LSAW Steel Pipe Definition

Straight seam submerged arc welded steel pipe is also known as LSAW steel pipe (Longitudinally Submerged Arc Welding, abbreviated as LSAW). pipes made with an expanded diameter and submerged arc welding.

The finished product specifications for LSAW steel pipe is very diverse, and the weld exhibits good toughness, plasticity, uniformity, and compactness. It also benefits from large pipe diameters, thick pipe walls, high-pressure resistance, low-temperature resistance, and robust corrosion resistance. The majority of the steel pipes needed for the construction of high-strength, high-quality long-distance oil and gas pipelines are large-diameter, thick-walled straight seam submerged arc welded pipes. According to API standards, LSAW steel pipe is the only designated applicable pipe type when large oil and gas pipelines are passing through Class 1 and Class 2 areas like alpine regions, seabeds, and densely populated urban areas.

Different molding methods, it can be divided into:

UOE steel pipe: After being pre-bent at the edge, a single steel plate is then subjected to additional processes such as mechanical cold expansion, internal welding, external welding, and U and O forming.

JCOE steel pipe, or pre-welding, forming, cold expansion after welding, and other "J-C-O-E" procedures.

HME steel pipe: it is created using the "C-C-O" mandrel rolling method, and after welding, it is cold expanded.

Submerged arc welding, which also includes electroslag surfacing welding and submerged arc surfacing welding, is a type of welding in which the arc burns beneath the flux layer when welding LSAW steel pipe. It is the primary welding technique used in the creation of significant steel structures like pressure vessels, pipe sections, box beams, and columns due to its inherent advantages of stable welding quality, high welding productivity, no arc, and little smoke. The application field for submerged arc welding has not been impacted at all, despite the rapid development of numerous new effective and high-quality welding techniques. Submerged arc welding accounts for about 10% of the weight of deposited metal when compared to other fusion welding techniques, and this percentage hasn't changed much over time.

The key component after choosing the welding wire (which typically depends on the type of steel to be welded) is the supporting flux, which has a direct impact on the mechanical characteristics of the weld metal (particularly plasticity and low-temperature toughness), crack resistance, and the frequency of welding defects. Depending on the type of welding joint, the type of flux used, and the welding specification parameters, the weight ratio of welding wire to flux is welding wire: flux = 1.1 to 1.6. The amount of sintering flux is more cost-effective than smelting flux, being about 20% less.