A36 Preheat for SAW — 3/4" to 1-1/2"
Per AWS D1.1:2025 Table 5.11, the minimum preheat for A36 welded with SAW at 3/4" to 1-1/2" is 50°F (10°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 3/4" to 1-1/2"
Why SAW for A36 at 3/4" to 1-1/2"? 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 50°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 3/4" to 1-1/2"
Preheat climbs at this range as thicker material slows heat dissipation, trapping hydrogen at crack-susceptible grain boundaries.
Other Steels with SAW at 3/4" to 1-1/2"
| Steel | Category | Preheat |
|---|---|---|
| A53 Gr.B | B | 50°F (10°C) |
| A633 Gr.E | C | 150°F (65°C) |
| A709 HPS70W | C | 150°F (65°C) |
| A710 Gr.A | C | 150°F (65°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 in the 3/4 to 1-1/2 inch range with SAW is the high-deposition shop combination for primary structural fabrication — plate girder long-seam welds, beam-flange-to-web automated welds on built-up sections, and continuous-fillet runs on heavy A36 stiffener-to-flange details where the controlled-environment SAW process delivers high deposition rate and the 50°F preheat floor is binding on the section thickness.
Pre-weld notes
Three constraints layer at this combination. First, the 50°F preheat floor needs active verification per Clause 7.6 — the heated zone must extend at least twice the base-metal thickness from the welding point. Second, electrode-flux combination per Table 5.7 — A36 sits in Group I, with SAW columns listing F6XX-EXXX, F6XX-ECXXX, F7XX-EXXX, F7XX-ECXXX combinations under A5.17/A5.17M and A5.23/A5.23M. Third, flux conditioning per Clause 7.3.3 — flux must be dry, damaged packages discarded or dried at 500°F minimum for one hour, top-inch discard rule when used from an opened package, and reclaimed flux per Clause 7.3.3.3 must use a system maintaining constant composition and particle-size distribution at the weld puddle.
What a CWI verifies
A CWI on A36 SAW mid-thickness shop work verifies (1) preheat at perimeter and samples mid-joint with a contact pyrometer after the first pass group, (2) electrode-flux combination against Table 5.7 Group I, (3) flux dryness and the storage log, and (4) current and layer width against Table 5.2 prequalified SAW limits for the specific electrode configuration. The 50°F floor is closer to binding at this thickness than at thin section — winter shop conditions or large-section heat-sink effects can put base metal below the floor without obvious signal.