Do you need actual weld time or do you need setup, fit up, purge and arc time? It's about 3/16" wall thickness so it will be a 2 pass weld. I'd say about 45 min of arc time would be safe to allow for grinding and cooling inbetween passes. I'm sure you will have guys that can get it done faster that don't allow much time for cooling and can slick her in with out much grinding. The Your talking GTAW for a process right?