... and outside water tank shell all are welded by argon arc.3. The tubes and frame are adjustable, power bearing ... size420,460,470,475,480,500mm or Customer demandWelding:Argon arc weldingVACUUM TUBESTube structureAll-glass double deck co-axial structureGlass materialHigh ... *30275L VACUUM TUBE Its production process1.plate Cutting 2.Punching3.Welding 4.Pressing 5.Edge(device)6.Leakage 7.Foaming8.Packing ...