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What is the Difference Between ERW, SSAW and LSAW Welded Steel Pipes?

Mar. 07, 2020

ERW Steel Pipe: high-frequency straight seam resistance welded pipe, which uses hot-rolled wide coils as raw materials and undergoes pre-bending, continuous forming, welding, heat treatment, sizing, straightening, and cutting. It has the advantages of high dimensional accuracy, uniform wall thickness, good surface quality, and high pressure resistance, but the disadvantage is that it can only produce small and medium-caliber thin-walled pipes, and it is easy to produce gray spots, unfused, and groove-like corrosion defects at the weld. The ERW steel pipe has hot-rolled coil as the raw material, and the wall thickness can be controlled within ± 0.2mm. The two ends of the steel pipe are in accordance with the American APl standard or GB / T9711.1 standard. advantage. In recent years, various natural gas pipeline network projects and gas companies have widely adopted ERW steel pipes as the main steel pipes of urban pipeline networks. ERW stands for resistance welding. Resistance welding has the characteristics of high production efficiency, low cost, material saving, and easy automation. Therefore, it is widely used in various industrial sectors such as aviation, aerospace, energy, electronics, automotive, and light industry. It is an important welding process. One. At present, it is widely used in urban gas and crude oil product transportation.

SSAW Steel Pipe

SSAW Steel Pipe

SSAW Steel Pipe: It is a spiral submerged arc welded pipe. It has a forming angle (adjustable) with the centerline of the forming pipe when the pipe is rolled. It is welded while forming. The weld seam is a spiral. The advantage is that it can produce more than the same specification. This type of steel pipe with a large diameter can be used in a wide range of raw materials. The weld can avoid the main stress. The stress is better. The disadvantage is that the geometry is poor. The length of the weld is longer than that of a straight seam pipe. For welding defects such as slag and welding deviation, the welding stress is in the state of tensile stress. General design specifications for long-distance oil and gas pipelines stipulate that spiral submerged arcs can only be used in Class 3 and 4 areas.

LSAW Steel Pipe: LSAW Steel Pipe is produced by using a single medium-thick plate as the raw material. The steel plate is pressed (rolled) in a mold or a forming machine, and the diameter is expanded by double-sided submerged arc welding. 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, strong resistance to low temperature and corrosion. When constructing high-strength, high-toughness, high-quality long-distance oil and gas pipelines, most of the steel pipes required are large-caliber thick-walled straight seam submerged arcs. According to API standards, in large oil and gas pipelines, straight seam submerged arc is the only designated applicable pipe type when passing through Class 1 and Class 2 areas such as the alpine zone, the sea floor, and dense urban areas.

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