LSAW pipe meaning

　　Longitudinally Submerged Arc Welding pipe(abbreviated as LSAW pipe). The Longitudinally Submerged Arc Welding (LSAW) is produced by using a single plate as a raw material, pressing (rolling) the steel plate into a pipe blank in a mold or a molding machine, and adopting double-sided submerged arc welding and expanding the diameter. The finished product has a wide range of specifications, and the weld has good toughness, plasticity, uniformity and compactness, and has the advantages of large pipe diameter, thick pipe wall, 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 required steel pipes are large-diameter thick-walled straight seam submerged arc welded pipes. According to the API standard, in large oil and gas pipelines, the straight seam submerged arc welded pipe is the only designated pipe type when passing through Class I and Class 2 areas such as high-altitude zones, seabeds, and urban densely populated areas. According to different molding methods, it can be divided into:

　　UOE welded pipe: after the pre-bending of the single steel plate, U-forming, O-forming, internal welding, external welding, mechanical cold expansion and other processes;

　　JCOE welded pipe: it is according to the process of "J-C-O-E" pre-welding, forming, cold-expanding after welding;

　　HME welded pipe: It is formed by the "C-C-O" by the mandrel rolling method, and the process of cold expansion after welding.

　　The main technical parameters of LSAW (straight seam submerged arc welded pipe) are as follows:

　　Wall thickness: 6.4-23.8mm (0.252-0.94in) in X80 steel grade and 6.4-26.4mm (0.252-1.04in) in X70 steel grade. The wall thickness can be increased to varying degrees as the material is lowered.

　　Product standard: ISO3183-3, API Spec 5L, GB9711, etc.

　　Straight seam submerged arc welded steel pipe diameter up to Φ406.4-Φ1422.4mm

　　The steel pipe can be up to 12.2m long and the wall thickness is 6.4-26.4mm at the ×70 steel grade.

　　Main features of LSAW pipe:

　　1) The steel pipe has a longitudinal weld, and the inner and outer welds are welded by a submerged arc welding.

　　2) After the overall mechanical expansion treatment, the internal stress of the steel pipe is small and evenly distributed, which can effectively prevent stress corrosion cracking, high dimensional accuracy, and is convenient for on-site welding construction.

　　3) Using the process of pre-weld after-welding, the welding process is stable and the weld quality is high.

　　4) Welds are easy to achieve non-destructive testing during production and non-destructive testing in the field during use.

　　5) The product specification range is large, which can produce small diameter, large wall thickness and can also produce large diameter and large wall thickness steel pipe.