A516 Gr.55/60 Preheat for SMAW (non-low-hydrogen) — up to 3/4"

SMAW (Non-Low-Hydrogen)

Non-low-hydrogen SMAW (E6010/E6011) uses cellulosic electrodes with higher hydrogen potential, assigned to Category A in Table 5.11.

For pressure vessel plate, non-low-hydrogen SMAW is typically limited to non-pressure attachments and temporary fit-up clips. Code requirements per ASME Section VIII often mandate low-hydrogen processes for pressure-retaining welds. Any E6010 tack welds on pressure boundaries must be completely removed before final low-hydrogen welding.

SMAW Tips for Pressure Vessel and Low-Temperature Steels

For A516 Grades 55/60 pressure vessel plate (30–32 ksi yield, Category A), non-LH SMAW is prequalified for non-pressure attachments and structural members. However, ASME Code construction for pressure-retaining welds on A516 requires low-hydrogen processes per ASME Section II and III requirements — E6010 is generally NOT acceptable for pressure-retaining vessel welds under the boiler and pressure vessel codes.

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

Why SMAW (non-low-hydrogen) for A516 Gr.55/60 at up to 3/4"

Why SMAW (non-low-hydrogen) for A516 Gr.55/60 at up to 3/4"? SMAW (non-low-hydrogen) delivers 3-5 lb/hr deposition — compared to SAW at 15-40 lb/hr. Position capability: all positions. Suitability: field and shop.

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 SMAW

Pressure vessel plate for storage tanks and heat exchangers at moderate strength. At this thickness, SMAW with non-low-hydrogen electrodes places the joint in Category A of Table 5.11. The minimum preheat of 32°F compensates for the higher diffusible hydrogen from cellulosic electrode coatings. The thicker the material, the longer hydrogen takes to escape the heat-affected zone, which is why preheat rises with thickness even for this common grade.

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 up to 3/4"

Thin material sheds heat quickly, allowing hydrogen to escape the HAZ readily — lowest preheat tier in Table 5.11.

Why 32°F for A516 Gr.55/60?

A minimum preheat of 32°F (0°C) means no active preheating is needed above freezing conditions. Table 5.11 Category A at this thickness assigns the ambient minimum because A516 Gr.55/60 with non-low-hydrogen SMAW has sufficient ductility and low enough carbon equivalent that hydrogen cracking risk is minimal at this section thickness. Per footnote (a), if working below 32°F, preheat the joint to at least 70°F (20°C) and maintain during welding.

Other Steels with SMAW (non-low-hydrogen) at up to 3/4"

A516 Gr.55/60 with SMAW (non-low-hydrogen)

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