On Metal Status Monitoring Issues of Continuous Operation Pipelines

The paper shows the relevance of the mechanical properties control of the metal of pipes and welded joints when estimating the safety of pipelines based on the results of periodic inspections. Old pipelines remain in operation in the system, but the issues of aging and degradation of the metal of the pipe and there welded joints remain without proper attention. By aging of a metal, the authors mean a gradual transition to a more stable energy state. How quickly change occurs depends on many factors. Thus, the very mode of operation of the main oil and gas pipelines contributes to the aging of the pipe metal. In addition to strain aging, there are other mechanisms for changing the mechanical properties of pipelines, for example, stress corrosion. Currently, half of all destruction on main gas pipelines occurs due to stress corrosion, the article shows the mechanism of stress corrosion. The paper contains an analysis of the aging and degradation mechanisms of pipe metal. Moreover, not only directions of development of metal control methods are shown but also have taken close look into aging and degradation during the long-term operation of pipelines.