Evaluation of the Residual Service Life of Main Pipelines with Regard for the Action of Media and Degradation of Materials

We proposed new procedures for the evaluation of the residual service life of main pipelines with surface cracks under the action of a long-term constant gas pressure in gas pipelines, a variable pressure in oil pipelines, hydrogenation, and soil corrosion. The degradation of the materials is taken into account. Since the time dependence of the degree of degradation is insignificant, it is analytically described by linear dependences. The energy approach is used to determine the residual service life of the pipes. The corresponding computational models (differential equations with initial and final conditions) are developed. For specific pipe materials (Kh52, Kh60, and Kh70 steels), the residual service life is computed under long-term static and variable loads, in the presence of hydrogenation and soil corrosion with regard for the degradation of the materials for 30 yr.