reason for the modification. This documentation ensures traceability and provides a clear history of the WPS changes.

Communicate the Revised WPS

Distribute the revised WPS to the relevant stakeholders, including welding personnel, inspectors, and other individuals who require access to the updated information. Ensure that everyone involved is aware of the changes.

Follow Established Procedures

Adhere to any internal procedures or protocols related to WPS revisions. This may involve obtaining approval from a designated authority or following specific documentation control processes within your organization.

By revising the WPS to reflect the changes made to the nonessential variable(s), you maintain accurate and up-to-date documentation of the welding procedure. This promotes consistency, compliance, and clarity in the execution of welding activities.

📊 Essential vs. Nonessential Variables — Comparison Table

Essential vs. Nonessential Variables

Category	Essential Variables	Nonessential Variables
Impact on Mechanical Props	Yes – affects weld strength/toughness	No – does not affect mechanical properties
Requalification Required	Yes – new PQR needed	No – update WPS only
Examples	P-Number change, filler metal change, process change	Travel speed, cleaning method, technique (weave/stringer)
Documentation Requirement	Update WPS + new PQR	Update WPS (revision control)
Risk if Not Updated	High – weld may fail code requirements	Moderate – inconsistent welding instructions
Code Basis	ASME IX Essential/Supplementary Essential	ASME IX Nonessential
Shop Impact	Testing, cost, engineering review	Quick administrative update

📝 WPS Revision Checklist (When a Nonessential Variable Changes)

✔️ 1. Identify the Change

Determine which nonessential variable is being modified
Confirm it does not trigger essential or supplementary essential requirements

✔️ 2. Update the WPS

Edit the specific field (e.g., technique, travel speed, cleaning method)

Ensure formatting and terminology match your company’s standard

✔️ 3. Apply Revision Control

Increment revision number
Update revision date
Add a brief revision note (e.g., “Updated cleaning method from wire brush to power brush”)

✔️ 4. Review and Approve

QC/Engineering signs off per your document control procedure
Ensure the change aligns with customer or project requirements

✔️ 5. Reissue the WPS

Provide updated WPS to welders and supervisors
Replace old versions in:

Shop floor binders
Digital document systems
Welder tablets or kiosks
Job packets

✔️ 6. Archive the Previous Version

Store old WPS in controlled archive
Maintain traceability for audits and customer reviews

POCKET REFERENCE CARD — WPS NONESSENTIAL VARIABLE CHANGES

For Inspectors / QC / Welding Supervisors

WHAT IS A NONESSENTIAL VARIABLE?

A welding variable that does NOT affect mechanical properties.
Changing it does NOT require requalification (no new PQR).
Still must be documented on the WPS.

WHEN A NONESSENTIAL VARIABLE CHANGES:

VERIFY THE CHANGE

Confirm the variable is nonessential per ASME IX or AWS code.
Ensure no essential or supplementary essential variables are affected.

UPDATE THE WPS

Modify the specific value (technique, travel speed, cleaning method, etc.).

Keep formatting consistent with your WPS template.

APPLY REVISION CONTROL

Increase revision number.
Update revision date.
Add a brief revision note describing the change.

APPROVAL

QC/Engineering signs off per document control procedure.

ISSUE THE UPDATED WPS

Replace old versions in shop binders, digital systems, and job packets.
Notify welders and supervisors of the new revision.

ARCHIVE OLD VERSION

Store previous WPS revision in controlled archive.
Maintain traceability for audits and customer reviews.

QUICK IDENTIFICATION GUIDE

ESSENTIAL VARIABLES:

Affect mechanical properties.
Changing them requires new PQR. NONESSENTIAL VARIABLES:
Do NOT affect mechanical properties.
Changing them requires WPS update ONLY.

COMMON NONESSENTIAL VARIABLES (Examples)

Travel speed
Cleaning method
Backing removal method
Weave vs. stringer technique
Joint details not affecting qualification ranges

INSPECTOR REMINDER

If the variable does not change the qualification range,

it is NONESSENTIAL — update the WPS, revise, reissue, archive.

Welding Variables- Essential variable, Non- Essential Variables & Supplementary Essential Variables

Sandeep Kumar- Welding & NDT Expert

Sandeep Kumar

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