Hebei Canghai Nuclear Equipment Technology Co.Ltd. It is made by rolling low-carbon carbon structural steel or low-alloy structural steel strip according to a certain spiral angle (called forming angle) into a tube blank, and then welding the tube seam together. it can be made with a narrower Strip steel produces large diameter steel pipes, its specifications are expressed by outer diameter and wall thickness, and the welded pipe shall be ensured that the hydraulic test, the tensile strength of the weld and the cold bending performance must meet the requirements.Technique：Electronic Resistance Welded (ERW ), Double Submerged Arc Welded (DSAW)，Electronic Fusion Welded (EFW).Inspection：With Chemical Composition and Mechanical Properties Analysis;Dimensional and Visual Inspection, also with Nondestructive Inspection.