Abstract: A welding system having a traveling base carriage, a carriage positioning mechanism engaging the base carriage; and a ring gear assembly mounted on the base carriage. The ring gear assembly will include: (i) two half ring sections, each having at least one gear track; (ii) a ring gear mount attaching each of the half ring sections to the base carriage, where the ring gear mounts allow the half ring sections to separate and guide the half ring sections into mating engagement. The system further includes at least one weld head assembly mounted on the ring gear assembly. The weld head assembly includes: i) a welding torch; ii) a torch positioner, and iii) a position sensor.