METHOD OF MANUFACTURING ELECTRIC RESISTANCE WELDED TUBE EXCELLENT IN PROPERTY OF WELD ZONE

摘要

PROBLEM TO BE SOLVED: To provide a method of manufacturing an electric resistance welded tube excellent in the properties of a weld zone by which the toughness of the weld zone which is required for the electric resistance welded tube for line pipes of oil wells and the strength of the weld zone which is required for the electric resistance welded tube for casing pipes of the oil wells are attained. SOLUTION: After imparting a tapered shape in which a slope 13 is connected to an end face 12 approximately perpendicular to the width direction of a strip material by fin pass forming 3 on the way of a process in which the strip material is made into a tube by forming the strip material, butting the end parts to each other and performing electric resistance welding, the electric resistance welding is performed by taking the amount of upset in squeezing rolls when performing the electric resistance welding as 0.5-2.0% of the outer peripheral length. It is preferable that the slope 13 is 25-50°in the inclined angle from the end face 12 and the length in the thickness direction of the strip material of the slope is 20-45% of the thickness of the strip material. COPYRIGHT: (C)2008,JPO&INPIT