Research on the nondestructive examination of narrow gap MAG welding of API 5L X65M thermomechanical treated steel

Abstract The thermomechanical treated steel API 5L X65, is the candidate material for the execution of underground and submarine pipelines having a diameter of 42″(1066.8 mm) and a wall thickness of 31.75 mm which are intended for oil and gas transport. The welding was realized by MAG welding in spray arc for the root layer and in pulsed current for filling the joint. The selected welding filler metal were ER 70S-G wire for the root welding and the E70S-6 wire for the fill layers. The pursued objective in the present paper aims at the non-destructive evaluation of the quality of welded joints using methods of visual, magnetic particle and radiographic examinations. The information resulting from the investigation of defects such as porosity, lack of fusing and incomplete penetration at the root pass showed that the welding joints made using the technological parameters established as optimal through experiments are in compliance with the quality requirements imposed by the code API 1104 – 2013.