Influence of Laminations on the Edge of Steel Plates on Quality of Double-side Submerged-arc Welding Steel Pipes

Laminations of over-standard or within-standard defects on the edge of steel plates would affect the welding quality and its inspection in the manufacturing process of double-side submerged-arc welding steel pipes, and result in quality issues. Through the integrated analysis of ultrasonic testing (UT), radiographic testing (RT) and metallographic examinating results, the quality issues caused by the laminations in the center and subsurface positions were analyzed respectively. In order to improve the quality of oil and gas pipelines, effective and targeted precautions were proposed from the aspects of the reduction of permissible values of laminations on the edge of steel plates and the adjustment of welding procedures.