A913 Gr.80 Preheat for SMAW-LH (H4) — up to 3/4"

SMAW-LH (H4) for A913 Gr.80 at up to 3/4"

H4-certified SMAW-LH (H4) for A913 Gr.80 at up to 3/4": minimum preheat 32°F (0°C) under Category G. H4 is the strictest hydrogen control in AWS, requiring 4 mL/100g maximum per A4.3. For E7018, only select manufacturing lots from specific producers consistently achieve H4 levels. The electrode must carry an explicit H4 designator — H8-certified rods do NOT automatically qualify as H4. Rod oven storage at 300°F (not the standard 250°F) is recommended by some manufacturers for H4 electrodes. Exposure time out of the oven should be limited to 2 hours maximum, more restrictive than the standard 4-hour limit.

SMAW (Low-Hydrogen)

Low-hydrogen SMAW (E7018/E7016) uses basic-coated electrodes requiring rod oven storage, assigned to Category B in Table 5.11.

For high-strength shapes and plate, E7018 provides adequate tensile match for steels up to Category C. E8018-C3 or E9018-M may be required for higher-strength steels to meet weld metal strength matching requirements. Bead sequencing on thick TMCP flanges should follow qualified WPS parameters precisely to avoid overheating the refined microstructure.

SMAW-LH Tips for High-Strength and TMCP Steels

For A913 Grade 80 TMCP shapes (80 ksi yield, Category G, H4 required exclusively), only H4-designated electrodes are prequalified — the E7018-H4 designation requires AWS A4.3 testing at 4 mL/100g maximum. Higher-strength electrodes (E8018-M-H4 or equivalent) may be needed to match 80 ksi yield. Rod oven temperature and exposure time rules per §7.3.2.1 and §7.3.2.4 are more critical on H4.

Typical values for reference — always verify against your approved WPS and electrode manufacturer data.

Why SMAW-LH (H4) for A913 Gr.80 at up to 3/4"

Why SMAW-LH (H4) for A913 Gr.80 at up to 3/4"? SMAW-LH (H4) delivers 3-5 lb/hr deposition — compared to SAW (H4) at 15-40 lb/hr. Position capability: all positions. Suitability: field and shop. The H4 designation provides the strictest hydrogen control available, which is mandatory for this steel grade under Table 5.11 — no other hydrogen level or standard low-hydrogen process is prequalified.

A913 Gr.80

ASTM A913 Grade 80 (80 ksi yield, 95 ksi minimum tensile) is the highest-strength TMCP shape specification in D1.1, produced exclusively by the QST process. It requires H4-certified consumables (the strictest hydrogen control at ≤4 mL/100g deposited weld metal per AWS A4.3) and falls exclusively under Category G, which has four thickness-dependent preheat tiers (32°F up to 3/4”, 50°F up to 1-1/2”, 150°F up to 2-1/2”, 225°F above). No other hydrogen designation, standard low-hydrogen, or non-low-hydrogen SMAW is prequalified for this grade under Table 5.11. The H4 requirement limits the available consumable pool significantly — only select electrode classifications carry the H4 designator. A913 Gr.80 availability is limited to heavy W14 column sections from a small number of domestic and international mills, with procurement lead times typically 16-24 weeks.

Why This Preheat for A913 Gr.80 with SMAW-LH

Highest-strength 80 ksi TMCP shape requiring H4 consumables exclusively. This steel requires H4-certified consumables — the strictest hydrogen control in Table 5.11 at no more than 4 mL diffusible hydrogen per 100g. At 32°F with SMAW-LH, the four thickness-dependent preheat tiers in Category G reflect the balance between the steel's 80 ksi yield strength and the exceptional hydrogen control provided by H4 certification. No other hydrogen designation is prequalified for this grade.

Typical Applications for A913 Gr.80

Reserved for the most demanding column applications in super-tall structures, typically interior gravity columns carrying 50+ stories of tributary load. A913 Gr.80 allows W14 sections to replace built-up box columns, simplifying connections and reducing fabrication cost while maintaining equivalent axial capacity. Every weld on this grade demands verified H4 consumables and documented preheat compliance — no exceptions or substitutions are permitted under Table 5.11. Column splice CJP welds require UT inspection per D1.1 Table 8.2. Only a limited number of domestic mills produce A913 Gr.80 shapes, with lead times of 16-24 weeks for non-stock sizes. The H4 consumable requirement eliminates most standard electrode inventory and requires dedicated electrode orders for each project. Fabricators must establish verified H4 supply chains before bidding Gr.80 column work, as H4-designated electrodes are not stocked by most welding distributors. Rejected consumable certifications can delay erection schedules by weeks.

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.

H4-Certified Consumables for A913 Gr.80

Category G is exclusive to A913 Gr.80 and requires H4-certified consumables — the strictest hydrogen control in D1.1 at no more than 4 mL of diffusible hydrogen per 100g of deposited weld metal. Standard low-hydrogen or H8 consumables are not prequalified for this grade. The four thickness-dependent preheat tiers (32°F up to 3/4″, 50°F up to 1-1/2″, 150°F up to 2-1/2″, 225°F above) reflect the balance between A913 Gr.80's 80 ksi yield and the exceptional hydrogen control provided by H4 certification.

A913 Gr.80 with SMAW-LH (H4)

Try Different Combinations

Use the interactive preheat calculator to look up any steel, process, and thickness combination from D1.1:2025 Table 5.11.

A913 Gr.80 Welding Guides