A36 Preheat for SAW — up to 3/4"
Per AWS D1.1:2025 Table 5.11, the minimum preheat for A36 welded with SAW at up to 3/4" is 32°F (0°C), Category B. Preheat below this raises hydrogen-cracking risk in the heat-affected zone; the same temperature is the minimum interpass limit maintained through the weld.
Built on AWS D1.1:2025 Table 5.11 — every value traced to the clause.
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SAW (Submerged Arc Welding)
SAW submerges the arc beneath granular flux for highest deposition rates, flat/horizontal only. Category B in Table 5.11.
SAW with F7A2-EM12K wire/flux delivers the highest deposition rates for flat-position fillet welds on building steel. Typical parameters: 500-700 amps, 28-32 volts, 18-30 IPM travel speed. Flux consumption runs approximately equal to wire consumption by weight. Unfused flux recovery and recycling systems are standard in production shops to control consumable costs.
Why SAW for A36 at up to 3/4"
Why SAW for A36 at up to 3/4"? SAW delivers 15-40 lb/hr deposition — the highest deposition rate among available processes. Position capability: flat and horizontal only. Suitability: shop only.
Filler Metal for SAW
Wire: EM12K or EL12 with matching flux (AWS A5.17). Common combo: F7A2-EM12K. Diameter: 3/32" or 7/64". Flux type: active (A) for single-pass, neutral (N) for multi-pass. Voltage: 28-34V. Current: 400-800A depending on joint size. Travel: 12-24 ipm.
Typical values for reference — always verify against your approved WPS and electrode manufacturer data.
A36
ASTM A36 is the most commonly specified structural steel in North America, with a minimum yield strength of 36 ksi and 58-80 ksi tensile range. It appears in both Category A (non-low-hydrogen SMAW) and Category B (low-hydrogen processes) of Table 5.11. A36 is available as plate (up to 8" thick), W-shapes, channels, angles, and bars from virtually every domestic mill. Its moderate carbon content (0.26% max for shapes, 0.25% max for plate up to 3/4") and typical carbon equivalent of 0.35-0.42 give it good weldability across all prequalified processes. A36 plate thicker than 1-1/2" carries a slightly higher carbon limit of 0.29%, while plate from 3/4" to 1-1/2" stays at 0.25% max.
Why This Preheat for A36 with SAW
Widely used structural carbon steel with 36 ksi yield and 0.26% max carbon. With low-hydrogen SAW, this combination falls under Category B rather than Category A — the submerged arc process with granular flux produces controlled hydrogen levels, with flux condition being the primary variable. The 32°F minimum preheat is lower than what non-low-hydrogen SMAW would require at the same thickness because SAW significantly reduces the driving force for hydrogen-induced cracking in the heat-affected zone.
Typical Applications for A36
Common in angle-to-gusset fillet welds, beam web clip angles, stiffener plates, base plate bearing connections, light bracing members, stair stringers, handrail posts, and miscellaneous steel fabrication. A36 plate is the default choice for connection elements such as shear tabs, moment end plates under 36 ksi demand, and simple beam-to-column seated connections. In retrofit and renovation, A36 angles and channels are standard for reinforcement brackets and framing infill. Typical shop drawing callouts include 3/8" and 1/2" A36 plate for gussets, 5/16" fillet welds on clip angles, and partial joint penetration groove welds on base plate stiffeners. A36 is so ubiquitous that most structural steel shops maintain permanent inventory in multiple thicknesses from 1/4" through 2" plate. Fillet weld sizes on A36 connections typically range from 3/16" minimum to 5/8" for heavy gusset-to-column welds, with E70XX electrodes providing significant overmatching strength.
Why Preheat Matters at up to 3/4"
Thin material sheds heat quickly, allowing hydrogen to escape the HAZ readily — lowest preheat tier in Table 5.11.
Other Steels with SAW at up to 3/4"
| Steel | Category | Preheat |
|---|---|---|
| A53 Gr.B | B | 32°F (0°C) |
| A633 Gr.E | C | 50°F (10°C) |
| A709 HPS70W | C | 50°F (10°C) |
| A710 Gr.A | C | 50°F (10°C) |
A36 with SAW
Try Different Combinations
Use the interactive preheat calculator to look up any steel, process, and thickness combination from D1.1:2025 Table 5.11.
A36 Welding Guides
Primary sources
D1.1:2025 reference data. Not affiliated with AWS.
Application context
A36 plate at or below 3/4 inch with SAW is the high-deposition shop combination — automated plate girder fillet runs, beam-flange-to-web welds, secondary stiffener connections, and long-seam fillet runs on shop-fabricated structural assemblies where the controlled-environment SAW process delivers higher deposition rate and cleaner appearance than SMAW or GMAW.
Pre-weld notes
Three SAW-specific constraints sit on top of the 32°F preheat floor at this combination. First, electrode-flux combination per Table 5.7 — for Group I A36 the SAW columns list F6XX-EXXX, F6XX-ECXXX, F7XX-EXXX, F7XX-ECXXX combinations under A5.17/A5.17M and A5.23/A5.23M. Second, flux conditioning per Clause 7.3.3 — flux must be dry and free of contamination, packages must withstand six-month storage, damaged packages must be discarded or dried at 500°F minimum for one hour before use, and wet flux must not be used. Third, single vs parallel vs multiple electrode setup per Table 5.2 prequalified SAW limits — current windows, layer widths, and bead-size limits differ across the three configurations.
What a CWI verifies
A CWI on A36 SAW thin-section shop work verifies (1) electrode-flux combination classification against Table 5.7 Group I, (2) flux dryness and the storage log, (3) current and layer width against Table 5.2 prequalified SAW limits for the specific electrode configuration, and (4) any reclaimed or crushed slag flux against the Clause 7.3.3.3 and 7.3.3.4 reuse rules. The 32°F preheat floor is rarely binding at this thickness; flux discipline and electrode-flux conformance dominate the inspection effort.