METHOD FOR MAKING ELECTRICALLY WELDED METALLIC TUBES Russian patent published in 2000 - IPC

FIELD: metallurgical production, possibly manufacture of electrically welded tubes for main water ducts laid for long distance and satisfying high demands to their surface quality, cleanness, structure and properties of surface microlayer. SUBSTANCE: method for making electrically welded metallic tubes comprises steps of cleaning surface of metallic belt, shaping belt of tube blank, welding its edges. Cleaning of belt surface is carried out in line of tube welding mill in vacuum chamber by means of electric arc discharge in mode corresponding to raising portion of volt-ampere characteristic and with use of graphite as anode. Process of welding tube edges is followed by fusion of inner burr by means of electric arc burner with non-consumable electrode in atmosphere of protective, reducing or protective-reducing gas. EFFECT: enhanced quality of electrically welded tubes due to preliminary cleaning of belt surface, high quality of welded joint and reduced size of inner burr. 1 dwg