Development Process of Large-Diameter Welded Pipe Production Units

The production methods for manufacturing large-diameter longitudinal submerged arc welded (LSAW) pipes (ranging from 20 to 64 inches) used in oil and gas transmission pipelines primarily include the UOE method, RBE method, C-forming method, JCOE method, HU-METAL method, and full-row roller forming method. Among these forming methods, the UOE method produces pipes with the best quality and highest reliability. However, due to the substantial investment required for constructing UOE units, no new units have been built since the 1980s. The roll bending forming process, originally mainly used for producing large-diameter structural pipes (with a maximum outer diameter of 4000mm), has undergone a series of improvements, significantly enhancing the performance and reliability of the LSAW pipes produced. Consequently, this process is now also used for manufacturing oil and gas transmission pipes. Due to its high production flexibility and significantly lower equipment investment compared to UOE units, the roll bending forming process has been promoted and applied in some developing countries. This is the currently widely recognized RBE method. According to statistics, since the 1990s, of the 13 large-diameter LSAW pipe production units built overseas, several are RBE units. Additionally, in recent years, Germany's SMS-Demag company has developed the PFP forming method for producing large-diameter LSAW pipes, which has been successfully implemented in three factories (one of which can produce large-diameter thick-walled stainless steel pipes). Large-diameter spiral submerged arc welded (SSAW) pipe production units have continued to be constructed in some countries in recent years, not only for producing structural pipes but also for manufacturing oil and gas transmission line pipes. The maximum steel grade of the produced oil and gas transmission pipes has reached X80.