What is a LSAW Pipe?
Longitudinal Submerged Arc-Welding Pipe, LSAW， is taking the steel plate as raw material, mold it by the molding machine, then do double-sided submerged arc welding. Through this process the LSAW steel pipe will get excellent ductility, weld toughness, uniformity, plasticity and great sealing.
Diameters range and performances of LSAW pipe
Pipe O.D: Ф406.4～Ф1422.4mm（16-56in）
Pipe Length: Max.12.2m(40ft)
Wall Thickness: When the steel grade is X70, the wall thickness ranges from 6.4 to 26.4mm(0.252–1.04in);
When the steel grade is lower, the wall thickness will be increased accordingly
Product Standard: ISO3183-3; API Spec 5L, GB9711
Capacity: The annual output is 0.2million tons
The purpose of cold expansion for lsaw steel pipe:
After cold expansion for lsaw steel pipe, steel tube and pipe end diameter will increase by about one percent difference in diameter of the diameter, roundness, and the pipe ends are greatly improved, also have greatly improved the straightness of the steel pipe, steel pipe length of about 0.5% reduction in wall thickness decreases by about 0.8%.
Fully develop LSAW process should consider these changes, to determine the pipe plate width, length and thickness, and the pipe diameter in front of the enlarged diameter, in order to avoid the enlarged diameter steel pipe geometry reach the final requirements caused by substandard.
The purpose of cold expansion for lsaw steel pipe has the followings:
(1) Improve pipe end geometric dimensional accuracy of LSAW steel pipe, so that the diameter of the steel tube and pipe end, roundness, and the diameter of the pipe ends Poor meet the standard requirements, facilitate field welding construction.
(2) Reduce inhomogeneous deformation of LSAW steel pipe forming and welding process and decrease the residual stress of forming and welding of tube, and improve its distribution, improve the overall mechanical properties of the steel pipe.
(3) Inspect the steel pipe overall performance comprehensively and effectively.
(4) Improve the straight degree of lsaw steel pipe, especially for the smaller diameter LSAW pipe straight is more obvious.
Advantages of LSAW steel pipe
In the long-distance pipeline construction, pipe-line account for a large proportion, generally 35% to 40% of line pipe accounts for investment projects total investment.
How to choose a reasonable price, excellent performance pipe is particularly important to a reasonable choice of pipe to save construction investment, easy construction and safe operation of the pipeline system has a very important influence. Gas Pipelines straight seam steel high-frequency electric resistance welded steel pipe, spiral submerged arc welded pipe, LSAW steel pipe.
Limited frequency straight seam electric resistance welded steel pipe diameter range is generally limited to domestic steel Φ406.4 mm or less, the largest in Japan has reached a diameter Φ508mm. For large diameter pipe in the form of a spiral SAW, LSAW two kinds. Spiral welded steel pipe because the pipe forming process and characteristics of many shortcomings, the proportion is gradually declining in the long-distance pipeline.
In other countries, especially in many European countries, it has banned the use of spiral submerged arc welded pipe used as the main line pipe. The advantage of its unique LSAW are widely used in long-distance oil and gas pipelines, and its advantages are as follows:
(1) without the unwind process, the base material indentation, scratch less.
(2) the wrong side, slotted, and other easy-to-diameter perimeter control, excellent welding quality.
(3) the elimination of flaring basically does not exist residual stress after stress.
(4) because it is a straight line weld, the weld is short, little risk of defects.
(5) after expanding, pipe geometry accuracy is improved greatly facilitate the on-site welding.
(6) for a straight seam, less impact on the quality of anti-corrosion coating materials.
