Straight seam steel pipes can be divided into resistance welded straight seam steel pipes and submerged arc welded straight seam steel pipes in terms of welding process, among which resistance welded straight seam steel pipes are divided into high frequency welded straight seam steel pipes, intermediate frequency welded straight seam steel pipes, low frequency welded straight seam steel pipes, The submerged arc welded straight seam steel pipe is also called double-sided submerged arc straight seam steel pipe or LSAW straight seam steel pipe. Among them, LSAW is (the abbreviation of Longitudinally Submerged Arc Welding is LSAW). Electric resistance welded straight seam steel pipe is also called ERW straight seam steel pipe. ERW is (Electric Resistance Welding, abbreviated as ERW for short). The following are the production methods of each welding process:
High frequency welded straight seam steel pipe is also called ERW straight seam steel pipe
ERW is a general term for electric resistance welded steel pipes, and ERW is the initial letter of the corresponding English words. Electric resistance welded steel pipes are divided into AC welded steel pipes and DC welded steel pipes.
AC welding is divided into low frequency welding, intermediate frequency welding, super intermediate frequency welding and high frequency welding according to the frequency. High-frequency welding is mainly used for the production of thin-walled steel pipes or ordinary wall-thick steel pipes, and high-frequency welding is divided into contact welding and induction welding. DC welding is generally used for small diameter steel pipes.
Therefore, in general, the high-frequency welded pipe is included in the ERW welded pipe, which is a kind of ERW welded pipe produced by the high-frequency welding process. ERW straight seam welded pipe is a steel pipe with advanced product performance and relatively economical in the field of oil and gas storage and transportation.
Submerged arc welding straight seam steel pipe is also called double-sided submerged arc welding straight seam steel pipe or LSAW straight seam steel pipe. LSAW steel pipe is produced with a single medium-thick plate as raw material, which is pressed (rolled) into a tube blank in a mold or forming machine, and produced by double-sided submerged arc welding and diameter expansion. It has a wide range of finished product specifications, good toughness, plasticity, uniformity and compactness of the weld seam, and has the advantages of large pipe diameter, thick pipe wall, high pressure resistance, low temperature resistance and strong corrosion resistance.
When building high-strength, high-quality long-distance oil and gas pipelines, most of the required steel pipes are large-diameter thick-walled longitudinal submerged arc welded pipes. According to API standards, in large oil and gas pipelines, when passing through Class 1 and Class 2 areas such as alpine regions, seabeds, densely populated urban areas, etc., LSAW pipes are the designated applicable pipe types.