Abstract: Automatic orbital welding system for welding conduit sections. The system may include a weld head having a clamping assembly for aligning the conduit sections. The weld head may include an electrode for applying heat to the conduit sections. Inert purge gas is preferably passed through the conduit sections while the orbital weld is formed to exclude contaminants from the weld area. A purge assembly is preferably connected to one of the conduit sections. The purge assembly preferably includes a purge restrictor having a valve disposed therein to allow the pressure within the conduit sections to be precisely controlled within a predetermined range during welding to promote the formation of a suitable weld.