CVN-KJC correlation model for API X65 gas pipeline

Reliable determination of fracture toughness of different materials is critically important. However, standard fracture toughness testing methods are difficult and costly. In order to simplify the determination of fracture toughness, several correlations between fracture toughness and Charpy impact energy (CVN) have been proposed by different researchers. In the present work, a new linear model was developed for estimation of fracture toughness (KJC), based on CVN, and yield strength data, in base, seam weld, and girth weld metals of an API X65 gas pipeline. The predicted values of KJC from the suggested relation, with maximum and mean error values of 6.7% and 4.4%, respectively, was found to be in good agreement with the valid fracture toughness test results obtained from compact tension specimens following ASTM E1820 standard.