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Steel Pipe Classification and Process

Date:2019-06-10    keywords:seamless steel pipe, LSAW, ERW
China's steel pipe industry has a long history of nearly sixty years, but this can only be said to be the history of seamless steel pipes. Straight seam steel pipes are still a new thing compared to seamless steel pipes, it exists only a short ten years. But in this short span of ten years, the straight seam steel pipe encountered China's rapid development, which undoubtedly became the golden age of straight seam steel pipe development in China. In the past ten years, China's straight seam steel pipe industry continued to develop, innovate and surpass. At present, it has reached the world advanced level in terms of output, quality, type, technical level and production equipment.

The following is a brief introduction to this straight seam steel pipe that plays a pivotal role in China's development.

As the name implies, a straight seam steel pipe is a steel pipe whose weld is parallel to the longitudinal direction of the steel pipe. According to different production processes, straight seam steel pipes can be divided into high-frequency straight seam steel pipes (abbreviation: ERW) and submerged arc welded straight seam steel pipes (abbreviation: LSAW).

The full name of ERW (Electric Resistance Welding) steel pipe is “high-frequency electric resistance welded steel pipe. It is to roll the hot-rolled steel coil and then roll it into a round pipe along the length of the strip with a winch, and then use the high frequency at the joint of the round pipe. The current is liquefied and fused by the edge of the round tube, and the welding process is rolled. The welding process of the high-frequency resistance welded steel pipe is different from that of the ordinary welded pipe. The weld is formed by melting the base material of the steel strip body, and the mechanical strength is better than that of the general welded pipe. .

LSAW (longitudinally submerged Arc Welding) is called double-sided submerged arc straight seam welded pipe. It is made of medium or thick plate or open flat coil. The steel plate is pressed into a round pipe by a molding machine, and then the inner and outer sides of the round pipe are welded. The welding wire is welded by a submerged arc welding process. 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 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.

At present, China's straight seam steel pipe market has broad application prospects, mainly in the following six areas: one is the application of oil and natural gas to straight seam steel pipe; the other is the application of urban gas to straight seam steel pipe; the third is urban construction, water conservancy, electric power and other projects. The application of straight seam steel pipe; the fourth is the application of oil casing to straight seam steel pipe; the fifth is the application of heating boiler and household appliances to straight seam steel pipe; the sixth is the application of straight seam steel pipe for stations and terminal buildings.

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