The role of cold expansion of lsaw steel pipe
(1) Improve the geometrical dimensional accuracy of the pipe body and pipe end of the lsaw steel pipe, so that the diameter and roundness of the pipe body and the pipe end and the diameter difference between the two ends of the steel pipe meet the standard requirements, which is convenient for on-site welding construction.
(2) Reducing the uneven deformation of the forming and welding process of lsaw steel pipe, reducing the residual stress of the pipe body caused by molding and welding, improving the distribution and improving the overall mechanical properties of the steel pipe.
(3) Conduct a comprehensive and effective inspection of the overall performance of the steel pipe.
(4) The cold expansion diameter also has the effect of improving the straightness of lsaw steel pipe, especially the straightening effect on the smaller diameter straight seam submerged arc welded pipe.
After the cold expansion of the lsaw steel pipe, the diameter of the pipe body and the pipe end will increase by about one percent. The diameter, the roundness and the diameter difference between the two ends of the steel pipe are greatly improved, and the straightness of the steel pipe is also greatly improved. The length is reduced by about 0.5%, and the wall thickness is reduced by about 0.8%. In the development of the lsaw steel pipe process, these changes should be fully considered to determine the width, length and thickness of the pipe sheet and the outer diameter of the steel pipe before the diameter expansion, so as to avoid the geometrical dimension of the steel pipe after the expansion is not up to the final requirements.