Submerged arc welding (SAW) is one of the highest-deposition processes used in structural fab, and it can be prequalified under AWS D1.1 — but not as broadly as SMAW or GMAW. Understanding where prequalification ends and mandatory PQR testing begins is a critical distinction for any QC manager building out a SAW-based welding program.
Getting this wrong in one direction — over-qualifying by treating every SAW procedure as needing a PQR — costs time and money on tests you didn't need. Getting it wrong in the other direction — claiming prequalification for a SAW configuration that requires PQR — puts you in violation of the standard, which any competent special inspector or AISC auditor will catch.
Rule library based on AWS D1.1:2025; verify against your governing edition — the AHJ or contract may specify 2020 or an earlier revision.
What Makes a SAW WPS Prequalifiable
AWS D1.1 allows prequalification for the single-arc automatic SAW process. This means one electrode wire fed automatically without manual adjustment of travel speed or wire feed rate during the weld. Automatic welding (as opposed to semi-automatic) requires a self-propelled welding head or a motorized carriage that maintains consistent parameters — the welder sets the parameters and the machine maintains them.
For a single-arc automatic SAW procedure to be prequalified, the following conditions must be met:
Electrode classification: The electrode must be classified under:
- AWS A5.17 — Carbon Steel Electrodes and Fluxes for Submerged Arc Welding, or
- AWS A5.23 — Low-Alloy Steel Electrodes and Fluxes for Submerged Arc Welding
The electrode classification must appear on the filler metal manufacturer's certification, and that cert must be in the filler metal traceability record tied to the WPS.
Flux-wire combination: The flux must be used in the combination tested or listed by the manufacturer with the specific wire classification. The flux manufacturer's documentation must support the mechanical properties required by the application — particularly if the connection design specifies a minimum tensile strength for the deposited weld metal.
Joint design: The SAW procedure must use one of the prequalified joint details from AWS D1.1 Annex B. For CJP groove welds in thick plate, this most commonly means double-V or single-V joints with sufficient groove angle and root opening for SAW's larger heat input and bead width.
Base metal: The base metal must be one of the prequalified materials listed in AWS D1.1 Annex A. All common structural grades — A36, A572, A992, A500 — are on that list.
When all of these conditions are met for a single-arc automatic SAW procedure on a prequalified joint design with a prequalified base metal, no PQR test is required.
What Cannot Be Prequalified
Three SAW configurations fall outside the prequalification scope in AWS D1.1 and always require a PQR:
Multi-arc SAW: Also called tandem SAW or twin-arc SAW, this configuration uses two or more electrode wires fed simultaneously or in tandem. Multi-arc SAW is widely used for high-deposition heavy-plate welding and girder fabrication, but it is not covered by prequalification. The interaction between arcs creates heat input and metallurgical conditions that the prequalified parameter tables do not anticipate. A PQR is required for every multi-arc SAW WPS.
Semi-automatic SAW: In semi-automatic SAW, the welder manually moves the welding gun or nozzle along the joint while the wire feed is automatic. The manual travel element introduces variability that takes the process outside the prequalified regime. If your operators are running a hand-held SAW torch, you need PQR support regardless of the base metal or joint design.
Electroslag Welding (ESW) and Electrogas Welding (EGW): These processes are sometimes grouped with SAW in discussions of high-deposition plate welding but they have entirely separate essential variable tables (Table 6.7 in AWS D1.1:2025) and are not prequalifiable. All ESW and EGW procedures require PQR testing.
The Essential Variables That Control SAW WPS Changes
Once a SAW WPS is established — either prequalified or PQR-supported — any change to an essential variable requires either a new PQR or an amendment to the existing WPS that stays within the qualified parameters.
The essential variables from AWS D1.1 Table 6.6 that most commonly trigger SAW WPS issues in production:
Flux classification change: Switching flux brands or grades is one of the most common sources of inadvertent essential variable deviation on SAW jobs. Different flux manufacturers may use different F-numbers even for nominally similar products. Before approving a flux substitution in production, the CWI or welding engineer must confirm the new flux falls within the same classification and F-number group as the original. For more on filler metal and flux traceability requirements, see SAW flux classification as an essential variable.
Wire diameter: AWS D1.1 Table 6.6 treats electrode diameter as an essential variable for SAW. Switching from 5/32 in to 3/16 in wire — even on the same classification — changes the current density, bead profile, and fusion characteristics enough to require PQR qualification or confirmation that the existing PQR covers the new diameter.
Number of wires: Adding a second arc to a single-arc SAW procedure converts the process to multi-arc SAW. This is an essential variable change that takes the procedure out of its qualified range entirely and requires a new PQR. This is a common gotcha on projects where shop productivity pressure leads to an equipment upgrade mid-project. See multi-wire SAW essential variable qualification for how to manage this properly.
Current type and polarity: Switching from DCEP (direct current electrode positive) to DCEN or to AC is an essential variable change. SAW procedures are frequently run on AC for thicker plate, and the flux behavior, penetration profile, and deposit chemistry all differ from DC conditions. The PQR must be run on the same current type and polarity as the production WPS.
Flux handling and moisture: This is not strictly an essential variable, but degraded flux is a leading cause of SAW weld discontinuities. AWS D1.1 addresses flux handling requirements — including reconditioned flux — separately from the essential variable framework. A WPS may be perfectly sound on paper while the flux being used has absorbed moisture that invalidates the mechanical properties documented in the flux certificate. See SAW flux handling and moisture control for the handling requirements a CWI should verify at the start of each shift.
Documenting a Prequalified SAW WPS
A prequalified SAW WPS requires the same Annex M form fields as any other prequalified WPS. For SAW, the critical entries that auditors and engineers look for:
- Process type: Single-arc automatic SAW (not "SAW" alone — specify automatic)
- Flux classification: Full A5.17 or A5.23 classification (e.g., AWS A5.17: F7A6-EM12K-H4)
- Wire classification: Match to flux combination on manufacturer's cert
- Polarity and current type: DCEP, DCEN, or AC — must match the PQR if PQR-based, or fall within the prequalified parameter range
- Wire diameter: Listed explicitly; any deviation from this diameter is an essential variable change
- Heat input range: Minimum and maximum heat input based on the tested or prequalified parameter envelope
- Preheat and interpass temperatures: Per AWS D1.1 requirements for the base metal and thickness being welded; document minimum preheat and maximum interpass temperature
For SAW procedures that do require PQR testing — multi-arc, semi-automatic, or any configuration outside the prequalified scope — the mechanical test results from the PQR must support every parameter range claimed on the WPS. The common failure mode is a WPS that claims a wider amperage or travel speed range than the PQR test actually covered. See multiple PQRs supporting a single WPS if you need to combine multiple test records to support a broad range WPS.
Summary: Before Your SAW WPS Leaves the QC Office
For any SAW WPS you're preparing or reviewing, run through this checklist:
- Is this single-arc automatic? If not, you need a PQR — prequalification is not available.
- Are the electrode and flux classifications under A5.17 or A5.23?
- Does the joint design match an AWS D1.1 Annex B prequalified detail?
- Is the base metal on the Annex A prequalified list?
- Are all essential variables (wire diameter, current type, flux class, number of wires) explicitly documented on the WPS form?
- If PQR-based: does the PQR cover the full range of parameters claimed on the WPS?
A WPS management platform built for AWS D1.1:2025 workflows can enforce these checks automatically and flag any parameter entry that falls outside the qualified range — before the WPS reaches the shop floor.