A516 Gr.55/60 Preheat for SAW — 3/4" to 1-1/2"

SAW (Submerged Arc Welding)

SAW submerges the arc beneath granular flux for highest deposition rates, flat/horizontal only. Category B in Table 5.11.

For pressure vessel longitudinal and circumferential seams, SAW is the primary process. Tandem or multi-wire configurations on specialized manipulators achieve consistent quality over seam lengths exceeding 40 feet. Flux basicity index per ASME Section II Part C determines the mechanical properties of the weld deposit.

SAW Tips for Pressure Vessel and Low-Temperature Steels

For A516 Grades 55/60 pressure vessel plate (30–32 ksi yield), SAW is the primary shop process for tank shell and vessel seam welding. F7A2-EM12K at 550–700 A handles longitudinal shell seams with 20–30 lb/hr fill rates. Use neutral flux (N designation) for multi-pass seams to avoid excessive Si and Mn pickup across weld passes. Active flux (A) is acceptable for single-pass nozzle attachment fillets.

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

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.

A516 Gr.55/60

ASTM A516 Grades 55 and 60 are carbon steel plates designed for moderate and lower temperature pressure vessel service. Grade 55 (55 ksi tensile, 30 ksi yield) and Grade 60 (60 ksi tensile, 32 ksi yield) are widely used in storage tanks, heat exchangers, and process drums. Chemistry limits (0.24% max carbon for Gr.55, 0.27% max carbon for Gr.60 on thicker plate) and typical carbon equivalent of 0.38-0.44 qualify them for both Category A (non-low-hydrogen) and Category B preheat in Table 5.11. A516 is produced in plate thicknesses from 1/4" through 12". Grades 55 and 60 may be ordered as-rolled, normalized, or stress-relieved depending on the ASME Code requirements for the specific vessel design temperature and thickness.

Why This Preheat for A516 Gr.55/60 with SAW

Pressure vessel plate for storage tanks and heat exchangers at moderate strength. 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 A516 Gr.55/60

Specified for atmospheric storage tank shells per API 650, heat exchanger tube sheets, air receiver vessels, condensate drums, deaerator shells, and low-pressure separator vessels. A516 Gr.60 is the workhorse for ASME VIII Division 1 vessels under 650°F design temperature. Shell-to-head circumferential seams and nozzle reinforcement pads are the primary weld details. Plate thicknesses for API 650 tank shells typically range from 5/16" at the top course to 1" or more at the bottom course depending on tank diameter and liquid specific gravity. Vertical seam welds carry the full hydrostatic head and require complete joint penetration with radiographic examination. Tank diameters range from 15 feet for small day tanks to over 300 feet for crude oil terminal storage. Shop-welded vessel shells are rolled from flat plate with longitudinal seams welded first, then circumferential seams joining shell courses together on the vessel rotator.

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"

A516 Gr.55/60 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.

A516 Gr.55/60 Welding Guides