LSAW steel pipe (Longitudinally Submerged Arc Welding abbreviated as LSAW) is a professional term for longitudinally submerged arc welding. LSAW steel pipe is made of single medium and thick plate as raw material. The steel plate is pressed (rolled) into tube blank in the mold or forming machine, and it is made by double-sided submerged arc welding and expanded diameter. The product has a wide range of specifications, good toughness, plasticity, uniformity and density of the weld, and has the advantages of large pipe diameter, pipe wall thickness, high pressure resistance, low temperature resistance and corrosion resistance. In the construction of high strength and high quality long distance oil and gas pipelines, most of the steel pipes needed are large diameter thick wall straight seam submerged arc welded pipes