A633 Gr.E Preheat for GMAW — 1-1/2" to 2-1/2"

GMAW (Gas Metal Arc Welding)

GMAW (MIG) feeds continuous solid wire with shielding gas — an inherently low-hydrogen process assigned to Category B in Table 5.11.

For pressure vessel work, GMAW with ER70S-6 provides excellent deposition rates on long seam welds. Gas backing with argon on back-purged root passes produces a smooth internal weld profile that satisfies radiographic acceptance criteria. Shielding gas purity is critical for vessel code quality; dew point must be below -40°F.

GMAW Tips for Pressure Vessel and Low-Temperature Steels

For A633 Grade E (60 ksi yield, Category C, CVN at -60°F), GMAW requires a higher-strength wire — ER80S-D2 or ER80S-G provides tensile matching at the 80 ksi minimum required. GMAW minimum 260 A with 0.045" wire handles groove fill passes on this grade. Category C preheat starts at 50°F (up to 3/4") and reaches 300°F above 2-1/2".

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

Filler Metal for GMAW

Common wire: ER70S-6 (AWS A5.18). Diameter: 0.035" for thin sections and out-of-position, 0.045" for production flat/horizontal. Shielding gas: 75/25 Ar/CO2 (standard), 90/10 Ar/CO2 (less spatter, better profile), or 100% CO2 (deeper penetration, more spatter). Contact-tip-to-work distance: 1/2" to 3/4".

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

A633 Gr.E

ASTM A633 Grade E is the highest-strength grade in this specification with 60 ksi minimum yield and 80 ksi minimum tensile strength (for plates up to 4”). Produced as normalized and tempered plate, it provides exceptional notch toughness with CVN testing at -60°F (15 ft-lbs transverse). Its higher strength level places it in Category C of Table 5.11, with correspondingly higher preheat requirements than the A/C/D grades. The quenched-and-tempered condition means carbon content is higher (0.22% max) with controlled manganese (1.15-1.50%) and silicon (0.15-0.50%), producing a CE-IIW of approximately 0.44-0.50. Like all Q&T steels, maximum interpass temperature must be respected to avoid degrading the tempered microstructure in the heat-affected zone during multi-pass welding.

Why This Preheat for A633 Gr.E with GMAW

Highest-strength A633 grade at 60 ksi yield requiring Category C preheat. The higher strength level of this steel places it in Category C of Table 5.11, which carries elevated preheat requirements compared to Category B grades. At 225°F minimum with GMAW, the continuous solid wire and gas shielding in GMAW produce inherently low hydrogen levels, typically 2-4 mL/100g, but the preheat must still ensure the cooling rate stays slow enough to prevent hydrogen-induced cracking in this higher-hardenability material.

Typical Applications for A633 Gr.E

Found in heavy-duty crane runway girders for steel mills, offshore jacket legs, polar Class vessels, cold-region bridge main members, large-span roof trusses in Arctic facilities, and load-bearing elements in LNG terminal structures. A633 Gr.E combines 60 ksi yield with excellent low-temperature toughness (CVN testing at -60°F), making it suitable for primary structural members in environments where both high static loads and extreme cold coincide. Procurement lead times for A633 Gr.E plate can be 12-16 weeks due to limited domestic production, and plate availability above 2" thickness may require international sourcing. Repair welding requires the same preheat procedures as original fabrication to maintain the guaranteed toughness properties. Filler metal selection must provide tensile matching (80 ksi minimum) and cold-temperature CVN values that equal or exceed the base metal specification. Weld mockups for offshore and LNG applications typically undergo CTOD or wide-plate testing.

Why Preheat Matters at 1-1/2" to 2-1/2"

Heavy plate with significant restraint and thermal mass — preheat is critical to maintain slow cooling for hydrogen escape.

Category C Preheat for A633 Gr.E

Category C in Table 5.11 applies to higher-strength steels where the combination of hardenability and residual stress requires elevated preheat. For A633 Gr.E at 1-1/2" to 2-1/2", the 225°F minimum preheat slows the weld cooling rate to prevent formation of crack-susceptible martensite in the heat-affected zone. Maintaining interpass temperature at or above this minimum is especially critical for multi-pass welds on restrained joints.

Other Steels with GMAW at 1-1/2" to 2-1/2"

A633 Gr.E with GMAW

Try Different Combinations

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

A633 Gr.E Welding Guides