Fracture toughness indicators of OD 1 422 mm X80 welded steel pipe

In this paper, the fracture toughness indicators of X80 welded steel pipe (OD 1 422 mm) were studied to meet the technical requirements of fracture control on Eastern China-Russia Gas Pipeline of high pressure, large diameter and high steel grade. The failure assessment diagram (FAD) technology was used to prevent the crack initiation of welded pipe. Based on the fracture mechanics analysis, the minimum average value of Charpy impact energy on welding seam and heat affected zone of X80 welded steel pipe is 80 J. In order to meet the crack arrest requirements, the correction coefficient 1.46 was introduced by means of Battelle hyperbolic method. It is determined that the minimum average value of Charpy impact energy for base metal of welded steel pipe is 245 J. The impact toughness of the trial-produced X80 welded steel pipe (OD 1 422 mm) was tested and statistically analyzed. And it is indicated that its toughness is overall higher and it can satisfy the fracture toughness indicators of Eastern China-Russia Gas Pipeline.