A new type of martensitic stainless steel line pipe having excellent weldability and high corrosion resistance in wet CO₂ environments manufactured by the high-frequency electric-resistance welding (HF-ERW) process was developed on a commercial scale. The newly developed pipe is characterized by greater productivity compared with the conventional martensitic stainless steel seamless pipes, higher dimensional accuracy, in respect of thickness and outside diameter and capability of manufacturing thinner-wall pipes.