LSAW Steel Pipe Low Temperature Corrosion Resistance

LSAW steel pipe is a professional expression term for straight seam submerged arc welded steel pipe. LSAW steel pipe is a single plate as raw material, the steel plate in the mold or molding machine in the pressure (volume) into a tube, the use of double-sided submerged arc welding and expansion from the production. Its finished product range is wide, the toughness, plasticity, uniformity and compactness of the weld are better, and it has the advantages of large diameter, thick wall, high pressure resistance and low corrosion resistance. In the construction of high-strength, high-quality long-distance oil and gas pipelines, the required steel pipe is mostly large diameter thick-walled submerged arc welded pipe. According to the API standard, in the large oil and gas transmission pipeline, when through the alpine zone, the seabed, the urban population density area 1 class, 2 type area, straight seam submerged arc welded pipe is the only designated tube type.

According to the different molding methods can be divided into: UOE steel pipe: single sheet in the edge of the pre-bending, the U molding, O molding, welding, external welding, mechanical cold expansion and other processes. JCOE steel pipe: that is, according to "J-C-O-E" pre-welding, forming, welding after cold expansion and other processes, HME steel pipe: by the mandrel rolling method according to "C-C-O" molding, welding after cold expansion and other processes.

Submerged arc welding (including buried arc surfacing and electroslag welding, etc.) is a kind of arc in the flux layer under the welding method of welding. Its inherent welding quality is stable, welding productivity is high, no arc and dust and so few advantages, making it a pressure vessel, pipe section manufacturing, box beam and other important steel structure in the production of the main welding method. Although there have been many kinds of efficient, high-quality new welding methods, but the application of submerged arc welding is still not affected. From a variety of welding methods of the proportion of the proportion of deposited metal weight, submerged arc welding about 10%, and for many years has been little change.

When the welding wire is determined (usually depending on the welded steel), the matching flux becomes a key material, which directly affects the mechanical properties of the weld metal (especially plasticity and low temperature toughness), crack resistance, weld defect rate And welding productivity. Wire and flux with the weight ratio of welding wire: flux = 1.1 ~ 1.6, depending on the type of welding joints, the type of flux used, welding specifications may be. Compared with the flux, the amount of sintered flux is more economical, about 20% less.

LSAW steel pipe main features:

1) The steel pipe has a longitudinal weld, inside and outside the weld are used a submerged arc welding into.

2) Through the whole mechanical expansion of the pipe, the steel pipe internal stress is small and uniform distribution, which can effectively prevent stress corrosion cracking, high dimensional accuracy, easy on-site welding construction.

3) the use of pre-welding precision welding process, the welding process is stable, high quality weld.

4) weld easy to achieve the production process of non-destructive testing and use of the field of non-destructive testing review.

5) product specifications range, can produce small diameter, large wall thickness can also produce large diameter, thick wall of the steel pipe.