This closed head orbital welding uses a modular sealed welding head to achieve zero-defect welding in an inert gas protection environment. It supports pipe diameters of 10-200mm, welding thickness of 0.5-8mm, and uniform inner wall molding without oxidation. In addition, the weld seam Ra of this closed head orbital welding is ≤0.4μm, which meets the 3A hygiene standard. An optional remote monitoring module can be used to record the welding data chain in real time.