LSAW standards for Longitudinal Submerged Arc Welding, one welding type, by one straight welding seam or two straight welding seams. Sizes from 325mm to 1420mm usually by one straight welding seam while two straight welding seams may be taken for outer diameters 914.4mm in accordance the relative standard for the pipe and the wall thickness.

The advantage of LSAW steel pipe is the thickness could be from 8mm to 120mm with diameters from 325mm to 1820mm with high steel grade. They are widely used in heavy steel structure fluid transportation pipe line etc.