Can I use a FCAW-G WPS to cover FCAW-S production welding?

No. AWS D1.1:2025 Table 6.6 treats gas-shielded and self-shielded FCAW as separate processes. A WPS qualified with FCAW-G does not cover FCAW-S work — you need a separately qualified PQR and WPS for each process.

Is shielding gas an essential variable for FCAW-S?

No. There is no shielding gas variable for FCAW-S because the shielding atmosphere is generated by the electrode flux itself. For FCAW-G, gas composition and flow rate are essential variables — any change outside the qualified range requires requalification.

Does FCAW-S require a PQR, or can it use a prequalified WPS?

FCAW-S is not eligible for prequalified WPS status under AWS D1.1:2025. Every FCAW-S procedure must be backed by test welds and a signed PQR. FCAW-G (gas-shielded) can qualify for prequalified status under Clause 5 when all prequalified conditions are met.

What electrode change triggers requalification under FCAW-G Table 6.6?

Changing the filler metal F-number or AWS classification — for example, from E71T-1C to a different classification family — is an essential variable. A change in shielding gas composition outside the qualified mixture also triggers requalification.

FCAW-S vs FCAW-G: WPS essential variables for structural welding

FCAW-S and FCAW-G are separate processes under AWS D1.1:2025. Switching triggers full requalification — here's which essential variables apply to each process.

Fab shops running both self-shielded and gas-shielded FCAW often assume the two processes are interchangeable from a WPS standpoint. They are not. AWS D1.1:2025 treats FCAW-S and FCAW-G as distinct processes, each with its own column in Table 6.6, the essential-variables table for PQR qualification. Using a FCAW-G WPS to cover FCAW-S production welds is an unsupported procedure — a finding that will surface in any AISC or owner QC audit.

What Makes FCAW-S and FCAW-G Different

Self-shielded FCAW (FCAW-S) generates its shielding atmosphere entirely from flux compounds burned off inside the electrode core. No external gas cylinder or flow meter is required. Common structural FCAW-S electrodes include E71T-8 and E71T-11, both classified under AWS A5.20.

Gas-shielded FCAW (FCAW-G) uses an externally supplied shielding gas — typically 75/25 Ar/CO₂ or 100% CO₂ — in addition to the flux in the electrode core. The gas protects the arc and weld pool; the flux handles deoxidation and slag formation. E71T-1C and E71T-9M are common structural choices for FCAW-G, both also under AWS A5.20.

The deposited weld metal properties differ between the two processes. FCAW-S is sensitive to travel speed, electrode extension (stickout), and ambient conditions in ways distinct from FCAW-G. That difference in behavior is why the code requires separate qualification rather than allowing one PQR to cover both.

Table 6.6 Process Columns

AWS D1.1:2025 Table 6.6 lists essential variables for SMAW, SAW, GMAW, FCAW, and GTAW. Within the FCAW grouping, the table distinguishes FCAW-G and FCAW-S as separate columns. A PQR produced with FCAW-G qualifies the FCAW-G column only. You cannot extend that coverage to FCAW-S work without a separate test weld under FCAW-S conditions.

The essential variables that apply to each process genuinely differ:

Variables specific to FCAW-G:

Shielding gas type and composition (e.g., 75/25 Ar/CO₂ vs. 100% CO₂)
Shielding gas flow rate range
Transfer mode, where applicable

Variables specific to FCAW-S:

Contact-tip-to-work distance (stickout range) — changes in stickout affect flux burnoff rate and shielding effectiveness, making it an essential variable unique to the self-shielded process
Electrical characteristics tied to the self-shielding mechanism

Variables common to both FCAW-G and FCAW-S:

Filler metal F-number and classification
Current type and polarity (DCEP vs. DCEN)
Wire diameter change beyond one standard size
Addition or deletion of preheat or PWHT
Welding position (qualifying flat does not cover vertical without the appropriate test)
Base metal group per Table 6.9
Joint design category (groove vs. fillet, backing type)

Rule library based on AWS D1.1:2025; verify against your governing edition.

For a full breakdown of which variables are essential vs. nonessential and why the distinction matters, see WPS essential variables vs. nonessential variables.

Prequalified WPS Eligibility

One of the most practical differences between the two process types is prequalified WPS status. Under AWS D1.1:2025, a prequalified WPS allows you to write a procedure without conducting test welds — provided the process, joint geometry, base metal, and electrode all meet Clause 5 conditions. FCAW-G can achieve prequalified status when those conditions are satisfied.

FCAW-S is not eligible for prequalified WPS status under AWS D1.1:2025. Every FCAW-S procedure requires test welds and a signed PQR. This catches shops that pull an old FCAW-S document from the file cabinet and assume it qualifies as prequalified because it has always worked in the field.

For a full overview of what prequalified status covers and where its limits are, see prequalified WPS under AWS D1.1 Clause 5.

Electrode Changes That Trigger Requalification

For FCAW-G:

F-number change. AWS A5.20 FCAW-G carbon steel electrodes are generally F-number 6. Moving to a low-alloy electrode with a different F-number triggers requalification.
Classification change within F-number 6. Moving from E71T-1C (100% CO₂ shielded) to E71T-1M (mixed gas) is not automatically covered even if both are F-6. If the PQR was run with one gas mixture, production welding with a materially different mixture requires review against the qualified essential variable range.
Shielding gas change. Changing from 75/25 Ar/CO₂ to 100% CO₂ changes the gas composition, which is an essential variable. Document the as-qualified gas mixture on both the PQR and WPS. See shielding gas documentation on a WPS for the specific fields to fill out.

For FCAW-S:

Classification change. E71T-8 and E71T-11 are both FCAW-S structural electrodes but are separate AWS A5.20 classifications with different mechanical properties. Changing classification triggers requalification.
Stickout range change. If the WPS specifies a stickout of ¾–1 in and field conditions push welders to 1½ in or more, that is outside the qualified range. The changed stickout must be addressed either by requalification or by bringing field practice back within the documented range.

Polarity: A Process-Level Gotcha

FCAW-S electrodes — E71T-8 and E71T-11 in particular — run on DCEN (straight polarity). Most other structural processes run DCEP. Polarity is an essential variable under Table 6.6.

A WPS written for FCAW-G with DCEP and then used in the field with an FCAW-S electrode on DCEN represents two simultaneous essential variable violations: wrong process and wrong polarity. Field supervisors who allow this situation create audit exposure that is very difficult to walk back once the welder certification records are compared against the WPS.

Running Both Processes in the Same Shop

Many fab shops run both processes. FCAW-S handles outdoor work and windy conditions where external shielding gas would be blown away; FCAW-G delivers cleaner deposits and better mechanical properties for indoor shop welds. Maintaining both is operationally sensible.

The right approach is two separately qualified procedures:

A FCAW-G WPS backed by a FCAW-G PQR
A FCAW-S WPS backed by a FCAW-S PQR

Both must cover the same base metal groups, thickness ranges, and positions your work demands. Attempting to write a single WPS that claims coverage for both processes using one PQR is not supported — the process-column structure of Table 6.6 requires separate documentation.

For guidance on how thickness range and position qualification interact with WPS scope, see WPS qualification range for thickness and position.

Drafting the WPS: What to Document Differently

When writing a FCAW-G WPS, document:

Shielding gas type, exact composition percentage, and flow rate range (CFH or L/min)
Electrode classification, diameter, and heat input range
Transfer mode if the process operates in a mode where it is relevant

When writing an FCAW-S WPS, document:

Contact-tip-to-work distance (stickout) range — this is process-essential
Electrode classification and diameter
No gas parameters (the field for shielding gas should be marked "N/A" or "Self-shielded")
Heat input range

A WPS software platform that enforces process-column logic — refusing to apply FCAW-G gas fields to an FCAW-S form — catches these errors at draft time rather than at inspection. If you're managing multiple processes and want that validation built in, see our WPS platform.

Common Audit Findings

When a CWI audits FCAW-related WPS packages, these are the most frequent nonconformances:

Single WPS covering both FCAW-G and FCAW-S — valid only if two separate test welds are documented and the WPS clearly segregates process-specific conditions for each.
Gas parameters listed on an FCAW-S WPS — signals that the author copied a FCAW-G document and did not remove gas fields. Auditors treat this as an indicator that other fields may also be inaccurate.
Missing stickout range on an FCAW-S WPS — an essential variable whose omission makes the WPS incomplete.
Electrode classification on production welds does not match the WPS — common when shops update their electrode supply mid-project without re-checking the Table 6.6 essential variable bracket.

Summary

FCAW-S and FCAW-G are not interchangeable under AWS D1.1:2025. Table 6.6 assigns each its own process column, the shielding mechanism differs fundamentally, and FCAW-S requires a PQR where FCAW-G can achieve prequalified status. Maintain separate WPS documents for each process, ensure each is backed by a supporting PQR, and verify that polarity, stickout, electrode classification, and — for gas-shielded work — gas mixture are all within the qualified range before production begins.