PRODUCTION OF WELDED STEEL PIPE

PURPOSE:To improve welding quality and to stabilize welding by measuring the thickness size in both edge parts of stock steel sheets, then adjusting edge prepn. positions and welding conditions in accordance with the measured thickness size, groove size, etc. CONSTITUTION:The thicknesses in both edge parts of the steel sheets S are measured by a measuring instrument A and the edge prepn. is executed by a profiling roll 7, cutter 1, etc., of a milling type end face working machine for steel sheets to the measured thickness values. The steel sheets S are pressed after the edge prepn. and are formed by an O press, then the inside and outside faces in the butt part are welded. The edge prepn. position and welding conditions are adjusted in accordance with the measurement data of the thickness size or the groove size or the data on both thereof at this time. The size of the butt part is assured and the buckling and melt down by the butt pressure are prevented. The welding quality is, therefore, improved and the welding is stabilized.