1.The welder will start the welding by putting the 1st run joining the bottom of one rail and the mild steel insert ( item 4 ) . The 2nd run to be given for joining the bottom of the other rail and the mild steel insert. . Then subsequently welding to continue by depositing runs like fillet welding on the insert to complete the 1st layer. There should be complete fusion between rail ends and mild steel insert .Clean the slag properly after welding of each run.