We are welding tie-in points of large diameter SS Ducting where it is inaccessible inside to perform counter welding. We plan to use TGX filler metals (Flux Cored - GTAW Process). My question is, Do we need to qualify welders for this filler wire, if we already have welders who are qualified with GTAW process ER 316L filler metal? And do we need to generate another WPS if we already have WPS for GTAW - ER 316L? Can any body from the forum help me?