ERW pipe and LSAW pipe are both straight seam welded pipes, which are mainly used for fluid transportation, especially long-distance pipelines for oil and gas. The main difference between the two is the welding process. Different processes make the pipe possess different characteristics and are suitable for different application scenarios.
The ERW tube uses high-frequency resistance welding and uses hot-rolled broadband steel coils as raw materials. As one of the most widely used pipes today, due to the use of rolled steel strips/coils with uniform and precise overall dimensions as raw materials, it has the advantages of high dimensional accuracy, uniform wall thickness, and good surface quality. The pipe has the advantages of short weld seam and high pressure, but this process can only produce small and medium-diameter thin-walled pipes (depending on the size of the steel strip or steel plate used as the raw material). The weld seam is prone to gray spots, unfused, grooves Corrosion defects. The currently widely used areas are urban gas and crude oil product transportation.
The LSAW pipe adopts the submerged arc welding process, which uses a single medium-thick plate as a raw material, and performs internal and external welding on the welding place and expands the diameter. Due to the wide range of finished products using steel plates as raw materials, the welds have good toughness, plasticity, uniformity and compactness, and have the advantages of large pipe diameter, pipe wall thickness, high pressure resistance, low temperature resistance and corrosion resistance. When constructing 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 the API standard, in large oil and gas pipelines, when passing through Class 1 and Class 2 areas such as alpine areas, seabeds, and densely populated urban areas, straight seam submerged arc welded pipes are the only designated pipe type.