LSAW steel pipe (Longitudinally Submerged Arc Welding is abbreviated as LSAW) is a professional expression term for straight seam submerged arc welded steel pipe. LSAW steel pipe is produced by using a single medium-thick plate as a raw material, pressing (rolling) the steel plate into a tube blank in a mold or forming machine, and using double-sided submerged arc welding and expanding the 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 corrosion resistance. When constructing high-strength, 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.
According to different molding methods, it can be divided into:
UOE steel pipe: After pre-bending the edge of a single steel plate, it undergoes U forming, O forming, internal welding, external welding, mechanical cold expansion and other processes.
JCOE steel pipe: It is pre-welded, shaped, cold-expanded after welding according to "J-C-O-E".
HME steel pipe: formed by the mandrel rolling method according to "C-C-O", cold-expanded after welding and other processes.
The main technical parameters of LSAW (Longitudinal Submerged Arc Welded Pipe) are as follows:
Wall thickness: up to 6.4-23.8mm (0.252-0.94in) in X80 steel grade; up to 6.4-26.4mm (0.252-1.04in) in X70 steel grade. When the material is reduced, the wall thickness can be increased to varying degrees.
Product standards: ISO3183-3, API Spec 5L, GB9711, etc.
The diameter of the straight seam submerged arc welded steel pipe can reach Φ406.4-Φ1422.4mm.
The maximum length of the steel pipe is 12.2m, and the wall thickness is 6.4-26.4mm at the level of X70 steel.
Main features of LSAW steel pipe:
1) The steel pipe has a longitudinal weld, and the inner and outer welds are welded by a submerged arc weld.
2) After the overall mechanical expansion process, the internal stress of the steel pipe is small and evenly distributed, which can effectively prevent stress corrosion cracking, high dimensional accuracy, and easy on-site welding construction.
3) The process of precision welding after pre-welding is adopted, the welding process is stable, and the quality of the welding seam is high.
4) Welding seam is easy to realize non-destructive flaw detection during production and re-examination of non-destructive flaw detection in the field during use.
5) The range of product specifications is large, which can produce both small diameter and large wall thickness steel pipes with large diameter and large wall thickness.
