apparatus for overheating the edges of a preheated formed skelp for the purpose of butt welding the skelp into pipe or tube . induction coil assembly consisting of two series connected loops , with a main conductor of each loop positioned within a magnetic flux guide and positioned adjacent to the open edges of the c - shaped skelp and the return conductors of each loop arranged externally on opposite side of the flux guide , providing localized overheating of the edges of the skelp prior to welding .