Combining SMAW root passes with FCAW-G fill and cap is one of the most productive dual-process procedures a structural fabricator can run. SMAW gives you precision at the root — critical on open-root CJP groove welds — while FCAW-G delivers the deposition rates that keep your production schedule moving for fill and cap. The quality management challenge: combining two processes on one WPS means tracking two separate sets of essential variables and writing a PQR that legitimately covers both.
Why Shops Use This Combination
On CJP groove joints — T-joints, butt joints with backing removed, column splice connections — the root pass sets the foundation for everything above it. SMAW, typically E7018 low-hydrogen electrodes, is favored for roots for several practical reasons:
- The covered electrode handles drafts and wind better than gas-shielded processes
- The welder controls arc length by feel, without worrying about maintaining an exact CTWD
- Smaller electrode diameters (3/32" or 1/8") fit tight root openings and restricted access situations
Once the root is deposited and cleared by your CWI, switching to FCAW-G — commonly E71T-1C-H8 or E71T-12C-H8 wire — cuts welding time dramatically. FCAW-G deposition rates run three to five times higher than SMAW for equivalent weld volume, which is significant on heavy structural connections.
Two Processes, Two Sets of Essential Variables
This is where dual-process WPS management gets complex. Under AWS D1.1:2025, Table 6.6 governs essential variables for each welding process. A dual-process WPS operates under both sets simultaneously — a change that would require requalification for either process requires a new PQR for that process.
SMAW root essential variables (Table 6.6):
- Electrode AWS classification (E7018-H4 must stay E7018-H4 — switching to E7018-1-H4 is a classification change)
- Hydrogen designator (-H4, -H8, -H16 are distinct; a change requires requalification)
- Current type and polarity (DCEP is standard for E7018)
- Preheat and interpass temperature limits
- Qualified positions
FCAW-G fill/cap essential variables (Table 6.6), additional to the above:
- Wire electrode AWS classification and designation
- Shielding gas composition and flow rate (75/25 Ar/CO₂ vs. straight CO₂ is an essential variable change)
- Wire diameter (0.045" to 0.052" is a change requiring requalification)
- Electrode extension (CTWD) range
- A5.36 designator rules as revised in the 2025 edition (Table 6.6 Row 8)
Your FCAW-G electrode supplier switching you from E71T-1C-H8 to E71T-12C-H8 — that is a classification change. Either your existing PQR must have tested that exact designation, or you need a new PQR. See the FCAW-S vs. FCAW-G essential variables breakdown and the AWS D1.1 Table 6.6 explainer for full lists.
Structuring the WPS Document
AWS D1.1:2025 Annex M provides the standard WPS form. For a dual-process WPS, you have two practical approaches:
Option A — Single form with process-designated columns. Use the Annex M form and clearly annotate which parameter ranges apply to the SMAW root passes and which govern the FCAW-G fill/cap passes. A column header like "SMAW (Pass 1 — Root)" and "FCAW-G (Passes 2+ — Fill/Cap)" removes ambiguity.
Option B — Separate WPS documents referencing the same dual-process PQR. Write a standalone SMAW WPS and a standalone FCAW-G WPS, each pointing to the same PQR test record. When your FCAW electrode changes, you revise only the FCAW-G WPS and issue a revision; the SMAW WPS is unaffected.
Most QC managers prefer Option B because each document is simpler for welders, inspectors, and AISC auditors to read. There is no risk of a welder confusing the SMAW parameter column with the FCAW-G column on a busy job site.
PQR Test Plate Requirements
The PQR test weld must replicate the production sequence. If the plan is SMAW root + FCAW-G fill/cap in production, the PQR test plate must be welded that way — SMAW root first, then FCAW-G fill and cap. A PQR welded 100% SMAW does not qualify the FCAW-G fill passes, and vice versa.
Standard mechanical tests for a groove weld PQR under AWS D1.1:2025 include:
- Two transverse face bend and two transverse root bend specimens from plate thinner than 3/8 in, OR two side bend specimens from plate 3/8 in or thicker
- Two reduced-section tensile specimens
- Charpy CVN specimens if supplementary essential variables (Table 6.8) apply — typically for demand-critical or cyclically loaded welds
All mechanical tests run on the completed dual-process weldment. The PQR test report must document both the SMAW root parameters (amperage, voltage, travel speed, heat input) and the FCAW-G fill/cap parameters including shielding gas composition, wire feed speed, CTWD, and voltage. A PQR tensile and bend test requirements summary provides a field-ready checklist.
Prequalified Status Does Not Extend to Combined Procedures
SMAW with E7018 low-hydrogen filler is prequalified under AWS D1.1 for many joint configurations. FCAW-G with E71T-X designations is also a prequalified process. However, the dual-process combination is not automatically prequalified — Clause 5 prequalified WPS rules do not explicitly sanction a mixed-process sequence in a single joint pass schedule. In practice, most structural engineers and quality programs require a dual-process WPS to be qualified by PQR.
Confirm with your Engineer of Record or contract specification before assuming prequalified status for a combined procedure. The cost of a PQR is far less than an audit finding that invalidates production welds.
Tracking Essential Variable Compliance in Production
Production parameter logging for dual-process WPS must separate the SMAW root pass record from the FCAW-G fill/cap record. If your WPS controls heat input (common on A514, A913, or CVN-required joints), calculate arc energy separately for each process — the heat input formula and documentation requirements article covers the calculation in detail.
When your CWI reviews production weld records, they should be able to trace each pass range to the governing process, the electrode lot (heat number for covered electrodes, package heat number for FCAW-G wire), and the qualified parameter ranges. This traceability is a standard review point at AISC certification audits and third-party inspections.
Pre-Production Checklist
Before running a dual-process SMAW root/FCAW-G fill procedure, verify:
- PQR test plate was welded using both processes in production sequence
- SMAW electrode classification and hydrogen designator are documented on the WPS
- FCAW-G wire classification, shielding gas composition, and CTWD range are specified
- Pass-range boundaries are unambiguous on the WPS document
- Each process has its own parameter log column in your production traveler
- CVN supplementary essential variables (Table 6.8) are evaluated if the joint is demand-critical or seismically loaded
Managing two sets of essential variables is straightforward once the WPS and PQR are structured correctly. The trap is assuming that a single-process PQR carries over to both — it does not, and that assumption is one of the most common findings during third-party procedure audits.
Rule library based on AWS D1.1:2025; verify against your governing edition.
Track your dual-process WPS qualifications alongside your full PQR library with WPS Welding — built for CWIs and QC managers who need audit-ready records, not spreadsheet workarounds.