Abstract: The edge milling process is widely used for manufacture of SSAW pipes. However,in case that proper control is not ensured,defects like welding misalignment or non-through-welding may be caused. The causes for common defects as occurring in edge-milling operation,and the influence thereby on pipe quality are analyzed,taking the structure of the edge milling machine and its working principle into account. Accordingly,preventative actions against the said defects are proposed.