This document specifies requirements for the approval of a welding process in a fixed plant, together with the requirements for subsequent welding production. It applies to new Vignole railway rails R220, R260, R260Mn, R320Cr, R350HT, R350LHT, R370CrHT and R400HT grade rails of 46 kg/m and above, as contained in EN 13674 1, welded by a flash butt welding process in a fixed plant and intended for use on railway infrastructure. This document applies to the welding of rails into welded strings.