Aluminum Welding for Pressure Vessels & Tanks

Why aluminum for pressure vessels & tanks

Aluminum offers a high strength-to-weight ratio; its naturally formed oxide film provides good corrosion resistance, and it shows no ductile-to-brittle transition at low temperature — which is why it is widely used in cryogenic tanks, transport tankers, and chemical and coastal vessels. Compared with steel vessels, aluminum vessels are substantially lighter, can dispense with an additional corrosion-coating step, and remain reliable in deep-cold duty such as LNG and liquid oxygen. For tankers where haulage cost and payload are decisive, the overall benefit of light weight is especially pronounced.

These vessels carry pressure and hold media, so the base metal is typically a 5xxx Al-Mg alloy — commonly 5083, 5086 or 5454. The joint strength and soundness of the weld directly determine whether the vessel passes acceptance. Filler selection is therefore the first step in process design: get it right, and procedure qualification and NDT proceed more smoothly thereafter.

Welding notes

Vessel welds usually undergo radiographic or ultrasonic inspection. The points below are proven welding-practice essentials; following them helps produce sound, porosity-free welds that pass mechanical testing, whether feeding by hand or by machine.

• Clean the surface thoroughly before welding. Remove the oxide film with a dedicated stainless-steel brush, then degrease with a solvent such as acetone to eliminate oil and moisture. Porosity largely originates from oxide film and oil and water contamination, so this step must not be skipped.
• Control porosity. Shield with high-purity argon, ensuring adequate gas flow and full nozzle coverage, and prevent drafts from disturbing the shielding gas at the arc. Keep the wire dry and clean, and avoid touching it with bare hands before feeding.
• Control interpass temperature in multi-pass welding. Thick-wall tanks usually require multiple passes; keep the interpass temperature in check between passes (generally below ~120°C for Al-Mg) and remove spatter and oxide as you go, avoiding excessive heat input. Overheating reduces both the strength and the corrosion resistance of the weld.
• Stable feeding gives a stable arc. Neatly layer-wound wire with a uniform, consistent diameter pays off across the run: clean payoff, no tangles, no snagging. Paired with a clean liner and matched drive rolls, it delivers a steady arc and even penetration, with fewer stoppages and smoother operation over long continuous welding. Good feedability and reliable supply are exactly the value TGM wire brings to general-industry production.

Further reading: for the troubleshooting sequence when porosity appears, pre-weld cleaning practice and shielding-gas checks, see the guide to aluminum weld porosity.