The Welding Torch is one of the parts needed to repair Ben's Chopper. The torch belongs to Maureen Corley, but was stolen by budding artist and junkyard owner Todd Newlan.
To bring the torch back to its rightful owner, Ben has to get into Todd's Trailer. Being polite doesn't work on Todd, though, since he just argues with Ben. Well, until he kicks the door down and knocks him out. He goes down that cool lift to the basement, and the torch is next to the workbench, among Todd's sculptures.