Stainless steel pipe welding generally includes root welding, filler welding, and cap welding. Among them, root welding is the key step that determines weld strength and project quality. Depending on site conditions, root welding is typically divided into two categories: with argon back-filling and without argon back-filling.
Argon Back-Filling Methods
Plugging Plate + TIG (Solid Wire)
During prefabrication, plugging plates and adhesive tape are used to seal both sides of the weld joint, ensuring a high-purity argon atmosphere inside the pipe. This effectively prevents oxidation and produces reliable root welds.
Water-Soluble Paper + Plugging Plate + TIG
Commonly used in installation welding where ventilation is difficult. Water-soluble paper seals hard-to-access sides, while plugging plates are used where removal is easier. This method ensures good protection but requires careful application and experienced welders to avoid oxidation problems.
Non-Argon Back-Filling Methods
Flux-Cored Wire + TIG
Widely used for on-site welding with wires such as E308, E309, and E316 series. This method eliminates argon back-filling, offering low cost and high efficiency, but demands skilled operation due to fast wire feeding and precision requirements.
Coated Wire (Self-Shielded Flux-Cored Wire) + TIG
Newer coated wires such as TGF308 and TGF316L use slag and alloying elements to protect the root weld. This process is efficient, cost-effective, and reliable, achieving excellent weld quality in actual projects. Proper torch angles (70°–80°) and current control are essential for best results.
Conclusion
Each stainless steel root welding method has unique advantages and limitations. Argon back-filling methods ensure maximum protection but require more preparation, while non-filling methods simplify operations and reduce costs, though they need higher welder skill.
In practice, the choice of welding method should balance project requirements, cost, quality, and construction schedule to ensure safe and durable results.
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