Submerged arc welding (SAW) is a high-deposition process. To push deposition even higher, some shops use supplemental filler addition — feeding additional filler wire (cold wire or hot wire) into the molten pool alongside the main electrode. This is common on heavy-plate production where deposition rate is the bottleneck.
AWS D1.1:2025 Table 6.6 row 7 sets a tighter threshold on changes to the electrode-to-supplemental-filler ratio than the 2020 edition. Here's what changed.
What "ratio" actually means
If your SAW procedure deposits weld metal from two sources:
- The main electrode (consumable wire being arced)
- The supplemental filler (added wire, no independent arc)
…then the ratio is the proportion of deposited mass from each. A 70/30 ratio means 70% of the weld metal mass comes from the electrode and 30% from supplemental filler.
The ratio is calculated from feed rate × wire density. Most SAW power supplies that support supplemental filler track this automatically.
What changed in 2025
2020 edition: Table 6.5 row 7 used a different tolerance and slightly different wording on the ratio threshold.
2025 edition: Table 6.6 row 7 specifies that a change of more than ±10% in the electrode-to-supplemental-filler ratio is an essential variable change.
If your PQR was qualified at 70/30, the production WPS can run at ratios between 60/40 and 80/20 without requalification. A 50/50 ratio would be outside the qualified envelope.
Why the ratio matters
The ratio affects:
- Heat input — supplemental filler dilutes the heat per unit weld metal deposited
- Cooling rate — more cold-wire addition means faster local cooling
- Microstructure — different ratios produce different HAZ characteristics
- Mechanical properties — particularly toughness, when CVN is required
Two SAW procedures with the same amperage and voltage but different ratios produce different welds. The 2025 row 7 tightening reflects this.
How to document on a WPS
The electrical and parameter block expands when supplemental filler is in use:
SAW parameters:
Number of electrodes: 1 (single wire) + 1 supplemental
Main electrode: A5.17 EM12K, 5/32 in diameter
Supplemental filler: A5.17 EM12K, 3/32 in diameter (cold wire)
Main electrode amperage range: 450-700 A
Main electrode voltage range: 28-34 V
Travel speed range: 16-26 ipm
Supplemental filler feed rate: 35-65 IPM
Electrode-to-supplemental ratio: 70/30 ± 10% (PQR-25-014 qualified at 70/30)
The supplemental filler block is mandatory when supplemental is in use. Without it, the WPS doesn't accurately describe the procedure.
Cross-check during production
The ratio is verifiable from feed-rate measurement on the power supply:
- Main electrode feed rate (in/min) × cross-section area × density = main mass rate
- Supplemental filler feed rate × cross-section area × density = supplemental mass rate
- Ratio = main / (main + supplemental)
A production log should record both feed rates at the start of each weld and at intervals. Out-of-range ratios are detectable in real time.
Common findings on SAW WPSs
- WPS doesn't address supplemental filler when it's in use. The procedure on the floor doesn't match the WPS.
- Ratio listed without tolerance. "70/30" by itself doesn't tell the welder how much variation is allowed.
- Cited PQR didn't qualify with supplemental filler. A 100% main-electrode PQR doesn't support a WPS that uses supplemental.
- Migration to 2025 edition without re-checking row 7. Old 2020 tolerances may have allowed wider ratio variation than 2025 permits.
- Production records don't include supplemental feed rate. Ratio compliance unverifiable.
What this means in practice
For shops running ordinary single-wire SAW: no change. The 2025 row 7 rule doesn't apply.
For shops running SAW with supplemental filler:
- Audit your existing WPSs for the supplemental filler block
- Cross-check PQR qualification against the 2025 ±10% tolerance
- Verify production records include supplemental feed rate
- Update WPS revisions to cite the 2025 edition and row 7 tolerance
Most affected shops will find their existing PQRs still support production at the 2025 ±10% tolerance — the tighter rule mostly catches outlier shops that were running supplemental ratios far from the PQR baseline.
A rule engine that encodes Table 6.6 row 7 and reads the supplemental filler block of the WPS catches violations at draft time and during the edition migration.