Abstract: In a method for roll forming a flat metal strip through a roll forming machine into a round tubular product while the metal strip is being lengthwise fed therethrough, an improved method wherein regions of a specified width extending inward from the edges of said strip are imparted with substantially zero curvature. The tube forming method prevents decrease in the wall thicknesses at the edges when used in the manufacture of a thick walled electric welded pipe, and prevents the occurrence of edge buckling and springback when used in the manufacture of thick walled pipe so that in either case a proper and satisfactory butt junction for subsequent welding can be obtained.