LSAW(Longitudinally Submerged Arc Welding Pipes)use single plate steel as raw material, applied double-sided submerged arc welding. The finished products have larger specifications and the welding joints have excellent ductility, plasticity and good sealing. LSAW pipes have large diameter, thick wall and can withstand high pressure and low temperature. LSAW pipes play a major role in oil and gas pipelines with features of high strength, high quality and long distance. According to the standard of American Petroleum Institute (API), the LSAW pipe is the only designated pipe in large scaled oil and gas transportation, especially when the pipelines cross the densely populated urban areas and the first and second class cities.