Weathering steel · AWS D1.1 Tables 5.6, 5.7, 5.9 and 5.11
ASTM A588 WPS: check product form and weathering-filler conditions
AWS D1.1/D1.1M:2025 Table 5.6 lists A588 plate in Group II through 8 in. (200 mm), and A588 shapes in Group II at all thicknesses. The same Table 5.6 group does not mean the plate cutoff disappears, and the weathering-filler branch depends on exposure and finish requirements.
A588 product form changes the Group II boundary
| Verified A588 product form | Table 5.6 result | Decision |
|---|---|---|
| Plate, thickness ≤8 in. or 200 mm | Group II | Use Group II for the Table 5.7 filler-matching input within this listed plate range. |
| Plate thicker than 8 in. or 200 mm | Not covered by this A588 plate entry | Do not extend this Group II listing beyond its stated plate limit; resolve the governing material basis. |
| Shapes, all thicknesses | Group II | The listed shape entry has no thickness cutoff in Table 5.6. |
Use the applicable code unit column and its stated boundary. A shape and a plate of the same nominal thickness do not have the same Table 5.6 limit for A588. Verify product form and grade from the material records.
Category B is a separate temperature check
The curated Table 5.11 entry lists A588 in Category B. Category B applies to low-hydrogen SMAW and to SAW, GMAW or FCAW. For a 25 mm joint using GMAW, the SI Category B Table 5.11 step is 10°C. This example states only that table step for the stated process and thickness; actual minimum preheat must also account for the other base metal, the thickest part at the weld, starting temperature and any applicable code or project requirement.
Do not derive the preheat category from the Group II label. Table 5.6 supplies the filler-matching group; Table 5.11 supplies a separate process/material temperature path.
When weathering filler matching applies
For weather-exposed steel that will remain bare and unpainted, where similar atmospheric-corrosion resistance and color are required, Clause 5.6.3 directs the filler combination to Table 5.9. Confirm the required combination from the governing table and the actual consumable classification; this page does not select a corrosion-matching series from the grade name alone.
| Production condition | Filler decision to verify | Boundary |
|---|---|---|
| Bare, unpainted weathering application requiring similar corrosion resistance and color | Use the applicable Table 5.9 filler combination | Verify the complete electrode/flux classification and project requirement. |
| Single-pass groove weld under the weathering-steel condition | Clause 5.6.3.1 permits the stated Group II Table 5.7 filler exception | Apply only to the stated single-pass groove exception; other requirements remain. |
| Single-pass fillet weld under the weathering-steel condition | Clause 5.6.3.2 permits Group II Table 5.7 filler subject to the process size ceiling | SMAW ≤1/4 in. (6 mm); SAW/GMAW/FCAW ≤5/16 in. (8 mm). |
The single-pass exceptions are narrow; they do not make every Group II filler suitable for a weathering application or waive other Clause 5 limits. AWS-005 corrected the process-table cross-reference for this weathering exception to Clause 5.6.3; do not confuse it with the separate strength overmatching rule in 5.6.2.
What the A588 material entry cannot decide
- Confirm A588 grade and product form from the actual material documents. Do not use the shape entry for a plate beyond the listed plate limit.
- Table 5.6 Group II does not establish full Clause 5 prequalification. Check both base metals, their combination, joint detail, process, filler/gas/flux, position, thickness, preheat and project conditions.
- Weathering filler matching is conditional on the application and specified corrosion/color requirement. Do not treat every A588 job as identical or assume that a product label proves Table 5.9 matching.
- An existing-PQR route requires actual qualification records and the applicable material and process coverage checks; the Table 5.6 listing is not PQR coverage.
Edition and source
Material group and product form: AWS D1.1/D1.1M:2025 Table 5.6, printed pages 73–76. Filler matching and weathering provisions: Tables 5.7 and 5.9; Clauses 5.6.2–5.6.3. Preheat category and temperature steps: Table 5.11, printed pages 81–84. This guide uses the 2025 base edition plus registered base-edition errata dated July 28, 2026; AMD1 is not included. The contract edition governs.
See the edition-basis page and other material guides.
Provide the exact product form and grade, material records, joint details, process and weathering/coating requirements.