The differences between ERW, SSAW, LSAW

Straight seam high frequency welded pipe (ERW) is divided into induction welding and contact welding according to different welding methods. Compared with the spiral welded pipe, the cutting and other processes have the advantages of short weld seam, high dimensional accuracy, uniform wall thickness, good surface quality, and high pressure. ERW is currently widely used in urban gas, crude oil and refined oil transportation.

Spiral Submerged Arc Welded Pipe (SSAW) refers to a metal pipe with spiral seam welded by submerged arc welding process. Steel pipes of various diameters have a wide range of raw materials, the weld can avoid the principal stress, and the stress is better. The disadvantage is that the geometric size is poor. Welding defects such as slag inclusion and welding deviation, the welding stress is in the state of tensile stress.

Longitudinal submerged arc welded pipe (LSAW) is produced by pressing (rolling) a single medium and heavy plate into a tube blank in a mold or a forming machine, using double-sided submerged arc welding and expanding its diameter. The finished product has a wide range of specifications, good toughness, plasticity, uniformity and compactness of the weld, and has the advantages of large pipe diameter, pipe wall thickness, high pressure resistance, low temperature resistance and strong corrosion resistance. In the construction of high-strength, high-toughness, high-quality long-distance oil and gas pipelines, most of the steel pipes required are large-diameter thick-walled straight seam submerged arc welded pipes. According to API standards, in large-scale oil and gas pipelines, when passing through Class 1 and Class 2 areas such as alpine regions, seabeds, and urban densely populated areas, LSAW pipe is the only designated applicable pipe type.