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 pipea 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.
(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.