a complementary pair of top and bottom rolls for the initial breakdown step of a skelp in the manufacture of welded tubular products by rolling . the bottom roll has a convex midportion , a pair of concave end portions , and a pair of straight border portions each lying between the midportion and one of the concave end portions . the top roll is shaped in complementary relation to the bottom roll to define therebetween a path for the skelp . the breakdown roll pair of the above configuration makes it possible to curl the opposite edge portions of the skelp into arcs of a desired radius without the usual defects of rolling , and in such a way that the skelp can be subsequently rounded and have its edges welded together into a tube of minimal out - of - roundness .