Analysis on Defects of Longitudinal Submerged Arc Welded Pipe Used for Oils & Gas Pipeline

When the longitudinal submerged arc welded pipe welding was completed, obvious continuous white belts were found by X-ray inspection. It was found that the chemical compositions, mechanical properties and welding process all met with the requirements of technical specification, but obvious incomplete fusion defect was found when metallographic examination. The results show that when four wires were welded, the second wire welding arc broke, the wire feed wheel stopped to feed wire, and finally resulted in the incomplete fusion defect. The defect processing method was repairing welding.