Selection Guide for Electric Welding Machines in Steel Structure Industry: How to Match Submerged Arc Welding and Gas Shielded Welding to Different Engineering Requirements.
1. Classification and welding requirements of steel structure projects
| Heavy-duty industrial plants (H-shaped steel, box-type columns) | |
| Typical components | Main beams/columns (plate thickness 20~50mm) |
| Node welds (full penetration requirements) | |
| Core requirements | High-efficiency long weld welding |
| Low heat input to control deformation | |
| Long-span bridges (steel box beams, trusses) | |
| Typical working conditions | Outdoor construction (wind and moisture resistance) |
| Thick plate butt joint (30~80mm) | |
| Special requirements | Must comply with JT/T 722-2023 bridge welding specifications |
| Low-temperature impact toughness (-40℃) | |
| Pressure vessels/tanks (vertical seams, circumferential seams) | |
| Core standards | NB/T 47014-2023 Welding process assessment for pressure-bearing equipment |
| 100% non-destructive testing (UT/RT) | |
| Technical difficulties | Control of drooping of molten pool in vertical welding position |
2.Comparison of Submerged Arc Welding (SAW) and Gas Shielded Arc Welding (MAG) Technology
| Parameters | Submerged arc welding (SAW) | Gas shielded welding (MAG) |
| Applicable thickness | 6~150mm (preferably 20mm or more) | 1~50mm (optimal 3~25mm) |
| Welding speed | 40~120cm/min (high speed) | 15~50cm/min (medium speed) |
| Deposition efficiency | 8~12kg/h (extremely high) | 3~6kg/h (medium) |
| Weld quality | Beautiful shape, few pores | Requires strict wind protection, more spatter |
| Automation | Suitable for gantry automatic welding | Both robot and manual semi-automatic are available |
| Typical applications | Longitudinal seams of box columns, circumferential seams of storage tanks | Beam-column joints, on-site installation welding |
3. Selection scheme according to engineering scenario
① Heavy-duty plant H-beam production line
Recommended process:
● Submerged arc welding: for flange plate-web plate T-joint fillet weld (with gantry)
● Gas shielded welding: for short welds such as ribs and connecting plates (argon-rich mixed gas 80% Ar+20% CO₂)
②Bridge steel box girder manufacturing
● Special requirements: welding materials need to match the parent material weathering steel (such as AWS A5.28 ER110S-G)
● Process combination:
Base welding: gas shielded welding (more flexible control of root gap)
Filling cover: submerged arc welding (improve efficiency)
Wind resistance solution: configure windproof shed + flux recovery system (essential for outdoor construction)
③ 100,000 m³ crude oil storage tank vertical seam welding
● Vertical welding challenge: undercut caused by falling molten pool
● Solution:
Electrogas vertical welding (EGW)
Special water-cooled slider for forced forming
Flux-gas joint protection (SAW+GMAW composite)
